When there’s a blockage or narrowing in the
subclavian artery,
blood flow towards the brain may be drawn away, or stolen, from the vertebrobasilar circulation into the subclavian artery. This is known as
subclavian steal syndrome and occurs when blood flows retrograde from the
vertebral or internal thoracic artery, as a result of a proximal narrowing or blockage of the subclavian artery. This syndrome typically affects the left side of the
body due to the anatomical location of the
left subclavian artery. The signs and symptoms of subclavian steal syndrome are usually transient and are more likely to appear when moving the arm vigorously, or when turning the
head in the direction of the affected side. Clinical manifestations include symptoms caused by the reduced blood supply to the brain, such as
dizziness, blurry vision, syncope, or neurological defects; in the arm, decreased blood flow may result in numbness in the arm and
fingertip regions,
reduced blood pressure on the affected side, as well as a differential
pulse and
blood pressure between the arms. Treatment of subclavian steal syndrome involves removing the obstruction from the subclavian artery to restore the blood flow.