500

NON1NVAS!I,'E ASSESSMENT OF CEREBROVASCULAR DISEASE

ANNALS OF VASCULAR SURGERY

Commentary

In our vascular laboratory we use two instruments for the noninvasive assessment of extracranial branchiocephalic arterial lesions. One instrument is the Biosound 2000 IIsa, which provides high-resolution real-time scanning and spectrum analysis. The other instrument is the OPG-Gee, which provides information that allows the calculation of bilateral simultaneous ophthalmic systolic pressures and ocular blood flows. We find ibis combination to be exceptionally complementary. The duplex ultrasound interrogation is unsurpassed in assessing the anatomy of the cervical segments of the carotid hemisystems. Ocular pneumoplethysmography is unsurpassed in assessing the physiology of the carotid hemisystems between the origins of the common carotid arteries and the origins of the ophthalmic arteries. The principal limitations of carotid duplex ultrasound interrogation are calcification of plaque, elongation and tortuosity with associated coils, kinks and vessel displacement, high bifurcations, transposition of the internal and external carotid arteries, and extreme technician dependence. Ocular pneumoplethysmography counters these limitations very well. The principal limitations of ocular pneumolglethysmography are the inability to distinguish severe stenoses from total occlusions and the inability to detect lesions which are not of hemodvnamic consequence. Duplex ultrasound interrogati6n counters these limitations most effectively. The OPG-Gee test is always performed first, if possible. The detection of unilateral or bilateral lesions of hemodynamic consequence alerts the technical staff in the performance of the duplex ultrasound interrogation. Asymptomatic and symptomatic thromboses of carotid reconstructions occur in the first several days following operation. Duplex ultrasound interrogation is of very marginal value in this interval. Ocular pneumoplethysm0graphy is a simple rapid test for assessing repair patency during this period [1]. Many investigators have demonstrated that early recurrent stenoses (within three years) have a very low potential for embolization. However, if these recurrent lesions progress to hemodynamic consequence, greater concern is warranted. Our postoperative patients are followed at six month inte~als with serial OPGGee tests, as this is a much more economical survey method. In this area duplex ultrasound interrogation is limited to those patients in whom OPG-Gee tests indicate recurrences of hemodynamic consequence and in those patients who become symptomatic. Over the past 11 ,,'ears (1975 through 19851 our institutional experience with carotid endarterectomy totals 1 242 procedures. By OPG-Gee testing these lesions were as follows :

9 Symptomatic, with hemodynamic consequence a Symptomatic, without hemodynamic consequence o Asymptomatic, with hemodynamic consequence Asymptomatic, without hemodynamic consequence Total

65 % 10 % 20 % 5% 100 %

A recent editorial by Thompson indicates that the latter group does not require operation [2]. If the latter group is eliminated from operative consideration in the future, operations for carotid lesions of hemodynamic consequence will increase from 85 to 89 % of the total. We have documented the improved oculovascular hemodynamics associated with the repair of such lesions in a large series of patients [3]. In a broad review of ocular pneumoptethysmography, we distinghuished the difference between the noninvasive assessment of cerebrovascular hemodynamics and oculovascutar hemodynamics in demonstrating physiologic improvement as a result of the repair of carotid lesions of hemodvnamic consequence [4]. Briefly, cerebral and retinal blood flow are autoregulated, whereas the choroidal blood flow is not. Over 90 % of the ocular blood flow is directed to the choroid. The latter closely reflects the physiology of the carotid hemisystems. Carotid endarterectomy has come under increasing attack, particularly when this procedure is performed upon the asymptomatic patient. The ability to demonstrate physiologic improvement in the asymptomatic patient, if a lesion of hemodynamic consequence is repaired, will be an important issue in the near future. Although duplex ultrasound interrogation would be very effective in documenting patency of the repair, the latter may be insufficient to justify the operation. Postoperative arteriography demonstrated a 96 % patency rate in the EC-IC bypass study, yet this procedure has been pronounced as useless [5]. It is unfortunate that this study included no method of physiologic assessment o[ the patients. There is one circumstance in which the combined application of duplex ultrasound interrogation and ocular pneumoplethysmography remains unique. The vascular surgery group at the St. Antonius Hospital, Utrecht, The Netherlands has insured the safety of proximal common carotid compression by duplex ultrasound interrogation, and they have combined common carotid compression with ocular

~;OLUME 1 NO 4 - 1i)86

VONI.'g~,',45IVE A,~.SES.SMENT OF C't:TREBROVASCUL,4R

pneumoplethysmography in order to ascertain the adequacy of collateral intracranial arterial routes [61. This concept is applicable in situations in which permanent interruption of carotid blood flow is anticipated, such as spontaneous progression of a severe stenosis to total occlusion, carotid ligation, or carotid resection without graft replacement. The Utrecht group has been the principal proponent of what was the original intent of the OPG-Gee [7].

