Ann Thorac Surg 2000;70:1958-1961
© 2000 The Society of Thoracic Surgeons
Original article: cardiovascular
Aortic root replacement by ministernotomy: technique and potential benefit
Lizhong Sun, MDa,
Jun Zheng, MDa,
Qian Chang, MDa,
Yue Tang, MDa,
Jun Feng, MDa,
Xiaogang Sun, MDa,
Xiaodong Zhu, MDa
a Department of Cardiac Surgery, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, People's Republic of China
Accepted for publication May 7, 2000.
Address reprint requests to Dr Sun, Department of Cardiac Surgery, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100037, People’s Republic of China
e-mail: slzh{at}public3.bta.net.cn
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Abstract
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Background. Although minimally invasive surgical procedures have aroused much interest in cardiac surgery, difficulty still exists with its application in most of the operations on great arteries. This report summarizes our initial experience of aortic root replacement by a superior ministernotomy in terms of operative indications, operative techniques, and potential benefits.
Methods. Between July 1999 and September 1999, 8 patients who were diagnosed with Marfan syndrome with aortic valve regurgitation underwent aortic root replacements with composite grafts. Clinical characteristics, in-hospital outcomes, and postoperative stay of these patients were compared with data of patients who had undergone Bentall procedure by standard median sternotomy from January to September 1999.
Results. There was no death in either group of patients. Demographics were similar between the two groups of patients. In the mini-incision group, the mediastinal drainage was significantly less than the standard incision group. The mean operating time was significantly longer than that in the standard incision group. The cardiopulmonary bypass time and aortic cross-clamping time were similar in both groups of patients. The mean intubation time, postoperative blood transfusion amount, duration of intensive care unit stay and postoperative hospital stay were less than that of the standard incision group; however, they all showed no statistical significant difference.
Conclusions. Aortic root replacement by a superior ministernotomy in cardiopulmonary bypass with cannulas through the femoral artery and femoral vein or right atrium is a safe, reliable procedure with excellent exposure. The procedure provides a potential benefit of less trauma, quick recovery, and reduction of mediastinal drainage and reduction of blood transfusion.
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Introduction
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Although minimally invasive procedures have aroused much interesting in cardiac surgery in recent years and many studies suggested that patients would benefit from smaller incisions than standard incisions [1–4], a considerable difficulty still exists with the application of minimally invasive techniques in most aortic surgeries. Aortic root replacement is the most effective therapy for proximal aortic aneurysm with aortic regurgitation. Since its introduction in 1968 [5], this procedure has been performed widespread. Our initial experience of aortic root replacements by a superior ministernotomy is presented in this article.
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Material and methods
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Between July and September 1999, 8 patients underwent aortic root replacement by a superior ministernotomy. To establish the comparable groups, we included a total of 21 patients who had undergone Bentall operation by the standard median sternotomy (STD) between January and September 1999. However, we must emphasize the fact that the study is a nonrandomized, retrospective review of our initial experiment.
Patients having a superior ministernotomy were defined as the MINI group. Six men and 2 women were studied, with a mean age of 41.6 ± 8.2 years (range, 35 to 59). All patients had the stigmata of Marfan syndrome, combined with aortic valve regurgitation. Diagnosis was made by echocardiography, magnetic resonance imaging, and computed tomography. None of the patients in this group were excluded from statistical analysis. Patients having a standard median sternotomy were defined as the STD group. Elective conventional Bentall procedures by standard median sternotomy were performed in 36 patients before September 1999. Fifteen patients were excluded from statistical analysis because of combining operations including total aortic arch replacement and concomitant mitral valve replacement. There were 19 men and 2 women, with a mean age of 40.8 ± 10.1 years (range, 26 to 63). Patient characteristics of the two groups are summarized in Table 1. All patients had at least 3 months follow-up after hospital discharge.
Technique of mini-incision repair
When general anesthesia was finished, a midline incision was performed, about 10 cm to 13 cm long, starting from the suprasternal notch to the level of nipples. The sternum was divided from the top down in midline and ended at the fourth intercostal space, spread mildly by a small retractor. We divided the sternotomy to the right fourth intercostal space in the first three operations, but found that it could provide better exposure of the pulmonary trunk if the sternum was divided to the left intercostal space. Opening of the upper pericardium provided good exposure of the ascending aorta, aortic root and arch, superior vena cava, right atrial appendage, and pulmonary trunk. The left femoral artery was cannulated for perfusion. A dual-stage venous cannula was placed through the left femoral artery in 6 patients, and the right atrial appendage or the superior vena cava in 2 patients, respectively. The cannula of the left ventricular vent was placed in the pulmonary trunk. Isolated replacement of the aortic root was performed under moderate hypothermic cardiopulmonary bypass. Circulatory arrest was not used. After resection of the aneurysmal wall, ostia of the right and left coronary arteries were shaped buttonlike. Different methods were used according to different degrees of pathologic changes of aortic valves. Normal or nearly normal aortic valves should be retained if possible; annulorrhaphy of the aortic ring was first used if necessary. There were two satisfying aortic root replacements with reservation of the aortic valve in this group. If the aortic valves were irreparable, aortic valvular resection and concurrent root replacement with grafts of a composite valve were needed. When the proximal end was anastomosed to the aortic annulus, fenestration of approximately 1.0 cm to 1.5 cm was made in the graft wall opposite the ostium of each coronary artery, and the ostium was anastomosed to the graft with continuous 4-0 polypropylene sutures. The ostia should not be dissociated from the aneurysm wall and should be directly sutured to the graft if the aneurysm wall tissue appears friable or dissected. The distal ascending aorta was anastomosed to the distal composite graft. Before finishing the intracardiac manipulations, a dose of warm blood (37°C) during cardioplegia was administered routinely, which could prompt the recovery of spontaneous sinus rhythm. Finally, the mediastinum was drained with two chest tubes through the left and right fourth intercostal space.
