Accuracy of coronary flow measurements performed by means of Doppler wires

nTo estimate in patients the accuracy of coronary flow measurements perform ed by means of 0.014" Doppler wires, the time-averaged maximal blood veloci ty (APV) was recorded in the 3 branches of 36 angiographically normal coron ary artery bifurcations selected in 21 patients undergoing cardiac catheter ization for various diseases. Contrast medium injections filmed under two i ncidences allowed identification of the 3 sample volume locations and compu ting of the 3 corresponding vessel cross-sectional areas (CSA) at subsequen t data analysis. Multiplication of the velocities APV/2 (range: 3 to 20.5 c m/s) by the CSA (obtained by averaging the two calibrated vessel diameters; range: 1.6 to 5.4 mm) yielded 108 flow rates (range: 5.4 to 169 mL/min), T he average relative how error was then estimated using the continuity equat ion (Q(in) = Q(out,1) + Q(out,2)) > and the central limit theorem. The resu lt was that the relative flow error decreased from 30% at Q = 30 mL/min to 13% at Q = 160 mL/min. We conclude that coronary flow measurements are reas onably accurate, except perhaps for very low flows. (C) 2000 World Federati on for Ultrasound in Medicine & Biology.