Your heart valves lie at the exit of each of your four heart chambers and maintain one-way blood flow through your heart. The four heart valves make sure that blood always flows freely in a forward direction and that there is no backward leakage.

Blood flows from your right and left atria into your ventricles through the open mitral and tricuspid valves.

When the ventricles are full, the mitral and tricuspid valves shut. This prevents blood from flowing backward into the atria while the ventricles contract (squeeze).

As the ventricles begin to contract, the pulmonic and aortic valves are forced open and blood is pumped out of the ventricles through the open valves into the pulmonary artery toward the lungs, the aorta, and the body.

When the ventricles finish contracting and begin to relax, the aortic and pulmonic valves snap shut. These valves prevent blood from flowing back into the ventricles.

This pattern is repeated over and over, causing blood to flow continuously to the heart, lungs, and body.

What Are the Types of Heart Valve Disease?

There are several types of heart valve disease:

Valvular stenosis. This occurs when a heart valve opening is smaller than normal due to stiff or fused leaflets. The narrowed opening may make the heart work very hard to pump blood through it. This can lead to heart failure and other symptoms (see below). All four valves can be stenotic (hardened, restricting blood flow); the conditions are called tricuspid stenosis, pulmonic stenosis, mitral stenosis, or aortic stenosis.
Valvular insufficiency. Also called regurgitation, incompetence, or "leaky valve", this occurs when a valve does not close tightly. If the valves do not seal, some blood will leak backwards across the valve. As the leak worsens, the heart has to work harder to make up for the leaky valve, and less blood may flow to the rest of the body. Depending on which valve is affected, the condition is called tricuspid regurgitation, pulmonary regurgitation, mitral regurgitation, or aortic regurgitation.

What Causes Heart Valve Disease?

Heart valve disease can develop before birth (congenital) or can be acquired sometime during one's lifetime. Sometimes the cause of valve disease is unknown.

Congenital valve disease. Most often affects the aortic or pulmonic valve. Valves may be the wrong size, have malformed leaflets, or have leaflets that are not attached correctly.

Bicuspid aortic valve disease is a congenital valve disease that affects the aortic valve. Instead of the normal three leaflets or cusps, the bicuspid aortic valve has only two. Without the third leaflet, the valve may be stiff (unable to open or close properly) or leaky (not able close tightly).

Acquired valve disease. This includes problems that develop with valves that were once normal. These may involve changes in the structure or your valve due to a variety of diseases or infections, including rheumatic fever or endocarditis.

Rheumatic fever is caused by an untreated bacterial infection (usually strep throat). Luckily, the introduction of antibiotics to treat this infection has dramatically reduced the numbers of this infection. The initial infection usually occurs in children, but the heart problems associated with the infection may not be seen until 20-40 years later. At that time, the heart valves become inflamed, the leaflets stick together and become scarred, rigid, thickened, and shortened. This leads to mitral regurgitation. Mitral stenosis is rarely seen in the U.S. outside the immigrant population.

Endocarditis occurs when germs, especially bacteria, enter the bloodstream and attack the heart valves, causing growths and holes in the valves and scarring. This can lead to leaky valves. The germs that cause endocarditis enter the blood during dental procedures, surgery, IV drug use, or with severe infections. People with valve disease (except mitral valve prolapse without thickening or regurgitation/leaking) are at increased risk for developing this life-threatening infection.

There are many changes that can occur to the valves of the heart. The chordae tendinae or papillary muscles can stretch or tear; the annulus of the valve can dilate (become wide); or the valve leaflets can become fibrotic (stiff) and calcified.

Mitral valve prolapse (MVP) is a very common condition, affecting 1 to 2 percent of the population. MVP causes the leaflets of the mitral valve to flop back into the left atrium during the heart's contraction. MVP also causes the tissues of the valve to become abnormal and stretchy, causing the valve to leak. The condition rarely causes symptoms and usually doesn't require treatment.

Other causes of valve disease include: coronary artery disease, heart attack, cardiomyopathy (heart muscle disease), syphilis (a sexually transmitted disease), high blood pressure, aortic aneurysms, and connective tissue diseases. Less common causes of valve disease include tumors, some types of drugs, and radiation.