When blood flow is disrupted…

There are three main causes for heart valve disease. Heart valves may be defective at birth (congenital heart valve diseases). They may deteriorate over time (degenerative heart valve diseases). The disease may also be acquired through bacterial infection (rheumatic heart valve disease). When the valves are affected, blood flow through the heart valves is disrupted by regurgitation or stenosis.

Regurgitation, also called insufficiency or incompetence, occurs when a valve does not close properly and blood leaks backward instead of moving in the proper one-way flow. If too much blood flows backward, insufficient amounts of blood can travel throughout the body. The heart tries to compensate by working harder; with time the heart ventricle will become enlarged (dilated) and less able to pump blood.

Stenosis happens when the leaflets thicken, stiffen, or fuse together. The leaflets do not open wide enough and only a small amount of blood can flow through the valve. Because of the narrowed valve, the heart must work harder to push blood through the body.