Mitral valve prolapse: myxomatous degeneration and what it leads to
- Lesion
In mitral valve prolapse, the valve leaflets become soft and floppy and bulge back into the atrium when the heart contracts.
What it is
In mitral valve prolapse, one or both mitral leaflets are enlarged, redundant and floppy and balloon back into the left atrium during systole. It affects about 2 to 3 % of adults. The basic change is myxomatous degeneration: the middle spongiosa layer thickens with proteoglycan and the fibrosa layer, which gives strength, thins. Most cases are isolated and probably genetic; some occur with Marfan syndrome and other connective tissue disorders. Most people have no symptoms, but some develop regurgitation, endocarditis, arrhythmias or chordal rupture.
Structure
- Gross: intercordal ballooning (hooding) of the posterior leaflet is most typical; leaflets thick and rubbery.
- Microscopy: proteoglycan-rich spongiosa intruding into the fibrosa; secondary fibrosis on the leaflet surfaces where they rub.
- Similar myxomatous change can affect the tricuspid, aortic or pulmonary valves.
Clinical notes
- Most people with prolapse have a normal life expectancy; severe regurgitation may need valve repair.
Test yourself
Think of the answer, then tap the question to see it.
What is the key histological change in mitral valve prolapse?
Myxomatous degeneration: thickening of the spongiosa with proteoglycan and thinning of the collagen-rich fibrosa.
Which auscultatory finding is classic?
A mid-systolic click, often followed by a late systolic regurgitant murmur.
Which genetic syndrome is commonly associated with mitral valve prolapse?
Marfan syndrome (fibrillin-1 mutation).
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Mitral valve prolapse: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Mitral Regurgitation (StatPearls (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.