Asian Cardiovasc Thorac Ann 1999;7:186-189
© 1999 Asia Publishing EXchange Pte Ltd
Aortic Root Replacement with Composite Graft: Experience in 95 Patients
Sun Li Zhong, MD,
Ren Jie, MD,
Wu Qing Yu, MD,
Chang Qian, MD,
Yang Tian Yu, MD,
Zhao Xiao Qin, MD,
Zhu Jun Ming, MD,
Liu Yong Ming, MD
Department of Cardiac Surgery
Cardiovascular Institute and Fu Wai Hospital
Beijing, People's Republic of China
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For reprint information contact: Sun Li Zhong, MD Tel: 86 10 6831 4466 Ext. 8187 Fax: 86 10 6831 3012 email: slzh{at}public.bta.net.cn Department of Cardiac Surgery, Cardiovascular Institute and Fu Wai Hospital, CAMS and PUMC, 167 Beilishi Road, Beijing 100037, People's Republic of China.
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Abstract
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Between January 1994 and June 1998, 95 patients with a mean age of 40.6 years (range, 23 to 69 years) underwent aortic root replacement with composite grafts. The operations were performed under hypothermia and cardiopulmonary bypass. In dissecting aortic aneurysm or aneurysms involving the aortic arch, selective cerebral perfusion via the right subclavian artery was employed, with additional femoral arterial cannulation if necessary. Combined procedures included partial arch replacement (6), elephant trunk technique (2), and mitral valve replacement (2). The mean duration of aortic crossclamping was 74.3 ± 17.9 min (42 to 133 min) and the mean duration of cardiopulmonary bypass was 117.8 ± 28.6 min (60 to 232 min). The hospital mortality was 1.1% (1 patient) and there was one late death. Complications comprised reexploration for bleeding (2), pericardial effusion (2), cerebral infarction (1), pleural effusion (1), and pneumothorax (1). Blood transfusion was not needed in 8 patients. Hemorrhage was the most dangerous complication. Suitable operative methods and improved techniques are the keys to successful aortic root replacement.
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Introduction
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Replacement of the aortic root is the most radical mode of treating an aneurysm of the proximal aorta and aortic valve regurgitation. In 1968, Bentall and DeBono1 described a technique for replacing an aneurysmatic ascending aorta and incompetent aortic valve with a composite graft. Since then, some modifications of this procedure have been made and surgical results have improved remarkably. From January 1994 to June 1998, we performed aortic root replacement in 95 patients with satisfactory results. This report summarizes our experience in terms of operative indications, methods, and surgical techniques.
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Patients and Methods
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Of the 95 consecutive patients who underwent aortic root replacement in our institution, 5 were treated on an emergency basis. The majority (80 patients, 84%) were male and ages ranged from 23 to 69 years with a mean age of 40.6 ± 10.4 years (Table 1
). The diameter of the aneurysm measured by direct inspection, varied from 4.5 to 10 cm (mean, 7.3 ± 1.4 cm). Symptoms included chest pain, palpitations, and dyspnea on exertion. Eight patients were asymptomatic and presented only with a murmur. Physical examination showed cardiac enlargement, a blowing diastolic aortic murmur, wide pulse pressure, and water-hammer pulse. Preoperative echocardiography, computed tomography, and magnetic resonance imaging indicated the type and size of the aneurysm, pathological changes of the aortic valve, and associated diseases.
Among the 95 patients, 53 had pure aortic root aneurysms without dissection, 26 suffered from DeBakey type I aortic dissection, and the remaining 16 were diagnosed as DeBakey II aortic dissection. Aortic valve regurgitation was involved in the disease process in all cases, combined with mitral insufficiency in 2 cases. Other concomitant lesions included DeBakey type III aortic dissection in 2 cases and one case each of descending thoracic aortic aneurysm, abdominal aortic aneurysm, abdominal aortic aneurysm combined with left iliac aneurysm, ruptured aneurysm of the sinus of Valsalva, and ventricular septal defect. Clinically obvious stigmata of Marfan syndrome were noted in 54 patients; additional causes of aneurysms are listed in Table 2. The indications for replacement of the aortic root in patients with nondissecting and chronic dissecting aneurysm were based primarily on the diameter of the aortic root with 5 cm considered the critical size.
