An incidental aneurysm of the interventricular membranous septum.

Aneurysm of the interventricular membranous septum is a very rare cardiac anomaly in the absence of ventricular septal defect. We report the case of a 22-year-old man with aneurysm of the interventricular membranous septum incidentally determined during aortic valve surgery. The patient underwent successful aortic valve replacement and aneurysm repair. Patients with the aneurysm of the interventricular membranous septum who are asymptomatic must be followed closely in terms of potential cardiac complications.