二尖瓣的病理生理学课件

PathophysiologyPathophysiology of of MitralMitral Valve disease Valve disease Alan Sihoe Cardiothoracic Surgery Teaching Round 2nd August 2002 Epidemiology 1998 in the UK: 6471 first time valve replacements of which 28% MVR Numbers increasing Mitral Annulus: fibro-muscular skeleton Anchors base of valve leaflets Leaflets: conn tissue + muscle + vessels/nerves Anterior (aortic): larger; 1/3 of annulus Posterior (mural): 2/3 of annulus Anatomy Anatomy Papillary muscles: Anterolateral Posteromedial Chordae tendinae 1st, 2nd, 3rd order Approx 25 major chordal trunks 100 attachments to leaflets No consensus on timing of muscle activity with cardiac cycle Annular dynamics Annular size Increases in late systole (maximum in diastole) Contracts in pre-systole (minimum in midsystole) Annular shape More eccentric in systole Annular position Moves up towards LA in diastole Moves down towards LV apex in systole Leaflet dynamics Opening Starts in center, moving to edges Flapping of edges at max. opening Closing(begins in late diastole) Bulging at base/annular attachment Leaflet ascends towards LA Bulging rolls from annulus to edge MitralMitral StenosisStenosis (MS) (MS) Aetiology:Rheumatic Male:female ratio is 1:2-3 Acquired early (30mmHg: pulm transudation reduced lung compliance Pulm art systolic pressure 60mmHg impedes RV emptying right heart failure Ultimately irreversible pulm vascular changes MS: Natural history Progressive life-long disease Long latency Symptoms: Low cardiac output: dyspnoea, fatigue Pulmonary congestion/HT (orthopnea, PND) right heart failure hemoptysis Atrial fibrillation / Thromboembolism Cardiac cachexia MS: Natural history Onset of symptoms to disability: 10 years 10 year survival: Asymptomatic (NYHA class I) 80% (progression) Symptomatic (NYHA class III) 20% Causes of death: CHF 60-70% Systemic embolism 20-30% Pulmonary embolism 10% Infection 1-5% MS: Investigations CXR: LA enlargement, pulm congestion ECG: LA enlargement (notched P in II, V1) atrial arrhythmias ?RVH Echo: valve area, LA/LV dimensions Doppler: measures pressure gradients TOE: better mitral/LA visualization Cardiac catheter: not essential Assocd disease; LV ventriculography LVH, ?AF/arrhythmias Echo: leaflet morphology & function Chamber dimensions, LV function Doppler colour mapping Cardiac catheter: assess coronaries, LV MRI: Dx, LV volumes, regurgitant fraction MR: Medical therapy Mainstay: Afterload reduction i regurgitant volume i pulm congestion i LV volume i mitral orifice but: ongoing LV volume overload 10% class I-II progress to III-IV per year Class II-III survival on medical Mx: 5 year: 50% 10 year: 25% MR: Natural history Variable aetiology difficult to predict Difficult to identify those progressing to irreversible LV damage Prognostic indicators: LV function Degree of regurgitation Underlying aetiology (esp. CAD) MR: Indications for surgery Acute: muscle/chordal rupture with shock Immediate MVR Chronic, NYHA class II-IV: MVR Aim for surgery before irreversible LV change LV dimension is a predictor of outcome MR: Indications for surgery Chronic, asymptomatic: surveillance Surgery if LV systolic dysfunction