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Pulmonary Valve Gradient
Calcs>Pulmonary Stenosis>PVG>1
Calculator
How
to get an PVG by Peak Velocity.
Step
1: Obtain a continuous wave doppler of the pulmonary
valve. The optimal view is the short axis of the
aortic arch. In this view the pulmonary valve
is in it's long axis and provides the best angle to
doppler the gradient's across the valve. An
alternative view is the deep transgastric view around
90 degrees. The pulmonic valve should be viewable
in most instances, however, the angle for the doppler
scan may be off more than 20 degrees. Once the
view is obtained turn on the CWD and use the track
ball to move the CWD line to the pulmonary valve.
A doppler profile of the pulmonary valve should be
displayed with high velocities in pulmonary 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.
Step
2: Obtain a pulse wave doppler of the RVOT.
The views listed above will provide a RVOT scan, however,
the deep transgastric is preferable because of a more
accurate scan. Once the view is obtained turn
on the PWD and use the track ball to move the PWD
line to the RVOT and place the sample volume just
proximal to the pulmonic valve. The sample volume
should be at the same location where the RVOT diameter
was measured. A doppler profile of the RVOT should
be displayed with normal velocities in the RVOT. If
a poor or low velocity doppler wave form is displayed
reposition the view and move the PWD line thru out
the RVOT. The PWD must be parallel to the RVOT 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 RVOT flow profile and note the velocity,
which is the reference velocity.
Note:
Typically, the PWD of the RVOT 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 RVOT PWD peak velocity.
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.