What is Subclavian steal syndrome?

Subclavian steal syndrome , also called subclavian steal steno-occlusive disease, is a constellation of signs and symptoms that arise from retrograde blood flow in the vertebral artery or the internal thoracic artery, due to a proximal stenosis and/or occlusion of the subclavian artery. This flow reversal is called the subclavian steal or subclavian steal phenomenon, regardless of signs/symptoms being present. The arm may be supplied by blood flowing in a retrograde direction down the vertebral artery at the expense of the vertebrobasilar circulation. It is more severe than typical vertebrobasilar insufficiency.