Mitral Stenosis

Sim Session

CASE Presentation

71 year old woman with past medical history of rheumatic heart disease, mitral stenosis and regurgitation s/p mitral commissurotomy in 1970’s and balloon valvuloplasty 5 years ago, paroxysmal atrial fibrillation, hypertension and mild interstitial lung disease reports severe dyspnea at rest.

What is the differential diagnosis of dyspnea in this patient?

Step 1: Evaluate mitral valve in multiple 2D views with and without color flow Doppler:

ME 4 Chamber view
ME Mitral Commissural view
ME 2 Chamber view
ME Long Axis view
TG 2 Chamber view
TG Basal Short Axis view

Calculate the Wilkins score.

Step 2: Evaluate the severity of mitral stenosis

measure mean diastolic gradient
measure MVA using 2D planimetry
calculate MVA using pressure half-time
calculate MVA using continuity equation

Step 3: Evaluate mitral regurgitation

Step 4: Evaluate aortic and tricuspid valves for rheumatic involvement

Step 5: Evaluate sequela of mitral stenosis

measure left atrial size
evaluate pulmonary venous systolic flow
evaluate left atrium and atrial appendage for thrombus
estimate pulmonary artery pressures if tricuspid regurgitation jet present
evaluate right ventricular size and systolic function

Wilkins Score

Score < 9 - optimal result after percutaneous balloon valvuloplasty

Score > 11 - suboptimal result after percutaneous balloon valvuloplasty

Score 9 - 11 - unable to predict the outcome

Wilkins GT, Weyman AE, Abascal VM, et al.: Br Heart J 1988;60:299-308.

Mean Transmitral Pressure Gradient

Mean gradient is determined using Bernoulli equation to average the instantaneous pressure gradients over the diastolic filling period.

Color flow Doppler can help with alignment between the Doppler beam and mitral inflow jet.

PWD may provide a more clearly defined velocity curve, but use CWD if signal aliasing present.

Continuity equation valve area

SV_LVOT = SV_MV

VTI_LVOT * AREA_LVOT = VTI_MV * MVA

MVA = (VTI_LVOT * 2πr_LVOT²) / VTI_MV

VTI_MV - Doppler velocity curve of the antegrade flow across mitral valve

Not accurate if mitral regurgitation present.

Pressure Half-time Valve Area

MVA = 220/pressure half-time (cm²)

220 is empiric constant equivalent to MVA of 1 cm² based on Gorlin valve areas.

The pressure half-time (msec) is the time it takes for the diastolic pressure gradient across mitral valve to decrease by half (NOT the velocity), i.e., time interval between peak velocity and the peak velocity divided by 1.4.

ΔP/2 = (4v²)/2 = 2v/√2 = 2v/1.4 = v/1.4

If there is an initial steeper diastolic slope ("ski-slope" pattern), the pressure half-time should be measured along the flatter mid-diastolic slope.

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