How is mitral valve prolapse (MVP) diagnosed?

Randolph P. Martin, MD
Cardiology (Cardiovascular Disease)
Mitral valve prolapse is a condition where one of the heart valves, the mitral valve, is actually too long or too thick and, hence, it prolapses, or falls back into the receiving chamber of the left atrium. Think of the mitral valve as having a front and back leaflet and, as mentioned, it sits between the receiving chamber of the heart on the left side, the left atrium that gets oxygenated blood back into the heart from the lungs and the pumping chamber, or the left ventricle. Normally, as the heart fills, the mitral valve opens, and then as the heart contracts, or sends blood to the body, the valve should shut snugly. In mitral valve prolapse, the leaflets may be elongated and thickened and actually, instead of meeting firmly, they tend to meet and then fall back into the receiving chamber. This is analogous to a sail on a sailboat being too large for the mast. Oftentimes, as the valves are closing shut and falling, or prolapsing back into the left atrium, they can create abnormal sounds that your doctor may hear with a stethoscope. Specifically, he or she may hear clicks and/or a murmur, or an unusual flow of blood heard during the pumping phase of the heart called systole. These sounds can come and go though, and hence you may have mitral valve prolapse without your doctor being able to hear the click and murmur. If your doctor is suspicious though, they will order an echocardiogram, which is a noninvasive ultrasound test, similar to ultrasound that is used on women during pregnancy to take pictures of their babies. The echocardiogram is a simple test that allows doctors to look at the size, shape, and pumping action of the heart chambers, as well as to look at the structure of the valve. Fine detail of the mitral valve can be seen and the diagnosis of mitral valve prolapse can often be made. Additionally, the echo can include something called "Doppler echocardiography," whereby the leaking of blood, the blood that is flowing back into the left atrium as the valve prolapses, can actually be seen and quantified.
The mitral valve separates the left upper chamber (atrium) from the left lower chamber (ventricle) of the heart. It is a valve consisting of two leaflets. Mitral valve prolapse is a condition where the leaflets of the valve do not perfectly seal resulting in protrusion of one or both of the leaflets into the left atrium. This happens during the systole of the heart and may cause blood to return to the left atrium. This condition can be diagnosed by a doctor listening to the heart with a stethoscope. If the condition is present the doctor will listen a clicking sound (mid-systolic click). After this click a murmur may be present if the prolapse is significant enough to cause return (regurgitation) of blood to the left atrium. This is called a mid- to late crescendo systolic murmur and its name derives from the increase in its loudness. Mitral valve prolapse can definately be evaluated by echocardiography where the protrusion of the leaflet of the mitral valve and the return (regurgitation) of blood can be visualized.  
A mitral valve prolapse (MVP) most often is found during a routine physical exam when your doctor uses a stethoscope to listen to your heart.
Your doctor listens for a certain "click" and/or murmur. Stretched valve flaps, as seen in MVP, can make a clicking sound as they shut. If the valve is leaking blood back into the atrium, a murmur or whooshing sound often can be heard.
However, these abnormal heart sounds may come and go. Thus, your doctor may not hear them at the time of an exam, even if you have MVP. As a result, you also may have diagnostic tests and procedures to diagnose MVP.
Diagnostic Tests and Procedures
Echocardiography (echo) is the most useful test for diagnosing MVP. This painless test uses sound waves to create a moving picture of your heart. An echo provides information about the size and shape of your heart and how well your heart chambers and valves are working.
The test also can identify areas of heart muscle that aren't contracting normally due to poor blood flow or injury to the heart muscle. In MVP, an echo is used to look for prolapse of the mitral valve flaps and for backflow of blood through the leaky valve.
There are several types of echo, including a stress echo. A stress echo is done before and after a stress test. During a stress test, you exercise or take medicine (given by your doctor) to make your heart work hard and beat fast.
Doppler Ultrasound
A Doppler ultrasound is part of an echo test. A Doppler ultrasound is used to show the speed and direction of blood flow through the mitral valve.
Other Tests
Other tests that can help diagnose MVP are:
  • A chest x ray. This test is used to look for fluid in your lungs or to see whether your heart is enlarged.
  • An EKG (electrocardiogram). An EKG is a simple test that records your heart's electrical activity. An EKG can show how fast your heart is beating, whether its rhythm is steady or irregular, and the strength and timing of electrical signals as they pass through your heart.
This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.

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