Management of Ascending Aortic

Transcription

1 Management of Ascending Aortic Aneurysm Complicating Coarctation of the Aorta Ramanathan Sampath, M.D., William N. O'Connor, M.D., Jacqueline A. Noonan, M.D., and Edward P. Todd, M.D., Ph.D. ABSTRACT Four patients with coarctation of the aorta complicated by an aneurysm of the ascending aorta are described. One patient, treated only medically, died suddenly. For the 3 patients who underwent operation, management was similar. Pharmacological control of blood pressure and repair of the aortic coarctation to achieve anatomical reduction in afterload (stage I) were followed after an interval of one to five weeks by surgical repair of the ascending aortic aneurysm (stage 11). Initial repair of the coarctation relieves proximal hypertension, thereby decreasing the chance of progressive dissection or rupture of the aneurysm. It also permits safe arterial cannulation for perfusion during correction of the aneurysm in the second stage. In patients not requiring valve replacement in stage 11, continued long-term follow-up for progression of aortic valvular disease appears to be necessary. Coarctation of the aorta is a common congenital cardiac anomaly, which now, in general, is repaired electively in the first 10 years of life. If repair is delayed, complications related to hypertension in the proximal aortic segment often develop, and include aneurysmal dilatation with dissection or rupture. The combination of coarctation of the aorta and ascending aortic aneurysm requiring operative intervention has received little attention in the literature. This report focuses attention on the challenging surgical problems that this combination represents. From the Department of Surgery, Division of Cardiothoracic Surgery, and the Departments of Pathology and Pediatrics, University of Kentucky Medical Center, Lexington, KY. Presented at the Twenty-eighth Annual Meeting of the Southern Thoracic Surgical Association, Palm Beach, FL, Nov 5-7, Address reprint requests to Dr. Todd, Division of Cardiothoracic Surgery, University of Kentucky Medical Center, 800 Rose St., Lexington, KY Material and Methods Since 1973, 4 patients with coarctation of the aorta and an aneurysm of the ascending aorta have been treated at the University of Kentucky Medical Center. During the same period, no examples of aneurysm of the aorta distal to a coarctation have been identified. The case histories of the 4 patients follow. Patient 1 A 12-year-old white boy had an episode of fainting while playing basketball at school and was taken to a local physician to whom he complained of headache and abdominal pain. The past history indicated that a diagnosis of coarctation of the aorta with aortic stenosis was made when the patient was 8 years old. A workup at that time included cardiac catheterization which demonstrated a 20 mm Hg gradient across the coarctation. Operation was not recommended, and in the ensuing 4 years the patient experienced only mild congestive heart failure, managed with digoxin and diuretics. On the latest admission, the physical examination showed a normal habitus. Cardiac examination revealed a quiet precordium with no palpable point of maximal impulse. A grade 2/6 systolic ejection murmur was audible along the left sternal border, and there was intermittent gallop rhythm. The right radial pulse was normal. The left radial pulse and both femoral pulses were weak. The remainder of the physical examination was unremarkable, and the child was afebrile. On the first hospital day, he had a spiking temperature to 38.9"C. The white blood cell count was 14,300/mm3 with 82% polycytes. Subacute bacterial endocarditis was suspected, but numerous blood cultures were negative. The patient remained in stable condition, but unexpectedly on the third hospital day, he experienced a cardiac arrest. Attempts at resuscitation were unsuccessful, and the patient died by The Society of Thoracic Surgeons

2 126 The Annals of Thoracic Surgery Vol 34 No 2 August 1982 Postmortem examination confirmed a moderate coarctation of the aorta just distal to the origin of the left subclavian artery. There was striking aneurysmal dilatation of the ascending thoracic aorta with localized dissection and transmural rupture arising in a 3.4 cm long, transverse intimal tear in the posterior wall of the aneurysm just 1 cm above the aortic valve. Three hundred fifty milliliters of freshly clotted blood distended the pericardial sac. Histological sections of the aorta proximal to the coarctation showed prominent cystic medial necrosis and nonspecific intimal fibrosis. In the region of recent rupture, there was an infarct of the wall of the aorta with a focal aortitis containing mononuclear cells and giant cells. The aortic valve was bicuspid, thickened, and mildly incompetent, and there was no evidence of bacterial endocarditis. The cause of death was aneurysmal