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Regurgitant Fraction by Continuity Equation
Calcs>Aortic Regurgitation>RF by CE>1
SVAV = CSALVOT x VTIAV
SVAV = 0.785 x DLVOT2 x VTIAV
SVMV = CSAMV x VTIMV
SVMV = 0.785 x DMV2 x VTIMV
RVAR = SVAV - SVMV
RFAR = RVAR / SVAV
to get a Regurgitant Volume in Aortic Regurgitation.
1: Measure the Diameter of the LVOT. The diameter
can be of the LVOT should be obtained from the midesophageal
AVLAX view, in mid systole, and under the zoom mode.
The view of the LVOT should not be an obtuse angle
view. The aortic valve leaflets (NCC and RCC)
should be clearly seen. The zoom mode will decrease
the error present in the calculation. Since
the LVOT diameter changes throughout systole, the mid systole
measurement should be obtained.
2: Obtain a VTI of the LVOT. The
VIT of the LVOT is obtained from a PWD of the LVOT.
The PWD of the LVOT should be obtained at the
same location as the LVOT diameter measurement.
The PWD beam should not be off more than 15Â° from
parallel to the LVOT flow. After tracing the
flow on the echocardiographic machine, a VTI of the
PWD tracing will be calculated. A continuous
wave doppler (CWD) of the LVOT could be obtained,
but, since the CWD introduces ambiguity into the equation
and since flows in the LVOT rarely exceed the aliasing
velocity of the pulse wave doppler, PWD is the best
measurement mode. However, in aortic regurgitation,
there is excessive flow, so aliasing may occur.
Therefore, CWD may be required to be able to trace
the whole flow profile.
3: Obtain a Mitral Valve Diameter. The area
of the mitral valve can be calculated from this measurement.
This enter some inaccuracy into the equation since
the mitral valve is not a circle (it is oval).
Therefore, the pulmonary valve could be used instead.
This measurement is to be used to generate a value
that represents normal forward flow in the cardiac
Step 4: Obtain
a Mitral Valve VTI. Using the PWD mode,
trace the envelope of the entire (E wave and A wave)
flow profile of the mitral valve.
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.