Description and Example:

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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.

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By the continuity Equation:

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Area1xVTI1 = Area2x VTI2 

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LVOT Area x LVOT VTI = AV Area x AV VTI

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3.14(2.0cm/2)^2 x 24cm = AV Area x 124cm 

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AV Area = 0.6cm^2, which is consistent with severe aortic stenosis.