Velocity Reversal and Flow Reversal. A. Lower and Upper Normal waveforms indicate a vessel without stenosis. Middle: Complicated velocities in the region of the bifurcation appear dominated by reversed velocity often called "flow separation". B. Systolic reversal in vertebral arteries is a frequent finding. The examining sonographer marked the EAV as the systolic velocity and did not mark an EDV. The UWURC reader marked the negative systolic peak.