rupture with cardiac tamponade. Patient 2 A 37-year-old white man had an 18-year history of hypertension treated medically by the family physician. Following the sudden onset of severe substernal chest pain, he was admitted to the hospital for a suspected myocardial infarction. However! during the first three hospital days there were no electrocardiographic or cardiac enzyme changes indicative of infarction. On the third hospital day, ventricular fibrillation and cardiac arrest occurred. The patient was successfully resuscitated. Following this, the cardiac enzymes were elevated, and he was hospitalized for three weeks on a regimen of antihypertensive medication and digoxin. The patient then was referred to the University of Kentucky Medical Center for further evaluation. On physical examination he had a normal habitus. The blood pressure in the upper extremities was 130/80 mm Hg, with no palpable pulses in the lower extremities. Cardiac examination revealed lateral displacement of the apical impulse, and on auscultation a grade 3/6 systolic ejection murmur was noted at the apex, along the left sternal border, and in the interscapular area. The chest roentgenogram showed cardiomegaly, bilateral notching of the ribs, and the 3 sign suggestive of coarctation of the aorta. On the electrocardiogram, the ef- Aortogram (Patient 2) in the left anterior oblique projection, demonstrating coarctation of the aorta and a large ascending aortic aneurysm from the aortic valve to just proximal to the origin of the innominate artery. fect of the digitalis was evident. An echocardiogram showed a greatly dilated aortic root. Cardiac catheterization was performed, and coarctation of the aorta distal to the left subclavian artery was noted. There was a pressure gradient of 50 mm Hg across it. Angiography (Figure) demonstrated a severe coarctation and a type I1 dissection of the proximal aorta that involved the origin of the left coronary artery. The initial surgical procedure (stage I) consisted of repair of the coarctation. Because of adequate collateral vessels, it was possible to clamp the aorta above and below the coarctation without using any form of bypass or shunt. The aorta was incised longitudinally, the coarctation membrane was resected, and a woven Dacron patch was placed over it. The postoperative period was uneventful, with good lower extremity pulses present at the time of discharge. One week later the patient underwent surgi-

3 127 Sampath et al: Aortic Aneurysm Complicating Coarctation cal repair of the ascending aortic aneurysm (stage 11) through a median sternotomy incision. He was placed on cardiopulmonary bypass with arterial cannulation in the femoral artery. A cross-clamp was applied proximal to the innominate artery. On inspection, the aneurysm was noted to be limited to the ascending aorta, and there was an intimal tear posteriorly and close to the left coronary ostium with intramural dissection that extended both proximally and distally. The aortic valve was bicuspid and scarred, with areas of calcification. Replacement of the ascending aorta and the aortic valve was accomplished using a 30 mm woven Dacron tubular graft attached to a 29 mm Bjork-Shiley aortic valve prosthesis. After the excess tissue of the aneurysm was removed, the wall was closed with sutures over the graft for hemostasis. The coronary arteries were implanted into the graft, with myocardial protection by means of moderate hypothermia and coronary perfusion. Pathological examination of the aortic valve showed it to be bicuspid, with stenosis and dystrophic calcification. The aneurysm from the ascending aorta showed evidence of healing of a recent dissection, with thrombus formation in the dissection channel. There was also cystic medial necrosis with intimal fibrosis. The patient did well postoperatively, and was discharged after ten days. Two and one-half years later he was admitted for dehiscence of the left coronary artery from the graft, where a pseudoaneurysm had formed. Successful repair was achieved using a segment of saphenous vein, which was anastomosed to the Dacron graft and the native left coronary artery. The postoperative course was uneventful, and currently the patient is asymptomatic 6 years following the initial operation. Patient 3 A 20-year-old white man with a vague history of recent chest tightness and palpitations was first noted to have a heart murmur by his family physician during treatment of an upper respiratory tract infection. He was referred to the University of Kentucky Medical Center for further evaluation. On physical examination the patient had a normal habitus. The blood pressure in both upper extremities was mm Hg, and pulses could not be palpated in the lower extremities. The apical cardiac impulse was displaced to the sixth intercostal space along the anterior axillary line. A grade 3/6 systolic ejection murmur was heard