二尖瓣的病理生理学教学课件

1、Pathophysiology of Mitral Valve diseaseAlan SihoeCardiothoracic Surgery Teaching Round2nd August 20022021/01/211Pathophysiology of Mitral ValEpidemiology1998 in the UK:6471 first time valve replacementsof which 28% MVRNumbers increasing2021/01/212Epidemiology1998 in the UK:202Mitral Annulus: fibro-m

2、uscular skeletonAnchors base of valve leafletsLeaflets: conn tissue + muscle + vessels/nervesAnterior (aortic): larger; 1/3 of annulusPosterior (mural): 2/3 of annulusAnatomy2021/01/213Mitral Annulus: fibro-muscularAnatomyPapillary muscles:AnterolateralPosteromedialChordae tendinae1st, 2nd, 3rd orde

3、rApprox 25 major chordal trunks100 attachments to leafletsNo consensus on timing of muscle activity with cardiac cycle2021/01/214AnatomyPapillary muscles:2021/Annular dynamicsAnnular size Increases in late systole (maximum in diastole)Contracts in pre-systole (minimum in midsystole)Annular shapeMore

4、 eccentric in systoleAnnular positionMoves up towards LA in diastoleMoves down towards LV apex in systole2021/01/215Annular dynamicsAnnular size 2Leaflet dynamicsOpeningStarts in center, moving to edgesFlapping of edges at max. opening Closing(begins in late diastole)Bulging at base/annular attachme

5、ntLeaflet ascends towards LABulging rolls from annulus to edge2021/01/216Leaflet dynamicsOpening2021/01Mitral Stenosis (MS)Aetiology:RheumaticMale:female ratio is 1:2-3Acquired early (30mmHg: pulm transudation reduced lung compliancePulm art systolic pressure 60mmHg impedes RV emptying right heart f

6、ailureUltimately irreversible pulm vascular changes2021/01/2111MS: Pulmonary changesIn severeMS: Natural historyProgressive life-long diseaseLong latencySymptoms: Low cardiac output: dyspnoea, fatiguePulmonary congestion/HT (orthopnea, PND) right heart failure hemoptysisAtrial fibrillation / Thrombo

7、embolismCardiac cachexia2021/01/2112MS: Natural historyProgressiveMS: Natural historyOnset of symptoms to disability: 10 years10 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%Infectio

8、n 1-5%2021/01/2113MS: Natural historyOnset of syMS: InvestigationsCXR: LA enlargement, pulm congestionECG: LA enlargement (notched P in II, V1)atrial arrhythmias ?RVHEcho: valve area, LA/LV dimensionsDoppler: measures pressure gradientsTOE: better mitral/LA visualizationCardiac catheter: not essenti

9、alAssocd disease; LV ventriculography & pressures2021/01/2114MS: InvestigationsCXR: LA enlaMS: Medical therapyPharmacological Tx of mild heart failure, bronchitis, arrhythmias, hemoptysisEndocarditis prophylaxisAnticoagulation: Hx of AF/thromboembolismBalloon (or open) Valvuloplasty2021/01/2115MS: M

10、edical therapyPharmacologMS: Indications for surgerySymptomatic (NYHA class III-IV): MVR h long-term survival10 year survival: 0-20% 90% (89% at 15 yrs) h functional capacityValve area 1-1.5cm2 (normal 4-6 cm2)Systemic emboli2021/01/2116MS: Indications for surgerySymMS: Indications for surgeryClass

11、I-II: controversialRisk of SCD if asymptomatic: negligibleSurvival not improved by MVR?role of valvotomy (pulmonary HT, AF)MVR indicated when:Valve area NYHA class II+2021/01/2117MS: Indications for surgeryClaMitral Regurgitation (MR)Aetiology more diverse than MSMyxomatous degenerationLeading cause

12、 in West (30-70%)Defective fibroelastic tissue floppy valveMost asymptomaticComplicated by annular dilatation, chordal rupture, endocarditisRheumatic disease next most common2021/01/2118Mitral Regurgitation (MR)AetioMR: Carpentier classificationNormal leaflet motionAnnular / ventricular dilatationLe

13、aflet disease/perforation2021/01/2119MR: Carpentier classificationNMR: Carpentier classificationExcessive leaflet motion (prolapse)Chordal / papillary muscle elongation or rupture2021/01/2120MR: Carpentier classificationEMR: Carpentier classificationRestricted leaflet / chordal motione.g. fibrosis,

14、calcification, retraction 2021/01/2121MR: Carpentier classificationRMR: AetiologyMitral AnnulusMyxomatous degenerationSenile calcificationFunctional dilatation (e.g. myocarditis)Ring abscessMarfans2021/01/2122MR: AetiologyMitral Annulus202MR: AetiologyMitral leafletsRheumatic disease, endocarditis(1

15、-30%)Unknown why some develop MS, others MRFibrocalcific leaflet thickening (without fusion)Chordae shortened, annulus dilatedalso: congenital, connective tissue disease2021/01/2123MR: AetiologyMitral leaflets20MR: AetiologyChordaeIschaemiaMyxomatousInfectiveConnective tissueTraumaIdiopathic2021/01/

16、2124MR: AetiologyChordae2021/01/21MR: AetiologyPapillary muscle (10-25%)Dysfunction/ruptureIHD / MI: muscle & annular injuryfrank rupture rare, usually fatalesp. Posteromedial muscleAlso: abscess, sarcoid/amyloid, myocarditisMalalignmente.g. LV aneurysm, dilatation, myopathy2021/01/2125MR: Aetiology

17、Papillary muscle MR: HemodynamicsAcute:J LA pressure, pulm oedemaChronic: LA/PV compliance: i pulm congestnRegurgitant volume depends on:Mitral orifice sizeLV-LA pressure gradientHeart rateMedical Tx aims to control above factorsesp. decrease afterload to reduce LV dilatation2021/01/2126MR: Hemodyna

18、micsAcute:J LA prMR: Cardiac adaptationsLV: h preload, i afterloadLV dilated, more spherical, thinnedIncreased SV (O2 consumption not markedly h)But decompensation can gradually occurLA: h sizein chronic MR h complianceLess thromboembloism, AF than MS2021/01/2127MR: Cardiac adaptationsLV: h pMR: Sym

19、ptomsAcute: pulmonary congestion & oedemaChronic: may be prolonged asymptomatic phaseRisk of endocarditis Congestive heart failure & fatigue Right heart failure2021/01/2128MR: SymptomsAcute: pulmonary cMR: InvestigationsCXR: LA/LV enlargementECG: normal; LVH, ?AF/arrhythmiasEcho: leaflet morphology

20、& functionChamber dimensions, LV functionDoppler colour mappingCardiac catheter: assess coronaries, LVMRI: Dx, LV volumes, regurgitant fraction2021/01/2129MR: InvestigationsCXR: LA/LV eMR: Medical therapyMainstay: Afterload reduction i regurgitant volume i pulm congestion i LV volume i mitral orifice but: ongoing LV volume overload10% class I-II progress to III-IV per yearClass II-III survival on medical Mx