Anomalous mitral 'cleft' with abnormal ventriculo-arterial connection: anatomical findings and surgical implications.

Seven specimens with a 'cleft' mitral valve associated with anomalous chordal fixation and abnormal ventriculo-arterial connection are presented. Four were associated with a discordant ventriculo-arterial connection, two with double-outlet right ventricle, and one with double-outlet left ventricle. In six the chordae from the cleft were attached to the anterior border of a small ventricular septal defect. In the seventh the chordae were attached to an accessory papillary muscle in the left ventricular outflow tract. These clefts differ from those of atrioventricular defects. The cleft is more anterior, there are no septal defects of the atrioventricular canal type, and no deficiency of the basal ventricular septum. Mitral regurgitation or left ventricular outlet obstruction are possible consequences of the anomaly.