Bypass Grafting and Aneurysmorrhaphy

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1 ORIGINAL ARTICLES Bypass Grafting and Aneurysmorrhaphy for Aortic Arch Aneurysms Harold C. Urschel, Jr., M.D., Maruf A. Razzuk, M.D., and Alan C. Leshnower, M.D. ABSTRACT The technique of permanent aortic arch bypass grafting combined with simultaneous aneurysmorrhaphy, excision or exclusion of the aneurysm without the use of systemic heparinization, cardiopulmonary bypass, or external bypass shunting has been used successfully in treating 5 patients with aneurysms of the aortic arch. There were no complicating cerebral vascular accidents, bleeding diatheses, or signs of distal embolization. There were 2 deaths; 1 patient died early (10 days postoperatively) of myocardial infarction, and the other died over one year later of unrelated causes. Followup has extended to an interval of seven years. The early death subsequent to myocardial infarction in 1 patient prompted the routine use of preoperative carotid and coronary angiography for assessment of these systems. Severe occlusive disease in these vessels requires a staged or simultaneous reconstruction prior to management of the aortic aneurysm. Successful management of aneurysm of the aortic arch remains a monumental technical challenge for the cardiovascular surgeon. This entity has been associated with extremely high mortality and morbidity, primarily as a result of stroke, myocardial infarction, or bleeding. This report reviews our experience with a simplified technique for treatment of aortic arch aneurysms. Our technique utilizes a permanent bypass shunt, along with total arch exclusion and aneurysmorrhaphy, as the primary means of repair instead of using a temporary shunt, as was initially the case. No heparinization, cardiopul- From the Department of Thoracic and Cardiovascular Surgery, Baylor University Medical Center, and the Department of Thoracic and Cardiovascular Surgery, University of Texas Health Science Center, Dallas, TX. Presented at the Twenty-eighth Annual Meeting of the Southem Thoracic Surgical Association, Palm Beach, FL, NOV 5-7, Address reprint requests to Dr. Urschel, Baylor Medical Plaza, 1201 Bamett Tower, 3600 Gaston Ave, Dallas, TX monary bypass, or external temporary shunting is necessary, and controlled hypotension is employed during repair of the aneurysm. Angiography of the carotid and coronary arteries prior to operation is important to determine the safest sequence of operative procedures. Clinical Material and Methods Five patients with aneurysms of the aortic arch underwent operation. Their ages ranged from 54 to 72 years. Initial symptoms included cough, chest pain, wheezing, and hoarseness as a manifestation of left recurrent laryngeal nerve pressure. Angina pectoris was present in 2 patients (Table 1). Atherosclerosis or cystic medial degeneration was the primary cause of the aneurysms. Chest roentgenogram showed a widened mediastinum in each patient. Arteriography delineated the aneurysm; computed axial tomographic scanning with simultaneous radioisotope injection, although not used here, may be helpful in the acute situation if dissecting aneurysm is being considered in the differential diagnosis. All patients after the first underwent separate coronary and cerebral arteriography prior to operation. If severe coronary or cerebral artery disease was demonstrated, coronary artery bypass grafting or carotid endarterectomy was carried out initially or concomitantly as indicated. Technique All 5 patients were operated on without cardiopulmonary bypass or systemic heparinization, thereby avoiding the problems inherent in each of these techniques. General anesthesia was administered using a Robertshaw doublelumen endotracheal tube, which provides selective unilateral ventilation and allows good exposure by collapsing the lung on the side undergoing operation. Arterial and pulmonary artery pressures and arterial blood gases were monitored continuously to ensure the adequacy 579

