Clin Auton Res (2009) 19:275–316 DOI 10.1007/s10286-009-0030-5

ABSTRACTS

Wednesday, November 11, 2009 Oral Presentations Postural tachycardia syndrome versus inappropriate sinus tachycardia: role of autonomic modulation S.Y. Paranjape, B.K. Black, E.M. Garland, I. Biaggioni, D. Robertson, S.R. Raj Vanderbilt University, Nashville, TN, USA Background: Both postural tachycardia syndrome [POTS; heart rate (HR) increase [30 bpm lying to standing] and inappropriate sinus tachycardia (IST; mean daytime HR [ 100 bpm or 24 h HR [ 90 bpm) display sinus tachycardia. It is unclear if these are distinct disorders or have similar autonomic qualities. One hypothesis is that IST is a disorder of abnormal intrinsic sinus node automaticity, while POTS is a disorder of autonomic modulation. We prospectively tested the hypothesis that intrinsic heart rate (IHR; after pharmacological autonomic blockade) would be increased in IST, but normal in POTS. Methods: Patients with POTS [32F 1M, 30 ± 1 (mean ± SEM) years], or IST (5F, 39 ± 6 years), and control subjects (CON; 11F, 29 ± 3 years) underwent blockade with propranolol 0.2 mg/kg IV followed by atropine 0.04 mg/kg IV while supine. HR was assessed after propranolol and after atropine. Sympathetic contribution to HR (SYM; resting HR minus post-propranolol HR) and parasympathetic contribution to HR [PSYM; IHR (post atropine) minus the post-propranolol HR] were calculated. Results: Resting HR was higher in IST (111 ± 9 bpm) than in POTS (73 ± 2 bpm; P \ 0.001) and CON (64 ± 2 bpm; P \ 0.001), but not significantly higher in POTS than CON (P = 0.059). Following propranolol, HR in POTS (62 ± 2 bpm) was not different from CON (56 ± 2 bpm; P = 0.139) and both were lower than IST (79 ± 3 bpm; P \ 0.001 for each). IHR was not different among the three groups (IST: 113 ± 5 bpm; POTS: 107 ± 2; CON: 107 ± 4; P = 0.546). SYM was higher in IST (32 ± 7 bpm) than either POTS (12 ± 1 bpm; P \ 0.001) or CON (8 ± 1 bpm; P \ 0.001), with no difference between POTS and CON (P = 0.390). PSYM was highest for CON (51 ± 4), nonsignificantly lower for POTS (45 ± 2 bpm; P = 0.255) and significantly lower for IST (33 ± 5 bpm; P = 0.016). Conclusions: IHR was not different among patients with IST, POTS and control subjects suggesting no differences in sinus node

automaticity in these disorders. At rest, patients with IST have more sympathetic tone and less parasympathetic tone than either POTS or controls.

Evaluation of a novel non model driven assessment of cardiac autonomic activity: response of patients with postural tachycardia syndrome (POTS) R. Schondorf1, J. Benoit1, M.J. Lafitte2 1 Department of Neurology, Jewish General Hospital, McGill University, Montreal, QC, Canada; 2 DyAnsys, Geneva, Switzerland We have previously described the kinematics of the steady state response to combined HUT and graded heat stress in 13 subjects using a novel time domain method that decomposes beat to beat changes in R–R intervals (RRI) into components that reflect parasympathetic and sympathetic cardiac autonomic activity. As orthostatic stress increased (HUT and heat stress) cardiac sympathetic velocity increased incrementally and predictably. In contrast, changes in cardiac parasympathetic velocity were minimal. To determine whether the responses seen during high orthostatic stress are also evident in orthostatically intolerant individuals, we studied 19 patients with POTS at rest and during 80
head-up tilt (HUT) alone and following superimposed MAST pants inflation, a maneuver that attenuates orthostatic stress. In these patients, HUT decreased RRI from an average of 751–481 ms while MAST pants inflation increased RRI to 598 ms. During HUT alone, sympathetic velocity increased from 7.6 to 22.7 AU/s while MAST pants inflation reduced sympathetic velocity to 15.1 AU/s. These changes in sympathetic velocity were directionally consistent in all 19 patients. In contrast, the changes in parasympathetic velocity during HUT (1.9–2.3 AU/s) or MAST pants inflation (2.3–2.5 AU/s) were minimal and were not directionally consistent (6 patients decreased velocity and 13 increased in each case). The magnitudes of the changes in RRI and sympathetic velocity in patients with POTS were nearly identical to those of normal subjects during combined HUT and heat stress (RRI 748–489 ms; sympathetic velocity 8.6– 26.8). These data provide further confirmation of our method’s ability to describe the physiological underpinnings of the cardiac autonomic response to varying levels of orthostatic stress both in normal subjects and in patients with significant orthostatic intolerance.

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Postural orthostatic tachycardia syndrome with reduced sympathetic neural outflow A. Diedrich1, K. Sato1, L. Diedrich2, A. Gamboa1, S.R. Raj1, I. Biaggioni1, D. Robertson1 1 Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, TN, USA; 2 Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, USA Central hyperadrenergic innervations, norepinephrine (NE) transporter deficiency, partial dysautonomia, or abnormal blood volume has been discussed as possible underlying mechanism in postural orthostatic tachycardia syndrome (POTS). The findings about sympathetic neural outflow in POTS are rare and inconsistent. We studied 14 patients with POTS (14 females, age 30.6 ± 6.9, BMI 22.9 ± 3.6) and 11 healthy volunteers without any history of orthostatic intolerance (10 females, age 31.3 ± 9.5, BMI 23.3 ± 4.1). MSNA was recorded from the left peroneal nerve. Satisfactory recordings were defined by heart pulse synchronicity; typical response to Valsalva; and no change during tactile or auditory stimulation. Physiological parameters were recorded during a graded tilt (15
steps, 5 min till 75
). Blood samples were taken supine, at 60
or final period. Studies were performed under standard diet and conditions at the Vanderbilt Clinical Research Center. Mean tilt time was not different (23.5 ± 3.5 vs. 28.8 ± 11.3 min, POTS vs. healthy). Orthostatic symptoms but not hypotension was the major reason for abort tilt in POTS. Patients showed higher supine heart rate (75 ± 2 vs. 65 ± 3 bpm, n = 14/11) but normal blood pressure (BP). Heart rate and its response during all tilt periods were higher in POTS (108 ± 4 vs. 86 ± 4 bpm, n = 7/8, at 45
) while BP was maintained. POTS showed lower MSNA activity in supine (10.0 ± 1.8 vs. 20.3 ± 2.3 bursts/min, n = 14/11) and during all tilt periods (26.56 ± 4.068 44.9 ± 2.3 bursts/min, n = 7/8, at 45
). The response expressed as changes in normalized burst area was diminished in POTS. Catecholamine levels were not significantly different (supine: 204.9 ± 31.53 vs. 151.3 ± 15.79; upright: 574.2 ± 81.68 vs. 499.2 ± 56.96 pg/ml). In conclusion, there exists a subgroup of POTS which have reduced sympathetic neural outflow. NE transporter deficiency or partial dysautonomia could be a possible reason for this different result.

The autonomic nervous system and nitric oxide in postural tachycardia syndrome A. Gamboa, L.E. Okamoto, A. Diedrich, G. Farley, S. Paranjape, B. Black, I. Biaggioni Department of Medicine, Vanderbilt University, Nashville, TN, USA Postural tachycardia syndrome (POTS) is a hyperadrenergic disorder characterized by an excessive increase in heart rate upon standing (more that 30 bpm) and extreme orthostatic and exercise intolerance. We tested the hypothesis that an excessive sympathetic drive and an impaired nitric oxide (NO) function are implicated in this condition. We gauged the tonic effect sympathetic activity has in these patients by the decrease in blood pressure induced by the ganglionic blocker trimethaphan. NO function was assessed by the increase in blood pressure induced by nitric oxide synthase inhibition with L-NMMA. The later was performed during autonomic withdrawal to eliminate effects of NO mediated through interactions with the sympathetic nervous system. Using this approach, we studied 9 POTS patients and

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Clin Auton Res (2009) 19:275–316 14 gender and age matched healthy controls. As expected at baseline there was no difference in systolic blood pressure between groups (SBP, 102 ± 3 and 95 ± 4 mmHg for controls and POTS respectively). Autonomic blockade with trimethaphan produced a greater decrease in SBP in the POTS group (-10 ± 3 vs. 3 ± 2 mmHg in controls). SBP was then restored with titrated doses of phenylephrine to achieve similar baseline values (97 ± 3 and 101 ± 3 mmHg in POTS and controls). On the other hand, we found no difference in the pressor response to L-NMMA between groups, The increase in SBP at any given amount of L-NMMA was similar in both groups (5.2 ± 0.7 vs. 5.5 ± 0.9 mmHg/mg L-NMMA for controls and POTS patients respectively, P = 0.826). These results provide further evidence of an overactive sympathetic nervous system in POTS but do not provide evidence for impaired NO function in POTS. We cannot rule out a defect in NO/sympathetic interactions, which were removed by our study paradigm.

Paradox of high levels of angiotensin II and low angiotensin converting enzyme 2 activity in postural tachycardia syndrome S.R. Raj, E. Garland, I. Biaggioni, B.K. Black, H. Mustafa, D. Robertson Vanderbilt University, Nashville, TN, USA Background: We have previously shown that patients with postural tachycardia syndrome (POTS; heart rate increase [30 bpm on standing) are hypovolemic and do not have adequate compensatory stimulation of renin activity or aldosterone. Given the apparent disconnect, we sought to better delineate the response of the reninangiotensin-aldosterone system (RAS) in POTS. Methods: Patients with POTS (n = 25; 23 female, 33 ± 2 years) and healthy control subjects (n = 8; all female, 28 ± 2 years; P = NS for age) underwent a blood volume assessment using a 131I-Albumin test. RAS hormones were measured, including plasma renin activity, aldosterone and angiotensin (ANG) species (ANG I, ANG II, ANG 1– 7). Crude measures of angiotensin converting enzyme (ACE; ANG II/ ANG I) and ACE2 (ANG 1–7/ANG II) activity were calculated. Group comparisons were made using Student’s t test. Data are presented as mean ± SEM. Results: Total blood volume deficits were greater in POTS (P; -9.9 ± 1.7%) than controls (C; -2.6 ± 3.6; P = 0.048). Despite the blood volume deficit in POTS, neither standing plasma renin activity (P: 8.1 ± 2.0 ng/(nl h) vs. C: 7.5 ± 1.0 ng/(nl h); P = 0.8) nor standing aldosterone (P: 26.7 ± 4.7 ng/dl vs. C: 31.1 ± 3.4 ng/dl; P = 0.6) were increased in POTS. In POTS patients, ANG II was significantly higher (41.3 ± 3.2 pg/ml vs. C: 22.7 ± 2.7 pg/ml; P \ 0.001), ANG I was non-significantly higher (P: 77.7 ± 9.8 pg/ml vs. C: 55.5 ± 5.4 pg/ml; P = 0.2), but ANG 1–7 was not increased (P: 7.9 ± 0.4 pg/ml vs. C: 7.2 ± 0.6 pg/ml; P = 0.4). ACE activity was non-significantly higher in POTS (P: 0.70 ± 0.11 vs. C: 0.43 ± 0.05; P = 0.2) but ACE2 activity was LOWER in POTS (P: 0.22 ± 0.02 vs. C: 0.35 ± 0.05; P = 0.006). Conclusions: Patients with POTS have an unusual renin-angiotensin-aldosterone profile. Despite low blood volume, renin activity and aldosterone are elevated. In contrast, ANG II is markedly elevated. The disconnect between ANG II and ANG 1–7 and aldosterone suggest decreased ACE2 activity (limiting ANG II degradation) and problems in AT-1 receptor signaling. These data are consistent with the Stewart hypothesis that ACE2 may be reduced in POTS.

Clin Auton Res (2009) 19:275–316

Menstrual cycle effects on neurohumoral regulation of hemodynamics during 2 h of standing in the postural orthostatic tachycardia syndrome Q. Fu1,2, T.B. VanGundy1, M.M. Galbreath1,2, S. Shibata1,2, B.D. Levine1,2 1 Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; 2 The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA Background: More than one million Americans, primarily premenopausal women, suffer from the postural orthostatic tachycardia syndrome (POTS). However, the underlying pathophysiology remains unclear. We tested the hypothesis that the fluctuations of female sex hormones during the normal menstrual cycle would affect neurohumoral regulation of hemodynamics during prolonged orthostasis in patients with POTS. Methods: Ten normally menstruating female POTS patients between the ages of 15 and 42 were studied during the early follicular (EFP) and mid-luteal phase (MLP) of their menstrual cycles. All consumed a diet containing 200 mEq sodium, 100 mEq potassium, and 1,000 mg calcium three days prior to testing. Hemodynamics, including blood pressure (BP), heart rate (HR), cardiac output (CO, C2H2 rebreathing), stroke volume (SV = CO/HR), and total peripheral resistance (TPR = mean BP/CO) were measured supine and every 10 min during 2-h active standing. Blood samples for plasma renin activity (PRA), aldosterone (ALDO), and catecholamines were collected in the supine position, and after 30, 60 and 120 min of standing. Results: BP remained stable, while HR increased gradually during 2-h standing; these responses were similar between menstrual phases. Both CO and SV decreased progressively during prolonged standing and were lower in EFP than MLP (P = 0.019 and 0.003). TPR increased gradually during prolonged standing, and was higher in EFP than MLP (P = 0.029). Both PRA [9.2 ± 5.8 (SD) vs. 12.7 ± 8.6 ng/(ml h), P = 0.035] and ALDO (42.5 ± 21.7 vs. 55.1 ± 24.6 ng/dl, P = 0.019) were significantly lower in EFP than MLP after 2 h of active standing. However, plasma catecholamine responses were not different between phases. Three patients had presyncope during EFP and the average standing time was 91 ± 39 min, while only one patient developed presyncope during MLP and the standing time was 115 ± 17 min (P = 0.142). Conclusions: These results suggest that the menstrual cycle could modulate the renin-angiotensin-aldosterone axis, and affect cardiac output and peripheral vascular resistance during prolonged orthostasis in POTS patients. It appears that the fluctuations of female sex hormones during normal menstrual cycles may contribute to orthostatic intolerance in these patients. Supported by NIH K23 (HL0752 83) and GCRC grant (RR00633).

Low iron storage and anemia in postural tachycardia syndrome (POTS) in adolescents I.T. Jarjour, L.K. Jarjour Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA Objective: Low iron storage was reported in children and adolescents with neurally mediated syncope (NMS) (J Pediatr 153:40–44, 2008). While reduced red cell mass suggestive of anemia has been reported in POTS, iron indices and hemoglobin (Hb) data were not reported. We investigated whether POTS, like NMS, is also associated with low iron storage and anemia. Methods: 32 children evaluated in 2007 and 2008 for probable POTS by a standing or tilt test or both at a tertiary care Pediatric Neurology Clinic were included in a retrospective study after IRB approval. We measured serum ferritin (SF) and hemoglobin (Hb) values. We defined

277 iron deficiency as SF \ 12 l/L, low iron storage as SF B 25 l/L, anemia as low Hb values for age and sex, and POTS as C2 symptoms of orthostatic intolerance[3 months and increased HR of[30 BPM or HR of [120 BPM within 10 min of standing or 70
tilt. Results: 24 children had POTS, ages 12–18 years, 17 (71%) were females. SF values ranged from 2 to 289 lg/L (median 25) and Hb values from 11.5 to 15.9 g/L (median 12.6). Patients with POTS when compared with normal US population of pediatric subjects had a higher prevalence of low iron storage (50 vs. 14%), iron deficiency (25% of teenage girls vs. 9%, and 16% of teenage boys vs. 1%), and anemia (18% of teenage girls vs. 1.5%, and 43% of teenage boys vs. 0.1%). Conclusions: Low iron storage and mild anemia are associated with POTS suggesting that reduced red cell mass in patients with POTS may be related to iron deficiency, and that low iron storage is a potentially pathophysiologic factor in both POTS and NMS.

Thursday, November 12, 2009 Oral Presentation Magnetic resonance anatomical and perfusion imaging in multiple system atrophy P. Novak1, O. Zurkiya2,3, P. Zhao2, D. Alsop3, V. Novak2 1 Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA; 2 Department of Medicine, Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 3 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA Background: Multiple system atrophy (MSA) is a progressive neurodegenerative disorder of unknown etiology. The goal of this study was to evaluate regional brain volumes and cerebral perfusion in MSA using high resolution MRI. Study design: The MRI data were obtained in eight MSA subjects (mean age = 61) and 37 age-matched controls. High-resolution 3 Tesla MR images were acquired with 3D magnetization prepared rapid gradient echo (MP-RAGE) and perfusion images obtained with 3D continuous arterial spin-labeling (CASL). Images were segmented and co-registered using standard templates via SPM. Results and discussion: Normalized brain tissue volume was decreased in MSA compared to controls in the cerebellum and brain stem as may be expected (6.25% intracranial volume vs. 5.17%, P \ 0.0004 and 0.8 vs. 0.7%, P \ 0.04 respectively). The gyrus rectus, a structure previously linked to depression, showed a decrease in MSA (left side 0.0082 vs. control 0.015%, P \ 0.0072 and right 0.0106 vs. control 0.0157%, P \ 0.03). Unexpectedly, MSA patients showed increases in several regions including the hippocampus (left side 0.41 vs. control 0.38%, P = 0.02 and right 0.40 vs. control 0.37%, P = 0.007), the middle frontal gyrus, the lateral orbitofrontal gyrus, the postcentral gyrus, the supramarginal and angular gyri. Perfusion in frontal lobes was reduced [left side MSA 33.4 ml/(100 g min) vs. control 40.7, P \ 0.05, right side 33.5 vs. control 40.3, P \ 0.07]. Conclusions: These data further elucidate the brain regions affected by MSA and can help in understanding its clinical presentation. Interestingly, CASL imaging did not show statistically significant differences in perfusion for the cerebellum, though atrophy of this region is known to occur in MSA and volume decrease was noted with MP-RAGE imaging. As MSA is a progressive neurodegenerative disorder, the reason for volume increases in some regions is not clear and may be some form of compensatory, yet unknown, mechanism.

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278 The authors would like to acknowledge the University of Massachusetts MSA Clinical Trial NCT00750867.

Differential involvement of periaqueductal gray columns in multiple system atrophy A.M. Schmeichel1, P.A. Low1, J.E. Parisi2, E.E. Benarroch1 1 Department of Neurology, Mayo Clinic, Rochester, MN, USA, 2 Department of Anatomic Pathology, Mayo Clinic, Rochester, MN, USA The midbrain periaqueductal gray (PAG) consists of functionally different columns that provide an interface between the limbic cortex and hypothalamus rostrally and brainstem nuclei caudally. We sought to determine whether there was differential involvement of distinct PAG columns in multiple system atrophy (MSA). Brains were obtained at autopsy from 13 patients (10 M, 3 F, age 61 ± 3) with neuropathologically proven MSA, and 13 age-matched controls (8 M, 5 F, age 67 ± 4) with no history of neurologic disease. Brains were fixed in 4% paraformaldehyde and coronal 50 micron sections were obtained throughout the PAG and immunostained for tyrosine hydroxylase (TH) or nitric oxide synthase (NOS) and co-stained with thionin. Thirteen 50 lm sections were processed for a-synuclein to map the distribution of glial cytoplasmic inclusions. Stereological quantitation was performed separately in the ventrolateral, lateral, dorsolateral, and dorsomedial columns of the PAG. There was a significant loss of TH (presumably dopaminergic) neurons in the ventrolateral PAG compared to the total estimated cell numbers in controls (21,488 ± 8,324) versus MSA (11,727 ± 5,984, P \ 0.01), but preservation of NOS neurons in the dorsolateral PAG (27,484 ± 2,626 vs. 27,576 ± 1,653). GCIs were more abundant in the ventrolateral and lateral than in the dorsolateral and dorsomedial columns, particularly at caudal levels. Our findings indicate that, in MSA, PAG columns projecting to brainstem autonomic nuclei (ventrolateral and lateral) are more affected than those connected with other structures (dorsolateral and dorsomedial). This is consistent with a system degeneration of central autonomic structures in MSA.

Brain structural changes and functional outcomes in older people with altered cerebral autoregulation K. Hu1, M. Aoi1,2, P. Zhao1, L. Desrochers1, M.-T. Lo1, Y. Liu7, C.-K. Peng3, P. Novak4, M. Selim5, L.A. Lipsitz1,6, V. Novak1 1 Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2 Department of Mathematics, North Carolina State University, Raleigh, NC, USA; 3 Division of Interdisciplinary Medicine and Biotechnology and Margret and H.A. Rey Institute for Nonlinear Dynamics in Medicine, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, USA; 4 Department of Neurology, University of Massachusetts, Worcester, MA, USA; 5 Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 6 Hebrew Senior Life Center, Boston, MA, USA; 7 DynaDx Corporation, Mountain View, CA, USA Cerebral autoregulation (CA) is an important mechanism that helps to maintain stable cerebral blood flow (CBF) despite of variations in perfusion blood pressure (BP) under physiological and pathological conditions. Impaired CA leads to greater dependence of CBF on BP. To test the hypothesis whether the CA alteration affects brain

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Clin Auton Res (2009) 19:275–316 structure and functional outcomes in older adults, we studied 118 subjects (mean age = 65.40 ± 7.93 years) including 41 controls, 21 with type 2 diabetes, 16 with hypertension, and 40 with prior stroke. To assess CA, BP waveform from a finger (portapres) and cerebral blood flow velocity (BFV) in the middle cerebral arteries (transcranial Doppler) were recorded continuously during 5-min supine rest conditions. The BP-BFV phase shift obtained from a newly designed multimodal pressure-flow method was used as a CA index, i.e., small value indicates reduced CA. To measure brain structural changes, gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) volumes were obtained from MRI in a subset (106) of subjects, and normalized by total brain volume. To assess functional outcomes, gait speed (GS) was measured from 12-min hallway walk in 97 subjects and instrumental activities of daily living (IADL) based on questionnaire was obtained in 56 subjects. We found that subjects with smaller GM volume had significantly smaller CA index (P = 0.003), independent of the effects of age, sex, BMI, and mean baseline blood pressure. Subjects with larger CA index had significantly faster GS (P = 0.018), independent of the effects of age, BMI, CSF volume and sex. There was a negative relationship between the CA index and IADL score (P \ 0.0001), where higher score on the IADL is associated with more limited daily activity. These results suggested that impaired CA is linked to increased brain structure changes, and worse functional outcomes in older people.

Relationship between regional brain atrophy and inflammation in type 2 diabetes mellitus V. Novak1, P. Zhao1, K. Hu1, M. Munshi1, D. Alsop2, A. Abduljalil3, B. Manor1, L. Desrochers1, P. Novak4 1 Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 3 Department of Radiology, The Ohio State University, Columbus, OH, USA; 4 Department of Neurology, University of Massachusetts, Worcester, MA, USA Background: Type 2 DM is associated with micro- and macrovascular disease, a major risk factor for stroke and dementia. Microvascular disease manifests as white matter hyperintensities on MRI, regional atrophy and functional decline. Inflammation further affects microcirculation and contributes to arteriolosclerosis. We studied the effects of inflammation on regional brain volumes in older diabetic people. Methods: We studied 45 type 2 DM (63.3 ± 1.2-year-old, 51– 79 years) and 59 controls (66.2 ± 1.0-year-old; 50–83 years) using high resolution MRI at 3 Tesla. Anatomical images (MP-RAGE, FLAIR) were co-registered on standard template and segmented to calculate regional volumes of grey (GM) and white (WM) and cerebrospinal fluid (CSF) in the frontal, temporal, parietal and occipital regions. The association of brain volumes with plasma inflammatory markers (intracellular adhesion molecule (sICAM), vascular adhesion molecule (sVCAM), C-reactive protein (CRP), tumor necrosis factor (TNF) was analyzed using multivariate models and MANCOVA. Results: Inflammatory markers had different effects on regional brain volumes. sICAM was associated with atrophy across all regions in the DM group (P = 0.001), with the most significant effects in the frontal and parietal regions (P = 0.01). These effects were independent of age and body mass. In the control group, age had the most significant effects on CSF and GM volumes in the control group, and sICAM was associated greater GM volume in the frontal (P = 0.03) and parietal (P = 0.04). sICAM and sVCAM levels were correlated, and CRP was correlated with TNF. The sICAM levels were not different between the groups.

Clin Auton Res (2009) 19:275–316 Conclusions: Soluble adhesion molecules facilitate cell migration into damaged vascular tissue and play an important role in the immunoinflammatory reaction. Inflammatory cytokines may reflect an active vascular process that is specific for different vascular beds and brain regions. Frontal and parietal regions with high energy demands are more vulnerable to the effects of DM in the brain. Supported by: ADA 1-06-CR-25, NIH- 1R0 NS045745-04.

Association of olfactory dysfunction with autonomic failure in Parkinson disease D.S. Goldstein, L. Sewell, C. Holmes Clinical Neurocardiology Section, CNP, DIR, NINDS, NIH, Bethesda, MD, USA Background: Olfactory dysfunction and symptoms and signs of autonomic failure are prominent non-motor manifestations of Parkinson disease (PD). In this study, we assessed whether olfactory dysfunction is related to baroreflex failure or to sympathetic noradrenergic failure in PD. Methods: University of Pennsylvania Smell Identification Test (UPSIT) scores were expressed as a function of orthostatic blood pressure changes, indices of baroreflex-cardiovagal and baroreflex-sympathoneural function, and 6-[18F]fluorodopamine-derived radioactivity in the cardiac interventricular septum and free wall and renal cortex in 25 PD patients. Results: UPSIT scores were lower in PD with than in PD without orthostatic hypotension (15 ± 2 vs. 22 ± 2, P = 0.05), correlated negatively with the magnitude of orthostatic fall in systolic pressure (P = 0.04), correlated positively with baroreflex-cardiovagal gain (P = 0.04), fractional increments in plasma norepinephrine levels during orthostasis (P = 0.01), and septal:liver, free wall:liver, and renal cortex:liver ratios of 6-[18F]fluorodopamine-derived radioactivity (P = 0.01, 0.03, 0.05), and were unrelated to ratings of severity of parkinsonism or to putamen:occipital ratios of 6-[18F]fluorodopaderived radioactivity. Interpretation: In PD, olfactory dysfunction is related to orthostatic hypotension, baroreflex failure, and sympathetic noradrenergic denervation.

Autoimmune autonomic ganglionopathy: not just autonomic failure anymore… C. Gibbons, J. Centi, R. Freeman Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA Background: Autoimmune autonomic ganglionopathy (AAG) is a disorder of antibodies to the nicotinic acetylcholine receptor of the autonomic ganglia (ganglionic AChR). Patients present with recurrent syncope, orthostatic hypotension, bowel and bladder hypomotility, pupillary dysfunction, dry mouth and dry eyes. We have observed fluctuating cognitive changes in patients. Objective: To determine the importance of dynamic blood pressure changes and antibody titers on cognition in patients with AAG. Methods: Three antibody positive AAG patients had repeated neuropsychiatric testing in the seated and standing positions (with simultaneous blood pressure recordings) pre- and post-plasma exchange over several months. Tests of attention, short-term memory, working memory and verbal fluency were repeated with AchR antibody titers drawn at each visit.

279 Results: Pre-pheresis cognitive function was impaired, and worsened with standing (P \ 0.05) associated with significant orthostatic hypotension (SBP drop [40 mmHg, P \ 0.01 vs. seated). Post-pheresis there was an improvement in verbal fluency, memory and attention (all P \ 0.05 vs. pre-pheresis seated) with the same blood pressures. Further non-significant cognitive improvements occurred with standing post-pheresis (no accompanying orthostatic blood pressure change). Antibody titers decreased significantly pre- versus post-pheresis (2.68 vs. 0.43 nmol/L, P \ 0.01). Discussion: This pilot study shows acute, short-term effects of blood pressure on cognition, but also highly significant effects of antibody titers on cognitive function independent of blood pressure. In the management of AAG, it is important to consider the role played by blood pressure and antibody titers on cognitive function. The mechanism underlying the relationship between cognition and elevated antibody titers is unknown.

What is the mechanism of non-dipping phenomenon in postural tachycardia syndrome? K. Sato1, L. Diedrich2, I. Biaggioni1, S.R. Raj1, L. Wang3, D. Robertson1, A. Diedrich1 1 Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN, USA; 2 Interventional Pain Center, Department of Anesthesiology, Vanderbilt University, Nashville, TN, USA; 3 Departments of Biostatistics, Vanderbilt University, Nashville, TN, USA Background: We have recently reported a high incidence of ‘‘nondipping’’ (nocturnal drop in systolic blood pressure (SBP)\10% from daytime values) in patients with postural tachycardia syndrome (POTS). The ‘‘non-dipping’’ phenomenon is associated with a poor prognosis in hypertensive patients. The mechanism is unknown in POTS. We hypothesize that non-dipping is associated with autonomic dysfunction in these patients. Methods: We recorded ambulatory BP and heart rate (HR) every 30 min for 24 h in patients with POTS (n = 28 female, age = 33 ± 10 years, BMI 22 ± 7 kg/m2 ) and healthy volunteers (n = 10, female, age = 33 ± 9 years, BMI 23 ± 4 kg/m2 ). Following 3 days of a low-monoamine, caffeine-free diet containing 150 mEq sodium and 70 mEq potassium per day, we collected 12-h urines to measure catecholamines and volume separately during daytime and nighttime. Plasma catecholamines, plasma renin activity (PRA), and aldosterone were measured. Standard autonomic function tests, muscle sympathetic nerve activities (MSNA), and tilt table test were performed. Results: Night-time HR and SBP were higher in POTS (HR: 72 ± 8 vs. 64 ± 9 bpm, P = 0.037, SBP: 101 ± 8 vs. 94 ± 10 mmHg, P = 0.003) although daytime BP and urinary volume were similar. Baseline MSNA was significantly lower in POTS than in healthy (11 ± 2 vs. 20 ± 3 bursts/min; P \ 0.0186) non-dipper POTS (ndPOTS) had lower MSNA than dipper POTS (dPOTS) at 30
tilt (17 ± 3 vs. 29 ± 4 bursts/min; P = 0.052). ndPOTS had significantly less urinary sodium excretion at night than dPOTS (P \ 0.01). Supine PRA (1.6 ± 0.5 vs.1.3 ± 0.2 ng/(ml h); P = 0.55) and aldosterone (9.9 ± 2.2 vs. 7.1 ± 1.3 ng/ml; P = 0.59) were higher in ndPOTS than dPOTS, and night time urinary volume was significantly reduced in ndPOTS (668 ± 57 vs. 924 ± 350 ml, P = 0.029). No significant relationships between autonomic baroreflex function and non-dipping phenomenon were found in POTS.

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280 Conclusions: This study suggests that most POTS patients have diminished diurnal variation of BP possibly due to altered volume regulation and sympathetic control.

Indomethacin rapidly controls tachycardia in postural tachycardia syndrome S.R. Raj, I. Biaggioni, B.K. Black, S. Paranjape, D. Enayat, D. Robertson Vanderbilt University, Nashville, TN, USA Background: Many patients with postural tachycardia syndrome [POTS; heart rate (HR) increase [30 bpm on standing) have low blood volume and possibly inadequate renal sodium retention. Indomethacin is a NSAID that has been recognized to promote fluid retention via renal prostaglandin inhibition. We prospectively tested the hypothesis that indomethacin would decrease tachycardia and improve symptoms in POTS. Methods: Patients with POTS (n = 19; 17 female, 33 ± 2 years) underwent a randomized single-blind crossover trial with oral indomethacin 50 mg and placebo on separate mornings. Patients were studied 2 h after breakfast in a drug-free state. Non-invasive HR and blood pressure (BP) were measured with the patient seated comfortably. At baseline, and hourly for 4 h post-medication, the patients stood for up to 10 min, and their standing HR and BP recorded. Symptoms were self-recorded q2 hourly. Data were analyzed with a repeated measures model with post hoc testing. Data are presented as mean ± SEM. Results: The standing HR decreased more post drug with indomethacin [baseline (B): 117 ± 4 bpm, 4 h: 99 ± 4 bpm) than placebo (B: 118 ± 4 bpm, 4 h: 106 ± 5 bpm; PDRUG = 0.005). Indomethacin also lowered the seated HR (B: 85 ± 3 bpm, 4 h: 73 ± 3 bpm) more than placebo (B: 86 ± 3 bpm, 4 h: 82 ± 2 bpm; PDRUG = 0.009). The decrease in orthostatic tachycardia (stand-sit) was not significant (PDRUG = 0.25). The decreases in both standing and seated HR were different (P \ 0.05) hourly from 2 to 4 h. There was a small non-significant increase in blood pressure. Despite the improvement in HR, indomethacin worsened the symptom burden compared to placebo (4 h: 19 ± 3 vs. 13 ± 3 au; P = 0.014). Conclusions: Indomethacin significantly reduces heart rate acutely in POTS, although it did not improve symptoms. Significant decreases are apparent within 2 h of ingestion, which is faster than one would expect from a renal sodium retention mechanism. These data suggest that suggesting that a non-renal mechanism involving prostaglandin regulation of blood pressure and heart rate may be involved.

Beta blockers and exercise tolerance in postural tachycardia A. Gamboa, L.E. Okamoto, G. Farley, S. Paranjape, B. Black, A. Diedrich, I. Biaggioni Department of Medicine, Vanderbilt University, Nashville, TN, USA Postural tachycardia syndrome (POTS) is a hyperadrenergic disorder characterized by an excessive increase in heart rate upon standing (more that 30 bpm) and extreme orthostatic intolerance. In addition, patients also suffer from varying degrees of physical deconditioning in part due to their profound exercise intolerance while in the upright posture. Propranolol is the most used pharmacological treatment to control tachycardia, but also has the side effect of increasing fatigue. Recently, exercise training has been proposed as pivotal in the treatment of this condition and has the potential to chronically

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Clin Auton Res (2009) 19:275–316 decrease baseline heart rate and improve orthostatic tolerance; however, it is not known if propranolol would impair exercise performance in POTS. We hypothesized that the combined use of propranolol and exercise will result on an additive beneficial effect. In a double-blind randomized placebo controlled study, we enrolled six POTS patients. VO2 was measured on both occasions, on 1 day patients received placebo and the other propranolol 20 mg PO 40 min prior to exercising in a recumbent bike. Resistance was increased by 25 w at 2 min intervals until maximal effort was achieved. Subjects’ baseline oxygen consumption, cardiac output, heart rate and blood pressure were similar in both days. Peak VO2 was statistically higher on the propranolol day (26.4 ± 2.1 and 27.7 ± 2.0 ml/(kg min) for placebo and propranolol respectively, P = 0.03 by Wilcoxon signed rank test) while peak heart rate tended to be slower (173 ± 6 vs. 159 ± 6 bpm for placebo and propranolol respectively, P = 0.21). The anaerobic threshold was not significantly different between days (P = 0.625). These results suggest that propranolol at low doses used to treat POTS patients, does not impair exercise tolerance in this condition, and even provides a marginal beneficial effect.

Familial dysautonomia: a genetic disorder with complete afferent baroreflex failure L. Norcliffe-Kaufmann, F. Axelrod, H. Kaufmann Dysautonomia Research Laboratory, Department of Neurology, New York University School of Medicine, New York, NY, USA Background: In familial dysautonomia (FD), a mutation affecting the protein IKAP prevents the normal embryonic development of specific sensory and autonomic neurons, leading to a complex and poorly understood autonomic phenotype. Methods: To test the hypothesis that baroreflex afference is impaired in FD, we studied the hemodynamic and neuroendocrine responses during baroreflex dependent (i.e., gravitational) and independent (i.e., cognitive/emotional) stimuli in 50 FD patients and compared the results with those of 10 patients with pure autonomic failure, a disorder with selective loss of efferent autonomic neurons and 12 normal controls. Results: Upright tilt markedly lowered blood pressure in pure autonomic failure and in FD, but heart rate increased in pure autonomic failure and decreased in FD. Bradycardia in FD was not prevented by atropine. Head-down tilt increased blood pressure in pure autonomic failure and in FD, but heart rate did not change in pure autonomic failure and increased in FD. The slope of the relationship between blood pressure and heart rate was reduced in pure autonomic failure but was reversed in FD. Vasopressin was released during hypotension in pure autonomic failure but not in FD. Emotional and cognitive stimuli induced little changes in blood pressure and heart rate in pure autonomic failure, but pronounced increases in FD. Conclusion: Patients with FD have a unique autonomic phenotype: they lack afferent baroreflex feedback and their heart rate and blood pressure move in parallel. This phenotype unmasks an important role of IKAP in the development of baroreflex pathways.

Cardiac ectopy in chronic autonomic failure D.S. Goldstein Clinical Neurocardiology Section, CNP, DIR, NINDS, NIH, Bethesda, MD, USA Background: Chronic autonomic failure (CAF), as in Parkinson disease (PD), multiple system atrophy (MSA), and pure autonomic failure (PAF), typically entails baroreflex failure, neurogenic orthostatic hypotension (NOH), and supine hypertension. This

Clin Auton Res (2009) 19:275–316 constellation might predispose to cardiac ectopy, which in turn might predispose to syncope and falls during manipulations decreasing venous return to the heart. This study assessed whether CAF is associated with an increased prevalence of cardiac ectopy. Methods: Recordings lasting C15 min of the electrocardiogram, beatto-beat heart rate, and continuous blood pressure were reviewed from a total of 101 CAF patients (35 PD + NOH, 50 MSA, 16 PAF) and 95 control subjects (43 PD with NOH, 43 non-parkinsonian patients, 9 healthy volunteers). Cardiac ectopy was considered present if there were at least two premature beats or an arrhythmia. Results: Atrial ectopy was found in 74% of patients with PD + NOH, 68% with MSA, and 63% with PAF, prevalences 2–3 times those in PD without NOH (28%, P \ 0.0001) or other controls (24%, P \ 0.0001). Atrial ectopy was related to subject age (P \ 0.0001), supine systolic pressure (P \ 0.0001), and the orthostatic fall in systolic pressure (P = 0.0007) and inversely with baroreflex-cardiovagal gain (P = 0.005) and the orthostatic increment in plasma norepinephrine (P = 0.0004). In 2 PD + NOH patients, atrial ectopy was associated with documented sustained hypotension after the Valsalva maneuver; and in an MSA patient, acute atrial flutter/ fibrillation was associated with sudden loss of consciousness. Interpretation: CAF patients have a relatively high frequency of atrial ectopy, which might interact with baroreflex failure to increase morbidity from orthostatic hypotension.

Treatment with droxidopa—a phase III multinational, placebo-controlled, parallel group, withdrawal-design study in subjects with neurogenic orthostatic hypotension and non-diabetic autonomic neuropathy H. Kaufmann1, C. Mathias2, R. Freeman3, P. Low4, I. Biaggioni5 and the Droxidopa Study Group 1 New York University School of Medicine, New York, NY, USA; 2 Imperial College School of Medicine, London, UK; 3 Beth Israel Deaconess Medical Center, Boston, MA, USA; 4 Mayo Clinic, Rochester, MN, USA; 5 Vanderbilt University, Nashville, TN, USA Background: Neurogenic orthostatic hypotension (NOH) is a disabling feature of autonomic dysfunction that causes dizziness, vision disturbance, fatigue, weakness and loss of consciousness. Deficient norepinephrine release on standing is the underlying cause of NOH. This study evaluated the clinical benefit and effectiveness of droxidopa, a synthetic amino acid that is converted to norepinephrine, in patients with symptomatic NOH. Methods: To date, 67 patients have been enrolled in 55 centers around the world [68% male; age 67 + 11 (mean +SD)]; Parkinson’s disease (39%), multiple system atrophy (29%), pure autonomic failure (23%) and ‘‘other’’ (9%) including 1 dopamine beta-hydroxylase deficiency patient. By June 2009, it is projected that 82 patients will be enrolled. Symptomatic NOH of non-diabetic origin was confirmed during 2-week baseline evaluation. Patients were then titrated with droxidopa in 100 mg T.I.D. increments, from 100 to 600 mg T.I.D., and kept on their individual optimal treatment dose for 1 week. Subsequently, patients were randomized in a double-blinded fashion to either continue droxidopa or receive placebo. Study outcome measures were assessed 2 weeks later. Results: The effectiveness of droxidopa will be discussed regarding its impact on each of 10 components of a clinical orthostatic hypotension questionnaire. Data currently available from the open-label titration phase on the first 46 patients indicates a significant benefit of 4.8 + 2.3 units on the primary outcome of orthostatic dizziness and lightheadedness symptom (item #1 of the orthostatic hypotension questionnaire). This was accompanied by a mean 27 ± 18 mmHg improvement

281 in standing systolic blood pressure. The safety of droxidopa and standing and supine blood pressure and heart rate will be presented. Conclusions: Preliminary analysis, based on assessment during the open label phase of the trial suggests that droxidopa has a positive symptomatic and pressor effect on patients with NOH.

Streeten Travel Fellowship Award L-Dopa induced depression of hypoxic ventilatory drive in Parkinson’s disease C. Noack1, C. Schroeder2, S. Hartmann1, A. Lipp1,2 1 Department of Neurology, Charite´ Virchow Klinikum, Berlin, Germany; 2 CRC, Charite´ Berlin Buch, Berlin, Germany Patients with multiple system atrophy and Lewy body disorders, including Parkinson disease and dementia with Lewy bodies, frequently suffer from sleep apnea and respiratory stridor, eventually causing respiratory failure. Disturbance in central (Benarroch et al. Brain 2007) and peripheral chemosensitive neurons are thought to be involved. Recently, impaired chemosensitivity to hypoxia was reported in PD (Onodera et al. Lancet 2000), although a confounding effect of L-Dopa treatment cannot be ruled out. To assess the impact of L-Dopa therapy on chemoreflex regulation, we studied ventilatory responses and changes in blood pressure and heart rate in seven PD patients in defined OFF and after administration of 200 mg L-Dopa. Hypoxia was induced by step-wise increase of N2-partial pressure and limited to SaO2 of C80%. PetCO2 was clamped at baseline levels to prevent a confounding effect of hypocapnia. Hypercapnia was induced by rebreathing of a hyperoxic gas-mixture (95% O2, 5% CO2) and limited to a PetCO2 B 65 mmHg. Beat-to-beat blood pressure and heart rate were recorded continuously throughout the study. Changes in O2 and CO2 partial pressure and minute ventilation (VE) were continuously recorded on a breath-by-breath basis. Ventilatory responses to hypoxia and hypercapnia are expressed as slope of the regression line relating ventilation to changes in SaO2 and PetCO2, respectively. Administration of 200 mg of L-Dopa induced a dramatic blunting of the ventilatory response to hypoxia in PD patients (OFF: -0.38 ± 0.09; ON: -0.24 ± 0.03; P = 0.002). Ventilatory responses to hypercapnia, however, did not differ significantly with respect to L-Dopa treatment (OFF: 4.00 ± 0.43; ON: -3.85 ± 0.49; P = 0.34). Administration of 200 mg L-Dopa induced a significant reduction of baseline blood pressure (OFF: 143 ± 21, 116 ± 24; P = 0.009) whereas the pressor effect of hypoxia was unaffected by L-Dopa treatment. Our data suggest that L-Dopa directly inhibits peripheral chemoreceptor function in PD. L-Dopa induced baroreflex activation might additionally suppress chemoreflex function, however, preserved ventilatory responses to hypercapnia indicate a minor importance of this pathway.

AAS Travel Award Enhanced SOD activation in the central nervous system and high blood pressure are associated with ACE2 gene deletion in aging mice Xia, Y. Cai, S. Bindom, E. Lazartigues Department of Pharmacology and Experimental Therapeutics, LSU Health Sciences Center, New Orleans, LA, USA We previously showed that paraventricular nucleus (PVN)-targeted angiotensin-converting enzyme 2 (ACE2) gene therapy reversed the Angiotensin-II-mediated increase in oxidative stress in ACE2

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282 knockout (KO) mice. We hypothesized that aging promotes oxidative stress and over-activation of the renin angiotensin system (RAS) in this model. ACE2 KO (12 and 36 weeks old) and control littermates (C57Bl/6 background, n = 8/group) were implanted with telemetry probes for blood pressure (BP) monitoring. Superoxide levels in the brain were determined by dihydroethidium (DHE; 80 lg/kg, intracardiac injection) staining. Superoxide dismutases, SOD 1 and 2, protein expression were determined by western blot. Although BP (98.3 ± 1.3 vs. 98.5 ± 2.2 mmHg) and daily water intake (DWI; 3.4 ± 0.2 vs. 3.1 ± 0.4 ml) were not different between young KO and controls, significant increases were observed in old KO mice compared to controls (102.9 ± 3 vs. 93.5 ± 1.8 mmHg; 4.7 ± 0.4 vs. 3.2 ± 0.3 ml; P \ 0.05). In addition, in contrast to our previous observation showing identical DHE staining in the brain of young mice, old KO mice exhibited higher DHE staining (arbitrary units) in both subfornical organ (3.5 ± 1 vs. 1.0 ± 0.3) and PVN (2.4 ± 0.5 vs. 1.0 ± 0.2) compared to their controls (P \ 0.05). Moreover, upregulated SOD1 (1.6 ± 0.1 vs. 1.0 ± 0.1) and SOD2 (1.5 ± 0.07 vs. 1.0 ± 0.05) expression were observed in the hypothalamus of old KO mice, consistent with higher SOD activity (1,108 ± 197 vs. 616 ± 95 units/mg protein) in this region (P \ 0.05). These data suggest that ACE2 deletion is responsible for an over-activation of the RAS, leading to enhanced oxidative stress in aged mice, associated with an increased SOD expression and activity in brain regions involved in BP regulation. The rise in BP is likely to result partly from a failure of the compensatory increase in SOD. Our data support an antioxidant effect of ACE2 in the brain and a potential for this carboxypeptidase as a new target in the treatment of hypertension and other cardiovascular diseases.

FMS/Penez-Wesseling Award Norepinephrine transporter blockade and cholinesterase inhibition have a synergistic effect on blood pressure in autonomic failure L.E. Okamoto, A. Gamboa, C. Shibao, B.K. Black, S.R. Raj, D. Robertson, I. Biaggioni Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University, Nashville, TN, USA Patients with autonomic failure (AF) are characterized by disabling orthostatic hypotension due to impaired sympathetic activity. Norepinephrine transporter (NET) blockade with atomoxetine raises blood pressure in AF by increasing synaptic norepinephrine (NE) concentrations in peripheral sympathetic neurons. This effect, however, requires tonic release of NE. We tested the hypothesis that the pressor effect of NET blockade with atomoxetine is potentiated by the cholinesterase inhibitor pyridostigmine, which improves ganglionic cholinergic neurotransmission thus increasing residual sympathetic outflow. We studied eleven patients with severe AF refractory to therapy (age 69 ± 3 years, 7 males). At baseline, blood pressure decreased from 137 ± 10/81 ± 5 supine to 86 ± 7/55 ± 7 mmHg standing without an appropriate increase in heart rate (73 ± 2 to 90 ± 5 bpm). Patients were given either placebo, pyridostigmine 60 mg, atomoxetine 18 mg or the combination of pyridostigmine and atomoxetine on separate days in a single blind, crossover study. Neither pyridostigmine nor atomoxetine produced a significant increase in systolic blood pressure (SBP) compared to placebo. Mean seated SBP from 30 to 60 min post drug was 96 ± 6 and 100 ± 6 for pyridostigmine and atomoxetine respectively, whereas it was 101 ± 5 mmHg for placebo (P [ 0.05). Only the combination of atomoxetine with pyridostigmine increased SBP. The maximal increase in SBP seen with this combination was 27 ± 9 mmHg. We conclude that pyridostigmine potentiates the pressor effect of NET

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Clin Auton Res (2009) 19:275–316 blockade in patients with autonomic failure. This pharmacologic approach could be useful in patients with autonomic failure in whom orthostatic hypotension is refractory to conventional treatment.

FMS/Penez-Wesseling Award Autonomic and exercise testing in healthy adults before and after endoscopic thoracic sympathotomy for hyperhidrosis E.A. Wehrwein1, R.L. Elvebak1, R.D. Fealey2, J.L. Atkinson3, N. Charkoudian4, J.H. Eisenach1 1 Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA; 2 Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA; 3 Department of Neurology, Mayo Clinic, Rochester, MN, USA; 4 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA Severe palmar hyperhidrosis and medically refractory long-QT syndrome have traditionally been treated using T2–T4 ganglion excision. However, surgery for hyperhidrosis at our institution involves a sympathetic chain ablation between the stellate and T2 sympathetic ganglia aimed to reduce postoperative compensatory sweating. The long-term autonomic and cardiovascular sequelae of this ganglionsparing technique are unknown. Because denervation involves sympathetic cardio-accelerator fibers, our purpose was to compare pre- versus post-op baroreflex control of heart period, hemodynamic responses to exercise, and QT interval on resting ECG. Of 22 adults with severe palmar hyperhidrosis who received pre-op testing of ECG, two modified Oxfords (IV bolus of nitroprusside + phenylephrine; finometer for BP), and cycle exercise for VO2 max, 17 completed the trials 1–12 months post-op, and 5 were unable to return due to geographic constraints. Of the 17, mean age ± SE was 25 ± 2 years, BMI 23 ± 1, and 12 were female. All reported palmar anhidrosis with minimal or non-bothersome compensatory hidrosis of the trunk. Compared to pre-op, resting HR and QT interval were unchanged. RRI/SBP baroslopes were unchanged (13.5 ± 1.4 vs. 13.4 ± 1.4 ms/mmHg). Exercise duration and VO2 max were unchanged, while the maximal HR response to exercise was reduced by 6% (193 ± 3 vs. 182 ± 3 bpm, P = 0.002). We conclude that sympathotomy surgery has no influence on resting hemodynamics, baroreflex control of RRI, or QT interval. The blunted maximal HR response to exercise is consistent with a ‘‘beta-blocker’’ effect of sympathetic denervation but appears to have minimal consequences for exercise capacity. Funding: NS-32352, CTSA RR-024150.

Friday, November 13, 2009 Oral Presentations Spontaneous baroreflex during salt-loading in young hypertensive men I.V. Emelyanov1, A.O. Konradi1, A.Y. Bagrov2, E.V.Shlyakhto1 1 Federal Centre of Heart, Blood and Endocrinology, SaintPetersburg, Russian Federation; 2 National Institute on Aging, NIH, Baltimore, MD, USA Objective: Previous studies have documented that impairment of baroreflex response to chronic salt loading is implicated in salt sensitivity of blood pressure (BP). In the present study, we investigated

Clin Auton Res (2009) 19:275–316 changes of baroreflex sensitivity and BP during acute salt-loading test in hypertensive male patients. Design and methods: We examined 12 young males from 19 to 35 years (mean age 22.5 ± 4.7 years) with newly diagnosed essential hypertension (HT) and without antihypertensive therapy. The salt loading was performed according to standard protocol (i.v. infusion of 2,000 mL saline for 4 h). The Finometer Pro device (Amsterdam, Netherlands) was used for beat-to-beat continuous BP registration. Baroreflex sensitivity (BRS) was calculated by sequence technique. Hourly BP and BRS values were analyzed. Results: A significant increase in BP was observed within 2 h of NaCl loading (systolic BP: 149 ± 4 vs. 137 ± 3 mmHg at baseline, P \ 0.05; Diastolic BP: 89 ± 3 vs. 82 ± 2 mmHg at baseline). At the end of the test, BP remained elevated as compared to baseline values (148 ± 4/91 ± 3 mmHg; P \ 0.05). BRS increased from 5.53 ± 0.97 to 6.35 ± 0.87 mmHg/min (P \ 0.05) within 1 h of NaCl loading and remained elevated throughout the experiment. Delta BRS (1 h vs. baseline) BP exhibited an inverse correlation (r = -0.58, P \ 0.05) with the delta systolic BP (3 h vs. baseline). Conclusions: Present results indicate that during acute salt loading of hypertensive patients BP response is accompanied by an increase in spontaneous baroreflex. A negative relationship between changes in BP and BRS suggests that an impaired baroreflex aggravates pressor response to NaCl loading.

Cardiac sympathetic denervation does not alter development or maintenance of DOCA-salt hypertension E.A. Wehrwein2,3, M. Yoshimoto1, P. Gusman1, D.L. Kreulen2, J.W. Osborn1 1 Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA; 2 Department of Physiology, Michigan State University, East Lansing, MI, USA; 3 Mayo Clinic, Rochester, MN, USA, Human and Integrative Physiology/Anesthesia Research, Rochester, MN, USA Cardiac norepinephrine spillover is increased in some forms of human essential hypertension suggesting that increased sympathetic nerve activity (SNA) to the heart contributes to pathogenesis of this disease. Neurogenic hypertension produced in the rat by administration of deoxycorticosterone acetate and a high salt intake (DOCA-salt) may also be associated with increased cardiac SNA. We hypothesized that cardiac denervation by stellate ganglionectomy (SGX) would attenuate DOCA-salt hypertension in the rat. Experiments were conducted in two strains of Sprague Dawley rats since previous studies reported bradycardia (Charles River Sprague Dawley; CR-SD) or tachycardia (Sasco Sprague Dawley; SA-SD) in DOCA-salt hypertension. Uninephrectomized rats underwent SGX or Sham surgery, were instrumented for telemetric monitoring of mean arterial pressure (MAP) and heart rate (HR), and allowed 10 days to recover. MAP and HR were measured continuously during the 30 day protocol. On Day 0 rats were switched to a 0.9% NaCl/0.2% KCl drinking solution and on day 5 DOCA (50 mg/rat, sc) was implanted. Baseline MAP (96 ± 2 mmHg) and HR (377 ± 7 bpm) in SGX CR-SD rats (n = 7) were significantly lower compared to Sham CR-SD rats (102 ± 3 and 432 ± 7, n = 9). However, by the end of the DOCA-salt period, MAP was similar in SGX CR-SD (140 ± 5 mmHg) and Sham CRSD (135 ± 5 mmHg) rats. In SA-SD rats, baseline MAP was not different between SGX (n = 8) and Sham (n = 7) rats but HR was (428 ± 8 vs. 371 ± 5). By the end of the DOCA-salt protocol, MAP was similar in SGX SA-SD (152 + 8 mmHg) and Sham SA-SD (155 + 10 mmHg) rats. We conclude that cardiac sympathetic nerves

283 do not play a vital role in the pathogenesis of DOCA-salt hypertension in the rat. American Heart Association Predoctoral Fellowship, T32 DK07352, PO1HL70687, and NHLBI R01 HL64176.

Spinophilin affects central angiotensin II- and L-NAME induced changes in blood pressure regulation in mice A.C. da Costa-Goncalves1, M.A. Peliky Fontes2, J. Janke3, J. Tank4, R. Plehm5, J. Jordan4, F.C. Luft3,5, V. Gross5 1 Leibnitz Institut for Molecular Pharmacology, Berlin, Germany; 2 Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil; 3 Experimental and Clinical Research Center, Berlin, Germany; 4 Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany; 5 Max Delbru¨ck Center for Molecular Medicine, Berlin, Germany Angiotensin II (AngII) and nitric oxide (NO) regulate blood pressure (BP) including the sympathetic tone. Given the fact that the absence of spinophilin (SPL) results in BP increase via sympathetic activation, we investigated whether SPL plays a role in central BP regulation via Ang II and NO. We measured arterial BP and heart rate using telemetry and assessed autonomic nervous system functions in SPL-/- and SPL+/+ mice treated chronically with: (1) Nx-nitro-L-arginine methyl ester (5 mg L-NAME/10 ml tap water), (2) Ang II [0.5 mg/(kg day)] and (3) the Ang II type 1 receptor (AT1-R) antagonist valsartan [50 mg/(kg day)]. L-NAME treatment increased BP stronger in SPL-/- than in SPL+/+ at day (11.5 ± 1.3 vs. 6.8 ± 1.4 mmHg) and at night (11.2 ± 1.6 vs. 8.7 ± 0.8 mmHg), whereas in Ang II-treated mice BP increased only during day time stronger in SPL-/- (19.2 ± 0.8 vs. 13.5 ± 1.6 mmHg). Valsartan effect on BP was higher in SPL-/than in SPL+/+. Intracerebroventricular administration of L-NAME and Ang II caused stronger rise in BP in SPL-/- than in SPL+/+. Interestingly, Ang II but not L-NAME induced a tendency to attenuate SPL gene expression. However, expressions of AT1-R, AT2-R, nNOS and eNOS were not different between SPL-/- and SPL+/+. Ang II treatment increased the magnitudes of BP decreases after trimethaphane in SPL-/- and SPL+/+, whereby Ang II-SPL-/- displayed a stronger decrease in BP than Ang IISPL+/+. In L-NAME-treated SPL-/- BP decreased also stronger after trimethaphane without changing the magnitude. Our data suggest that the SPL gene is involved in L-NAME and Ang IIdependent increase of BP, whereby the mechanisms are different. SPL-deficiency promotes Ang II-dependent increase of central sympathetic outflow. However, changes in sympathetic tone are not involved in NO-dependent BP changes in SPL-/- mice.

High NIHSS scores after stroke onset suggest increased sympathetic risk M.J. Hilz1,2, H. Marthol1, P. De Fina3, S. Schwab1 1 Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany; 2 Departments of Neurology, Medicine, and Psychiatry, New York University, New York, NY, USA; 3 International Brain Research Foundation, Edison, NJ, USA Background: Acute stroke is frequently associated with cardiac complications due to central autonomic network dysfunction (CAND) (Hilz in Schwab Stroke 39:2421–2422, 2008). CAND severity probably correlates with stroke severity.

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284 Objective: To evaluate whether clinical stroke severity, determined by the NIHSS, correlates with CAND alteration. Patients and methods: In 20 patients (8 women, mean age 74 ± 10 years) with middle cerebral artery ischemic stroke (10 left-, 10 right-hemispheric), we determined NIHSS within 50– 540 min (mean 226 ± 162 min) after stroke onset, and monitored heart rate as R–R intervals (RRI). We calculated spectral powers of RRI oscillations in the parasympathetically mediated, high (RRIHF: 0.04–0.15 Hz) and mainly sympathetically mediated low (RRILF: 0.15–0.5 Hz) frequency bands using trigonometric regressive spectral analysis. We determined the LF/HF-ratio reflecting sympathovagal balance, and the sum of LF- and HF-powers as approximation of total power of autonomic RRI modulation. NIHSS scores were correlated with LF-, HF-, total powers and LF/ HF-ratios (Pearson R; significance: P \ 0.05). Results: Patients had NIHSS scores of 0–21 (median: 6; lower quartile: 3; upper quartile: 9.75), and RRIs of 804.2 ± 181.5 ms, powers of RRI-LF at 144.4 ± 145.4 ms2, RRI-HF at 69.6 ± 59.5 ms2; RRItotal powers were 223.4 ± 188.1 ms2, LF/HF-ratios were 3.7 ± 4.4. There was no correlation between NIHSS scores and RRI-LF-powers. However, correlations were significant between NIHSS scores and RRIs (R = -0.459; P = 0.042), RRI-HF-powers (R = -0.635; P = 0.003), LF/HF-ratios (R = 0.744, P = 0.000), and total powers (R = -0.452, P = 0.045). Conclusion: Higher NIHSS values correlated with more prominent increases in sympathetic, decreases in parasympathetic and total autonomic cardiac modulation. Higher sympathetic tone with less parasympathetic buffering and reduced overall heart rate modulation increase the risk of cardiac complications. Thus, our data suggest that high NIHSS scores indicate a high risk of sympathetically mediated cardiac complications. Acknowledgement: The study was partially supported by the International Brain Research Foundation, IBRF, Inc., Edison, NJ, USA.

Reduced parasympathetic heart rate reserve in healthy middle-aged subjects J. Tank1, K. Heusser1, A. Diedrich2, F.C. Luft3, J. Jordan1 1 Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany; 2 Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA; 3 Experimental Clinical Research Center, Medical Faculty of the Charite´ and HELIOS Klinikum, Berlin, Germany Parasympathetic heart rate regulation deteriorates with increasing age through unknown mechanisms. Baroreflex loading during alpha-2 adrenoreceptor stimulation provides a graded increase in parasympathetic activity and therefore may distinguish between functional and structural causes. We applied this approach in nine younger (6 men, 3 women, 31 ± 2 years, 24 ± 1 kg/m2 ) and nine middle-aged (2 women and 7 men, 49 ± 2 years, 27 ± 2 kg/m2 ) healthy subjects. Incremental intravenous phenylephrine infusions with and without clonidine (1–2 lg/kg) were given. We determined heart rate (HR), beat-by-beat blood pressure (BP), HR-variability (HRV), and BP-variability (BPV). Supine BP and HR were similar in both groups. Before clonidine infusion, phenylephrine elicited a similar pressor response in both groups. Baroreflex loading with phenylephrine increased mean RR interval to a maximum of 1,109 ± 60 ms in younger and 1,163 ± 67 ms in middle-aged subjects (ns). Pharmacological baroreflex curves were similar in

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Clin Auton Res (2009) 19:275–316 both groups. Baroreflex loading augmented HRV in both groups. The response was less pronounced in older subjects. With clonidine infusion, the decrease in BP and HR was similar in both groups. The maximal change in systolic BP with phenylephrine after clonidine infusion was 17 ± 2 mmHg in younger and 28 ± 3 mmHg in older subjects (P \ 0.05). Baroreflex loading with phenylephrine during clonidine increased mean RR interval to a maximum of 1,357 ± 55 ms in younger and 1,196 ± 50 ms in older subjects (P \ 0.05). The shift of the baroreflex heart rate curve during clonidine infusion to lower blood pressure and heart rate values was much more pronounced in younger subjects. Baroreflex loading during clonidine greatly increased heart rate variability in younger subjects and to a lesser degree in older subjects (P \ 0.05). We conclude that baroreflex loading during alpha-2 adrenoreceptor stimulation unmasks impaired parasympathetic heart rate reserve in middle-aged, but otherwise healthy subjects. The finding is consistent with a structural cause of the age-associated decline in parasympathetic heart rate control.

Sympathoinhibitory actions of the urocortin peptides suggest therapeutic potential in acute cardiac injury C.J. Charles, D.L. Jardine, M.T. Rademaker, A.M. Richards Christchurch Cardioendocrine Research Group, University of Otago, Christchurch, New Zealand Using a model of cardiac sympathetic nerve activity (CSNA) recordings in sheep, we have demonstrated for the first time, in a conscious animal model, that CSNA increases rapidly during the first 60 min following experimental myocardial infarction (MI), peaking at 2 h and remaining elevated for at least 4 days [1]. Furthermore, CSNA is increased in sheep who suffer sudden cardiac death in the first hours post-MI compared to those surviving at least 7 days [2]. We have previously reported that all three members of the urocortin (Ucn) family, Ucn1 [3], Ucn2 [4], and Ucn3 [5] have profound and sustained beneficial cardiovascular, hormonal and renal effects - including reductions in cardiac preload and afterload, improvements in cardiac output, inhibition of a spectrum of deleterious vasoconstrictor/volume-retaining factors, and augmentation of renal function in an ovine pacing-induced model of heart failure. We have now studied the effect of Ucn1 [6] and Ucn2 on CSNA in conscious sheep. Ucn1 (at doses both above and below the threshold inducing haemodynamic effects) significantly inhibited CSNA. Ucn2 induced a biphasic response in CSNA burst frequency with a brief initial rise (when arterial pressure was reduced) followed by a sustained fall. All other indices of CSNA showed sustained dose-dependent reductions. Inhibition of CSNA occurred despite a presumed generalised baroreflex-activation of vascular and possibly other sites of SNA as reflected in transient increases in plasma catecholamines. These are the first studies to report the effects of the Ucn’s on SNA and demonstrate potent inhibition of sympathetic traffic to the heart. A lack of stimulation or active suppression of CSNA is a desirable characteristic of candidate treatments in acute and chronic cardiac injury. Thus, the Ucn’s warrant further investigation as novel therapeutic agents post-MI. (1) Jardine et al. in J Physiology 565:325–333, 2005, (2) Jardine et al. in Am J Physiol 293:H433– H439, 2007, (3) Rademaker et al. in JACC 40:1495–1505, 2002, (4) Rademaker et al. in Circulation 112:3624–3632, 2005, (5) Rademaker et al. in Eur Heart J 27:2088–2098, 2006, (6) Charles et al. in J Hypertension 26:53–60, 2008.

