Mitral valve surgery using right anterolateral thoracotomy: Is the aortic cannulation a safety procedure?

1. PhD in Sciences at FMUSP; Substitute Professor at Faculty of Medicine of the Federal University of Bahia. 2. Associated Professor of the Cardiopneumology Department at FMUSP; Director at Surgical Unit of Heart Valve Diseases at InCor – HC – FMUSP. 3. PhD in Medicine at FMUSP, Assistant Physician – Surgical Division – InCor – HC – FMUSP; Collaborator Professor – FMUSP. 4. PhD in Medicine at FMUSP; Assistant Physician – Echocardiography Division – InCor – HC – FMUSP. 5. Full Professor at FMUSP, Director of the Clinical Unit of Heart Valve Diseases at InCor – HC – FMUSP. 6. Titular Professor of the Discipline of Cardiovascular Surgery at FMUSP; Director of the Surgery Division at InCor – HC – FMUSP. Marco Antonio Vieira GUEDES1, Pablo Maria Alberto POMERANTZEFF2, Carlos Manuel de Almeida BRANDÃO3, Marcelo Luiz Campos VIEIRA4, Max GRINBERG5, Noedir Antonio Groppo STOLF6 Rev Bras Cir Cardiovasc 2010; 25(3): 322-325 ORIGINAL ARTICLE


METHODS
From 1983 through 2008, 100 consecutive patients underwent mitral valve surgery at Heart Institute of University of São Paulo Medical School through a right anterolateral thoracotomy associated with aortic cannulation for cardiopulmonary bypass. This approach to mitral valve was performed in female patients with low risk profile, in order to achieve a better cosmetic result, and in redo cases, to avoid sternotomy and minimize surgical bleeding. Ninety six (96%) of patients were female. The mean of age was 35 ± 13 years (range 13 to 68 years). According to etiology, 80 (80%) were rheumatic, four (4%) congenital, six (6%) degenerative, fi (5%) endocardites and five (5%) miscellaneous. According to NYHA, in the preoperative period, two (2) were in functional class I, 14 (14%) in II, 69 (69%) in III and 15(15%) were in functional class IV. Associated procedures were performed in 12 (12%) patients. Ten (10%) cases were reoperation procedures. Operative and associated procedures performed are shown in Table 1.

INTRODUCTION
Right thoracotomy approach to perform mitral valve surgery was described, in 1954, by Neptune & Bailey [1] and has been widely used until nowadays, with excellent exposure of mitral valve, even in small left atrium. This incision presents favorable cosmetic results, representing a good alternative in young female patients [2].
Despite of it, the midline sternotomy is by far the most common incision for open heart operations, including mitral valve surgery, due to easy access to all cardiac chambers and great vessels [3].
In the 1980's, some authors revisited the mitral valve approach through right thoracotomy in redo cases to avoid sternotomy, minimizing the risk of cardiac damage [4]. Furthermore, was suggested that a limited anterolateral thoracotomy should be preferred to an extended lateral thoracotomy, in order to minimize postoperative pulmonary complications, because it provides a good operative exposure and preserves the integrity of thoracic cage [3][4][5]. Besides, limited thoracotomy is associated to less infection occurrence, less bleeding and earlier postoperative recovery [5].
Femoral cannulation is associated to many complications, such as infection, bleeding, thrombosis and late stenosis, cerebral and coronary embolism [6]. Despite, femoral cannulation is the most common approach to cardiopulmonary bypass in mitral valve surgery through a limited anterolateral thoracotomy [3][4][5]. This approach allows complications occurrence related with femoral cannulation [6].
The aim of this study was to describe the technique and results of mitral valve surgery through a limited right Abstract Introduction: The right anterolateral thoracotomy is an alternative technique for surgical approach of mitral valve. In these cases, femoral-femoral bypass still has been used, rising occurrence of complications related to femoral cannulation. Objective: Describe the technique and results of mitral valve treatment by right anterolateral thoracotomy using aortic cannulation for cardiac pulmonary bypass (CPB).
Methods: From 1983 e 2008, 100 consecutive female patients, with average age 35 ±13 years, 96 (96%) underwent mitral valve surgical treatment in the Heart Institute of São Paulo. A right anterolateral thoracotomy approach associated with aortic cannulation was used for CPB. Eighty (80%) patients had rheumatic disease and 84 (84%) patients presented functional class III or IV.
Conclusion: The right anterolateral thoracotomy associated with aortic cannulation in mitral valve surgery is a simple technique, reproducible and safety.
Descriptors: Mitral valve. Extracorporeal circulation. Thoracic surgery. Heart valves. Surgical procedures, minimally invasive. Data was abstracted from hospital and clinic charts using a special protocol form and were retrospectively analyzed. Follow-up of these patients was obtained by postoperative clinical and echocardiographic evaluations in the outpatients clinic or telephone interview using a structured questionnaire. The Kaplan-Meier method was used to evaluate actuarial survival.