2 580 The Annals of Thoracic Surgery Vol 35 No 6 June 1983 Table 1. Signs and Symptoms of Aneurysm of the Aortic Arch (N = 5) Sign or Symptom Hoarseness Angina pectoris Enlarged aorta on chest roentgenogram No. of Patients Fig 2. The native ascending aorta supplies the brachiocephalic vessels, and the Dacron bypass graft supplies the descending aorta. Prior to suturing or stapling of the aorta, the aneurysm is opened and the clot removed. Fig 1. A No. 26 woven Dacron graft is sutured, using a partial occluding clamp, to the ascending aorta after lowering the systolic blood pressure iatrogenically to 90 mm Hg. of ventilation. The aneurysm was approached through a left posterolateral thoracotomy extending across the sternum transversely in the fourth intercostal space. The left lung was collapsed, so that ventilation was achieved with only the downside right lung. The bypass graft was inserted before the large aneurysm was approached; this method has obvious safety features, and also precludes difficulty involving any enlarged substernal extension of the aneurysm. A No. 26 low-porosity woven Dacron graft was sutured end-to-side, using a partial occluding clamp, with a continuous 3-0 Prolene suture to the ascending aorta (Fig 1). The clamp was applied to the aorta only after the systemic blood pressure was decreased with an intravenous drip of sodium nitroprusside in a concentration of 50 mg in 500 ml of 5% dextrose in water. The systolic arterial pressure was main- tained at 90 mm Hg. The distal end of the graft was sutured end-to-side in similar fashion to the descending thoracic aorta. Adequate length was allowed to avoid difficulty in managing the aneurysm itself and to avoid later interference with excursion of the lung during inspiration. Following establishment of arterial flow through the bypass graft, the aneurysm was dissected and prepared for aneurysmorrhaphy. A Crafoord clamp was placed obliquely across the aneurysm, from a point just distal to the left subclavian artery and directed medially toward the proximal aspects of the aneurysm at its junction with the normal aorta. Another distal clamp was applied to the aorta, and the aorta was divided through the aneurysm, leaving a cuff of brachiocephalic vessels attached to the ascending aorta. The aneurysm was opened, clots were evacuated, and aneurysmorrhaphy was performed by oversewing, or stapling on both sides, or using both techniques. Prior to placement of the final suture, the Crafoord clamp was released partially to flush out any cellular debris. The cerebral circulation was then served by the native ascending aorta, and the descending thoracic aorta supplied through the plastic bypass graft (Fig 2). As the initial procedure in 1 patient with obstructive coronary artery disease, vein bypass grafts were constructed to the coronary arteries through a median sternotomy. Concomitantly,

3 581 Urschel et al: Aortic Arch Bypass Grafting and Aneurysmorrhaphy A B a woven Dacron graft was sutured to the ascending aorta, rolled on itself, secured with a plastic clip, and left in place. After four weeks, the patient was operated on through a posterolateral thoracotomy approach that did not require dividing the sternum. The graft was unclipped, unraveled, and attached to the descending thoracic aorta after declotting. The aneurysm was transected to perform an aneurysmorrhaphy. No heparin or extracorporeal bypass was necessary. The patient s systolic blood pressure was lowered iatrogenically to 90 mm Hg at the time each clamp was placed. C Fig 3. (A) Postoperative chest roentgenogram in posteroanterior position showing bypass graft. (B) Posterounterior and (C) lateral postoperative thoracic aortograms demonstrating transection, aneurysmorrhaphy, and bypass gruft. Results Two patients have been followed for seven years and the rest for shorter periods; all survivors are asymptomatic. Postoperative angiography determined the validity of the procedure (Fig 3). One patient had a myocardial infarction 10 days following arch resection, even though the aneurysm had been resected successfully. The patient subsequently died secondary to cardiac symptoms. This experience prompted the subsequent use of coronary and cerebral arteriography prior to resection of aneurysms. No other patient had cerebral complications. Another patient died of unrelated causes more than a year following resection (Table 2).

