Management of Aortic Arch Aneurysm Using Profound Hypothermia and Circulatory Arrest

Transcription

1 Management of Aortic Arch Aneurysm Using Profound Hypothermia and Circulatory Arrest Saade Mahfood, M.D., Anjum Qazi, M.D., Jorge Garcia, M.D., Luis Mispireta, M.D., Paul Corso, M.D., and Nicholas Smyth, M.D. ABSTRACT The cases of 9 patients with aneurysms involving the aortic arch, repaired under profound hypothermia (average, 15.5"C) and circulatory arrest, are presented. Five patients underwent elective operation and 4, emergency operation. Arch resection and graft replacement were done in 7 patients. Two patients with infected pseudoaneurysms of the aortic arch received patch grafts. There were 2 deaths (22%) from coagulopathy and decerebration. Seven patients are alive and well 18 to 45 months following repair. The combination of profound hypothermia and circulatory arrest appears to be a promising solution to a difficult problem. Since the successful replacement of aortic arch aneurysms more than fifteen years ago [l], most reports in the literature have described single cases or small series of patients [2]. Even in experienced hands, the rates of mortality and morbidity remain high. Proximal and distal control of the transverse arch requires occlusion of the cardiac outflow and cerebral inflow. Various methods have been employed to preserve cerebral and cardiac function during aneurysm replacement. In the past, these included temporary polyethylene tube shunts [3, 41, temporary and permanent bypass grafts [5-81, and normothermic cardiopulmonary bypass with separate high-flow perfusion of the left carotid and brachiocephalic arteries [l]. Later, lower pressures and flow rates were favored. Separate pump heads with regulated moderate hypothermia were used to decrease the incidence of neurological complications [ Myocardial protection was achieved by separate coronary perfusion, topical hypothermia, and cardioplegia [ 121. To shorten the bypass time, the three arch branches have been reimplanted to the graft in a single anastomosis with an aortic island bearing the three orifices [13]. Tightly woven low-porosity grafts treated by various preclotting autoclaving techniques have been used to decrease the incidence of coagulopathy related to prolonged perfusion and defibrination of blood forced through the graft fabric [14]. Since the early 1970s, the combination of profound hypothermia and circulatory arrest [15, 161 has been successfully utilized for total replacement of the aortic arch. The present report describes our experience in the treatment of aortic arch aneurysm using this method. From the Washington Hospital Center; Washington, DC. Accepted for publication Sept 11, Address reprint requests to Dr. Qazi, 1706 New Hampshire Ave, NW, Washington, DC Material and Methods Between September, 1979, and December, 1981, 9 patients with an aneurysm of the aortic arch and various portions of the a or de aorta were operated on at the Washington Hospital Center. Patients with aortic dissection or lesions of the proximal or distal aortic arch not involving the brachiocephalic or left carotid arteries were excluded from this study. The average age of our patients was 65.8 years, and there were 6 men and 3 women. The cause of the aneurysm was atherosclerosis in 7 patients and mycosis (preexisting trauma), in 2. The aneurysm involved the arch and de aorta in 4 patients; the arch and a aorta in 2; the a aorta, arch, and de aorta in 1; and the transverse arch (pseudoaneurysm) in 2. The diagnosis in each instance was confirmed by aortography. An emergency operation was performed in 4 patients: 3 had sustained cardiopulmonary arrest and 1 was in shock prior to the operation (Table 1). Two of these patients had infected pseudoaneurysms. In Patient l, the aneurysm was acquired following aortic cannulation and triple coronary artery bypass grafting (CABG) performed one and one-half years earlier. The aneurysm repair and erative course were uncomplicated. However, after discharge from the hospital, an aortocutaneous-aortopulmonary fistula developed, requiring two exploratory operations and a right upper lobectomy. Patient 2 was transferred to this hospital in shock. She was found to have a leaking atherosclerotic aneurysm of the a aorta and arch with cardiac tamponade. Patient 3 had an aneurysm of the entire thoracic aorta, and severe hemodynamic and neurological deficits preoperatively. He was the only patient undergoing emergency