along the left sternal border and in the interscapular area. The chest roentgenogram showed cardiomegaly, a dilated ascending aorta, and bilateral notching of the ribs. The electrocardiogram demonstrated leftaxis deviation. At cardiac catheterization a complete coarctation of the descending thoracic aorta was detected. Angiography demonstrated a large aneurysm of the proximal aorta. The aortic valve was bicuspid, without a demonstrable gradient across it. There was no evidence of aortic or mitral insufficiency, and left ventricular function studies were within normal limits. The coarctation was repaired during stage I through a left thoracotomy incision. The aorta was incised vertically proximal and distal to the coarctation, and it was noted that no lumen existed through the coarctation. Then a 20 mm woven Dacron tubular graft was interposed, being anastomosed end-to-end to the aorta. This was achieved without using any form of bypass or shunt because there were adequate collaterals. The postoperative course was uneventful, and at the time of discharge, the patient s blood pressure was 110/70 mm Hg and he had good, palpable femoral pulses. He was readmitted five weeks after the initial operation for the repair of the ascending aortic aneurysm (stage 11). Operation was performed through a median sternotomy incision, using cardiopulmonary bypass with arterial cannulation in the transverse arch. A fusiform aneurysm limited to the ascending aorta was noted, with a transition to normal-appearing aorta in the transverse arch. The aneurysm was incised longitudinally. The aortic valve was bicuspid without much thickening or calcification. A 30 mm woven Dacron graft was interposed from the supracoronary position to just beneath the takeoff of the innominate artery. The excess tissue of the wall of the aneurysm was resected, and the remainder was closed over the graft. Pathological examination of the aneurysm wall showed numerous linear intimal tears, and microscopically there was mild intimal atherosclerosis with thinning and loss of elasticity

4 128 The Annals of Thoracic Surgery Vol 34 No 2 August 1982 in the media. Focal scarring was also noted in the media. At the time of writing, 3 years have passed since the second operation, and the patient is asymptomatic with a blood pressure of mm Hg. Patient 4 An 18-year-old asymptomatic black man was noted to have hypertension on routine preemployment physical examination. Hydrochlorothiazide therapy was begun, and he was referred for workup of the hypertension. On the day of admission, he complained of prolonged, severe, nonradiating headache. At cardiac catheterization there was severe coarctation of the aorta at the level of the left subclavian artery. The left subclavian artery appeared to fill late from the vertebral artery, and there was massive enlargement of the right mammary and right intercostal arteries with adequate filling of the descending aorta through collaterals. A large aneurysm of the ascending aorta was noted but there was no demonstrable aortic valve insufficiency. After pharmacological therapy brought the blood pressure under control, the patient underwent repair of the coarctation (stage I) through a left thoracotomy incision and using a woven Dacron patch. He did well postoperatively. Two weeks later, repair of the ascending aortic aneurysm (stage 11) was performed through a median sternotomy incision. The patient was placed on cardiopulmonary bypass, with arterial cannulation in the transverse aortic arch. The regurgitant fraction across the aortic valve was determined on bypass to be less than 20% of systemic flow. A large fusiform aneurysm of the ascending aorta was incised longitudinally, and on inspection the aortic valve was bicuspid without substantial fibrosis or calcification. The thin aneurysm wall had longitudinal intimal tears and scarring, and the right coronary artery was displaced superiorly away from the aortic valve approximately 3 cm. A 35 mm woven Dacron graft was anastomosed posteriorly in the supracoronary position just above the left coronary orifice, and then the suture line was brought down below the right coronary orifice adjacent to the anterior commissure. Subsequently, the right coronary artery was attached to the graft above the suture line. The distal graft was sutured to the aorta just beneath the innominate artery. The excess aneurysm wall was resected, and the remaining aorta was closed over the repair to assure adequate hemostasis. Pathological examination of the aneurysm wall revealed a marked loss of the elastic tissue with prominent cystic medial necrosis and focal scarring. The postoperative course was complicated by bleeding into the mediastinum that required reoperation. Following successful evacuation of a hematoma and control of bleeding, the patient did well and is asymptomatic and normotensive fifteen months postoperatively. Results