Surg Today (2000) 30:754–758

Surgical Treatment for Graft Stenosis After Repair of an Interrupted Aortic Arch: Report of Two Cases Tomokazu Kosuga, Shuji Fukunaga, Koji Akasu, Shingo Chihara, Shogo Yokose, Hidetoshi Akashi, Takemi Kawara, Ken-ichi Kosuga, and Shigeaki Aoyagi Department of Surgery, Kurume University School of Medicine, 67 Asahimachi, Kurume 830-0011, Japan

Abstract We report herein two cases of patients who underwent successful reoperation for graft stenosis after repair of an interrupted aortic arch (IAA). The first patient was a 10-year-old girl who suffered from upper limb hypertension 9 years after her initial operation. Cardiac catheterization revealed a pressure gradient of 55 mmHg across the repaired arch. At reoperation, a left subclavian turndown anastomosis was performed, following which the hypertension resolved and a cardiac catheterization done 5 years later demonstrated sufficient growth of the restored arch with no significant gradient. The second patient was a 17-year-old boy who suffered from general fatigue and intermittent hypertension 12 years after his initial operation. Cardiac catheterization revealed a gradient of 60 mmHg across the repaired arch. He underwent an extraanatomic ascending to descending aortic bypass employing an additional 18-mm graft, and a postoperative cardiac catheterization showed no gradient between the ascending and descending aorta. Our experience has shown that IAA should be repaired without prosthetic grafts if possible. Although extraanatomic bypass is useful for reducing the operative risks at reoperation, a large graft should be used to avoid the need for a third operation. For young children expected to outgrow a second graft, performing an endogenous anastomosis, such as a left subclavian turndown anastomosis, should be considered as an alternative. Key Words Interrupted aortic arch · Graft stenosis · Reoperation · Left subclavian turndown anastomosis · Extraanatomic aortic bypass

Reprint requests to: T. Kosuga Received: June 14, 1999 / Accepted: March 24, 2000

Introduction Although the surgical results of interrupted aortic arch (IAA) have improved in the last decade,1–3 during midto long-term follow-up, restenosis is a common complication requiring reintervention, whether or not a prosthetic graft is used for arch repair. A number of earlier reports have stated that repair using a prosthetic graft was superior to direct anastomosis due to the low incidence of restenosis occurring within a few years.4–6 However, as more cases of this rare anomaly have been experienced in recent years, direct anastomosis has been found to contribute to excellent results with a lower incidence of early stenosis.3,7 In our hospital, direct anastomosis and left subclavian or left carotid turndown anastomosis are the preferred methods of surgical treatment, although grafts have been used in some cases to prevent tension on the anastomosis; however, when a graft is used, the development of growth-related stenosis after few years is unavoidable. While the goal of surgical treatment for graft stenosis is to correct the pressure gradient across a graft, optimal techniques should be employed to prevent complications, especially recurrent stenosis requiring a third operation. We describe herein the cases of two patients who underwent reoperation for graft stenosis by two different techniques after IAA repair with a prosthetic graft.

Case Reports Case 1 A 16-month-old female infant with heart failure was referred to our hospital where a diagnosis of type-A IAA, patent ductus arteriosus, and a coexisting ventricular septal defect was confirmed. She underwent a one-stage complete repair through a median sternotomy under cardiopulmonary bypass, at which time a

T. Kosuga et al.: Graft Stenosis After Aortic Arch Repair

10-mm Teflon graft was inserted between the ascending and descending aorta with minimized dissection around the site of interruption, and the ductus arteriosus was ligated. The ventricular septal defect was closed with a Teflon patch at the same time. This was the first successful operation for IAA to be performed at our hospital.8 Follow-up cardiac catheterizations done 2 and 4 years postoperatively showed no pressure gradient across the graft. At the age of 10 years, the patient was found to have developed hypertension in the arms without any remarkable symptoms. Cardiac catheterization demonstrated that the ascending and descending aorta had outgrown the graft, which was patent, and that the gradient had increased to 55 mmHg (Fig. 1). A reoperation was performed through the original median sternotomy wound. The 10-mm Teflon graft, in which some degree of thrombus had developed just proximal to the distal anastomosis, was relatively narrow compared with the ascending and descending aorta, which were 16 and 13 mm in diameter, respectively. Using the left subclavian artery, which was 5 mm in diameter, to reconstruct the arch appeared to be more appropriate for this patient than an aortic bypass with a second graft. Therefore, the left subclavian artery was exposed and divided, taking care not to injure the left vagus nerve. The proximal segment of the left subclavian artery was turned down and anastomosed to the descending aorta (Fig. 2a). The patient had an uneventful postoperative course without any complications associated with ligation of the left subclavian artery. Her upper limb hypertension resolved after the reoperation without any medication (Fig. 1). Follow-up cardiac catheterization done when she was 15 years of age showed no significant gradient across the new aortic arch composed of the patent graft and the proximal

