Taussig-Bing anomaly with straddling mitral valve.

Five patients with the left-sided or intermediate type (Lev) of the Taussig-Bing anomaly were found to have an associated straddling of the mitral valve. In four patients the anomaly of the mitral valve was not recognized preoperatively, and all four died postoperatively. The persistent subpulmonic obstruction caused by the abnormal attachment of the anterior mitral leaflet is considered a significant factor in the poor operative outcome. Retrospective study of angiograms in these four patients revealed diagnostic clues of straddling mitral valve which enabled us to diagnose a fifth patient angiographically and confirm the diagnosis by cross-sectional echocardiography. A surgical approach to correct this association of abnormalities is proposed which avoids operating upon the mitral valve. Its function is thereby preserved, yet the hemodynamic problem caused by the straddling is bypassed. The fifth patient in this series was successfully treated by the proposed operative method.