Color and pulsed-wave Doppler showing flow in left carotid, vertebral, and subclavian arteries: (a) showing proximal left common carotid artery. There is a relatively normal-appearing Doppler waveform, (b) note mild elevation in peak systolic velocity with plaque at left internal carotid artery origin (arrow). The stenosis is categorized as 40–59% in our laboratory. (c) Showing complete reversal of blood flow in left vertebral artery consistent with complete subclavian steal. (d) Low velocity blood flow with abnormal-appearing Doppler in left subclavian artery consistent with more severe subclavian stenosis proximal to this site.
