Aortic valve area calculator: continuity equation and stress echo
Explore aortic valve area with the continuity equation, the required LVOT and aortic Doppler measurements, and the tool’s stress-echo options.
Method
AVA = LVOT area × LVOT VTI ÷ AV 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
Measurement
Enter the measured value in the displayed unit
- Resting continuity
- Stress comparison
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
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.
Aortic valve 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.
Body surface area m²
Record the units, date and measurement source
- Use measured height and weight where feasible. Record the units, date and whether a value was reported or estimated.
- Fluid status and weight changes affect BSA. Document any substituted weight; do not silently replace measured weight with ideal or dry weight.
- Use the unit named by the field. BSA is in m²; height and weight can be converted in the Body surface area calculator. Keep the formula with serial indexed results.
Peak AV velocity m/s
Continuous-wave Doppler
- Align the CW cursor as parallel as possible to the jet.
- Acquire a dense, complete envelope without truncation.
- Measure the highest absolute velocity on the selected envelope.
Mean AV gradient mmHg
Complete traced CW envelope
- Align through the valve or shunt and record a complete envelope.
- Trace the modal velocity envelope using the machine tool.
- Use the machine-calculated mean gradient in mmHg.
LVEF category
Enter the measured value in the displayed unit
- Preserved · ≥50%
- Reduced · <50%
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Rest · stroke volume mL
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Stress · stroke volume mL
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Rest · AVA cm²
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Stress · AVA cm²
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Rest · mean gradient mmHg
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Stress · mean gradient mmHg
Enter the measured value in the displayed unit
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Rest · ejection time ms
Enter the measured value in the displayed unit · Optional
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Stress · ejection time ms
Enter the measured value in the displayed unit · Optional
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Stage acquisitions
Enter the measured value in the displayed unit
- Matched & reliable
- Not comparable
- Uncertain
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.
Sources and method context
European Association of Cardiovascular Imaging and American Society of Echocardiography · 2017 · Recommendations on the Echocardiographic Assessment of Aortic Valve Stenosis: A Focused Update · Continuity equation and acquisition pp. 4–11 · Table 3 p. 12 · discordant AS pp. 12–15 · integrated pathway and Figure 8 pp. 16–17
- Continuity equation & acquisition · Sections on peak velocity, mean gradient and AVA · PDF pp. 4–11
Multiwindow CW acquisition, LVOT diameter and PW sampling, continuity-derived AVA, indexed AVA, and velocity/VTI ratio.
- Hemodynamic ranges · Table 3 · PDF p. 12
Peak velocity, mean gradient, AVA, indexed AVA, and velocity-ratio ranges and boundary conventions.
- Flow-aware discordance and stress comparison · Discordant-AS sections pp. 12–15 · Figure 8 and integrated pathway pp. 16–17
Resting discordance pathway and DSE acquisition/reporting, PDF pp.13–14: same baseline LVOT diameter, stage SV/area/gradient comparison, >20% SV reserve and projected area at 250 mL/s. Projection equation and ≥15% Q-change condition: Ferreira et al., Arq Bras Cardiol 2018;110:132–139, Methods/Discussion, doi:10.5935/abc.20180018.
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.
Keep exploring
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- Apical three chamber (apical long axis) acquisition guide · Open in Probe Lab
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