The clinical data are summarized in the Table. Three patients 18 to 37 years old have undergone successful staged repair of both coarctation of the aorta and ascending aortic aneurysm. One other patient died before diagnosis or institution of therapy. The patients who underwent operation were managed similarly. Hypertension was controlled with oral medications including hydrochlorothiazide, a-methyldopa, and propranolol. Acute elevations in blood pressure were managed with nitroprusside. The coarctation was repaired at the first stage of a planned two-stage repair. During the initial surgical procedure and postoperatively, all patients required nitroprusside for periods of up to several days to control acute elevations in pressure greater than 130 mm Hg systolic and 90 mm Hg diastolic. Second-stage repair of the ascending aortic aneurysm in 3 patients and of the aortic valve in 1 patient was accomplished between one and five weeks after the first-stage coarctation repair. The second-stage repair was done on cardiopulmonary bypass in all 3 patients who underwent operation, utilizing coronary perfusion for myocardial protection. The arterial return from the oxygenator was to the transverse aorta in 2 and to the femoral artery in 1. The

5 129 Sampath et al: Aortic Aneurysm Complicating Coarctation Summary of Data on 4 Patients with Coarctation with Aneurysm of the Proximal Aorta Surgical Patient No., Repair Age (yr), Clinical Coarctation: Interval Aneurysm: Current Sex Presentation Anatomical Findings Stage I (wk) Stage I1 Status 1. 12, M Known coarctation; sudden syncopal episode 2. 37, M Long-standing hypertension; sudden substernal chest pain 3. 20, M Murmur discovered on routine physical examination 4. 18, M Hypertension noted on preemployment physical examination Coarctation distal to with cystic medial necrosis; bicuspid aortic valve; dissection with rupture Coarctation distal to with dissection and cystic medial necrosis; stenotic bicuspid aortic valve Coarctation distal to with healed intimal tears and medial scarring; bicuspid aortic valve Coarctation involving with healed intimal tears, scarring, and cystic medial necrosis; bicuspid aortic valve None Dacron patch Tubular Dacron graft Dacron patch... None 1 Composite tubular Dacron graft and valve replacement; coronary reimplantation 5 Tubular Dacron graft 2 Tubular Dacron graft; coronary reimplantation Died 3 days after admission Alive and well 5% years postop Alive and well 21/2 years postop Alive and well 9 months postop LSA = left subclavian artery. ascending aorta and aortic valve were replaced in Patient 2, and the coronary arteries were reimplanted into the Dacron graft. In Patients 3 and 4 the native valve was retained, and in Patient 3, the graft was sewn into the supracoronary aorta proximally. In Patient 4, the right coronary orifice was displaced so far from the aortic valve that the graft was sewn between the valve and the right coronary artery, and the coronary artery was reimplanted into the graft to minimize the amount of abnormal aorta left in continuity with the native valve. All 3 patients survived and have been followed for from fifteen months to 6 years. Two required reoperation, one immediately after operation for excessive postoperative bleeding and one 2l/2 years after the initial procedure for a pseudoaneurysm, which developed where the left coronary artery was attached to the graft. Comment Coarctation of the descending aorta is a common congenital cardiovascular anomaly, occurring in one of 12,000 live births [l]. Studies of the natural history of this disease before the introduction of surgical management [2-41 indicate that of those patients who survived the first 1 to 2 years of life, the mean life expectancy was only 34 years [3]. The majority of these patients died of direct complications of coarctation, namely, aneurysmal dissection or rupture, bacterial endocarditis or aortitis, congestive heart failure, or cerebrovascular accidents [41. Reviewing the world literature up to 1960, Skandalakis and colleagues [5] found twentytwo aneurysms of the aorta in 106 patients with coarctation. The reported incidence of aneurysm associated with coarctation dropped from 21% in the presurgical era to 5% in the