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Concurrent recording of spontaneous muscle sympathetic nerve activity and whole-brain fMRI signal intensity: ‘real-time’ imaging of cardiovascular control in awake human subjects V.G. Macefield1,2, C. James1, L.A. Henderson3 1 School of Medicine, University of Western Sydney, Sydney, Australia; 2 Prince of Wales Medical Research Institute, Sydney, Australia; 3 Department of Anatomy and Histology, University of Sydney, Australia Introduction: We have recently demonstrated that it is possible to record spontaneous MSNA, via tungsten microelectrodes inserted into a peripheral nerve, at the same time as performing functional magnetic resonance imaging (fMRI) of the brainstem in awake human subjects. We used this approach to functionally identify the operation of the medullary circuitry involved in spontaneous fluctuations in MSNA. In the present study, we attempted to identify other areas within the brain that may contribute to the generation of spontaneous MSNA at rest. Methods: MSNA was recorded from the common peroneal nerve in six experiments in five subjects. Gradient echo, echo-planar fMRI was performed using a 3T scanner (Philips Achieva). 200 volumes (46 axial slices, TR = 8 s, TE = 40 ms, flip angle = 90
, raw voxel size = 1.5 mm3 ) were collected in a 4 s-ON, 4 s-OFF protocol. Total sympathetic burst amplitudes were measured from the RMS-processed mean voltage amplitude during the 4 s period between scans. Blood oxygen level dependent (BOLD) changes in brainstem signal intensity (SPM5: fixed effects, minimum cluster size 10 voxels, corrected false discovery rate P \ 0.005) were measured during the subsequent 4 s period to take into account the +5 s neurovascular coupling delay and the -1 s required for conduction of the sympathetic bursts from the brain to the peripheral recording site. Results: MSNA was positively correlated to signal intensity in the right prefrontal cortex, the right perigenual anterior cingulate cortex and the right amygdala. Conclusions: In addition to the bilateral brainstem regions we had previously identified, we have now shown that neuronal activity within three regions of the forebrain covaries with fluctuations in spontaneous MSNA, suggesting that activity within the right prefrontal cortex, the right perigenual anterior cingulate cortex and the right amygdala contributes to ongoing control of blood pressure in awake human subjects at rest.

Unique sympathetic recruitment patterns by different reflex pathways in humans C. Ozan Tan1,2, J.A. Taylor1,2 1 Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA; 2 Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, MA, USA Animal research shows that sympathetic nerve fibers demonstrate varied responses to different reflex activations. The number and pattern of fiber firing, in turn, may have a substantial effect on vasoconstrictor responses. Although the discharge behavior of single sympathetic fibers has been described in humans, multi-fiber recordings are required to fully elucidate patterns of sympathetic activation to various sympathoexcitatory reflexes. Since it is not feasible to dissect and record simultaneously from several sympathetic fibers in humans, innovative approaches are necessary to discern response patterns from multi-fiber recordings. We obtained

285 multi-fiber sympathetic recordings in five volunteers during supine rest, and during activation of the exercise pressor reflex (isometric handgrip to fatigue), the metaboreflex (3 min of post-exercise ischemia), the nociceptive reflex (3 min of cold pressor), and baroreflex unloading (10 min of 30
upright tilt). We used our recently developed method to identify individual spikes, and classified sympathetic activity based on action potential morphologies. Three to five unique action potential morphologies (i.e., distinct fiber types) were consistently identified within each individual recording. Each unique morphology was consistent with the prior observations from single-fiber recordings, and was reproducible across individuals (r = 0.83 + 0.14 {SD}). Hemodynamic and overall multi-fiber sympathetic responses to each reflex activation were prototypical. Strikingly, however, the increase in overall sympathetic activity during cold pressor and post-exercise ischemia was brought about by recruitment of specific groups of fibers that are mostly silent during supine rest or upright tilt. In contrast, some sympathetic fibers that were active during supine rest and upright tilt were inhibited during cold pressor and post-exercise ischemia. Our results suggest distinguishable patterns of fiber recruitment during activation of different reflex pathways in humans. Further work is needed to address within-individual reproducibility of these distinct firing patterns and whether these patterns are related to different vasoconstriction responses.

Effects of oral contraceptives on sympathetic neural responses to orthostatic stress in young, healthy women J.R. Carter, J.C. Klein, C.E. Schwartz Department of Exercise Science, Health and Physical Education Michigan Technological University Houghton, MI, USA Two recent studies (Fu et al. in J Physiol, 2009; Carter et al. in Am J Physiol Endocrinol Metab, 2009) have reported that the menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women. The purpose of the present study was to determine if oral contraceptives (OC) influence sympathetic neural activation during an orthostatic challenge. Based on evidence that sympathetic baroreflex sensitivity is increased during the ‘‘low hormone’’ (LH) phase (i.e., placebo pills) in women taking OC (Minson et al. in Circulation, 2000), we hypothesized an augmented MSNA response to orthostatic stress during the LH phase. Muscle sympathetic nerve activity (MSNA), mean arterial pressure (MAP), and heart rate (HR) were recorded during progressive LBNP (-5, -10, -15, -20, -30, and -40 mmHg; 3 min per stage) in 12 healthy women taking OC (age 22 ± 1 years). Subjects were examined twice, once during the LH phase and once approximately 3 weeks after LH during the ‘‘high hormone’’ (HH) phase (randomized order). Plasma estradiol (43 ± 7 vs. 28 ± 4 pg/ml) and progesterone (1.3 ± 0.1 vs. 1.5 ± 0.2 ng/ml) were not different between LH and HH phases. Resting MSNA (10 ± 2 vs. 13 ± 2 bursts/min), MAP (85 ± 3 vs. 84 ± 3 mmHg), and HR (62 ± 2 vs. 65 ± 3 beats/min) were not different between phases. MSNA and HR increased during progressive LBNP (P \ 0.001), and these increases were similar between phases. Progressive LBNP did not change MAP during either phase. Our results demonstrate that oral contraceptives do not alter cardiovascular and sympathetic neural responses to an orthostatic challenge in young, healthy women. These findings, taken together with recent data from eumenorrheic women, suggest that hormonal fluctuations associated with the menstrual cycle contribute importantly to patterns of sympathoexcitation during an orthostatic stress.

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Effects of aerobic exercise training on sympathetic and renal responses to mental stress in humans C.A. Ray1, J.R. Carter2 Heart and Vascular Institute, Pennsylvania State College of Medicine, Hershey, PA, USA; 2 Department of Exercise Science, Health and Physical Education, Michigan Technological University, Houghton, MI, USA

1

The effects of aerobic exercise training on muscle sympathetic nerve activity (MSNA) and renal vascular responses to mental stress (MS) have not been determined in humans. We hypothesized that aerobic exercise training would reduce MSNA and renal vasoconstriction during mental stress. MSNA, mean arterial pressure (MAP), heart rate (HR), renal blood flow velocity (RBFV), and peak oxygen uptake (VO2peak) were recorded in 23 healthy adults. Fourteen subjects participated in 8 weeks of aerobic exercise training (ET), while nine subjects served as sedentary controls (CON). ET significantly increased VO2peak (D18 ± 1%; P \ 0.001) and decreased RBFV at rest (60 ± 4 to 48 ± 3 cm/s; P \ 0.01), while CON did not alter VO2peak or RBFV at rest. ET did not alter resting MSNA (11 ± 1 to 9 ± 1 bursts/min), MAP (84 ± 2 to 83 ± 2 mmHg), and these findings were similar in the CON group. MS elicited similar increases in MSNA (*D2 bursts/min; P \ 0.05), MAP (*D155 mmHg; P \ 0.001), and HR (*D20 beats/min; P \ 0.001) before and after ET, and responses were not different between ET and CON. Likewise, MS elicited similar decreases in RBFV and renal vascular conductance before and after ET, and responses were not different between ET and CON. Perceived stress levels during MS were similar before and after the 8 wk study in both ET and CON. In conclusion, ET does not alter MSNA and renal vascular responses to mental stress in healthy humans.

Relationship between sympathetic activity and pain intensity in fibromyalgia F. Barbic1, A. Diana2, F. Casella1, F. Perego3, M. Borella4, F. Dipaola5, G. Costantino4, P. Longhi1, P. Rubin1, R. Furlan1,6 1 Medicina Generale Ospedale ‘‘Bolognini’’, Seriate (BG); Medicina Generale Ospedali; 2 Tradate; 3 IIIa e; 4 IIa Ospedale Sacco, Milano; 5 Sesto S. Giovanni; Medicina; 6 Universita` Studi, Milano, Italy Fibromyalgia (FM) is a chronic syndrome characterized by widespread musculoskeletal pain and discomfort on palpation of specific tender points. Cardiovascular autonomic abnormalities, consistent with a sympathetic overactivity, have been suggested by clinical studies. In addition, a potential role of an exaggerated neural sympathetic activation in generating and sustaining FM chronic pain has been hypothesized by pharmacological sympathetic blockade. It is unknown whether a direct relationship exists between the amount of cardiovascular sympathetic activity and the magnitude of pain. Twenty-five patients (23 female, age 44 ± 2 years) with FM, underwent electrocardiogram, beat by beat blood pressure, respiratory activity and efferent post-ganglionic sympathetic activity (Muscle Sympathetic Nerve Activity, MSNA) recordings at rest. Sympathetic activity was assessed by MSNA burst rate and the marker of cardiac sympathovagal balance LF/HF, obtained by spectrum analysis of heart rate (HR) variability. Pain severity was estimated by a 100 mm visual analogical scale (VAS), ranging from 0 to 100. A score of 100 corresponded to the worst pain. At rest, HR was 73 ± 2 b/min, SAP 126 ± 4 mmHg, DAP

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Clin Auton Res (2009) 19:275–316 82 ± 3 mmHg, respiratory rate 17 ± 1 breaths/min. The index LF/HF was 3.8 ± 0.6 and MSNA 22 ± 1 bursts/min. VAS was 63 ± 3 mm. No correlation was found between VAS and heart rate. Linear positive correlations were observed between VAS and LF/HF (r2 0.18; P = 0.03) and VAS and MSNA burst rate (r2 0.29; P = 0.02). Thus, in patients with FM, the higher the overall cardiovascular sympathetic activity, the higher the musculoskeletal pain intensity. This suggests a potential role of the autonomic profile in modulating pain intensity.

Sympathetic neural activity and lipolysis T.B. Curry1,2, H.M. Tonyan1, M.J. Joyner1,2, J.M. Miles3, N. Charkoudian2 1 Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA; 2 Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA; 3 Division of Endocrinology, Mayo Clinic, Rochester, MN, USA Introduction: Obesity has been associated with increased muscle sympathetic nerve activity (MSNA) and disorders of lipid metabolism as well as decreased adrenergic responsiveness. We hypothesized that muscle sympathetic nervous system activity (MSNA) would be associated with greater levels of free fatty acids (FFA) and a decreased lipolytic response to epinephrine. Methods: 16 individuals (14 F/2 M, age = 34 ± 8.2, wt = 93 ± 23.8,% body fat = 44.5 ± 12.5) underwent measurements of MSNA with microneurography of the peroneal nerve and of lipolysis with 3Hpalmitate during an epinephrine infusion (10 ng kg FFM-1 min-1 ). Results: Data are presented as mean ± SD. Resting MSNA was 31.7 ± 14.9 bursts/100 heart beats, (21.1 ± 10.6 bursts/min). Fasting FFA = 444.7 ± 141.4 and FFA increased to 713.4 ± 239.1 during epi (P \ 0.05). The area under the curve of the rate of appearance of FFA (Ra-AUC) was 274.8 ± 90.3. No relationship was found between resting MSNA and fasting FFA, the change in FFA during epinephrine infusion, or Ra-AUC. Discussion: Our preliminary data do not support our hypothesis that epinephrine-stimulated lipolysis is related to sympathetic activity. Despite the known presence of beta-adrenergic receptors on adipose tissue and effect of epinephrine on increasing lipolysis, the regulation of the magnitude of the lipolytic response to adrenergic agonists appears to be regulated by other mechanisms. Conclusions: Resting MSNA does not appear to be related to adipose tissue catecholamine sensitivity. Further research is needed to determine if there are differences between lean and obese individuals or if body fat distribution alters this relationship.

Saturday, November 14, 2009 Oral Presentations Contribution of cardiac output and sympathetic vasoconstrictor activity to vasovagal syncope evoked by tilt testing B. Verheyden1, Q. Fu2,3, W. Wieling4, B. Levine2,3 1 Laboratory of Experimental Cardiology, University Hospital Gasthuisberg, Leuven, Belgium; 2 Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX, USA; 3 The UT Southwestern Medical Center at Dallas, Dallas, TX, USA; 4 Department of Internal Medicine, Syncope Unit, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands

Clin Auton Res (2009) 19:275–316 In contrast to the traditional model of a decrease in systemic vascular resistance (SVR) leading to orthostatic reflex fainting, recent studies demonstrate that the initial fall in blood pressure (BP) is mainly driven by a fall in cardiac output (CO). The purpose of this study was to investigate the contribution of sympathetic neural withdrawal to the genesis of vasovagal hypotension. We studied retrospectively 26 subjects (4 men and 22 women, age range 16–50) who had no previous history of syncope but did have presyncopal episodes during 45 min 60
upright tilt. Muscle sympathetic nerve activity (MSNA), heart rate (HR), and reconstructed brachial BP were recorded continuously, while beat-to-beat stroke volume (SV) was calculated by advanced pulse contour analysis, calibrated by the acetylene rebreathing technique. In all subjects, BP decreased progressively and then rapidly 60 and 20 s prior to presyncope. Hypotension was mediated by a marked drop in CO in almost all subjects, accompanied by a decreased SVR in 16 of them (62%, Group A). In 10 subjects, SVR was well maintained until presyncope (38%, Group B). Cardiac index tended to be lower [1.82 ± 0.54 L/(min m2 ) vs. 2.14 ± 0.34, P = 0.08], while SVR appeared to be greater (1.28 ± 0.87 MU vs. 0.91 ± 0.23, P = 0.12) in group B than group A at the moment of presyncope. The steeper fall in CO in Group B was due to a steeper decrease in HR rather than in SV. On average in all subjects, MSNA decreased rapidly 20 s prior to presyncope, but this was not related to changes in SVR (r = 0.02; P = 0.98). These data suggest that a fall in CO is the main determinant of hypotension prior to presyncope, with coincident vasodilatation in a large subset. The observed dissociation between MSNA and SVR during presyncope challenges the traditional concept of decreased sympathetic vasoconstrictor activity underlying reflex fainting in upright humans.

Increased phase synchronization in syncope A.J. Ocon1, D. Clark1, I. Taneja2,3, M. Medow1,2, J.M. Stewart1,2,3 1 Department of Physiology, New York Medical College, Hawthorne, NY, USA; 2 Department of Pediatrics, New York Medical College, Hawthorne, NY, USA; 3 Department of Medicine, New York Medical College, Hawthorne, NY, USA Cerebral autoregulation is the intrinsic ability of the cerebral circulation to maintain blood flow when blood pressure changes. This implies reduced synchronization of cerebral blood flow (CBF) to arterial blood pressure (AP). However, oscillatory AP and CBF changes can synchronize phase and frequency through nonlinear interactions. Such nonlinear conditions exist during simple vasovagal syncope which is also a time dependent, non-stationary process poorly amenable to linear transfer function analysis. Therefore, we studied 12 fainters and 12 healthy volunteers, 15–25 years, using phase synchronization methods. We constructed complex analytic signals using the Hilbert transform of mean AP and CBF sampled at 200 Hz and bandpass filtered 0.01–0.5 Hz. Phase was estimated from complex signals resampled at 2 Hz. The phase difference A and a phase synchronization index c(t) = |\E^(IA(T))[| were calculated. c(t) ranges from 0 to 1, where 1 indicates perfect phase alignment and synchronization. Even at supine rest, c varied quasi-periodically implying intermittent changes in autoregulation. Average c when supine in fainters was 0.52 ± 0.03 which was similar to control 0.57 ± 0.02, as were maxima (0.89 ± 0.03 vs. 0.94 ± 0.01) and minima (0.06 ± 0.01 vs. 0.11 ± 0.02). When tilted upright to 70
, similar increases in average c were obtained (0.61 ± 0.02 vs. 0.60 ± 0.03). However, time dependence was radically altered: steady variation in c continued throughout tilt in control subjects, while fainters demonstrated an initial variation followed by profoundly decreased c to 0.23 ± 0.06, P \ 0.001, at 119 ± 16 s prior to faint, followed by an increase in c to a maximum (0.96 ± 0.02,

287 P \ 0.001), when autoregulation appeared absent and fainting supervened. We conclude that syncope subjects exhibit initial autoregulation that becomes ineffective approximately 2 min prior to faint and ultimately fails to maintain adequate cerebral perfusion at faint.

Association between oscillations in cerebral blood velocity and sympathetic activity C.A. Rickards1,2, K.L. Ryan1, V.A. Convertino1 1 US Army Institute of Surgical Research, Fort Sam Houston, TX, USA; 2 Department of Health and Kinesiology, University of Texas at San Antonio, TX, USA Higher oscillations in cerebral blood velocity (CBV) and arterial pressure (AP) are associated with delayed onset of symptoms and increased tolerance to central hypovolemia. While previous studies have shown that AP oscillations are mediated by the sympathetic nervous system, the mechanism responsible for oscillations in CBV is unclear. We hypothesized that oscillations in CBV would also be associated with sympathetic nervous system activity. Eight subjects were exposed to progressive lower body negative pressure (LBNP) until the presence of presyncopal symptoms. CBV was measured at the middle cerebral artery by transcranial Doppler, arterial pressure (AP) was measured via finger photoplethysmography, and muscle sympathetic nerve activity (MSNA) was measured from the peroneal nerve. Data were analyzed in the time and frequency domains, and cross spectral analyses were performed to determine coherence relationships between mean CBV and MSNA, and between AP and MSNA. Low frequency (LF) oscillations were calculated in the 0.04– 0.15 Hz range, and high frequency (HF) oscillations were calculated in the 0.15–0.4 Hz range. Total oscillations (HF + LF) in AP [systolic (SAP), diastolic (DAP) and mean (MAP)], mean CBV and MSNA increased from baseline to pre-syncope (P B 0.08). There was a strong relationship between DAP and MSNA in both the HF and LF domains (R2 C 0.86), and a high average LF coherence of 0.74 across LBNP levels. While there was a weak association between HF oscillations in mean CBV and MSNA (R2 = 0.32), there was a good association between LF oscillations in mean CBV and MSNA (R2 = 0.73), also reflected in an average LF coherence of 0.62 across LBNP levels. Oscillations in AP and CBV showed the strongest association with MSNA oscillations in the LF range. These findings further support the relationship between LF oscillations in AP and MSNA and indicate that CBV LF oscillations may also be modulated by the sympathetic nervous system.

The effects of sex and aging on cerebral blood flow regulation B.M. Deegan1,2, F.A. Sorond3,4, L.A. Lipsitz5,6, G. O’Laighin1,2, J.M. Serrador1,2,4,6,7 1 Department of Electrical and Electronic Engineering, National University of Ireland, Galway, Galway, Ireland; 2 Biomedical Electronics Research Cluster, National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Galway, Ireland; 3 Brigham and Womens Hospital, Boston, MA, USA; 4 Harvard Medical School, Boston, MA, USA; 5 Institute for Aging Research, Boston, MA, USA; 6 Beth Israel Deaconess Medical Center, Boston, MA, USA; 7 Department of Neurology, Harvard Medical School, Boston, MA, USA

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288 Cerebral autoregulation is an intrinsic mechanism of the cerebrovasculature that maintains cerebral blood flow relatively constant over a wide range of blood pressures. Recent studies have shown sex differences in cerebral autoregulation in adolescents and young adults. Females have also been shown to have higher cerebral blood flow velocities than males. We evaluated cerebral autoregulation in 419 (186 male) subjects over the age of 63 recruited as part of the MOBILIZE Boston study. Beat by beat blood pressure was measured by photoplethysmography (Finometer), and cerebral blood flow velocity was measured using transcranial Doppler sonography. CO2 reactivity, transfer function gain and autoregulatory index (ARI) during sit to stand tests were assessed. The results showed that female subjects had significantly higher CO2 reactivity (P \ 0.001) and vasomotor range (P \ 0.001). Females also had higher cerebral blood flow velocities (male: 40.12 ± 0.85 cm/s, female: 43.06 ± 0.56 cm/ s, P = 0.001). However, linear regression analysis showed that females had a significantly greater rate of decrease in cerebral blood flow velocity with age than male subjects (male: -2.7 cm s-1 /decade, R2 = 0.02, female: -6.7 cm s-1 /decade, R2 = 0.13, P = 0.001). This greater rate of decrease with age in females was not due to impaired cerebral autoregulation, as females had higher ARI indices (P \ 0.001) and lower transfer function gain in the autoregulatory band (P \ 0.001), implying better cerebral autoregulation. Also, there was no age associated decrease in cerebral autoregulation in female subjects. Thus, the mechanisms of sex based differences in cerebral autoregulation, as well as the age related decline in cerebral blood flow velocity remain unclear, but the results of this study highlight the need for future work to better understand these underlying autoregulatory differences.

Acute effect of sildenafil (Viagra) on cerebrovascular hemodynamic responses in healthy males S. Jahshan, M. Zaaroor, V. Shik, M. Masoud, Y. Vardi, G. Jacob Recanati Autonomic Dysfunction Center, and Neurosurgery Department, Rambam Medical Center, Faculty of Medicine, Technion-IIT, Haifa, Israel Background: Headache remains the most common adverse effect of sildenafil; a selective phosphodiesterase 5 inhibitor (PDE5I). Yet, the precise mechanism behind this unpleasant side effect is still unknown. In this setting, we hypothesized that sildenafil affects cerebral blood flow by disrupting the cerebrovascular autoregulation mechanisms (CVAR). Methods: Fourteen young healthy males, mean age 34 ± 2 years old, were enrolled in the study. Beat-to-beat blood pressure (BP) and ECG, cerebral blood flow velocity (CBFv) measured with transcranial doppler (TCD), and end tidal CO2 (EtCO2), were assessed at baseline (EtCO2 * 39 mmHg), during hyperventilation (EtCO2 * 24 mmHg) and hypercapnia (EtCO2 * 48 mmHg), and during graded tilt and at graded doses of I.V. phenylephrine (25–200 lg). The study was repeated after the assumption of oral sildenafil 100 mg. Cerebral CO2-vasoreactivity was extrapolated from the changes in mean CBFv-related CO2. Both pressure dependent CVAR mechanisms, static and dynamic, were assessed by plotting the changes in BP against the changes in CBFv during the graded head up tilt and the boluses of phenylephrine, respectively. Results: Rest supine BP, HR, peak and mean CBFv, respiratory rate and EtCO2 were 117 ± 2/67 ± 3 mmHg, 69 ± 3 bpm, 84 ± 6 and 57 ± 4 cm/s, 16 ± 0.5 resp/min and 39 ± 0.9 mmHg, respectively. These parameters were not affected by sildenafil except for an increase in HR by 4.5 ± 2 bpm (P = 0.03). Sildenafil causes a significant increase in the CO2-vasoreactivity index, from 1.62 ± 0.1 to 1.83 ± 0.15 cm/s*mmHg (P = 0.04). However, acute PDE5 inhibition did not cause any change in the cerebrovascular hemodynamic in response to tilt and graded doses of phenylephrine.

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Clin Auton Res (2009) 19:275–316 Conclusion: Sildenafil enhances the cerebrovascular CO2-reactivity without affecting the pressure dependent autoregulatory mechanisms. This effect is probably mediated by the interference of the PDE5I in the nitric oxide pathway.

Plasma catecholamine profile in autoimmune autonomic ganglionopathy W. Singer, S. Vernino, P. Sandroni, P.A. Low Department of Neurology, Mayo Clinic, Rochester, MN, USA Objective: To assess the plasma catecholamine profile in a large cohort of well-characterized patients with autoimmune autonomic ganglionopathy (AAG). Background: AAG typically presents with subacute onset of severe generalized autonomic failure. Ganglionic acetylcholine receptor (AChR) antibodies can be found in some of these patients. However, many patients with clinically similar presentation are seronegative and atypical presentations exist. Based on a small case series, it was recently suggested that dihydroxyphenylglycol (DHPG) is relatively normal in AAG in contrast to low norepinephrine (NE) which would suggest abnormal ganglionic neurotransmission without significant postganglionic sympathetic denervation. Further characterization of the serum catecholamine profile in AAG may therefore not only be diagnostically helpful but may also advance our understanding of the pathophysiology of AAG. Methods: We assessed supine and standing catecholamines in 26 patients with AAG (14 antibody-positive), 17 patients with PAF, and 54 controls. DHPG was assessed in a subset of patients. All subjects underwent standardized autonomic reflex testing including QSART and cardiovascular responses to deep breathing, Valsalva maneuver, and head-up tilt. Autonomic dysfunction was quantified using the composite autonomic severity scale (CASS). Patients also underwent thermoregulatory sweat testing (TST) and sweat loss was quantified as percent body anhidrosis. Results: Plasma catecholamines, CASS, and sweat loss on TST were not different between antibody-positive and antibody-negative patients with AAG, but the latter group was younger. NE was significantly reduced in AAG compared to controls in the supine (120 ± 20 vs. 229 ± 15 pg/ml, P \ 0.001) and upright position (194 ± 38 vs. 447 ± 23 pg/ml, P \ 0.001), not different from patients with PAF. DHPG was similarly reduced in AAG in supine (651 ± 98 vs. 1,316 ± 50 pg/ml, P \ 0.001) and upright position (668 ± 109 vs. 1,441 ± 54 pg/ml, P \ 0.001). Conclusions: AAG is associated not only with significantly reduced NE but also with a significant reduction in DHPG, both to about 50% of normal. As DHPG mainly reflects NE turnover due to net leakage from storage vesicles, these data suggest in contrast to prior reports that AAG is associated not only with impairment of ganglionic neurotransmission, but also with significant postganglionic sympathetic denervation. This would be consistent with the common finding of marked postganglionic sympathetic sudomotor dysfunction and with the clinical observation that recovery of deficits is incomplete in the majority of patients with AAG. [Supported by NIH (P01 NS32352), Mayo GCRC (M01 RR00585), and Mayo Funds].

Modern approaches to diagnosis of diabetic cardiovascular autonomic neuropathy O.V. Mamontov, E.A. Shapkova, E.I. Krasilnikova, E.V. Shlyakhto Federal Centre of Heart, Blood and Endocrinology, Saint-Petersburg, Russian Federation

Clin Auton Res (2009) 19:275–316 Diabetic cardiovascular autonomic neuropathy (DAN) is an associated negative outcome in diabetes mellitus (DM). Clinical signs of autonomic dysfunction appear in late stages when DAN appears to be irreversible. Testing of the autonomic nervous system (ANS) helps to reveal patients with early changes. Objective: to test the diagnostic value of different markers of autonomic dysfunction in DM type 1 in order to optimize the diagnostic algorithm of early DAN. Patients and the methods: 60 patients (mean age 40.03 ± 13.33 years) with DM type 1 were examined. The DM duration was 18.8 ± 11.3 years. Control group consisted of 40 age and sex matched healthy subjects. The noninvasive beat-to-beat blood pressure monitor Finometer (FMS-Amsterdam) was used for blood pressure (BP) measurement as well as occlusion plethysmography (Dohn). Power spectral analysis of heart rate variability (HRV) and BP variability at rest and during tilt-test was performed, arterial baroreflex calculated. Other tests included Valsalva maneuver, test with the deep respiration, handgrip and cold-pressor tests, assessment index 30/15, and cardiopulmonary baroreflexes (CPBR) with low-body negative pressure -10 mmHg. Results: DAN was diagnosed in 38 (63%) DM patients according to one or more test positive. Factor analysis (principal components method) showed that the most significant independent components of autonomic dysfunction were: ‘‘chronotropic’’ factor, ‘‘vasomotor’’ factor and the factor of ‘‘tolerance to orthostasis’’, named so according to the physiological sense, which described 59% of total variance. ‘‘Vasomotor’’ factor was formed by variance of cold vasoconstriction, vasomotor component of CPBR and increase in diastolic BP during hand-grip test, whereas the factor of ‘‘tolerance to orthostasis’’ was formed by the value of a maximum decrease in systolic BP during tilt-test and by index 30/15. Remaining indices formed ‘‘chronotropic’’ factor. Most diagnostically significant (half-sum of positive and negative diagnostic value) were spontaneous baroreflex sensitivity for ‘‘the chronotropic’’, cold-pressor test for ‘‘vasomotor’’ factor and maximum decrease of systolic BP within the orthostatic period for the factor of ‘‘tolerance to orthostasis’’. By the way, there were no patients that had a diagnostically significant decrease of systolic BP during tilt-test without other signs of DAN. In other words, the orthostatic intolerance could be observed only in patients with combined DAN. Conclusion: Thus, in DM type 1 independent disturbances of chronotropic and vasomotor function of autonomic nervous system can be observed. At the same time, orthostatic intolerance is observed only in patients with the combined DAN profile. For DAN identification better diagnostic value has simultaneous arterial baroreflex estimation and cold-pressor test, and in the case of the combined failure tilt-test should be performed to exclude orthostatic intolerance.

The upregulation of catecholaminergic fibers in diabetes C. Gibbons, N. Wang, B. Illigens, C. Brown, R. Freeman Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA Background: The sympathetic innervation of sweat glands shifts from catecholaminergic to cholinergic in early development, but catecholaminergic innervation appears necessary for secretory responsiveness. Diabetic neuropathy results in sudomotor degeneration and regeneration but sweat output is often maintained or increased in early diabetic neuropathy. The corresponding structural sudomotor phenotypic changes that occur with neuropathy are not known. Objective: To quantify phenotypic changes to sudomotor fibers in early diabetic neuropathy.

289 Methods: Eight diabetic subjects and 10 healthy controls were studied by physical examination, sudomotor function testing, autonomic questionnaires and punch skin biopsies obtained at the distal leg, distal thigh and proximal thigh. Biopsies were stained with the panaxonal marker PGP 9.5, the cholinergic marker vasoactive intestinal peptide (VIP) and the catecholaminergic marker tyrosine hydroxylase (TH). The density of catecholaminergic and cholinergic fibers in sweat glands was determined in all subjects. Results: In sweat glands of healthy control subjects cholinergic expression (VIP) was greater than catecholaminergic expression (TH) (P \ 0.01 distal leg, P \ 0.01 distal thigh, P \ 0.01 proximal thigh). In diabetic subjects, the density of TH-positive fibers increased at the distal leg (P \ 0.0001), the distal thigh (P \ 0.001) and the proximal thigh (P \ 0.05) compared to healthy control subjects. The catecholaminergic up-regulation was seen in subjects without other evidence of neuropathy, including normal intra-epidermal nerve fiber densities, normal sudomotor nerve fiber density and normal physical examination. Conclusions: In subjects with diabetes there is a shift in expression from cholinergic to catecholaminergic fiber phenotypes around sweat glands in very early neuropathy. This finding may represent sudomotor nerve fiber regeneration and provide a means to maintain functional sweat output. Denervated sweat glands, analogous to observations during early development, may require catecholaminergic stimulation to return to functional status.

Peripheral nerve function in patients with clinical evidence of diabetic neuropathy C. Gibbons1, R. Freeman1, A. Veves2 1 Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2 Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA Background: Neuropathy is a debilitating complication of diabetes. Neurophysiologic techniques available to assess neuropathy include nerve conduction studies, autonomic testing, cutaneous blood flowmetry and quantitative sensory testing. These techniques evaluate different nerve fiber populations but there are few studies assessing the relationships among them. Objective: To quantify the neurophysiologic abnormalities in early diabetic neuropathy at the baseline visit of a prospective longitudinal study. Methods: Ninety-five subjects with diabetes and 27 healthy controls had detailed physical examinations, anthropomorphic measurements, autonomic testing (tilt table test, Valsalva maneuver, paced breathing), quantitative sensory testing [(QST) with thermal detection, thermal pain detection and vibration detection in hands and feet], nerve conduction studies [(NCS)- of the sural and peroneal nerves] and laser-Doppler blood flowmetry (of the foot and arm) monitored every 18 months for 3 years. Results: There were strong correlations between tests of small fiber sensory function (QST thermal and thermal-pain and axon-reflex blood flowmetry: R values of 0.47–0.79) between tests of autonomic function (Valsalva ratio, heart rate variability, tilt table testing: R values of 0.45–0.89) and between tests of large fiber function (NCS and QST vibratory perception: R values of 0.34–0.65). However, correlations among the testing modalities assessing different fiber populations were much lower with R values of 0.03–0.62. Conclusions: Significant inter-test heterogeneity is seen suggesting nerve dysfunction varies across different fiber subtypes. In individual patients, no single test adequately assesses neuropathy sub-type or neuropathy severity. Combinations of tests that measure autonomic,

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290 small and large sensory fiber function are necessary to adequately quantify all the features of a diabetic peripheral neuropathy.

