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Degenerative mitral valve disease with emphasis on mitral valve prolapse

Degenerative mitral valve disease is responsible for the syndromes of billowing mitral leaflet, mitral valve prolapse (MVP), floppy mitral valve, and flail leaflet.1–6 The pathology of these is mainly caused by myxomatous infiltration and fibroelastic deficiency.

In the 1960s, Reid7 and Barlow and colleagues1 proposed that mid to late systolic clicks and apical late systolic murmurs were of mitral valvar origin. This origin was further documented by intracardiac phonocardiography.8 Criley and colleagues used “mitral valve prolapse” to describe posterior mitral leaflet motion in systole.9 Since then, MVP has remained a diagnosis of sustained interest and controversy.

Because MVP is asymptomatic or has a non-specific clinical presentation, the disease is often detected by the non-ejection systolic click of the mitral valve and the late systolic murmur. MVP is clinically benign with potential for serious complications in otherwise healthy people, such as degenerative mitral regurgitation and infective endocarditis. Age and sex distributions as well as the frequencies of chest pain, dyspnoea, and ECG abnormalities were not significantly different between subjects with and without MVP,10–12 demonstrating that the previously reported associations were probably caused by a selection bias. These recent studies also showed that patients with MVP had lower body mass index than those without MVP. Many disorders have been associated with MVP but we do not know whether these associations are a casual coincidence, a common link or an expression of a genetic disturbance.

Histologic patterns of degenerative mitral valve disease include myxomatous infiltration, fibroelastic deficiency, collagen alterations, and mucopolysaccharide accumulation.13 Elongated or ruptured chordae are often associated with these abnormalities. Because the distribution of mitral leaflet layers, namely auricularis, spongiosa, fibrosa, and ventricularis, is different in the basal, middle, and distal thirds of the leaflet, histologic abnormalities may vary accordingly. Myxomatous infiltration …