Examples of duct dependent circulations include critical coarctation of the aorta (duct dependent systemic circulation) or pulmonary atresia (duct dependent pulmonary circulation). In critical coarctation there is extreme narrowing of the aorta just where the arterial duct joins the aorta, and blood supply to the lower half of the body is only possible if it passes from the pulmonary artery to the descending aorta via the duct. In pulmonary atresia, the only blood supply to the lungs is that which passes from the aorta to the pulmonary artery via the duct. Continued survival of these babies requires infusion of.