operation who died. Patient 4 was presumed to have a traumatic pseudoaneurysm aggravated by infection and anticoagulation one week prior to his transfer to our hospital. The remaining 5 patients (see Table 1) underwent elective resection of atherosclerotic aneurysms. One patient (Patient 6) had undergone quadruple CABG 8 days earlier. Operative Technique General endotracheal anesthesia was used for all repairs. A median sternotomy was employed for aneurysms of the a aorta and aortic arch (Fig 1) and for aneurysms involving the a aorta, arch, and de aorta (Fig 2). Aneurysms of the aortic arch and de aorta (Fig 3) or of the aortic arch alone (Fig 4) were approached through a left thoracotomy. 412

2 413 Mahfood et al: Management of Aortic Arch Aneurysm Table 1. Data on 9 Patients Undergoing Repair of Aortic Arch Aneurysm Patient No., Date of Aneurysm Age (yr), Sex Operation Known EMERGENCY OPERATIONS Symptoms Postop. HOS- Resection pita1 Stay Technique Complication (days) Results 1. 53, M 9/79 No Pain, hypertension, CAD (CABG x 3) infection, pulmonary hemorrhage, sternal erosion 2. 76, F 3/ , M 4/81 8 Yr 6 Mo Pain, CAD, hypertension, sudden collapse, cardiac tamponade Pain, CAD, hypertension, sudden collapse, coma 4. 71, M 12/81 No Cough, malaise, fever (pneumonia, PE treated with heparin x 1 wk) pain, L phrenic nerve paralysis, sudden collapse Dacron patch graft (pseudoaneurysm) A aorta and arch A aorta, arch and de aorta; reattach arch vessels Dacron patch graft of pseudoaneurysm; drainage of mediastinal abscess Wound infection, aortocutaneous-aortopulmonary fistula Atrial fibrillation, CHF Bleeding decerebration Hemoptysis, R brachial artery embolism mo mo 2 Died mo ELECTIVE OPERATIONS 5. 71, F 2/81 5 Yr Pain, CAD, hypertension A aorta Pericarditis 9 and arch 6. 54, F 7. 64, M 3/81 3/81 1 Yr 5 Yr Pain, CAD (CABG x 4), hypertension, hoarseness, expanding aneurysm Pain, CAD 8. 69, M 7/ , M 12/81 5 Mo 6 Mo Pain, CAD, hypertension Pain, CAD, CVA, abdominal aortic aneurysm, hypertension, L phrenic nerve paralysis, hoarseness Arch and de- None 15 aorta Arch and de- Coagulopathy 0 aorta Arch and de- None 9 aorta Arch and de- None 16 aorta; ligation of L subclavian artery 28 mo 38 mo Died 28 mo 43 mo CAD = coronary artery disease; CABG = coronary artery bypass grafting; PE = pulmonary embolism; CVA = cerebrovascular accident; CHF = congestive heart failure. Arterial perfusion was through the common femoral artery. The right atrium was cannulated (Sarns twostage 51F) for venous drainage when a median sternotomy was employed, and the femoral vein was cannulated in patients having a left thoracotomy. If venous drainage was considered to be inadequate to maintain calculated flow rates, the main pulmonary artery was drained with a 32F cannula to supplement venous return to the pump. The left ventricle was vented through a cannula placed in the apex. The extracorporeal circuit was primed with 2,000 ml of Plasma-lyte solution and 50 gm of albumin. A bubble oxygenator system was employed with flow rates of 2.4 L/min/m2. A disposable venous-side heat exchanger was used for temperature control. In addition to systemic cooling the myocardium was intermittently bathed with slushed iced saline solution to achieve myocardial protection. Cardioplegic solution

3 414 The Annals of Thoracic Surgery Vol 39 No 5 May 1985 A I Fig 1. (A) Atherosclerotic aneu y sm of a aorta and aortic arch, and (B) its repair (one elective and one emergency operation). B A I ' B Fig 3. (A) Atherosclerotic aneurysm of aortic arch and de aorta, and (B) its repair (four elective operations). A I Fig 2. (A) Atherosclerotic aneurysm of a aorta, arch, and de aorta, and (B) its repair (one emergency operation). A I ' B ' I Fig 4. (A) Infected pseudoaneu ysm of aortic arch, and (B) its repair (two emergency operations). was used in 2 patients. All patients received 1,000 mg of Soh-Medrol (methylprednisolone sodium succinate); 2 patients were given 1,000 mg of Pentothal (thiopental sodium) for added cerebral protection. Sodium nitroprusside was given during the cooling and rewarming process to improve perfusion and reduce core temperature differences. Ventilation with a 3 to 5% mixture of carbon dioxide and oxygen was used during perfusion. Fifty milliequivalents of sodium bicarbonate was given just before circulatory arrest. The average total pump and arrest time was minutes; the average circulatory arrest time, 31.7 minutes; the average cooling time, 33.7 minutes; and the