This is a rare anomaly characterized by a buckling or kinking of the descending aorta at the level of the ligamentum arteriosum, without significant hemodynamic obstruction or pressure gradient across the lesion, and therefore no collateral vessel formation.

Embryologic theory: failure of compression and fusion of the third through tenth segments of the dorsal aortic roots and of the left fourth arch segment when the cephalic shift of the seventh dorsal intersegmental artery occurs. As a result, the aortic arch is longer than normal, and eventually twists or kinks at the point of insertion of the ligamentum arteriosum. Pseudocoarctation may also result from a short, taut ligamentum arteriosum or PDA. 

This entity is usually asymptomatic and does not need interventional treatment in most of the cases.