Operation for Type A Aortic Dissection: Introduction of Retrograde Cerebral Perfusion

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1 Operation for Type A Aortic Dissection: Introduction of Retrograde Cerebral Perfusion Masaya Kitamura, MD, Akimasa Hashimoto, MD, Takehide Akimoto, MD, Osamu Tagusari, MD, Shigeyuki Aorni, MD, and Hitoshi Koyanagi, MD Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College, Tokyo, Japan Circulatory support during operation for type A aortic dissection is controversial among many medical centers. In the last 21 years, 100 patients with type A aortic dissection underwent 102 operations including 2 reoperations, and 29 patients showed Marfan's syndrome. During operation, no cerebral perfusion technique was used through February 1985 (period I), antegrade cerebral perfusion was applied since March 1985 (period II), and retrograde cerebral perfusion was introduced in November 1990 (period III). Surgical results were compared among these subgroups. Operative mortality was 12.1% in 33 chronic and 57.1% in 7 acute patients in period I, 11.1% in 27 chronic and 54.5% in 11 acute patients in period II, and 6.7% in 15 chronic and 0% in 9 acute patients in period III (period II versus III; p = 0.04). Retrograde cerebral perfusion decreased permanent brain complications. The 5-year actuarial survival was 59.7% in period I and 63.2% in period II (not significant), and the 3-year survival of period III was 91.7%. Actuarial survival of period III was significantly higher than those of periods I and II (p < 0.05). Surgical repair of aortic arch with cerebral perfusion techniques reduced the residual aneurysms. These results show that surgical results of type A aortic dissection in this series improved with the introduction of retrograde cerebral perfusion and extended surgical procedures. (Ann Thorac Surg 1995;59:1195-9) A ortic dissection still remains one of the major lifethreatening diseases, and its incidence is increasing in recent years. Surgical strategies for aortic dissection have been developed in the last decade [1-4]. However, circulatory support techniques during aortic operations, especially for Stanford type A dissection, are different and controversial among many medical centers in the world [5-9]. We have performed surgical treatment of type A aortic dissection for more than 20 years [10-12]. The purpose of this investigation is to evaluate the change in surgical results of type A aortic dissection with the introduction of retrograde cerebral perfusion. Material and Methods From May 1972 to June 1993, 100 consecutive patients with Stanford type A aortic dissection were treated surgically at the Heart Institute of Japan, Tokyo Women's Medical College. Sixty-seven patients were men and 33 were women. The age of patients ranged from 20 to 73 years and averaged 48.8 _ years. Two of those patients received two reoperations; therefore, we had 102 surgical cases in this time period. In this investigation, the type of aortic dissection was classified according to the Stanford criteria [13, 14], and 102 cases were selected as Stanford type A aortic dissection involving the ascending aorta. With respect to the Accepted for publication Feb 6, Address reprint requests to Dr Kitamura, Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162, Japan. timing of operation, aortic dissection was defined as acute in patients who had received surgical treatment within 14 days after the onset of symptoms. Twentyseven patients had acute type A dissection and 75 had chronic type A. Of 100 patients, 29 patients (29.0%) had Marfan's syndrome [15]. All patients gave informed consent, and the institutional committee on human research approved the present study protocol. Intraoperative Circulatory Support Concerning circulatory support during operation on aortic dissection, several types of assisted circulation have been used over the last 20 years [10, 11]. In patients with type A dissection, total cardiopulmonary bypass with simple aortic cross-clamp was performed in the initial years, and cardioplegia was introduced in 1977 [16]. In type A patients with an arch tear, temporary bypass between arch branches or hypothermic circulatory arrest was used by February 1985, antegrade selective cerebral perfusion [10] (Fig 1) was applied since March 1985, and retrograde cerebral perfusion [17] (Fig 2) was introduced in November In practical management of the antegrade selective cerebral perfusion, a total blood flow rate of 8 to 10 ml-kg -l-rain -~ was maintained by two small roller pumps after the induction of deep hypothermia, and blood pressure in the bilateral superficial temporal arteries was controlled at 40 to 60 mrn Hg on the average. Retrograde selective cerebral perfusion with deep hypothermia was carried out at approximately 300 ml/min through a cannula in the superior vena cava by switching 1995 by The Society of Thoracic Surgeons /95/$ (95)00130-D