The effects of hypoglycemic and euglycemic hyperinsulinemia on aldosterone G.K. Adler1, I. Bonyhay2, V. Curren1, E. Waring2, R. Freeman2 1 Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA; 2 Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA Background: Strict glycemic control increases the incidence of hypoglycemia and is associated with increased mortality in type 1 and 2 diabetes and critically ill patients. We previously showed that baroreflex sensitivity, a predictor of mortality, is attenuated in healthy subjects more than 12 h after hypoglycemia. The mechanism whereby baroreflex function is attenuated after antecedent hypoglycemia is not known. Acute infusions of aldosterone attenuate baroreflex sensitivity while angiotensin type 1 receptor antagonism and angiotensin converting enzyme inhibition restores attenuated baroreceptor sensitivity. We therefore sought to define the effects of hypoglycemia on aldosterone. Methods: Aldosterone and its two major secretagogues plasma renin activity (PRA) and adrenocorticotropic hormone (ACTH) were assessed. In study 1, 13 healthy individuals (27 ± 2 years; 5 males) on a controlled normal sodium diet participated in euglycemic (5.0 mmol/l) hyperinsulinemic and hypoglycemic (2.8 mmol/l) hyperinsulinemic clamp protocols, separated in time by 4 weeks. In study 2, 13 healthy women (40 ± 2 years) on a controlled low sodium diet participated in a stepped hypoglycemic hyperinsulinemic clamp protocol; blood glucose was decreased from 5.0 to 2.2 mmol/l by 0.55 mmol/l every 30 min. Results: In Study 1, aldosterone levels increased approximately 2.5fold during hypoglycemia, P \ 0.001, but did not rise with euglycemia. PRA increased during both hyperinsulinemic clamps; however, the increase was greater during hypoglycemia [D = 1.5 ± 0.2 ng/(ml h)] as compared with euglycemia [D = 0.5 ± 0.1 ng/(ml h)], P \ 0.005. In study 2, glucose levels of 2.8 mmol/l and below stimulated significant increases in aldosterone, from 417 ± 57 pmol/l at baseline to 1,314 ± 69 pmol/l at the end of the study (P \ 0.0001). Increases in aldosterone paralleled those of ACTH. Conclusion: Hypoglycemia increases aldosterone and its secretagogues PRA and ACTH. Because aldosterone activation of the mineralocorticoid receptor plays a critical role in the pathophysiology of cardiovascular and renovascular injury including inflammation and cardiac arrhythmias, these findings may be of relevance in individuals who experience episodes of hypoglycemia.

Poster Session I Poster #1 Change in thoracic fluid content has a linear relationship with change in heart rate in patients with POTS S. Ashfaq, R. Horne, M. Ishaque, P. Reddy, T. Fugitt, A. Suleman The Heartbeat Clinic, Dallas, TX, USA

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Clin Auton Res (2009) 19:275–316 Postural tachycardia syndrome (POTS) is characterized by excessive tachycardia without hypotension during orthostasis. Impedance cardiography (ICG), which assesses cardiac function by measuring the opposition to an alternating electric current in the thorax, indicates the amount of fluid in the thorax. The thoracic fluid content (TFC) indicates preload. Current data suggests an inverse relationship between heart rate and stroke volume during upright tilt. ICG has been used to assess hemodynamic parameters during tilt table test. The current study was undertaken to assess if change in TFC carries any relationship with change (D) in heart rate during tilt in patients with POTS. 23 patients with POTS were evaluated during 30 min head up tilt at 80
. An increase in heart rate (HR) more than 30 was used as a diagnosis of POTS. Coefficient of correlation was calculated for change in stroke volume (D SV) (DSV = SV supine minus SV after 30 min tilt) and change in thoracic fluid content (DTFC) (DTFC = TFC supine minus TFC tilt) This data was plotted against change in heart rate DHR (DHR = HR tilt minus HR supine). Results showed SV baseline 70 ± 16, tilt 41 ± 10, DSV 19.9 ± 14, cardiac output (CO) baseline 4.96 ± 0.9, tilt 4.3 ± 1.1, TFC Baseline 27 ± 4.3, Supine 25.2 ± 3.8 DTFC 2.0 ± 3.3 HR baseline 71 ± 16, HR tilt 11.75 ± 17.9, DHR42 ± 10. DTFC was very strong predictor of DHR (R2 0.88) while DSV failed to show a linear relationship with DHR or DTFC. Our study proposes (1) during tilt table test using ICG, TFC should be reported. (2) DTFC is a much stronger predictor of DHR then DSV. (3) Lack of a strong relationship between DTFC and DSV may mean that patients with POTS have other mechanisms beside venous return that determine SV and these patient may be operating at a different slope of Frank Starling curve.

Poster #2 Heart rate recovery characteristics in the postural tachycardia syndrome: factors influencing a return to baseline K.A. Mayuga, C. Gaw, C. Tatsuoka, F. Fouad-Tarazi Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH, USA Aim: Postural tachycardia syndrome (POTS), a heart rate (HR) rise with upright positioning, is dependent on autonomic influences. HR recovery, a HR decrease to baseline levels after exercise cessation, is another measure of autonomic activity with prognostic significance. HR recovery characteristics in patients with POTS have not been elucidated. Methods: Data from 114-subjects diagnosed with POTS during headup tilt table testing were analyzed. HR’s were recorded during supine position pre-tilt (baseline), 70-degree tilt, and at 10-s intervals up to 3min after a return to supine. 10-s ‘complete’ HR recovery (c-HRR) was defined as a HR-decrease to within 10% of baseline HR-levels within 10-s after a return to supine. Age, gender, time during 70degree tilt until the diagnosis of POTS (time-to-POTS), and baseline HR were analyzed. P \ 0.05 was significant. Results: c-HRR was achieved in 36 subjects. Gender did not influence c-HRR (P = 0.26). Younger age was associated with c-HRR (36 ± 13 years old with c-HRR vs. 44.1 ± 17.6 years old without cHRR, P = 0.0027). Faster pre-tilt HR was associated with c-HRR (71.8 ± 13.6 bpm with c-HRR vs. 67 ± 13.2 bpm without c-HRR, P = 0.025). A longer Time-to-POTS was associated with c-HRR (18.7 ± 12.1 min time-to-POTS with c-HRR vs. 15.2 ± 12.6 min time-to-POTS without c-HRR, P = 0.022). No interactions were found.

Clin Auton Res (2009) 19:275–316

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Conclusion: Faster HR recovery was seen with younger age, faster pre-tilt heart rates, and longer time-to-POTS. Further study is needed regarding symptoms, prognosis, and possible mechanisms.

rise in POTS. Vagal responses are marked reduced to orthostatism in POTS patients and sympathetic indexes have an abrupt rise compared with normal controls. Neurohormonal and autonomic differences to passive head-up tilt could explain partly the symptoms of POTS patients.

Poster #3 Poster #4 Neurohormonal and autonomic changes after head-up tilt in postural tachycardia syndrome (POTS) J. Freitas1,3, R. Santos1, F. Boomsma2, M.J. Maciel1, F. Rocha-Goncalves3 1 Centro Estudos Funcao Autonomica, Hospital de Sao Joao, Portugal; 2 Erasmus University and Dijkzit Hospital, Rotterdam, The Netherlands; 3 Faculdade de Medicina do Porto, Portugal Neurohormonal and autonomic responses to acute orthostatic stress are not clear in patients with postural tachycardia syndrome. The goal of this study was the assessment of neurohormonal and autonomic changes to passive tilting that could characterize patients with postural tachycardia syndrome. We studied 12 normotensive control subjects and 8 patients with postural tachycardia syndrome (POTS), aged-matched. Blood was sampled at supine rest (S) and passive orthostatic stress (T). We measured atrial and brain neuropeptides (ANP and BNP) and catecholamines (NOR, EPI and DOP). We also calculated the heart rate variability, systolic blood pressure variability and baroreceptor gain with FFT spectral analysis.

Controls-S Controls-T POTS-S ANP (pmol/L) BNP (pmol/L) NOR (pg/ml) EPI (pg/ml) DOP (pg/ml) BRG (mmHg/ms)

7±4

7±5

3±1

POTS 3±2

2±2 2±1 1±1 1±1 166 ± 083 363 ± 201 135 ± 037 475 ± 129 14 ± 11

32 ± 24

22 ± 17

49 ± 30 10 ± 7

7±4

8±2

6±2

15 ± 7

8±3

16 ± 7

3±2

HF_RR (ms2)

550 ± 376 196 ± 112 657 ± 539

30 ± 21 5.3 ± 2.2

LF/HF

1.2 ± 0.8

3.5 ± 2.8

1.6 ± 1.4

LF_SBP (mmHg2)

3.4 ± 1.9

9.1 ± 7.3

3.3 ± 2.5 15.0 ± 3.5

HR (bpm)

75 ± 8

88 ± 7

80 ± 11

122 ± 8

Natriuretic peptides do not change after orthostatic stress in any group but are lower in POTS, probably due to the significant hypovolemia observed in these patients. Norepinephrine showed a huge

Cardiovascular and sympathetic neural responses to handgrip and cold pressor stimuli in the postural orthostatic tachycardia syndrome Q. Fu1,2, T.B. VanGundy1, S. Shibata1,2, M.M. Galbreath1,2, B.D. Levine1,2 1 Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; 2 The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA Background: Patients with the Postural Orthostatic Tachycardia Syndrome (POTS) often have exercise intolerance, and the underlying mechanisms remain unclear. We tested the hypothesis that the exercise pressor response would be impaired in these patients. Method: Twenty-eight POTS patients (27 females, 1 male) and 16 healthy controls (15 females, 1 male) matched for age and body mass index were studied. Heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded continuously before and during static handgrip sustained to fatigue at 40% of maximum voluntary contraction, followed by 2 min of circulatory arrest. A cold pressor test was also performed to determine the integrity of central vasomotor processes and their efferent pathways. Results: Baseline HR was greater in patients than controls, while baseline BP and MSNA were similar between groups. At the same relative fatiguing force, the peak systolic and diastolic BP during static handgrip did not differ between groups. Even though absolute values of HR were consistently greater in patients than controls, the contractioninduced rises in HR were not different between groups (P = 0.561 for interaction). Contraction-evoked peak MSNA responses were similar between patients and controls [30.4 ± 2.3 (SE) vs. 29.9 ± 3.1 bursts/ min, P = 0.873; 32.5 ± 2.4 vs. 36.8 ± 3.8 bursts/100 heart beats, P = 0.287]. MSNA during post-handgrip circulatory arrest was also similar between groups (23.4 ± 2.1 in patients vs. 22.4 ± 2.5 bursts/ min in controls, P = 0.760; 31.2 ± 3.2 vs. 34.1 ± 3.9 bursts/100 heart beats, P = 0.483). Responses of MSNA and BP to the cold pressor test did not differ between POTS patients and healthy controls, even though HR was greater in patients. Conclusions: These results suggest that the muscle metaboreflex, mechanoreflex, and central command were all intact in POTS patients. Thus, other factors (i.e., reduced stroke volume during exercise), rather than the impaired pressor response contribute to exercise intolerance in these patients. Supported by NIH K23 (HL0752 83) and GCRC grant (RR00633).

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Poster #5 Chronic treatment with propranolol does not alter sympathetic neural responses to handgrip and cold pressor stimuli in the postural orthostatic tachycardia syndrome Q. Fu1,2, T.B. VanGundy1, S. Shibata1,2, M.M. Galbreath1,2, B.D. Levine1,2 1 Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX, USA; 2 The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA Background: Non-selective beta-adrenergic blockade is commonly used in patients with the Postural Orthostatic Tachycardia Syndrome (POTS). Whether such drugs can alter the exercise pressor reflex in these patients is unknown. We tested the hypothesis that sympathetic neural responses to static handgrip and cold pressor stimuli would be attenuated after chronic treatment with propranolol in POTS patients. Methods: Seventeen POTS patients (16 females and 1 male, age range 15–44) were studied before and after 4 weeks of either propranolol (oral 80 mg qd, n = 8) or placebo (n = 9) treatment. Heart rate (HR), blood pressure (BP) and muscle sympathetic nerve activity (MSNA) were recorded continuously before and during static handgrip sustained to fatigue at 40% of maximum voluntary contraction, followed by 2 min of circulatory arrest. A cold pressor test was also performed to determine the integrity of central vasomotor processes and their efferent pathways. Results: Baseline HR was lowered significantly by propranolol, but baseline BP and MSNA remained unchanged. At the same relative fatiguing force, the peak systolic and diastolic BP during static handgrip was not affected by propranolol (P = 0.179 and 0.127 for treatment). Even though absolute values of HR were consistently lower after propranolol treatment, the contraction-induced rises in HR were not different from those before treatment (P = 0.373 for interaction). Contraction-evoked peak MSNA burst frequency was reduced by propranolol [33 ± 15 (SD) pre- vs. 25 ± 7 bursts/min post-treatment, P = 0.042], but peak MSNA burst incidence (36 ± 17 vs. 36 ± 13 bursts/100 heart beats, P = 0.932) and total activity (677 ± 162 vs. 634 ± 221 units/min, P = 0.484) remained unchanged. MSNA during post-exercise circulatory arrest was not affected by propranolol treatment. Responses of MSNA and BP to the cold pressor test did not differ before and after treatment, even though HR was lowered markedly by propranolol (P \ 0.001 for treatment). Placebo had no impacts on BP, HR and MSNA responses during both static handgrip and the cold pressor test. Conclusions: These results suggest that chronic treatment with nonselective beta-blocker propranolol did not alter the muscle metaboreflex, mechanoreflex and central command in patients with POTS. Thus, patients’ exercise capacity and physical function seem to be preserved with propranolol treatment. Supported by NIH K23 (HL0752 83) and GCRC grant (RR00633).

Poster #6 Chemoreceptor sensitivity in postural tachycardia syndrome I. Taneja, M.S. Medow, A.J. Ocon, D.A. Clarke, J.M. Stewart Department of Pediatrics, New York Medical College, Valhalla, NY, USA

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Clin Auton Res (2009) 19:275–316 Chemoreceptor sensitivity was measured in 18 postural tachycardia syndrome (POTS) (14 females and 4 males) and 12 healthy control subjects (8 females and 4 males) 16–35 year old by exposing them to eucapneic hyperoxia (30% oxygen), eucapneic hypoxia (10% oxygen) and hypercapnia (30% oxygen + 5% carbon dioxide). Each subject inhaled all gases in randomized order in supine position for 5 min each with adequate rest in between the conditions. Heart rate (HR), mean arterial pressure (MAP) oxygen saturation and end tidal carbon dioxide (ETCO2) were measured. Chemoreflex sensitivity was ascertained by comparing slopes determined from eucapneic hypoxiahyperoxia to measure peripheral chemoreflex sensitivity, and hyperoxic hypercapnia–eucapnia to measure central chemoreflex sensitivity. Results were compared by repeated measures ANOVA. POTS had significantly higher resting HR, peripheral resistance, lower cardiac output and stroke volume as compared to controls (P \ 0.05). Hypoxia and hypercapnia increased the HR, cardiac output, stroke volume and decreased peripheral resistance in all subjects (P \ 0.05). As compared to controls, POTS had attenuated increases in stroke volume (P \ 0.05) and minute ventilation during hypoxia (relative change in minute ventilation-POTS vs. controls, 1.7 ± 0.2 vs. 3.5 ± 1.1, P = 0.003) although minute ventilation was much greater in control males than control females (5.6 ± 1.2 vs. 2 ± 0.2, P \ 0.05). Following hypoxia POTS compared to controls had attenuated decreases in oxygen saturation (delta oxygen saturation—11.9 ± 1.7 vs. 15.3 ± 3.4, P = 0.003) because of decreased peripheral chemoreflex sensitivity. Subjects with lower resting blood pressures had lower decreases in their oxygen saturation than those with higher resting blood pressures (r2 = 0.479, P \ 0.011). POTS have attenuated chemoreflex sensitivity compared to healthy subjects.

Poster #7 Defects in cutaneous angiotensin converting enzyme 2 and angiotensin-(1–7) production in postural tachycardia syndrome J.M. Stewart, A.J. Ocon, D. Clarke, I. Taneja, M.S. Medow Departments of Pediatrics, Physiology and Medicine, New York Medical College, Hawthorne, NY, USA Postural tachycardia syndrome (POTS) is associated with increased plasma angiotensin-II (Ang-II). Ang-II administered in the presence of NOS inhibition with nitro-L-arginine (NLA) and AT1R blockade with losartan produces vasodilation during local heating in controls. We tested whether this ‘‘Ang-mediated vasodilation’’ occurs in POTS and whether it is related to angiotensin converting enzyme 2 (ACE2), and Ang-(1–7). We used local cutaneous heating to 42
C and laser Doppler flowmetry to assess NO-dependent conductance at four calf sites in 12 low flow POTS and in 12 control subjects aged 17.6– 25.5 years. We perfused Ringer’s solution through intradermal microdialysis catheters and performed local heating. We perfused one catheter with NLA (10 mM) + losartan (2 lg/L), repeated heating, and NLA + losartan + Ang-II (10 lM) repeating heating a third time. A second catheter received NLA + losartan + Ang-II, heated, perfused NLA + losartan + Ang-II + DX600 (1 mM, an ACE2 inhibitor), and reheated. A third catheter received NLA + losartan + Ang-II, heated, perfused NLA + losartan + AngII + angiotensin-(1–7) [100 lM, Ang-(1–7)], and reheated. The fourth catheter received Ang-(1–7) then reheated a second time only. Ang-mediated vasodilation was present in control but not POTS. Ang-mediated dilation was eliminated by DX600 indicating an ACE2-related effect. Ang-mediated vasodilation was restored in POTS by Ang-(1–7). When administered alone during locally

Clin Auton Res (2009) 19:275–316 mediated heating, Ang-(1–7) improved the NO-dependent local heating response. ACE2 effects are blunted in low flow POTS and restored by the ACE2 product angiotensin-(1–7). Data imply impaired catabolism of Ang-II through the ACE2 pathway. Vasoconstriction in POTS may result from a reduction in Ang-(1–7) and an increase in Ang-II.

Poster #8 Postural orthostatic tachycardia syndrome with ganglionic nAChR autoantibody positivity V. Iodice1, K. Kimpinski1, P. Sandroni1, S. Vernino2, P.A. Low1 1 Department of Neurology, Mayo Clinic, Rochester, MN, USA; 2 Department of Neurology, UT Southwestern Medical Center, Dallas, TX, USA Background: POTS is a chronic form of orthostatic intolerance characterized by inappropriate, excessive increase in heart rate (HR) without orthostatic hypotension (OH) during orthostatic stress. It was previously reported that 15% of patients with POTS had low levels of ganglionic a3 acetylcholine receptor (nAChR) antibody levels. Our objective was to determine whether clinical or autonomic parameters differ in POTS patients who are seropositive compared to those that are negative for the ganglionic nAChR antibody. Methods: We undertook a retrospective study of patients previously diagnosed with POTS who underwent autonomic function tests (autonomic reflex screen, TST, plasma catecholamine levels), determination of ganglionic nAChR antibody and 24-h urinary volume and sodium level. Descriptive statistics are presented as mean ± SD. Results: The dataset comprised 43 patients with POTS. They were predominantly female (83.7%) with a mean age of 31.4 ± 9.3 years. Seven patients were ganglionic nAChR antibody positive and 36 were antibody negative. Mean ganglionic nAChR antibody level was 0.10 ± 0.01 nmol. There were no significant differences between the two groups with regard to age, autonomic function tests, symptoms duration or disease duration. There was no significant correlation between CASS score, degree of anhidrosis, heart rate increase to head-up tilt and ganglionic nAChR antibody levels. Conclusions: No clinical characteristics or autonomic function tests differentiate antibody positive from antibody negative POTS cases. Patients with high levels of ganglionic nAChR antibody have a consistent relationship to CASS suggesting that the antibody causes autoimmune autonomic ganglionopathy (AAG). However low ganglionic nAChR antibody levels seen in a minority of patients with POTS have uncertain significance. The routine use of this test in the evaluation of POTS is unwarranted. We speculate that there is a wide spectrum of severity of AAG, and mild limited forms of AAG may meet criteria for POTS. However, this subset of AAG is too mild to show a relationship between low antibody levels and low CASS.

Poster #9 Gynecological abnormalities and catamenial lightheadedness in postural tachycardia syndrome D. Enayat, D. Robertson, B.K. Black, I. Biaggioni, N.R. Keller, S.R. Raj Vanderbilt University, Nashville, TN, USA

293 Background: Postural tachycardia syndrome (POTS; heart rate increase [30 bpm on standing) affects predominantly women of child-bearing age. Blood volume regulating hormones are known to vary during different phases of the menstrual cycle. In this study we assessed reproductive and gynecological histories, and menstrual cycle phased-based symptom variability in POTS compared to control subjects. Methods: Female patients with POTS [n = 65, 33 ± 3 (mean ± SEM) years] and healthy female control subjects (n = 92, 33 ± 3 years) completed a customized self-administered questionnaire assessing current reproductive status, menstrual cycle history and gynecological disorders. Non-dichotomous questions used Likert scales with anchors. Lightheadedness ratings were converted to a 100 point scale (higher is more faint). The questionnaires were originally administered on paper, but later administered using a secure webbased interface. Analyses were performed using Fisher’s exact test, Mann–Whitney U, and RM ANOVA. P \ 0.05 were considered statistically significant. Results: Compared with controls, POTS patients had significantly higher incidences of dysfunctional uterine bleeding (13.8 vs. 4.3%, P = 0.042), endometriosis (20.0 vs. 5.4%, P = 0.009), uterine fibroids (24.6 vs. 9.8%, P = 0.015), galactorrhea (9.2 vs. 0%, P = 0.004), ovarian cysts (43.1 vs. 13.0%, P \ 0.001), and hysterectomy in POTS (16.9 vs. 4.3%, P = 0.012). POTS patients experienced more lightheadedness in each phase of the menstrual cycle: premenstrual phases (60 ± 4 vs. 54 ± 3; P = 0.026), menstruation (74 ± 4 vs. 58 ± 2; P \ 0.001), early postmenstrual (53 ± 3 vs. 44 ± 3; P = 0.001), and late postmenstrual (46 ± 3 vs. 42 ± 3; P = 0.010). The catamenial variability of lightheadedness was statistically significant (P \ 0.001), but was not different between groups (PINT = 0.609). Conclusion: There is catamenial variability in lightheadedness reported in POTS, but this variability is not unique to POTS. Patients with POTS have a higher incidence of gynecological disorders and hysterectomies. Further investigation is needed to understand whether these gynecological abnormalities are causally related to POTS or are secondary to the POTS diagnosis.

Poster #10 The effect of pregnancy on postural tachycardia syndrome K. Kimpinski, V. Iodice, P. Sandroni, P.A. Low Department of Neurology, Mayo Clinic, Rochester, MN, USA Background: Postural tachycardia syndrome (POTS) is a disorder of orthostatic intolerance that predominantly affects women. Onset is between 18 and 50 years, including the prime child bearing years. Therefore, the relationship between POTS and pregnancy is a common question in clinical practice. However, there is no published data on the subject. The objectives of this study were: (1) to determine whether pregnancy alters the clinical course of POTS; (2) to describe the pregnancy outcomes in POTS patients. Methods: Women who had at least one pregnancy occurring in conjunction with postural tachycardia syndrome were studied using standard autonomic testing. All patients were evaluated at the Autonomic Disorders Center, Mayo Clinic (Rochester, MN). Women with at least one pregnancy during their diagnosis of POTS as confirmed by head up tilt (n = 50) were compared to a control group of nonparous women diagnosed with POTS (n = 61). Results obtained from standard autonomic testing were described using the Composite Autonomic Severity Scale (CASS) score.

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294 Results: There were no significant differences between women who had been pregnant and those who had not in respect to heart rate (HR) parameters (pregnant, HR supine: 77.4 ± 2.1, HR standing: 119.7 ± 2.4, D HR: 42.8 ± 1.2; non-pregnant HR supine: 79.2 ± 1.6, HR standing: 121.1 ± 2.1, D HR: 41.3 ± 1.4) and standard autonomic testing (pregnant CASS score: 2.0 ± 0.2; nonpregnant CASS score: 2.1 ± 0.1). Clinical symptoms did not differ between groups. Disease progression was considered stable or improved in 90% of the patients in the pregnancy group and 93% of the non-pregnant group. Complications in pregnancy occurred in 3 of the 50 pregnant women (6%). These included 2 spontaneous abortions (between weeks 6 and 25) and malpresentation with placental abruption. In the latter case, the infant after delivery was healthy. There was no clear association with POTS in any of these cases. There were no other significant maternal complications. Conclusions: Pregnancy does not appear to alter the clinical course of POTS. POTS does not compromise maternal or fetal health during pregnancy or delivery. Complications during pregnancy were in keeping with that expected from complication rates in the general public. Further prospective studies are planned.

Poster #11 Familial co-morbidities of interstitial cystitis E. Heller1, C.T. Buffington2, R. Rackley3, D. Zhang1, T. Chelimsky1 1 Neurology Institution, University Hospitals Case Medical Center, Cleveland, OH, USA; 2 Veterinary Medicine, Ohio State University, Columbus, OH, USA; 3 Urology Department, Cleveland Clinic Foundation, Cleveland, OH, USA Background: Patients with interstitial cystitis (IC) are known to harbor other autonomic disorders, such as functional dyspepsia, irritable bowel syndrome, fibromyalgia and migraine headaches. The purpose of this investigation is to determine what comorbidities, if any, are associated with family members of IC patients. Methods: Data were collected using the previously reported ODYSA questionnaire. The questionnaire includes a question set for each of 12 disorders using established inclusion criteria where available. The frequency of each disorder was analyzed in a group of 34 subjects who were first-degree family members of patients with a clinical diagnosis of interstitial cystitis. The 34 subjects included mothers (4), fathers (2), grandparents (3), full brothers (6), full sisters (8), uncles (2), aunts (1), daughters (7), and sons (1). Results: The average age of the subjects was 48 ± 23 with 22 females and 12 males. Only two family members (a daughter and a maternal grandfather) were found to have IC based on NIDDK criteria. The disorders with the highest incidences in family members of patients with IC were migraine headaches (26.5%), irritable bowel syndrome and fibromyalgia (17.7%) and orthostatic intolerance (14.7%). The average number of co-morbidities per family member is 1.15. Discussion: Based on previously reported data, patients with IC have an average of 3.7 autonomic disorders, with the most common being functional dyspepsia, irritable bowel syndrome and fibromyalgia. Family members of IC patients were only found to have an average of 1.15 autonomic disorders. Though they harbor far fewer comorbidities, family members and probands share the same associative disorders. This may play an important role in determining the order in which IC develops in the dysautonomia and how best to treat IC.

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Poster #12 Effects of sacral nerve stimulation on sympathetic nerve activity during graded head up tilt: a case report L. Diedrich1, P. Konrad2, A. Diedrich3, K. Sato3, D. Sukdeb3 1 Interventional Pain Center, Department of Anesthesiology; 2 Neurosurgical Sciences Department of Surgery; 3 Autonomic Dysfunction Center, Department of Clinical Pharmacology at Vanderbilt University, Nashville, TN, USA The pharmacological management of chronic visceral pain (CVP) is a challenging task. Neuromodulation of sacral nerves (NSN) has been introduced successfully to treat voiding dysfunction and visceral pain. The mechanism of action is unknown. An inhibitory effect on sympathetic outflow similar to spinal cord stimulation has been proposed. We tested the hypothesis that sacral nerve stimulation will alter the sympathetic response to orthostatic stress. This is a case report of a 41 year old female with a history of 3 years of chronic pelvic pain and chronic cystitis. A sacral nerve stimulator has been implanted with lead placement on the right third sacral foramen. Heart rate (HR), blood pressure (BP), muscles sympathetic nerve activity (MSNA), and catecholamine levels were measured during graded tilt (4 steps at 5 min, 15
increments) with stimulator turned ‘‘on’’ and ‘‘off’’ on two different days. Sacral stimulation caused a decrease of supine HR from 82 to 66 bpm, increase of systolic BP from 109 to 132 mmHg, increase of diastolic BP from 58 to 73 mmHg while pain level, MSNA activity, and NE were unchanged (7 vs. 7, 15 vs. 15 bursts/min, 304 vs. 296 pg/ml). During final 60
tilt episode, sacral stimulation decreased pain level from 10 to 8; decreased HR from 102 to 80 bpm; increased systolic BP from 130 to 142 mmHg; and diastolic BP from 72 to 84 mmHg decreased MSNA from 35 to 10 bursts/min and NE from 570 to 398 pg/ml. These results demonstrate that sacral nerve stimulation decreased significantly sympathetic nerve activity during orthostatic stress. The important impact of neuromodulation on autonomic function has to be studied in more patients in future.

Poster #13 Gender differences in autonomic reactivity to stress in IBS and healthy children M. Puzanovova1, A. Diedrich2, L.S. Walker1 1 Department of Pediatrics, Division of Adolescent Medicine and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; 2 Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA Aims: We investigated gender differences in heart rate variability (HRV) and blood pressure (BP) reactivity to psychological and thermal stressor in pediatric patients with irritable bowel syndrome (IBS) and well children. Materials and methods: Subjects were 20 IBS patients (10 boys;10 girls) age and gender matched with 20 healthy children 10–17 years of age (M = 14.2). Heart rate was continuously recorded on a dual-lead ECG system (Biopac Inc.). HRV parameters were calculated directly from electrode tracings after customized peak detection (HRVAnalyzer, Diedrich). Data were analyzed using FFT and wavelet techniques. Blood pressure (systolic, diastolic and MAP) was recorded

Clin Auton Res (2009) 19:275–316 on Dinamap every 2 min throughout the study. BMI and Tanner stage was recorded in every subject. Overall HRV and the following epochs were evaluated: initial 5 min. baseline; 2 min. Serial Subtraction Test (SST); 5 min. recovery; thermal stimulation of the forearm and measurement of pain threshold and pain tolerance and final 5 min. recovery period. Frequency domains evaluated were: total power (TP); high frequency (HF) 0.15–0.4 Hz and low frequency (LF) 0.04– 0.15 Hz. We used 2 sample t-test for parametric and Kruskal–Wallis for non-parametric continuous outcome measures, and a mixed effects model to evaluate group differences over time. Results and Conclusion: Overall, increased HRV in the LF, HF and TP range was noted in healthy subjects (all P \ 0.01). The two major findings in this study are: significantly higher HRV in healthy boys compared to IBS boys (P \ 0.05) with pronounced difference in the HF range (P \ 0.001), and significantly higher HRV in the HF range in healthy boys compared to healthy girls (P = 0.002). IBS boys reacted similarly to healthy boys only during SST, otherwise they resembled IBS girls in response to thermal pain stimulus. Gender differences have to be taken into an account when evaluating HRV in older children.

Poster #14 Migraines and gastroparesis: a clinical and treatment outcome analysis M. Isani, C. Lahr, J. Hughes, L. Halley, A. Kedar, T. Kothari, C. Subramony, T. Abell, R. Schmeig Flowood, MS, USA Purpose: This study was performed to identify any clinical or treatment differences between patients with migraine and those without migraines undergoing permanent gastric electrostimulation. Methods: We reviewed data on 80 patients (28 migraine and 52 no migraine) undergoing permanent gastric electrical stimulation. Symptoms evaluated included nausea, vomiting, epigastric pain, bloating, and early satiety. Each symptom was scored from 0 to 4 based upon frequency and severity: 0-absent, 1-not limiting activities and less than once a week, 4-limiting patient to bedrest and more than 7 times per week. Total symptom score (TSS) is the sum of the individual scores of nausea, vomiting, epigastric pain, bloating, and early satiety. Vomiting score and TSS were measured before treatment and during treatment with temporary gastric electrical stimulation. Four hour gastric emptying time (GET) was measured before and during treatment. Outcomes were measured as change in vomiting scores, change in TSS, and change in 4 h GET. Results: Two tailed unpaired t tests were performed for each clinical and treatment outcome. The following means and P values were listed for each parameter with the migraine mean listed, followed by the non migraine mean, followed by the P value difference: baseline 4 h GET scan, 0.13, 0.25, 0.02; treatment 4 h GET scan 0.16, 0.26, 0.08; 4 h GET scan change 0.02, 0.01, 0.89; baseline vomiting 2.91, 1.87, 0.00; treatment vomiting 0.34, 0.43, 0.71; vomiting change -2.50, -1.34, 0.00; Baseline TSS 15.61, 13.68, 0.03; treatment TSS 5.48, 4.41, 0.34; and TSS change -10.44, -9.12, 0.27. Conclusion: Those patients with gastroparesis undergoing permanent gastric electrical stimulation who had migraine headaches had significantly higher incidence of vomiting at baseline and worse total symptoms at baseline. Yet, they had significantly better gastric emptying at baseline. The patients with migraine headaches had significantly more improvement in vomiting scores. However, overall change in TSS was not significantly different between patients with migraine and those without migraines. Therefore, patients with migraines have equal likelihood of improvement after gastric electrical stimulation.

