Heart valves can become diseased as the result of the natural aging process, causing the valve to wear out. This can be accompanied by the accumulation of calcium deposits, causing the valves to narrow (stenosis) or leak (regurgitation). Rheumatic fever and endocarditis (inflammation of the lining of the heart) can also damage heart valves.

 
Defective valves can be surgically replaced by mechanical valves or biologic (tissue) valves. Mechanical valves, constructed of a metal or plastic, are extremely durable and may last a lifetime. Patients who receive a mechanical valve, however, must remain on anticoagulant medications for the rest of their lives. Long-term use of anticoagulants increases the risk of bleeding problems.

Biologic valves come from pig (porcine) or cow (bovine) tissue, or from a human cadaver (homograph). Biologic valve replacement does not require the patient to take anticoagulant medications. These valves are not as durable as mechanical valves and will eventually need to be replaced. New biologic valves, bioengineered to last far longer than current biologic valves, are the latest advancements in valve replacement technology.