Mitral Valve Regurgitation

What is mitral valve regurgitation?

The mitral valve lies on the left side of the heart between the left upper chamber (atrium) and lower chamber (ventricle). The valve has two flaps called leaflets that normally close every time the ventricle squeezes to pump blood out of the heart. A number of things may keep the valve from closing properly. When the mitral valve does not close properly, some of the blood from the ventricle is forced back up (regurgitated) into the left atrium instead of flowing out to the rest of the body. The added workload on the heart and the increased blood pressure in the lungs may eventually cause problems.

How does it occur?

Rheumatic fever can damage valve leaflets and cause scarring. The scars deform the leaflets so that they do not close properly. Mitral valve prolapse, a different type of deformity of the leaflets, is a result of stretching of the leaflets and their cordlike attachments to the heart muscle. Mitral valve prolapse causes one or both leaflets to bulge into the atrium when the heart contracts. A small amount of mitral regurgitation (MR) is common with mitral valve prolapse.

If one or more of the cordlike structures attaching the leaflets to the heart muscle breaks, the valve may leak. Heart attacks, diseases of the heart muscle, or other heart valve abnormalities may cause the whole heart to enlarge. The enlargement stretches the mitral valve ring and muscular attachments, pulling the valve leaflets apart. When the leaflets no longer meet, leaking of the mitral valve (mitral regurgitation) results.

What are the symptoms?

People with mild to moderate MR may have no symptoms. Over time, the added workload on the heart may cause shortness of breath with exercise or congestive heart failure. Congestive heart failure occurs when the heart cannot pump enough blood to keep the lungs or other body tissues from filling with fluid. The MR may cause both the left ventricle and left atrium to get larger. If the left atrium becomes big enough, an irregular heart rhythm called atrial fibrillation may result. This abnormal rhythm may cause palpitations, which feel like your heart is pounding, racing, or skipping in your chest.

If a valve leaflet cord breaks, the sudden MR may quickly cause shortness of breath or congestive heart failure.

How is it diagnosed?

Most MR causes a heart murmur that can be heard through a stethoscope and is quite easily recognized. Enlargement of the heart may be discovered during a physical examination.

The echocardiogram uses ultrasound waves to make pictures of the heart. The pictures show the size of the heart chambers, the thickness of the heart muscle, and the movement of the heart valves. Doppler echo is a special kind of ultrasound that shows the backflow of blood through a valve. The echocardiogram can measure the amount of MR.

How is it treated?

If you have MR with a normal-sized heart and no symptoms, you need no treatment except for antibiotics before having dental work. The antibiotics prevent infections from starting on the mitral valve. Moderate to severe MR eventually results in heart enlargement and symptoms. Most people with symptoms will need valve repair or replacement. If you delay treatment for too long, your heart muscle may already be seriously damaged and repair of the valve may be less successful.

The best treatments are surgical. Surgeons prefer to repair the existing valve by narrowing the valve ring and tailoring the valve leaflets. A plastic support ring is stitched around the valve to bring the leaflets closer together. An advantage of this kind of surgery is that long-term use of blood-thinning drugs is not needed.

Sometimes the mitral valve leaflets are damaged so badly that they must be replaced. Artificial heart valves made of human or pig tissue work well but may need to be replaced in about 10 years. They don’t require long-term blood thinners after surgery. Artificial mechanical valves also work very well. These valves last longer without wearing out, but blood thinners must be taken for life.

Other than surgery, drugs that expand (dilate) blood vessels and slightly lower blood pressure are the only medicines known to be helpful in treating MR. They work best for those who are very ill, making them feel better. Though the drugs work well at first, they do not seem to be the answer for the long term.

What are the complications of treatment?

Most complications occur when mechanical valves are used to replace the mitral valve. Recurrent blood clots may form on the valve and become a problem. Small clots can break away and sometimes cause strokes. Blood-thinning drugs are necessary to prevent these clots. However, blood thinners may lead to serious bleeding from other parts of your body if not taken correctly. Your health care provider will carefully supervise the dose of blood thinners you take.

Information obtained from GE Medical Systems; authorization given to reproduce on HCNW web site 9/02.
Developed by Donald L. Warkentin, MD; Phyllis G. Cooper, RN, MN; and McKesson Clinical Reference Systems.
Published by McKesson Clinical Reference Systems.
Copyright 1991-2002 McKesson Health Solutions LLC. All rights reserved.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.