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Poster #15 Migraines and gastroparesis: a histophysiologic analysis M. Isani, C. Lahr, J. Hughes, L. Halley, A. Kedar, T. Kothari, C. Subramony, T. Abell, R. Schmeig Flowood, MS, USA Purpose: This study was performed to identify any histologic and electrophysiologic differences between patients with migraines and those without migraines with gastroparesis that are undergoing permanent gastric electrostimulation. Methods: We reviewed data on 80 patients (28 migraine and 52 no migraine) undergoing permanent gastric electrical stimulation for gastroparesis. Evaluation included frequency and amplitude of cutaneous EGG, mucosal EGG and serosal EGG. The pathologist counted and averaged the number of CD117 (Cajal cells) and S100 (neuronal cells) per hpf from10 high powered fields from full thickness gastric biopsies. Results: Two tailed unpaired t tests were performed for each parameter: The following means and P values were listed for each parameter with the migraine mean listed, followed by the non migraine mean, followed by the p-value difference: Outer S-100, 7.40, 9.30, 0.58; Inner S-100, 11.10, 15.0, 0.35; Outer CD-117, 10.20, 8.60, 0.49; Inner CD-117, 12.30, 11.30, 0.61; Cut EGG Freq, 4.90, 5.50, 0.17; Cut EGG AMP, 0.11, 0.14, 0.41; Muc EGG Freq, 5.40, 5.10, 0.64; Muc EGG AMP, 1.12, 0.74, 0.05, Ser EGG Freq. 5.40, 5.70, 0.40; and Ser EGG AMP 0.52, 0.55, and 0.84. Conclusion: Histologic and electrophysiologic evaluations of those patients with migraines and those without migraines with gastroparesis only show a statistically significant difference in mucosal amplitude. Migraines do not contraindicate gastric stimulation.

Poster #16 Evaluation of symptoms and psychosocial issues in younger patients with neurogenic orthostatic hypotension J.L. Gilden, D. Vahedi, A. Nuygen, A. Garg, N. Patel, R. Marri, S. Ubhayakar Diabetes/Endocrinology Division, Rosalind Franklin University of Medicine and Science/Chicago Medical School, North Chicago, Saints Mary and Elizabeth Medical Center, Chicago, IL, USA Background: Autonomic neuropathy (AN) can result in abnormal regulation of the cardiovascular system, producing orthostatic hypotension (NOH). Other features of AN may include: abnormal gastrointestinal function, disorders of the bladder, sexual dysfunction, inappropriate sweating, pupillary reflex abnormalities, venous pooling, and sleep apnea. Many patients with symptomatic NOH also describe extreme fatigue, tiredness, and depressed moods, as well as decreased quality of life. Methods: We evaluated 56 patients with NOH for other autonomic symptoms (previously validated autonomic symptom score), as well as for chronic fatigue (chronic fatigue scale) and depressed moods (zung depression scale) [(mean age = 39 ± 2 years) (88% females: 12% males) (BMI = 27.5) (mean decrease in systolic blood pressure following bedside tilt of at least 20 mmHg with lack of an adequate tachycardic response) (expiratory: inspiratory RR ratio = 1.08 ± 0.1) (QTC = 430 ± 6 mmHg) [Dx of AN: autoimmune (n = 18): pure autonomic failure (n = 22): MVP (n = 10): other (n = 6)].

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296 Results: NOH also reported 73 ± 8% of other autonomic symptoms. Symptoms of peripheral neuropathy were common in NOH. Greater autonomic dysfunction correlated with symptoms of extreme tiredness (r2 = 0.5; P \ 0.04), and venous pooling (r2 = 0.5; P \ 0.05), as well as greater decreases in SBP after upright posture (r2 = 0.4; P \ 0.01). Patients with more autonomic symptoms had higher fatigue scores (r2 = 0.4; P \ 0.0000), and more depressed moods (r2 = 0.2; P \ 0.001). NOH with greater fatigue reported more depressed moods (r2 = 0.4; P \ 0.000). NOH also reported difficulty in functioning, being less mentally alert, problems thinking clearly, with the need to limit physical activities and workload, as well as more reliance on others, and therefore, decreased quality of life. Conclusion: Patients with NOH often have other symptoms of autonomic dysfunction, fatigue, and depressed moods, with decreased quality of life. Furthermore, these questionnaires can help to identify quality of life issues also important to younger patients with NOH.

Poster #17 Essential hypotension registry: psychometric measurements for anxiety, depression and coping strategies: hypotension is associated with depression and anxiety. Is there a psycho-biotype? Preliminary report L.E. Medina1, J. Ospina2, M.A. Lemos3, G. Cuartas3, J. Calle2, M. Gutierrez3, Y. Torres3 1 Neurocardiology Department and Non Invasive Cardiology Department, Clinica Medellin; 2 Research Group on Psychiatry, Universidad de Antioquia; 3 Mental Health Group, Universidad CES Objective: Life is stressful and is likely that the degree of stress responsivity and its possible implications for cardiovascular (CV) and psychiatric (PSYQ) pathologies seem to be linked to the individual strategy of coping with stressors. Experimental evidence support that in response to the same stressor the sympathetic activity may increase or drop. The hypothesis is that flight response has hypotension (HO) as a CV response and depression, higher anxiety scores and coping strategies showing evitation as PSYQ response; the opposite for hypertensive (HT). INTERHEART study showed stress as an important risk factor for CV disease. Methods: 106 HT and HO patients were evaluated. Zung scales for depression and anxiety (validated in Colombia), coping strategies scale of Chorot and Sandin (1993) and the big five questionnaire (BFQ) for personality were used. Psychologist and psychiatrist were blinded for patient’s BP group. Cardiologist was blinded for psychometric results. Results: 106 prospective and consecutive patients, 64% female, 56% HO. Depression (P \ 0.0018; OR: 4.2 [1.673–10.9155]), anxiety (P \ 0.016; OR: 2.75 [0.8306–8.6649]), emotional escaped (P \ 0.041), and positive re-evaluation (P \ 0.005), were more frequent in HO; problems solution (P \ 0.029) is more frequent in HT. Conclusions: Psychosocial stress factors play a significant role in the onset and progression of stress-related disorders, physiological and psychological in nature. The flight response through the Periaqueductal gray matter orchestrate a pain (opioid), blood pressure and heart rate (drops) and behavioral response. It is possible that HT individuals have CV diseases and HO individuals PSYQ disorders as depression as a stress response targets. Major depression is the leading cause of years lived with disability and ranks fourth in the ten leading causes of the global burden of disease. HT affects approximately 1 billion individuals Worldwide. Strategies directed to prevent

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Clin Auton Res (2009) 19:275–316 and control distress may become of paramount importance for community health policies.

Poster #18 Norepinephrine levels in pediatric postural tachycardia syndrome G. Chelimsky1, S. Madan2, D. Zhang2, T. Chelimsky2 1 Rainbow Babies and Children’s Hospital, Pediatric GI, USA; 2 Neurologic Institute, Autonomic Disorders, Cleveland, OH, USA Background: NE levels are thought to represent increasing sympathetic activity attendant to a stand, with levels doubling in normal subjects, and perhaps tripling in patients with POTS. We sought to verify this concept. Method: We identified pediatric patients with POTS referred to the autonomic laboratory, exhibiting an increase in heart rate by more than 30 bpm that was sustained and orthostatic symptoms, with available supine and standing NE levels. We used regression analysis, student’s t-test and v2 to correlate NE levels and other variables. Results: In 32 subjects, lying to standing NE ratios were 1.74 ± 0.51 (range 0.97–3.11); Supine levels 247 ± 122 pg/ml (100–577) and standing levels were 412 ± 217 (147–1,021). There was no significant relationship between supine NE levels and supine heart rate or between the standing values. The standing to lying ratio did not correlate with heart rate rise on tilt, and was not different if patients had syncope or abdominal pain as part of their complaints. A subgroup of 5 patients exhibited very high standing NE levels (575– 1021 pg/ml). These patients as a group had the highest 100 heart rate values (P \ 0.0004). However, only one of these patients had a high ratio (2.7), with the rest at or below 2. Conclusion: Baseline and standing NE levels do not correlate with supine or standing heart rates, respectively, and the change in heart rate does not correlate with the standing/supine NE ratio. The only finding was in a subset with high standing levels who also exhibited the highest heart rates. NE levels may not add much to the evaluation and diagnosis of pediatric patients with POTS.

Poster #19 Autonomic dysfunction in adolescents with irritable bowel syndrome (IBS) N. Raghunath, E. Rivera, A.J. Ocon, J.M. Stewart, M.S. Medow Department of Pediatrics, New York Medical College, Hawthorne, NY, USA Symptoms associated with irritable bowel syndrome (IBS) have been ascribed to autonomic nervous system dysfunction. In order to establish whether there are differences in autonomic function, the effects of head-up-tilt to 45
for 10 min (HUT45) and of static voluntary isometric exercise (Isometric Handgrip, IHG) from five subjects with IBS (15–20 years of age) and symptoms of orthostasis (lightheadedness, dizziness and mental clouding) were compared to normal healthy controls. IHG produces baroreflex independent sympathetic activation through central command, mechanoreflex and chemoreflex mediated mechanisms. Because many IBS subjects report an increase of symptoms following meals, we compared results obtained while fasting and 30 min after food ingestion. IBS subjects had a significantly higher resting HR than control (72.92 ± 5.21 vs.

Clin Auton Res (2009) 19:275–316 53.66 ± 1.76, P \ 0.05). HUT45 resulted in an increase in HR in both control and IBS, but this increase was significantly higher only in the IBS group where HR increased significantly (72.92 ± 5.21 vs. 88.64 ± 5.31, P \ 0.05). IHG in both groups caused an increase in blood pressure, and an increase in heart rate that remained significantly higher in IBS compared to control. Heart rate variability measurements were no different between groups while fasting, however postprandial values were significantly reduced for Heart Rate Variability (6,057 ± 748 vs. 2,495 ± 543), Low Frequency power (1,295 ± 82 vs. 643 ± 132) and High Frequency power (3,708 ± 689 vs. 1,412 ± 422), P \ 0.05, comparing control to IBS. These data suggest that control of autonomic function is altered in subjects with IBS and these changes can be accentuated by the ingestion of food.

Poster #20 Hypovitaminosis D in postural tachycardia syndrome (POTS) in adolescents I.T. Jarjour, L.K. Jarjour Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA Objective: To investigate whether POTS is associated with hypovitaminosis D (HVD). Methods: 32 children evaluated in 2007 and 2008 for probable POTS by a standing or tilt test or both at a tertiary care Pediatric Neurology Clinic were included in a retrospective study after IRB approval. We measured serum 25-hydroxy vitamin D levels and defined HVD as 25 OH D B 32 ng/mL, vitamin D deficiency as \20 ng/mL (Pediatrics 123:797, 2009; J Nutrition 135:317, 2005), and POTS as two or more symptoms of orthostatic intolerance [3 months and increased HR of [30 BPM or HR of [120 BPM within 10 min of standing or 70
tilt. Results: 24 children had POTS, ages 12–18 years, 17 (71%) were females. Serum 25 OH D levels ranged from 7 to 40 (mean of 24) ng/ mL. The prevalence of HVD was 84 and 32% of patients had vitamin D deficiency. Only 14% of a multiracial US adolescent population has vitamin D deficiency. Vitamin D deficiency was statistically associated (P = 0.03, v2) with cognitive symptoms, such as brain ‘‘fog’’ and poor memory, which were reported in half the subjects. The prevalence of chronic fatigue (75%), GI symptoms (71%), migraine (58%), sleep disorder (50%), anxiety disorder (37%), syncope (33%), and attention-deficit disorder (33%) did not correlate with vitamin D deficiency, although ADHD approached significance (P = 0.06). Conclusions: HVD is associated with POTS in adolescents and is a potentially pathophysiologic factor in POTS, particularly in patients with cognitive symptoms.

Poster #21 Nutritional correlates of orthostatic intolerance and chronic fatigue R.M. Antiel, J.S. Caudill, B.E.U. Burkhardt, C.K. Brands, P.R. Fischer Department of Pediatric and Adolescent Medicine, Division of General Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN, USA Background: Approximately 1% of adolescents suffer from disability due to chronic fatigue and/or orthostatic intolerance. Adult studies show correlations between iron insufficiency and fatigue as well as between hypovitaminosis D and non-specific pain.

297 Methods: Records of 206 adolescents who presented to a general pediatric referral clinic with symptoms of fatigue and/or orthostatic intolerance were analyzed. Results: The mean age of patients was: 15 + 2 years (73% female). Commonly reported symptoms included dizziness (84%), fatigue (71%), headaches (63%), and nausea (54%). Of the 206 patients, 188 (91%) underwent autonomic reflex screening, including a head-up tilt test (HUT). On HUT 130 patients (69%) had excessive postural tachycardia (PT) with a heart rate (HR) change of [ 30 bpm. The body mass index (BMI) was 22 + 4 kg/m2 (n = 201). BMI correlated with both VO2max (r = 0.38, P \ 0.001) and HR change during HUT (r = -0.2, P \ 0.01). The mean serum ferritin was 31 lg/L (n = 131, SD = 40). Of the patients with PT, 56% had low iron stores (serum ferritin B 25 lg/L) and 23% of these patients were iron deficient (serum ferritin \ 12 lg/L). In contrast, of the patients without PT, 28% had low iron stores and 20% of these patients were iron deficient. HR change did not correlate to ferritin level (P = 0.15). The mean vitamin D level was 29 ng/ml (n = 95, SD = 12). 21 patients (22%) had hypovitaminosis D (25-hydroxyvitamin D \ 20 ng/mL). The prevalence of hypovitaminosis D was 30% among patients with PT, compared to 10% among patients without PT. PT and hypovitaminosis D were correlated (P = 0.024). Conclusion: In patients presenting with chronic fatigue and/or orthostatic intolerance, low ferritin levels and hypovitaminosis D are common, especially in patients with PT. Further studies of the pathogenesis of chronic disabling symptoms in adolescents and of nutritional therapies are needed.

Poster #22 Sleep patterns in children with autonomic disorders compared to children with organic gastrointestinal illness S. Safder1, C. Rosen2, G. Chelimsky1 1 Department of Pediatric Gastroenterology, Case Medical Center, Rainbow Babies and Children Hospital, Cleveland, OH, USA; 2 Department of Sleep Medicine, Case Medical Center, Cleveland, OH, USA Background: Sleep disturbances have been documented in chronic childhood illnesses associated with chronic pain. Insufficient sleep has been shown to increase the perception of pain. Children with autonomic disorders are a unique patient population with complaints of functional abdominal pain. Evidence suggests that patients diagnosed with functional gastrointestinal disorders (FGID) and dysautonomias have higher rates of pain and discomfort and report significant sleep difficulties and fatigue when compared to those of healthy individuals. The purpose of this study is to determine if the sleep abnormality in children with autonomic disorders and FGID is a consequence of pain or perhaps produced by an autonomic dysregulation. Aim: To describe the sleep habits and prevalence of sleep complaints in children with autonomic disorders compared to children with chronic organic gastrointestinal illness such as IBD, constipation, reflux, eosinophilic esophagitis, etc. Materials & methods: An IRB approved prospective study was conducted in the GI department. Children [7 years of age, with normal mental and developmental state for age who were patients of the autonomic clinic or the general GI clinic were approached for participation in this study. Families completed two validated questionnaire about sleep habits (children sleep habit questionnaire, CSHQ) and sleepiness (epworth sleepiness scale-EES, pediatric

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298 modification). Data was compared between the two groups and to national data in teen-age children. Results: Forty participants were recruited: autonomic disorders (n = 17), chronic organic GI illnesses [n = 23 including 14 with inflammatory bowel disease (IBD)]. Mean age was 13.5 + 3.7 years; male 19 (48%). Children with FGID and autonomic dysfunction had significantly more complaints in the domain of insomnia and obstructive sleep apnea (OSA). In addition, they had more complaints of night awakening and difficult waking in the morning compared to children with organic GI disorders. Both groups showed similar frequency of insufficient sleep time, which did not differ from the national data. Both groups also had similar frequency of school absence and poor sleep hygiene; however, this was higher in both groups compared to national averages. Conclusion: Children with FGID and autonomic dysfunction have more significant sleep complaints than children with organic GI disorders. Speculation: The more significant sleep dysfunction in children with FGID may be part of the multisystem complaints seen in this patient population. Involvement of the autonomic nervous system which is known to contribute to sleep regulation may play a role. Alternatively, insufficient sleep and sleep disturbances also affect the ability of these children to cope with chronic pain issues that many of them experience.

Poster #23 Acquired orthostatic intolerance and alpha-3 ganglionic acetylcholine antibodies in an adolescent girl H.R. Murali1, K.J. Mack2, N.L. Kuntz2 1 Department of Neurology, Marshfield Clinic, Marshfield, WI, USA; 2 Department of Neurology, Mayo Clinic, Rochester, MN, USA The patient was a 15 year old previously healthy girl who presented with subacute onset of headache and orthostatic intolerance. One month prior to onset, she had been started on escitalopram oxalate for relief of irritability and depression without intercurrent illness. Patient reported onset of holocephalic headaches, nausea, poor concentration and dizziness worse with upright posture. Over 2 weeks, she became unable to sit upright or stand due to incapacitating lightheadedness with a tendency to fall if she attempted to remain upright. General and neurologic examinations were reportedly normal. Initial diagnostic testing demonstrated normal peripheral blood counts, chemistries, cerebrospinal fluid and magnetic resonance head imaging. Blood Lyme serology demonstrated antibodies only to the 18 kDa protein. Empiric treatment with 6 weeks of doxycycline for neuroborreliosis did not improve symptoms. Neurologic reevaluation demonstrated normal pupillary responses, sweating, saliva production, bowel sounds, mental status, cranial nerve examination, muscle strength and small and large fiber sensory testing. Tilt test was abnormal. Supine blood pressure and pulse were 95/71 and 68 with a 65
head up tilt producing a change to 52/42 and 142. Associated upright symptoms included blurred vision, sweating and subjective feelings of being ‘‘hot and lightheaded’’. Beat-to-beat heart rate variation was decreased. Cardiac response to Valsalva maneuver was abnormal. Other components of the autonomic reflex screen were normal. Paraneoplastic antibody screen was normal except for an elevated alpha-3 ganglionic acetylcholine receptor antibody (0.12 nmol/L with normal \ 0.02 nmol/ L). Normal testing included electrocardiogram, electroencephalogram, thyroid functions, fractionated free plasma catecholamines, cortisol, and hemoglobin. Patient was treated symptomatically with

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Clin Auton Res (2009) 19:275–316 increased salt and fluid intake, alpha adrenergic agonist and beta blockers and acetylcholinesterase inhibitors. Two intravenous infusions of immunoglobulin were administered. Clinical followup over 2 years demonstrated gradual resolution of symptoms without identification of an underlying neoplasm.

Poster #24 Hyperventilation induced neurally mediated syncope S. Dietz1, J. Sanders1, P. Thakker2, H. Vyas3, W.P. Whitehouse1,4 1 Section of Human Development, University of Nottingham, Nottingham, UK; 2 General Paediatrics and Paediatric Cardiology; 3 Respiratory Paediatrics and Paediatric Intensive Care; 4 Paediatric Neurology, Nottingham University Hospitals NHS Trust, Nottingham, UK Introduction: Neurally mediated syncope (NMS) is the most common cause of transient loss of consciousness (TLOC). Different triggers can induce NMS, including the Valsalva manoeuvre and the head-up tilt test (HUTT). The role of hyperventilation in triggering NMS or TLOC is controversial. Case report: We describe a 14 year old girl with a mixed NMS response (both hypotension and bradycardia) induced by hyperventilation during an assessment for the evaluation of her TLOC. Blood pressure (BP) and Heart rate (HR) were continuously measured using a beat-to-beat finger plethysmographic device (Finometer), together with video, electroencephalography (EEG), electrocardiography (ECG) and respiratory movement. 40 s after the beginning of the seated protocol hyperventilation exercise, she began to sway and reported feeling ‘‘dizzy’’. This corresponded with systolic BP drop of 32 mmHg and a diastolic BP drop of 36 mmHg (compared to after 1 min of sitting down). At the same time, the HR fell by 42–33 bpm. 40 s after the beginning of the symptoms, the girl collapsed unconscious. The systolic BP had dropped another 8 mmHg while the diastolic BP had increased a little by 6 mmHg. The heart rate had dropped to 28 bpm. After 20 s, she opened her eyes again and after 60 s she said that she felt better again. Her heart rate had then increased again to 92 bpm. Background: EEG remained normal throughout this brief episode. Conclusion: Hyperventilation can induce a mixed (vasodepressor and cardioinhibitory) NMS. The TLOC was not associated with a slow EEG but was brief and the physiological changes in BP and HR significant. The episode may have actually been a pre-syncope rather than established syncope.

Poster #25 Panic attack and neurally mediated syncope in the same patient J. Sanders1, S. Dietz1, W.P. Whitehouse1,2 1 Section of Human Development, University of Nottingham, Nottingham, UK; 2 Department of Paediatric Neurology, Nottingham University Hospitals NHS Trust, Nottingham, UK Introduction: The co-existence of epilepsy and psychogenic nonepileptic attacks in young people is well described. We felt that young people with neurally mediated syncope (NMS) were similarly at risk

Clin Auton Res (2009) 19:275–316 of developing psychogenic or functional transient loss of consciousness (TLOC). Case report: A 16 year old male experienced separately a panic attack and a NMS episode during assessment for his TLOC. Blood pressure (BP) and heart rate (HR) were measured continuously using a beat-tobeat finger plethysmographic device (Finometer), together with video, EEG, ECG and respiratory movement. 1 min 40 s into a 5 min standing phase, his BP began to drop. Over 3 min, the systolic BP dropped 77 mmHg, the diastolic BP dropped 41 mmHg. The heart rate did not decrease significantly. The patient then had a ‘funny feeling’ and needed to sit down after which the BP recovered and symptoms resolved. The assessment then included a head-up tilt test (HUTT). 3 min and 55 s into the head-up tilt he developed similar pre-syncope symptoms again of his arms and legs feeling ‘funny’. This brought on an episode of hyperventilation and distress, causing his respiratory rate to increase to 1 breath per second. He then developed a headache and felt ‘really hot’. His heart rate went up by 70 to 130 bpm. His blood pressure slightly fell at the beginning of the episode (not enough to qualify for a vasodepressor response), but increased when the patient became distressed. The tilt was stopped when he collapsed into tears and trembling. During one assessment, this patient had both a vasodepressor pre-syncope on standing and a panic attack with similar pre-syncopal symptoms during a HUTT. Conclusions: This confirms our previous clinical impression, and suggests that the psychogenic or functional collapse was adaptive in maintaining his BP and preventing a vasodepressor syncope.

Poster #26 Autonomic and neuroendocrine features of familial Panayiotopoulos syndrome A. Gonzalez Duarte, L. Norcliffe-Kaufmann, J. Martinez, F. Axelrod, H. Kaufmann Dysautonomia Research Laboratory, Department of Neurology, New York University School of Medicine, New York, NY, USA Panayiotopoulus syndrome is a benign childhood epilepsy characterized by altered autonomic activity (vomiting, diaphoresis, pallor and pupillary changes) at seizure onset. Interictal EEG shows highamplitude sharp and slow wave complexes. The cardiovascular and neuroendocrine features of a typical seizure have not been described. Three siblings with Panayiotopoulus syndrome underwent 24-h EEG recording and head-up tilt with blood pressure and RR interval monitoring. Plasma catecholamines and vasopressin were measured supine, upright and during typical symptoms. Patient 1 (12-year old, girl) had a history of involuntary lacrimation, abdominal pain, restless legs at night, and recurrent episodes of frontal headache with brief loss of muscle tone and unresponsiveness followed by somnolence. Her EEG revealed bilateral frontotemporal spikes. Prolonged tilt failed to induce symptoms. Patient 2 (10-year old, boy) had type-1 diabetes since age 7. He suffered episodic headaches with pinpoint pupils, skin flushing of face, trunk and extremities, purple skin in hands and feet, diaphoresis, nausea and vomiting. During a typical episode, he had elevated serum glucose (206 mg/dl). Prolonged tilt triggered typical symptoms after 9 min; there was a small increase in BP (+5/4 mmHg, SAP/DAP), a pronounced increase in HR (+59 bpm), and norepinephrine (+242 pg/mL), epinephrine (+175 pg/ mL) and vasopressin (+22.1 pg/mL) concentrations. His EEG revealed right temporal and parietal spikes. Patient 3 (8-year old, boy) had a history of restless leg at night, enuresis, night terrors, visual hallucinations, cyclic abdominal pain and nausea. His EEG showed bitemporal spikes. He had no symptoms during tilt testing. Autonomic

299 testing was otherwise normal in the three siblings. Hypertension, tachycardia and the release of vasopressin suggest activation of the central autonomic network during seizures in familial Panayiotopoulos syndrome. These autonomic and neuroendocrine features may be useful in the diagnosis and may have therapeutic implications.

Poster Session II Poster #27 Plethysmography improves interpretation of the blood pressure response to the Valsalva maneuver F. Fouad-Tarazi, R. Shields, F. Jaeger, R. Christian Center for Syncope and Autonomic Disorders, The Cleveland Clinic, Cleveland, OH, USA The Valsalva maneuver [VM] is a valuable component of cardiovascular autonomic reflex testing. We hypothesized that plethysmography-derived vascular resistance [PDVR] during VM provides more accurate interpretation of the BP response to the VM [BPRVM]. We reviewed retrospective data in 265 patients who had cardiovascular autonomic testing in our lab in 2007–2008 including VM with simultaneous calf arterial plethysmography. VM was done using beat-to-beat blood pressure [BP] and heart rate [HR] measurements. BPRVM was 1) Normal [n = 156] with BP plateau in late phase II [Ph II] and BP overshoot [OS] in phase IV [Ph IV], 2) Abnormal [n = 32] if decline of BP in late Ph II and no BP OS in Ph IV, or 3) Equivocal [n = 77] if BP responses were discordant, mostly BP plateau in late Ph II with no OS in Ph IV. The increase in PDVR in late Ph II versus baseline [Resistance Ratio] was normal if C1.6. The HR ratio in Ph IV/ late Ph II [HRR] was normal if B0.85. HRR was normal in 129 (83%) with normal BPRVM, abnormal in 26 (81%) with abnormal BPRVM, and abnormal in 61 (79%) with equivocal BPRVM. The PDVR was normal in 114 (73%) with normal BPRVM, abnormal in 21 (65%) with abnormal BPRVM, and abnormal in 48 (62%) with equivocal BPRVM. PDVR appears more sensitive than BPRVM in detecting abnormal sympathetic response to the VM (27% abnormal with normal BPRVM). Compared to the HRR, the PDVR is not influenced by BP response in Ph IV. In addition, the PDVR is useful in identifying patients with apparently abnormal BPRVM who do not have evidence of arterial vasoconstriction (35% with abnormal BPRVM and 38% with discordant BPRVM) and may have nonneurogenic mechanisms for the abnormal BPRVM, such as poor arterial compliance or excessive venous pooling.

Poster #28 Autonomic function is preserved in the majority of male and female Fabry patients M. Biegstraaten1, I.N. van Schaik1, W. Wieling2, F.A. Wijburg3, C.E.M. Hollak4 1 Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands; 2 Department of Internal Medicine, Division of Cardiology, Academic Medical Center, Amsterdam, The Netherlands; 3 Department of Pediatrics, Emma Children’s Hospital, Academic Medical Center, Amsterdam, The Netherlands; 4 Department of Internal Medicine, Division of Endocrinology and Metabolism, Academic Medical Center, Amsterdam, The Netherlands

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300 Autonomic dysfunction is considered to be an important feature of Fabry disease. However, only a few studies addressing autonomic dysfunction in Fabry disease have been performed. We studied a large cohort (48 patients, 15 males, 30 females and 3 children; 69% of the known Dutch Fabry patients) to establish malfunctioning of the autonomic nervous system using the Autonomic Symptom Profile (n = 48) and cardiovascular function tests (heart rate response induced by forced breathing (FRSA) and standing up test (deltaHRmax), blood pressure response on standing (OH) (n = 36). The Autonomic Symptom Profile revealed a significantly higher sum score in Fabry patients than in healthy control subjects, but much lower than has been described in patients with proven autonomic failure. The autonomic function tests revealed only mild abnormalities. FRSA was abnormal in 3/36 patients and deltaHRmax in 2/ 36 patients. OH was not present. None of the patients showed more than one abnormal test result. In conclusion, we found only limited evidence for the presence of autonomic dysfunction in Fabry disease. We hypothesize that end-organ abnormalities known to be present in Fabry disease play an important role in the clinical presentation.

Poster #29 Autonomic modulation is not altered in mitochondrial myopathy M.N. Bartels1,2, R.E. Gerardo1, K. Engelstad3, R. De Meersman1,2, P. Kaufmann3 1 Department of Rehabilitation Medicine, Columbia College of Physicians and Surgeons, Columbia University, New York, NY, USA; 2 Department of Biobehavioral Sciences, Teachers College, Columbia University, New York City, NY, USA; 3 Department of Neurology, Columbia College of Physicians and Surgeons, Columbia University, New York, NY, USA Introduction: Mitochondrial myopathy is a rare condition which has many systemic effects, including muscle weakness, hearing loss, and central neurological changes. We evaluated 5 individuals with mitochondrial myopathy (MM) and five age, gender and BMI matched deconditioned normal controls (NC) for resting heart rate and exercise responses. Methods: Heart rate data were recorded from standard 12 lead recordings with 500 Hz samples for 5 min at rest. Post hoc analysis was done with time frequency analysis using customized programs written in Labview v8.0. Statistics: T tests were performed with probability level set at P \ 0.01. Since the group sizes were so small, Cohen’s Effect size estimates were performed on all variables. Results: Mean age, BMI and gender were the same between groups. A trend (with marked effect) toward lower peak exercise capacity was seen in MM versus NC in VO2 [MM 1.10 (0.41) L02/min vs. NC 1.63 (0.46) L02/min P \ 0.15, effect size 1.24, Cohen’s D] and wattage [MM 69 (23) Watts vs. NC 125(54) Watts P \ 0.10, effect size 1.34, Cohen’s D]. Resting heart rate, blood pressure, and respiratory rate were the same between groups. Intriguingly, there were no significant differences in autonomic modulation measured with heart rate variability between the groups as measured by LF [MM 60.8 nu (11.2) vs. NC 59.4 nu (9.5)], HF [MM 37.4 nu (12.4) vs. NC 39.0 nu (9.5)], or with the LF/HF ratio [MM 1.86 (0.92) vs. NC 1.68 (0.84)]. Conclusion: Despite significant alterations in mitochondrial metabolism and trends to lower peak exercise capacity with significant effect differences, individuals with mitochondrial myopathy do not demonstrate any alteration in resting autonomic indices when compared to matched controls. Further work to evaluate autonomic responses with

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Clin Auton Res (2009) 19:275–316 exercise may show changes under stress. Supported by the VIDDA foundation and Penwest Corporation.

Poster #30 Essential hypotension registry: sympathovagal balance at 24 h, day and night in ambulatory Holter monitoring according to blood pressure groups in real-life settings L. Medina1, M. Duque1, J. Marin1, E. Gonzalez1, V. Astudillo1, J. Aristizabal1, J. Bernal1, M.A. Restrepo1, A. Arroyave1, G. Jaramillo1, Y. Torres2, W. Uribe1 1 Cardiology, Electrophysiology and Neurocardiology Department, Medellin Clinic, Medellin, Colombia; 2 CES University, Medellin, Colombia Objective: Sympathetic nervous system (SNS) is pivotal to short-term regulation of blood pressure (BP), their importance in long-term is less clear. SNS may produce hypertension by increase vascular tone, renal sodium and water retention and inducing cardiac and vascular remodeling. Are there SNS different between groups of blood pressure? Methods: Individuals classified according to their BP (Physical examination and/or ambulatory 24 h BP monitoring) in normotension (NO), hypertension (HT) and hypotension (EHO) according to well accepted criteria, older than 19 and younger than 61 years old, with holter monitoring with at least 18 h of recording, during daily life activities (real-life settings) out of medication with autonomic effect. Normalized units were used for low and high frequency to calculate sympathovagal balance (SVB). Results: 382 individuals, 71.2% female. SBV is significant different (W) between male and female at 24hs, day (D: 6–22 hs) and night (N: 22–6 hs): 4.18 vs. 3.17; 4.93 vs. 3.81 and 3.51 vs. 2.71, SVB increase significantly as aging. BMI has not effect on SVB. SVB according to the BP group: at 24hs: NO: 3.73 (3.3692–4.0769); HT 3.98 (3.5769–4.3941); EHO 3.04 (2.7600–3.3245) (W EHO vs. N and HT); D: NO 4.4 (4.0361–4.7815), HT 4.56 (4.1370–4.9922), EHO 3.75 (3.4602–4.0398) (W EHO vs. N and HT); N: NO 3.16 (2.7979– 3.5277), HT 3.47 (3.0504–3.8943), N 2.5 (2.2139–2.8019) (W EHO vs. N and HT). There are not significant differences in heart rate between groups. Conclusions: These results support the hypothesis that SNS plays a role in BP regulation in real-life, long-term settings. Cardiovascular reactivity through the SNS is hypothesized to mediate the relationship between stress and cardiovascular diseases. Differences in SNS between HT and EHO may explain why some pathologies like syncope are more frequent in EHO. Syncope patients have less sympathetic tone and a striking drop preceding syncope episode.

