echo conference april 6, 2011 frances canet, md. causes and anatomy assessment of mitral stenosis...

Echo Conference

April 6, 2011

Frances Canet, MD

• Causes and Anatomy

• Assessment of Mitral Stenosis

• How to Grade Mitral Stenosis

• Cases and Application

Outline

Rheumatic MSCommissural fusion

Degenerative MSAnnular calcificationAssociated with elderly, hypertension, atherosclerosis and aortic stenosis

Congenital MSAbnormalities of subvalvular apparatus

Other: Systemic lupus, infiltrative disease, carcinoid heart disease, drug-induced valve disease

Causes and Anatomy

Level 1 Recommendations:

Pressure gradient

MVA Planimetry

Pressure half-time

Level 2 Recommendations:

Continuity equation

Proximal isovelocity surface area method (PISA)

Stress echocardiography

How to Assess Mitral Stenosis

Continuous wave doppler is preferred

Gradient is measured in the apical window

Color doppler is used to identify eccentric diastolic mitral jets

Doppler beam is guided by the highest flow velocity zone identified by color doppler

Mean gradient is the relevant hemodynamic finding

Measure heart rate at which gradients are obtained

If patient is in atrial fibrillation, the mean gradient should be an average of five cycles with the least variation of R-R intervals

Pressure Gradient

Mitral Valve Area Planimetry

Direct tracing of the mitral orifice including opened commissures in the parasternal short-axis view at mid-diastoleAdvantages: -Direct measure of MVA-Does not involve hypothesis regarding flow conditions, cardiac chamber compliance or associated valvular lesions-Best correlation with anatomic valve area of explanted valves

Obtaining and measuring the image:

-Scan apex to the base of the LV to ensure the cross-sectional area is measured at the leaflet tips.

-Plane should be perpendicular to the mitral orifice, elliptical shape.

-Gain, sufficient to see contour of the mitral orifice.- If too excessive, may cause under estimation of the valve

area.

-Perform several measurements if the patient has atrial fibrillation or incomplete commissural fusion

Mitral Valve Area Planimetry

T1/2 = time interval in milliseconds between the maximum mitral gradient in early diastole and the time point where the gradient is half the maximum initial value

MVA = 220/ T1/2

Pressure half-time

Measuring T1/2 with a bimodal, non-linear decreasing slope of the E-wave

Based on assumption that the filling volume of diastolic mitral flow is equal to aortic SV.

MVA = pi (D2/4) (VTIAortic / VTIMitral)

D is the diameter of the LVOT in cm

VTI is in cm.

Accuracy and reproducibility is hampered by the number of measurements increasing the impact of errors of measurements.

Cannot be used in atrial fibrillation or associated significant MR or AR

Continuity equation – Level 2

MVA = pi (r2) (Valiasing) / Peak Vmitral x alpha/1800

R is the radius of the convergence hemisphere in cm

Valiasing is the aliasing velocity in cm/s

Peak Vmitral is the peak CWD velocity of mitral inflow in cm/s

alpha is the opening angle of mitral leaflets relative to flow direction

Proximal isovelocity surface area method – Level 2

Parasternal short-axis view

valve thickness (maximum and heterogeneity)

commissural fusion

extension and location of localized bright zones (fibrous nodules or calcification)

Parasternal long-axis view

valve thickness

extension of calcification

valve pliability

subvalvular apparatus (chordal thickening, fusion, or shortening)

Apical two-chamber view

subvalvular apparatus (chordal thickening, fusion, or shortening)

Detail each component and summarize in a score

Valve Anatomy

Enables measurement of mean mitral gradient and systolic pulmonary artery pressure during effort.

Semi-supine exercise echocardiography allows monitoring of gradient.

Useful in patients with equivocal or discordant with the severity of MS.

Stress Echocardiography – Level 2

How to Grade Mitral Stenosis

Normal MVA is 4.0-5.0 cm2 MVA >1.5 cm2 does not produce symptomsAs severity increases, cardiac output decreases and fails to increase during exercise.

Grades morphological changes in the MV during echo:

Leaflet mobility

Leaflet thickening

Valve calcification

Involvement of the subvalvular apparatus

Each characteristic is graded from 0-4, with a total of 16 points total.

A score >8 is predictive of low success post percutaneous mitral valvuloplasty.

Wilkins (Valvotomy )Score

72-year-old man with known moderate aortic stenosis, mitral regurgitation, hypertension, diabetes, COPD, TIA and severe pulmonary hypertension based on cardiac catheterization results is referred for echocardiogram to assess severity of mitral valve regurgitation.

How severe is his mitral regurgitation? Does he have mitral stenosis? What are his options for repair – calculate valvotomy score?

Case 1

PSL MV

PSL Zoom

PSL MV Color

4C AP

4C AP Color

MV Planimetry

PSS MV Planimetry Still

MV VTI for Pressure Gradient

MV half time 3

LVOT Diameter is 2.1

VTI aortic is 87

VTI mitral is 87.2

MVA = pi (D2/4) (VTIAortic / VTIMitral)

MVA = 3.89 cm2 (Not accurate compared to MVA of 1.15 cm2 calculated from pressure gradient. Remember, it is not accurate in patient with severe mitral regurgitation or atrial fibrillation.)

Less accurate calculation of MVA as it relies on several other measurements to be accurate.

Continuity equation

Valvotomy Score = 12Mobility – valve moves forward in diastole, moves mainly from base3 points

Subvalvular Thickening – thickening of chordal structures extending into 1/3rd of the chordal length 3 points

Thickening – extends through the entire leaflet3 points

Calcification – Brightness extending into the mid-portion of the leaflets3 points

Total score = 12

56-year-old woman with a history of rheumatic mitral valve stenosis, respiratory failure, heart failure, atrial fibrillation, recent stroke, COPD, sarcoidosis, schizophrenia was transferred from an outside hospital for a second opinion on mitral valve replacement. She has poor functional and neurologic status at present.

Evaluate the grade of her mitral stenosis and calculate her valvotomy score.

Case 2

PSL MV

PSL MV Zoom

PSL MV Color

4C AP MV

PSS Planimetry Loop

Planimetry Still

This is not acutally the area of the MV orfiice. Look at the small sliver of black area just below the tracing.

Pressure gradient

Pressure half-time

Resting mean pressure gradient: 16mmHg (severe is >10mmHg)

Mitral valve area using half time: 0.77cm2 (severe is <1.0 cm2 )

PHT: 285 ms (severe is greater than 220ms)

Grade of mitral stenosis: Severe

Valvotomy score:

Mobility: 4 – No or minimal forward movement of the leaflets.

Subvalvular Thickening: 2-3-

Thickening of chordal structures up to one-third of the chordal length possibly to distal third of the chords.

Thickening: 4 – Considerable thickening of all leaflet tissue (>8-10mm).

Calcification: 4 – Extensive brightness throughout much of the leaflet tissue.

Valvotomy score: 14 out of 16