2 1196 KITAMURA ET AL Ann Thorac Surg OPERATION FOR TYPE A AORTIC DISSECTION 1995;59: Membrane oxygenator Roller pump Fig 1. Antegrade selective cerebral perfusion was introduced in March Blood flow rate at 8 to 10 ml kg 7. rain-7 was maintained by two small roller pumps after the induction of deep hypothermia, and blood pressure in the bilateral superficial temporal arteries was controlled at 40 to 60 mm Hg on the average. (Ao - aorta; RA = right atrium; SVC = superior vena cava.) aortic valvular cusps were evaluated, and aortic valvuloplasty or aortic valve replacement was applied if necessary. If annuloaortic ectasia and aortic regurgitation were observed with aortic dissection, the whole aortic root was reconstructed with a composite graft by original or modified Bentall's procedure [18, 19]. In patients without aortic arch reconstruction, the distal aortic cuff at the end of ascending aorta was oversewn with double-layered Teflon felts and anastomosed to the tubular graft. For patients with an arch tear, aortic arch repair was performed under antegrade or retrograde selective cerebral perfusion with deep hypothermia. Low-flow perfusion of the lower body (20 to 30 ml/kg) was continued and open distal anastomosis [5, 20] with balloon occlusion of the descending aorta usually was applied. Major branches of aortic arch were reconstructed en bloc or separately according to the extension of the arch dissection. In patients with major abdominal branches perfused from the false lumen of the aortic dissection, a fenestration technique or a double-barrel repair was applied at the position of the distal anastomosis [19]. Follow-up and Statistical Analysis The follow-up interval of 84 operative survivors was from 0.2 to 21.6 years with a mean follow-up of 7.2 years. The information on all patients was confirmed by contacting a tube clamp to either the outflow or inflow portion, and mean pressure of the superior vena cava was less than 25 mm Hg. During either form of cerebral perfusion, low-flow perfusion (20 to 30 ml.kg 1.min 1) of the lower body was continued as long as possible. Operative Techniques In operations for type A aortic dissection, the ascending aorta to the aortic arch was exposed through a median sternotomy. Cardiopulmonary bypass with femoral arterial perfusion was performed under moderate (26 to 28 C) or deep (18 to 20 C; with aortic arch repair) systemic hypothermia. Since 1977, intermittent crystalloid cardioplegia (every 30 to 40 minutes), continuous coronary perfusion of cold blood (4 C), and topical cooling with ice slush were performed for myocardial protection during aortic cross-clamping. Composition of the cardioplegic solution was 50 g/l glucose, 20 U/L insulin, 20 meq/l potassium chloride, 8.3 meqll sodium bicarbonate, and 4.4 g/l mannitol. The ascending aorta was incised longitudinally, and the intimal tear, aortic wall dissection, both coronary orifices, and the aortic valve were examined closely. In standard cases without extended dissection beyond coronary orifices, the proximal aortic cuff just above the coronary orifices was oversewn with double-layered Teflon felts before the anastomosis was performed with a tubular woven Dacron graft. Shape and coaptation of the Membrane oxygenator Roller pump Fig 2. Retrograde selective cerebral perfusion was used from November Retrograde selective cerebral perfusion with deep hypothermia was performed at approximately 300 ml/min through a cannula in the superior vena cava by switching a tube clamp to either the uptake or inflow portion, and the mean pressure of the superior vena cava was less than 25 mm Hg. (Ao = aorta; RA = right atrium; SVC - superior vena cava.)

