Mitral Regurgitation Primary Causes
Primary mitral regurgitation is due to any disease process that affects the mitral valve apparatus itself.
The causes of primary mitral regurgitation include:
- Myxomatous degeneration of the mitral valve
- Ischemic heart disease / Coronary artery disease
- Infective endocarditis
- Collagen vascular diseases (ie: SLE, Marfan's syndrome)
- Rheumatic heart disease
- Trauma
- Balloon valvulotomy of the mitral valve
- Certain forms of medication (e.g. fenfluramine)
The most common cause of primary mitral regurgitation in the United States (causing about 50% of primary mitral regurgitation) is myxomatous degeneration of the valve. Myxomatous degeneration of the mitral valve is more common in males, and is more common in advancing age. It is due to a genetic abnormality that results in a defect in the collagen that makes up the mitral valve. This causes a stretching out of the leaflets of the valve and the chordae tendineae. The elongation of the valve leaflets and the chordae tendineae prevent the valve leaflets from fully coapting when the valve is closed, causing the valve leaflets to prolapse into the left atrium, thereby causing mitral regurgitation.
Ischemic heart disease causes mitral regurgitation by the combination of ischemic dysfunction of the papillary muscles, and the dilatation of the left ventricle that is present in ischemic heart disease, with the subsequent displacement of the papillary muscles and the dilatation of the mitral valve annulus.