Bilateral subclavian steal with steno-occlusive disease of innominate and left subclavian arteries

Simplified schematic of the aortic arch and great vessels, showing typical collateral pathway to supply the right arm in the face of severe steno-occlusive disease of the innominate (brachiocephalic) artery and the left subclavian artery (light green boxes). Flow is reversed in both vertebral arteries, and consequently blood is “stolen” from the vertebrobasilar circulation. Flow is reversed in the basilar artery. Flow may be antegrade or retrograde in the right common carotid artery but remains antegrade (and likely with increased flow) in the left common carotid artery. (Contributed and modified by Dr. Douglas Lanska. Greatly modified from original sketch in Owen E. A Manual of Anatomy for Senior Students. London and New York: Longmans, Green, and Co., 1890.)