Mitral valve area calculator: continuity equation
Review the flow and mitral inflow measurements used by the continuity-equation tool for mitral valve area.
Method
MVA = LVOT area × LVOT VTI ÷ MV VTI
Use the measurement units shown below. Some fields apply only to a selected method or condition; follow the interactive tool’s method choices. The interactive tool keeps missing measurements incomplete and provides its method-specific results and reference context.
Measurements and acquisition
LVOT diameter cm
2D echo · inner-edge measurement
- Use the specified view and cardiac phase.
- Align the calipers perpendicular to the structure’s long axis.
- Measure inner edge to inner edge and avoid oblique foreshortening.
LVOT VTI cm
Pulsed-wave Doppler
- Place the sample volume at the specified annulus or outflow tract.
- Align the Doppler beam with flow and record a clean envelope.
- Trace the modal velocity envelope and use the reported VTI.
Mitral inflow VTI cm
Continuous-wave Doppler trace
- Use the same aligned CW recording as the peak velocity.
- Trace the outer edge of the dense envelope for the relevant phase.
- Use the machine-reported VTI in centimeters.
Sources and method context
American Society of Echocardiography · 2023 · Recommendations for the Use of Echocardiography in the Evaluation of Rheumatic Heart Disease · Continuity equation and exclusions p. 6 · alternative methods and recommendation p. 7 · Table 1 p. 6
- Equation & paired acquisition · Continuity method · PDF p. 6
MVA from LVOT cross-sectional area times LVOT VTI divided by mitral VTI, with RVOT/pulmonic substitution when isolated AR is present.
- Method limitations · Continuity method · PDF pp. 6–7
Compounded measurement error, limited validation, infrequent use, and invalidity with important MR or AR when an appropriate competent reference is not used.
- Severity & clinical role · Table 1 p. 6 · alternative-method recommendation p. 7
Current MVA grades and use only as a corroborating method when planimetry, PHT, and mean gradient are inconclusive.
Catalogue review status: Exact guideline locator mapped · clinical sign-off pending
These pages describe the educational tool. Interpret measurements with the complete clinical context and the method’s acquisition limitations.
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