Material and Methods Between November, 1966, and December, 1984, 45 patients

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1 Clmp/Repak A Safe Technique for Treatment of Blunt Injury to the Descending Thoracic Aorta Kenneth L. Mattox, M.D., Madelyn Holzman, B.A., Laurens R. Pickard, M.D., Arthur C. Beall, Jr., M.D., and Michael E. DeBakey, M.D. ABSTRACT Debate exists with regard to the use of pump bypass, shunt bypass, or clamphepair techniques in treating injuries to the descending thoracic aorta. The objective in using any of these techniques is to minimize the complications of paraplegia and renal failure, while achieving the lowest possible mortality. During an eighteen-year period, 45 patients were seen with acute blunt injury to the descending thoracic aorta. The shunt bypass method of repair was used in 1; pump bypass in 8; and clamphepair in 23. There were desperate unsuccessful attempts to resuscitate and control hemorrhage in 13 patients, 1 of whom was placed on portable pump bypass. Thirty-two patients survived resuscitation and operation, and 26 were long-term survivors. Among surviving patients with permanent paraplegia, 2 underwent pump bypass and 1, the clamphepair technique. Four other patients were seen with paraplegia or paresis and had reversal of the paralysis. The clamphepair technique was used in these patients with clamp times ranging from 35 to 62 minutes (mean, 47.4 f 13.3 minutes). Renal failure did not occur in any patient, despite clamp times of up to 62 minutes (mean, 37.5 minutes). Excluding patients seen in a moribund condition, mortality most often was secondary to neurological or multisystem injury. Debate continues concerning intraoperative management of this highly lethal vascular injury. The data presented here support the historical composite experience that clamphepair is a safe and efficacious technique that minimizes paraplegia and mortality. In both military injuries and recently documented civilian injuries, immediate death occurs in more than 85% of patients with acute blunt injury to the descending thoracic aorta [I, 21. Among the 15% who survive the initial injury, the &hour untreated, in-hospital mortality approaches 50% [3]. These patients commonly have multisystem injury. The issues relative to blunt injury to the descending thoracic aorta include prevention, early transport to a trauma center, recognition, timing of operations, and techniques of intraoperative management. From the Cora and Webb Mading Department of Surgery, Baylor College of Medicine, and the Ben Taub General Hospital, Houston, TX. Presented at the Twenty-first Annual Meeting of The Society of Thoracic Surgeons, Phoenix, AZ, Jan 21-23, Address reprint requests to Dr. Mattox, Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX i7030. Complications are usually related to associated injuries. It has been proposed that paraplegia is related to the extent of injury, number of intercostal arteries involved with the injury, technique of protection from distal ischemia, length of cross-clamp time, and other factors (41. This study focuses mainly on death and paralysis and their relationship to the technique of operative repair. Material and Methods Between November, 1966, and December, 1984, 45 patients with acute blunt injury to the descending thoracic aorta were seen at Houston s Ben Taub General Hospital (Table 1). Two patients were transferred from other hospitals, and the greatest time interval between injury and operation was 50 hours. Forty patients underwent thoracotomy within 6 hours of injury. There were 37 male and 8 female patients ranging from 16 to 66 years of age, with a mean age of 32 If: 13.2 years. Ten patients arrived with agonal respirations and had thoracotomy for resuscitation in the emergency center. Thirty-four patients underwent arteriography, all but 5 through the retrograde femoral route. Nine patients underwent attempted repair using a pump bypass technique, either left atrium to femoral artery or femoral vein to femoral artery, one of which was a desperate and unsuccessful attempt at resuscitation. (Throughout this report, pump bypass pertains to both of these techniques.) One injury was repaired with the aid of a Gott shunt inserted in the ascending aorta and the descending thoracic aorta distal to the injury. Isolation of the injury between vascular clamps and (without bypass tubes or pumps) repair using end-toend anastomosis or interposition Dacron grafting were accomplished in 23 patients. In 12 other patients, this clamphepair technique was unsuccessfully attempted in the emergency center or the operating room as a desperate measure to control a free rupture into the pleural cavity. Perioperative communication with the anesthesiologist assured adequate numbers of intravenous lines, control of the airway (at times with a double-lumen endotracheal tube), and close correlation in the use of pharmacological agents. Volume replacement was timed in concert with cross-clamping and cross-clamp release. Maintaining the mean arterial pressure between 90 and 120 mm Hg at all times during the procedure has been the objective since the clamphepair technique became the standard preferred treatment in

2 457 Mattox et al: ClamplRepair for Descending Aortic Injury Table I. Operative Method for Repair of Descending Thoracic Aortic Blunt Injury" Method No. of Patients No. with Paraplegia Clamplrepair 23 (5) 3 (2) (planned) Resuscitation 12 (12)? aortic clamping (desperate) Pump bypass 9 (2) 2 (0) Shunt bypass 1 0 Total 45 (19) 5 (2) "Numbers in parentheses are deaths. Results Thirteen patients were moribund on arrival at the emergency center. Eight of them underwent thoracotomy in the emergency center, 4 went to the operating room immediately, and 1 patient had portable pump bypass. Despite desperate attempts to gain control of exsanguinating hemorrhage, all these patients died. Death resulted from hemorrhage, multiple trauma, and extensive central nervous system injury. Thirty-two patients survived resuscitation and operation, and form the basis of this report. Of these 32 patients, 6 died in the intensive care unit within thirty days of operation: 4 of central nervous system injury, 1 of respiratory insufficiency, and 1 of multisystem failure. Outcome for the patients surviving operation. (ICU = intensive care unit.) / J-k SHUNT BYPASS, The 26 patients who were dismissed from the hospital were alive and well (except for 3 paraplegic patients) at last follow-up, which ranged from four months to ten years. The motor and sensory function of the lower extremities was evaluated preoperatively. Two patients were in severe coma, and evaluation of the spinal cord was impossible. Twenty-five patients had no evidence of motor or sensory loss preoperatively. Among 5 patients with lower extremity paralysis, 1 had transection of the spinal cord. The paraplegia in the remaining 4 patients, including 2 with pseudocoarctation syndrome, was presumably due to ischemia of the spinal cord resulting from transection of the descending thoracic aorta (Figure). Postoperatively, the patients were evaluated for evidence of motor and sensory loss in the lower extremities. Five patients had postoperative paralysis, and 2 of them died in the intensive care unit (Table 2). Using Fischer's exact test, the difference in clamp times between the clamphepair technique and pump bypass was not significant in regard to both paraplegia ( p = 0.58) and death ( p = 0.29). One patient had transection of the spinal cord preoperatively, and the other arrived at the hospital in a coma. Postoperative hoarseness secondary to left vocal cord paralysis occurred in 2 patients. This condition resolved in six weeks in 1 patient and was permanent in the other. Four patients required prolonged respiratory support because of pulmonary contusion, and 6 other patients had complications secondary to orthopedic or abdominal injuries. There were no renal complications, except in the patient who died of multisystem failure. WE UROLOGICALLY INTACT PRE-OP 1251 DIE0 IN ICU I11 1 I RESUSCITATION I SURVIVED (32) I PRE.OP PARALYSIS "INAL TRANSECTION - CLAMP I REPAIR Ill SplNALCoRD "ISCHEMIA" - CLAMP/ REPAIR I 4 PARAPLEGIA REMAINE 0 Ill RE VE RSAL PARAPLEGIA 141 DIED IN ICU Ill HOME OK I41 COMA PRE OP 121 CLAMP I RE PAIR (11 PUMP BYPASS (11 POST-OP PARAPLEGIA DIED IN ICU (0 (11 POST.OP PARAPLEGIA HOME PARAPLEGIC 111 (11

3 ~~ 458 The Annals of Thoracic Surgery Vol 40 No 5 November 1985 Table 2. Clamp Times and Operative Method for Patients Surviving Operation Clamp Times Technique No. of Patients Range (min) Mean (min) No. of Deaths Paraplegia Clamphepair Dacron interposition b End-to-end Pump (all Dacron interposition) Shunt (end-to-end) Total or mean b The difference in clamp times between pump bypass and clamp and repair was not significant in regard to paraplegia or death. bt~o of these patients died in intensive care unit. Table 3. Clamp Times and Outcome in Patients Surviving Operation No. with Clamp No. with Reversal of Times No. of No. of Postoperative Preoperative (min) Patients Deaths Paraplegia Paralysis Total There were 2 deaths among these patients (see Figure). All patients with postoperative cerebral compromise had either extensive head injury at the time of admission or were heparinized for pump bypass. Heparinization resulted in deterioration of cerebral neurological status compared with the preoperative condition. In the last eight years, no patient in whom the clamphepair technique was used had neurological complications in the brain, spinal cord, or peripheral nerves. Five patients had paraplegia or paresis of the lower extremities on arrival at the hospital; the condition was associated with a pseudocoarctation syndrome (intimal flap at injury, lower extremity hypotension, and decreased femoral pulses) in 2 patients and transection of the spinal cord in 1 patient. Reversal of paraplegia occurred in 4 patients by two weeks postoperatively, and all