The septum is the wall that separates the lower chambers of the heart, the ventricles. Most Ventricular Septal Defects (VSD) are congenital. Usually, there is an opening in the wall between the ventricles that closes before birth, so that at birth oxygen-rich blood is prevented from mixing with the oxygen-poor blood. When the hole does not close, it may cause higher pressure in the heart or reduced oxygen to the body.
Usually, closure is recommended for small VSDs, especially if there's been an episode of endocarditis which is a heart infection that may be due to the VSD, or if the location of the VSD affects the function of one of the heart valves. If the VSD is large, the pressure in the lungs determines whether it can be closed in an adult patient.
VSD closure is usually performed by sewing a patch of fabric or pericardium (the normal lining around the outside of the heart) over the VSD to close it completely. The normal heart lining tissue eventually grows to cover this patch and it becomes a permanent part of the heart. Some defects can be sewn closed without a patch. It's now possible to close some types of VSDs in the catheterization laboratory using a special device that can "plug" the hole.
Procedures to repair the defect, sometimes referred to as a ventricular aneurysm repair, may be performed as an open procedure or, in some cases, as a minimally invasive procedure may be suggested using robotic assisted surgical procedures or procedures done in the cardiac catheterization lab.