Perimembranous ventricular septal defect (VSD) with ventricular dilatation

Perimembranous ventricular septal defects (VSDs) are located in the left ventricle outflow tract beneath the aortic valve.

They are the most common VSD subtype in the United States, occurring in 75-80% of cases. Defects may extend into adjacent portions of the ventricular septum