Ventricular septal defect (VSD), a heart problem that develops before birth (congenital), is an opening in the wall that separates the lower chambers of the heart. Most ventricular septal defects are small and do not cause a problem.

A large, untreated ventricular septal defect may result in the lower left heart chamber's inability to pump enough blood to the body and too much blood going to the lungs.

Treatment is not needed in cases where a ventricular septal defect is small or closes on its own. Surgery or a catheter procedure may be done to close the hole.