The mitral valve is the valve between the left atrium and left ventricle. Normally, the mitral valve closes when the left ventricle starts to contract so blood cannot flow backward into the left atrium (regurgitation). In mitral valve prolapse, one or both valve flaps (called leaflets) are enlarged, and some of their supporting "strings" known as chordae (“kor–day”) may be too long. When the left ventricle contracts, part of one or both leaflets fall backward (prolapse) into the left atrium. This sometimes causes a small amount of blood to leak backward through the valve into the left atrium which is called mitral valve regurgitation.
Due to the abnormal flow of blood, an abnormal heart murmur may be heard. In children, mitral valve prolapse is uncommon. When it is seen in children, it may be associated with other abnormalities or syndromes such as Marfan syndrome, storage diseases or other types of disease. Like many diseases, mitral valve prolapse has a spectrum from a nearly normal valve with very mild prolapse and little or no leakiness to a very enlarged or redundant valve with significant leakiness (regurgitation).
The majority of patients with mitral valve prolapse do not have any symptoms at all and do not require any treatment or restriction in activity. There may be symptoms of chest pain or heart racing (palpitations), but most of the time, these symptoms have nothing to do with and are unrelated to the mitral valve prolapse.
The usual method of diagnosis is by listening to the heart with a stethoscope and hearing the abnormal murmur made by mitral valve prolapse. This murmur is usually quite characteristic. However, there are some other heart defects that sound similar. The diagnosis can be confirmed most of the time using echocardiography. However, caution must be used in diagnosing mitral valve prolapse using echocardiography since many normal people have slight bulging of the mitral valve back into the left atrium. Because of this, mitral valve prolapse may be overdiagnosed and unnecessary treatment and/or restrictions may result.
Treatment depends on the severity of the prolapse. Very mild prolapse with no leakiness requires no treatment or restrictions. Mitral valve prolapse with moderate or severe regurgitation may require medication or surgery to prevent complications and improved lifestyle. Medications such as ACE inhibitors may be used to lower blood pressure and help prevent the leakiness to become worse. Other medications may be used to help heart function or decrease the size of the heart. To prevent the valve from becoming infected, those who have leaky (regurgitant) prolapsing valves will need antibiotics before certain surgical or dental procedures likely to cause bleeding.
In general, the outlook for children with mitral valve prolapse is very good. However, this depends on the severity of the prolapse and regurgitation. Patients with more severe regurgitation and very redundant valves are at a greater risk for decreased heart function, rhythm abnormalities and strokes (from clots forming on the valve). For these patients, there is always a risk of endocarditis; therefore preventive measures against bacterial endocarditis are indicated for life. Valve repair or replacement may be required in these severe cases. Most of the time, mitral valve prolapse is very mild and requires only check-ups to make sure it is still mild. For these cases, no restrictions are required, and preventive measures for bacterial endocarditis may not be required. Your pediatric cardiologist can tell you the severity, the frequency of follow-up and whether restrictions or prophylaxis are needed.