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Formulas:
LVOT-CSA = 0.785 * LVOT-Diam2
TV-CSA = 0.785 * TV-Diam2
LVOT-SV = LVOT-CSA * LVOT-VTI
TV-SV = TV-CSA * TV-VTI
RV = TV-SV - LVOT-SV
RF = RV / TV-SV
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| How to
get a Regurgitant Fraction in Tricuspid Regurgitation.
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| Step 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. |
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| Step 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 15° 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. |
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| Step 3: Obtain
a Tricuspid Valve Diameter. The area of the tricuspid
valve can be calculated from this measurement.
This may enter some inaccuracy into the equation since
the tricuspid valve is not a circle (it is oval).
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| Step 4: Obtain
a Tricuspid Valve VTI. Using the PWD
mode, trace the envelope of the entire (E wave and
A wave) flow profile of the tricupsid valve. |
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