Stability of flow patterns in the in vivo post-stenotic velocity field.

Pulsed Doppler velocimetry was used to construct velocity profiles which demonstrated jet flow and recirculation in the poststenotic velocity field of canine peripheral arteries in vivo. Maximal spectral broadening in near midline velocity waveforms was used to assess turbulent type flow disturbance. A doubling or halving of mean volume flow, in iliac and carotid arteries, respectively, had no effect on the spatial relationship of these flow patterns. Peak jet velocity was changed less, and end diastolic velocity was changed more than expected. Magnitude of turbulent type flow disturbance was reduced by halving but not doubling flow. Effects of changes in pulsatility and heart rate are discussed. It is suggested that similar variation in maximum and end diastolic jet velocities and poststenotic spectral broadening will occur in patients undergoing noninvasive diagnostic tests for arterial disease. This will reduce the resolution of methods based on absolute levels of these parameters.