Subclavian steal syndrome most commonly occurs on which side of the body?

Subclavian steal syndrome is most commonly associated with the left side of the body due to the anatomical configuration of the arteries. The left subclavian artery originates directly from the aortic arch, while the right subclavian artery branches off the brachiocephalic trunk. This difference in origin means that any stenosis or occlusion that occurs in the left subclavian artery can lead to a clinical scenario where blood flow is redirected or "stolen" from the vertebral artery to supply the arm, particularly during physical exertion.

When there is significant narrowing or blockage in the left subclavian artery, the body compensates by reversing flow in the vertebral artery, drawing blood flow away from the posterior circulation of the brain, hence the term "steal." This phenomenon is less commonly observed in the right subclavian artery because of its different anatomical path.

Furthermore, while it is possible for subclavian steal syndrome to occur on either side, it is predominantly seen on the left side due to the reasons outlined above. Hence, the focus on the left side is critical in understanding this condition and its underlying pathophysiology.