were ambulatory when last seen at follow-up. The aortic arch between the left carotid and left subclavian arteries, the left subclavian artery, and the descending thoracic aorta distal to the injury were clamped initially in all patients. Occasionally the proximal clamps were moved beyond the ligamentum arteriosum when possible for safe repair. In 1 patient, the proximal clamp was placed between the right and left carotid arteries because of the proximal extent of the aortic tear. The clamp times for all patients ranged from 14 to 62 minutes, with a mean of 37.5 k 11.4 (Table 3). Patients with no neurological deficit postoperatively had clamp times ranging from 14 to 60 minutes, with a mean of minutes. The 5 patients who had paraplegia postoperatively (all prior to 1975) had clamp times ranging from 30 to 45 minutes, with a mean of minutes (see Table 3). For 4 patients who were seen with paraplegia or paresis and had reversal of paraplegia, clamp times ranged from 35 to 62 minutes, with a mean of minutes. The relationship between the method of intraoperative management and the incidence of paraplegia was examined. Among the 23 patients undergoing the clamp/repair technique, 5 were paraplegic preoperatively (1 from transection of the spinal cord). Four had reversal of their paralysis postoperatively. Two of the remaining 18 patients managed with the clamphepair technique were paraplegic postoperatively, including 1 who was in a coma preoperatively and died in the intensive care unit. Among the 8 patients in the pump bypass group, 2 had paraplegia following operation, 1 of whom was in a coma preoperatively. The 1 patient in whom the Gott shunt was used had no neurological deficit. All patients with paraplegia had profound hypotensive episodes, either at the time of preoperative rupture of a contained hematoma or on completion of the procedure when the aortic clamp was released. Such dramatic identifiable hypotensive episodes were not apparent among patients without postoperative paralysis. Since 1975, no patient surviving resuscitation and operation has gone home from the hospital with paralysis. The clamp times among patients surviving operation ranged from 14 to 62 minutes. One patient (clamphepair technique) with a clamp time of 24 minutes had postoperative paraplegia. Although 4 patients (2 with pump bypass and 2 with clamphepair) with clamp times of between 36 and 45 minutes became paraplegic, 4 others with preoperative neurological deficits and clamp times of between 31 and 62 minutes had reversal of their preoperative paralysis. Comment The medical literature contains numerous articles on blunt injury to the descending thoracic aorta. The natural history, pathophysiology, techniques of impact en-

4 459 Mattox et al: ClampRepair for Descending Aortic Injury ergy attenuation, mortality before reaching the hospital, indications for arteriography, approach to imaging and diagnosis, sequencing of operation, techniques for preventing distal ischemia, and management of complications and associated injuries are some of the issues discussed in these reports. The present review of the data from Ben Taub General Hospital addresses only the issue of intraoperative management. Many articles in the literature involve very small series, present combined series of both acute and chronic injuries, or "mix" dissecting aneurysms, degenerative lesions, and traumatic lesions of the descending thoracic aorta. Those series that clearly delineated the deaths and complication rates for either acute or chronic blunt injuries to the descending thoracic aorta were analyzed and compared with the Ben Taub General Hospital series. Although some reports suggest that the use of pump bypass or a Gott shunt provides protection against ischemia to the kidneys and to the spinal cord, these methods do not prevent paraplegia or renal failure. Furthermore, many other factors are thought to contribute to paraplegia. They include the presence of preoperative neurological deficit, the number of intercostal arteries that must be sacrificed because of the extent of injury, the presence of pseudocoarctation syndrome, hypotensive episodes at the time of hematoma rupture and exsanguination, hypotension at the time of clamp release at the end of the procedure, and possibly the length of the cross-clamp time [ It has been proposed that a cross-clamp time of 30 minutes provides a safe margin against paraplegia and that shunting techniques should be employed for longer cross-clamp times [7,12, 131. However, the use of shunting procedures in no way eliminates risk to the area of the spinal cord between the clamps [ In this review, 4 patients with clamp times longer than 30 minutes had reversal of preoperative paraplegia. Only 2 patients known to be neurologically intact preoperatively and with clamp times longer than 30 minutes had postoperative paraplegia. One of these patients underwent repair on pump bypass. Patients requiring cross-clamp times greater than 30 minutes