6 130 The Annals of Thoracic Surgery Vol 34 No 2 August 1982 period after surgical therapy was available. It is interesting that they found 32% of the aneurysms were proximal to the coarctation, 51% were distal to it, and 17% did not involve the aorta. During the period of the study presented here, all four aneurysms involved the proximal aorta. Dilatation frequently was observed in the distal aorta past the area of stenosis, but this was never considered to be truly pathologically aneurysmal. None of the patients in this series had Marfan s syndrome, but 3 of the 4 had cystic medial necrosis. The mechanism whereby coarctation predisposes to aneurysm formation is incompletely understood. It is postulated that aneurysmal dilatation is (1) the result of long-standing hypertension and gradual weakening of the arterial wall, (2) the result of endocarditis or aortitis which, in turn, weakens the aortic wall, or (3) a congenital weakness of the arterial wall of patients with coarctation. That only a minority (32%) of aneurysms occurred in an aorta proximal to the coarctation, where the pressure is higher [5], and that the reported incidence of mycotic origin of aneurysms is low [61, suggest that, in the majority of cases, an intrinsic factor in the wall of the aorta underlies the formation of aneurysms. Histologically, cystic medial necrosis is commonly observed in sections of the aorta proximal to the site of coarctation. Here it may represent a nonspecific response to hemodynamic stress in the aortic media [6, 71. However, the fact that similar histological findings occur in arteries under less hernodynamic stress, for example, the pulmonary artery, has caused others to suggest that the etiology of cystic medial necrosis may be congenital [7]. Irrespective of the etiology, a spectrum of significant histopathological changes commonly is present in the proximal aorta. Presumably, these changes predispose to weakness of the media with induration and inflexibility of the intima and lead to aneurysm formation and then dissection, or rupture in patients with coarctation. Management of dissection of the ascending aorta in the presence of severe aortic coarctation poses problems. Initial pharmacological and then later more permanent anatomical reduction in afterload by resection of the aortic coarctation seem to be the logical initial management [7]. Repair of coarctation first relieves proximal hypertension, thereby decreasing the chance of progressive dissection or rupture. Furthermore, this permits safe perfusion during correction of the dissecting aneurysm in the second stage, either through the femoral artery or through the aortic arch. Two patients in this series were perfused through the transverse aorta and one through the femoral artery without evidence of perfusion inadequacies. The potential for further dissection, rupture, or both of the aorta before, during, and after repair of the coarctation has been minimized by careful control of blood pressure with hydrochlorothiazide, a-methyldopa, and propranolol. Acute elevations in pressure are controlled with nitroprusside. Typically, nitroprusside has been used to maintain systolic pressure less than 130 mm Hg and diastolic pressure less than 90 mm Hg. Utilizing this approach, no complications referable to the ascending aortic aneurysm have been observed while the patient was waiting for repair of the aneurysm at the second stage. Because of the recognized occurrence of aortic valve disease late in the postoperative course [8], management of the aortic valve can be problematic. In 1 patient in this series, the choice was clear. The valve was bicuspid and stenotic with evident calcification. Valve replacement and repair of the ascending aorta in continuity was necessary. In the other 2 patients who had operation, the valves were bicuspid and both had mild valvular insufficiency. There was no evidence of stenosis with hemodynamic importance, or valvular thickening or calcification. Neither valve was replaced. It was hoped that repair of the coarctation and control of hypertension would minimize progression of the aortic valve insufficiency. Both patients continued to have murmurs indicative of aortic insufficiency at follow-up, but neither has demonstrated any evidence of congestive failure or further ventricular enlargement. To date, this approach at least has delayed aortic valve replacement, but clearly, in this circumstance, the natural history of the aortic disease is unknown. Therefore, close follow-up is indicated.

7 131 Sampath et al: Aortic Aneurysm Complicating Coarctation References 1. Schneider JA, Rheuban KS, Crosby IK: Rupture of postcoarctation mycotic aneurysms of the aorta. Ann Thorac Surg 27:185, Abbott ME: Coarctation of the aorta of the adult type, Part 2: A statistical study and historical retrospect of 200 recorded cases, with autopsy, of stenosis or obliteration of the descending arch in subjects above the age of two years. Am Heart J 3:574, Campbell M: Natural history of coarctation of the aorta. Br Heart J 32:633, Reifenstein GH, Levine SA, Gross RE: coarctation of the aorta. Am Heart J 33:146, Skandalakis JE, Edwards BF, Gray SW, et al: Coarctation of the aorta with aneurysm. Int Abstr Surg 111: , Edwards BF, Gray SW, Hopkins WA, et al: Coarctation of the aorta complicated by the formation of aneurysm. Surgery 52: , Lawson RA, Fenn A: Dissection of an aneurysmal ascending aorta in association with coarctation of the aorta. Thorax 34:5, Maron BJ: Coarctation of the aorta in the adult. Cardiovasc Clin 10: , 1979