Can Ultrasound detect subclavian steal syndrome ?
A routine component of the carotid artery US examination is demonstration of the patency, direction of flow, and waveform of the vertebral arteries in the neck. Normally, the vertebral arteries demonstrate monophasic antegrade flow toward the head. Biphasic or complete reversal of flow away from the head in the vertebral artery is an indication of subclavian artery stenosis proximal to the origin of the vertebral artery. In this case, the subclavian artery “steals” blood from the ipsilateral vertebral artery with retrograde flow down the vertebral artery supplying the subclavian artery distal to the point of subclavian stenosis.