Critical coarctation of the aorta

Coarctation of the aorta is a narrowing of the descending aorta. The narrowing typically is at the isthmus, the segment just distal to the left subclavian artery. In critical coarctation, the narrowing is severe and blood flow to the descending aorta is dependent on a PDA. When the PDA closes, neonates with critical coarctation develop heart failure and/or shock. On physical examination, femoral pulses are weak or absent.