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What is mitral valve stenosis?

The mitral valve plays a key role in the functioning of the heart. This one-way valve helps move oxygenated (red) blood from the left atrium into the left ventricle, which then pushes the blood out to the body. If the mitral valve is too narrow — a condition called mitral valve stenosis — blood backs up in the left atrium, with several upstream effects.

  • Added pressure in the left atrium can cause the heart to enlarge and even cause arrhythmias.
  • Because the lungs feed oxygenated blood into the left atrium, the pressure can push blood back into the vessels of the lungs, causing pulmonary hypertension.
  • Because it has to work harder, the heart can weaken over time.

Children with mitral valve stenosis can have increased respiratory symptoms, shortness of breath and difficulty with exercise. Learn more about the symptoms and causes of mitral valve stenosis.

How we care for mitral valve stenosis

The Boston Children’s Hospital Congenital Heart Valve Program team has extensive experience treating mitral valve stenosis in children, adolescents and adults. Our specialized training and experience mean that we understand the unique challenges, circumstances and intricacies of working with young people who have mitral valve stenosis and other heart problems.

Our areas of innovation for mitral valve stenosis

Boston Children’s continues to innovate by offering mitral valve repairs and replacement to even the youngest and smallest children with exceptional results. In addition, we’ve developed a groundbreaking approach to valve replacement in small children using the Melody® Transcatheter Pulmonary Valve, and with catheter-balloon interventions the valve can grow with the baby.

Mitral Valve Stenosis | Symptoms & Causes

What are the symptoms of mitral stenosis?

Many children with mitral valve stenosis show no outward signs, since they are in the mild to moderate stages of the condition and their symptoms have not yet progressed to a more serious level. The only identifiable symptoms, in most cases, are rapid breathing, slow growth/weight gain or a soft heart murmur.

As mitral valve stenosis progresses, children may show more symptoms:

  • rapid or labored breathing
  • frequent coughing or wheezing
  • slow growth/weight gain
  • feeding difficulties
  • fatigue
  • frequent respiratory infections
  • irregular heartbeats or heart palpitations
  • chest pain
  • difficulty exercising

You should seek treatment from a qualified medical professional right away if you notice any of these warning signs in your child.

What is the cause of mitral stenosis?

Often, mitral valve stenosis is caused by a heart defect present at birth. Children can also develop mitral stenosis as a complication of rheumatic fever, though the disease is rare in the U.S. Children with more advanced mitral stenosis are likely to require interventional catheterization or valve surgery; however, some don’t need any immediate treatment. Many children do very well for a long time with regular monitoring by their treatment team.

Mitral valve stenosis can affect each child differently. Your physician is the best resource for providing detailed information about your child’s individual situation and making recommendations about the treatment plan that best meets the needs of your child and your entire family.

Mitral Valve Stenosis | Diagnosis & Treatments

How is mitral valve stenosis diagnosed?

The process of arriving at a diagnosis of mitral valve stenosis usually involves several steps. Often, a clinician will first notice that your child has a heart murmur.

An echocardiogram (cardiac ultrasound) is the definitive test used to confirm the diagnosis. Other tests your child’s clinician might order to make, or rule out, a diagnosis of mitral valve stenosis can include:

How is mitral valve stenosis treated?

Routine monitoring

Children with mild to moderate mitral valve stenosis may not need any treatment other than routine monitoring, as long as they are displaying no outward symptoms and their daily lives are not affected by the condition.

Your child's cardiologist will regularly evaluate your child for any sign of further narrowing in the mitral valve and related complications. Most often, routine monitoring will involve physical examinations and echocardiograms.


Medication is not a cure for mitral valve stenosis but can be helpful in managing specific symptoms. In some cases, your child's clinician may prescribe medication to:

  • help the heart maintain healthy function and blood flow
  • control blood pressure
  • prevent abnormal heart rhythms, called arrhythmias

A child with mitral valve stenosis may also need to periodically take antibiotics in order to prevent an infection called bacterial endocarditis, even if the valve has been surgically replaced. Bacterial endocarditis can cause serious damage to the inner lining of the heart and its valves. Always let medical personnel know about your child's mitral valve stenosis before making arrangements for a medical procedure, even if the procedure seems minor or unrelated to your child's cardiac care.

Interventional catheterization/balloon valvuloplasty

Boston Children's Hospital has a program dedicated to interventional catheterization, the use of a thin tube called a catheter that is threaded from a vein or artery into the heart. We consider interventional catheterization the preferred way (vs. surgery) to treat children with mitral valve stenosis.

The most common interventional catheterization procedure used to treat mitral valve stenosis is balloon dilation or balloon valvuloplasty. With the child under general anesthesia, a small, flexible catheter is inserted into a blood vessel, most often in the groin. Using tiny, highly precise cameras and tools, clinicians guide the catheter up into the inside of the heart and across the mitral valve. A deflated balloon at the tip of the catheter is inflated once the tube is in place, and this balloon stretches the mitral valve open, reversing the problematic narrowing.

Valve-replacement surgery

For children with severe mitral stenosis, balloon valvuloplasty may not adequately fix the narrowed valve. In other cases, as a child grows, a mitral valve that was previously treated successfully with one or more balloon dilation procedures begins to narrow again, adding strain to the heart and affecting blood flow throughout the body. Repair of replacement of the mitral valve is the next step in treatment for these children.

If valve repair is not possible, cardiac surgeons will remove the damaged mitral valve and replace it with either:

  • a mechanical valve
  • a donor valve taken from a human or animal donor (sometimes, new valves can even be fashioned from the child's own tissue)

What is the long-term outlook for mitral valve stenosis?

Both types of valve-replacement surgery have an excellent success rate and a low incidence of complications. Children who have either procedure are likely to enjoy normal, healthy lives with minimal to no restrictions when playing sports or engaging in other strenuous activities.

Mitral Valve Stenosis | Programs & Services