To understand the causes of aortic valve stenosis, it may help to know how the heart and heart valves typically work.
The heart has four valves that keep blood flowing in the correct way:
- Aortic valve.
- Mitral valve.
- Tricuspid valve.
- Pulmonary valve.
Each valve has flaps, also called cusps, that open and close once during each heartbeat. Sometimes, the valves don't open or close properly. If a valve doesn't fully open or close, blood flow is reduced or blocked.
In aortic valve stenosis, the valve between the lower left heart chamber, called the left ventricle, and the body's main artery, called the aorta, is narrowed and doesn't open completely. This narrowing is called stenosis.
When the aortic valve opening is narrowed, the heart must work harder to pump enough blood to the body. The extra work can cause the lower left heart chamber to get thick. Eventually the heart may become weak.
Aortic valve stenosis causes include:
- Heart condition present at birth, called a congenital heart defect. Some children are born with an aortic valve that has only two cusps instead of the usual three. If there are only two cusps, it's called a bicuspid aortic valve. Rarely, an aortic valve may have one or four cusps.
- Calcium buildup on the valve, called aortic valve calcification. Calcium is a mineral found in the blood. As blood moves over the aortic valve, calcium can collect on the valve. The calcium deposits may never cause any problems. Aortic valve stenosis that's related to increasing age and calcium deposit buildup usually doesn't cause symptoms until age 70 or 80. But in some people — particularly those with changes in the aortic valve at birth — calcium deposits might cause the valve to narrow at a younger age.
- Rheumatic fever. This complication of untreated strep throat can damage the heart valves. It may cause scar tissue to form on the aortic valve. Scar tissue can narrow the aortic valve opening. It also may make a rough surface on which calcium deposits can collect.