Myxomatous mitral valve

Mitral valve prolapse (MVP) is a valvular heart disease characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. It is the primary form of myxomatous degeneration of the valve. There are various types of MVP, broadly classified as classic and nonclassic. In severe cases of classic MVP, complications include mitral regurgitation, infective endocarditis, congestive heart failure, and, in rare circumstances, cardiac arrest. Mitral valve prolapse (MVP) is a valvular heart disease characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. It is the primary form of myxomatous degeneration of the valve. There are various types of MVP, broadly classified as classic and nonclassic. In severe cases of classic MVP, complications include mitral regurgitation, infective endocarditis, congestive heart failure, and, in rare circumstances, cardiac arrest. The diagnosis of MVP depends upon echocardiography, which uses ultrasound to visualize the mitral valve. MVP is estimated to affect 2–3% of the population. The condition was first described by John Brereton Barlow in 1966. It was subsequently termed mitral valve prolapse by J. Michael Criley. Upon auscultation of an individual with mitral valve prolapse, a mid-systolic click, followed by a late systolic murmur heard best at the apex, is common. The length of the murmur signifies the time period over which blood is leaking back into the left atrium, known as regurgitation. A murmur that lasts throughout the whole of systole is known as a holo-systolic murmur. A murmur that is mid to late systolic, although typically associated with less regurgitation, can still be associated with significant hemodynamic consequences. In contrast to most other heart murmurs, the murmur of mitral valve prolapse is accentuated by standing and valsalva maneuver (earlier systolic click and longer murmur) and diminished with squatting (later systolic click and shorter murmur). The only other heart murmur that follows this pattern is the murmur of hypertrophic cardiomyopathy. A MVP murmur can be distinguished from a hypertrophic cardiomyopathy murmur by the presence of a mid-systolic click which is virtually diagnostic of MVP. The handgrip maneuver diminishes the murmur of an MVP and the murmur of hypertrophic cardiomyopathy. The handgrip maneuver also diminishes the duration of the murmur and delays the timing of the mid-systolic click. Both valsalva maneuver and standing decrease venous return to the heart thereby decreasing left ventricular diastolic filling (preload) and causing more laxity on the chordae tendineae. This allows the mitral valve to prolapse earlier in systole, leading to an earlier systolic click (i.e. closer to S1), and a longer murmur. Historically, the term mitral valve prolapse syndrome has been applied to MVP associated with palpitations, atypical precordial pain, dyspnea on exertion, low body mass index, and electrocardiogram abnormalities (ventricular tachycardia), syncope, low blood pressure, headaches, lightheadedness, and other signs suggestive of autonomic nervous system dysfunction (dysautonomia). Mitral valve prolapse is frequently associated with mild mitral regurgitation, where blood aberrantly flows from the left ventricle into the left atrium during systole. In the United States, MVP is the most common cause of severe, non-ischemic mitral regurgitation. This is occasionally due to rupture of the chordae tendineae that support the mitral valve. MVP may occur with greater frequency in individuals with Ehlers-Danlos syndrome, Marfan syndrome or polycystic kidney disease. Other risk factors include Graves disease and chest wall deformities such as pectus excavatum. For unknown reasons, MVP patients tend to have a low body mass index (BMI) and are typically leaner than individuals without MVP.