Mitral_Valve_Pathophysiology-3(二尖瓣病理生理3).ppt

MS: Indications for surgery Class I-II: controversial Risk of SCD if asymptomatic: negligible Survival not improved by MVR ?role of valvotomy (pulmonary HT, AF) MVR indicated when: Valve area 1.5cm2 Pulmonary HT (higher risk) Thromboembolism ?Pregnancy planned Symptom progression NYHA class II+ Mitral Regurgitation (MR) Aetiology more diverse than MS Myxomatous degeneration Leading cause in West (30-70%) Defective fibroelastic tissue ? floppy valve Most asymptomatic Complicated by annular dilatation, chordal rupture, endocarditis Rheumatic disease next most common MR: Carpentier classification MR: Carpentier classification MR: Carpentier classification MR: Aetiology Mitral Annulus Myxomatous degeneration Senile calcification Functional dilatation (e.g. myocarditis) Ring abscess Marfan’s MR: Aetiology Mitral leaflets Rheumatic disease, endocarditis (1-30%) Unknown why some develop MS, others MR Fibrocalcific leaflet thickening (without fusion) Chordae shortened, annulus dilated also: congenital, connective tissue disease MR: Aetiology Chordae Ischaemia Myxomatous Infective Connective tissue Trauma Idiopathic MR: Aetiology Papillary muscle (10-25%) Dysfunction/rupture IHD / MI: muscle annular injury frank rupture rare, usually fatal esp. Posteromedial muscle Also: abscess, sarcoid/amyloid, myocarditis Malalignment e.g. LV aneurysm, dilatation, myopathy MR: Hemodynamics Acute: J LA pressure, pulm oedema Chronic: LA/PV compliance: i pulm congestn Regurgitant volume depends on: Mitral orifice size LV-LA pressure gradient Heart rate Medical Tx aims to control above factors esp. decrease afterload to reduce LV dilatation MR: Cardiac adaptations LV: h preload, i afterload LV dilated, more spherical, thinned Increased SV (O2 consumption not markedly h) But decompensation can gradually occur LA: h size in chronic MR h compliance Less thromboembloism, AF than MS MR: Symptoms Acute: pulmonary congestion oedema Chronic: may be prolonged asymptomatic phase Risk of endoca