# Shunt Equation

Calculate
cm
cm
cm
cm
Aortic SV:
Pulmonic SV:
Shunt SV:
Qp/Qs:
Formula: AorticSV = 0.785 * LVOT² * AV VTI; PulmonicSV = 0.785 * RVOT² * PV VTI; ShuntSV = AorticSV - PulmonicSV Qp/Qs = (AorticSV / PulmonicSV) * 100

## How to get a Shunt Fraction (Qp/Qs).

1. Measure the LVOT diameter in centimeters. The optimal view is the mid transgastric LVSAX view.
2. Measure the PWT, SWT, and LVID. 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.
3. 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.
4. 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.
5. 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.