mitral valve prolapse

noun

: a valvular heart disorder in which one or both mitral valve flaps close incompletely during systole usually producing either a click or murmur and sometimes mitral regurgitation and which is often a benign symptomless condition but may be marked by varied symptoms (as chest pain, fatigue, dizziness, dyspnea, or palpitations) leading in some cases to endocarditis or ventricular tachycardia

—abbreviation MVP

called also Barlow's syndrome