average warming time, 79.9 minutes. Esophageal temperature at arrest was 15.5"C (Table 2). The hematocrit was intermittently monitored and reduced to 20 to 25% to decrease blood viscosity and maintain tissue perfusion at lower temperatures. The major arch branches were left unclamped and were minimally manipulated. To prevent air embolism, the patient was placed in Trendelenburg's position prior to exsanguination. At an esophageal temperature of 18 C or lower, most of the intravascular blood volume was drained into the pump reservoir. The aneurysm was opened longitudinally. The appropriate segment of the arch was replaced with a tightly woven Dacron graft (Cooley low-porosity) (see Fig 1). Anastomoses were performed with continuous 3-0 Prolene sutures. After completion of the distal anastomosis, the de aorta and graft were slowly filled with blood from the arterial cannula. Air was carefully evacuated prior to cross-clamping the graft and restoring cerebral flow. Rewarming was begun while the proximal anastomosis was completed and the clamp was removed. Hemoconcentration was achieved by blood transfusion and diuresis. Protamine sulfate, fresh frozen plasma, and platelets were given to maintain normal clotting and minimize oozing through the graft fabric. The edges of the aneurysmal wall were then snugly sutured around the graft to enhance hemostasis. Cardiopulmonary bypass was discontinued at 36 C. A similar approach was used in Patient 3 (see Fig 2);

4 ~~~ 415 Mahfood et al: Management of Aortic Arch Aneurysm Table 2. Operative Data Total Pump Circulatory Cooling Warming Temperature at Arrest Blood Patient and Arrest Time Arrest Time Time Time (Rectal) (Esophageal) Transfused No. (mi4 (min) (min) ( C) ( C) (mu Average ,000 1,500 1,000 1,250 1,250 1, ,500 1,083.3 however, his entire thoracic aorta was replaced. The distal anastomosis was done first. Then an aortic cuff bearing the arch branches was reattached to the side of the graft in a single anastomosis. The procedure then proceeded as just described. This was the only patient in the series whose graft was preclotted with plasma and autoclaved as described by Cooley and colleagues [12]. In the patients with an aneurysm of the arch and de aorta who had elective repair (see Fig 3), the proximal and distal anastomoses both had to be completed before reperfusion. The left subclavian artery was ligated in Patient 9. A unique approach was used in Patient 1 (see Fig 4). Because of the extent of the aneurysm, a previous median sternotomy, and erosion of the sternum and right upper lobe, median sternotomy was performed after deep hypothermia through femorofemoral bypass was obtained. Results There were 2 deaths. One of the 4 patients undergoing emergency operation died. Patient 3 had a ruptured aneurysm involving the entire thoracic aorta. He sustained cardiac arrest, severe hemodynamic instability, and neurological deficit, and was operated on in a moribund condition. Although the graft was preclotted with plasma and autoclaved and the clotting studies were corrected, the patient had excessive bleeding, never regained consciousness, became decerebrate, and died 2 days following operation. The other death occurred during an elective resection of an atherosclerotic aneurysm of the arch and de aorta (Patient 7). The left lung was firmly adherent to the aneurysm. Following reconstruction, uncontrollable bleeding and pulmonary hemorrhage resulted in the patient s death on the operating table. The average hospital stay was 14.8 days (range, 9 to 22 days). The follow-up period was 18 to 45 months. There were 4 complications. Patient 1 was readmitted for the treatment of an aortocutaneous-aortopulmonary fistula requiring two thoracotomies and right upper lobectomy. He is alive and well 45 months later. Patient 4 required right brachial artery embolectomy and was also readmitted one week after discharge for the evaluation of hemoptysis. An arteriogram and computed axial tomographic scan revealed an intact anastomosis. He is without complaints 18 months later. An episode of atrial fibrillation and congestive heart failure in Patient 2 and pericarditis in Patient 5 prolonged their stay in the intensive care unit by 2 days; otherwise their results were excellent. None of the survivors have any neurological dysfunction. Comment Aortic arch resection and replacement has an average reported mortality rate of 50%. Success depends on careful protection of cerebral tissue, hemostasis, and