4 582 The Annals of Thoracic Surgery Vol 35 No 6 June 1983 Table 2. Survival and Mortality for Permanent Bypass Grafting and Aneu ysmorrhaphy Variable No. of Pa tien ts Mortality 2 Early (12 days) 1 Late (>1 yr) 1" Survival 3 At 4 yr 1 At 7 yr 2 ~~ "This patient died of causes unrelated to the operative procedure. Comment Arteriosclerotic aneurysm of the aortic arch is a serious condition that ultimately leads to death as a result of rupture in most patients [l]. Resection and replacement of the aortic arch represents one of the most challenging endeavors in cardiovascular surgery. Tuffier [2] ligated the neck of a saccular aneurysm in 1902; his patient died 13 days postoperatively of hemorrhage secondary to necrosis at the ligature site. Cooley and DeBakey [3] and Bahnson [4] reported in 1952 and 1953, respectively, the successful resection of a saccular aneurysm of the arch by lateral aortorrhaphy. In 1954, Mahorner and Spencer [5] described an experimental method for replacing a segment of aorta with the use of partial occlusive clamps that permitted uninterrupted flow through the aorta during graft insertion. Mueller and colleagues [6] reported a method of resection of arch aneurysm in which a permanent bypass graft was sutured end-toside onto the ascending aorta and end-to-end onto the descending aorta, and the brachiocephalic vessels were reconstructed with individual grafts placed end-to-end from the primary graft and end-to-side onto the recipient vessels. The aneurysm of the aortic arch was subsequently resected. In 1957 DeBakey and associates [7] replaced the aortic arch successfully with a homograft, utilizing cardiopulmonary bypass as well as selective brachiocephalic and left carotid perfusion through separate pump heads at high flow rates. Since then, the combination of nomothermic cardiopulmonary bypass, cardioplegia, and separately controlled cerebral perfusion has been the most frequently used form of support. Low flow rates are now utilized instead of high flow rates, a single pump has replaced the separate units, and moderate hypothermia has often been used [8]. Myocardial protection has been effected by separate coronary perfusion or topical hypothermic cardioplegia. Use of cardiopulmonary bypass allows resection of all types of arch aneurysms but is associated with excessive bleeding, which remains a problem following prolonged perfusion [9]. Deep hypothermia offers an alternative with cessation of cerebral perfusion and the preservation of the central nervous system during the period of exclusion of the aortic arch. However, the problem of reperfusion, with attendant emboli and bleeding dyscrasias, had tempered enthusiasm previously [lo]. A modified technique used by Crawford and Saleh [ll] slows but does not entirely stop perfusion, possibly reducing complications. An ever-present obstacle in most medical centers is the paucity of patients available; this limits the experience and prevents the evolution of appropriate, expeditious techniques. The concept of permanent bypass grafting combined with temporary shunting in the management of arch aneurysms was described in 1966 by DeBakey and colleagues [12] and more recently by Crawford and co-workers [9]. Bypass grafting in this setting involves the placement of a temporary shunt sutured end-to-side between the ascending and the descending aorta. The brachiocephalic vessels are perfused with separate grafts arising from the temporary shunt; these grafts are sutured end-to-side to the brachiocephalic vessels. This initial step is followed by resection and then replacement of the aneurysm with permanent grafts sutured end-to-end to the aorta. The brachiocephalic vessels are reconnected to the permanent grafts. Temporary aortic and brachiocephalic shunts are subsequently removed. Because of the advanced age of the patient population, one must take into account (1) the presence of additional arteriosclerotic disease, which requires surgical expediency, and (2) the need to prevent the increased perioperative morbidity associated with the use of shunts, heparin, cardiopulmonary bypass, and hypothermia [13]. As a result, we have identified a