3 Ann Thorac Surg KITAMURA ET AL ;59: OPERATION FOR TYPE A AORTIC DISSECTION Table 1. Causes of Early Death After Operation for Type A Aortic Dissection Period Cause of Early Death I II III Low cardiac output Bleeding Multiple organ failure Organ ischemia Brain damage Others Total the patients or their primary physicians in January No patient was lost during this follow-up period. Any postoperative death in the hospital after operation for aortic dissection was considered an early death. Regardless of the cause of death, all late deaths were counted for analysis of the follow-up data. We divided the patients into three period subgroups of type A aortic dissection according to the circulatory support techniques. Period I is from May 1972 to February 1985, before the introduction of selective cerebral perfusion techniques. Period II is between March 1985 and October 1990, when antegrade cerebral perfusion was used. Retrograde cerebral perfusion was performed from November 1990 to June 1993 (period III). Statistical significance of differences between categoric parameters were evaluated by X 2 contingency analysis. The average of continuous variable in each group was compared by analysis of variance and Student's t test. Postoperative survival was analyzed by the Kaplan- Meier actuarial method and compared among the subgroups by Cox-Mantel statistical analysis. A probability value less than 0.05 was considered to be statistically significant. Noted values are mean _+ standard deviation. Results In 102 operations for type A dissection, 30 Bentall's procedures and 12 aortic valve replacements were performed. Aortic arch repair was applied in 2 of 40 patients (5.0%) (2 early deaths) in period I, in 18 of 38 patients (47.4%) (5 early deaths) in period II, and in 23 of 24 patients (95.8%) (no early deaths) in period III. Duration of the cerebral perfusion was 112 _+ 46 minutes in 18 patients with antegrade cerebral perfusion in period II and 59 _+ 26 minutes in 24 patients with retrograde cerebral perfusion in period III; the difference in perfusion time was statistically significant between these two groups (p < 0.001). In operations for type A aortic dissection, early mortality in period I was 12.1% in 33 chronic patients and 57.1% in 7 acute patients. In period II, the mortality was 11.1% in 27 chronic patients and 54.5% in 11 acute patients. There was no statistically significant difference between the two period subgroups in acute and chronic patients, respectively. In contrast, 1 of 15 chronic patients u) ~e Type A Period III 91.7% 40 Type A Period I 54.4% 20 0 i I * I i I i I, I Years after operation Fig 3. Actuarial survival curves after operation for type A dissection. The 5-year actuarial survival was 59.7% in period I and 63.2% in period II (not significant), and the 3-year survival in period III was 91.7%. Actuarial survival in period III was significantly higher than those of periods I and II (p < 0.05). (6.7%) and none of 9 acute patients (0%) with retrograde cerebral perfusion died in period III, and the early mortality (4.2%) of this group was significantly lower than that of the period II group (p < 0.05). Causes of early death are listed in Table 1. Low cardiac output and bleeding were the main causes of death in period I; multiple organ failure, organ ischemia, and brain damage occurred in period II. In period III, only 1 patient with a residual descending aortic dissection of large false lumen and small true lumen showed perioperative organ ischemia. With respect to the long-term results after operation for aortic dissection, actuarial survival rate including all deaths (early, cardiac, and noncardiac deaths) was 66.0% at the 5th and 60.5% at the 10th postoperative year in a total of 102 patients with type A dissection. Figure 3 shows actuarial survival curves (including all deaths) of the three period subgroups of type A aortic dissection. The 5- and 10-year survival rates were 59.7% and 54.4% in period I and 63.2% and 58.9% in period II, respectively. This difference was not statistically significant. In period III, actuarial survival at the 3rd postoperative year was 91.7%, which was significantly higher than those in periods I and II (p < 0.05). Causes of late death are indicated in Table 2. Rupture Table 2. Causes of Late Death After Operation for Type A Aortic Dissection Period Cause of Late Death I II III Rupture of residual aneurysm Heart failure Multiple organ failure Others Total