Poster #31 Essential hypotension registry. Cardiovascular reactivity: a search for the integration of the neurocardiovascular relationship and their association with glucose challenge and depression L. Medina1, 2 Cardiology, Electrophysiology and Neurocardiology Department, Medellin Clinic, Medellin, Colombia; 2 CES University, Medellin, Colombia

1

Clin Auton Res (2009) 19:275–316 Objective: Classic risk factors are limited in predicting individual risk. This has stimulated further research like the response to psychosocial environment. Stress is an important cardiovascular (CV) risk factor. Central regulatory circuitries and the autonomic nervous system are primary candidates to drive cardiovascular reactivity (CVR). Phenomena as syncope or sudden cardiac death are paroxysmal in their nature and are difficult to predict with currents models. Reactivity may occur at different settings: Frank Starling law is reactivity to myofibril stretching, orthostatic hypotension is reactivity to a gravity challenge, and blood/injury phobia involved the brain. Methods: CVR definition: (A) Hypo-reactive (HoRx) one of: (1) symptoms: syncope and/or dizziness with: prolonged standing (at religious service, parade, etc), blood/injury phobia or pain; (2) neurally mediated syncope (Calgary score [ -2 and/or positive tilt table testing), (3) hypotension: [ 20 mmHg or [ 10 mmHg drop in systolic (S) and/or diastolic (D) blood pressure (BP) within 3 min of standing any combination of (1), (2) or (3); (B) Normo-reactive (NRx): normotensive, (C) hyper-reactive (HTRx): hypertensives. Several variables were looked for differences between these CVR groups. The 2 h 75 g. oral glucose challenge/basal glucose (GluChR) was evaluated. Hypothesis: (1) HoRx are associated with lesser GluChR (drop in BP associated to glucose drop); (2) HoRx has a higher OR than EHO for depression. Results: 865 GluChR values were evaluated. For CVR: HTRx: 1.14; NRx: 1.07; HoRx: 1.03 [significant (W) HoRx vs. HTRx]; for tension group: hypertension (HT) 1.17; normotension (N) 1.08; essential hypotension (EHO) 1.04; (W HT vs. EHO). Depression (106 individuals): EHO has a 4.2 (1.617–10.915) OR versus HT for depression; HoRx has a 5.9 (1.666–21.05) OR versus HTRx. Conclusions: This preliminary data are promising. The main purpose is to describe some CVR variables being search in the EHO registry. Aging processes may change CVR classification.

Poster #32 HIV/AIDS leads to early cardiovascular autonomic neuropathy P. Nemechek1, S. Ghosh-Dastidar2, J. Colombo2 1 Nemechek Health Renewal, Kansas City, MI, USA; 2 ANSAR Medical Technologies, Inc., Philadelphia, PA, USA Introduction: Chronic disease is known to lead to early cardiovascular autonomic neuropathy (CAN). CAN indicates risk for sudden cardiac death (SCD). Autonomic dysfunction (AD), defined as abnormal autonomic or sympathovagal balance (SB, normal = 0.4 \ SB \ 3.0) prior to CAN is asymptomatic. AD is associated with greater morbidity and mortality. Early intervention provides Physicians with more therapy options. Treating AD by restoring balance between parasympathetics (P) and sympathetics (S) reduces morbidity and mortality. CAN with high SB indicates high risk of SCD. Early intervention, based on early testing is justified based on the diagnosis of chronic diseases, like HIV/AIDS. Our hypothesis is that HIV/AIDS leads to early AD. Methods: Autonomic profiling of 232 consecutive patients (47 Female) was performed with ANSAR (Philadelphia, PA) at an ambulatory clinic in Missouri. HR variability and respiratory activity data were collected concurrently, and analyzed independently and simultaneously to compute P&S activity. The results were analyzed and presented here against 234 aged-matched normals from our nation-wide database. Results: CAN is defined as P \ 0.1 bpm^2. Upon first diagnosis (approximately age 25 on average), patients’ autonomic levels are

301 near normal with SB (1.77). Within one decade, patents are near CAN, presenting with advanced AD and high SB (5.30). At age 55, patients present with CAN with continued high SB (3.60). Normal subjects present with CAN around age 75, yet with normal SB (1.66) which mitigates the risk. Conclusions: Patients present earlier than normals with AD and CAN. Patients also present with high SB as compared with normal suggesting that patients are at higher risk for SCD, increased morbidity, and greater healthcare costs.

Poster #33 Early autonomic dysfunction is associated with secondary hypertension in HIV/AIDS patients P. Nemechek1, S. Ghosh-Dastidar2, J. Colombo2 1 Nemechek Health Renewal, Kansas City, MO, USA; 2 ANSAR Medical Technologies, Inc., Philadelphia, PA, USA Introduction: Chronic disease, including HIV/AIDS leads to early autonomic dysfunction (AD), defined as abnormal autonomic or sympathovagal balance (SB, normal = 0.4 \ SB \ 3.0) prior to autonomic neuropathy. AD is associated with greater morbidity (gastrointestinal upset, urogenital disorders, dizziness and lightheadedness, and secondary hypertension) and mortality. Early intervention restores balance between parasympathetics (P) and sympathetics (S) and reduces co-morbidities. We hypothesis that HIV/AIDS induced autonomic imbalance leads to secondary hypertension. Methods: Autonomic profiling of 232 consecutive patients (47 female) was performed with ANSAR (Philadelphia, PA) at an ambulatory clinic in Missouri. HR variability and respiratory activity data were collected concurrently, and analyzed independently and simultaneously to compute P&S activity. Patients were administered standard autonomic testing, including paced breathing (deep breathing or DB) and a series of short Valsalva maneuvers (V). BP was recorded during each phase of the clinical exam. The DB&V results were analyzed and presented here against 234 aged-matched normals from our nation-wide database. Results: Weak DB&V responses are early indicators of AD. P response to DB decreases (age 25) about a decade earlier than the S response to V decreases (age 35). The resulting discrepancy results in a sympathetic excess (SE). By age 45, the patients’ autonomic levels are below normals’. SE can be associated with (pre-)hypertension and hypertension. By age 35, the average BP was elevated by 20.3/ 1.5 mmHg to 146.4/77.6 and by age 45 resting BP was up to 151.9/ 77.9, therapy at this time normalizes BP by age 55 (137.0/75.5). The patients’ BPs are higher than normals’. Conclusions: Early AD, in this case SE, is associated with hypertension.

Poster #34 Factitious recurrent tachyarrhythmias with cardiac enzyme elevations A. Gonzalez Duarte, L. Norcliffe-Kaufmann, J. Martinez, H. Kaufmann Dysautonomia Research Laboratory, Department of Neurology, New York University School of Medicine, New York, NY, USA

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302 We present the case of a woman who surreptitiously self injected epinephrine leading to dangerous ventricular tachyarrhythmias. A 36year old female nurse working in an allergy clinic had a history of multiple hospitalizations for hypertensive crisis and chest pain. Her hypertensive episodes were accompanied by headache, vomiting, tachycardia and diaphoresis with marked elevations of troponin I (9.5–9.7 ng/mL; n:0–2.0), CKMB (9.6 ng/mL; n:0–6.9), hyperglycemia (154–271 mg/dl) and hypokalemia (2.9–3.0 meq). She had a dual-chamber implantable defibrillator inserted, radiofrequency ablation of the AV junction and was being treated with carvedilol. She was referred to our laboratory for autonomic testing. Before testing, she asked to use the bathroom, when coming out she looked pale, anxious, clammy and vomiting. 10 min later, she complained of severe chest pain and palpitations. Her blood pressure was 210/135 mmHg with a heart rate of 85 bpm. Her EKG showed multiple fusion and premature atrial complexes with aberrant conduction. After 50 min, her blood pressure decreased spontaneously to 122/69 mmHg. Repeated venous blood samples showed an initial level of epinephrine of 7,496 pg/ml. 10 min later the level was 25,359 pg/ml and after 60 min it decreased to 4,038 pg/ml. Norepinephrine levels were consistently normal (134, 243, 305 pg/ml), and so were plasma metanephrines (29 pg/ml) and normetanephrines (196 pg/mL). Urinary VMA was normal (5.8 mg/24hrs) and abdominal MRI and 1 3 1 I-metaiodobenzy-guanidin scintigraphy ruled out pheocromocytoma. This case could have been confused with a rare epinephrine secreting pheocromocytoma. However, the normal metanephrines ruled out this diagnosis. Surreptitious self injection of epinephrine should be considered in psychiatrically disturbed individuals.

Poster #35 Modelflow underestimates cardiac output in heat stressed humans C.G. Crandall1,2, T.E. Wilson3, M. Bundgaard-Nielsen4, T. Seifert4, N.H. Secher4 1 Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas, Dallas, TX, USA; 2 Department of Internal Medicine, University of Texas Southwest Medical Center at Dallas, Dallas, TX, USA; 3 Departments of Biomedical Sciences & Specialty Medicine, Ohio University College of Osteopathic Medicine, Athens, OH, USA; 4 Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark Estimation of cardiac output can be obtained from the finger pressure profile using the Modelflow method. However, the assumptions associated with Modelflow calculation of cardiac output may not be valid during heat-induced changes in the peripheral vasculature. This project tested the hypothesis that cardiac output obtained via Modelflow will accurately track thermodilution derived cardiac output. Nine healthy male subjects were instrumented with pulmonary artery catheters for the measurement of thermodilution derived cardiac output and blood temperature. Modelflow derived cardiac output was obtained from the FinometerTM pressure profile. Measurements were obtained during baseline and 30 mmHg lower-body negative pressure (LBNP) when subjects were normothermic and heat stressed (increase internal temperature * 1.2
C via water perfused suits). Data are reported as mean ± SD. There were no differences between Modelflow and thermodilution measures of cardiac output while

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Clin Auton Res (2009) 19:275–316 subjects were normothermic (thermodilution: 6.4 ± 0.3 l/min; Modelflow: 6.3 ± 0.4 l/min; P = 0.69); moreover the reduction in cardiac output to 30 mmHg LBNP were not different between methods (thermodilution: 1.4 ± 0.6 l/min; Modelflow: 1.1 ± 0.9 l/min; P = 0.35). While heat stressed, cardiac output was greater when measured with thermodilution (10.9 ± 0.7 l/min) relative to Modelflow (7.8 ± 0.5 l/min; P = 0.001). The values for cardiac output obtained via thermodilution in heat stressed subjects are comparable to cardiac outputs reported by others using dye dilution and soluble gas rebreathing techniques. While heat stressed, the reduction in cardiac output to 30 mmHg LBNP was greater when evaluated via thermodilution (3.8 ± 1.1 l/min) relative to Modelflow (1.5 ± 0.9 l/min; P \ 0.001). These data suggest that the Modelflow does not accurately measure cardiac output in the heat stressed human. Although the reduction in cardiac output measured with Modelflow during LBNP accurately track thermodilution derived cardiac output when subjects are normothermic, when heat stressed the reduction in Modelflow-derived cardiac output underestimates the actual reduction in this variable. Project supported by NIH: HL61388 and GM068865.

Poster #36 Immediate hemodynamic and sympathetic responses to coffee D.L. Jardine, J.M. Butler Department of General Medicine, Christchurch Hospital, New Zealand Introduction: Caffeine causes an acute rise in blood pressure, but the exact mechanism of this effect is not fully understood. Activation of the sympathetic nervous system is one possibility, but there have been few accurate studies of this hypothesis. A previous study found that decaffeinated coffee [decaff] could also cause sympathetic activation and so concluded that the hypertensive response may be secondary to substances other than caffeine. The aim of this study is to clarify the role of caffeine in the activation of the sympathetic nervous system and the acute hypertensive response to coffee. Methods: Healthy subjects were recorded continuously in the horizontal position for 120 min following the ingestion of decaff [n = 16, mean age 33 ± 3 years, caffeine dose 2 mg], regular coffee [n = 14, 33 ± 3 years, 200 mg], or water [n = 11, 34 ± 3 years]. Serum caffeine levels were measured, and 5 min samples of mean blood pressure [MBP], heart rate [HR], muscle sympathetic nerve activity [MSNA bursts/min and burst area/min], and stroke volume [SV] were averaged, at 15 min intervals. Results: Following decaff, MBP and MSNA [bursts/min] increased from 93 ± 3 mmHg to 101 ± 2 [P = 0.001] and 21 ± 2 bursts/min to 24 ± 2 [P = 0.04] respectively, but HR remained constant at 65 ± 3 bpm [P = 0.2]. Following regular coffee, MBP also increased from 91 ± 3 mmHg to 102 ± 3 [P = 0.001] but HR and MSNA remained constant at 64 ± 5 bpm [P = 0.09] and 23 ± 2 bursts/min [P = 0.43]. There was a trend towards increased SV in the regular group [110 to 124 units, P = 0.26]. For all variables, there were no differences between groups with time. Conclusion: Ingestion of coffee causes a progressive increase in BP over the subsequent 120 min, but the mechanism for this is uncertain. Decaff coffee activates peripheral sympatho-vasoconstriction, whereas regular coffee may have more cardiac effect.

Clin Auton Res (2009) 19:275–316

Poster #37 Melatonin attenuates the vestibulosympathetic reflex in humans J.S. Cook2, C.A. Ray1,2 1 Penn State Heart and Vascular Institute; 2 Department of Cellular and Molecular Physiology Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey, PA, USA Melatonin has been reported to decrease the nerve activity of medial vestibular nuclei in rats and is associated with an attenuated muscle sympathetic nerve activity (MSNA) response to baroreceptor unloading in humans. The purpose of this study was to determine if melatonin alters the vestibulosympathetic reflex in humans. To test this hypothesis, we recorded arterial blood pressure, heart rate, and MSNA in 13 healthy subjects (28 ± 1 years; 6 male, 7 female) during baseline and head-down rotation (HDR). Each subject randomly ingested either melatonin (3 mg) or placebo (sucrose) and was tested 45 min later. Subjects returned at least 2 days later to repeat the other trial. Melatonin significantly increased MSNA during baseline as compared to placebo (11 ± 2 and 9 ± 1 bursts/min, respectively; P \ 0.05). However, melatonin significantly attenuated MSNA responses during HDR as compared to placebo (D4 ± 1 and D6 ± 1 bursts/min, respectively; P \ 0.05). Heart rate and mean arterial pressure responses were not significantly altered by melatonin during HDR (D2 ± 1 beats/min and D-1 ± 1 mmHg, respectively). These results suggest that melatonin attenuates sympathetic responses to the activation of the otolith organs in humans.

Poster #38 Evaluation of a novel non model driven assessment of cardiac autonomic activity: response to initiation and termination of head-up tilt (HUT) R. Schondorf1, J. Benoit1, M.J. Lafitte2 1 Department of Neurology, Jewish General Hospital, McGill University, Montreal, QC, Canada; 2 DyAnsys, Geneva, Switzerland We have previously described the kinematics of the steady state response to combined HUT and graded heat stress in 13 subjects using a novel time domain method that decomposes beat to beat changes in R-R intervals (RRI) into components that reflect parasympathetic and sympathetic cardiac autonomic activity. Steady state cardiac sympathetic velocity increased incrementally and predictably as orthostatic stress increased (HUT and heat stress) whereas changes in cardiac parasympathetic velocity were less evident. Our method’s ability to track beat-to-beat changes in velocities also allows us to observe the interactions of these two components of cardiac autonomic activity during the transition to and from HUT as orthostatic stress increases. During the onset of HUT at the lowest level of orthostatic stress, the average decrease in RRI reached steady state by 35 s. accompanied by a slow rise in parasympathetic velocity that reached a peak at 28 s. and returned to baseline by 53 s. Sympathetic velocity gradually increased to reach steady state by 37 s. During highest orthostatic stress, the time to steady state RRI (23 sec.) and the rise time in parasympathetic velocity (21 s.) were brisker. The rise in sympathetic velocity reached steady state at 37 s. by which time parasympathetic

303 velocity had declined to baseline. At the termination of HUT in both cases there was a rapid decline in parasympathetic and sympathetic velocities to below baseline negative values that reached a global minimum by 17 s. after termination and returned to baseline by 42 s. The rise in parasympathetic velocity during initial HUT stabilizes the transition to sympathetic predominance during steady state orthostatic stress and is more evident as orthostatic stress increases. We speculate that the negative trajectory during tilt back is indicative of ‘‘recoil’’ within the system as cardiovagal braking is again briefly applied in concert with the rapid transient reduction in sympathetic velocity.

Poster #39 Wavelet transform assessment of heart rate variability during simulated orthostatic stress after antecedent hypoglycemia M. Risk1, I. Bonyhay1, G. Adler2, E. Waring1, V. Curren2, R. Freeman1 1 Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2 Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA Objective: To investigate heart rate (HR) oscillations by time-frequency analysis during lower body negative pressure simulated orthostatic stress (LBNP) after prior exposure to hypoglycemia. Background: Recent evidence suggests that rigorous glucose control may be associated with increased cardiovascular mortality. Previously we found that prior hypoglycemia impairs cardiovagal baroreflex sensitivity and the sympathetic response to hypotensive stress and the simulated orthostatic stress of LBNP. It is not clear if prior hypoglycemia alters HR modulation during LBNP. HR oscillations during LBNP are non-stationary necessitating time-frequency analysis. Methods: Twenty healthy subjects participated in two 3-day admissions, separated by 1–3 months. On day 1 and day 3 of each admission, graded LBNP was used to induce orthostatic stress without the confounding effects of muscle contraction. On day 2, a 2-h hyperinsulinemic [hypoglycemic (50 mg/dL) or euglycemic (90 mg/ dL)] clamp was performed in the morning and repeated in the afternoon. The LBNP was performed on supine subjects sealed at the waist in a metal tank. Following a 5-min baseline period, 4 min of negative pressures of -10, -20, and -30 mmHg were generated. The last 60 s of RR interval time series was used to estimate the low-frequency (LF) and high-frequency (HF) power spectrum using the Daubechies 4 wavelet function. Results: The mean RR and the LF-RR at -30 mmHg LBNP was similar on Day 1 (835 ± 156 vs. 817 ± 183 ms, P = 0.9) (15.0 ± 1.5 vs. 14.6 ± 1.4 log ms2, P = 0.8) whereas on Day 3, RR was longer (778 ± 157 vs. 737 ± 138 ms, P = 0.04) and LF-RR was lower (11.1 ± 1.5 vs. 12.4 ± 1.5 log ms2, P = 0.004) after the hypoglycemic clamp than after the euglycemic clamp. There was no difference in HF-RR on Day 3. Conclusion: The decreased LF power with increased RR during simulated orthostatic stress following hypoglycemia suggests decreased autonomic control of HR and is consistent with the previously observed impaired sympathetic response to orthostatic stress. These changes may contribute to the increased mortality observed in association with rigorous glucose control.

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Poster #40 Peripheral endocannabinoid concentrations during orthostatic stress C. Schroeder1, S. Batkai2, S. Engeli3, J. Tank3, A. Diedrich4, F.C. Luft1, J. Jordan3 1 Medical University Charite´, Experimental Clinical Research Center, Helios Klinikum-Berlin and Max Delbru¨ck Center for Molecular Medicine, Berlin, Germany; 2 Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA; 3 Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany; 4 Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN, USA Introduction: Endocannabinoids, which serve as inhibitory neural feed back system in the brain, lower blood pressure in part through sympathetic inhibition. We hypothesized that endocannbinoids may be released in a similar fashion in the periphery and predispose to neurally-mediated presyncope. Methods: 23 healthy volunteers (11 women, 12 men, aged 29 ± 2 years, body mass index 23 ± 0.6 kg/m2) underwent a graded head-up tilt test. We measured brachial blood pressure, EKG and, finger blood pressure and sampled venous blood in the supine position and at the end of head-up tilt. Anandamide and 1/2-arachidonoylglycerol (1/2-AG) were quantified by liquid chromatography/in-line mass spectrometry. Results: 14 individuals experienced presyncope during head-up tilt. Anandamide concentrations in the supine position were 0.68 ± 0.03 ng/ml and did not change with head-up tilt. 1/2-AG concentrations were 3.0 ± 0.14 ng/ml supine and 3.5 ± 0.23 ng/ml with head-up tilt (P = 0.02). Anandamide and 1/2-AG concentrations were neither related to each other, nor to blood pressure, heart rate, or plasma norepinephrine concentrations. Basal anandamide concentrations were weakly correlated with orthostatic tolerance, defined as the time until the tilt test had to be aborted (r2 = 0.19, P = 0.04). Individuals with anandamide levels above the median had higher heart rate and higher orthostatic tolerance (36 ± 3 min) than those with anandamide levels below the median (25 ± 4 min). Conclusions: In contrast to our expectations, plasma anandamide was directly correlated with orthostatic tolerance, rather than intolerance. Our study may suggest an interaction between endocannabinoids and the autonomic nervous system in human subjects.

Poster #41 Baroreceptor sensitivity and autonomic modulations in obese and non-obese children P. Latchman1, M. Mathur1, M.N. Bartels2, R. De Meersman2 1 Department of Pediatrics, Stamford Hospital, Stamford, CT, USA; 2 Departments of Rehabilitation Medicine and Biobehavioral Sciences, Teachers College, Columbia University, New York, NY, USA Introduction: To understand obesity derived childhood hypertension the study of autonomic modulation is of paramount importance, since autonomic dysfunction is a common denominator in hypertension.

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Clin Auton Res (2009) 19:275–316 Therefore, our aims were to study the effects of childhood obesity on baroreceptor sensitivity (BRS) and autonomic modulation in obese normotensive children. Methods: We compared 14 obese children (OB) to 7 age and gender matched control non-obese children (C) while seated and at rest. ECG and beat-to-beat blood pressure were obtained via the use of a V5 configuration and finger plethysmography. Autonomic modulations and BRS were derived using spectral analysis and transfer function analysis of the electrocardiogram (ECG) and beat-to-beat blood pressures. Statistical analyses: Groups were compared using t-tests with Bonferonni corrections. Probability level was set at P \ 0.01. Results: Preliminary findings revealed that the BRS was significantly reduced in the OB when compared to C [OB = 7.5(2.7) mmHg/s vs. C 16(5.1) mmHg/s P \ 0.01] while seated at rest. No differences in autonomic modulations between the groups were seen at this time; however, trends are present. Discussion: Our preliminary results indicate that baroreceptor sensitivity is significantly reduced in obese children when compared to age-matched controls. In addition, trends are present in several of the autonomic parameters. (Supported by VIDDA foundation).

Poster #42 Impaired sympathetic vasoconstriction in athletes with hypertension O.V. Bogomolova, O.V. Mamontov, A.O. Konradi, E.V. Shlyakhto Federal Centre of Heart, Blood and Endocrinology, Saint-Petersburg, Russian Federation Objective. The study addresses autonomic profile and hemodynamic parameters in athletes with mild arterial hypertension. Design and methods. 27 athletes involved in dynamic sports were included in the study. All athletes were divided into two subgroups – with normal BP levels (group N, n = 13) and with high BP levels (group H, n = 14). The autonomic nervous system (ANS) was tested by cold-pressor test, Valsalva maneuver, spontaneous baroreflex sensitivity, heart rate variability (HRV) at rest and during tilt test. The hemodynamic parameters were assessed by Finometer Pro device (Amsterdam) with beat-to-beat BP registration. Urine metanephine excretion during daytime and nighttime were measured by chromatography. Results. SBR was slightly higher in group H 18.0 ± 6.7 s-1/mmHg versus 13.4 ± 3.3 in groups N (P = 0.08), whereas Valsalva index was similar in both groups. During power spectral analysis of HRV the increase in low-frequency component in group H compared to normotensive one (5,256 ± 1,807 vs. 2,328 ± 942 ms2, P \ 0.05) was demonstrated, but the high-frequency component was similar in both groups. Metanephrine excretion (0.819 ± 0.09 mg/24 h vs. 0.412 ± 0.08 P \ 0.02), cardiac output (6.1 ± 1.2 vs. 5.1 ± 1.0) and stroke volume (108.5 ± 23.3 vs. 89.5 ± 18.2) was significantly higher in hypertensive group, while total peripheral resistance in this group was lower (0.96 ± 0.26 vs. 1.18 ± 0.29 dyn s/cm5 P \ 0.05). Moreover, cold induced vasoconstriction in group H was lower than in normotensive athletes: 0.38 ± 0.20 vs. 0.54 ± 0.1 s.u. (P \ 0.05). Conclusions: Athletes with BP elevation appear impairment of vascular nonspecific sympathetic efferent-mediated vasoconstriction. The observed increase in catecholamine level and cardiac output, sympathetic spectrum of HRV can be related to primary sympathetic overactivity or to secondary compensation of vasomotor function impairment.

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Poster #43 Paradoxically preserved cardiovascular reflexes in patients with continuous flow left ventricular assist devices C. Rasche-Schuermann1, J. Tank1, K. Heusser1, D. Malehsa2, C. Bara2, J. Jordan1, M. Strueber2 1 Institute of Clinical Pharmacology, Hannover Medical School, Germany; 2 Heart-, Thorax-, Vascular-, and Transplantation Surgery, Hannover Medical School, Hannover, Germany Currently, implanted left ventricular assist devices (LVAD) produce continuous flow through rotary pumps such that arterial pulse pressure is profoundly reduced. Considering the importance of pulsatility in afferent baroreceptor signaling, one would expect to observe major abnormalities in cardiovascular autonomic regulation in this almost ‘‘pulseless’’ condition. We performed autonomic function testing including deep breathing, Valsalva maneuver, hand grip test, cold pressor test, and 15
passive head up tilt in two men who had been implanted with LVADs (HeartMate II) for severe heart failure 2‘ years earlier (age 44 and 39 years). We recorded heart rate (HR), systolic brachial pressure (Doppler-ultrasound), stroke volume, cardiac output (impedance cardiography), and finger blood pressure (BP). It was impossible to record muscle sympathetic nerve activity because of electrical noise generated by the LVADs. Respiratory sinus arrhythmia was 1.09 and 1.22. Patient 1 showed a normal HR and BP response during the Valsalva maneuver. Patient 2 had to abort the Valsalva maneuver because dizziness occurred 8 s after forced exhalation with 20 mmHg. Valsalva ratios were 1.16 and 1.19 respectively. During hand grip testing, which had to be discontinued prematurely in both patients due to fatigue, blood pressure increased by 14/12 mmHg and 17/22 mmHg. HR and BP increased during 15
HUT. Stroke volume decreased by 17 and by 27 ml respectively. Spontaneous baroreflex sensitivity determined by cross spectral analysis was 5 ms/mmHg and 6 ms/mmHg. We conclude that cardiovascular reflexes are paradoxically preserved in patients with continuous flow LVAD even though baroreceptors are exposed to much reduced pulse pressure. The observation challenges current textbook knowledge regarding baroreceptor physiology.

Poster #44 Cerebral blood flow regulation during intermittent hypoxia (IH) induced increases in sympathetic activity P.B. Raven, W.L. Eubank, S. Ogoh Department of Integrative Physiology, UNTHSC, Fort Worth, TX, USA A number of chronic diseases such as congestive heart failure, hypertension, obstructive sleep apnea (OSA), peripheral artery disease and obesity are associated with chronic sympathoexcitation and early onset vascular dementia. However, because the established methods of measuring cerebral blood flow (CBF) require steady state conditions, it is generally accepted that increases in sympathetic activity have little or no involvement in CBF regulation. Recently, the use of brief periods (20 to 30 min.) of IH in healthy human subjects have been found to increase muscle sympathetic nerve activity (MSNA) for prolonged periods of time (h). We sought to determine the effect of the IH induced

305 sympathoexcitation on CBF regulation during acute hypotension in healthy adult subjects. Twelve healthy volunteers (7 women and 5 men, ages 32 ± 8 years, body mass index 24 ± 4), volunteered to participate and provide informed consent. The rate of regulation (RoR) was calculated as an index of dynamic cerebral autoregulation (dCA) from the response of the mean arterial blood pressure (delta MAP) and middle cerebral artery blood velocity (delta MCA V) to acute hypotension produced by the bilateral thigh cuff release technique. The RoR during hypotension was significantly attenuated following the IH induction of sympathoexcitation (0.78 ± 0.09 to 0.47 ± 0.07/s; P = 0.003). These data indicate that increased sympathetic activity impaired dCA. We conclude that individuals with hyper-adrenergic diseases will have a compromised dynamic CBF regulation, especially during hypotension.

Poster #45 Alteration of baroreflexes and autoregulation of cerebral blood flow in diabetic autonomic neuropathy S.J. Yeh1, C.C. Chiu2, B.Y. Liau2 1 Department of Neurology, Cheng-Ching General Hospital, Taiwan; 2 Graduate Institute of Electrical and Communications Engineering, Feng Chia University, Taiwan Background and Purpose: Cerebral blood flow (CBF) is steady at mean arterial pressures (MAP) ranging from approximately 50 to 150 mmHg. Earlier studies have shown that the arterial baroreflex (BR) does not influence autoregulation. However, our previous researches showed loss of the phase-shift relationship between MAP and mean CBF in diabetic autonomic neuropathy (DAN) by using cross-correlation function (CCF) to assess cerebral autoregulation (CA). We sought to determine whether blunted BR contributed to the loss of linear dynamics of CA in DAN. Materials and Methods: Thirty-six diabetic patients and ten normal subjects were studied to determine whether alteration of BR in DAN influence CA. Spontaneous baroreflex sensitivity (SBR) calculated by the slope in sequence analysis of beat-to-beat variations in systolic arterial pressure (BP) and R-R intervals obtained from Finapres. Results: In normal subjects, BRS was 9.26 ± 4.6 ms/mmHg, CCF time lead of CA was 1.57 ± 0.85 s and amplitude was 0.57 ± 0.13 in rest supine position. In 23 diabetics with mild AN, when BRS was decreased to 5.99 ± 2.98 ms/mmHg, CCF time lead of CA reduced to 0.87 ± 1.01 s and CCF amplitude to 0.32 ± 0.18. In 13 diabetics with severe AN, BRS was 6.18 ± 3.14 ms/mmHg. CCF time lead was reduced to 0.44 ± 0.93 s and amplitude to 0.25 ± 0.15. Conclusions: Our study showed that there is close linear relationship between BP and HR and between BP and CBF in normal subjects within physiological BP range. Loss of coupling between CBF and MAP is common and is relatively parallel to the severity of blunted BRS in diabetic AN.

Poster #46 Systemic blood pressure, cerebral blood flow and autonomic cardiovascular modulation during mental challenge in SCI J.M. Wecht1,2, D. Rosado-Rivera1, W.A. Bauman1,2 1 Center of Excellence, James J. Peters VA Medical Center, Bronx, NY, USA; 2 Departments of Medicine and Rehabilitation Medicine Mount Sinai School of Medicine, New York, NY, USA

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306 Persons with spinal cord injury (SCI) have partial to complete functional sympathetic cardiovascular denervation, which results in altered cardiovascular response to challenges. However, cerebral autoregulation should maintain adequate and appropriate blood flow to the brain despite fluctuations in systemic cardiovascular and autonomic function. The objective of this preliminary investigation was to document change in systolic blood pressure (SBP), middle cerebral artery blood flow velocity (MFV) and autonomic cardiovascular modulation (HFln, LFln and LFsbp) from supine rest (BL) to a seated mental challenge. Subjects included 18 individuals with chronic SCI (18 ± 10 years): eight with paraplegia (T2–12), 10 with tetraplegia (C4–8) and 10 non-SCI controls. Subject groups were matched for age, height and weight. Supine rest SBP was increased in the paraplegic (131 ± 19 mmHg) compared to the non-SCI (107 ± 15 mmHg; P \ 0.05) and tetraplegic (95 ± 17 mmHg; P \ 0.001) groups and LFsbp was lower in the tetraplegia (3.6 ± 3.6 mmHg2/Hz) compared to the non-SCI (9.7 ± 6.2 mmHg2/Hz; P \ 0.05) group. During the seated mental challenge, SBP, LFln and LFsbp were significantly reduced in the tetraplegic compared to the non-SCI and paraplegic groups. As a possible consequence of reduced SBP and attenuated sympathetic responses to the seated mental challenge MFV was significantly reduced from BL in the tetraplegia group (-17.8 ± 20%; P \ 0.05), which differed significantly from the non-SCI group (6.4 ± 29%; P \ 0.05). Interestingly, although changes in hemodynamic and autonomic function did not differ significantly between the paraplegic and non-SCI groups, MFV was significantly reduced from BL in the paraplegic group (-11.3 ± 9%; P \ 0.05). These data suggest that sympathetic cardiovascular denervation in persons with tetraplegia may result in inadequate cerebral blood flow during mental challenges. Although cardiovascular and autonomic function did not differ among the paraplegic and non-SCI groups, the significant fall in MFV during the seated mental task suggests that another pathophysiologic mechanism may contribute to alterations in cerebral blood flow in persons with paraplegia.

