How this calculator works
The continuity equation equates flow through the left ventricular outflow tract and aortic valve. A circular LVOT cross-section and matching stroke-volume measurements are assumed. Diameter is squared, so small measurement errors have a large effect. Valve area alone cannot establish stenosis severity in low flow or discordant studies. The result is an estimate for information only and is not medical advice.
Formula
AVA = π(D/2)² × VTI_LVOT / VTI_AV. Diameter and both VTIs must use compatible length units; area is reported in cm².
Worked example
A 2 cm LVOT with VTI 20 cm and aortic VTI 80 cm gives AVA 0.7854 cm². With aortic VTI 40 cm it gives 1.5708 cm².
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Frequently asked questions
Can I substitute peak velocities?
The VTI formulation compares integrated flow. Do not mix a peak velocity with a VTI.
Why is diameter important?
A 10% diameter error produces about a 21% cross-sectional area error.
Does this determine whether a procedure is needed?
No. Symptoms, gradients, flow and imaging quality must be assessed together.