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segment of the left subclavian artery, which had grown to approximately 8 mm in diameter (Fig. 2b). No evident gradient between the upper and lower limbs was found 9 years after the reoperation (Fig. 1). At 19 years of age, she gave birth to a healthy infant without any complications. Case 2 A 4-year-old boy was admitted to another hospital with right hemiparalysis, where cerebral angiography and

Fig. 1. Follow-up data in case 1. BP, upper limb blood pressure (open triangles); PG (a–d Ao), pressure gradient between the ascending and descending aorta revealed by cardiac catheterization (solid circles); PG (u–l L), pressure gradient between the upper and lower limbs (solid diamonds)

b

Fig. 2. a Schema of the reoperation in case 1. b Aortography 10 years after the reoperation. The proximal segment of the left subclavian artery had grown to approximately 8 mm in diameter. AAo, ascending aorta; DAo, descending aorta; G, 10-mm graft inserted at the initial operation; LSA, proximal segment of the left subclavian artery; D, diameter of the LSA

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computed tomography revealed the cause to be cerebral infarction resulting from Moyamoya disease. Physical findings showed a systolic ejection murmur, and a blood pressure of 160/85 mmHg in the right arm and 128/70 mmHg in the left arm. The pulses of the bilateral femoral arteries were significantly weak. Echocardiography indicated no intracardiac anomaly. He underwent encephalo-duro-arterio-synangiosis for the Moyamoya disease, and was subsequently referred to our hospital at 5 years of age. Cardiac catheterization indicated type-B IAA. It also showed that the ductus arteriosus was not patent and that there was significant development of the collateral vessels supplying blood to the lower body; however, no coexisting intracardiac anomaly was found. A left thoracotomy and median sternotomy confirmed aortic arch discontinuity between the left carotid and left subclavian arteries and extended length between the ends of the aorta. The aortic segment between the innominate and left carotid artery was narrow, and some aneurysm-like lesions were recognized in the left subclavian artery and descending aorta. Therefore, a 10-mm Dacron graft was positioned between the aortic arch in the base of the left carotid artery and the descending aorta. After the operation, a greater gradient across the graft developed as the patient grew. Follow-up cardiac catheterization showed a gradient of 30 mmHg 2 years postoperatively, and a gradient of 40 mmHg 7 years postoperatively (Fig. 3). When the patient was 17 years of age, he had begun to suffer from general fatigue and intermittent hypertension. The pressure gradient across the graft was revealed to be 60 mmHg by cardiac catheterization, and

a

T. Kosuga et al.: Graft Stenosis After Aortic Arch Repair

echocardiography indicated mild left ventricular hypertrophy. He underwent a reoperation in which an extraanatomic ascending to descending aortic bypass with an 18mm Dacron graft was performed through the previous median sternotomy wound (Fig. 4a). Under cardiopulmonary bypass, achieved by inserting an arterial cannula into the ascending aorta and by single venous cannulation of the right atrium, the heart was retracted

Fig. 3. Follow-up data in case 2. BP, upper limb blood pressure (open triangles); PG (a–d Ao), pressure gradient between the ascending and descending aorta revealed by cardiac catheterization (solid circles)

b

Fig. 4. a Schema of reoperation in case 2. b Aortography 3 months after the reoperation. AAo, ascending aorta; DAo, descending aorta; G1, 10-mm graft inserted at the initial operation; G2, 18-mm graft inserted for the extra-anatomic aortic bypass between the AAo and DAo at the reoperation

