Ventricular Septal Defect - Location and Etiology

This drawing illustrates the location of several types of congenital ventricular septal defects. The two most common sites are in the membranous septum and in the muscular septum.

Those in the membranous septum are located just under the aortic valve, when viewed from the left ventricle, and behind the tricuspid valve, beneath the crista supraventricularis when viewed from the right ventricle.

Muscular defects are often in the mid portion of the septum, as indicated in the drawing. They can be anywhere in the septum and can also be multiple.

Supracristal defects are just below the pulmonary valve and above the crista supraventricularis, when viewed from the right ventricle.

A ventricular septal defect may be acquired. Possible causes include a myocardial infarction that destroys part of the muscular septum and penetrating trauma to the heart.