Postoperative management was similar for all patients according to the intensive care unit protocols for open heart operations. All chest tubes were removed on the first or second postoperative day. Operative data and postoperative data are listed in Tables 2 and 3.
The patient data was compared between the two groups using the Student’s t test and 
2 test where appropriate. Descriptive statistics are given as mean ± standard deviation. A p value less than 0.05 was considered significant.
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Results
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In the MINI group, there were 3 patients whose heart recovered systole automatically and the other 5 patients recovered their normal heartbeat after electrical defibrillation. All patients were weaned from cardiopulmonary bypass uneventfully. Postoperative echocardiography and computed tomography demonstrated that the aortic grafts were unobstructed with no contrast-medium leakage, the artificial valve prosthesis functioned well, and the sizes of the left ventricle were reduced significantly (56.1 ± 9.1 vs 68.8 ± 8.0 mm). All patients were satisfactorily rehabilitated and discharged.
Demographics were similar among the two groups (Table 1). In the MINI group, the mean operative time was significantly longer than that in the STD group (255.0 ± 27.2 vs 213.3 ± 47.2 minutes, p < 0.05) (Table 2). The mean postoperative mediastinal drainage in the MINI group was significantly less than in the STD group (456.2 ± 247.4 vs 1007.6 ± 566.0 mL, p < 0.05) (Table 3). The mean and cardiopulmonary bypass time (78.1 ± 6.9 vs 88.6 ± 24.7 minutes), cross-clamp time (58.2 ± 5.2 vs 63.3 ± 12.2 minutes), intubation time (14.8 vs 18.4 hours), postoperative blood transfusion (400 vs 690 mL, range from 0 to 1600 mL), and hospital stay (12.1 vs 16.1 days) in the postoperative period in the MINI group were less than those in the STD group (Tables 2 and 3). Two patients in the MINI group needed no blood transfusion but those differences indicated no statistical significance. The average length of intensive care unit stay was similar in both groups (3 vs 2.9 days).
There was no postoperative death in either group of patients. The total incidence of complication in either group was listed in Table 3. All patients were followed up for at least 3 months, and were in New York Heart Association functional class I and II. Echocardiography showed all prostheses functioned well and the aortic grafts were unobstructed. The postoperative mean left ventricular end-diastolic diameters were significantly reduced (Tables 1 and 3).
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Comment
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Excellent results have been documented with the conventional aortic root replacement. This report is to discuss the operative indication, basic perfusion, operative techniques, and potential benefits using minimally invasive techniques.
This approach is especially indicated in aortic valve regurgitation of isolated aortic root aneurysm, and in ascending aortic or partial aortic arch replacement [6]. Superior ministernotomy offers an ideal view of the root, ascending and arch of aorta, main pulmonary artery, superior vena cava, and the right atrial appendage. There were no difficulties in the cardiopulmonary resuscitation as witnessed by five successes on the first time of defibrillation in this group. For those patients with very large hearts, intraoperative defibrillation may become difficult and devices for external defibrillation should be prepared. Administration of warm-blood cardioplegic solution before intracardiac manipulations is beneficial to the recovery of cardiac systole.
There were 6 patients cannulated through the left femoral artery and left femoral vein to set up moderate hypothermic extracorporeal circulation. Venous cannulation was performed using a femoral dual-stage cannula with the aid of suction of the main pulmonary artery with sufficient venous drainage. If difficulties existed with femoral vein cannulation or there was no femoral dual-staged vein cannula, an atrial dual-staged cannula could be inserted through the right atrial appendage or superior vena cava. There were two such patients in this series with excellent venous drainage, but the tubes might be disadvantageous to the manipulations more or less. Cannulation through the left femoral artery and left femoral vein provided calm operation field and good exposure. Through the incision of partial upper sternotomy, cannulation for the left ventricle vein through the right superior pulmonary vein would be inconvenient. Suction through a cannula placed in the pulmonary trunk would be a good alternative that provides a field of vision without blood.
As many authors have suggested [2, 7], minimally invasive procedures take more time to perform. The extra operative time was mostly spent on homeostasis. Our data demonstrated that mini-incision surgery reduced the amount of blood lost and postoperative mediastinal drainage than that of full median sternotomy. On the other hand, we must emphasize that special attention has been given to hemostasis in surgery by ministernotomy. Special care also should be taken for these patients when placing chest tubes and postoperative monitoring, because there is a potential danger of pericardial effusion after partial sternotomy operations.
Patients in the MINI group did not seem to complain of postoperative pain after regaining consciousness any more than the patients of the STD group, and did not require any additional narcotics. The MINI group patients appeared to return to normal activity sooner. Because most patients had a certain degree of interest in cosmesis, patients in the MINI group show more satisfaction with the operation results.
It is apparent that the extension of minimal incision is a little harder than full median sternotomy. Our experience demonstrated that the mini-incision provided enough field of vision for the procedure and did not need excessive traction of the sternum. In the MINI group, the clavicular-sternal-rib cage continuity is preserved as a result of half-division of the sternum, and it is beneficial to the pulmonary function of the patients. Another potential benefit is reoperation for patients who need an additional cardiac operation [8] or coronary bypass grafts in the future. The use of partial sternotomy might make reoperative operations easier than full sternotomy operations, because less mediastinal tissue disturbance and adhesion were generated. From this point of view, mini-incision causes less tissue damage and trauma than corresponding full incision procedures.
This was our initial experience with minimal invasion of aortic root replacement, and the number of patients was too small to draw firmer conclusions.
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References
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Abstract
Introduction