or requiring Dacron interposition grafts have more extensive injuries than those requiring shorter clamp times or end-to-end anastomosis. Patients with such extensive injury, including the requirement to ligate more damaged intercostal arteries, have a greater potential for altered flow to the anterior spinal artery. The length of the cross-clamp time is less crucial than other factors beyond the control of the surgeon. The priority objectives in maximizing safety during intraoperative management include prevention of (1) stress on the heart during aortic clamping, (2) intracranial bleeding, (3) paraplegia, and (4) renal insufficiency (181. Maximum protection can be afforded through close communication among surgical, anesthetic, and nursing personnel, with the objective of keeping the mean arterial pressure between 90 and 120 mm Hg [5]. This objec- tive can be accomplished by effective pharmacological and blood volume management. The surgeon should communicate with the anesthesiologists when the clamps are being applied to the aorta and before they are to be removed. Although pump bypass was used in early series of patients having operative repair of transection of the aorta, an increased mortality was noted when transection was associated with concomitant head injury [W, 19-21]. Heparinization increases morbidity and mortality in patients with multisystem injuries, multiple fractures, and uncontrollable bleeding. It also increases the incidence of suture line bleeding from aortic anastomoses. Recent series have rarely employed pump bypass and total-body heparinization. Our series is not representative in that the mortality is lower than that reported in the literature (Table 4). A variety of heparin-bonded shunts have been proposed to eliminate the problem of total-body heparinization while affording some degree of protection to prevent distal ischemia [ Such shunts are not without problems. There may be difficulties with inserting the shunt because of patient position, presence of periaortic hematoma, and time constraints dictated by expanding, pulsatile, uncontrolled hematoma [7, 151. Additional problems are intraoperative or postoperative bleeding at cannulation sites or false aneurysm formation at these sites [6, 201. There is extensive experience with operation on the descending thoracic aorta to support the safe use of the clamphepair techniques in acute and chronic traumatic disruption of the descending thoracic aorta. In the literature, there have been numerous reports of patients who had permanent total exclusion of traumatic or degenerative diseases. This total exclusion from the left subclavian artery through the midpart of the descending thoracic aorta did not result in paraplegia [ Therefore, the mere clamping or exclusion of a segment of descending thoracic aorta does not, a priori, result in predictable neurological deficit. Prior to series involving pump or shunt bypass, there were several reports of successful management of aortic injuries with the clamp/ repair technique [ll, 311. At least one report in the mid- 1960s related successful use of the clamphepair technique and a 45-minute clamp time with reversal of preoperative paraplegia [ 111. Furthermore, the use of clamp/repair for atherosclerotic, dissecting, and chronic aneurysms of traumatic origin of the descending thoracic aorta encouraged its application in acute traumatic transections [14, 32, 331. It has been suggested that the "optimal treatment" of traumatic transection of the descending thoracic aorta, especially if the surgeon is not facile and experienced, is the use of a bypass shunt to protect the spinal cord and kidneys from possible ischemia and the complications of renal insufficiency and paraplegia [15, 341. Renal insufficiency is rarely described following repair of this traumatic lesion. The important issues relate to the questions of mortality and the incidence of paraplegia follow-

5 460 The Annals of Thoracic Surgery Vol 40 No 5 November 1985 Table 4. Results Follm'ng Operative Treatment of Acute Traumatic Blunt Injury to Descending Thoracic Aorta Reference Pump ClamplRepair Shunt Total No. of Para- No. of Para- No. of Para- No. of Para- Patients Died plegia Patients Died plegia Patients Died plegia Patients Died plegia Schmidt and Jacobson [37l Appelbaum et a1 [34] Stavens et a1 [38] Donahoo et al [24] Turney et a1 [16] Lawrence and Ehrenhaft [25] Vasko et al [21] Kirsh et a1 [15] Akins et al [39] Wilson et al [40] Ketonen et al [41] Verdant et a Williams et a1 [4] Soyer et a1 [35] Mucha [personal communication] Pezzella et al [43] Avery et a1 [44] Mattox et a1 [present report] Total % AP%" 'Adjusted paraplegia = number of paraplegic patients divided by number of survivors. ing the use of a pump, a shunt, or clamphepair techniques. A collected review of 571 acute (see Table 4) and chronic (Table 5) traumatic injuries to the descending thoracic aorta reveals an overall mortality of 16.5% and a rate of paraplegia of 5.4%. The