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Quick Facts

Mitral Stenosis


The Manual's Editorial Staff

Last full review/revision Feb 2021| Content last modified Feb 2021
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What is mitral stenosis?

Four heart valves control how blood flows in and out of your heart. The valves are like one-way doors that keep blood flowing in the right direction.

Your mitral valve separates your left atrium and left ventricle. This valve opens to let blood from your lungs out of your left atrium and into the left ventricle. The valve closes to keep blood from running back into your left atrium.

Mitral stenosis is when the mitral valve doesn't open all the way so it's hard for blood from your lungs to get out of the left atrium. Blood pressure in your left atrium and your lungs builds up.

  • Certain disorders can cause the flaps on the mitral valve to get stiff and thick

  • The most common cause is untreated rheumatic fever, but infants can be born with it

  • Mitral stenosis may not cause symptoms for a long time

  • Severe stenosis can cause symptoms, such as shortness of breath, or an abnormal heart rhythm, such as atrial fibrillation

  • Doctors can hear a heart murmur through a stethoscope and do echocardiography to diagnose mitral stenosis

  • Treatment can include medicines and surgery

Atrial fibrillation can cause problems such as blood clots or stroke. Severe mitral stenosis can cause heart failure (your heart doesn’t pump blood well to the rest of your body).

If you have mitral stenosis, pregnancy can make heart failure develop quickly.

What causes mitral stenosis?

Causes include:

  • Rheumatic fever in childhood—but mitral stenosis will not occur if rheumatic fever is prevented by promptly treating strep throat with antibiotics

  • Wear and tear in the valve with old age

  • Sometimes, people are born with mitral stenosis

What are symptoms of mitral stenosis?

Mild mitral stenosis doesn't usually cause symptoms.

Severe mitral regurgitation can cause heart failure, which may cause you to:

  • Get tired easily

  • Feel short of breath

  • Have swelling in your legs

Atrial fibrillation may cause:

  • Palpitations (feeling your heart pounding, fluttering, racing, or skipping beats)

  • Shortness of breath

Once symptoms start, people become severely disabled in about 7 to 9 years. Children born with mitral stenosis often don’t live more than 2 years unless they have surgery.

How can doctors tell if I have mitral stenosis?

Doctors suspect mitral stenosis by listening to your heart with a stethoscope. Doctors use echocardiography (an ultrasound of your heart) to find out how narrow the valve is.

Doctors also do tests such as:

  • Electrocardiography (ECG/EKG) (a quick, painless, harmless test that measures your heart’s electrical currents and records them on a piece of paper)

How do doctors treat mitral stenosis?

If you don't have symptoms, you don't need treatment.

If you have symptoms, doctors will treat you with medicines to:

  • Make you urinate more and lower the blood pressure in your lungs

  • Control your heart rate

  • Prevent blood clots

If the medicines don't control the symptoms enough, the valve may be repaired or replaced.

When possible, doctors try to repair the valve, a procedure called a valvuloplasty. During valvuloplasty, the doctor inserts a thin, hollow tube (catheter) through a vein or artery into your heart. The doctor inflates a balloon on the tip of the catheter. The balloon pushes the valve open. Sometimes doctors repair the valve during heart surgery.

If your valve cannot be repaired, it can be replaced with:

  • A plastic, mechanical valve

  • A valve from a pig or cow heart (bioprosthetic valve)

If you get a mechanical valve, you'll need to take blood-thinning medicine for the rest of your life, but the valve may last several decades. If you get a bioprosthetic valve, you'll need to take the blood-thinning medicine for only a few months, but the valve will last only 10 to 12 years.

People with damaged or replaced valves sometimes need antibiotics to prevent heart valve infection, such as when they:

  • Get dental work

  • Have certain medical procedures

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