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Aortic Valve Gradient
Calcs>Aortic Stenosis>AVG>1
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Name Value
Vmax of AV (m/s) m/sec
Vmax of LVOT (m/s)  m/sec
Aortic Valve Gradient mmHg
 
Severity Mild Mod Severe
MeanAVG (mmHg)* < 25 25-40 > 40
Mean AVG (mmHg)** < 30 30-50 > 50
Vmax (m/sec) 2.6-3.0 3.0-4.0 > 4.0
AVA (cm2) > 1.5 1.0-1.5 < 1.0
Indexed AVA (cm2/m2) > 0.85 0.60-0.85 < 0.6
Velocity Ratio > 0.5 0.25-0.5 < 0.25
*AHA/ACC Guidelines **ESC Guidelines 

Peak GradientAVG by CE

 
Formula: AVG = 4 x ( VmaxAV)2 - 4 x (VmaxLVOT)2
 
How to get an AVG by Continuity Equation.
 
Step 1: Obtain a continuous wave doppler of the aortic valve. The optimal view is the deep transgastric AVLAX view or the transgastric AVLAX view. The former view is preferable if obtainable. Once the view is obtained turn on the CWD and use the track ball to move the CWD line to the aortic valve. A doppler profile of the aortic valve should be displayed with high velocities in aortic stenosis. If a poor or low velocity doppler wave form is displayed reposition the view and move the CWD line thru out the valve. The CWD must be parallel to the stenotic jet to pick up the maximal velocity and obtain a good doppler wave form. After a good doppler wave form is obtained look at the morphology of the waveform and note it.  A profile that has a large gradient across the valve will exhibit a "filling in" pattern, whereas a low or normal gradient flow profile will have a scattered filled in pattern.  The amount of filling of the flow profile is related to the amount of turbulence across the valve.  Place the trackball point at the peak of the flow profile and note the velocity, Vmax of the Aortic Valve.
 
Step 2: Obtain a pulse wave doppler of the LVOT. The optimal view is the deep transgastric AVLAX view or the transgastric AVLAX view. The former view is preferable if obtainable. Once the view is obtained turn on the PWD and use the track ball to move the PWD line to the LVOT and place the sample volume just proximal to the aortic valve. The sample volume should be at the same location where the LVOT diameter was measured. A doppler profile of the LVOT should be displayed with normal velocities in the LVOT. If a poor or low velocity doppler wave form is displayed reposition the view and move the PWD line thru out the LVOT. The PWD must be parallel to the LVOT jet to pick up the maximal velocity and obtain a good doppler wave form. After a good doppler wave form is obtained look at the morphology and the maximal velocity of the waveform and note it. Using the calipers feature, use the trackball and place the sample at the peak of the LVOT flow profile and note the velocity, which is the reference velocity or Vmax of the LVOT.
 
Step 2(Optional): If you cannot obtain a good PWD profile of the LVOT the CWD profile of the Aortic Valve frequently will exhibit a ghost profile which is contained in the CWD profile. This ghost profile can be used as if it was a PWD profile and entered as the reference velocity or Vmax of the LVOT.
 
Note:  Typically, the PWD of the LVOT will yield a maximum velocity less than 1 m/sec.  Therefore, it's peak gradient is insignificant compared to the aortic valve peak velocity.  In conclusion, it is entirely acceptable to not calculate the LVOT PWD peak velocity.
 
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