Aortic Stenosis Calculator

 

 

Using the Continuity Equation:

Input the following: (either VTIs or peak velocity can be used)

LVOT diameter: cm
LVOT VTI:
cm
LVOT peak velocity:
meters/s
Aortic Valve VTI: cm
Aortic Valve peak velocity:
meters/s
Aortic Valve Area (by VTI): cm^2
Aortic Valve Area (by peak velocity)
: cm^2

Category
Mild AS
Moderate AS
Severe AS
Valve Area (cm^2)
>1.5
1.0-1.5
<1.0
Peak Jet Velocity (m/s)
<3
3-4
>4
Mean Gradient (mmHg)*
<25
25-40
>40
Source: ACC/AHA guidelines 2006. Guidelines for the Management of Patients With Valvular Heart Disease. Circulation 2006;114;450-527
*beware of low gradients in cases of severe aortic stenosis with diminished LV function Additional testing is needed to assess severity. (see section on aortic stenosis).

 

Description and Example:

To calculate Aortic Valve Area by the continuity equation you need the following:

1) LVOT diameter from the PLAX view (in most people this is near 2 cm). This is assumed to be constant throughout systole.

2) LVOT velocity and/or VTI from the 5 chamber or apical long axis view.

3) The velocity of VTI at the aortic valve from the 5 chamber or apical long axis view.

 

 

By the continuity Equation: Area1xVTI1 = Area2x VTI2
LVOT Area x LVOT VTI = AV Area x AV VTI 3.14(2.0cm/2)2 x 19cm = AV Area x 82.1cm AV area =
Area = 0.72cm2, which along with the high mean gradient and peak jet velocity is consistent with severe aortic stenosis.