Mitral valve prolapse.

Mitral valve prolapse, diagnosed by auscultation of typical midsystolic clicks and late systolic murmurs or by echocardiographic demonstration of definite systolic protrusion of the mitral leaflets into the left atrium, is the commonest human abnormality of heart valves, affecting roughly 4 per cent of the population. The most important clinical features of mitral valve prolapse include palpitations and small but definite risks of infective endocarditis or significant mitral regurgitation in middle age, or later. Current evidence suggests that mitral prolapse is due to an inherited abnormality in connective tissue, which causes thoracic bony abnormalities and reduced body weight and blood pressure, in addition to the changes in the mitral valve.