Aortic Valve Area Calculator
Estimate aortic valve area three ways — the echo continuity equation and the cath-lab Gorlin and Hakki equations — and grade stenosis severity.
The three aortic valve area equations
Aortic valve area (AVA) can be derived three ways — echo (continuity) or invasively in the cath lab (Gorlin, Hakki):
- Continuity: AVA = LVOT diameter² × 0.7854 × LVOT VTI ÷ aortic valve VTI
- Gorlin: AVA = cardiac output(mL/min) ÷ (heart rate × systolic ejection period × 44.3 × √mean gradient)
- Hakki: AVA = cardiac output(L/min) ÷ √(peak-to-peak gradient) — a quick approximation of Gorlin
Aortic stenosis severity by valve area
| Valve area (cm²) | Severity |
|---|---|
| > 1.5 | Mild |
| 1.0–1.5 | Moderate |
| < 1.0 | Severe |
See valve gradients in the hemodynamics guide.
Frequently asked questions
How do you calculate aortic valve area?
Three equations are used: the echo continuity equation (LVOT diameter² × 0.7854 × LVOT VTI ÷ aortic valve VTI), and the invasive Gorlin and Hakki equations from cath-lab cardiac output and gradient.
What aortic valve area is severe stenosis?
An aortic valve area under 1.0 cm² indicates severe aortic stenosis; 1.0–1.5 cm² is moderate and above 1.5 cm² is mild.
What is the difference between the Gorlin and Hakki equations?
Gorlin uses cardiac output, heart rate, systolic ejection period, and mean gradient; Hakki is a simplified approximation, cardiac output divided by the square root of the peak-to-peak gradient.
What is the continuity equation for aortic valve area?
AVA = LVOT diameter² × 0.7854 × LVOT VTI ÷ aortic valve VTI, measured on echocardiography.