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125216
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Proximal Isovelocity Surface Area |
Utilizes aliasing velocity (by color Doppler) of flow into an orifice (often regurgitant or stenotic) to measure instantaneous flow rate, orifice area, and flow volume.The instantaneous flow rate = (2πr2vav) * (απ) where vav is the constant velocity known as aliasing velocity at radius r, vpis the peak velocity at the orifice, and α is the angle in radians of the constant velocity surface.Estimated Orifice area = Flow rate / vp, where vp is the peak velocity at the orifice and the flow rate is the PISA peak flow rate.The volume flow is then the product of the orifice area and Velocity Time Integral. |