adjusted rate of paraplegia, obtained by dividing the number of paraplegic patients by the number of survivors, revealed an overall "adjusted incidence of paraplegia of 6.5%. Among 387 case reports of acute injury with enough information for analysis, there were a 20.7% mortality and a 6.9% adjusted rate of paraplegia. The mortality for acute injuries to the descending thoracic aorta for pump, clamphepair, and shunt was 32.6%, 13.3%, and 15.1%, respectively. For pump, clamphepair, and shunt techniques, the adjusted paraplegia rate was 4.5%, 8.3%, and 10.3%, respectively. In the treatment of chronic traumatic injuries of the descending thoracic aorta, the safety of the clamp/ repair technique is established in the literature summation (see Table 5). The diverse and somewhat conflicting results obtained with varying techniques and clamp times point out even more clearly that clamp time alone cannot be the determining factor in regard to postoperative paraplegia. Using the chi-square analysis, the cumulative mortality for acute injury is significantly less for the pump repair than for either clamphepair or shunt (p = < 0.001). Among the three groups, the rate of paraplegia for acute injuries is not significant (p = 0.168). For repair of chronic aortic injuries, the difference among the three techniques was not significant either for mortality (p = 0.345) or paraplegia (p = 0.096). Although controversy still surrounds the subject of intraoperative management in acute traumatic injury of the descending thoracic aorta, no technique has proven to be without mortality or the dreaded complication of paraplegia [MI. The Ben Taub General Hospital experience speaks for the safety of the clamphepair technique in relation to the death rate and incidence of paraplegia. No patient has been discharged from the hospital with paraplegia since 1976, when we began using the clamp/ repair technique exclusively. The development of paraplegia relates to many variables, the least of which may be clamp time or prevention of ischemia to the spinal cord with a shunt. The review of the literature bears the same support for the clamphepair technique [I, 4, 16, 18, 21, 33-36].* The clampkepair technique decreases clamp times, minimizes dissection, and allows more rapid control of the aorta. Furthermore, the technique avoids any risks of complications from the shunt bypass. 'Mucha P: Personal communication, Mayo Clinic, 1983.

6 461 Mattox et al: ClampRepair for Descending Aortic Injury Table 5. Results Following Operative Treatment of Chronic Traumatic Blunt Injury to Descending Thoracic Aorta Pump ClampRepair Shunt Total No. of Para- No. of Para- No. of Para- No. of Para- Reference Patients Died plegia Patients Died plegia Patients Died plegia Patients Died plegia Appelbaum et a1 [34] Finkelmeier et a1 [45] Ketonen et al [41] Vasko et a1 [21] McCollum et al [36] Groves [46] Stavens et a1 [38] Soyer et al [35] Williams et a1 [4] Heberer [47l Verdant et a1 [42] Lawrence and Ehrenhaft [25] Pezzella et a1 [43] Total % AP%" 'Adjusted paraplegia = number of paraplegic patients divided by number of survivors. We recommend clamphepair as a safe technique for intraoperative management of acute traumatic injury to the descending thoracic aorta. Supported in part by Grant No. &?4-101 from the Texas Trauma Research Foundation. Computational assistance was provided by the CLINFO Project, funded by the Division of Research Resources of the National Institutes of Health under Grant No. RR-OO350. References 1. Parmley LF, Mattingly WT, Manion WC, Jahnke EJ Jr: Nonpenetrating traumatic injury of the aorta. Circulation , Mattox KL: Invited commentary on blunt injury to the descending thoracic aorta. World J Surg 4551, Plume S, DeWeese JA: Traumatic rupture of the thoracic aorta. Arch Surg , Williams TE, Vasko JS, Kakos GS, et a1 Treatment of acute and chronic traumatic rupture of the descending thoracic aorta. World J Surg 4545, Crawford ES, Palamara AE, Saleh SA, et al: Aortic aneurysms: current status of surgical treatment. Surg Clin North Am 59597, Culliford AT, Ayvaliotis B, Shemin R, et al: Aneurysm of the descending aorta. J Thorac Cardiovasc Surg e Hilgenberg AD, Rainer WG, Sadler TR Jr: Aneurysm of the descending thoracic aorta: replacement with the use of a shunt or bypass. J Thorac Cardiovasc Surg 81:818, Griffith GL, Mattingly WT, Todd EP Current diagnosis and management of blunt thoracic aortic trauma. J K Med Assoc 79588, Slaney G, Ashton F, Abrams LD Traumatic rupture of the aorta. Br J Surg 53361, Spencer FC, Guerin PF, Blake HA, et al: A report of fifteen patients with traumatic rupture of the thoracic aorta. J Thorac Cardiovasc Surg 41:1, 1%1 11. DeMuth WE Jr, Roe H, Wallace H: Immediate repair of traumatic rupture of thoracic aorta. Arch Surg 91:602,196!5 12. Laschinger JC, Cunningham JN Jr, Nathan IM, et al: Experimental and clinical assessment of the adequacy of partial bypass in maintenance of spinal cord blood flow during operations on the