Normal variations in tricuspid valve attachments to the membranous ventricular septum: a clue to the etiology of left ventricle-to-right atrial communication.

In 39 out of 95 normal specimens, there was either no commissure between the anterior and medial leaflets of the tricuspid valve, which resulted in an interrupted valve margin at the center of the membranous ventricular septum, or an incompletely formed commissure. It is suggested that one end of this spectrum of normal anatomic variations could have a direct relationship to VSD associated with left ventricle-to-right atrial communication.