|
|
|
|
| |
| 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 |
|
 
|
| |
| 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. |
| |
