Blood that flows between different chambers of your heart must flow through a valve. The valve between the two chambers on the left side of your heart is called the mitral valve. It opens up enough so that blood can flow from the upper chamber of your heart (left atria) to the lower chamber (left ventricle). It then closes, keeping blood from flowing backwards.
Mitral stenosis means that the valve cannot open enough. As a result, less blood flows to the body. The upper heart chamber swells as pressure builds up. Blood and fluid may then collect in the lung tissue (pulmonary edema), making it hard to breathe.
In adults, mitral stenosis occurs most often in people who have had rheumatic fever. This is a disease that can develop after an illness with strep throat that was not properly treated.
The valve problems develop 5 - 10 years or more after having rheumatic fever. Symptoms may not show up for even longer. Rheumatic fever is becoming rare in the United States because strep infections are most often treated. This has made mitral stenosis less common.
Rarely, other factors can cause mitral stenosis in adults. These include:
- Calcium deposits forming around the mitral valve
- Radiation treatment to the chest
- Some medications
Children may be born with mitral stenosis (congenital) or other birth defects involving the heart that cause mitral stenosis. Often, there are other heart defects present along with the mitral stenosis.
Mitral stenosis may run in families.