5 583 Urschel et al: Aortic Arch Bypass Grafting and Aneurysmorrhaphy subset of patients with arteriosclerotic aneurysms of the aortic arch in which the technique of permanent graft bypass combined with aneurysmorrhaphy was employed. Our experience with this technique in 5 patients forms the basis of the present report. In this method, the "temporary" bypass remains as a permanent graft. The aneurysm itself is repaired by aneurysmorrhaphy, which aims at preserving the arch vessels without having to interrupt their continuity or flow; thus, making bypass grafts to the brachiocephalic vessels is unnecessary. Vascular reconstruction and repair, namely, the insertion of the bypass graft and aneurysmorrhaphy, are performed under controlled hypotension, which softens the aorta and makes clamp application and repair of the aneurysm easier and safer. With controlled hypotension, strokes or clinical evidence of distal embolization have been avoided because of the gradual tightening of the cross-clamp across the aneurysm at the site of proposed aneurysmorrhaphy, along with venting in the excluded portion of the aneurysm to allow for flushing of atheromatous debris dislodged by the clamping process. Although the experience with this technique for treatment of aneurysms of the arch and thoracic aorta is limited, the concept is surgically expedient. It prevents the complications of intraoperative myocardial infarction and stroke secondary to acute hypertension attendant to cross-clamping or external shunts, and also prevents postoperative hemorrhage from systemic heparinization, prolonged cardiopulmonary bypass, or hypothermia [13]. Bypass grafts from the ascending to abdominal aorta have been used successfully to treat dissecting aneurysms by producing thromboexclusion with blood reversed in the descending aorta [ 141. Because of the frequent coexistence of coronary or cerebral occlusive disease with aneurysmal involvement of the aorta, coronary and carotid arteriography is recommended to ascertain the pathoanatomy of these vessels. Should severe carotid or coronary disease be present, a staged or simultaneous revasculariza- tion of these systems might be indicated prior to repair of the aneurysm [15]. References McNamara JJ, Pressler VM: Natural history of arteriosclerotic thoracic aortic aneurysms. Ann Thorac Surg 26:468, 1978 Tuffier TH: Intervention chirurgicale directe pour un anevrisme de la crosse de I'aorte: ligature du sac. Press Med 10:267, 1902 Cooley DA, DeBakey ME: Surgical considerations of intrathoracic aneurysms of the aorta and great vessels. Ann Surg 135:660, 1952 Bahnson HT Considerations in the excision of aortic aneurysms. Ann Surg 138:377, 1953 Mahorner H, Spencer R: Shunt grafts: a method of replacing segments of the aorta and large vessels without interrupting the circulation. Ann Surg 139:439, 1954 Mueller WH, Warren DW, Blanton FS: A method of resection of aortic arch aneurysms. Ann Surg 15125, 1960 DeBakey ME, Crawford ES, Cooley DA, Morris GC: Successful resection of a fusiform aneurysm of aortic arch with replacement by homograft. Surg Gynecol Obstet 105:657, Crawford ES, Saleh SA, Schuessler GS: Treatment of aneurysms of transverse aortic arch. J Thorac Cardiovasc Surg 78:383, Crawford ES, Fenstermacher GM, Richardson W, Sandiford F: Reappraisal of adjuncts to avoid ischemia in the treatment of thoracic aneurysms. Surgery 67182, Griepp RB, Stinson EB, Hollingsworth JF, Buehler D: Prosthetic replacement of the aortic arch. J Thorac Cardiovasc Surg , 1975 Crawford ES, Saleh SA: Transverse aortic arch aneurysm. Ann Surg 194:180, 1981 DeBakey ME, Beall AC, Cooley DA, et al: Resection and graft replacement of aneurysms involving the transverse arch of the aorta. Surg Clin North Am 46:1057, 1966 Ergin MA, Griepp RB: Progress in treatment of aneurysms of the aortic arch. World J Surg 4:535, 1980 Carpentier A, Deloche A, Fabiani JN, et al: New surgical approach to aortic dissection: flow reversal and thromboexclusion. J Thorac Cardiovasc Surg 81:659, 1981 Urschel HC, Razzuk MA, Gardner MA: Management of concomitant occlusive disease of the carotid and coronary arteries. J Thorac Cardiovasc Surg 72:829, 1976