Your heart has four valves that keep blood flowing in the correct direction. These valves include the mitral valve, tricuspid valve, pulmonary valve and aortic valve. Each valve has flaps (cusps or leaflets) that open and close once during each heartbeat. Sometimes, the valves don't open or close properly, disrupting the blood flow through your heart and potentially impairing the ability to pump blood to your body.
In aortic valve stenosis, the aortic valve between the lower left heart chamber (left ventricle) and the main artery that delivers blood from the heart to the body (aorta) is narrowed (stenosis).
When the aortic valve is narrowed, the left ventricle has to work harder to pump a sufficient amount of blood into the aorta and onward to the rest of your body. This can cause the left ventricle to thicken and enlarge. Eventually the extra work of the heart can weaken the left ventricle and your heart overall, and it can ultimately lead to heart failure and other problems.
Aortic valve stenosis can occur due to many causes, including:
Congenital heart defect. The aortic valve consists of three tightly fitting, triangular-shaped flaps of tissue called cusps. Some children are born with an aortic valve that has only two (bicuspid) cusps instead of three. People may also be born with one (unicuspid) or four (quadricuspid) cusps, but these are rare.
This defect may not cause any problems until adulthood, at which time the valve may begin to narrow or leak and may need to be repaired or replaced.
Having a congenitally abnormal aortic valve requires regular evaluation by a doctor to watch for signs of valve problems. In most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented.
Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve calcification). Calcium is a mineral found in your blood. As blood repeatedly flows over the aortic valve, deposits of calcium can build up on the valve's cusps. These calcium deposits aren't linked to taking calcium tablets or drinking calcium-fortified drinks.
These deposits may never cause any problems. However, in some people — particularly those with a congenitally abnormal aortic valve, such as a bicuspid aortic valve — calcium deposits result in stiffening of the cusps of the valve. This stiffening narrows the aortic valve and can occur at a younger age.
However, aortic valve stenosis that is related to increasing age and the buildup of calcium deposits on the aortic valve is most common in older people. It usually doesn't cause symptoms until ages 70 or 80.
Rheumatic fever. A complication of strep throat infection, rheumatic fever may result in scar tissue forming on the aortic valve. Scar tissue alone can narrow the aortic valve and lead to aortic valve stenosis. Scar tissue can also create a rough surface on which calcium deposits can collect, contributing to aortic valve stenosis later in life.
Rheumatic fever may damage more than one heart valve, and in more than one way. A damaged heart valve may not open fully or close fully — or both. While rheumatic fever is rare in the United States, some older adults had rheumatic fever as children.