Heart Disease Health Center

What is mitral valve stenosis?

Mitral valve stenosis is a heart problem in which the mitral valve doesn't open as wide as it should. It is a lifelong disease.

When you first develop it, you most likely have no symptoms and notice no change in your health. Symptoms develop over 10 to 20 years or more. Mitral valve stenosis can lead to heart failure, a stroke, an infection in the heart (endocarditis), or a fast, slow, or uneven heartbeat (arrhythmia).

How does the mitral valve work?

Your heart has four chambers and four valves. The valves have flaps, or leaflets. The flaps open and close to keep blood flowing in the proper direction through your heart.

The mitral valve connects the heart's upper-left chamber (left atrium) to the lower-left chamber (left ventricle). When the heart pumps, blood forces the flaps open, and blood flows from the left atrium to the left ventricle. Between heartbeats, the flaps close tightly so that blood does not leak backward through the valve.

See a picture of the heart and its chambers, valves, and blood flow .

See a picture of an open and closed mitral valve .

With mitral valve stenosis, the mitral valve becomes stiff or scarred, or the valve flaps become partially joined together. The valve doesn't open as widely as it should. As a result, not as much blood can flow into the left ventricle. More blood stays in the left atrium, and blood may back up into the lungs.

See a picture of mitral valve stenosis .

What causes mitral valve stenosis?

Nearly all cases of mitral valve stenosis are caused by rheumatic fever. This fever results from an untreated strep infection, most often strep throat. But many people who have mitral valve stenosis don't realize they had rheumatic fever.

What are the symptoms?

Symptoms do not usually develop for 10 to 20 years after stenosis starts, and they may take as long as 40 years to develop. After you develop symptoms, they may not become severe for another 3 to 10 years.

When symptoms first appear, they usually are mild. You may only have a few symptoms, even if your mitral valve is very narrow. An early symptom is shortness of breath when you are active. This shortness of breath may seem normal to you.

Later in the disease, symptoms may include:

• Shortness of breath even when you have not been very active or when you are resting.
• Feeling very tired or weak.
• Pounding of the heart (palpitations).

Call your doctor if your symptoms get worse or you have new symptoms.

How is mitral valve stenosis diagnosed?

Mitral valve stenosis may not be diagnosed until you've had the disease for some time. If you don't have symptoms, the first clue might be a heart murmur your doctor hears during a routine checkup.