Mitral regurgitation

Mitral regurgitation

1. Pathophysiology of Mitral Regurgitation Dr. Dharmraj Singh SR, Intensive Care CTVS

2. Mitral Valve apparatus Mitral leaflets Chodrae tendineae Papillary muscles Mitral annulus Abnormalities of any of these structures Causes MR

3. Major causes of MR Myxomatous degeneration (MVP & ruptured mitral chordae) Rheumatic heart disease Infective endocarditis HCM Annular calcification Dilated cardiomyopathy (DCM) Ischemic heart disease

4. Less common causes of MR Collagen vascular diseases Trauma Hypereosinophilic syndrome Carcinoid

5. Carpentier Functional Classification

6. Pathology In general, types II and IIIa usually are caused by primary disorders of the valve leaflets. Whereas types I and IIIb have relatively normal leaflets, which are distorted by LV and annular remodeling causing secondary MR. For clinical purposes , MR is classified as primary (or organic or degenerative) MR, caused by intrinsic disease of the mitral leaflets, and secondary (or functional) MR, caused by diseases of the left ventricle and/or mitral annulus.

7. Valve lesions in MR (A) Severe annular dilation leading to type I dysfunction. (B) Severe myxomatous changes with redundant, thick, and bulky segments in a patient with Barlow disease and type II dysfunction. (C) Rheumatic mitral valve disease with classic “fish mouth” appearance and type IIIA dysfunction. (D) Ischemic mitral valve disease caused by severe tethering of the P3 scallop leading to type IIIB dysfunction.

8. Abnormalities of Valve Leaflets Developed world - Myxomatous degeneration MV is a dynamic structure with protein turnover and remodelling continuing throughout life . MV is a thin (<3 mm) endothelium-lined bileaflet structure with- Fibrosa - dense collagen on the ventricular side Atrialis - less stiff layer of collagen and elastin on the atrial side Spongiosa - in b/w a loose connective tissue layer with abundant glycosaminoglycans Valvular interstitial cells (VICs) are Interspersed among the spongiosa- derived from endocardial endothelium, which normally are inactive .

9. Mechanisms of mitral valve prolapse Schematic showing the mechanism of myxomatous degeneration, with activation of valve interstitial cell to myofibroblasts that increase matrix production and turnover , secrete MMPs that drive collagen and elastin fragmentation, and release transforming growth factor (TGF)- β, which in turn promotes further cell proliferation and myofibroblast differentiation. GAGs, Glycosaminoglycans; MMP, matrix metalloproteinase. Mitral valve stained with hematoxylin and eosin to define the lesion of MVP as disruption of the fibrosa by myxoid extracellular matrix (*), which also infiltrates the collagen core of the chordae tendineae , one of which was ruptured ( arrow ). The elastin lamina beneath the atrialis is also disrupted.

10. Abnormalities of Valve Leaflets Myxomatous disease - depends on the relative degree of leaflet thickening and redundancy versus weakness in the chordae tendineae. On the extreme is Barlow syndrome , with gross leaflet thickening & redundancy, multiscalloped deep prolapse, and severe regurgitation arising from multiple points along the valve closure line. Developing world- chronic RHD remains a common cause of MR. In contrast with MS, rheumatic MR is more frequent in men than in women. It is a consequence of shortening, rigidity, deformity, and retraction of one or both mitral valve cusps and is associated with shortening and fusion of the chordae tendineae and papillary muscles .

11. Su rgical lesions in fibroelastic deficiency (A) Prolapse of P2 owing to multiple ruptured chordae; the leaflet tissue is thickened compared with other segments. Note the translucency of the anterior leaflet, and normal height and thickness of P1 and P3, in contrast to findings in Barlow’s disease. (B) Prolapse of P3 with ruptured chord. Note that P3 is thickened, but P2 and P1 are thin and of normal height. A B

12. Surgical lesions in Barlow’s disease. (A) Large valve with redundant, thick, bulky leaflets. (B) Tall, posterior leaflet with tip rising to anterior annulus. (C) Calcified anterior papillary muscle with fused, matted chords restricting the P1/P2 junction. (D) Atrialization of the base of the posterior leaflet. Note the blurring of the atrial-leaflet junction with fissures and microthrombi (arrows). A B C D

13. Abnormalities of the Mitral Annulus DILATION- Normal 93 +/- 9 mm (10 cm) Annular constriction contributes to valve closure. Dilation of LV and/or atrium, especially DCM & longstanding AF, Myxomatous disease CALCIFICATION- Idiopathic (degenerative) calcification Atherosclerosis, including systemic hypertension, hypercholesterolemia, and diabetes. Marfan and Hurler syndromes, chronic renal failure with secondary hyperparathyroidism, rheumatic involvement.

