Blood flowing out of the left ventricle must all pass through the valve, so flow in the outflow tract equals flow through the valve. Aortic stenosis is severe when the valve area is below 1.0 cm² (or 0.6 cm²/m² indexed).
How to use the Aortic Valve Area Calculator
- LVOT diameter
- LVOT VTI
- Aortic valve VTI
- Height
- Weight
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the LVOT diameter measured in mid-systole and the velocity-time integrals from pulsed (LVOT) and continuous-wave (valve) Doppler. Mean velocities or peak velocities can be used instead of VTIs.
Inputs explained
| Field | What to enter |
|---|---|
| LVOT diameter | Units: cm, mm |
| LVOT VTI | In cm |
| Aortic valve VTI | In cm |
| Height | Units: cm, in, m, ft, mm |
| Weight | Units: kg, lb, st, g |
What each result means
- LVOT area = pi×([LVOT diameter]÷2)^2
- Aortic valve area = [LVOT area]×[LVOT VTI]÷[Aortic valve VTI]
- Dimensionless index = [LVOT VTI]÷[Aortic valve VTI]
- Indexed AVA = [Aortic valve area]÷sqrt([Height]×[Weight]÷3600)
Example values
How the main result changes when LVOT diameter changes and everything else stays at the example values above:
| LVOT diameter (cm) | Aortic valve area (cm²) |
|---|---|
| 1.05 | 0.22 |
| 1.58 | 0.49 |
| 2.1 | 0.87 |
| 2.63 | 1.35 |
| 3.15 | 1.95 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
LVOT area = π × (LVOT diameter ÷ 2)²
AVA = LVOT area × VTI(LVOT) ÷ VTI(AV)
Dimensionless index = VTI(LVOT) ÷ VTI(AV)
Indexed AVA = AVA ÷ BSA
Worked example
Inputs — LVOT diameter: 2.1 cm; LVOT VTI: 20 cm; Aortic valve VTI: 80 cm; Height: 170 cm; Weight: 75 kg.
Results — LVOT area = 3.46 cm²; Aortic valve area = 0.87 cm²; Dimensionless index = 0.25; Indexed AVA = 0.46 cm²/m².
Key terms
- LVOT
- Left ventricular outflow tract.
- VTI
- Velocity-time integral.
Frequently asked questions
What is a normal aortic valve area?
3–4 cm² in adults.
What is severe aortic stenosis?
Valve area below 1.0 cm², mean gradient above 40 mmHg or peak velocity above 4 m/s.
Why is the LVOT diameter so important?
It is squared, so a 1 mm error changes the area by about 10%.