thoracic aorta. Ann Thorac Surg 36:417, Katz NM, Blackstone EH, Kirklin JW, Karp RB: Incremental risk factors for spinal cord injury following operation for acute traumatic aortic transection. J Thorac Cardiovasc Surg 81669, Crawford ES, Rubio PA: Reappraisal of adjuncts to avoid ischemia in the treatment of aneurysms of descending thoracic aorta. J Thorac Cardiovasc Surg 66:693, Kirsh MM, Behrendt DM, Orringer MB, et al: The treatment of acute traumatic rupture of the aorta. Ann Surg 18438, Tumey SZ, Attar S, Ayella R, et al: Traumatic rupture of the aorta: a five-year experience. J Thorac Cardiovasc Surg 72727, Stafford G, O'Brien MF: Traumatic rupture of the thoracic aorta. Aust NZ J Surg 47175, Roberts FJ, Nora JD, Hughes WA, et al: Cardiac and renal responses to cross-clamping of the descending thoracic aorta. J Thorac Cardiovasc Surg , Saylam A, Melo JG, Ahmad A, et al: Early surgical repair in traumatic rupture of the thoracic aorta. J Cardiovasc Surg (Torino) 21295, Frantz PT, Murray GF, Shallal JA, Lucas CL Clinical and experimental evaluation of left venhiculoiliac shunt bypass during repair of lesions of the descending thoracic aorta. Ann Thorac Surg 31551, Vasko JS, Raess DH, Williams TE Jr, et al: Nonpenetrating trauma to the thoracic aorta. Surgery 82:400, 1977

7 462 The Annals of Thoracic Surgery Vol 40 No 5 November Gott VL: Heparinized shunts for thoracic vascular operations (editorial). Ann Thorac Surg 14:219, Wakabayashi A, COMO~~Y JE, Stemmer EA, et ak Heparinless left heart bypass for resection of thoracic aneurysms. Am J Surg 130:212, Donahoo JS, Brawley RK, Gott VL: The heparin-coated vascular shunt for thoracic aortic and great vessel procedures: a ten-year experience. Ann Thorac Surg 23507, Lawrence MS, Ehrenhaft JL: Trauma to the thoracic aorta. J Iowa Med Soc 55637, Murray GF, Young WG Jr: Thoracic aneurysmectomy utilizing direct left ventridofemoral shunt (TDMAC-heparin) bypass. Ann Thorac Surg 21:26, Carpentier A, Deloche A, Fabiani JN, et al: New surgical approach to aortic dissection: flow reversal and thromboexclusion. J Thorac Cardiovasc Surg 81659, Ergin MA, OConnor JV, Blanche C, Griepp RB Use of stapling instruments in surgery for aneurysms of the aorta. Ann Thorac Surg 36:161, Hargrove WE 111, Edmunds LH Jr: Management of infected thoracic aortic prosthetic grafts. Ann Thorac Surg 3772, Pickard LR, Mattox KL, Espada R, et a1 Transection of the descending thoracic aorta secondary to blunt trauma. J Trauma 17749, Passaro E, Pace WG: Traumatic rupture of the aorta. Surgery 46:787, Garcia-Rinaldi R, Defore WW Jr, Mattox KL, et al: Unimpaired renal, myocardial and neurologic function after cross-clamping of the thoracic aorta. Surg Gynecol Obstet 143:249, Najafi H, Javid H, Hunter J, et al: Descending aortic aneurysmectomy without adjuncts to avoid ischemia. Ann Thorac Surg 30:326, Appelbaum A, Karp RB, Kirklin JW Surgical treatment for closed thoracic aorta injuries. J Thorac Cardiovasc Surg 71:458, Soyer R, Brunet A, Piwinica A, et al: Traumatic rupture of the thoracic aorta with reference to 34 operated cases. J Cardiovasc Surg (Torino) 2103, McCollum CH, Graham JM, Noon GP, DeBakey ME: Chronic traumatic aneurysms of the thoracic aorta: an analysis of 50 patients. J Trauma 19248, Schmidt CA, Jacobson JG: Thoracic aortic injury. Arch Surg 119:1244, Stavens B, Hashim SW, Hammond GL, et al: Optimal methods of repair of descending thoracic aortic transections and aneurysms. Am J Surg 145:508, Akins CW, Buckley MJ, Daggett W, et al: Acute traumatic disruption of the thoracic aorta: a ten-year experience. Ann Thorac Surg 3135, Wilson RF, Arbulu A, Bassett JS, et al: Acute mediastinal widening following blunt chest trauma. Arch Surg 104:551, Ketonen P, Javinen A, Luosto R, et al: Traumatic rupture of the thoraac aorta.!sand J Thmc cardiovasc Surg 14233, Verdant AG, Mercier CH, Page AA, et al. Aneurysms of the descending thoracic aorta: treatment with the Gott shunt. Can J Surg 24594, Pezzella AT, Todd El', Dillon ML, et al: Early diagnosis and individualized treatment of blunt thoracic aortic trauma. Am Surg M699, Avery JE, Hall DP, Adams JE, et a1 Traumatic rupture of the thoracic aorta. South Med J n.1238, Finkelmeier BA, Mentzer RM, Kaiser DL, et a1 Chronic traumatic thoracic aneurysm. J Thorac Cardiovasc Surg M257, Groves LK Traumatic aneurysm of the thoracic aorta. N Engl J Med , Heberer G: Ruptures and aneurysms of the thoracic aorta after blunt chest trauma. J Cardiovasc Surg (Torino) 12:115, Beall AC, Arbegast NR, Ripepi AC, et al: Aortic laceration due to rapid deceleration. Arch Surg 98595, 1969 Discussion DR. JOSEPH N. CUNNINGHAM, JR. (BrM~klp, m): Dr. Mattox and his colleagues are to be congratulated for updating us on their eighteen-year experience with a large group of patients who were appropriately managed intraoperatively following traumatic aortic rupture. It was a pleasure to read their manuscript, which outlines their data clearly and compares it with more than twenty other