Continuity equation (aortic valve area)
EchoEquation
Continuity equation (aortic valve area)
- Aortic valve area
- cm²
- LVOT cross-sectional area
- cm²
- LVOT velocity–time integral (pulsed-wave)
- cm
- Aortic-valve velocity–time integral (continuous-wave)
- cm
GivenLVOT diameter = 2.0 cm → CSA = 3.14 cm², VTI(LVOT) = 20 cm, VTI(AV) = 80 cm
Severe AS (<1.0 cm²)
Conservation of mass: the stroke volume through the LVOT must equal the stroke volume through the valve. Since SV = CSA × VTI, measuring the LVOT and the two velocities lets you solve for valve area.
Conservation of mass
Expand stroke volume
Rearrange for AVA