The mitral valve is located between the left atrium (upper heart chamber that receives oxygenated blood from the lungs) and the left ventricle (the heart’s main pumping chamber). Normally, blood flows one way from the left atrium to the left ventricle through the mitral valve which closes after each heart contraction. In mitral valve prolapse (also known as floppy valve), the valve opening (leaflets) is weak or thickened. When the heart beats, the valve can “flop” back like a balloon into the left atrium. This is called prolapse. In some cases, the valve doesn’t close properly and blood can leak back into the left atrium (mitral valve regurgitation).
Prolapse is a common condition in which the valve's connective tissue and anchoring chords gradually degenerate. The exact cause is unknown. Only cases causing regurgitation require treatment.