Tricuspid insufficiency associated with aneurysm of the ventricular septum.

Because of the anatomic relation of an aneurysm of the membranous ventricular septum (AMVS) to the tricuspid septal leaflet or because of the tricuspid septal leaflet involvement in the aneurysm formation, dysfunction of the tricuspid valve is likely to occur in patients with AMVS. The auscultatory manifestations of the resultant tricuspid insufficiency (TI) could be masked by the systolic murmur of the ventricular septal defect (VSD), which is often present in these patients. The presence of TI is suggested by phonocardiographic findings in five patients with AMVS and is further supported by intracardiac phonocardiography and angiocardiography. After inhalation of amyl nitrite, a pansystolic murmur appeared in three patients, and the intensity of the pansystolic murmur increased significantly in two patients. Inhalation of amyl nitrite reduces the systemic resistance, resulting in decreased systemic pressure and diminished intensity of the murmur of a small VSD. Augmentation of the systemic venous return is responsible for increased intensity of TI murmur.