Asian Cardiovasc Thorac Ann 2006;14:462-466
© 2006 Asia Publishing EXchange Ltd
Mortality and Morbidity After Aortic Root Replacement: 10-Year Experience
Alireza A Ghavidel, MD,
Mohammad B Tabatabaei, MD,
Mohammad A Yousefnia, MD,
Gholam-Reza Omrani, MD,
Nader Givtaj, MD,
Kamal Raesi, MD
Rajaee Heart Centre, Iran University of Medical Sciences, Tehran, Iran
For reprint information contact: Alireza A Ghavidel, MD Tel: 98 21 264 2894 Fax: 98 21 204 2037 Email: aaghavidel{at}yahoo.com, Rajaee Heart Centre, Vali-e-Asr Avenue, Tehran, Iran.
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ABSTRACT
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Aortic root reconstruction remains a challenging surgical procedure. This retrospective study was carried out to evaluate the early and long-term outcomes of aortic root replacement over a 10-year period. There were 83 patients with a mean age of 43.2 ± 14 years (range, 10 to 78 years). Type A aortic dissection and Marfan syndrome were found in 28% and 24%, respectively. The most common technique used for repair of this condition was the Bentall operation. The mean duration of follow-up was 29.6 ± 28 months, ranging from 1 to 120 months. Hospital (30-day) mortality was 13.3% (11 patients). Two patients died during the late follow-up. The mortality was significantly higher in patients presenting with cardiogenic shock, those with long cardiopulmonary bypass and crossclamp times, and the group who had concomitant coronary artery bypass grafting. Emergency operation was not a significant risk factor for early death in our patients. The most common complications were bleeding and neurological sequelae. Aortic root replacement can be achieved with acceptable mortality and morbidity in a high-risk group of patients. Improvements in the outcome may be achieved by faster transport of patients in cardiogenic shock, and by reducing the cardiopulmonary bypass and crossclamp times.
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INTRODUCTION
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Aortic root replacement remains a challenging surgical procedure. Aortic dissection and aneurysm of the ascending aorta are the two major indications for this procedure. The prevalence of thoracic aortic aneurysm is difficult to determine because of under-reporting of these aneurysms in mortality statistics.1 Aortic aneurysms are the 13th leading cause of death in the United States, with an incidence of 5.9 cases per 100,000 person-years, and replacement of the ascending aorta accounts for the majority of thoracic aortic procedures.2 Surgery for acute aortic dissection has been developed in the last 70 years.1 Although several surgical methods have been introduced, their mortality and morbidity may range from 9% to 31%.1,2 Over the last decade, several conservative methods have been used in patients with a normal aortic valves: aneurysm binding, plication, and sub-coronary aortic replacement. However, in cases where the aortic valve, annulus, or sinuses of Valsalva are involved, a more definitive procedure must be carried out. The aim of this study was to evaluate the results of different techniques of aortic root replacement and identify factors affecting the early mortality and morbidity.
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PATIENTS AND METHODS
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Between March 1993 and April 2003, 83 patients underwent aortic root replacement at the Rajaee Heart Centre. Data were collected retrospectively from the medical and operative records. All patients were followed up at the cardiology and cardiac surgery clinics, with the first visit made one month after the operation and then at 6-monthly intervals. History, physical examination, electrocardiography, chest radiography, and transthoracic echocardiography were carried out in all patients. Transesophageal echocardiography and computed tomography, or an exercise tolerance test, were performed as necessary. The follow-up period ranged from 1 to 120 months, with a mean of 29.6 ± 28 months. Table 1
lists the preoperative characteristics of our patients. Acute type A aortic dissection was seen in 23 patients (28%). These patients underwent aortic root replacement as the aortic valve was deemed irreparable; they accounted for 34% of all patients referred to our center with acute type A aortic dissection.
