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Genes, gender and geometry and the prolapsing mitral valve
Author(s) -
Wilcken David E. L.
Publication year - 1992
Publication title -
australian and new zealand journal of medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.596
H-Index - 70
eISSN - 1445-5994
pISSN - 0004-8291
DOI - 10.1111/j.1445-5994.1992.tb00476.x
Subject(s) - medicine , mitral valve prolapse , cardiology , mitral valve , population , marfan syndrome , autopsy , mitral regurgitation , environmental health
Abstract Mitral Valve Prolapse (MVP) is usually a variant of normal occurring in about 4% of the population. Complications are relatively uncommon, but false associations due to ascertainment bias have had a potential for iatrogenic harm. Adverse outcomes which do occur in a subset of MVP subjects are considered here in relation to the contributions of genes, gender and geometry. There are definite associations between MVP and several dominantly inherited connective tissue abnormalities; it occurs in 85% of adults with Marfan syndrome. All these contribute to a very small proportion of the MVP population. A larger less easily characterised group with dominant inheritance and some features of a connective tissue disorder awaits DNA studies for identification. For most MVP subjects our data define significant family aggregation consistent with polygenic inheritance; the likelihood of a first degree relative having MVP is about two and a half times the population average. There is a higher prevalence in young women than in men—5% versus 3%; this has also been demonstrated for floppy mitral valve (MV) at autopsy. MVP complications of chordal rupture, severe mitral regurgitation and infective endocarditis are, however, two to three times more common in men, are age related and evident after the age of 50 years. Higher blood pressure in men may contribute to this in accordance with a response‐to‐injury hypothesis to explain progressive valve changes. Leaflet, annulus and left ventricular size differences and septal changes are geometric variants with a potential for increasing tension‐related valve injury. Changes in excised floppy valves are consistent with ongoing repair in response to repetitive leaflet and chordal injury involving enhanced type III collagen gene expression and proteoglycan synthesis. This myxomatous change constitutes the final common pathway to serious mitral regurgitation and the rare occurrence of sudden death. The response‐to‐injury concept has implications for treatment to minimise progressive changes.