Mitral valve prolapse (MVP) is a common condition in which the mitral valve between the left upper chamber (left atrium) and left lower chamber (left ventricle) of the heart does not function properly. In most people, mitral valve prolapse does not cause any symptoms, usually does not cause any health problems, and does not require treatment.
In mitral valve prolapse, the valve flaps bulge (prolapse) upward into the left atrium rather than closing smoothly as the heart contracts. In rare cases, blood may leak backward through the prolapsed valve into the atrium. This condition is called mitral valve regurgitation.