True shape and area of proximal isovelocity surface area (PISA) when flow convergence is hemispherical in valvular regurgitation.

摘要: Abstract The proximal isovelocity surface area (PISA) method for quantifying valvular regurgitation uses an echocardiographic image with superimposed colour Doppler mapping to visualise the contours of velocity in blood travelling towards regurgitant orifice. flux through orifice is obtained as product one these (presumed hemispherical) and speed passing it. However, measures component echo probe (vcosθ) rather than ( v ), so that equal (isodoppler contours) differ from isospeed contours. We derive shape isodoppler contour obtainable by mapping, show its much less hemispherical contour. When derived appropriate single measure dimension, result may be obtained. if true measured directly, will substantially underestimated. Indeed, conditions necessary are extraordinary. should not therefore make deductions apparent convergence zone without considering principles which generated. discrepancy assume practical significance when increased resolution technology makes measurement feasible. Assuming flow indeed hemispherical, a ‘correction' factor 1.45 would required.