Introduction

Currently, mitral valve operations have become common and routine procedures, and technical refinement has continuously developed. New attempts were made to apply less invasive techniques to reduce surgical trauma. The results were suggested that there was less bleeding and pain, and a low risk of infection, and better cosmetic results _{1 2}.

We performed mitral valve replacement using an incision through the fourth right intercostal space and the mean length was 7.2±1.2 centimeter. In this paper we reporte the results of our experience with this approach.

Material and Methods

After approval by the local ethical committee, 24 consecutive patients (18 woman, 6 man, mean age 29±3.8 years) with pure rheumatic mitral valve disease were included in the study. All patients gave written informed consent after the study protocol and the potential risks associated with the procedure had been outlined in detail. Demographics and preoperative patient data are summarized in Table 1.

Figure 1

Table 1:Demographic data

After anesthetic induction, airway was intubated with a left-sided double-lumen endobronchial tube (Mallinckrodt, Athlone, Ireland). An arterial pressure line was placed in the right radial artery. A pulmonary artery catheter was inserted through the right jugular vein. Patients were positioned for a right anterolateral thoracotomy, with the right side elevated 30 degrees, the right arm was wrapped with adequate padding to avoid peripheral nerve injury and suspended over the head. The right groin was prepared and draped for emergency state to allow access to the femoral vessels. A small anterior thoracotomy incision was made under the infra-mammary groove. The incision started approximately 3 cm lateral to the right sternal edge and extended about 10 cm posteriorly. The chest was opened through the fourth intercostal space. Right internal mammary vessels always respected. The pericardiotomy was performed longitudinally, anterior to the phrenic nerve, and was suspended posteriorly.
After heparin administration, the arterial cannula has been placed directly into the ascending aorta by suspending of the aorta with a dacron tape. Two caval cannulas were inserted into the right atrial appendage, and the right atrial wall.

Cardiopulmonary bypass under mild hypothermia (32°C) was started and caval tapes were snared. Aortic cross-clamping was performed and cold blood cardioplegia was administered into the proximal ascending aorta. A cannula was placed in the right upper pulmonary vein for venting and de-airing. After cardiac arrest has been established, the left atrium was opened and mitral valve repair (9 patients) or replacement (15 patients) was performed under direct vision. After completion of the procedure the left atrium was closed by continuous suturing. De-airing was provided by the antegrade cardioplegia line and pulmonary vein catheter. If necessary, defibrillation was performed with internal paddles. Before all cannulas were withdrawn transesophageal echocardiographic (TEE) controls were obtained. After weaning from cardiopulmonary bypass, ventricular pacing wires, pericardial and right pleural drains were placed. The pericardium was closed partially and the thoracotomy was closed in standard fashion after intercostal nerve block was accomplished by bupivacain for postoperative analgesia.

Statistics

Data are presented as the actual number of occurences in a group and as the mean plus or minus the standard error. Nonpaired Student’s t tests were used to compare measured data between the groups. They were considered significant at a p value of less than 0.05.

Results

In all patients, the mitral valve was accessible through the right anterior minithoracotomy. Perioperative courses was summarized in Table 2.

Figure 2

Table 2: Periopertive course of both groups. (NS: statistically insignificant)

The mean length of incision was 7.2±1.2 cm. In 9 patients, mitral commissurotomy was performed successfully and was demonstrated by TEE. Fifteen patients underwent mitral valve replacement with preservation of the posterior leaflet. St. Jude Medical mitral valve was preferably used. In 19 patients, a spontaneous rhythm presented after aortic declamping, whereas 5 patients required one or more internal defibrillations of 5 to 20 joules.Mean intubation times were 7.2±4 hours. Intensive care unit and hospital stays were 16±6 hours and 5.9±2 days, respectively.

There weren’t any patients for reexploration for bleeding. None of the patients died in the perioperative period or at follow-up. At discharge after mitral valve repair, all patients had normal or only trivial mitral regurgitation. All implanted valves were functioning normally, as shown by postoperative echocardiographic studies. All patients had at least returned to their preoperative activity level, and according to New York Heart Association classification they were in class 1.

We compared the procedures done through a right anterior minithoracotomy incision with those done through a median sternotomy in order to evaluate cost effectiveness (Table 2). The study group was compared with 24 patients undergoing the same procedure through median sternotomy. The costs of all prostheses were removed from the analyses and only direct costs were analyzed. Direct costs were reduced by 15% (p<0.05) in patients undergoing minithoracotomy. Hospital stay was shorter then within the median sternotomy group (5.9±2 days vs 8.8±3 days; p<0.05). The postoperative chest tube drainage was lower then in the median sternotomy group (230±140 ml vs 420±190 ml; p<0.05).

Discussion

Interest in the minimally invasive surgical techniques in cardiac surgery have been increased tremendously. Minimally invasive procedures were introduced in expectation of reducing recovery time, postoperative pain, cost, and favorable cosmetic results as compared with conventional surgery.

The right thoracotomy approach was recently updated as an alternative to repeat sternotomy for redo mitral valve operations _{3 4 5 6} and more recently lesser invasive approaches for mitral valve surgery or many other cardiac operations had been of great concern _{1 2 7 8}.

Because of the smaller incision, bleeding of the right anterior thoracotomy incision was less than the sternotomy. It was also thought that a sternotomy would be bleeding, even after it has been reapproximated ₁.

Some authors have performed femoral or external iliac cannulation, but we have thought that it caused several problems on the groin and the aorta. Direct aortic cannulation has been generally advocated especially in older patients because they seem avoid groin complications such as wound infection, hematoma, lymph fistula and femoral artery stenosis _{8 9 10 11}. During peripheral arterial cannulation or endovascular aortic clamp insertion there might be aortic dissection ₈.

Another potential advantage of minimally invasive approach is that the pericardium is not opened over the right ventricular outflow tract. This is the site that is most commonly injured during reoperation. Reoperation is considerably easier and safer if the pericardium in this area has not been interrupted ₁.

There was less trauma and less pain reported by the patients. With median sternotomy, the most common pain reported by patients was back pain, mostly due to the traction on the ribs and thoracic ligaments. The smaller incision and intercostal nerve blocking in the right anterior minithoracotomy reduced this discomfort. Additionally, the smaller incision reduced the risk for wound infection and blood loss. Patients recovered more rapidly and were discharged from hospital earlier, reducing total hospital cost. The operative procedure reduces surgical trauma and is cosmetically more attractive for patients. In our series, all patients did benefit from this approach which has better cosmetic results than the others. Mean duration of cardiopulmonary bypass and cross clamp times were similar to our standard sternotomy series but the period was very long between the beginning of operation to the establishment of cardiopulmonary bypass in the early phase of the study. However there was a gradual improvement in the our surgical performance.

We believe that a 4-5 cm incision along the thorax together with a 4-5 cm incision in the groin were not lesser invasive than a 7 cm incision in the chest wall only. The results were very well correlated with the median sternotomy approach.