Isolated innominate artery as a cause of subclavian steal and cerebral hemisphere atrophy.

A rare case of isolated innominate artery arising from a left persistent arterial duct with a right aortic arch is presented. Of interest in this case is the retrograde flow in the left carotid system, the history of developmental delay, and the magnetic resonance image (MRI) brain findings suggestive of asymmetric volume loss affecting the left cerebral hemisphere. The authors postulate a possible mechanism of subclavian steal.