Heart valve disease occurs when a heart valve is damaged or narrowed and does not control or allow the normal flow of blood through and out of the heart. Causes of heart valve disease include congenital heart disease, an abnormal valve, or a rupture of a valve.

Heart valves operate like one-way gates, helping blood flow in one direction between heart chambers as well as into and out of the heart. A normal heart valve has flaps, called leaflets. When the heart pumps, the leaflets open one way to allow blood to flow through. Between heartbeats, the leaflets should close to form a tight seal so that blood does not leak backwards through the valve.

If the heart valve is damaged, the leaflets may not form a tight seal, and blood may leak backwards through the valve. This leakage is called regurgitation.

Heart valves can also become narrowed, which may block the flow of blood through the heart. This narrowing is called stenosis.