Introduction

Heart valves control blood flow through the four chambers of the heart. A heart valve consists of an opening guarded by flaps (cusps or leaflets). The leaflets of each valve open and close like one-way swinging doors to make sure that blood flows in only one direction. A heart valve disorder may involve narrowing (stenosis) of a valve's opening, interfering with blood flow through the valve. Or a heart valve disorder may involve backward leakage (regurgitation) of blood through a valve. Stenosis and regurgitation may affect the same valve.

See the figure Understanding Stenosis and Regurgitation.

The more severe the narrowing or leakage becomes, the harder the heart has to work and the more likely symptoms are to occur. If heart valve disorders are not diagnosed and treated, blood pressure may increase. Or blood may begin to back up in the heart, and the heart may become unable to pump enough blood to the body. Serious disorders such as heart failure, stroke, abnormal heart rhythms (arrhythmias), and infection of the heart valves (endocarditis) can result.

A heart valve disorder can develop in any of the four heart valves (mitral, aortic, tricuspid, or pulmonary valves). The mitral valve controls blood flow from the left upper chamber of the heart (atrium) to the left lower chamber (ventricle). The aortic valve controls blood flow from the left ventricle into the aorta, the artery that carries oxygen-rich blood to the body. The tricuspid valve controls blood flow from the right atrium into the right ventricle. The pulmonary (pulmonic) valve controls blood flow from the right ventricle into the arteries that carry blood to the lungs (pulmonary arteries). Among older people, disorders of the aortic valve and the mitral valve are the most common.

Causes

Among older people, several disorders can cause heart valves to malfunction. Calcium may accumulate in a valve (a disorder called degenerative calcification). This disorder affects about one third of people over 70. Certain hereditary disorders can cause the valves to deteriorate over time. The most common one, myxomatous degeneration, can cause the valves to become floppy and thus leak. A valve may be defective at birth. Such a valve may deteriorate, sometimes not causing symptoms until late in life. A heart attack or an infection of the heart valve may damage the structures that support the valve. Leakage may result. Less commonly, a heart valve disorder may be caused by rheumatic fever (a now rare childhood illness that can develop after strep throat if it is not treated).

Symptoms

Symptoms vary depending on which valve is malfunctioning, how quickly the disorder develops, and whether the valve is narrowed or leaking. Some heart valve disorders cause few or no symptoms. Some cause severe symptoms that occur suddenly.

The most common symptom is shortness of breath during physical activity. Shortness of breath usually occurs because the heart has to work harder to pump the same amount of blood. And during physical activity, the heart is already working harder because the heart needs more oxygen. Chest pain may occur if the heart does not get enough oxygen. Lack of oxygen may damage the heart. The damage may prevent the heart from pumping enough blood for the body's needs.

Some people with a heart valve disorder feel their heart beating rapidly and irregularly (a feeling called palpitations). They may feel weak or faint. These symptoms may be due to an abnormal heart rhythm called atrial fibrillation. Atrial fibrillation may develop when blood backs up in and stretches the left atrium, causing the heart to enlarge.

If a heart valve disorder worsens, people may also feel short of breath during rest. This symptom indicates that heart failure is developing. Heart failure develops as the heart works harder and harder to pump blood to the rest of the body. At first, as the heart tries to pump harder, its walls thicken and its chambers enlarge. But eventually, the heart cannot keep up with the extra work. Then blood backs up in the veins that carry blood to the left atrium from the lungs. Pressure in the blood vessels of the lungs increases. Fluid may leak out of blood vessels and accumulate in the lungs, interfering with breathing.

Blood clots tend to form when blood backs up in the atrium. Clots do not cause symptoms unless part of the clot breaks off, travels through the bloodstream, and blocks an artery elsewhere in the body. If an artery that carries blood to the brain is blocked, a stroke may result.

Diagnosis

Heart valve disorders are often first suspected during a routine physical examination. Doctors may detect abnormal heart sounds (murmurs) when they use a stethoscope to listen to the heart. Heart murmurs occur because blood does not flow through the valve normally. The pulse may be fast and irregular. A chest x-ray may show an enlarged heart.

