Abnormal mitral valve anatomy in d-transposition of the great arteries: anatomic characterization and surgical outcomes.

Mitral valve anomalies can occur with S,D,D-transposition of the great arteries (d-TGA). Their influence on surgical technique and outcome after an arterial switch operation (ASO) has not been well described. Patients with d-TGA who underwent ASO from February 1990 to January 2011 were identified. Echocardiograms, operative reports, hospital course, and latest follow-up evaluation were reviewed. A total of 218 infants underwent ASO at a median age of 15.8 days. Survival was 95 % during a mean follow-up period of 60 months. Nine patients (4 %) were found to have similar mitral valve anomalies including anterior malalignment conoventricular septal defect, anterior displacement of the mitral valve toward the left ventricular outflow tract (LVOT), malpositioning of the posteromedial papillary muscle, unusual rotation of the mitral valve leaflets orienting the commissure toward the anterior ventricular septum, and redundant mitral valve tissue extending into the LVOT. Coarctation was more frequent in this subgroup (33 vs. 10 %; p = 0.05). Preoperative echocardiography consistently indicated suspicion of a cleft mitral valve with chordal attachments to the ventricular septum causing potential LVOT obstruction. Operative inspection did not identify a cleft or anomalous attachments in any patient, and no valvuloplasty or chordal manipulation was performed. The average hospital length of stay were similar (30.7 vs. 25.3 days; p = 0.54). One patient died late due to progressive LVOT obstruction, and one required heart transplantation. No patient had significant mitral valve regurgitation. We conclude that mitral valve anomalies associated with d-TGA are rare but present with consistent anatomic features and higher risk of coarctation. Unusual mitral valve apparatus positioning and chordal redundancy can suggest the need for valvuloplasty and chordal resection preoperatively, but this is rarely needed.