Mitral (MI-tral) valve prolapse (MVP) is a condition in which the heart's mitral valve doesn't work well. The flaps of the valve are "floppy" and don't close tightly. These flaps normally help seal or open the valve.
Much of the time, MVP doesn't cause any problems. Rarely, blood can leak the wrong way through the floppy valve. This can lead to palpitations, shortness of breath, chest pain, and other symptoms. (Palpitations are feelings that your heart is skipping a beat, fluttering, or beating too hard or too fast.)
Normal Mitral Valve
The mitral valve controls blood flow between the upper and lower chambers of the left side of the heart. The upper chamber is called the left atrium (AY-tree-um). The lower chamber is called the left ventricle (VEN-trih-kul).
The mitral valve allows blood to flow from the left atrium into the left ventricle, but not back the other way. The heart also has a right atrium and ventricle, separated by the tricuspid (tri-CUSS-pid) valve.
With each heartbeat, the atria contract and push blood into the ventricles. The flaps of the mitral and tricuspid valves open to let blood through. Then, the ventricles contract to pump the blood out of the heart.
When the ventricles contract, the flaps of the mitral and tricuspid valves close. They form a tight seal that prevents blood from flowing back into the atria.
For more information, go to the Health Topics How the Heart Works article. This article contains animations that show how your heart pumps blood and how your heart's electrical system works.
Mitral Valve Prolapse
In MVP, when the left ventricle contracts, one or both flaps of the mitral valve flop or bulge back (prolapse) into the left atrium. This can prevent the valve from forming a tight seal.
As a result, blood may leak from the ventricle back into the atrium. The backflow of blood is called regurgitation (re-GUR-jih-TA-shun).
MVP doesn't always cause backflow. In fact, most people who have MVP don't have backflow and never have any related symptoms or problems. Their mitral valves still can form a tight seal.
When backflow does occur, it can cause shortness of breath, irregular heartbeats called arrhythmias (ah-RITH-me-ahs), or chest pain.
Mitral Valve Prolapse
Figure A shows a normal mitral valve. The valve separates the left atrium from the left ventricle. Figure B shows a heart with mitral valve prolapse. Figure C shows a closeup view of mitral valve prolapse. Figure D shows a mitral valve that allows blood to flow back into the left atrium.
Backflow can get worse over time. It can change the heart's size and raise pressure in the left atrium and lungs. Backflow also raises the risk of heart valve infections.
Medicines can treat troublesome MVP symptoms and help prevent complications. Some people will need surgery to repair or replace their mitral valves.
MVP once was thought to affect as much as 5 to 15 percent of the population. Researchers now believe that many people who were diagnosed with MVP in the past didn't actually have a faulty mitral valve.
They may have had a slight bulging of the valve flaps due to other conditions, such as dehydration (lack of fluid in the body) or a small heart. However, their valves were normal, and little or no backflow of blood occurred.
Diagnosing MVP is more precise now because of a test called echocardiography (EK-o-kar-de-OG-ra-fee). This test allows doctors to easily see MVP and detect troublesome backflow.
As a result, researchers now think that less than 3 percent of the population actually has MVP. They believe an even smaller percentage has serious complications from the condition.
Most people who have MVP have no symptoms or medical problems and don't need treatment. They're able to lead normal, active lives; they may not even know they have the condition.
A small number of people who have MVP may need medicine to relieve their symptoms. Very few people who have MVP need heart valve surgery to repair their mitral valves.
Rarely, MVP can cause problems such as arrhythmias (irregular heartbeats) or infective endocarditis (EN-do-kar-DI-tis). Endocarditis is an infection of the inner lining of the heart chambers and valves. Bacteria that enter the bloodstream can cause the infection.