Causes of Primary and Functional Mitral Regurgitation (MR) Causes of primary mitral regurgitation - Rheumatic heart disease: Most common cause in developing countries. Thickened and distorted MV. Often associated mitral stenosis - Infective/marantic endocarditis/tumors: Most common cause in developed countries. Destruction of MV tissue. Vegetations seen as thickening or mobile masses involving MV - Myxomatous degeneration/MV prolapse (Marfan syndrome, Ehler-Danlos syndrome, Barlow's disease, fibroelastic disease): Leaflets are thickened/redundant and prolapse beyond the annular plane into left atrium. MV chordae may rupture. - Mitral annular calcification: Age-related changes, chronic kidney disease Calcification may involve MV base and body, tip usually free. MR occurs because of MV leaflet malcoaptation and annulus dysfunction. - MV or LV papillary muscle injury: Direct/indirect chest wall trauma, LV infarction especially inferior wall - Congenital: MV clefts, parachute mitral valve - Secondary to systemic disease: Collagen vascular disease, carcinoid syndrome, hypereosinophilic syndrome. Thickened MV. - Drug induced: Anorectic drugs, dopamine agonists, ergot derivatives. Thickened MV. Causes of functional mitral regurgitation - Ischemic MR: MV leaflet tethering and displacement of coaptation point into LV produced by LV remodeling and dilatation with displacement of papillary muscles apically and laterally from myocardial infarction. Results in reduced/malcoaptation of MV with often asymmetric MR. MV annulus may be flattened. 'Sea gull' appearance of MV may result from a kink in the mid-portion of anterior leaflet produced by a stretched strut chord. - Nonischemic MR: Dilated CMP, long-standing HT, restrictive CMP, hypertrophic CMP (MR commonly pansystolic but may be nonpansystolic if it results from SAM). Mechanism same as above but MR often symmetric as LV dilatation symmetric. AF results in MR from dilated LA and MV annulus. RV pacing (especially apical) creates LV dyssynchrony which may lead to MR. #Mitral #Regurgitation #Causes #Primary #Functional #Differential #Diagnosis #Cardiology
