2 Outline: Mitral Stenosis I. Normal Mitral Valve AnatomyII. Etiology and EpidemiologyIII. Echocardiography EvaluationIV. Physiologic DisturbancesV. Treatment Options
3 FIGURE 62–27 Continuity of the mitral apparatus and the left ventricular myocardium. Mitral regurgitation (MR) may be caused by any condition that affects the leaflets or the structure and function of the left ventricle. Similarly, a surgical procedure that disrupts the mitral apparatus in an attempt to correct MR has adverse effects on left ventricular geometry, volume, and function. (From Otto CM: Evaluation and management of chronic mitral regurgitation. N Engl J Med 345:740, 2001.)
4 Mitral Valve Anatomy Posterior leaflet encircles majority of annulus Anterior leaflet is longer across diameter of valve
9 FIGURE 62–18 Rheumatic mitral stenosis FIGURE 62–18 Rheumatic mitral stenosis. There are severe valvular changes, including marked fibrosis and calcification of the mitral valve leaflets and severe chordal thickening and fusion into pillars of fibrous tissue. (From Becker AE, Anderson RH [eds]: Cardiac Pathology: An Integrated Text and Colour Atlas. New York, Raven Press, 1983, p 4.3.)
10 Epidemiology: Rheumatic Mitral Stenosis Leading cause of congestive heart failure in developing countriesWithout surgical intervention, mitral stenosis results in 85% mortality 20 years after onset of symptoms2/3 of all cases are in womenAge of onset of symptoms usually age 20 – 4050% of patients with symptomatic MS have history of acute rheumatic fever 20 yrs prior
11 Time from episode of RF to symptoms range from 2 – 30 years, most frequently occuring around 15 – 20 years from illness
12 Echocardiographic Evaluation A) Valve anatomy, mobility, calcificationB) Assessment of severity:1)Mitral valve area- continuity equation method and PISA- planimetry- pressure half time method2)Transmitral pressure gradient (Bernoulli)3)Sequelae (pulmonary hypertension, left atrial dilation, left atrial thrombus)
18 Calcific Mitral Stenosis Mitral Annular Calcification occurs at annulus adjacent to posterior leafletCalcification extends from annulus to base of leafletLeaflet tips remain thin and flexible
19 Use of 3D Echocardiography Can be transthoracic or transesophagealImproves determination of involvement of chordal structuresFurther characterizes fibrosis and calcification of leaflets
20 3D EchocardiographyFIGURE 14–5C A, 3D pyramidal image of apical four-chamber view. Shaded area, Midportion of the pyramid. B, Cropping the top half of the pyramid shows the four chambers clearly, with much better definition of the spatial relationships of various cardiac structures. C, Still frame of real-time 3D imaging of apical four-chamber view from patient with mitral stenosis. The thickened and restricted motion of the mitral valve (arrows) is well shown. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. (From Oh JK, Seward JB, Tajik AJ: The Echo Manual, 3rd edition. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)
21 Fish Mouth AppearanceFIGURE 14–4C A, 3D pyramidal imaging along parasternal short-axis view. Shaded area, Midportion of the pyramid. B, Diagram of the view from the apex after half the pyramid was cropped away. C, 3D echocardiographic image along parasternal short-axis view from patient with mitral stenosis. Note fish-mouth appearance of mitral valve orifice (arrows). (From Oh JK, Seward JB, Tajik AJ: The Echo Manual. 3rd ed. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)
22 M-Mode Increased echogenicity of leaflets Decreased excursion and reduced separation of anterior and posterior leafletsReduced diastolic E-F slope of mitral closureParadoxical anterior diastolic motion of posterior mitral leaflet (due to tethering of posterior leaflet to anterior leaflet in rheumatic MS)
23 FIGURE 14–6C A, An M-mode cursor is placed along different levels (1, ventricular; 2, mitral valve; 3, aortic valve level) of the heart, with parasternal long-axis 2D echocardiographic guidance. B, EDd and ESd are end-diastolic and end-systolic dimensions, respectively, of the left ventricle (LV). C, M-mode echocardiogram of the anterior mitral leaflet: A, peak of late opening with atrial systole; C, closure of mitral valve; D, end-systole before mitral valve opening; E, peak of early opening; F, mid-diastolic closure. D, Double-headed arrow, dimension of the left atrium (LA) at end-systole. Ao = aorta; AV = aortic valve; PW = posterior wall; RV = right ventricle; RVOT = right ventricular outflow tract; VS = ventricular septum. (From Oh JK, Seward JB, Tajik AJ: The Echo Manual. 3rd ed. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)
25 E Point Septal Separation FIGURE 14–50A A, M-mode echocardiogram of a patient with mitral stenosis. Note the abnormal motion of the anterior mitral valve leaflet as demonstrated by the E-F slope (arrow). B, 2D echocardiogram of parasternal long-axis view during diastole of a patient with mitral stenosis. The mitral valve leaflets are thickened and have the typical “hockey-stick” appearance (arrow). Left atrium (LA) is enlarged. LV = left ventricle; RV = right ventricle; * = descending thoracic aorta.Reduced diastolic E – F slope of closure
