Subclavian steal diagnosis: Doppler sonography vs. angiography.

Continuous-wave Doppler sonography is a reliable technique for the diagnosis of subclavian steal. This tool also allows us to identify incipient steals, characterized by either alternating flow or systolic flow deceleration in the vertebral artery, which might escape detection by conventional angiography. Diagnostic criteria are reported and results of a 48-patient study are compared with angiographic data. The different patterns of vertebral flow depend on the degree of proximal subclavian or innominate artery functional stenosis. The Doppler examination is a useful method because it is non invasive, harmless to the patient and allows for the evaluation of associated lesions in other extracranial vessels. It is of particular interest for the diagnosis when the clinical picture is still apparently normal and in the absence of both neurological findings and asymmetrical blood pressure in the arms.