T. Kosuga et al.: Graft Stenosis After Aortic Arch Repair

and the posterior pericardium was opened to expose the thoracic descending aorta. The distal end of the graft was anastomosed to the thoracic descending aorta with a side-biting clamp. It was possible to complete the proximal anastomosis to the ascending aorta before releasing the aortic cross-clamp because an adequate length of proximal ascending aorta could be obtained without releasing it. The patient had an uneventful postoperative course, and a cardiac catheterization done 3 months after the reoperation indicated no gradient between the ascending and descending aorta (Figs. 3 and 4b).

Discussion Patients who have undergone IAA repair must be followed up carefully for signs of restenosis which may be indicated by a systolic murmur or hypertension in the arms. Interestingly, the blood pressure of our case 2 was usually within normal limits and only became high intermittently, the systolic pressure reaching 180 mmHg, which was partly attributed to the developed collateral vessels and his decreased activity in day life. Thus, restenosis does not always induce upper limb hypertension at rest and although these two patients did not undergo an exercise test, this is considered useful for contributing to the early detection of restenosis even in asymptomatic patients. A gradient over 30–40 mmHg by cardiac catheterization or persistent hypertension causing left ventricular strain requires reintervention although a diagnosis of restenosis, and the indications for reoperation are inconsistent. Aeba and associates reported that the indications for reoperation include a pressure gradient of at least 20 mmHg, a narrowing anastomotic site greater than or equal to 50% of the neighboring aortic diameter, or exercise-induced arm hypertension with a systolic pressure of at least 200 mmHg.9 The surgical correction of graft stenosis can be achieved by various techniques.10–15 One serious problem at reoperation involves ensuring effective cerebral protection in infants or children during reconstruction of the aortic arch, and another involves deciding whether to dissect around the previously inserted graft where severe adhesions may have developed. While the best procedure may be direct anastomosis with removal of the previous graft whenever possible, this may require cerebral protection such as circulatory arrest under deep hypothermia. Moreover, it is likely to be difficult to achieve without subjecting the anastomosis to tension in most instances. In this situation, aortic bypass with a second graft has the benefit of being a relatively short and noninvasive operation, and may help to prevent some complications such as bleeding

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due to lysing dense adhesions, damage to the friable aortic wall and important collaterals, or injury to the vagus and recurrent laryngeal nerves. Unless aortic bypass grafting in children is carried out employing a large graft with a diameter of at least 16 mm, restenosis can occur as they grow.16 Moreover, extraanatomic aortic bypass as performed in case 2 may reduce blood flow in the bypassed aortic segment in children, and this can cause its inadequate growth.16 In this situation, if a third operation was required, a further aortic bypass with a larger graft would be difficult. For small children in whom the insertion of large grafts is impossible or for young children expected to outgrow a second graft, performing an endogenous anastomosis using an arch vessel should be considered if it is an appropriate size. The repaired aortic arch will increase in size sufficiently as the patient grows. In case 1, the turndown anastomosis using the left subclavian artery which was 5 mm in diameter appeared to correct the restenosis because the 10-mm graft was patent. Therefore, we chose this method due to its growth potential for arch reconstruction, rather than aortic bypass with a second graft, and no significant gradient resulted as she grew. Furthermore, this method is amenable to balloon angioplasty if necessary. When a child undergoing a second operation is old enough, it is preferable to perform aortic bypass with a second graft. Extraanatomic bypass should be noninvasive and carried out using a large graft as previously described. In case 2, the ascending to descending aortic bypass using an 18-mm graft was able to be accomplished only through a median sternotomy, and the patient suffered no postoperative complications, leaving our hospital after a short admission. In summary, IAA should be repaired without prosthetic grafts if possible because the insertion of prosthetic grafts unavoidably necessitates subsequent surgical treatment after a few years. Although extraanatomic aortic bypass is useful for reducing the risks at reoperation, it should be performed with as large a graft as possible to avoid the need for a third operation when further aortic bypass grafting is anticipated to be more difficult. For young children, performing an endogenous anastomosis using an arch vessel without the use of a graft should be considered as an alternative.

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