We report the case of a patient with mesocardia, mitral restenosis, and mitral regurgitation. He had undergone an open mitral valvotomy 4 years earlier and, therefore, presented us with a problematic approach to the mitral valve. In such cases, access to the mitral valve is almost impossible due to the position of the valve, which is more posterior and to the left of a normal valve, and due to adhesions from the previous surgery. We approached the mitral valve through the left atrial appendage and replaced the mitral valve with a mechanical prosthesis.

We report the case of a patient with mesocardia and severe mitral restenosis who had undergone open mitral valvotomy 4 years earlier. He required reoperation and mitral valve replacement. Many approaches to mitral valve replacement have been described, including various methods of entering the chest and the left atrium to gain access to the valve. When the operation involves repeat open-heart surgery in a patient with mesocardia, the surgical approach has to be planned carefully.

In March 2003, a 36-year-old man presented at our institution with a history of atypical chest pain and dyspnea; he was in New York Heart Association functional class II. He had undergone open mitral valvotomy through a median sternotomy for mitral valve disease 4 years earlier, at another hospital. Medical records describing the previous surgery were not available. The patient had experienced atrial fibrillation since the 1st surgery and was being given digoxin, diuretic therapy, and warfarin. When he reported to our outpatient clinic, he was in atrial fibrillation with a heart rate of 90 beats/min, systemic blood pressure of 130/80 mmHg, and jugular venous pressure of 4 cm H₂O. On cardiac auscultation, the 1st heart sound was loud. At the xiphoid process, there was a systolic murmur with a mid-diastolic rumble that was barely audible at the axilla. The 2nd sound was loud in the pulmonary area.

Electrocardiography showed atrial fibrillation with a controlled ventricular rate. Two-dimensional echocardiography revealed severe mitral valve stenosis with moderate regurgitation, moderate tricuspid valve regurgitation, and mild aortic valve regurgitation. The right ventricular systolic pressure was 65 mmHg, and the left atrial systolic pressure was 53 mmHg. The mitral valve was thickened, and the posterior mitral leaflet was fixed and doming, with commissural fusion. Moderate subvalvular fusion and a speck of calcium on the posterior mitral leaflet were noted. The mitral valve area was 1.0 cm², and there was moderate mitral regurgitation with a jet area of 5.4 cm². Chest radiography revealed mesocardia (Fig. 1).

Fig. 1 Chest radiograph shows mesocardia.

The patient was taken to surgery for reoperation to replace the mitral valve. We entered the chest through a median sternotomy. Just behind the inner table of the sternum, the anterior wall of the heart was attached with dense adhesions. The wall was separated from the sternum by releasing the adhesions, and a small retractor was placed for better viewing. The left anterior descending coronary artery was visible at the midline just behind the median sternotomy (Fig. 2). The adhesions were too dense to get a proper plane of dissection on either side; however, those on the left were not quite so bad. We were able to release the inferior surface of the heart from the diaphragm. On the left side, the left atrial appendage, pulmonary artery, and left lateral ventricular wall were then dissected free from the pericardium. A small area of the aorta could be dissected for cannulation, but the right atrium was completely adherent to the mediastinal pleura. Therefore, we attempted to open the right pleura in order to cannulate the right atrium through the right mediastinal pleura. Unfortunately, the right lung was densely adherent to the chest wall, the right atrium, and the mediastinal pleura. The superior vena cava (SVC) was dissected with great difficulty and was cannulated for cardiopulmonary bypass with aorta–SVC cannulation. Next, right atrial dissection was attempted; however, there were several Ethibond sutures on the right atrium, to which the lung was adhering. Near the aortic root, the right atrial appendage area was freed just enough to admit the inferior vena cava cannula. The pulmonary artery and left atrial appendage were dissected free from one another.

Fig. 2 Arrow in the intraoperative photograph shows the left anterior descending coronary artery just below the median sternotomy.

We decided to replace the mitral valve through the left atrial appendage, with an incision that extended posteriorly to the body of the left atrium. No intervention was required for the moderate tricuspid regurgitation, because it was secondary to the mitral valve disease and the central venous pressure was 10 cm H₂O. Cold blood cardioplegia was achieved through the aortic root, and the patient was cooled to 28°C. There was no left ventricular distention.

As the approach was made through the left atrial appendage, the mitral valve was visible without retraction. A few stitches were placed to retract the incised edges of the left atrial appendage (Fig. 3), and the mitral valve was excised. The valve was thick and puckered, with gross subvalvular fusion. A 25-TTK Chitra Heart Valve mechanical prosthesis (TTK Healthcare Ltd; Chennai, India) was placed in the mitral position with 2–0 Ticron pledgeted sutures (Fig. 3). The left atrial appendage was de-aired and closed. The aortic root was vented and the cross-clamp released. The patient was rewarmed and weaned from cardiopulmonary bypass with only 2.5 μcg/kg/min of dobutamine support. He was in atrial fibrillation, with a controlled ventricular rate and stable hemodynamics. The patient's postoperative recovery was uneventful. Five months after surgery, the patient was asymptomatic and the mitral prosthesis was functioning well.

Fig. 3 Intraoperative photograph shows the ease both of visualization and of replacement of the mitral valve through the left atrial appendage without retraction.

Median sternotomy is the conventional approach for mitral valve surgery. For reoperations, the right anterior thoracotomy and right posterolateral thoracotomy are also becoming popular to avoid anterior adhesions. In addition, entry to the mitral valve requires special planning. Published methods include the superior approach,^1,2 biatrial approach,³ and transatrial superior approach.⁴ Arrhythmias and heart block complications have been reported with use of the transatrial superior approach,² although it provides very good visibility of the mitral valve. In the superior approach, the closure of the incision has to be perfect² before discontinuation of cardiopulmonary bypass, because the approach to the area becomes difficult later. Mitral valve visualization is definitely better through a right thoracotomy in the case of reoperation in a patient with mesocardia, provided that the previous surgery was performed via a conventional left atrial approach. De-airing after bypass is a problem with this approach due to the remoteness of the left ventricular apex and left atrial appendage. Because our patient had mesocardia and we had no previous surgical report, we were not sure whether the previous mitral valve approach had been trans-right atrial and transseptal. Had that been the case, approaching the right atrium through a right thoracotomy would have presented great difficulty because of adhesions. Considering this, we performed a repeat sternotomy. Difficulty in accessing the right atrial side led us to believe that the previous approach had been transseptal through the right atrium. Given this situation, we determined that it was simpler to dissect the left side of the heart; moreover, the mesocardia facilitated an approach through the left atrial appendage. A superior or biatrial approach⁴ could have been performed but would have required more extensive surgical dissection and suturing.

Although it is not in common use, an approach to the mitral valve through the body of the left atrium has been mentioned in the literature⁵ and the advantages discussed. The advantages were evident in the surgical treatment of this patient. We believe that prior planning and a careful approach to the mitral valve led this patient with mesocardia to an uneventful recovery.

We thank Mrs. G.K. Meera and Mrs. Revathy Vijaykumar for their help in editing the manuscript. Our special thanks to Mr. Pary Uma for his photography.