Accessory tissue of the tricuspid valve protruding into the left ventricle through a septal defect

We report the pathologic findings in 13 cases with accessory tissue originating from the tricuspid valve and protruding into the left ventricular outflow tract through a ventricular septal defect (VSD). In eight cases the accessory tissue formed a pouch, the walls of which were similar to the tissue of the normal tricuspid valve. In five cases, papillarylike masses of young connective tissue formed the accessory tissue. The degree of left ventricular outflow tract obstruction was mild in five cases, intermediate in five, and severe in three. Adhesions to the rims of the VSD causing obstruction of the VSD were seen in ten cases. Associated anomalies were present in all cases. The most frequent associated anomalies other than the tricuspid valvular anomalies and the VSDs were transposition of the great arteries and a variety of vascular anomalies.