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Mitral Valve Prolapse

The mitral valve allows blood to flow from the left atrium to the left ventricle in the heart. Mitral valve prolapse (MVP) is the bulging (prolapse) of one or both of the mitral valve flaps (leaflets) into the left atrium when the heart contracts. When the flaps don’t close properly, blood leaks backward. This is called regurgitation. Regurgitation may cause a heart murmur, an abnormal sound in the heart caused by turbulent blood flow. When regurgitation is present, it’s generally mild. But it can get worse over time.

The mitral valve is located between the left atrium and the left ventricle and has 2 flaps. Normally the flaps are tightly closed by small tendon or “cords” that connect the flaps to the muscles of the heart. This closure prevents blood from flowing backwards. In MVP, the flaps enlarge and stretch inward toward the left atrium, sometimes “snapping” during heart contraction. This may allow some back-flow or regurgitation of blood into the left atrium.

MVP usually does not need to be treated because it is rarely a serious condition, and it doesn’t damage the heart. However, regular checkups with a doctor are advised.

What causes MVP?

The cause of MVP is unknown, but most cases are thought to be inherited. There are 2 forms of MVP: primary and secondary.

Primary MVP
Primary MVP means the mitral valve is abnormal because of one or more of these changes:

  • One or both of the flaps are too large and thick
  • The flap surfaces are scarred
  • The tendon cords are thinner or longer than they should be
  • There are fibrin deposits on the flaps

Primary MVP is most often an isolated disease. But is can be linked to other valve or skeletal problems. Some rare instances of MVP are hereditary.

Secondary MVP
In secondary MVP, another disease is linked to MVP. Often the valve flaps are not thickened. Prolapse occurs for other reasons. The prolapse may be from:

  • Damage caused by decreased blood flow from coronary artery disease to the muscles attached to the tendon cords
  • Functional changes in the heart muscle
  • Damage to valve structures caused by heart attack, rheumatic heart disease, valve infection, or hypertrophic cardiomyopathy. Hypertrophic cardiomyopathy is when the left ventricle of the heart is larger than normal.
  • Damage caused by a connective tissue disorder such as Marfan syndrome

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