FIG 2. Characterization of Doppler waveform at different zones along the stenotic artery (65% reduced area). Flow of RBC suspension displayed a normal Doppler velocity profile at the prestenosis zone. However, at the stenosis zone, the flow showed a sharp increase in systolic velocity and the signal intensity started to distribute unevenly; at poststenosis I zone, the velocity tended to decrease, but a high intensity turbulent signal in the central waveform and apparent reversal flow became notable. The flow profile at poststenosis zone II returned to normal but had a lower systolic velocity.