Poster #47 Chronic femoral artery occlusion augments exercise pressor reflex in decerebrated rats H. Tsuchimochi, J.L. McCord, S.G. Hayes, S. Koba, M.P. Kaufman Heart and Vascular Institute, Penn State College of Medicine, Hershey, PA, USA Although the exercise pressor reflex has been shown to be augmented by acute circulatory occlusion, the effect of chronic circulatory occlusion on the reflex remains unclear. We, therefore, determined if ligation of the femoral artery 72 h prior to static contraction augmented the exercise pressor reflex in decerebrated male rats. The pressor responses to static contraction of the hind limb muscles were compared between the side ligated previously for 72 h (chronic occlusion) and the contralateral side, which was either freely perfused or had its femoral artery ligated for 3 min (acute occlusion) before contraction onset. The pressor response to contraction of the side whose femoral artery was ligated 72 h previously averaged 33 ± 6 mmHg whereas the pressor response to contraction of the contralateral freely perfused side averaged 15 ± 4 mmHg (n = 8, P \ 0.05). Likewise the pressor response to contraction on the side whose femoral artery was ligated for 72 h prior to the experiment averaged 31 ± 4 mmHg, whereas the pressor response to contraction on the contralateral side whose femoral artery was ligated for only 3 min averaged 18 ± 4 mmHg (n = 8, P \ 0.05). Surprisingly, the pressor response to contraction

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Clin Auton Res (2009) 19:275–316 of the side whose femoral artery was ligated for 3 min was not significantly different than that observed in the freely perfused leg (n = 8, P = 0.87). Last, the pressor response to contraction in the side whose femoral artery was occluded for 72 h was not changed by TRPV1 receptor blockade with iodo-resiniferatoxin (n = 5) We conclude that chronic femoral arterial occlusion augments exercise pressor reflex.

Poster #48 Microscopic analysis of sympathetic and parasympathetic axon distribution, structure and interaction in whole-mount C57BL/6 mouse atria S.W. Harden, Z.J. Cheng University of Central Florida, Orlando, FL, USA Detailed characterization of autonomic axon distribution, structure, and interaction in normal hearts is essential to study pathological remodeling. However, sympathetic (Sym) and parasympathetic (PSym) innervation and interaction in the heart is not well studied. This study utilized double immunochemical techniques and confocal microscopy to stereologically examine postganglionic Sym tyrosine hydroxylase (TH)- and PSym vesicular acetylcholine transporter (VAChT)-immunoreactive (IR) axons and terminal innervation and interaction in whole-mount atria of C57BL/6 mice (4mo). Atria contained dense networks of TH-, VAChT-, and TH + VAChT-IR axons. Parallel TH- and VAChT-IR axons frequently traveled adjacently and formed individual free terminals in the epicardium and myocardium. Such parallel Sym/PSym axons exhibited large, interdigitized varicosities, suggesting prejunctional interaction. A subset of principal neurons (PNs) in intrinsic cardiac ganglia (ICG) expressed both TH + VAChT-IR and formed free terminals in the myocardium but did not project to other ICG PNs. TH- and VAChT-IR axons heavily innervated atrial vasculature, indicating that both Sym and PSym regulate vascular function. Interdigitized Sym/PSym axons were also observed in the ventricles. This study provides novel insight into Sym and PSym innervation and interaction in the heart and establishes a foundation for future investigations of Sym/PSym cardiac remodeling by cardiovascular diseases.

Poster #49 Response of parasympathetic cardiac vagal neurons to hypoxia and hypercapnia D. Mendelowitz Department of Pharmacology and Physiology, George Washington University, Washington, DC, USA Parasympathetic cardioinhibitory cardiac vagal neurons (CVNs) dominate the control of heart rate. CVNs, which are located in the brainstem, are most active during expiration and are inhibited during inspiration. This cardiorespiratory interaction is largely responsible for respiratory sinus arrhythmia and is mediated by an increase in inhibitory GABAergic and glycinergic neurotransmission to CVNs during inspiration. CVNs do not receive inspiratoryrelated excitatory inputs under normal conditions. However,

Clin Auton Res (2009) 19:275–316 following episodes of hypoxia and hypercapnia (H/H) excitatory neurotransmission to CVNs is recruited to excite CVNs and evoke a bradycardia during H/H. This study examines the neurotransmitters and pathways that are responsible for the excitation of CVNs during and post H/H. This work shows excitatory purinergic and serotonergic pathways are recruited during inspiratory activity. In addition, prenatal nicotine (PNN) exposure is known to dramatically change cardiorespiratory responses and decrease the ability to resuscitate from H/H. In contrast to unexposed animals, in PNN animals H/H recruited excitatory neurotransmission to CVNs during inspiratory-related activity that was blocked by a3b4 nicotinic and glutamatergic receptor blockers. Following H/H, there was a significant increase in inspiratory-related EPSCs that were unaltered by nicotinic or 5-HT3 receptor blockers, but was subsequently inhibited by purinergic and glutamatergic receptor blockers. In control animals, inhibitory mechanisms likely mediate the biphasic changes in heart rate observed during H/H, while excitatory 5HT and purinergic pathways to CVNs likely mediate the resulting bradycardia in recovery from H/H. During H/H, there is an increase in inspiratory-related a3b4-containing nicotinic receptor dependent glutamatergic excitatory neurotransmission to CVNs which likely results in the conversion of the biphasic changes in heart rate seen in control animals to only sustained bradycardia in PNN animals. PNN exposure also decreases serotonergic and enhances glutamatergic neurotransmission to CVNs which may impede the efforts to autoresuscitate in PNN animals challenged with H/H.

307 CB in CHF. A chronic reduction in CB blood flow in CHF may be responsible for these changes due to reduced endothelial shear stress in the CB.

Poster #51 Paraventricular nucleus (PVN) noradrenergicmediated sympathetic activation in chronic heart failure (CHF) K.P. Patel, X. Liu, H. Zheng Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA

Mechanisms of enhanced carotid body function in heart failure: a link to vascular endothelial function

The purpose of this experiment is to examine if the enhanced noradrenergic mechanism in the paraventricular nucleus (PVN) of the hypothalamus contributes to the sympathetic activation in rats with chronic heart failure (CHF). Microinjection of norepinephrine (NE, 1–4 nmol) in the PVN produced a dose dependent increase in renal sympathetic nerve activity (RSNA), mean arterial pressure (MBP) and heart rate (HR). The responses are potentiated in rats with coronary ligation CHF rats versus sham rats (DRSNA, 49 ± 8% vs. 33 ± 3%, P \ 0.05). Furthermore, blockade of adrenergic alpha1D receptors in the PVN with BMY 7378 dihydrochloride (1–4 nmol) demonstrated a greater decrease in RSNA in rats with CHF versus sham (DRSNA, -29 ± 3% vs. -13 ± 3%, P \ 0.05). We also found that mRNA message and protein for alpha1D receptors were significantly increased in rats with CHF compared to sham rats. These data demonstrate that there is a tonic and exaggerated noradrenergic activation of the PVN in rats with CHF. This may play an important role in the increased sympathetic outflow in the CHF condition.

H.D. Schultz, Y. Ding, J. Yin, Y. Li, M. Zimmerman Department of Cellular and Integrative Physiology, University of Nebraska College of Medicine, Omaha, NE, USA

Poster #52

Poster #50

Carotid body (CB) chemoreflex function is enhanced in congestive heart failure (CHF) and contributes to the elevation in sympathetic activity associated with the disease. We have undertaken studies to investigate the physiological and molecular mechanisms responsible for CB sensitization in CHF using a pacing–induced model of CHF in rabbits. CHF (40–50% reduction in ejection fraction) decreased voltage K+ current and increased Ca++ current in CB glomus cells, consistent with the enhanced CB afferent discharge to hypoxia seen in the CHF rabbits. CHF decreased NOS1 and NOS3 protein expression in the CB, with reduced NO activation of K+ channel activity and reduced NO-mediated inhibition of afferent discharge. In addition, CHF inhibited endothelial angiotensin converting enzyme 2 (ACE2) expression in the CB, with reduced Ang 1–7 activation of NOS via the Mas receptor. Conversely endothelial ACE expression was elevated in CHF, increasing angiotensin II mediated superoxide anion levels in the CB to further enhance afferent CB discharge to hypoxia. The role of CB blood flow was assessed in normal rabbits with inflatable occluders to effect a chronic reduction in carotid artery flow. A reduction in carotid arterial blood flow to the extent seen in CHF rabbits (30–40%) evoked changes in expression of NOS and ACE enzymes and enhanced afferent discharge sensitivity of the CB similar to those seen in CHF animals. Endothelial Kruppel-Like Factor 2 (KLF2), a transcription factor activated by shear stress, was markedly reduced in the CB in CHF. Adenoviral transfer of KLF2 gene expression to the CB normalized afferent function in CHF animals. These results indicate that altered NO and Ang II-superoxide signaling in CB glomus cells contribute to the enhanced sensitivity of the

Altered balance of subthreshold K+ and Ca2+ channels contributes to enhanced excitability of preautonomic PVN neurons in hypertensive rats J.E. Stern1, J.A. Filosa1, P.M. Sonner2 1 Department of Physiology, Medical College of Georgia, Augusta, GA, USA; 2 Department of Neuroscience, Cell Biology, Physiology Wright State University Dayton, OH, USA Preautonomic PVN neurons that innervate the rostral ventrolateral medulla (PVN-RVLM) play an important role in the regulation of sympathetic outflow to the cardiovascular system. Importantly, an increased activity in this pathway has been shown to contribute to exacerbated sympathoexcitation during hypertension. Despite this evidence, the precise underlying mechanisms contributing to enhanced activity in this pathway remain unknown. Firing activity in various neuronal types is tightly controlled by a balanced expression/ activity of subthreshold K+ and Ca2+ currents, including IA and IT, respectively. Here, we aimed to determine whether an imbalanced interaction between these currents contributes to enhanced excitability of PVN-RVLM neurons in renovascular hypertensive (RVH) rats. Simultaneous electrophysiological and Ca2+ imaging recordings were obtained from identified PVN-RVLM neurons in hypothalamic brain slices. IA and IT currents shared similar voltage-dependent and kinetic properties. Blockade of IA in control rats lead to an increased

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308 IT peak amplitude (* 96%), enhanced IT-mediated low threshold spike (LTS, * 60%), as well as enhanced LTS-mediated increases in intracellular Ca2 + levels. In RVH rats, IA and IT current densities were decreased and increased, respectively. Moreover, single-cell RTPCR analysis indicated a diminished and increased expression of the KV4.3 and CaV3.1 channel subunit mRNA, respectively. The LTS amplitude and associated increase in intracellular Ca2 + levels were significantly larger in RVH rats (* 25%), while IA modulatory actions were partially blunted. Firing activity of PVN-RVLM neurons was significantly higher in RVH than in control rats. Moreover, the IT channel blocker NiCl2 diminished firing activity of PVN-RVLM neurons in RVH, but not in sham rats. Overall, these data support a dynamic interaction between IA and IT in PVN-RVLM neurons, and that an imbalanced expression and function between these two currents contributes to enhanced neuronal excitability, and likely sympathoexcitation, during renovascular hypertension. Supported by NIH RO1HL68725.

Poster #53 TRPV4 is essential for water’s pressor effect J. McHugh1, M. Appalsamy1, A. Diedrich1,2,3, J. Jordan4, S.R. Raj1,2, D. Robertson1,2,5 1 Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA; 2 Autonomic Dysfunction Center, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; 3 Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; 4 Institute for Clinical Pharmacology, Hannover Medical School, Hannover, Germany; 5 Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA Water ingestion induces a robust pressor response in patients with baroreflex impairment and in mice with sinoaortic deafferentation (SAD) of the baroreflex. The presence of a pressor response following direct intraduodenal infusion indicates that the pharynx, esophagus, and stomach are not critical sites for water’s pressor action. Portal and systemic osmolality were measured 15 min post intraduodenal water infusion and found to be 292.7 ± 1.6 mOsm/ kg and 304.4 ± 2.3 mOsm/kg, respectively (P = 0.002). These data are consistent with the hypothesis that portal osmolality changes might be a potential mediator of the observed response. TRPV4 is an osmo-sensitive channel present throughout the GI region and elsewhere which might have a role in the pressor response of water. We investigated the potential role of TRPV4 on this response in TRPV4-/- mice. Duodenal administration of water in TRPV4-/- mice had a greatly diminished pressor response to water compared to wild type (peak 7.5 ± 0.2 mmHg, P \ 0.002). Recent studies from another group show increased expression of TRPV4 in DRG and mesenteric vessels in animals fed a high salt diet (HS). In our studies, mice on HS tended to show less pressor response to intraduodenally administered water, though not statistically significant (P = 0.06). We conclude that (1) the pressor effect of water is not dependent on pharyngeal, esophageal, nor gastric mechanisms; (2) portal osmolality is reduced following water administration; (3) the TRPV4 channel is essential for water’s effect. Lack of TRPV4 may result in altered absorption of water in the GI, diminished ability to react to the change in portal osmolality following water infusion, or via other mechanisms yet to be discovered; and that (4) animals on HS tended to have less pressor response to water. This may be due to

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Clin Auton Res (2009) 19:275–316 higher initial BP, higher basal TRPV4 activity, and/or other effects of high sodium.

Poster Session III Poster #54 Essential hypotension registry: definition, blood pressure and demographic report L. Medina1,2 Cardiology, Electrophysiology and Neurocardiology Department, Medellin Clinic, Medellin, Colombia; 2 CES University, Medellin, Colombia

1

Objective: To obtain a better understanding of the clinical course of EHO in comparison with normo(N) and hypertensives(HT) and try to find out the physiopathology. Methods: Essential hypotension (EHO) definition: documented [ 20 mmHg (8.5%) or [ 10 mmHg (3%) drop in systolic (S) and/or diastolic (D) blood pressure (BP) within 3 min of standing (drop both 6.5%), and/or SBP \ 90 (8.5%) and/or DBP \ 60 mmHg (3%) (both 10%), a combination of the previous 60.5%; without an identifiable cause or confounding variables; symptoms usually starting \ 20 year-old (asymptomatic included), with out neurological, bladder or sexual dysfunction. This is a registry of consecutive patients consulting a cardiology office, being classified as normo, hyper or hypotensive according to wide accepted criteria. One doctor made the anamnesis and physical examination and typing the data. Blood test, holter monitoring and other diagnostic tools were done in different laboratories. A FileMaker database was designed to store the data. Other information as syncope, coronary artery disease, etc. is fulfilled according to the patient’s condition. Results: 1,703 patients with a mean age of 54 yo (SD 19), 63% female, mean follow-up: 3.47 years (3.7); mean BMI: 24.9 (4.1); mean evaluations/patient: 5 times (7.9); 495 N, 686 HT and 522 EHO (results in this order, W: significant). BP physical examination: Supine SBP (S) W: 117.9; 136.8; 106.1; DBPW: 71.1; 80.4; 64.9; heart rate (HR) [69.4; 72.1 (W vs. N and EHO); 69.5; Immediate standing BP SW: 110.3; 85.1; DW: 70.8; 81.2; 59.4. 24 h ambulatory BP: SW: 118.4; 130.5; 111.1; DW: 71.2; 81.5; 67.8; HR: 75.5; 77.8; 74.2 (W vs. N and vs. HT). In EHO: maximum mean drop in SBP: 25.9 (SD 12.2); DBP: 12.9 (9.1); minimum mean supine SBP: 102.7 (44.7); minimum supine DBP: 62.5 (8). Conclusions: Groups are well classified according to their BP. A mulcentric registry is required.

Poster #55 Syncope diagnosis in patients with no apparent structural heart disease and components for both neurally mediated and cardiac origin (mixed syncope): Is a quantitative history score reliable? L. Medina1, M. Duque1, J. Marin1, E. Gonzalez1, V. Astudillo1, J. Aristizabal1, J. Bernal1, M.A. Restrepo1, A. Arroyave1, Y. Torres2, W. Uribe1 1 Cardiology, Electrophysiology and Neurocardiology Department, Medellin Clinic, Medellin, Colombia; 2 CES University, Medellin, Colombia

Clin Auton Res (2009) 19:275–316 Objective: Syncope causes range from benign (neurally mediated[NM]) to life-threatening (cardiac[C]) conditions. Tilt table testing (TTT) (positive favor NM) have low sensitivity (66%), reason why a quantitative history score (QHS) was developed with 89% sensitivity, 90% specificity (score [ -2 favored NM diagnosis and \-3 C). Methods: Mixed syncope (MxSx) is observed in patients with criteria for both: NM (50.7% orthostatic symptoms, 43.8% younger than 35 yo, 19.2 pre-syncope or syncope with pain or medical procedure, 16.4% sweating or warm feeling before a spell.) and C syncope (documented cardiac cause). These patients represent a special challenge for the QHS because they may have a NM substrate and cardiac mechanisms. Results: 73/771 syncope patients have MxSx, all have electrocardiogram, 50 with QHS and TTT, 36 electrophysiological study, 6 bidimensional echocardiograms and 32 with stress test, 44 holter monitoring, 20 coronariographies, 5 carotid duplex. The C diagnosis was: 48 sinus node dysfunction (SND), 11 supraventricular tachycardia, 5 brady-tachycardia, 3 AV block, 3 ischemic VT, and 1 ARVD, CSH, septal hypertrophy. A positive TT (+TT) confers 0.4 (0.219–0.75) OR; a QHS [ -2 has 5.33 OR (3.34–8.53), QHS \ -3 has 0.1873 (0.117–0.299) OR for MxSx diagnosis. A +TT confers 0.248 (0.083–0.742) OR; QHS [ -2 has an 0.3 (0.15–0.58) OR; a QHS \ -3 has an 3.32 (1.722–6.41) OR for C syncope. A +TT confers 1.89 (1.37–2.607) OR, QHS [ -2 has an 165.99 (116.8–235.8) OR, a QHS \ -3 0.006 (0.0042–0.0086) OR, for NM syncope. Conclusions: TTT and QHS have proven to be very useful to discriminate NM and C syncope. QHS in MxSx (9.4% of syncope population) patients have a misleading results, suggesting NM diagnosis, with risky implications regarding prognosis. A high clinical suspicious for cardiac origin (SND was the main cardiac etiology) and the use of any diagnostic help is mandatory to avoid possible complications.

Poster #56 Clinical spectrum as predictor of tilt induced neurally mediated reflex in patients with orthostatic intolerance J. Freitas, E. Tajera, R. Santos, M.J. Maciel, F. Rocha-Goncalves Centro Estudos Funcao Autonomica, Hospital de Sao Joao, Portugal Objective: Describe the clinical characteristics in patients referred to a tertiary centre with unexplained syncope who developed a neurocardiogenic reflex with symptom reproduction during head-up tilt test. Design: Prospectively, we enrolled 902 consecutive patients during a period of 3 years (1999–2001) with at least two syncope episodes. Interventions: Semi-structured questionnaire was performed with several prodromic and after regaining consciousness symptoms to all patients before head-up tilting. Results: 538 were women (60%). Mean age was 46 ± 20 years. 479 patients had neurocardiogenic response (NCR) to head-up tilt + (53%), 108 sinus carotid hypersensitivity (12%), 11 postural tachycardia response (POTS) to tilting (1.2%), 13 had postural hypotension (1.3%), 10 had hysteric conversion response (1%) and 281 normal head-up tilt test (31%). Female sex had an OR of 1.65 (1.26–2.16) to predict positive NCR to head-up tilt test. Age less than 40 years an OR de 1.032 (1.025–1.039). After age and gender adjustment, prodromal symptoms that had significance were, blurred vision with an OR of 1.48 (1.10–1.96), sudoresis with an OR de 1.42 (1.01–1.99) and palpitations with a negative OR of 0.67 (0.45–0.98). Pallor only had a significant OR when non-adjusted to age and sex. Furthermore, when we looked to the symptoms patients complaint

309 after the event, only when non-adjusted to age and sex we observed a significant OR, fatigue with OR of 1.31 (1.01–1.71), pallor with OR of 1.72 (1.29–2.30) and injury with a negative OR of 0.58 (0.43– 0.79). Conclusions: Clinical spectrum data is important in predicting headup tilt test results in patients with unexplained syncope. Head-up tilt test bust be performed only when patients with syncope had atypical symptoms.

Poster #57 Fainting early or late—does it make a difference? K.J. McNeeley, D. Zhang, T.C. Chelimsky Neurology Institution, University Hospitals Case Medical Center, Cleveland, OH, USA Background: No study has determined whether patients who faint earlier in the course of a tilt table study represent a separate population with a poorer prognosis or different pathophysiology. We analyzed differences across patients with different syncopal times on the tilt-table study to answer this question. Methods: This was a retrospective, IRB approved, chart review. From our database of over 5,000 patients, we identified 1,222 patients with syncope. After excluding patients with orthostatic hypotension, postural tachycardia syndrome and diabetes, we were left with 131 patients with ‘‘pure reflex syncope’’, with an age range of 8 to 73 and 102 females. We divided fainters into an early (\20 min) and late (C20 min) faint times. We compared groups using v2 test, and also regressed tilt duration against continuous variables such as age. Results: By 10 min in the tilt study, only 18% of subjects had fainted, 65% by 20 min, 92% by 30 min and 96% by 35 min. Age was evenly distributed across all syncopal times. Neither the 14 abnormal cardiac responses to deep breathing nor the 20 abnormal Valsalva maneuvers, nor the 28 abnormal axon reflex responses clustered with an early or late faint time. Conclusions: A 10 min tilt will miss 82% of syncopal episodes, while a 30 min tilt increases the yield 10-fold, missing only 8%. Patients with early faint times did not differ from patients with late fainting times with regard to age or autonomic test abnormalities. A prospective study is needed to confirm these observations.

Poster #58 Head-up tilt testing in children and young people with transient loss of consciousness: is it useful? S. Dietz1, J. Murfitt1, L. Florence1, P. Thakker2, W.P. Whitehouse1,3 Section of Human Development, University of Nottingham; 2 General Paediatrics & Paediatric Cardiology; 3 Paediatric Neurology, Nottingham University Hospitals NHS Trust, Nottingham, UK Introduction: Head-up tilt testing (HUTT) is the standard investigation for adults with Transient Loss of Consciousness (TLOC), but it is controversial, especially in children. Therefore, we aimed to assess its usefulness in children by a retrospective clinical audit at our institution. Methods: The medical charts of 100 consecutive patients aged less than 18 years, undergoing HUTT between October 2001 and December 2008 were reviewed. Information about their episodes,

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310 prodromes, triggers, previous tests, indications for the HUTT, the HUTT itself, and clinical outcomes was extracted. Results: Children were 6 to 17 years old (median 14), and 32/100 were males. Symptom onset was at a median age of 12.5 years. The frequency of TLOC ranged from 1 a year to 4 a day (median 1 a week). Some children had one cluster of episodes. In 68/100 trigger were reported, including standing up (20%) and prolonged standing (18%). Dizziness (64%) and altered vision (39%) were the commonest prodromal symptoms. 28/100 had a positive test and 17/100 were negative but symptomatic. 55/100 had a negative asymptomatic test. In 17/28 positive HUTTs, the tilt confirmed the proposed diagnosis (neurally mediated syncope, postural hypotension, or postural tachycardia syndrome). 2/28 were started on medication (fludrocortisone, midodrine). However, in 9/28 neither was the diagnosis clarified nor therapy instigated as a result. Conclusions: Potentially useful information about the TLOC was obtained with reproduction of symptoms in 45/100 cases. The 17/100 with negative but symptomatic results had medically unexplained TLOC: possibly psychogenic or functional or emotional attacks, although without concurrent EEG some uncertainty remains. Therefore, a new protocol with video-EEG-polygraphy and beat-to-beat finger blood pressure recording and more explicit clinical reporting has now been developed.

Poster #59 Cardiovascular autonomic functions in symptomatic and asymptomatic patients of orthostatic hypotension E. Khandelwal, A.K. Jaryal, K.K. Deepak Department of Physiology, All India Institute of Medical Sciences, New Delhi, India Introduction: Patients with orthostatic hypotension are unable to maintain the blood pressure on orthostasis. Despite fall in systolic pressure more than 20 mmHg, only few patients develop symptoms. The study was conducted to quantify cardiovascular autonomic status in the patients of the orthostatic hypotension with or without symptoms to elucidate the contribution of the autonomic deficits in development of orthostatic hypotension and symptoms. Material and methods: The study was conducted in fifteen patients with orthostatic hypotension (7 symptomatic and 8 asymptomatic) and age, sex matched control subjects. The sympathetic reactivity was measured by diastolic blood pressure response to handgrip test and cold pressor test. The parasympathetic reactivity was measured by E:I ratio during deep breathing test, Valsalva ratio during Valsalva maneuver and 30:15 ratio during lying to standing test. 5 min ECG in resting condition was recorded for computation of the heart rate variability in time domain and frequency domain. All the tests were conducted in the morning hours in a quiet room with temperature of 25
C. Results: The patients had lower E:I ratio, Valsalva ratio and diastolic blood pressure response to hand grip test and cold grip test as compared to the controls. The time domain parameter SDNN, pNN50 and SDSD were also lower in the patients. The autonomic deficits were seen in symptomatic as well as asymptomatic patients without any differences in the two groups. The heart rate variability was lower in the asymptomatic group. Conclusion: Patients with orthostatic hypotension have subnormal sympathetic, parasympathetic reactivity and heart rate variability. These deficits are seen in symptomatic as well as asymptomatic and do not relate to occurrence of symptoms.

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Poster #60 Severe cardiodepression underlies prolonged postfaint hypotension W. Wieling1, J. Rozenberg1, I.K. Schon2, D.L. Jardine3, B.E. Westerhof2 1 Department of Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands; 2 BMEYE B.V. Academic Medical Centre, University of Amsterdam, The Netherlands; 3 General Medicine, Christchurch Hospital, Christchurch, New Zealand Background: During tilt-table testing, a low presyncopal blood pressure recovers within 1 min after tilt back to horizontal in the majority of patients. However, in some patients prolonged post faint hypotension (PPFH) is observed. Objectives: We assessed the hemodynamics underlying PPFH after nitroglycerine induced vasovagal presyncope. Methods: 7 patients (2 females, mean age 49, range 32–74 years) experiencing PPFH after tiltback were studied. Presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60
head-up tilt position after a 20 min drug free head-up tilt. Finger blood pressure (BP) was monitored continuously and left ventricular stroke volume was computed from the pressure pulsations (Nexfin). dP/dt was used as a measure of cardiac contractility. The hemodynamics after tilt back were compared with the supine values prior to head up tilt (HUT). PPFH was defined as a systolic finger BP below 90 mmHg for at least 1 min after tilt back. Results: Systolic (SYS) and diastolic (DIAS) BP and heart rate (HR) in the period 1–2 min after tilt back amounted to SYS 74 ± 13 mmHg, DIAS 48 ± 8 mmHg and HR 54 ± 11 bpm compared SYS 124 ± 13 mmHg, DIAS 73 ± 7 mmHg and HR 69 ± 13 bpm during the control period (average of 3 min prior to HUT (P \ 0.05). dP/dt values in the same period were about 35% of the control values. The marked hypotension was mediated by a 40% fall in cardiac output (CO), while systemic vascular resistance was not different from supine control. Head down tilt (30
) or legraising performed in three patients hardly increased CO and SYS BP. 5 min after tilt back to horizontal SYS BP values (98 ± 13 mmHg) were still below supine control (P \ 0.05). Conclusions: PPFH seems to originate from severe cardiac depression.

Poster #61 Hemodynamic study of the efficacy of lower limb and abdominal compression bandage in preventing delayed orthostatic hypotension C. Podoleanu1, R. Maggi2, D. Oddone2, A. Solano2, P. Donateo2, F. Croci2, E. Carasca1, C. Ginghina3, M. Brignole2 1 Cardiology Dept., 4th Medical Clinic, University of Medicine and Pharmacy Targu Mures, Romania; 2 Arrhythmologic Centre, Cardiology Department, Ospedali del Tigullio, Lavagna, Italy; 3 CC Iliescu Heart Institute, University of Medicine and Pharmacy Bucharest, Romania Delayed orthostatic hypotension (DOH) can occur in elderly people after prolonged orthostatic stress. The cerebral hypoperfusion caused

Clin Auton Res (2009) 19:275–316 by hypotension leads to clinical manifestation of Orthostatic Intolerance (OI) that have a strong negative impact on the quality of life of the patients. Aim: to evaluate the hemodynamic response induced by compression bandage applied over the legs, which has been shown to be an effective therapy in avoiding orthostatic systolic blood pressure decrease and in reducing symptoms. Methods: We studied 8 patients affected by DOH, (71 ± 10 years old) with persistent symptoms of OI. These patients underwent a randomised single-blind placebo-controlled tilting study of the hemodynamic effect of elastic bandage applied under standardized pressure over the legs (40–60 mmHg) and over the abdomen (20– 30 mmHg) and the changes in systolic blood pressure (SBP), cardiac output (CO) and total peripheral resistance (TPR) were recorded. Results: In the placebo arm, the SBP decreased from 127 ± 18 mmHg immediately after tilting to 118 ± 20 mmHg after 2 min of placebo leg bandage and to 110 ± 20 mmHg at the end of test minutes despite the addition of placebo abdominal bandage. The corresponding values with active therapy were 130 ± 19 mmHg, 128 ± 18 mmHg (+9±16 mmHg vs. placebo, P = 0.03) and 127 ± 18 mmHg (+16 ± 20 mmHg vs. placebo, P = 0.005) respectively. The corresponding changes in TPR (dyn s m2/cm5) were: 1,722 ± 305 vs. 1,832 ± 475 (P = NS) after tilting, 1,374 ± 213 vs. 1,582 ± 536 (P = NS) at 2 min and 1,132 ± 543 versus 1,600 ± 355 (P \ 0.01) at the end of test. CO showed minimal variations. Conclusion: In elderly patients affected by DOH, lower limb compression bandage was effective in avoiding the DOH and in reducing symptoms by efficiently preventing the orthostatic decrease in SBP by avoiding the fall in TPR

Poster #62 Physiologic assessment of autonomic dysfunction in cough syncope W.P. Cheshire Department of Neurology, Mayo Clinic, Jacksonville, FL, USA Objectives: The mechanism of transient loss of consciousness provoked by vigorous or sustained coughing is incompletely understood and has been attributed to rapidly increasing intrathoracic and transmitted intracranial pressure or to a baroreceptor-initiated neural vasodilator-bradycardia reflex. This study sought to determine whether underlying autonomic dysfunction contributes to recurrent cough syncope. Methods: Clinical histories were reviewed in five cases of recurrent cough syncope identified from 2,014 patients referred for autonomic testing over the previous 5 years. Evaluation in the Autonomic Reflex Laboratory consisted of quantitative sudomotor axon reflex testing, heart rate variability to deep breathing, Valsalva ratio, and beat-tobeat analysis of blood pressure responses to the Valsalva maneuver and tilt. Results: All 5 subjects were men who had smoked a mean of 44 pack years, had consumed moderate to heavy amounts of alcohol, and had evidence of peripheral neuropathy. Four had diabetes or impaired fasting glucose. Cranial imaging in 4 excluded craniocervical junction compromise. Autonomic dysfunction was detected in all cases. The mean decrease in mean arterial pressure during phase II of the Valsalva maneuver was 24 mmHg. Recovery of blood pressure during late phase II or overshoot during phase IV was impaired in all subjects, 3 of whom also had orthostatic hypotension. Cardiovagal responses were impaired in 3. All had distal sudomotor deficits. The mean Composite Autonomic Severity Score was 5.2.