series involving almost 600 patients with acute and chronic aortic injuries. Their data show an 8% incidence of paraplegia among 25 patients who were neurologically intact preoperatively, and are impressive in the notation that 4 patients with preexisting spinal cord ischemia exhibited early reversal of paraplegia after successful aortic repair. Such results certainly militate against any criticism relative to management of this very complex condition, and I again congratulate them on their results, with particular reference to the total absence of paraplegia in any patient since It is understandable that the authors endorse a simple clamp/ repair approach, particularly since the effectiveness of shunts or distal bypass could not be determined. Here lies a major controversy. The Maimonides-St. Vincent's Hospital experience since 1977 involves 17 similar patients, many operated on by my associate, Dr. Acinapura. Our approach has been to employ a shunt or distal bypass in all patients. No patient in this group has sustained paraplegia, and there have been no deaths despite the fact that one-third of the patients had multisystem injury. Since 1982, we have employed routine spinal cord monitoring as an adjunct during both emergent and elective aortic repairs. This methodology allows identification of critical intercostal arteries and monitors the adequacy of distal perfusion. Our experience does suggest a relationship between crossclamp time, loss of evoked potentials, and paraplegia. No patient in this series sustained paraplegia if somatosensory evoked potentials were maintained, while loss of conduction during operation was associated with a 31% incidence of paraplegia. No patient experienced neurological injury if loss of somatosensory evoked potentials was limited to less than 30 minutes. However, a 71% incidence of paraplegia occurred when disappearance of evoked potentials exceeded this interval. We therefore advocate intraoperative monitoring of evoked potentials and distal perfusion when possible during thoracic aortic repair. I have three questions for Dr. Mattox. First, are you currently monitoring somatosensory evoked potentials during either urgent or elective aortic repairs? Second, have you used an intraluminal Dacron graft in these patients so as to limit crossclamp time? Finally, would you consider as an alternative to systemic heparinition in these badly injured patients the use of left atrium-femoral artery bypass or venoarterial bypass through heparin-bonded tubing? DR. THOMAS E. WILLIAMS, JR. (Columbus, OH): I support Dr. Mattox and his colleagues in the approach they have taken to the management of patients with traumatic rupture of the descending thoracic aorta. My co-worker, John Vasko, introduced the technique to our group in Since that time, we have

8 463 Mattox et al: Clamp/Repair for Descending Aortic Injury carried out this type of repair in 16 patients with no deaths. Three patients experienced paresis, and all have recovered. One was a 23-year-old man who had a 45-minute cross-clamp time and whose aorta ruptured at the time the clamps were applied. He also sustained ventricular fibrillation and had hypotension during the period of cross-clamping. In the other 2 patients, the cross-clamp times were 34 minutes and 43 minutes. In 1 of these patients, two intercostal vessels had been avulsed in the injury and could not be repaired. In the other, there was an anomalous origin of the right vertebral artery from the aorta distal to the area of transection. We believe, and I think Dr. Mattox would agree, that factors other than cross-clamp time are important. These factors include the anatomy of the intercostal vessels that are lost and the presence of anomalies of the proximal spinal cord circulation. One other point that I emphasize is the importance of adequate exposure. We use double-lumen tubes, make a very generous incision, and are flexible about approaching the aorta, either coming from the pericardial sac posteriorly to gain control or coming down the anterior surface of the subclavian artery to get the clamp in place before trouble breaks loose. We strongly support the approach used by Dr. Mattox's group. DR. ROBERT F. WILSON (Detroit, MI): My colleagues and I have had a long-standing argument with Dr. Mattox about the proper management of traumatic rupture of the aorta. In our own and adjacent states, a number of malpractice suits have been generated because of the poor results of operations done by surgeons who are not particularly experienced in thoracic aortic surgery but who attempt to use the clamphepair technique. 