DI.SIE.4SE

50,1

The University of Washington group headed by Strandness has nurtured carotid ultrasound interrogation to a level of magnificent sophistication. In oar vascular laboratory we feel that this technique in combination with ocular pneumoplethysmography is the ideal method of noninvasively assessing the brachiocephalic arterial system. William Gee, MD,

Allentown, Pennsyh'ania

REFERENCES 1. G E E W. L U C K E .IF, M A D D E N AE. Reappraisal of oculm pneumoplethysmograph'; after carotid endarterectomy. J Vase 5,urg 1986 : 4 : 517-21. 2. T H O M P S O N JE. Don't throw out the baby with the bath water : a perspective on carotid endartereetomy. J Vasc Surg 986 : 4 : 543-5. 3. G E E W. P E R L [ N E RK, M A D D E N AE. Physiology of carotid endarterectomy with ocular pneumoplethysmography. J 1last Surg 1986 : 4 : 129-35. 4. G E E W. Ocular pnenmoplethysmography. Surl: Ophthalmol 1995:2'0 : 276-92.

5. The ECilC Bypass Study Group. Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke. N EnglY Med 1985 , 313 : I191-12(~L 6, M O L L Ft,. E I K E L B O O M BC, V E R M E U L E N FEE. VAN LIER HJJ, S C H U L T E BPM. Dynamics of collateral ckeulaticn m progressive asymptoh'natic carotid disease. J Vase Surg 1986 ; 7 : 471)-4 7. G E E W. Ot_LER DW, B R A N N O N WL. Determination of the collateral hemispheric blood pressure (Abstract). Neurolo.gy i975 : 25 : 370.

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FOL TEENTI! ANNUAL SYI OSIUM ON CURRENT CRITICAL PROBLEMS IN VASCULARSURGERY Novemb 13.15, 1987 WN,DORF-ASTORIAHOTEL NEW YORK, NEW YORK PROGRAM "INs year our symposium will again address the current state of the art in vascular surgery and va~ulat radiology. We will also focus on New tlodzons or areas into which vascular surgeons and av~glograph~s may expand their a~iV. i~ie~. Our course, will deal with matcrLal that b e~sential knowledge for the vascular surgeon and radiologist who ~ishes to keep his practice consistent with all that is new and import~nL The lat.e~ significant advance, changing concepts in diagnosis and management, pressing controversies and new techniques, agars and diagnostic modaliti~ are the CRITICAL PROBLEMSAND NEWHOPaZONSIN VASCULARSURGERYthat will be covered in depth, The course will also provide a number of important uFdates and r~valuationS.

FACULTYAND REGISTRANTS More than sixty distinguished surgeons and radiolngi.sts from the United States and Europe ~11 share their insights with an audience of leading surgeons and r~io~is~s in their own right. This combination of rK~"trams and faculty-and the fast paced 15 minute presentations, ~ne~, and workshops- are the key elements which, year after year. mare the SYMPOSIUMuniquely valuable and e.'
SOCIAL EVENTS Special daytime seminars and museum and gallery visits for accompanying members, and evening ~rformances in the t h e a ~ and concert hails for which New YorR is famous, ~11 he ~heduled. A luncheon and r~epticn at the Waldorf Astoda Hotd is aL~oincluded this year.

REGISTRATION Telephone or write to register or for a complete brochure. lhition: $495.00 for pract'.,cing physicians; $395.00 fellows and resident.

For further lnformat~on contact: Office of ConSnulng Medical Education

All rt Einstein College of Nedicine / i ionteliore l edicai Center 3501Bainbddge Argue. Bronx, New Yorl~10467

(2L'2) 920-6674