Operative technique
After monitorization and endotracheal anesthesia, the patient was moved to a left semi-lateral position and maintained at an angle of 45 o of operating table to expose the right hemithorax. The patient was draped in usual manner. A 10-12 cm incision was made in the right submammary fold, starting 3-5 cm from the lateral border of the sternum. Breast tissue was mobilized and pleural cavity was entered through 4 th intercostal space. Chest retractor was progressively opened to avoid ribs fracture. Pericardial sac was opened through a horizontal incision as anterior as possible, avoiding phrenic nerve and providing exposure of the ascending aorta.The pericardium was fixed to the wound edge with heavy silk sutures starting near the diaphragm, finishing at aorta reflection. This maneuver is very important to pull down the ascending aorta, achieving a clear exposure of aorta and lateral wall of heart. A moynihan clamp was placed in anterior surface of ascending aorta and a gently traction was made to exposure the site for aortic cannulation.
After a temporary induced hypotension, ascending aorta was cannulated in usual manner and secured by a Rommel tourniquette. Aortic cannula was fixed in a column of towels to avoid kinking position, as shown in Figure 1. After that, bicaval cannulation was performed. As shown in Figure 2, aortic cross clamping was performed using a long curved clamp. Cardioplegia was delivered at aortic root. Mitral valve surgery was performed and decannulation was done in usual manner. Pleural cavity was drainage by one chest tube and chest closed in layers.

RESULTS
Aortic cannulation was performed in all cases and there were no technical difficulties or complications related to the cannulation. There were intraoperative complications in five (5%) cases: right ventricle perforation in one, inominnate vein rupture in one, pulmonary artery lesion in one, ribs fracture in one and pulmonary contusion in one patient. From these complications, three (3%) of them were in reoperation procedures, occurring during heart harvesting. There was no conversion to median sternotomy.
The most important complication in postoperative period was related to pulmonary system, occurring in 11 (11%) patients, but without seriously systemic disorders. Of them, atelectasis occurred in seven (7%) patients, pleural effusion, pneumothorax, pleural fistula, pulmonary thromboembolism, transitory encefalophathy and wound dehiscence occurred in one patient each postoperative complication. Atrial arrythmia occurred in 10 (10%) patients. There was no reoperation due to postoperative bleeding.

Fig. 4 -Freedom from reoperation
There was no in-hospital death. The mean in-hospital length of stay was 8 ± 3 days. Follow-up was 503 patients/ year. In late postoperative period, according to NYHA, 80 (80%) of patients were in functional class I, nine (9%) in II and two (2%) in functional class III. Actuarial survival was 98.0 ± 1.9% ( Figure 3) and freedom from reoperation was 81.4 ± 7.8% in 180 months (Figure 4).

DISCUSSION
The surgical approach to mitral valve through right thoracotomy offers an excellent exposure of the mitral valve, even in patients with small left atrium [2]. Furthermore, associated procedure as closure of atrial septal defect or tricuspid valve surgery can be executed by this approach safely [3].
One of the most important aspects of this technique is the excellent cosmetic result obtained. The scar usually is covered by breast tissue in female patients. Moreover, complications related to sternotomy, as sternal infection or bleeding, is avoided with this technique [3,5]. One of the principal concern about less invasive surgery is the balance between limited exposure and safety of the procedure. In this study, there was no reoperation due to bleeding or inhospital death, what demonstrates the safety of the limited right thoracotomy. This fact probably could be related to the team experience, and also to the low risk profile of the patients included in this study.
Femoral cannulation for bypass was usually performed in mitral valve operations using right thoracotomy. The use of femoral vessels can predispose to complications such as bleeding, dissection, thrombosis, stenosis, lower limb ischemia, lymphatic leakage, local infection and embolic events [6]. The most hazardous complication related to femoral cannulation is retrograde aorta dissection, that can be progressive, with extension to aortic arch or to retroperitonial space. The mortality of this event is high, and its incidence in femoral cannulation ranges between 0.2 and 1.3% [7].
Kirklin and Barratt-Boyes [8] related that one of the disadvantages of this technique is the relative inaccessibility to thoracic aorta. In this report, ascending aorta was cannulated and clamped with safety and without complications in all cases, demonstrating the feasibility of this technique. Less invasive methods have been successfully developed and represent valuable alternatives for mitral valve surgery. Reduction in surgical trauma is the angle key to improve patient comfort and reduce hospital stay. Furthermore, development of novel technologies as robotics and video-assisted thoracoscopy surgery enables implementation of this approach on clinical practice [9]. Limited right anterior thoracotomy associated with aortic cannulation in mitral valve surgery is a simple technique, reproducible and safe. Furthermore, complications related to femoral cannulation were avoided with this technique.