All patients were operated through a midline sternotomy incision. Upon incision of the aorta, it was decided whether the coronary ostia should stay in place or be excised from the aortic wall in the form of Carrel buttons. In patients with anatomically normal aortic leaflets, valve reconstruc-tion was an alterative option to valve replacement. If the valve could not be repaired, the valve cusps were excised and the aortic root was replaced by a valved conduit that was anchored to the annulus by a running 3/0 poly-propylene suture or five 6 x 14 mattress sutures in each sinus. Then, the valved conduit was pushed down and the sutures were tautened and tied. Fenestrations of approximately 1 to l.5 cm were made by thermal cautery in the side wall of the graft, corresponding to the ostium of each coronary artery. Sometimes the ostia were anastomosed to the graft with continuous 4/0 poly-propylene sutures (button technique). More commonly, both coronary ostia were sewn directly to the holes using a running 4/0 polypropylene suture when the aortic wall appeared friable or dissecting. This technique was used in 88 patients (93%). Finally, the distal ascending aorta was anastomosed to the composite graft with 3/0 polypropylene suture.
When part or all of the aortic arch required replacement, the brachiocephalic vessels were crossclamped after aortic root replacement and the aortic arch was replaced during hypothermic circulatory arrest and selective cerebral perfusion via the right subclavian artery. Several methods were used for distal graft-to-aorta anastomosis. For dissection involving the ascending aorta and arch, the procedure consisted of partial or total arch replacement and the graft was anastomosed to the normal distal aorta. Surgical treatment for dissection in the aortic arch and distal aorta with a small false lumen and no secondary tears in ascending aorta consisted of resection of the descending thoracic aorta proximal to the origin of the dissection (usually at, or just below, the origin of the innominate artery). The separated layers of the aorta were approximated between an outer and inner strip of Teflon felt with a running polypropylene suture, followed by end-to-end anastomoses to the graft. If the dissecting aneurysm involved the aortic arch and distal aorta with a large false lumen and secondary tears in the ascending aorta or if the ostia of vessels to important organs were in the false lumen, the distal ascending aorta and the graft were anastomosed directly using pads with both true and false lumens connected to the graft to provide blood to both lumens.
In one patient with extensive aneurysmal lesions and another with a DeBakey type I dissecting aneurysm, both aortic root replacement and the elephant trunk technique were used. Routine aortic root replacement was performed under moderately hypothermic cardiopulmonary bypass, the aorta was then transected just beyond the left subclavian artery during selective cerebral perfusion via the right subclavian artery. A graft was selected for insertion into the true lumen and anastomosed to the descending aorta with a 3/0 polypropylene running suture, leaving a segment of the distal tubular graft in the descending thoracic aorta, which was available for the second stage of the operation. The proximal graft was anastomosed to the aortic arch graft with a 3/0 polypropylene suture and the aortic arch was replaced as described above.
Composite graft replacement according to the Bentall method or its variants was performed in 93 patients and the other two underwent a valve-sparing operation. Six patients underwent subtotal arch replacement. Con-comitant mitral valve replacement was carried out in 2 patients. Other concomitant procedures included resection of an abdominal aortic aneurysm and left iliac aneurysm and replacement with grafts in one patient and repair of a ruptured aneurysm of the sinus of Valsalva in another.
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Results
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Standard hypothermic cardiopulmonary bypass was employed in 54 patients (57%) including all who had pure aortic root replacement. The mean aortic crossclamp time in these 54 patients was 70 ± 17.1 min (range, 42 to 133 min) and the mean duration of extracorporeal circulation was 103.7 ± 28.6 min (range, 60 to 215 min). Deep hypothermia and circulatory arrest was used in 10 cases (10.5%) with a mean circulatory arrest time of 14.7 ± 5.6 min (range, 1 to 28 min). Deep hypothermia and circulatory arrest with selective cerebral perfusion via the right subclavian artery was used in 31 cases (32.6%) with a mean selective cerebral perfusion time of 14.7 ± 5.6 min (range, 2 to 23 min). Among all 95 patients, the mean aortic crossclamp time was 74.3 ± 17.9 min (range, 42 to 133 min) and the mean duration of extracorporeal circulation was 117.8 ± 32.7 min (range, 60 to 232 min).
