American Medical Association Family Medical Guide - American Medical Association [347]
Aortic Stenosis
Aortic stenosis occurs when the aortic valve (the valve between the aorta and the left ventricle) becomes abnormally thick or the valve flaps (leaflets) become stuck together, narrowing the opening. The aorta is the artery through which the left ventricle of the heart pumps blood to the body tissues. If the opening becomes narrowed, the volume of blood that the heart can pump decreases. In an effort to squeeze more blood through the valve and keep the volume of blood pumped by the heart normal, the muscular wall of the left ventricle thickens. This thicker, harder-working tissue requires more and more blood to keep working. The blood squirting past the obstructed valve produces a sound called a heart murmur that a doctor can hear through a stethoscope.
Healthy mitral valve
A healthy mitral valve allows oxygen-rich blood to flow from the left atrium into the left ventricle, the main pumping chamber of the heart.
Mitral valve prolapse
In mitral valve prolapse, the valve leaflets can become thickened and elongated and may not close properly, causing blood to leak back into the left atrium from the left ventricle. This condition, called mitral regurgitation or mitral insufficiency, increases the heart’s workload, causing the muscular heart wall and the left atrium to enlarge.
Aortic stenosis
In aortic stenosis, the aortic valve becomes thickened and narrowed, allowing less blood to flow through. Because the left ventricle must then work harder to pump the same volume of blood, the ventricle wall gradually thickens and the ventricle becomes enlarged. Aortic stenosis can lead to irregular heart rhythms, heart failure, or a heart attack.
Symptoms
At first, aortic stenosis may produce no symptoms. However, as the condition worsens, you will become short of breath during and after physical activity. You may experience chest pain or dizziness, or you may faint when you exert yourself. Eventually, you may develop symptoms of congestive heart failure (see page 570) such as swollen ankles, shortness of breath, or fatigue.
Three possible causes of aortic stenosis are a congenital (present at birth) malformation of the valve called congenital aortic stenosis (see page 591), scarring and thickening of the valve that develops with age (called degenerative or calcific aortic stenosis), or narrowing of the valve as a result of rheumatic fever (see page 432). For unknown reasons, men are about three times more likely to develop aortic stenosis than women.
As the workload of the left ventricle increases, the blood supply to the heart muscle is reduced, which can cause chest pain, a heart attack, ventricular fibrillation (see Cardiac Arrest; page 581), or sudden death. Once symptoms develop, the risk of dying increases significantly. About half of people who develop symptoms of aortic stenosis die within 3 years. If you have symptoms of aortic stenosis, see your doctor as soon as possible.
Diagnosis
A doctor can detect aortic stenosis during a routine physical examination. A chest X-ray may show whether your heart is enlarged. An electrocardiogram (ECG; see page 559) can help the doctor determine the source of the problem. A Doppler ultrasound scan (see page 111) can also help the doctor evaluate the stenosis. The diagnosis can be confirmed with cardiac catheterization (see below).
Treatment
If you have mild aortic stenosis, you will need to avoid strenuous activity. Your doctor will probably recommend regular, moderate exercise