Congenital mitral-aortic discontinuity.

Mitral-aortic (M-A) discontinuity is an uncommonly observed congenital malformation. From the embryologic point of view, it is a failure of the superior endocardial cushion of the A-V canal reach and insert into the aortic root (the mitral-aortic fibrous trigone). It should be differentiated from aorto-left ventricular discontinuity, a complication of endocarditis with excavating abscesses without boundaries. In congenital mitral-aortic discontinuity, the anterior leaflet of the mitral valve fails to insert into the aortic root. We report our experience with 2 patients. In patient 1, the severe left ventricular outflow obstruction was mainly caused by the mobile anterior leaflet of the mitral valve.