Hospital mortality was 1.1% (1 patient). This patient had an acute DeBakey type I dissecting aneurysm combined with aortic regurgitation and underwent an emergency Bentall procedure. The patient suffered superior mesenteric artery ischemia and intestinal necrosis postoperatively, and died on the 44th postoperative day due to toxic shock. Other early complications involved: hemorrhage requiring reexploration in 2 patients, pericardial effusion in 2, as well as cerebral infarction, pleural effusion, and pneumothorax, in one patient each. These patients with complications recovered with appropriate treatment. The mean transfusion volume was 1214 ± 1139.2 mL (range, 0 to 9800 mL); 8 patients needed no blood transfusion. Mean postoperative hospital stay was 16.8 ± 6.4 days (range, 8 to 41 days). The two patients who underwent a combined Bentall procedure and elephant trunk technique had satisfactory clinical results.
The follow-up was 65.8% complete. During a mean follow-up of 7.3 ± 7.6 months (range, 2 weeks to 36 months), one patient died from lower-limb embolism and renal dysfunction at 3 months postoperatively. Of the patients who could be followed up, 51 were in New York Heart Association functional classes I and II and two were in class III; they were treated medically with favorable results. Echocardiography showed all prostheses functioned well and the aortic grafts were unobstructed. The preoperative and postoperative mean left ventricular end-diastolic diameters were significantly different (69.1 ± 9.4 mm versus 52.9 ± 9.1 mm; p < 0.001).
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Discussion
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Aortic root aneurysm is believed to be one of the most common potentially fatal aortic diseases. Once begun, aneurysm expansion and rupture are usually inevitable. Medical treatment has limited effect and aortic root replacement is the only alternative.
Currently, the hospital mortality rate reported for the Bentall procedure is approximately 6.3% (range, 4.8% to 9.2%).2 In our experience of 95 consecutive aortic root replacement operations since January 1994, the hospital mortality rate was 1.1% and the complication rate was 7.4%.
According to Gott and colleagues3 in a clinical study of Marfan syndrome patients, the possibility of dissection is reduced if early surgery is carried out. Patients without symptoms should be offered surgery if the diameter of the aneurysm is greater than 5 cm, in view of the excellent early and late results. Available data suggest that in asymptomatic patients, the larger the aneurysm and the more rapid its increase in size, the more likely rupture will occur and a diameter of 5 cm is the point at which operative repair should be considered. In our series, there were 8 patients who had no symptoms except for a heart murmur. The mean diameter of the aneurysm of these patients was 6.7 cm. It has been suggested that the operative indications should be stricter in patients with a family history of aortic dissection.3 The natural history of acute dissecting aneurysms is always severe. It has been estimated that 60% to 90% of these patients die within the first week, mostly because of rupture of the ascending aorta.4 Once a diagnosis of acute aortic root dissecting aneurysm is made, the patient should undergo surgery as soon as possible.
Operative technique depends on the location and the extent of the aneurysm and the presence or absence of aortic dissection. In pure aortic root aneurysm, cardio-pulmonary bypass was initiated with cannulation of the ascending aorta or a femoral artery and the right atrium, using a 2-stage catheter. Some authors have recommended femoral artery cannulation because of the risks associated with redo sternotomy.5 Venous return was established by cannulation of the superior and inferior venae cavae when the patient had mitral disease. A sump drain was placed into the right superior pulmonary vein or the main pulmonary artery. The normal aorta distal to the aneurysm was crossclamped and antegrade crystalloid potassium cardioplegia was administered directly into the coronary ostia.
According to the anatomical characteristics of the right subclavian, innominate, and basilar arteries, we used selective cerebral perfusion via the right subclavian artery in patients with a dissecting aneurysm or an aneurysm involving the aortic arch; femoral arterial cannulation was used simultaneously if necessary. The ascending aorta and sometimes also the brachiocephalic vessels were crossclamped according to intraoperative needs. The advantages of using the right subclavian artery are that proximal segments of the brachiocephalic vessels can be clamped and the brain is selectively perfused in an antegrade (physiological) fashion. In addition, the diameter of the right subclavian artery is adequate for perfusion and the site of incision is in the chest, for easier operative management. We used this method in more than 60 aortic arch operations; the longest cerebral perfusion time was 80 minutes. All patients were awake on the evening of the operative day without the use of mannitol and gluco-corticoids and there were no neurological or other complications. However, this technique is slightly more difficult than other methods of brain and spinal cord protection.