14. Abnormalities of the Chordae Tendineae Lengthening and rupture of the chordae tendineae are cardinal features of the MVP syndrome. Chordae may be congenitally abnormal Rupture - spontaneous (primary), infective endocarditis, trauma, rheumatic fever, or rarely, osteogenesis imperfecta or relapsing polychondritis . Secondary to trauma from percutaneous circulatory device

15. Involvement of the Papillary Muscles The posterior papillary muscle (PD branch of the RCA)- ischemic and infarcted more frequently Anterolateral papillary muscle (diagonal branches of the LAD & often by marginal branches from the LCX artery as well)

16. Surgical lesions in ischemic cardiomyopathy & IE (A) A dilated annulus with severe posterior leaflet tethering is characteristic of ischemic mitral regurgitation. (B) Perforation (arrow) of the anterior leaflet of the mitral valve secondary to infective endocarditis. A B

17. Left Ventricular Dysfunction Ischemic LV dysfunction and DCM LV dilation Obstructive HCM Hypereosinophilic syndrome endomyocardial fibrosis, trauma affecting the leaflets and papillary muscles, Kawasaki disease, LA myxoma, and various congenital anomalies, including cleft anterior leaflet and ostium secundum ASD

18. Chronic Primary MR Abnormal coaptation of mitral leaflets creates a regurgitant orifice during systole. Systolic pressure gradient b/w LA & LV is the driving force of regurgitant flow that results in a regurgitant volume . Regurgitant volume represent a percentage of total ejection of the LV and may be expressed as the regurgitant fraction . Regurgitant volume creates a volume overload by entering the LA in systole & the LV in diastole, modifying LV loading & function.

19. Pathophysiology In MR Impedance to ventricular emptying is reduced. Significant proportion of the regurgitant volume is ejected into the LA before the Aortic Valve opens and after it closes. volume of MR flow depends on a combination of the instantaneous size of the regurgitant orifice and the (reverse) pressure gradient between the LV & LA LV-LA gradient depends on SVR

20. LV in Chronic MR

21. Left Ventricular Compensation LV initially compensates for the development of acute MR by emptying more completely and by increasing preload (Frank-Starling principle). Acute MR reduces late systolic LV pressure and radius, LV wall tension declines markedly (and proportionately to a greater extent than LV pressure), permitting a reciprocal increase in the extent and velocity of myocardial fibre shortening and leading to a reduced end-systolic volume (ESV) When MR, particularly severe MR, becomes chronic, the LV end-diastolic volume (EDV) increases and the ESV returns to normal.

22. Left Ventricular Compensation ↑ LVEDV increases wall tension to normal or supra-normal levels in the “chronic compensated stage” of severe MR. ↑ LVEDV and mitral annular diameter may create a vicious circle in which MR leads to more MR. chronic MR, LVEDV and LV mass are increased; that is, typical volume overload (eccentric) hypertrophy develops degree of hypertrophy is often not proportional to the degree of LV dilation, so the ratio of LV mass/EDV may be less than normal, increasing wall stress.

23. Pathophysiology MR decreases impedence to LV – enhances LV emptying MR flow – instataneous Size of the orifice and LV-LA pressure gradient Torricelli principle – MRV = MROA x C x T x sq.root (LVP-LAP) LV-LA gradient – SVR MROA – Etiology of MR – variable response to drugs

24. STAGES OF MR

25. MR AND LV COMPENSATION MR begets more MR

26. LV in acute MR Increase in Pre-Load (Frank Starling principle) Decrease in After Load Increase in Ejection Fraction Increase in Total Stroke Volume Diminished Forward Stroke Volume

27. Acute severe Vs Chronic severe MR Acute Chronic Symptoms Almost always present, usually severe May be present Cardiac palpation Unremarkable Displaced dynamic apical impulse S 1 Soft Soft or normal Murmur Early systolic to holosystolic Holosystolic ECG Normal LVH and AF common CXR Normal cardiac silhouette; pulmonary edema Enlarged heart, normal lung fields ECHO Normal LA and LV Enlarged LA and LV

28. Ejection Indices in MR Ejection Fraction Indices Ejection Fraction (EF) Fractional Fibre Shortening (FS) Velocity of circumferential fibre shortening (VCF ) Inversely related to After load

