Anatomy and Pathophysiology of ATOS

The anatomy and pathophysiology of ATOS is centered on cervical and anomalous first ribs. These ribs lie just inferior to the subclavian artery causing the artery to constantly beat against the rib. This results in damage to the inferior wall of the artery which becomes fibrotic and eventually stenotic. If the degree of stenosis elicits vibrations in the range of audible sound, post-stenotic dilatation and aneurysm formation develop in the subclavian artery. Both stenosis and aneurysms can produce non-occlusive arterial thrombosis which is the source of distal emboli and subsequent digital ischemia or even gangrene.