cardiovascular disorders
Mitral Valve Prolapse (MVP)
Etiology of Mitral Valve Prolapse
Mitral valve prolapse is most often caused by Myxomatous degeneration of the mitral valve leaflets and chordae tendineae In myxomatous degeneration, the fibrous collagen layer of the valve thins and mucoid (myxomatous) material accumulates. The chordae become longer and thinner and the valve leaflets enlarge and become rubbery. These changes result in floppy valve leaflets that can balloon back (prolapse) into the left atrium when the left ventricle contracts. Rupture of a degenerate chorda can allow part of the valve leaflet to flail into the atrium, which typically causes severe regurgitation. Degeneration is usually idiopathic, although it may be inherited in an autosomal dominant or, rarely, in an X-linked recessive fashion. Myxomatous degeneration may also be caused by connective tissue disorders (eg, Marfan Syndrome , Myxomatous degeneration less commonly affects the aortic or tricuspid valve, resulting in aortic or tricuspid prolapse. (MAD) is partial detachment of the mitral annulus from the ventricular myocardium, allowing for hypermobility of the mitral valve. MAD is strongly associated with mitral valve prolapse and Ventricular Fibrillation (VF) . Identification of MAD can alter the surgical technique used for mitral valve repair. Mitral Regurgitation (MR) due to mitral valve prolapse may occur in patients with apparently normal mitral valve leaflets (ie, nonmyxomatous) due to ischemic papillary muscle dysfunction or rheumatic chordal rupture. Transient MVP may occur when intravascular volume decreases significantly, as occurs in severe dehydration or sometimes during pregnancy (when the woman is recumbent and the gravid uterus compresses the inferior vena cava, reducing venous return). Mitral Regurgitation is the most common complication of mitral valve prolapse. MR may be acute (due to ruptured chordae tendineae causing flail mitral valve leaflets) or chronic. Sequelae of MVP with MR include Heart Failure (HF) , Ventricular ectopy commonly occurs in mitral valve prolapse. Severe ventricular arrhythmias or high ectopic burden occurs in<10% of cases and is associated with sudden cardiac death. 