29. Ejection Indices in MR Elevated in early MR Chronic MR – diastolic overload – myocardial dysfunction Indices modestly affected Low to normal indices – impaired myocardial function LVEF - 40-45% (moderate dysfunction) - severe LV dysfunction

30. End Systolic Volume/Dimensions Independent of pre-load Varies linearly with afterload Reduced – Acute MR Normal – Compensated Chronic MR Increased – Decompensated Chronic MR Pre-op value >40mm – impaired lv function post op Index for evaluating LV function Predictor of function and survival following MV surgery

31. End Systolic wall stress Better index of after load Accounts for ventricular geometry High end systolic wall volume for given end systolic wall stress – depressed contractility Predicts the prognosis for valve replacement

32. LA compliance Normal or Reduced Compliance In acute MR, marked increase in LA pressure LA thick walled Symptoms of pulmonary congestion

33. LA compliance Markedly Increased Compliance Thin walled, large LA Normal or slightly elevated LA pressure AF and low CO Moderately increased compliance Most common Variable sized LA/LA pressure -> AF

34. Symptoms of MR Mostly asymptomatic Chronic weakness & fatigue –most common Dyspnea/orthopnea/PND Palpitations Atypical chest pain Hemoptysis & systemic embolization- less common Acute MR -> Right sided heart failure Chronic MR -> Left sided heart failure

35. Physical examination Small volume brisk/jerky pulse – DEC FSV JVP a - Decreased RV compliance a, v - Right heart failure v - Severe TR/LAP In acute MR Hyperdynamic Apical impulse – LV Vol overload and dilatation Parasternal lift (dilated LA,RVH) Palpable S2 - severe PHTN

36. Physical Examination S1 , Loud S1 in MVP (Ejection click) S2 –Wide split, loud P2, S3+ Holosystolic murmur Severity inflicted by murmur intensity Radiates to axiila /back/base

37. Clinical presentation of chronic MR MVP Organic MR Functional MR Symptoms Chest pain Fatigue CHF Physical examination Mid-systolic click, End-systolic murmur Loud holosystolic murmur, S3 Soft early systolic murmur S4, S3 ECG ST-T changes Atrial fibrillation Q wave, LBBB CXR Pectus excavatum Cardiomegaly, LA enlargement Cardiomegaly, pulmonary edema

38. Roentgenographic findings Cardiomegaly with LA and left atrial appendages dilatation Giant left atria Annular calcification Interstitial edema with Kerley B lines

39. Echocardiography Mitral valve prolapse. A, Parasternal long-axis view showing deep prolapse of the posterior mitral leaflet. B, Anteriorly directed mitral regurgitation. AML, anterior mitral leaflet; PML, posterior mitral leaflet.

40. Grading of MR Severity Mild Moderate Severe Specific Signs of Severity Small central jet < 4 cm2 or < 20% of LA area* Vena contracta width < 0.3 cm No or minimal flow convergence† Signs of MR > mild present, but no criteria for severe MR Vena contracta width ≥ 0.7 cm with large central MR jet (area > 40% of LA) or with a wall-impinging jet of any size, swirling in LA* Large flow convergence† Systolic reversal in pulmonary veins Prominent flail MV leaflet or ruptured papillary muscle Supportive Signs of Severity Systolic dominant flow in pulmonary veins A-wave dominant mitral inflow‡ Soft density, parabolic CW Doppler MR signal Normal LV size§ Intermediate signs and findings Dense, triangular CW Doppler MR jet E-wave dominant mitral inflow (E > 1.2 m/sec)‡ Enlarged LV and LA size‖ (particularly when LV function is normal) Quantitative Parameters R Vol (mL/beat) RF (%) EROA (cm2) < 30 < 30 < 0.20 30-44 45-59 30-39 40-49 0.20-0.29 0.30-0.39 ≥ 60 ≥ 50 ≥ 0.40

41. Mild central MR Severe central MR Severe eccentric MR

42. Functional mitral regurgitation. A, Apical long-axis view showing a large posterior myocardial infarction, which is tethering the posterior leaflet preventing the anterior leaflet from closing. B, This causes a posteriorly directed jet of mitral regurgitation. AML, anterior mitral leaflet; PML, posterior mitral leaflet; arrow indicates tenting of the AML caused by tethering of the secondary chordae.

43. Severe mitral regurgitation caused by prolapse of the mitral valve with quantitative determination of effective regurgitant orifice area (ERO) on echocardiography. A, B, Severe prolapse of the mitral valve with severe MR. C, D, ERO was calculated with the proximal isovelocity surface area (PISA) radius and peak velocity of the MR jet.

44. Thank You