Accuracy of intracoronary Doppler ultrasound flow measurements in patients

The accuracy of coronary flow measurements performed in the cardiac catheterization laboratory by means of a Doppler guide wire has been estimated using an indirect method. The average peak velocity (APV) was recorded successively in the 3 branches of 30 arterial bifurcations. Biplane angiograms of these bifurcations were acquired to allow for accurate determination of the relevant cross sectional areas (CSA). The flows were calculated as product “0.5×CSA×APV”. To estimate the flow errors two (mutually exclusive) hypotheses were considered: (A) The mean (unsigned) absolute flow error is the same in the 90 branches. (B) The mean (unsigned) relative flow error is the same in the 90 branches. The second hypothesis proved to better represent the data; the mean relative error varies from 26% for low flow values to 16% for the high flow values