What Is Mitral Valve Prolapse?
Mitral (MI-tral) valve prolapse (MVP) is a condition
in which one of the valves of the heart, the mitral valve, doesnt work
properly. The flaps of the valve are floppy and dont close
tightly. Much of the time, MVP doesnt cause any problems. Rarely, blood
can leak the wrong way through the floppy valve, which may cause shortness of
breath,
palpitations,
chest pain, and other symptoms.
Normal Mitral Valve
The mitral valve controls the flow of blood between
the two chambers on the left side of the heart. The two chambers are the left
atrium (AY-tree-um) and the left ventricle (VEN-trih-kul). The mitral valve
allows blood to flow from the left atrium to 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.)
At the beginning of a heartbeat, the atria contract
and push blood through to the ventricles. The flaps of the mitral and tricuspid
valves swing open to let the 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 swing shut and form a tight seal that prevents
blood from flowing back into the atria.
For more information, see the
How the Heart Works section.
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, which allows
blood to flow backward from the ventricle into the atrium. The backward flow of
blood is called regurgitation (re-GUR-ji-TA-shun), and it can lead to symptoms
and complications.
Regurgitation doesnt occur in all cases of
MVP. In fact, the majority of people with MVP dont have regurgitation and
never have any symptoms or complications. In these people, even though the
valve flaps prolapse, the valve is still able to form a tight seal.
When regurgitation does occur, it can cause
complications and troublesome symptoms such as shortness of breath,
arrhythmias
(ah-RITH-me-ahs), or chest pain. Arrhythmias are problems with the rate or
rhythm of the heartbeat.
Regurgitation can get worse over time and lead to
changes in the hearts size and higher pressures in the left atrium and
lungs. Regurgitation increases the risk for heart valve infections.
Medicines can treat MVP symptoms that cause people
to worry or have discomfort. Medicines are also used to prevent complications.
Sometimes a person will need surgery to repair or replace the mitral valve.
Figure A shows the normal mitral
valve separating the left atrium from the left ventricle. Figure B shows the
heart with mitral valve prolapse. Figure C shows the detail of mitral valve
prolapse. Figure D shows a mitral valve that allows blood to flow backward into
the left atrium.
MVP was once thought to affect as much as 5 to 15
percent of the population. Its now believed that many people who were
diagnosed with MVP in the past didnt actually have an abnormal mitral
valve. They may have had a slight bulging of the valve flaps due to other
conditions such as dehydration or a small heart. However, their valve was
normal and there was little or no regurgitation through the valve.
Now, more precise rules for diagnosing MVP with a
test called an
echocardiogram make it easier to identify true MVP and to
detect troublesome regurgitation. Based on these new rules, its now
believed that less than 3 percent of the population actually have true MVP, and
an even smaller percentage has serious complications from it.
Outlook
Most people who have MVP have no symptoms or medical
problems and dont need treatment. These people are 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 medicines to relieve their symptoms. Very few
people who have MVP need heart valve surgery to repair their mitral valve.
Rarely, MVP can cause complications, such as
arrhythmias (irregular heartbeats) or
infective endocarditis (EN-do-kar-DI-tis). Infective
endocarditis is a heart valve infection caused by bacteria that enter the
bloodstream and attach to the heart valves.
May 2008 |