myxomatous degeneration
Summary
Myxomatous degeneration is a pathological process affecting heart valves where normal collagenous tissue is replaced by loose, gelatinous myxomatous tissue rich in glycosaminoglycans. This leads to valve thickening, redundancy, and prolapse, most commonly affecting the mitral valve in mitral valve prolapse (MVP).
Detail
Myxomatous degeneration represents a degenerative process where the normal organized collagen and elastin fibers in heart valve leaflets are replaced by loose, disorganized myxomatous tissue containing increased glycosaminoglycans (particularly chondroitin sulfate and dermatan sulfate). This results in valve leaflets becoming thickened, redundant, and floppy. The mitral valve is most commonly affected, leading to mitral valve prolapse, though aortic, tricuspid, and pulmonary valves can also be involved. The degeneration weakens valve structure, causing leaflets to balloon back into the atrium during systole. In severe cases, this can progress to mitral regurgitation due to incomplete valve closure or chordae tendineae rupture. The condition can be primary (idiopathic) or secondary to connective tissue disorders like Marfan syndrome, Ehlers-Danlos syndrome, or osteogenesis imperfecta. Histologically, the spongiosa layer of the valve shows marked expansion with myxomatous material, while the fibrosa and ventricularis layers become disrupted.
Sources
- Robbins and Cotran Pathologic Basis of Disease
- Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine
- First Aid for the USMLE Step 1
- Pathoma: Fundamentals of Pathology
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