Echocardiography (ultrasonography of the heart) is an accurate way to detect a heart valve disorder. This test helps doctors confirm the diagnosis and determine which heart valve disorder is present and how severe it is. Echocardiography can also detect evidence of heart damage, such as weak pumping of the heart. For the procedure, a handheld device that emits and records ultrasound waves is placed on the chest. This procedure is safe and painless. If a closer look at the heart is needed, an ultrasound device is passed down the throat into the esophagus. This method (called transesophageal echocardiography) is safe but sometimes causes gagging and anxiety. So before the procedure, doctors usually give people a drug to calm them.

Treatment

For many older people with a heart valve disorder, drugs are effective. The drugs used depend on the type of disorder.

Antihypertensive drugs may be used. These drugs are typically used to lower blood pressure. However, they are also used to treat some heart valve disorders because these drugs reduce the amount of work the heart has to do. Two types of antihypertensive drugs—calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors—reduce the heart's workload by causing arteries to widen (dilate).

Beta-blockers (another type of antihypertensive drug) are used to treat some heart valve disorders. Beta-blockers slow the heart rate so that the blood has more time to flow through the narrowed valve opening. These drugs lessen palpitations and other symptoms.

People who also have atrial fibrillation may be given digoxin (commonly used to treat heart failure). This drug slows the heart rate when it is too rapid.

If the left atrium is stretched and enlarged, warfarin (an anticoagulant) is used to prevent clots from forming. However, warfarin increases the risk of bleeding, especially for older people. For example, minor bumps may cause bleeding under the skin (bruises), cuts may bleed longer, and bleeding after surgery or an injury may be excessive. To keep this risk as low as possible, doctors instruct a person to periodically have blood tests that measure how long blood takes to clot. The dose of warfarin can be adjusted based on the test results. Warfarin is not given to people who have bleeding disorders. It may not be given to people who are at high risk of falling.

If symptoms of heart failure develop, diuretics are sometimes used. They increase the amount of fluid and salt excreted by the kidneys. However, doctors carefully adjust the dose and monitor the use of these drugs because symptoms may worsen if the kidneys excrete too much fluid.

If symptoms develop or if tests detect permanent heart damage, repair or replacement of the valve may be recommended. Age does not affect the decision to perform such a procedure. However, the presence of other disorders and the person's overall condition (for example, being very frail) may make a procedure inadvisable.

See the figure Replacing a Heart Valve.

If possible, the abnormal valve is repaired. In one type of repair, excess valve tissue is removed, and a supporting ring is implanted. If an abnormal valve cannot be repaired, it is replaced with a metal (mechanical) valve or a valve made of pig, cow, or human tissue.

Heart valve repair or replacement is very effective. Symptoms may resolve, often completely, and life can often be prolonged. Valve repair or replacement usually requires open-heart surgery. Sometimes new techniques using a small incision can be used. These techniques result in fewer problems, and recovery may be faster. Having a kidney or lung disorder or another heart disorder makes valve replacement riskier.

Risks of valve repair or replacement include breathing problems, abnormal heart rhythms, bleeding, stroke, and death. The risks are higher for older people but are usually less than the risks of not having the valve repaired or replaced.

People who have a heart valve disorder or who have had a heart valve replaced must take antibiotics before certain surgical, dental, or medical procedures. This precaution helps prevent endocarditis. Such people should talk with their doctor about what their risk of developing endocarditis is, what to do to prevent it, and what its early symptoms are.

Outlook

Sometimes heart valve disorders are mild, require no treatment, and do not shorten life. In other cases, drugs or surgery can effectively control symptoms or even cure the disorder. But having another chronic disorder may make the outlook worse or may even make treatment of a heart valve disorder inadvisable. Then, life may be shortened, and the focus shifts to improving quality of life and relieving symptoms.

For people with a heart valve disorder, death is often due to heart failure or an abnormal heart rhythm. In either case, death may occur without warning. Consequently, preparing advance directives is important.

See the sidebar Operating on the Heart: Open-Heart Surgery.