Mitral regurgitation is common. When you hear this murmur and are trying to determine the underlying cause, think about the individual components of the mitral valve, and particular disease states which may affect them. Let's start at the annulus, and work our way down:
- Annulus: This may be dilated from cardiomyopathies, or calcified in diseases like rheumatic fever or chronic renal failure.
- Leaflets: The mitral leaflets can fail in a number of disease states, including infectious endocarditis (acute or chronic), rheumatic fever, autoimmune conditions (SLE, scleroderma), myxomatous degeneration (MVP), connective tissue diseases (eg. Marfans), and congenital malformations.
- Chordae: These can be damaged or rupture under ischemic, infected, or traumatic conditions and in rheumatic heart disease.
- Papillary Muscle: These muscles can rupture after trauma or infarct. They become 'dysfunctional' under ischemic conditions, or when the LV becomes dilated (myopathy or aneurysm). Papillary muscle can also become infected, and rarely can have infiltration with amyloid deposits or granuloma (eg. sarcoid).