Inferior Rib Notching Mechanics of Coarctation of Aorta

A classic radiographic feature Coarctation of Aorta is inferior rib notching, typically involving the 3rd to 9th posterior ribs bilaterally.

• Mechanism: enlarged intercostal arteries continuously press against the ribs while providing collateral blood flow to bypass the aortic obstruction.

• The first and second ribs are classically spared because their intercostal arteries arise from subclavian arteries rather than the aorta.

• Unilateral right-sided rib notching specifically indicates that the coarctation is located at, or proximal to, the origin of the left subclavian artery.