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Aortic stenosis
is a narrowing of the aortic valve opening that increases resistance
to blood flow from the left ventricle to the aorta.
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).
Cause
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 produce 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 younger people, 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 Birth Defects: 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
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 lightheadedness) or with any symptoms after awakening.
Doctors usually base the diagnosis on a characteristic heart murmur heard through a stethoscope, on pulse abnormalities, and on results of electrocardiography (ECG) indicating thickening of the heart wall. For people who experience angina, shortness of breath, or faintness, echocardiography (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Echocardiography and Other Ultrasound Procedures) 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. Cardiac catheterization (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Cardiac Catheterization and Coronary Angiography) is usually necessary as the doctor is not sure 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 performed 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 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 performed 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 valvuloplasty. In balloon valvuloplasty, a balloon-tipped catheter is threaded through a vein and eventually into the heart (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: 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, stenosis always recurs after balloon valvuloplasty; so among adults, this procedure is used only for frail older people who cannot tolerate surgery.
Last full review/revision May 2006 by Paul H. Tanser, MD
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