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Aortic Valve Area by Velocity Ratio
Calcs>Aortic Stenosis>AVA by Velocity Ratio>1
CSALVOT = 0.785 x LVOTd2
AVA = CSALVOT x LVOTVmax / AVVmax
How to get
an AVA by Continuity Equation.
Step 1: Measure
the LVOT diameter in centimeters. The optimal view is a maximally
zoomed view of the midesophageal AVLAX. The gain and compress should
be set so the endomyocardial wall of the LVOT is clearly discernable.
Freeze the display and use the trackball to cycle thru the cardiac
cycle to the mid-ejection period when the LVOT is at it's maximal
diameter. Using the calipers, measure from intimal wall to intimal
wall just proximal to the aortic valve. Activate the Aortic Valve
analysis package and select LVOT diameter and enter the value
of the LVOT diameter.
Step 2: 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. Valvular aortic stenosis has a
uniform increase and decrease in the velocity profile. Aortic
Stenosis from IHSS has a dagger shaped velocity profile. Using
the tracing feature, use the trackball and trace the doppler profile.
The maximum velocity, Vmax, for the AV should be enter above.
Step 3: 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 tracing feature, use the trackball and trace
the doppler profile. The maximum velocity, Vmax, for the LVOT should
be entered above.
Step 3 (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 traced
as if it was a PWD profile and entered as the Vmax of the LVOT.
This activity has been planned and implemented in accordance with the accreditation requirements and policies of the Accreditation Council for Continuing Medical Education through the joint providership of University of Nebraska Medical Center, Center for Continuing Education and JLS Interactive, LLC.
The University of Nebraska Medical Center, Center for Continuing Education is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.
This activity is approved by the American Society of Radiologic Technologists (ASRT) as sonography-related continuing education (CE). Credit(s) issued for successful completion of ASRT-approved CE activities are accepted by the American Registry of Diagnostic Medical Sonography, American Registry of Radiological Technologists, Cardiovascular Credentialing International and Canadian Association of Registered Diagnostic Ultrasound Professionals. Contact the applicable registry for additional information / restrictions on their acceptance of ASRT CE credit.