311 Interpretation: Evidence of autonomic dysfunction was detected in all cases of cough syncope studied. The pattern was consistent with an autonomic neuropathy attributable to diabetes or alcoholism. The mechanism of syncope was likely the combined effect of (1) decreased cardiac output due to increased intrathoracic pressure lessening venous return to the heart, and (2) adrenergic failure resulting in incomplete sympathetically mediated recovery of blood pressure following respiratory straining, together causing a transient decrease in global cerebral blood flow.

Poster #63 Systemic capillary leak syndrome: a rare cause of severe episodic hypotension G. Matte, R.W. Shields, Jr. Department of Neurology, Cleveland Clinic, Cleveland, OH, USA Systemic capillary leak syndrome is a rare condition that may superficially resemble dysautonomia. Its recognition is important as specific treatments may prevent death and recurrences. Case report: A previously healthy 41 year old woman presented with severe hypotension without an adequate compensatory tachycardia. She was afebrile and had mild peripheral edema. She was treated for septic shock with poor response to fluid resuscitation and vasopressors. There were no other signs of autonomic dysfunction or neurological impairment. She had 4 previous episodes: 3 within a 4 month period, prior to diagnoses of breast cancer and monoclonal gammopathy (IgG kappa) that were made 10 months prior to this episode, and a fourth episode 1 month after completion of chemotherapy and radiation therapy, 1 month prior to the current episode. Each time, no infectious or cardiac causes were identified and episodes resolved on their own after supportive care. In between the previous episodes, Quantitative sudomotor axonal reflex test disclosed a reduced response at the foot and EMG showed mild peripheral polyneuropathy but cardiovascular autonomic reflex testing and brain MRI were normal. During the current episode, paraneoplastic panel, amino levulinic acid, porphobilinogen, urine organic acid and lumbar puncture did not reveal significant abnormalities. The combination of resistant hypotension, monoclonal gammopathy, hypoalbuminemia and hemoconcentration led to the recognition of systemic capillary leak syndrome. She showed improvement once treated with terbutaline and theophylline. Conclusion: Systemic capillary leak syndrome is a rare lethal condition of yet unclear pathophysiology. It is strongly associated with monoclonal gammopathy. Its ability to mimick acute dysautonomia makes it a differential diagnosis to consider in those situations. Successful treatment with corticosteroids, plasmapheresis, intravenous immunoglobulins, theophylline and terbutaline are reported and may prevent death and recurrences.

Poster #64 Novel immunofluorescent methods in peripheral autonomic nerve fiber imaging C. Gibbons, N. Wang, R. Freeman Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA

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312 Background: Immunohistochemistry is a powerful tool for structural identification of nerve fiber subtypes. Technical obstacles that limit the utility of this method include weak fluorescent signals, high background staining and same-species antibody cross-reactivity. Objective: To develop novel techniques for enhancing the visualization and co-localization of peripheral autonomic nerve fibers. Design/Methods: Three millimeter punch skin biopsies from 40 healthy individuals were obtained after informed consent. Biopsies were fixed in paraformaldehyde-lysine-periodate, frozen and cut into 50 micrometer sections. In order to enable use of same-species antibodies two signal amplification systems, avidin-biotin-fluorochrome (ABC) and tyramide-horseradish peroxidase-fluorochrome (TSA), were used in parallel. Amplification of ABC and TSA in parallel was also used to amplify 2 weak signals simultaneously. For very low antigen levels, the amplification systems were used in series to double amplify 1 very weak signal. Results: The use of TSA and ABC amplification systems in parallel enabled the first successful co-localization of sympathetic adrenergic and sympathetic cholinergic nerve fibers in human cutaneous sweat glands. Primary antibodies from the same species could be amplified individually without cross reactivity or elevated background interference. The confocal fluorescent signal to noise ratio increased and image clarity improved. The use of TSA and ABC systems in series enabled the visualization of very weak signals of sensory neuropeptides within sweat glands. Conclusions: We have successfully imaged cutaneous autonomic nerve fibers using primary antibodies of the same species, improved the florescent signal to noise ratio and performed double amplification of very weak immunoflorescent signals. The signal amplification systems, ABC and TSA, can be combined in parallel or in series to enhance specific image quality. This method has the potential for widespread use in the study of human neural tissues.

Poster #65 Skin biopsy findings in complex regional pain syndrome K.R. Che´mali, L. Zhou Department of Neurology, The Neurological Institute, Cleveland Clinic, Cleveland, OH, USA Complex Regional Pain Syndrome type I (CRPS I) is a chronic asymmetrical autonomic pain condition that is not caused by a large nerve injury. The diagnosis relies mainly on clinical criteria. Laboratory tests are often deceiving. The electrodiagnostic test is generally normal and QSART may show asymmetrically increased or decreased sweat output. We recently reported a case of abnormal skin biopsy of the affected leg with CRPS. In this study, we analyzed the skin biopsy findings in 12 consecutive patients with CRPS I of one or more extremities (16 limbs) and compared these results with skin biopsy of the contralateral unaffected limb. These results were then compared to bilateral skin biopsy of the distal legs in 5 patients with asymmetrical forms of small fiber neuropathy (SFN). 14 out of the 16 affected limbs with CRPS I (87.5%) showed a reduction of the intraepidermal nerve fiber density (IENFD) compared to the contralateral unaffected limb. The amplitude of the reduction varied from 18% to 100% with an average of 44.7%. Sudomotor nerve fiber density (SNFD) appeared reduced in 8 out of 15 limbs (53%) with CRPS I. On the other hand, three out of five patients with asymmetrical SFN showed unilateral reduction of IENFD (60%). The average reduction amplitude was of 41% and varied from no reduction up to 91% reduction. Our findings suggest that the vast majority of patients with CRPS type I display a significant reduction in IENFD and SNFD in the affected limb; therefore, skin biopsy may be a useful

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Clin Auton Res (2009) 19:275–316 laboratory test for the diagnosis of CRPS I. This test, however, may not be specific enough to differentiate between CRPS I and asymmetrical SFN. Larger samples and control groups with other types of limb pain are needed to further characterize the usefulness of skin biopsy in diagnosing CRPS I.

Poster #66 Sudomotor innervation: correlating functional and pathologic data A. Loavenbruck1, W. Kennedy1, G. Wendelshafer-Crabbe1, P. Sandroni2 1 University of Minnesota, Minneapolis, MN, USA; 2 Mayo Clinic, Rochester, MN, USA Objective: To correlate physiologic testing of sudomotor function with immunohistochemical study of sweat glands and their nerve supply. Background: Skin biopsy with immunofluorescent neuronal staining is a sensitive technique for assessment of cutaneous small fibers, and its use clinically continues to proliferate. Studies to date have attempted to correlate physiologic testing of small fiber nerves with epidermal nerve fiber density (ENFD) using skin biopsy. No study has attempted to specifically correlate tests of sudomotor function with histopathologic studies of sweat glands and their nerve supply. Freeman and Gibson recently reported a novel method of quantification of Sweat Gland Nerve Fiber Density (SGNFD) using stereology. The Kennedy Laboratory has developed a novel softwarebased method of measuring SGNFD using exhaustive assessment of all sweat gland tissue in skin biopsies which may ultimately obviate the need for limited sampling. Design/Methods: We enrolled ten subjects, diagnosed with peripheral neuropathy, who had areas of anhidrosis on thermoregulatory sweat test (TST). Subjects underwent thorough evaluation at Mayo Clinic, including complete neurophysiologic and autonomic studies. Skin biopsies were harvested from an anhidrotic area and a normally sweating area as indicated by TST. Biopsies were processed with immunohistochemical staining for nerves and basement membrane. Quantification of SGNFD, total sweat gland volume per total volume of tissue, and ENFD was calculated in each biopsy per the Kennedy Laboratory protocol. Results: In most but not all patients, we found that abnormal sudomotor function as documented by TST was associated either with a decrease in SGNFD, or a decrease in sweat gland volume. Of note, sweat gland volumes were reduced when compared to controls even in areas sweating normally. The results suggest that with further refinement of choice of biopsy sites our method will provide strong correlations between sweat function and nerve structure thus providing a pathological diagnosis of autonomic neuropathy.

Poster #67 Sudomotor dysfunction in autoimmune autonomic ganglionopathy K. Kimpinski1, V. Iodice1, P. Sandroni1, R.D. Fealey1, S. Vernino2, P.A. Low1 1 Department of Neurology, Mayo Clinic, Rochester, MN, USA; 2 Department of Neurology, UT Southwestern Medical Center, Dallas, TX, USA

Clin Auton Res (2009) 19:275–316 Background: Autoimmune Autonomic Ganglionopathy (AAG) is characterized by dysfunction of the sympathetic, parasympathetic, and enteric nervous systems. As a result, sudomotor function is frequently impaired and difficulties with thermoregulation and anhidrosis are common in AAG patients. However, a systemic study of sudomotor dysfunction has yet to be undertaken. Here we characterize the distribution and severity of sudomotor dysfunction in AAG. Methods: A total of 21 patients with ganglionic alpha 3 nAChR antibody positive Autoimmune Autonomic Ganglionopathy were evaluated. Sudomotor function was studied using the thermoregulatory sweat test (TST) and Quantitative Sudomotor Axon Reflex Testing (QSART). Results: Wide spread sudomotor dysfunction was seen in all patients studied. Post ganglionic sudomotor dysfunction was predominant in 17 of 21 patients. This post ganglionic dysfunction showed a positive 3 nAChR antibody levels (post ganglionic, alpha correlation with ganglionic r = 0.637, P = 0.002; mixed ganglionic, r = 0.709, P \ 0.001). Patterns of anhidrosis on TST were consistent with a ganglionopathy in 14 of 21 patients and a distal pattern in 8 of 21 patients. These TST patterns and post ganglionic dysfunction in a proximal to distal pattern (foot [ distal leg [ proximal leg [ forearm) indicate lesions including both the ganglia and distal axon of the post ganglionic sudomotor sympathetic neuron. Conclusions: The pattern of sudomotor dysfunction described is unique to AAG. It is characterized as wide spread, predominantly post ganglionic and a result of lesions at both the ganglia and distal axon. This study supports the hypothesis that this disorder represents a ganglionic neuropathy.

Poster #68 Assessment of other symptoms of autonomic dysfunction in diabetic patients with and without neurogenic orthostatic hypotension J.L. Gilden, A. Nuygen, D. Vahedi, S. Ubhayakar Rosalind Franklin University of Medicine and Science/Chicago Medical School, North Chicago, and Saints Mary and Elizabeth Medical Center, Chicago, IL, USA Background: Autonomic Neuropathy (AN), a chronic complication of patients with Diabetes Mellitus (DM), can result in cardiovascular regulatory abnormalities and orthostatic hypotension (NOH). Patients may also present with abnormal gastrointestinal function, disorders of the bladder and sexual dysfunction, inappropriate sweating, pupillary reflex abnormalities, venous pooling, as well as sleep apnea. Clinical evaluation of symptoms is often difficult and time-consuming in an outpatient setting. Methods: A 21-item screening questionnaire for assessing other symptoms of autonomic dysfunction was administered to 35 patients with clinically significant NOH [(mean age = 52 ± 3 years) (mean decrease in SBP following bedside tilt = -25 ± 2 mmHg with lack of an adequate tachycardic response)(Heart Rate Variability was abnormal, as measured by Expiratory:Inspiratory RR and 30:15 Ratios) [Dx AN = DM (n = 9): Autoimmune (AI) (n = 9): Pure Autonomic Failure (PAF) (n = 8): Other (n = 9)]. MSA and PD patients were excluded. We compared the responses to 125 agematched DM without clinically significant NOH. Results: No significant differences were observed between diabetic and non-diabetic NOH. However, symptoms of dizziness (P \ 0.000), abnormalities in gastrointestinal function (gastroparesis) (P \ 0.002), and inappropriate salivary responses (P \ 0.012), as

313 well as sleep apnea (P \ 0.04), severe tiredness/fatigue (P \ 0.000), venous pooling upon standing (P = 0.05), and abnormal sweating (P \ 0.06) were more likely to be identified by NOH than in DM without NOH. The composite autonomic dysfunction score was also higher (P \ 0.000) in all NOH. Responses to pupillary, sexual, and bladder dysfunction questions did not differ between the groups. In addition, peripheral neuropathic symptoms were more common in NOH. Greater decreases in SBP during bedside tilt were observed in those patients with greater autonomic dysfunction (r2 = 0.4; P \ 0.01). Conclusion: Symptoms of other autonomic nervous system dysfunction, specifically gastrointestinal, salivary, and sweat abnormalities are more common in NOH due to DM, AI, and PAF, than in DM without NOH. This questionnaire can be used as a simple and rapid screen for assessing symptoms of autonomic dysfunction in DM with or without NOH.

Poster #69 Autoimmune autonomic ganglionopathy presenting as Harlequin syndrome W. Singer, R.D. Fealey, P.A. Low Department of Neurology, Mayo Clinic, Rochester, MN, USA ‘‘Harlequin syndrome’’ describes a rare and still poorly understood dysautonomia of heat-, exercise-, and emotion-induced hemifacial flushing and hyperhidrosis. It is thought to result from segmental cutaneous sympathetic denervation resulting in a pale and dry face on the denervated side, and a red and moist face on the other side. Harlequin syndrome has been associated with various etiologies including Pancoast tumor, carotid dissection, and other dysautonomias that can asymmetrically target facial sympathetic innervation, but oftentimes the etiology remains unknown. We describe a case of Harlequin syndrome due to autoimmune autonomic ganglionopathy (AAG). A 43 year-old female reported the gradual onset of exercise-induced hemifacial flushing on the left which slowly progressed in severity over several years and became associated with prominent left hemifacial sweating. More recently she noticed similar symptoms also in the left upper chest. She admitted to loose bowel movements but denied other autonomic symptoms. Neurologic exam was notable only for mildly decreased pinprick sensation in distal lower extremities. Thermoregulatory sweat test revealed markedly asymmetric facial sweating, enhanced on the left and pathologically attenuated on the right, as well as asymmetric distal lower extremity anhidrosis. QSART was normal in the limbs but showed a 5-fold higher sweat volume in the left subclavicular area compared to the right. Cardiovagal function was normal. There was mild impairment of baroreflex-mediated peripheral vasoconstriction. Extensive lab and imaging studies were negative. Ganglionic acetylcholine receptor (AChR) antibodies were positive with a titer of 0.13 nmol/l and a diagnosis of limited AAG was made. In subsequent years, she developed mild orthostatic intolerance and progressive asymmetric sweat loss which could be demonstrated on repeat autonomic testing. She was treated symptomatically and another 2 years later, her autonomic reflex screen was essentially normal and thermoregulatory sweat test was significantly improved. AAG should be part of the differential diagnosis of Harlequin syndrome. It may be the underlying etiology in many previously ‘‘idiopathic’’ cases and testing for ganglionic AChR antibodies should be considered, particularly if no other etiology can be identified.

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Poster #70 Enhancing sensory vibration perception using imperceptible electrical stimulation P.P. Breen1,2, G. O’Laighin1,2, C. McIntosh3, S. Dineen4, J.M. Serrador1,2,5 1 Electrical and Electronic Engineering, National University of Ireland Galway, University Road, Galway, Ireland; 2 National Centre for Biomedical Engineering Science, National University of Ireland Galway, University Road, Galway, Ireland; 3 Department of Podiatry, National University of Ireland Galway, University Road, Galway, Ireland; 4 Department of Medicine, Clinical Science Institute, National University of Ireland Galway, Galway, Ireland; 5 Harvard Medical School, Boston, MA, USA Peripheral sensory loss is a common problem in patients with diabetes. Loss of feeling in the foot can lead to chronic foot problems and amputations. Reversing this sensory loss could greatly improve quality of life and prognosis. A novel paradigm that has been shown to improve sensory perception is the use of stochastic noise applied at the sensory receptor. Our hypothesis was that applying stochastic noise to the conduit nerve, rather than the sensory receptor, would improve neural traffic and vibration perception threshold. Ten healthy subjects (Female = 5, Age 25.4 ± 4.1, Height 176.2 ± 6.9 cm, Weight 71.1 ± 12.6 kg) were tested on both feet. Electrodes were placed proximally to the medial and lateral malleoli such that the tibial nerve was stimulated. We evaluated the vibration perception threshold of the plantar side of the hallux (big toe) using a Neurothesiometer. Stimulation was randomly applied, with two control conditions (no electrical stimulation) and four stimulation conditions (0 ± 15, 0 ± 30, 0 ± 45, 0 ± 60 lA). Optimal stimulation levels for each subject were determined as the level with greatest improved in detection threshold (6 at 15, 7 at 30, 3 at 45, 4 at 30 lA). Stochastic noise significantly improved the ability to detect vibration (control: 6.12 ± 2.03 V vs. optimal stimulation: 5.19 ± 2.07 V, P = 0.002), representing a [ 15% improvement in a group of healthy control subjects with no sensory deficits. These results are the first to demonstrate that peripheral sensation may be improved using imperceptible electrical stimulation applied to a conduit nerve. Future work will be required to evaluate the effectiveness of this technique in patients with neuropathy and its feasibility as a treatment to prevent sensory loss related foot complications.

Poster #71 Posturo-respiratory coupling during upright stance: effects of age and stroke B. Manor1, K. Hu1, C.K. Peng1, L. Lipsitz1,2, V. Novak1 1 Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 2 Institute for Aging Research, Hebrew Senior Life, Boston, MA, USA Postural control is regulated by a complex system that includes visual, proprioceptive, and vestibular input, muscle activity and feedback control. Spontaneous respiration perturbs the body’s center of mass during quiet standing, thereby producing complex non-linear centerof-pressure dynamics. Degradation of the control system, as might occur in aging and neurological diseases, may reduce compensatory

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Clin Auton Res (2009) 19:275–316 control and lead to increased ‘‘posturo-respiratory coupling.’’ We hypothesized that both aging and stroke are associated with increased posturo-respiratory coupling during upright stance. Twenty-five subjects with chronic cerebral infarctions (15 females, aged 51–79 years, height = 1.68 ± 0.10 cm, body mass = 76 ± 14 kg) and 35 agematched controls (22 females, aged 50–80 years, height = 1.67 ± 0.11 cm, body mass = 71 ± 13 kg) stood on a force platform with eyes-open and eyes-closed for 3-min each. Center-of-pressure and respiratory flow volume were simultaneously recorded. The dominant oscillatory mode of respiration and the corresponding oscillatory mode of anterioposterior center-of-pressure dynamics were extracted from each signal using empirical mode decomposition. Instantaneous phase shifts between the two extracted oscillatory signals were calculated over the entire trial using Hilbert transform, and were used to obtain the degree of posturo-respiratory coupling using an entropy-based synchronization analysis. Advancing age correlated with increased posturo-respiratory coupling with eyesopen (R = 0.57, P \ 0.001) and eyes-closed (R = 0.46, P \ 0.001). The degree of posturo-respiratory coupling did not differ between the stroke and control groups when visual feedback was present. Removal of visual feedback increased posturo-respiratory coupling (P \ 0.001); however, an exaggerated increase was observed in the stroke group (50%) compared to controls (17%) (P = 0.03). Evidenced by increased posturo-respiratory coupling, the control system responsible for dissipation of respiratory perturbations is dependent upon vision and degrades with advancing age and stroke. Future studies outlining central/peripheral pathways involved in this control system are warranted.

Poster #72 How common are electrocardiographic, oximeter, and QTc changes in patients during partial complex and secondarily generalized seizures? B.D. Moseley1, E. Wirrell1, E. Benarroch1, J Britton1 Department of Neurology, Mayo Clinic, Rochester, MN, USA Objective: SUDEP is the cause of death in 16.6% of epilepsy patients and is thought to result from seizure-related cardiorespiratory dysfunction. We measured the frequency and risk factors for hypoxemia (oxygen saturation\90%), bradycardia (HR\2nd percentile for age), tachycardia (HR [98th percentile for age), and QTc prolongation in recorded seizures. Methods: 48 patients with partial epilepsy admitted for seizure monitoring between 1 January 2009 and 5 December 2009 were prospectively recruited to undergo pulse oximeter, HR and QTc monitoring during seizures. Pre-, intra- and post-ictal oxygen saturation, HR, and QTc data were evaluated from review of ECG and oximetry records. Seizure characteristics were determined from review of EEG records. Results: Ictal ECG data was available in 57 seizures in 19 patients; pulse oximetry data from 46 seizures in 13 patients. Ictal hypoxemia was recorded in 5/46 seizures and was associated with right onset lateralization (4/18 right, 1/28 left, Chi squared P = 0.047). Ictal bradycardia was recorded in 4/57 seizures but was not correlated with seizure localization. Ictal tachycardia was recorded in 29/57 seizures. Ictal tachycardia was associated with increased mean seizure duration (197 ± 275.8 vs. 51 ± 46 s, Independent-samples T test P = 0.009), right seizure onset (17/26 right, 11/30 left, indeterminate 1/1, Chi squared P = 0.032), and seizure generalization (9/10 generalized, 20/ 47 non-generalized, Chi squared P = 0.006). There was a trend towards post-ictal QTc prolongation, but this was not significant.

Clin Auton Res (2009) 19:275–316 Conclusions: Ictal hypoxia and ictal tachycardia were more common in seizures with right onset lateralization. Ictal tachycardia was also associated with longer duration and seizure generalization. These findings may have implications for the mechanisms and early detection of patients at risk for SUDEP.

Poster #73 Hemispheric sidedness, epilepsy surgery and cardiovascular autonomic functions N. Choudhary1, M. Tripathi2, P.S. Chandra3, R. Sagar4, A.K. Jaryal1, R.M. Pandey5, D. Kondal5, K.K. Deepak1 1 Department of Physiology, AIIMS, New Delhi, India; 2 Department of Neurology, AIIMS, New Delhi, India; 3 Department of Neuro-Surgery, AIIMS, New Delhi, India; 4 Department of Psychiatry, AIIMS, New Delhi, India; 5 Department of Biostatistics, AIIMS, New Delhi, India Purpose: Impairment of autonomic function in temporal lobe epilepsy (TLE) is well known. The effect of TLE surgery on cardiovascular autonomic functions remains inconclusive. It is not known whether sidedness of epilepsy surgery has differential effect on the autonomic functions in patients with temporal lobe epilepsy. Methods: Study was conducted on 17 left-temporal lobe epileptic (LTLE) patients, aged 22.17 ± 10.22 and 28 right-temporal lobe epileptic (RTLE) patients, aged 21.29 ± 12.46 years. Autonomic reactivity and short term heart rate variability (HRV) were assessed before surgery and at 3 and 6 months after the surgery. Results: RTLE patients showed decrement in Valsalva ratio (P = 0.018), DDBP during hand grip test (P = 0.013), increment in, fall in SBP (P = 0.015) during HUT at 6 months after surgery. The LTLE surgery showed decrement in DHR (P = 0.001) and expiration and inspiration ratio (P = 0.002) in deep breathing test while enhancement in DDBP during HGT (P = 0.054) and total power (ms2) (P = 0.016) at 6 months. Conclusion: We observed a differential autonomic response among TLE patients who underwent left or right sided surgery. The cardiovascular sympathetic reactivity was decreased in the RTLE patients and parasympathetic reactivity was decreased in the LTLE at 6 months after the surgery. An improvement of sympathetic reactivity and autonomic tone was seen at 6 months after surgery in LTLE. Our observation supports the lateralization of autonomic functions and suggests that TLE surgery may reduces the risk of sympathetically mediated tachycardia in RTLE patients and parasympathetically mediated bradycardia in LTLE patients.

Poster #74 Brain death is preceded by sympathetic cardiovascular hyperactivity M.J. Hilz1,2, H. Marthol1, T. Intravooth1, P. De Fina3, S. Schwab1 1 Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany; 2 Departments of Neurology, Medicine and Psychiatry, New York University, New York, NY, USA; 3 International Brain Research Foundation, Edison, NJ, USA

315 Background: The period preceding brain death is associated with complex dysregulation. Autonomic dysfunction with altered perfusion may compromise successful organ donation. Objective: To assess autonomic cardiovascular modulation in patients before brain death. Method: In 5 patients (2 women, 63.6 ± 9.6 years) with fatal prognosis due to severe intracerebral hemorrhage (n = 3), ischemic stroke (n = 1), subarachnoid hemorrhage (n = 1), we monitored heart rate as RR-intervals (RRI), beat-to-beat systolic and diastolic blood pressure (BPsys, BPdia), and oxygen saturation (SatO2). Mechanical ventilation kept respiratory frequency constant. We determined spectral powers of RRI in the mainly sympathetic low (LF: 0.04– 0.15 Hz) and parasympathetic high (HF: 0.15–0.5 Hz) frequencies, and powers of systolic BP in the sympathetic LF-range. We calculated the LF/HF-ratio of RRI as parameter of sympathovagal balance. To stabilize organ perfusion, three patients received norepinephrine (0.5– 1.6 mg/h) for up to 72 h before death. During the last 2 h before brain death, norepinephrine was reduced to 0.2–0.5 mg/h. Standard criteria were applied to diagnose brain death. Average values of ten 2-min epochs determined 2–3 h before brain death (first measurement) were compared to average values of ten 2-min epochs assessed 1 h prior to brain death (second measurement) (Wilcoxon test; P \ 0.05). Results: Values of BPsys (127.3 ± 15.9 vs. 159.4 ± 44.8 mmHg), BPdia (60.1 ± 15.6 vs. 74.0 ± 15.2 mmHg), RRI-LF/HF-ratio (1.2 ± 1.6 vs. 3.9 ± 3.9), and BP-LF-powers (2.7 ± 4.8 vs. 23.1 ± 28.3 mmHg2) were higher at the second than the first measurement (P \ 0.05). RRI, RRI-LF-powers, HF-powers of RRI and BP, and SatO2 did not change. Conclusions: The increase in BPs, in sympathetically mediated BP-LFpowers and in the RRI-LF/HF-ratio suggests sympathetic hyperactivity shortly before brain death. Pre-final sympathetic hyperactivity might cause organ damage and thus compromise successful transplantation.

Poster #75 The question remains…is autonomic dysfunction associated with Arnold Chiari malformation? D. Turner West Tennessee Neurology, Bartlett, TN, USA Often described as an incidental finding and benign congenital defect, Chiari malformation may not be readily associated with patient complaints of dizziness, syncope, blurred vision, or brain fog. Are the two related…? For consideration, four case studies are presented involving women with known Chiari malformation and associated syringomyelia. Each subject presents with similar subjective complaints of orthostatic intolerance and hypotension, syncope, profound fatigue, brain fog and ataxia. Exam and ANSAR evaluations are presented including pre and post decompression evaluations as objective representation of subjective relief of symptoms and restoration of function in the two post surgical subjects. The remaining two subjects continue to await and undergo further neurosurgery evaluation. They describe worsening frequency and severity of symptoms and a continued decline in function. This in spite of medical management of symptoms by various specialist managing neurovascular, neuroendocrine and psychologic complaints. Exam and ANSAR evaluations of these subjects are included as well. Are these cases isolated, or rather representative of under recognition of Autonomic Dysfunction due to decreased brain stem, medullary, profusion associated with Arnold Chiari malformation?

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Poster #76 Carvedilol reverses standing parasympathetic excess in non-diabetics R.R. Arora1, R.J. Bulgarelli2, M. Hearyman3, S. Ghosh-Dastidar4, J. Colombo4 1 The Chicago Medical School, Chicago, IL, USA; 2 Cardiology Division, Riddle Memorial Hospital, Media, PA, USA; 3 BK Healthcare, Bald Knob, AR, USA; 4 ANSAR Medical Technologies, Inc., Philadelphia, PA, USA Introduction: Patient can present with beta-blocker and with difficult to control BP, or blood sugars in diabetics, or hormone levels. They also present with fatigue or exercise intolerance, depression, sleep difficulties, gastrointestinal upset, or frequent headache or migraine. The established need for a beta-blocker indicates a previous or continued sympathetic excess (SE). The additional symptoms are associated with parasympathetic excesses (PE) that occur during sympathetic challenges (Valsalva or Stand). Anti-cholinergic therapy to address the additional symptoms is contra-indicated given the need for the beta-blocker. Carvedilol was administered in place of the betablocker to address these additional symptoms. Methods: Serial ANS assessments were administered to 238 patients (145 female, 60.8%; averages: 60.1 ± 12.0 years; 63.3 ± 3.8 inches; 150.4 ± 36.7 pounds) in 12 ambulatory clinics. ANS assessment was performed with ANSAR (Philadelphia, PA) and included 5 min of rest and a quick stand followed by 5 min of quiet standing. HR variability analysis concurrent with respiratory activity analysis was performed to independently and simultaneously compute sympathetic (S) and parasympathetic (P) activity. Results: Patients, on average, were well maintained at rest. They presented with low normal HR, normal BP, normal S, low-normal P, and normal sympathovagal balance (SB). Upon standing they presented with normal S (an increase from rest), but abnormal P (an increase from rest). These patients were switched from their beta-blocker to dose equivalent or lower Carvedilol (6.25 mg bid on average) and retested 4.1 ± 1.1 months later. Their resting responses remained normal, but SB became low-normal indicating extra P as recommended to minimize morbidity and mortality. Their stand responses were normalized. Standing S was reduced, yet remained normal and standing P was corrected. Clinically, patients reported fewer symptoms and associated medications. Conclusion: The two agents included in Carvedilol seems to provide additional benefits for non-diabetics requiring a beta-blocker.

Poster #77 Treatment of multiple system atrophy using intravenous immunoglobulins—update P. Novak1, P. Raven1, B.M. White2, A. Williams2, V. Novak3 1 Department of Neurology, University of Massachusetts, Worcester, MA, USA; 2 Clinical Trials Unit, University of Massachusetts, Worcester, MA, USA; 3 Division of Gerontology, Harvard Medical School, Boston, MA, USA

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Clin Auton Res (2009) 19:275–316 Background: Multiple system atrophy (MSA) is a progressive neurodegenerative disorder associated with parkinsonian, cerebellar and autonomic syndrome. Activation of microglia and production of toxic cytokines suggest that neuroinflammatory mechanisms may play a role in MSA. This clinical trial is based on hypothesis that the neuroinflammatory activity in MSA can be altered using human intravenous immunoglobulins (IVIg). Study design: This is a single interventional arm, single center, openlabel study assessing effects of IVIg in MSA. Interventions include monthly infusions of IVIg, dose 0.4 g/kg, for 6 months. Primary outcome measure is to evaluate safety of the IVIg infusions for treatment of MSA. Secondary outcome measure is to evaluate preliminary efficacy of IVIg for treatment of MSA. We plan to enroll 10 MSA subjects. The following variables are monitored: the unified MSA rating scale (MSARS), quantitative imaging of white matter using 3T MRI and number of inflammatory markers before and after the treatment. Preliminary results: This reports an interim analysis. Eight subjects were enrolled in the study and two subjects completed the study protocol. There were no serious adverse events and subjects tolerated the treatment protocol well. The preliminary data including MSARS’s, white matter changes detected on imaging and responses of inflammatory markers to IVIG will be presented.

Poster #78 A case report of albumin infusions in a patient with pure autonomic failure A. Suleman, R. Horne, M. Ishaque The Heartbeat Clinic, Dallas, TX, USA A 49-year-old female patient with pure autonomic failure (PAF) was referred for further management choices. She has been requiring intermittent IV hydration for approximately 10 years. She had grade IV orthostatic intolerance. She suffered from near-syncope episodes and progressive balance disturbances. Autonomic Reflex panel testing performed in our clinic demonstrated PAF, supine hypertension, and orthostatic hypotension. Marked impairment of postganglionic sympathetic sudomotor and cardiovascular adrenergic pathways compatible with PAF was found. Standard regiment with midodrine, fludrocortisone, Pyridostigmine, salt replacement, IV hydration did not cause much improvement. We conducted tests for blood volume analysis (using Albumin tagged with I 125) and discovered that patient is hypovolemic. Her symptoms were relatively stable for approximately one year when she came back feeling significantly worse with lightheadedness and dizziness. During one of her hospitalizations, trial of IV albumin was given to correct her idiopathic hypovolemia. Tremendous improvement was seen. DDAVP was added, which similarly improved her symptoms. Albumin infusions were initially prescribed to the patient on an as needed basis, but were changed to weekly, and then monthly. Once taken off of them, the patient returned feeling worse, wanting to resume the infusions. Four months later, her symptoms had almost completely disappeared. It is probable that albumin by increasing intravascular volume subsequently helped with her hypovolemia, ultimately increasing blood volume and alleviating her dizziness. Thus, this particular patient with PAF benefited significantly from albumin infusions. This is the first case report of effectiveness of Albumin infusion in PAF patients with hypovolemia.