1 think that when Dr. Mattox and other experienced surgeons use this technique, it is a different story and their good results reflect this. The poor results of less experienced surgeons do not get published. Surgeons less familiar with trauma, and particularly with clamphepair, cannot prepare the patient as well or repair the aorta as rapidly. In many instances they also lack the needed support personnel. But when they read the reports by Dr. Mattox and his co-workers, they are encouraged to perform this operation, and they obtain bad results. In the past three years, we have seen 6 patients with paraplegia caused by other surgeons in surrounding areas who used the clamphepair technique. A review of the literature reveals many more cases than Dr. Mattox has described. There are a total of at least 1,100 cases of traumatic rupture of the aorta, and at least 700 were treated during the acute phase. Most of these studies point out that the rate of paraplegia is highest with the clamplrepair technique. We have recently begun to employ the so-called heparinless bypass method but with a quarter of the usual dose of heparin. This dose seems to reduce the amount of bleeding from associated injuries, and there is Little danger of clots forming in the lines. DR. RAYMOND A. DIETER, JR: (Glen Ellyn, IL): We in the community hospitals west of Chicago have seen a number of patients with these types of injuries. I have questions about two major areas of concern. The first involves the temperature of the patient when he or she is brought to the hospital. We have worried about hypothermia and possible hypothermic problems when the clamps are removed, and about the results in either the traumatic or the atherosclerotic aorta, particularly when the abdomen has also been opened for repair. The second involves the possible causes of the paraplegia. If the intercostals tom during the accident may lead to hemorrhage when the mediastinum is opened, could this hemorrhage create a steal situation in which blood is taken away from the spinal cord and subsequent paralysis results? I enjoyed the presentation. DR. MATTOX: Dr. Ralph Alley, former secretary and president of this Society as well as the recipient of the Distinguished Service Award, has had a long-standing interest in this lesion. He requested an advance copy of our manuscript and apologized for having to leave early. Dr. Alley emphasizes that there are pitfalls in the use of the shunt, including prior knowledge of its use, as well as sluggish flow caused by malposition of the inserted shunt. He also noted that we were bold enough to operate on 11 patients without an aortogram. I appreciated the comments of the discussants, including Dr. Alley. Dr. Cunningham, we have not used somatosensory evoked potentials. Our institution is a regional trauma center, and more than 80% of these patients undergo operation between 11:00 P.M. and 6:oO A.M., hours when many of the routine facilities of the hospital are unavailable. We have been looking at the intraluminal graft for application to these lesions. However, the tom aorta is much softer in the young patient than in the older patient with atherosclerosis, and we have no experience with its use in trauma. We avoid systemic heparinization with all of its inherent dangers. Dr. Wilson, the same surgeon who is inexperienced with the use of clamphepair is also inexperienced with the use of the shunt. We agree that problems occur when a surgeon is inexperienced in any area. Yes, there are more than 1,ooO patients reported in the literature who have had operations on the descending thoracic aorta. Many of these reports are single case studies or very small series. Other reports mix chronic, acute traumatic, atherosclerotic, dissecting, and luetic aneurysms. Many of these reports do not contain enough information to make a meaningful comparison. Our review comparisons include those reports we thought had enough meaningful data on chronic and acute traumatic aneurysms for analysis. Dr. Dieter, we are deeply concerned about hypothermia, and we begin warming the patient as much as possible by the time he or she reaches the emergency center by administering all crystalloid solutions at around 37.8"C. All blood that is administered is diluted with this warm crystalloid solution. We heat the cascade on the respirator. The theoretical spinal artery steal syndrome requires further research. Just as fracture of the first rib is a hallmark of severe trauma, so the time required to perform the repair is a hallmark of the extent of injury to the thoracic aorta. To focus on time alone as the contributing factor to complications is answer C on the Board examination-it is hue, hue and unrelated. Although there is a reported incidence of complications from the use of shunts, that is, postoperative bleeding and aneurysm at the cannulation site, I have no criticism for those who choose this more time-consuming and more complex technique. Neither technique is necessarily superior, and therefore neither should be condemned. Such territorial condemnation by wellmeaning thoracic surgeons has led to unnecessary and expensive litigation involving members of this society who use prudent judgment and good surgical technique. I trust that our future research efforts will be aimed at prevention, early diagnosis, and perioperative control of hypotension.