Aortic root aneurysm was combined with mitral valve disease in two of our patients. Marfan syndrome patients have a much higher incidence of mitral valve dysfunction.6 Most of the mitral pathological changes develop progressively so the mitral valve should be managed aggressively at operation. Mitral valve surgery is necessary even when mild to moderate regurgitation is present, to prevent reoperation soon after aortic root replacement because of mitral valve dysfunction. Most of these patients undergo mitral valve repair and some need valve replacement. Cannulation of the superior and inferior venae cavae was necessary. Mitral valve surgery was performed through the atrial septum before undertaking aortic root replacement.
Hemorrhage is the most serious complication and the main cause of operative death. The key to successful aortic root replacement may be the achievement of perfect hemostasis. On the basis of our experience, we advocate selection of the most appropriate basic method of exposing the operative field to ensure enough time for the operation. This is a key factor in preventing hemorrhage. Use of a presealed graft can reduce the incidence of postoperative bleeding from the graft. Browdie7 reported that presealed composite grafts with porous sewing cuffs may be a contributory factor to diffuse aortic root hemorrhage. Precise anastomosis and refined manipulation are warranted for a successful operation. Once postoperative hemorrhage occurs, a shunt between the perigraft space and the right atrium is deemed necessary for controlling anastomotic leakage. This method of hemostasis was used in 20 patients in our series, with satisfactory results. As seen during follow-up, the shunt closed soon after hemostasis and had little effect on hemodynamic status. Hemorrhage has been a rare complication in recent years and operative transfusion volumes have been greatly reduced. Eight of our patients needed no blood transfusion.
Brain and spinal cord protection is crucial during aortic root replacement which is a complicated procedure with a long operative time. Some manipulations need circu-latory arrest with the attendant risk of postoperative neurologic complications. Selective cerebral perfusion via the right subclavian artery gave satisfactory brain protection in this study. The two patients who underwent a concomitant Bentall procedure and elephant trunk technique had separate femoral arterial perfusion and selective cerebral perfusion. Selective cerebral perfusion via the right subclavian artery was used during anastomosis of the distal part of the graft and the descending aorta, the graft was clamped when the anastomosis was completed. Then the graft was anastomosed to the aortic arch graft, with femoral and subclavian arterial perfusion. This method maintains cerebral perfusion, reduces spinal cord ischemic time, and prevents postoperative neurological complications.
Recently, operative mortality associated with the Bentall procedure has been gradually reduced. According to some reports, operative risk factors include poor preoperative New York Heart Association functional class, non-Marfan status, the presence of aortic dissection, male gender, age above 50 years, and reoperation for hemorrhage. We believe that hemorrhage is the most serious risk. We emphasize that selection of proper basic methods and improved operative techniques are the key factors for a successful operation.
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References
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Bentall H, DeBono A. A technique for complete re-placement of the ascending aorta. Thorax 1968;23:338–9.[Abstract/Free Full Text]
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Mingke D, Dresler C, Stone CD, Borst HG. Composite graft replacement of the aortic root in 335 patients with aneurysm or dissection. Thorac Cardiovasc Surg 1998;46:12–9.[Medline]
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Gott VL, Gillinov AM, Pyeritz RE, Cameron DE, Reitz BA, Greene PS, et al. Aortic root replacement. Risk factor analysis of a seventeen-year experience with 270 patients. J Thorac Cardiovasc Surg 1995;109:536–45.[Abstract/Free Full Text]
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Pressler V, McNamara JJ. Thoracic aortic aneurysm: natural history and treatment. J Thorac Cardiovasc Surg 1980;79:489–98.[Medline]
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Hahn C, Tam SKC, Vlahakes GJ, Hilgenberg AD, Akins CW, Buckley MJ. Repeat aortic root replacemant. Ann Thorac Surg 1998;66:88–91.[Abstract/Free Full Text]
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Pyeritz RE, Wappel MA. Mitral valve dysfunction in the Marfan syndrome. Clinical and echocardiographic study of prevalence and natural history. Am J Med 1983;74:797–807.[Medline]
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Browdie DA. Aortic root hemorrhage and presealed composite grafts with porous sewing cuffs. Ann Thorac Surg 1998;66:609–10.[Free Full Text]
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Abstract
Introduction
