Cleft anterior leaflet of the mitral valve with intact septa. A study of 20 cases.

Twenty pathologic specimens of heart, each with a cleft in the anterior leaflet of the mitral valve not associated with septal defects of persistent common atrioventricular canal (isolated cleft of the mitral valve), were studied. In 9 cases, there were either no associated anomalies or ones not of functional significance. In each of the other 11 cases there were other significant associated cardiac anomalies, including ventricular septal defect and d-transposition of the great arteries. Functional consequences of the mitral anomaly were mitral insufficiency, subaortic stenosis, or both. Mitral insufficiency was related principally to the width of the cleft. Subaortic stenosis, when present, was due to the position of insertion of accessory chordae in the ventricular septum in a position under the commissure, between the left and right aortic cusps or under the right aortic cusp.