A median sternotomy was performed under general anesthesia in all patients. The ascending aorta was cannulated most frequently. Femoral arterial cannulation was carried out in cases of aortic dissection, arch involvement, and in most re-operations. Venous cannulation was achieved using a two-stage venous cannula via the right atrium, except in a few patients in whom the femoral vein was cannulated due to emergency status. After establishment of cardiopulmonary bypass (CPB), cold blood or crystalloid cardioplegia and moderate hypothermia were used. Deep hypothermia was induced in only 2 patients with arch involvement. After a longitudinal aortotomy, the valve leaflets were excised if abnormal and if repair was judged to be impossible. Table 2 shows the operative details and reveals that the majority of patients were operated on using the Bentall procedure. A composite graft of appropriate size was inserted using interrupted 2/0 Ethibond (Ethicon, Somerville, NJ, USA) pledgeted sutures or continuous 2/0 polypropylene, according to the surgeon’s preference. Most patients had a classic Bentall procedure using side-to-side anastomosis without excision of the coronary ostia. The distal aortic anastomosis was performed using running 3/0 or 4/0 polypropylene sutures. Control of bleeding from the suture lines was achieved in some cases by application of fibrin glue or by wrapping the newly formed ascending aorta with another Dacron or pericardial patch. One surgeon preferred to preserve the native aortic wall and in cases of excessive bleeding, wrapped this around the composite graft (inclusion method). An artificial fistula was then created with a 6 or 8 mm Dacron or Gore-Tex tube from the false lumen (between the graft and the native aortic wall) to the right atrial appendage. This iatrogenic left-to-right shunt did not have any significant hemodynamic effect and closed spontaneously after a few days. De-airing, weaning from CPB, decannulation and closure of the sternum were carried out as usual.
Statistical analysis was performed with SPSS version 1 software (SPSS, Inc., Chicago, IL, USA). Continuous variables were described by the mean ± standard deviation. The Student t test was used to compare continuous variables. The Mann-Whitney rank sum test was used to compare medians where a normality test failed. Noncontinuous variables were compared using the chi-squared test or Fisher’s exact test, as appropriate. A p value of less than 0.05 was considered to be statistically significant.
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RESULTS
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The hospital (30-day) mortality in this series was 13.3% (11 patients). The mortality rate was 11.5% for patients with Marfan syndrome, and 27.3% for those with acute aortic dissection. Mortality rates for emergency and elective operations were 27.6% and 14.2%, respectively, which was not statistically significant. Table 3 shows the independent predictors of hospital mortality: long CPB and aortic crossclamp times, cardiogenic shock, and concomitant coronary artery bypass grafting were significant factors in early mortality. The causes of hospital mortality are listed in Table 4; cardiac failure was the most common cause of death.
Two patients died late in the follow-up. One was a 78-year-old man who died of myocardial infarction 2 years after his operation. The other was a 49-year-old man with Marfan syndrome who died 2 months postoperatively of an unknown cause.
Table 5 shows the incidence of postoperative complications. Bleeding was the most common complication, occurring in 20 patients. In 4 of these, correction of coagulation factors resulted in control of the bleeding; however, 16 patients required exploration, and 2 died due to failure to control bleeding.
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DISCUSSION
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Contemporary surgical series on ascending aortic aneurysm, using modern grafting techniques and methods of cerebral and myocardial protection, report hospital mortality rates of 1.7% to 17.1%.1–4 Although comparisons of outcome are difficult because of the heterogenicity of patients and differences in the proportions of aortic dissection, emergency operations, re-operations, and arch replacement, operative mortality for repair of acute aortic dissection has fallen since the original 40% mortality reported in 1965.1,2 Improved intensive care for these patients, earlier recognition of aortic dissection by advanced imaging modalities, improvements in the safety of CPB, and development of hemostatic vascular graft materials and other hemostatic agents are likely to be responsible for the improved surgical outcomes in these patients.1,2,5 The introduction of aortic root replacement with a composite graft, according to the classic and modified Bentall techniques, has improved the postoperative outcome significantly and provided satisfactory early and long-term results, especially in patients with aortic dissection.2,6 An aortic homograft or pulmonary autograft are alternatives to a composite graft in aortic root replacement. Although the advantages of human tissues over synthetic materials are obvious, availability and durability of such tissues limits frequent use, and placement is technically more demanding.
