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Aortic Stenosis

by Guy P. Armstrong, MD

Aortic stenosis is a narrowing of the aortic valve opening that slows blood flow from the left ventricle to the aorta.

  • The most common cause in people younger than 70 is a congenital abnormality of the valve. In people over 70, the most common cause is aortic sclerosis.

  • People may have chest pain, feel short of breath, or faint.

  • Doctors usually base the diagnosis on a characteristic heart murmur heard through a stethoscope, on pulse abnormalities, and on results of echocardiography.

  • People see their doctors regularly so their condition can be monitored, and people with symptoms may undergo surgical replacement of the valve.

In aortic stenosis, the wall of the left ventricle usually thickens because the ventricle must work harder to pump blood through the narrowed valve opening into the aorta. The thickened heart muscle requires an increasing supply of blood from the coronary arteries, and sometimes, especially during exercise, the blood supply does not meet the needs of the heart muscle, and chest pain, fainting, and sometimes sudden death may occur. The heart muscle may also begin to weaken, leading to heart failure. The abnormal aortic valve can rarely become infected by bacteria (infective endocarditis).

Causes

In North America, Australasia, and Western Europe, aortic stenosis is mainly a disease of older people—the result of scarring and calcium accumulation (calcification) in the valve cusps. In such cases, aortic stenosis begins after age 60 but does not usually cause symptoms until age 70 or 80. Aortic stenosis may also result from rheumatic fever contracted in childhood. When rheumatic fever is the cause, aortic stenosis is usually accompanied by mitral stenosis, leakage (regurgitation), or both.

In people under 70, the most common cause is a birth defect, such as a valve with only two cusps instead of the usual three or a valve with an abnormal funnel shape (see Aortic Valve Stenosis). The narrowed aortic valve opening may not be a problem in infancy, but problems occur as a person grows. The valve opening remains the same size, but the heart grows and enlarges further as it tries to pump increasing amounts of blood through the small valve opening. Over the years, the opening of a defective valve often becomes stiff and narrow because calcium accumulates.

Symptoms and Diagnosis

People who develop aortic stenosis as a result of a birth defect may not develop symptoms until adulthood.

Chest pain (angina) may occur during exertion. This pain goes away with several minutes of rest. People with heart failure develop fatigue and shortness of breath during exertion.

People who have severe aortic stenosis may faint during exertion because blood pressure may fall suddenly. Fainting usually occurs without any warning symptoms (such as dizziness or light-headedness).

Doctors usually base the diagnosis on a characteristic heart murmur heard through a stethoscope and on results of echocardiography (see Echocardiography and Other Ultrasound Procedures). Echocardiography is the best procedure for assessing the severity of aortic stenosis (by measuring how small the valve opening is) and the function of the left ventricle.

For people who have aortic stenosis but do not have symptoms, doctors often do a stress test (see Stress Testing). People who experience angina, shortness of breath, or faintness during the stress test are at risk of complications and may need treatment.

Cardiac catheterization (see Cardiac catheterization) is usually necessary to determine whether the person also has coronary artery disease.

Treatment

Adults who have aortic stenosis but no symptoms should see their doctor regularly and should avoid overly stressful exercise. Echocardiography is done periodically to monitor heart and valve function.

In adults who have aortic stenosis that causes shortness of breath on exertion, angina, or fainting, the aortic valve is surgically replaced, preferably before the left ventricle is irreversibly damaged. Echocardiography, usually performed periodically, can help doctors determine when to schedule surgery. Surgical replacement of the abnormal valve is the best treatment for adults of all ages, and the prognosis after valve replacement is excellent.

Before surgery, heart failure is treated with diuretics (see Some Drugs Used to Treat Heart Failure). Treating angina is often difficult, because nitroglycerin, which is used to treat angina in people who have coronary artery disease, can rarely cause dangerously low blood pressure and worsen the angina in people with aortic stenosis.

People with an artificial valve must take antibiotics before a surgical, dental, or medical procedure (see Table: Which Procedures Require Preventive Antibiotics*?) to reduce the risk of an infection on the valve (infective endocarditis).

For children who have severe stenosis, surgery may be done even before symptoms develop, because sudden death may occur before symptoms develop. Safe, effective alternatives to valve replacement are surgical repair of the valve and balloon valvotomy. In balloon valvotomy, a balloon-tipped catheter is threaded through a vein and eventually into the heart (see Cardiac catheterization). Once inside the valve, the balloon is inflated to expand the valve opening. However, later, when children are fully grown, the valve usually must be replaced. In adults, repeat stenosis always recurs after balloon valvotomy. So among adults, this procedure is used only for frail older people who cannot tolerate surgery. A new technique is being developed in which the valve can be replaced through a catheter threaded up the femoral artery (rather than via surgery). At present, this transcatheter aortic valve implantation (TAVI) procedure appears better than medical therapy and about equivalent to surgical replacement, although increased rates of stroke occur.

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