myocardial preservation. Previous techniques have included bypass with temporary tubes, temporary or permanent grafts, and separate perfusion of the carotid, subclavian [13], and coronary arteries. Underperfusion of the brain results in cerebral ischemia, and overperfusion produces hemorrhage and edema. The risks of air embolism and bleeding from multiple anastomoses and complex cannulas have undoubtedly prolonged the procedure and increased its mortality and morbidity. The use of cardiopulmonary bypass and hypothermia for cerebral and myocardial protection has simplified aortic arch resection. In 1981, Cooley and colleagues [12] presented a large series of 25 patients who underwent aortic arch resection with deep hypothermia and total circulatory arrest (20 patients) or moderate hypothermia with cerebral perfusion (5 patients). The superior vena cava and arch vessels were occluded with snares prior to exsanguination to prevent air embolization to the brain. The grafts were preclotted with platelet-rich plasma and autoclaved, a modification of a technique described a few years earlier [14]. The average circulatory arrest time was 20 minutes. Four of 5 patients requiring replacement of the entire thoracic aorta died. The three major complications re-

5 416 The Annals of Thoracic Surgery Vol 39 No 5 May 1985 sponsible for the unsuccessful outcome in 50% of 20 patients in the series were bleeding, cerebral complications, and myocardial complications. To improve these results, Cooley and co-workers advocated the use of total-body moderate hypothermia with hypothermic cerebral perfusion and circulatory arrest. Separate pump heads and tubes were used to perfuse the brachiocephalic and left common carotid arteries of 5 patients. One patient had a transient neurological complication. All survivors had excellent results, and Cooley and associates recommended moderate hypothermia without cerebral perfusion. This group of researchers [17] updated their experience in In view of the bleeding complications that accounted for most of the 50% mortality in a group of 20 patients operated on with profound hypothermia (14" to 18"C), they advocated moderate hypothermic circulatory arrest at 22" to 24 C. The mean circulatory arrest time was reduced from 22 minutes to 12 minutes. Bleeding complications were not seen, and survivorship was reported at 90%. In 1981, Crawford and Saleh [18] described eight complicated cases treated successfully with total profound hypothermia and modified cerebral circulatory arrest. When a profound level of hypothermia was attained, the head of the table was lowered, the brachiocephalic arteries were clamped, and the rate of perfusion was reduced to 50 to 100 mumin but was never stopped. In 1980, Ergin and Griepp [19] reported the results in 14 patients who underwent total replacement and 1 patient who had partial replacement of the aortic arch with profound hypothermia and circulatory arrest. The operation was performed electively in 10 patients. There was only 1 death, and it was due to coagulopathy and respiratory insufficiency. Three of the other 4 patients operated on urgently (two acute dissections, two ruptures) died. Induction of hypothermia was achieved by body surface cooling followed by core cooling with cardiopulmonary bypass. Ergin and Griepp advocated the administration of 250 mg of methylprednisolone and additional surface cooling of the head, for cerebral protection, with ice bags. To cool the arrested heart, they used a technique involving continuous irrigation with a saline solution inside the left ventricle. In cases of replacement of the a aorta and arch, they cross-clamped the a aorta to perform the proximal anastomosis during core cooling and then completed the distal anastomosis during profound hypothermic circulatory arrest and with the arch arteries clamped. In the series of Ergin and Griepp [19], none of the patients whose time of cerebral ischemia was less than 40 minutes died or had neurological complications. On the other hand, 5 of 8 patients whose period of cerebral ischemia was longer than 40 minutes died or had a stroke. In our series, the only 2 patients who died (Patients 3, 7) had prolonged ischemia (62.7 and 41.3 minutes, respectively). These data, as well as other findings [20], suggest that even at a brain temperature of 10 C, the circulation should not be arrested for longer than 30 minutes, following which intermittent or low perfusion should be instituted for the duration