Carotid steal syndrome: a case study.

The progression of subclavian arterial stenosis and the subsequent formation of collateral pathways serve to alter the pressure gradients in subclavian steal syndrome, altering ipsilateral vertebral artery flow from its normal state to "latent," "transient," and "continuous" steals. A similar altered flow in the carotid arteries can be observed with stenosis of the proximal common or innominate artery. A 59-year-old man was seen in the vascular laboratory for evaluation of symptomatic peripheral arterial disease. An incidental asymptomatic stenosis of the right innominate and left proximal subclavian artery was found. Further cerebral vascular evaluation displayed a continuous right subclavian steal and a latent steal in the right internal carotid artery. Transcranial Doppler examination displayed "transient" steal in the terminal right internal carotid artery. Combining duplex and transcranial Doppler evaluations allows sequential evaluation of the progression of arterial disease and its effect on the flow patterns in the cerebral vasculature.