4 1198 KITAMURA ET AL Ann Thorac Surg OPERATION FOR TYPE A AORTIC DISSECTION 1995;59: of the residual aneurysm was observed only in period I. The difference in the incidence of this fatal complication was statistically significant in period I versus I1 (p ~ 0.01) and in period I versus III (p < 0.01). Surgical repair of aortic arch with selective cerebral perfusion techniques in periods II and III reduced the risk of rupture of residual aneurysms. Multiple organ failure related to perioperative shock and organ dysfunction was one of the factors increasing late mortality in any period. Comment From the previous experience in many medical centers, temporary shunt techniques [1] for aortic arch repair are considered to be inappropriate because of the high incidence of fatal complications with brain damage. In recent years, intraoperative circulatory support generally is used for surgical treatment of type A aortic dissection involving the aortic arch. Hypothermic circulatory arrest is a valuable technique in aortic operations, but a safe duration of the arrest is considered to be less than 50 to 60 minutes [8, 21]. Current reports [21, 22] show that early postoperative mortality was 9% to 15% and the incidence of permanent brain damage was 3% to 7% after operation for thoracic aortic aneurysm or dissection with hypothermic circulatory arrest. Selective cerebral perfusion with hypothermia has been introduced as one of the circulatory supports during aortic operations with arch repair [5]. Recently, antegrade selective cerebral perfusion [5, 10] or retrograde cerebral perfusion [9, 17] has been used in many medical centers mainly in Japan. According to these reports, the duration limit of antegrade selective cerebral perfusion was 2 hours or more, and that of the retrograde perfusion technique was about 80 to 90 minutes. In some patients in the present study with retrograde cerebral perfusion, symptoms and signs of temporary cerebral dysfunction were observed when the duration was more than 80 minutes. But all patients with retrograde cerebral perfusion recovered their consciousness and were discharged from the hospital except 1 patient with perioperative organ ischemia. In contrast, 3 of 38 patients (7.9%) with antegrade cerebral perfusion showed permanent brain damage due to stroke. Since its initial experience [9], retrograde cerebral perfusion has shown the advantage of reverse blood flow for removal of air and debris to avoid cerebral emboli. Comparing antegrade and retrograde cerebral perfusion techniques, retrograde cerebral perfusion without cannulation of aortic arch branches provided an excellent operative view and made the time of arch repair shorter. Because the blood flow of retrograde cerebral perfusion is about 5 ml. kg 1. min l, half that of antegrade cerebral perfusion, and its distribution is different in each patient, profound hypothermia is considered to be necessary, and safe duration of the hypothermia might be extended with retrograde cerebral perfusion. Although the lower body including abdominal organs has a little longer time limit of hypothermic circulatory arrest, its ischemic injury would proceed as the arrest time is prolonged. Therefore, we have applied low-flow perfusion of the lower body during either antegrade or retrograde cerebral perfusion. However, 2 patients with antegrade cerebral and lower body perfusion for more than 2 hours suffered from postoperative multiple organ failure in period II. With these recent techniques of circulatory support, extended surgical procedures [3, 19] were applied more for type A aortic dissection with an arch tear. In our current surgical strategy for aortic dissection, aortic arch repair with retrograde cerebral perfusion usually is performed for type A dissection with an arch tear or dissection of arch branches. Needless to say, recent advances in diagnostic tools, such as transesophageal echography, magnetic resonance imaging, and three-dimensional computed tomography, and progress in surgical materials, artificial grafts, membrane oxygenators, and so forth have made significant improvements in surgical strategies and results. From the late results of this study, extended surgical repair of aortic arch with selective cerebral perfusion techniques reduced the incidence of rupture of residual aneurysrns just distal to the graft replacement. The retrograde cerebral perfusion technique also significantly decreased the incidence of permanent complications with brain damage. We conclude that overall surgical results of type A aortic dissection in this series improved with the introduction of retrograde cerebral perfusion and extended surgical procedures. References 