26 Diastolic Anterior Motion of Posterior Leaflet Normal Mitral Stenosis
27 Assessment of Severity Transmitral Pressure Gradient1)Bernoulli’s equationMitral valve area1) Continuity equation2) PISA3) Planimetry4) Pressure half time
28 Continuity EquationCross sectional area of the mitral valve multiplied by velocity time integral of mitral stenosis jet=Cross sectional area of LVOT(or PA) multiplied by velocity time integral of LVOT (or PA)Therefore:CSA(mitral)= stroke volume/VTI(mitral)Wont work if there is significant MR – if there is MR you need to use the PISA method
29 Proximal Isovelocity Surface area: PISA Used for calculating continuity equation in setting of mitral regurgitationBlood flow increases as nears the stenotic orificeColor doppler flow parameters are adjusted to demonstrate well defined hemispherical aliasing surface are on the atrial side of the mitral orificeVelocity equals Nyquist limitCSA(mitral)=2 π r2 x velocityaliasing/velocitypk transmitral
30 FIGURE 14–44 Left, A young woman with dyspnea following mitral valve repair. Transesophageal imaging shows narrowed mitral annulus area with a small soft tissue mass. Continuous wave Doppler recording across the repaired mitral valve shows peak mitral flow velocity (arrow) of 2.5 m/sec (= 250 cm/sec). Right, Color flow imaging with a downward baseline shift (same direction as that of mitral stenosis jet) across a stenotic mitral valve. A nice hemispheric proximal isovelocity surface area (PISA) is seen in the left atrium (LA) because of mitral stenosis. PISA radius is 1 cm. Hence, stenotic mitral valve area (MVA) is calculated as follows:MVA = 6.28 X (1)2 X 4/250 = 1.02 cm2Because the surface of PISA is flat, no angle correction is necessary in this case. LV = left ventricle.
31 Planimetry2D short axis imaging of mitral valve during diastole allows direct planimetry of valve areaMitral valve is a planar elliptical orifice that is constant in mid diastolePlanimetry should be done at the narrowest cross sectional area at the leaflet tipsConsider starting at apex and slowly scanning up to find most distal point of leaflets (mitral valve shaped like a funnel during diastole)Accuracy of measurement has been validated by comparison to post surgical specimens
33 Pressure Half TimePrinciple: rate of pressure decline across stenotic orifice is determined by CSA of the orificeInfluence of LA & LV compliance assumed to be negligibleObtain doppler images of mitral inflowPressure half time = time from Vmax to Vmax/√2Mitral valve area = 220/ pressure half time
35 Transmitral Pressure Gradient Peak Diastolic Pressure gradient = 4(orifice velocity)2Mean Diastolic Pressure gradient =4 (v12 + v22 + v vn2)/ nWhere vx is an instantaneous velocityMitral valve area of 1 cm2 typically requires transmitral gradient of20 mmHg to maintain normal cardiac output at rest.However, severe mitral stenosis can present with a resting gradientranging from 5 – 30 mm Hg.
39 Patient Selection for Valvuloplasty 1)Severity of symptoms and physiologic changes- resting and stress echo2)Risk of procedural complications-resting echo
40 Wilkins Score: Assessment of Mitral Valve Morphology Patient selection for predicted hemodynamic results and risk of procedural complications.Suitability for BVM is determined by valve morphology and the amount of mitral regurgitation present. The Wilkins score gives a rough guide to the suitability of the mitral valve’s morphology for BMV. This scoring system assigns a point value from 1 to 4 for each of (1) valve calcification, (2) leaflet mobility, (3) leaflet thickening, and (4) disease of the subvalvular apparatus. In general, patients with a score of 9 and less than moderate mitral regurgitation have the best outcomes, although many patients have benefited from BMV despite higher valve scores.40
41 Selection for Valvuloplasty Score < 8: probably valvuloplasty unless:> 2+ mitral regurgitationprevious surgical commissurotomyScore 9-11: possible valvuloplasty if:No mitral regurgitationAge < 45Score 12-14: surgical commissurotomyMay consider as palliative procedurePalacios et al. Circulation. 2002
48 FIGURE 62–20 Schematic representation of left ventricular (LV), aortic, and left atrial (LA) pressures, showing normal relationships and alterations with mild and severe mitral stenosis (MS). Corresponding classic auscultatory signs of MS are shown at the bottom. Compared with mild MS, with severe MS the higher left atrial v wave causes earlier pressure crossover and earlier mitral valve (MV) opening, leading to a shorter time interval between aortic valve (AV) closure and the opening snap (OS). The higher left atrial end-diastolic pressure with severe MS also results in later closure of the mitral valve. With severe MS, the diastolic rumble becomes longer and there is accentuation of the pulmonic component (P2) of the second heart sound (S2) in relation to the aortic component (A2).
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