From the Guidelines
To assess mitral stenosis with transthoracic echocardiography (TTE) based on ASE guidelines, the key steps include obtaining 2D imaging to evaluate valve morphology, measuring mitral valve area using planimetry, calculating mitral valve area using the pressure half-time method, and assessing for concomitant valvular lesions and pulmonary hypertension, as outlined in the 2014 AHA/ACC guideline for the management of patients with valvular heart disease 1. The assessment of mitral stenosis with TTE involves several critical components:
- Obtaining 2D imaging from the parasternal long-axis window to identify the characteristic diastolic doming of the mitral valve, and from the short-axis view to demonstrate commissural fusion and allow planimetry of the mitral orifice, as recommended by the ASE guidelines 1.
- Measuring the mitral valve area using planimetry in the parasternal short-axis view at the tips of the leaflets, which is considered the reference standard, and calculating the mitral valve area using the pressure half-time method, which is inversely related to mitral valve area 1.
- Calculating mean and peak transmitral gradients using continuous-wave Doppler aligned with mitral inflow, and assessing for pulmonary hypertension by measuring tricuspid regurgitation velocity and estimating pulmonary artery systolic pressure, as these reflect the hemodynamic consequences of mitral stenosis 1.
- Evaluating left atrial size and right ventricular function, as these are essential for accurate diagnosis, severity assessment, and appropriate management planning, and assessing for concomitant valvular lesions, particularly mitral regurgitation, as recommended by the ASE guidelines 1. The mitral stenosis severity can be classified based on the valve area and mean gradients, with mild, moderate, and severe categories, and the comprehensive measurements obtained through TTE are crucial for guiding treatment decisions and improving patient outcomes, as emphasized in the 2014 AHA/ACC guideline for the management of patients with valvular heart disease 1.
From the Research
Assessment of Mitral Stenosis with TTE
The American Society of Echocardiography (ASE) guidelines recommend the use of transthoracic echocardiography (TTE) for the assessment of mitral stenosis. The following steps can be used to assess mitral stenosis with TTE:
- Measure the mitral valve area (MVA) using the pressure half-time (PHT) method or two-dimensional planimetry (PLM) method 2, 3
- Measure the proximal isovelocity surface area (PISA) to estimate the MVA 2
- Assess the severity of mitral stenosis based on the MVA and mean transmitral gradient 2, 3
- Evaluate the valve morphology and detect any signs of mitral regurgitation or other valve diseases 4
Measurement of Mitral Valve Area
The MVA can be measured using different methods, including:
- PHT method: measures the time it takes for the pressure gradient across the mitral valve to decrease by half 3
- PLM method: measures the area of the mitral valve orifice using two-dimensional echocardiography 2, 3
- PISA method: measures the area of the proximal isovelocity surface area to estimate the MVA 2
- Three-dimensional direct planimetry: measures the MVA using three-dimensional echocardiography 5, 6
Limitations and Considerations
The accuracy of MVA measurements can be affected by various factors, such as: