Mitral Regurgitation (MR)

Mitral Regurgitation (MR)

·        Causes:

o  Abnormalities of leaflets:

§  Rheumatic heart disease ® post inflammatory scarring

§  Infective endocarditis

§  Degenerative change

§  Floppy valve syndrome = mitral valve prolapse. Immaterial haemodynamic changes (Þ normal heart size, etc). Common - ?5-10% of young women. Mid/late systolic murmur +/-mid/late systolic click. Complications (3% of affected) are infective endocarditis, mitral regurgitation, and embolism of leaflet thrombi

§  Congenital

§  SLE can cause Libman-Sacks endocarditis: sterile immune mediated endocarditis mainly affecting underside of mitral valve (cf other vegetative endocarditis on top)

o   Abnormalities of tensor apparatus: Previous MI: e.g. fibrosis or rupture of papillary muscle

o   Abnormalities of LV cavity or valve ring:

§  Calcification of mitral ring (especially elderly women)

§  LV enlargement (whole ventricle expands). Dilatation of the mitral annulus and lateral displacement of the papillary muscles

§  Hypertrophic cardiomyopathy (thickening in parts of wall – e.g. enlarged septum disrupts flow to aortic valve). Anterior displacement of the anterior leaflet

o   Existing MR – begets MR.  Enlargement of LV pulls posterior leaflet away from the mitral orifice

·        Signs:

o   Pan-systolic murmur: regurgitation throughout the whole of systole. Loudest at apex. Radiates over precordium and into axilla. No S1. No opening snap unless concurrent stenosis. Early diastolic flow murmur

o   In severe MR, Aortic valve closes prematurely ® split S2

o   S3 caused by sudden tensing of papillary muscles, chordae tendinae and valve leaflets

o   Small volume pulse

·        Significant difference between acute and chronic presentations:

o   Pulmonary oedema and RV overload much more significant if acute. In chronic, enlargement of the LA reduces pulmonary „back flow‟

o   AF better tolerated than in mitral stenosis

o   RHF rare unless acute presentation or LVF

·        Leads to:

o   Eventually leads to LV and LA hypertrophy (may take decades)

o   AF common – mostly correlated with age

o   Infective endocarditis (in 20%)

o   Systemic embolisation

o   Pulmonary hypertension (but much later compared with mitral stenosis)

·        Differential:

o   Hypertrophic cardiomyopathy: both long systolic murmurs, but MR radiates to the axilla, hypertrophic cardiomyopathy radiates centrally

o   VSD