[1] In this condition, the affected arm may receive blood supply flowing in a retrograde direction down the vertebral artery, potentially compromising the vertebrobasilar circulation.

Inflammation leaves behind dense scar tissue, which can become stenotic and restrict blood flow.

[4] SSS can be iatrogenic, meaning a complication or side effect of medical treatment, one example being the obstructive fibrosis or thrombosis resulting from repair of aortic coarctation.

[10] As a result of this procedure, the distal end of the ITA is diverted to one of the coronary arteries (typically the LAD), facilitating blood supply to the heart.

In the setting of increased resistance in the proximal subclavian artery, blood may flow backward away from the heart along the ITA, causing myocardial ischemia due to coronary steal.

Resistance is affected by the length and width of a vessel (i.e. a long, narrow vessel has the greatest resistance and a short, wide one the least), but crucially, in the human body, width is generally more limiting than length because of Poiseuille's Law.