Echo Conference
April 6, 2011
Frances Canet, MD
Outline
•
Causes and
Anatomy
•
Assessment of
Mitral Stenosis
•
How to Grade
Mitral Stenosis
•
Cases and
Application
Causes and Anatomy
Rheumatic MS
Commissural fusion
Degenerative MS
Annular calcification
Associated with elderly, hypertension,
atherosclerosis and aortic stenosis
Congenital MS
Abnormalities of subvalvular apparatus
Other: Systemic lupus, infiltrative disease, carcinoid
heart disease, drug-induced valve disease
How to Assess Mitral Stenosis
Level 1 Recommendations:
Pressure gradient
MVA Planimetry
Pressure half-time
Level 2 Recommendations:
Continuity equation
Proximal isovelocity surface area method (PISA)
Stress echocardiography
Pressure Gradient
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
Mitral Valve Area Planimetry
Direct tracing of the mitral orifice including opened commissures in the
parasternal short-axis view at mid-diastole
Advantages:
- 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
Mitral Valve Area Planimetry
Obtaining and measuring the image:
-Scan apex to the base of the LV to ensure the crosssectional 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
Pressure half-time
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
Measuring T1/2 with a bimodal, nonlinear decreasing slope of the E-wave
Continuity equation – Level 2
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
Proximal isovelocity surface area
method – Level 2
MVA = pi (r 2) (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
Valve Anatomy
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
Stress Echocardiography – Level 2
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.
How to Grade Mitral Stenosis
Normal MVA is 4.0-5.0 cm2
MVA >1.5 cm2 does not produce symptoms
As severity increases, cardiac output decreases and fails to
increase during exercise.
Wilkins (Valvotomy )Score
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.
Case 1
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?
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
Continuity equation
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 cm 2 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.
Valvotomy Score = 12
Mobility – valve
moves forward in
diastole, moves
mainly from base
3 points
Subvalvular
Thickening –
thickening of chordal
structures extending
into 1/3rd of the
chordal length
3 points
Thickening – extends
through the entire
leaflet
3 points
Calcification –
Brightness extending
into the mid-portion
of the leaflets
3 points
Total score = 12
Case 2
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.
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
Grade of mitral stenosis: Severe
Resting mean pressure gradient: 16mmHg
(severe is >10mmHg)
Mitral valve area using half time: 0.77cm 2 (severe
is <1.0 cm2 )
PHT: 285 ms (severe is greater than 220ms)
Valvotomy score:
Valvotomy score: 14 out of 16
Mobility: 4 – No or minimal
forward movement of the
leaflets.
Subvalvular Thickening: 2-3Thickening 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.