of the operation. We believe that simplification of the technique employed for profound hypothermia and circulatory arrest is essential for success. Our technique differs from others reported in three respects: the arch vessels and aorta are not clamped; care is taken to keep the patient in the Trendelenburg position; and no suction is used at the orifice of the arch vessels. We had no incidence of cerebral air embolism. Only 1 patient (Patient 4) required right brachial artery embolectomy. In addition to core cooling, topical cold saline solution and, in 2 patients, cardioplegia were adequate for myocardial protection. Profound hypothermia was adequate for cerebral preservation. We administered 1,000 mg of methylprednisolone and 1,000 mg of Pentothal (2 patients) for added protection [21,22]. We have not used topical head and neck cooling. The technique of preclotting the graft with plasma and autoclaving was used in 1 patient (Patient 3) who died of coagulopathy and stroke. Tightly woven low-porosity Dacron grafts and blood transfusions to increase viscosity during the rewarming period were satisfactory to prevent bleeding through the graft. The bleeding problem reported by Livesay and associates [17] has not been a frequent complication in our patients. Profound hypothermia gives a margin of safety in cerebral protection that may not be afforded by moderate hypothermia at 22" to 24 C. Livesay and coworkers [17] tried to keep the circulatory arrest time less than 15 minutes at 22" to 24 C. Our experience with profound hypothermia and circulatory arrest for the treatment of aortic arch aneurysm supports our contention that it is the method of choice in managing this entity. References 1. 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, DeBakey ME, Henly WS, Cooley DA, et al: Aneurysms of the aortic arch: factors influencing operative risk. Surg Clin North Am 42:1543, Schafer PW, Hardin CA: The use of temporary polyethylene shunts to permit occlusion, resection and frozen homologous graft replacement of vital vessel segments. Surgery 31:186, Stranaham A, Alley RD, Sewell WH, Kausel HW: Aortic arch resection and grafting for aneurysm employing an external shunt. J Thorac Surg 29:54, Cooley DA, Mahaffey DE, DeBakey ME: Total excision of the aortic arch for aneurysm. Surg Gynecol Obstet 101:667, Creech 0, DeBakey ME, Mahaffey DE: Total resection of the aortic arch. Surgery 40817, Muller WH, Warren DW, Blanton FS: A method for resection of aortic arch aneurysms. Ann Surg 151:225, 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, Crawford ES, Saleh SA, Schuessler JS: Treatment of aneu-

6 417 Mahfood et al: Management of Aortic Arch Aneurysm rysm of the transverse aortic arch. J Thorac Cardiovasc Surg 78:383, Pearce CW, Weichert RF 111, Del Real RE: Aneurysms of the aortic arch: simplified technique for excision and prosthetic replacement. J Thorac Cardiovasc Surg 58:886, Philips PA, Miyamoto AM: Use of hypothermia and cardiopulmonary bypass in resection of aortic arch aneurysms. Ann Thorac Surg 17398, Cooley DA, Ott DA, Frazier OH, Walker WE: Surgical treatment of aneurysms of the transverse aortic arch: experience with 25 patients using hypothermic techniques. Ann Thorac Surg 32:0, Bloodwell RD, Hallman GL, Cooley DA: Total replacement of the aortic arch and the "subclavian steal" phenomenon. Ann Thorac Surg 5:236, Bethea MC, Reemtsma K Graft hemostasis: an alternative to preclotting. Ann Thorac Surg 27374, Nicks R: Aortic arch aneurysm resection and replacement: protection of the nervous system. Thorax 27239, Gschnitzer F: Resektion eines luetischen Aortenbogenaneurysmas im Linksherzbypass mit tiefer Hypothermie und Kreislaufstillstand. Thorax Chirurgie 21:87, Livesay JJ, Cooley DA, Red GJ, et al: Resection of aortic arch aneurysms: a comparison of hypothermic techniques in 60 patients. Ann Thorac Surg 36:19, Crawford ES, Saleh SA: Transverse aortic arch aneurysm: improved results of treatment employing new modifications of aortic reconstruction and hypothermic cerebral circulatory arrest. Ann Surg 194:180, Ergin MA, Griepp RB: Progress in treatment in aneurysms of the aortic arch. World J Surg 4:535, Neville WE: Discussion of Cooley et a1 [12] 21. Hoff JT, Smith AL, Hankinson HL, Nielsen SL: Barbiturate protection from cerebral infarction in primates. Stroke 6:28, Kaufman HH, Reilly EL, Porecha HI', et al: Cerebral ischemia during carotid endarterectomy with severe but reversible changes. Surg Neurol 7:195, 1977