Complete aortic root replacement with a composite graft has a number of advantages: all diseased aortic tissue is eliminated, and the operation is conceptually simple and feasible.5,7 Furthermore, these composite grafts are available on demand in every cardiac center, and they are made in different sizes. The main disadvantage of such a technique may be the development of a false aneurysm at the site of coronary artery implantation, due to coronary artery detachment from the synthetic graft, or obstruction and thrombosis when the Carbol method is employed. False aneurysms were reported on transthoracic echocardiography in 2 of our patients; the inclusion technique was employed in both. However, on further evaluation, surgical intervention was not necessary. Currently, we do not perform the classic Bentall operation because of the higher incidence of false aneurysm formation and other complications, and hence Carbol bypass is no longer carried out.
We used a modification of the classic Bentall operation in 7 patients, creating a fistula from the peri-graft space to the right atrium using a Gore-Tex tube graft. This served to reduce the amount of bleeding and may have decreased the incidence of late false aneurysm formation. We recommend this procedure in selected cases, especially in dissecting aortic aneurysm and Marfan syndrome, as achievement of good hemostasis is a major problem in such patients. Usually, this artificial fistula obliterates after a few days and does not result in any complications. Initially we believed that in patients undergoing aortic root replacement by the classic Bentall technique, wrapping the native aortic wall around the graft might reduce tension between the graft and coronary arteries and also prevent catastrophic hemorrhagic complications. However, we did not find any statistical difference between the inclusion method and the button technique with en-bloc resection.
The early mortality in this series was higher than some of the recently reported studies.3–6,8–17 Moreover, the incidence of acute aortic dissection in our patients (28%) is high compared to other reports. Westaby and colleagues3 had 5.7% mortality in a group of patients with no aortic dissection. However, Fukada and colleagues15 had an excellent result in patients with Marfan syndrome, reporting mortality of 7.9%, while more than 30% of these patients had aortic dissection. The mortality rate in patients with aortic dissection or those having an emergency operation was almost twice the mortality rate of elective surgery (27% vs. 14%). The higher mortality rate in patients with aortic dissection is closely related to the complex type of aortic disease leading to a more difficult surgical procedure, poor preoperative hemodynamics, emergency status, and the presence of acute myocardial infarction due to dissected coronary sinuses. Several factors have been cited as predictors of early death after aortic root replacement. These include emergency operation, older age (> 65 years), the presence of aortic dissection, concomitant coronary artery bypass grafting, preoperative functional class, left ventricular ejection fraction < 35%, long CPB time, and arch replacement.2,5,16,18,19 We found that cardiogenic shock, concomitant coronary artery bypass grafting, prolonged CPB time (> 180 min) and crossclamp time (> 120 min) were strong predictors of early mortality. Late mortality in our patients was 2.4%, and because of the small number, we could not identify predictors of late death. The actuarial survival at 5 years was 82.1% in our patients.
The incidences of bleeding and neurologic complications were higher in our study compared to others, this could be due to the higher incidence of dissection in our patients. Other postoperative complications were similar to previous reports.1,3,5,10,12 Factors that adversely affect the development of postoperative morbidity include long CPB and aortic crossclamp times, left ventricular ejection fraction < 35%, aortic dissection, and concomitant coronary artery bypass grafting. We did not encounter valve-related complications such as prosthetic valve malfunction, thromboembolism, or endocarditis.
Aortic root replacement using a composite graft may be performed with acceptable results. Using the classic Bentall technique and inclusion method does not infer any advantage over en-bloc resection and the button technique of coronary transfer. The mortality in different series is closely related to the proportion of patients with acute aortic dissection, but the long-term survival after this procedure is excellent.
Presented at the 12th Annual Meeting of the Asian Society for Cardiovascular Surgery, Istanbul, Turkey, April 19–22, 2004.
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ACKNOWLEDGMENTS
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We would like to thank Dr. SH Javadpour for reviewing this paper.
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REFERENCES
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ABSTRACT
INTRODUCTION
