A ventricular septal defect (VSD) is a defect in the wall called the septum that is between the heart's two lower chambers called the ventricles. A septal defect is often referred to as a hole in the heart.

Normally, the right side of the heart receives oxygen-poor blood and pumps it to the lungs where it is filled with oxygen. The blood is then sent back to the left side of the heart, which pumps oxygen-rich blood to the rest of the body. But with VSD, the heart pumps inefficiently. The oxygen-rich blood is pumped back to the lungs.

VSD can lead to enlargement of the heart and high blood pressure in the blood vessels of the lungs.

Ventricular Septal Defect
Ventral septal defect
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Most VSDs are a type of congenital heart defect, meaning they are present at birth. It is unclear why VSDs develop, but genetics may play a part. Although rare, some VSDs can occur after a heart attack or trauma.