Interrupted aortic arch (IAA) is a rare and severe congenital heart condition in which the aorta is completely discontinuous: there is a segment missing, so that the ascending and descending aorta are not connected. Blood flow to the lower body therefore depends entirely on the ductus arteriosus, a fetal blood vessel that normally closes within the first few days after birth. IAA is considered a more severe form of coarctation of the aorta. A large ventricular septal defect (VSD) is present in almost all cases, and other cardiac abnormalities, including aortic valve abnormalities and subaortic obstruction, are frequently associated.
When the ductus arteriosus begins to close after birth, babies with IAA deteriorate rapidly. The lower body becomes deprived of oxygenated blood, causing cardiovascular collapse, metabolic acidosis, and renal and intestinal ischaemia. Affected newborns present with a difference in pulses and blood pressure between the upper and lower body, grey or mottled skin, and signs of shock. IAA is a neonatal cardiac emergency.
Immediate management involves intravenous prostaglandin E1 to reopen and maintain the ductus arteriosus, restoring blood flow to the lower body while the baby is stabilised. Surgical repair is then undertaken, typically in the first few days of life, and involves connecting the two ends of the aorta and closing the VSD. The operation requires cardiopulmonary bypass and is performed at specialist paediatric cardiac surgical centres.
Long-term outcomes have improved significantly with modern surgical techniques, but survivors require lifelong follow-up in adult congenital heart disease (ACHD) services. Recurrent arch obstruction, aortic valve disease, left ventricular outflow tract obstruction, and hypertension are recognised late complications. IAA is associated with DiGeorge syndrome (22q11.2 deletion) in approximately 50% of cases, and genetic testing is part of routine evaluation.
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