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| How
to get a Shunt Fraction (Qp/Qs). |
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| 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. |
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| 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. Using the
tracing feature, use the trackball and trace the doppler
profile. An AV VTI should be calculated. |
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| Step
3: Obtain a RVOT Diameter. The RVIO view is
useful for measuring the RVOT diameter. Under
zoomed conditions, use the trackball-calipers function
to measure the RVOT diameter. |
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| Step
4: Obtain a CWD of the Pulmonary Valve.
The SAX view of the aortic arch will show the pulmonary
valve in long axis view with a good angle for CWD
mode. After the CWD is done, trace the flow
profile of the pulmonary valve and a VTI will be calculated. |
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