Surgical management of the straddling mitral valve in the biventricular heart

The straddling mitral valve in the biventricular heart is a rare condition that may complicate biventricular repair.

Treatment and outcomes in 5 consecutive patients who underwent primary repair between 1992 and 1997 were reviewed. Their ages at repair ranged from 2 months to 8 years. Three patients had a double-outlet right ventricle with a subaortic (n = 2) or subpulmonary (n = 1) ventricular septal defect. Two patients had transposition of the great arteries (S,D,D), a ventricular septal defect, and left ventricular outflow tract obstruction. The attachments of the papillary muscles of the straddling mitral valves were located on the right ventricular aspect of the ventricular septum. Four patients underwent baffle partitioning of the ventricular cavity. The baffle suture line was used to secure the chordae tendineae crossing the ventricular septal defect, or was intentionally omitted at the papillary muscle. The right ventricular outflow tract was reconstructed with patch augmentation, an extracardiac conduit, or an arterial switch operation. One patient with transposition who had a giant papillary muscle to the straddling mitral valve associated with abnormal insertion of the tricuspid valve on the conal septum underwent univentricular repair.

There were no early or late postoperative deaths. There was no mitral valve dysfunction, left ventricular outflow tract obstruction, or heart block in the 4 patients who underwent biventricular repair.

Although there are several exceptional situations in which ventricular partitioning may result in early and late complications, a straddling mitral valve does not preclude biventricular repair.