1. DeBakey ME, McCollum CH, Crawford ES, et al. Dissection and dissecting aneurysms of the aorta: twenty-year follow-up of five hundred twenty-seven patients treated surgically. Surgery 1982;92: Haverich A, Miller DC, Scott WC, et al. Acute and chronic aortic dissections: determinants of long-term outcome for operative survivors. Circulation 1985;72(Suppl 2): Massimo CG, Presenti LF, Marranci P, et al. Extended and total aortic resection in the surgical treatment of acute type A aortic dissection: experience with 54 patients. Ann Thorac Surg 1988;46: Borst HG, Frank G, Schaps D. Treatment of extensive aortic aneurysms by a new multiple-stage approach. J Thorac Cardiovasc Surg 1988;95: 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 1981;32: Yun KL, Glower DD, Miller DC, et al. Aortic dissection resulting from tear of transverse arch: is concomitant arch repair warranted? J Thorac Cardiovasc Surg 1991;102: Crawford ES, Kirklin JW, Naftel DC, Svensson LG, Coselli JS, Sail HJ. Surgery for acute dissection of ascending aorta: should the arch be included? J Thorac Cardiovasc Surg 1992;104: Griepp EB, Griepp RB. Cerebral consequences of hypothermic circulatory arrest in adults. J Card Surg 1992;7: Ueda Y, Miki S, Kusuhara IG Okita Y, Tahata T, Yamanaka K. Surgical treatment of aneurysm or dissection involving the ascending aorta and aortic arch, utilizing circulatory arrest

5 Ann Thorac Surg KITAMURA ET AL ;59: OPERATION FOR TYPE A AORTIC DISSECTION and retrograde cerebral perfusion. J Cardiovasc Surg 1990; 31: Tsnchida K, Hashimoto A, Koyanagi H, et al. Medical versus surgical treatment for aortic dissections: early and late results in 106 patients [Abstract]. J Jpn Assoc Thorac Surg 1986;34: Hashimoto A. Long-term results over 10 years after surgery for chronic dissecting aneurysms of the aorta [Abstract]. Jpn Ann Thorac Surg 1991;11: Tsuchida K, Hashimoto A, Endo M, Koyanagi H. Perfusion of dominant left subclavian artery during thoracic aortic aneurysm operation. Ann Thorac Surg 1992;54: Daily PO, Trueblood HW, Stinson EB, Wuerflein RD, Shumway NE. Management of acute aortic dissections. Ann Thorac Surg 1970;10: Miller DC, Stinson EB, Oyer PE, et al. Operative treatment of aortic dissections: experience with 125 patients over a sixteen-year period. J Thorac Cardiovasc Surg 1979;78: Crawford ES, Crawford JL, Stowe CL, Sail HJ. Total aortic replacement for chronic aortic dissection occurring in patients with and without Marfan's syndrome. Ann Surg 1984;199: Kitamura N, Natsuaki M, Ishihara S, Hashimoto A, Koyanagi H. Experimental comparative evaluation of various cardioplegic solutions and clinical application of selective cor- onary perfusion with cold GIK solution [Abstract]. Jpn J Thorac Surg 1978;31: lmamaki M, Hashimoto A, Koyanagi H, et al. A clinical assessment of efficacy in continuous retrograde cerebral perfusion method [Abstract]. Jpn J Thorac Surg 1992;45: Bentall H, DeBono A. A technique for complete replacement of ascending aorta. Thorax 1968;23: Hashimoto A, Seino R. Simultaneous replacement of the aortic valve and the ascending aorta: its operative procedure, early and late postoperative results: especially for annuloaortic ectasia and dissecting aneurysm of the aorta [Abstract]. Jpn J Thorac Surg 1991;44: 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 1981;194: Ergin MA, Galla JD, Lansman SL, Quintana C, Bodian C, Griepp RB. Hypothermic circulatory arrest in operations on the thoracic aorta: determinants of operative mortality and neurologic outcome. J Thorac Cardiovasc Surg 1994;107: Galloway AC, Colvin SB, Grossi EA, et al. Surgical repair of type A aortic dissection by the circulatory arrest-graft inclusion technique in sixty-six patients. J Thorac Cardiovasc Surg 1993;105: Notice From the Southern Thoracic Surgical Association The Forty-second Annual Meeting of the Southern Thoracic Surgical Association will be held at the Hyatt Regency Hill Country Resort, San Antonio, Texas, November 9-11, The Postgraduate Course will be held the morning of Thursday, November 9, 1995, and will provide in-depth coverage of thoracic surgical topics selected primarily as a means to enhance and broaden the knowledge of practicing thoracic and cardiac surgeons. Applications for membership should be completed by August 1, 1995, and forwarded to Carolyn E. Reed, MD, Membership Committee Chairman, Southern Thoracic Surgical Association, 401 North Michigan Avenue, Chicago, IL D. Glenn Pennington, MD Secretary-Treasurer Southern Thoracic Surgical Association 401 North Michigan Avenue Chicago, IL