Interrupted Aortic Arch (IAA)

Prostaglandin E1 before anything else - The duct is the only route to the lower body. Start PGE1 as soon as IAA is suspected and never let it lapse; abrupt closure means shock and death. Support shock with inotropes titrated to the clinical response.

Perfusion differs above and below the break - Distal pulses are absent, there is a measurable blood pressure gap between the right arm and the lower extremities, and saturation can differ between the left and right sides of the body. Put pulse oximetry preductally on the right hand and postductally on a foot, and know which side of the interruption your arterial line and cuff are reading before you trust a number.

Send the 22q11.2 workup - Nearly half of IAA patients have a 22q11.2 deletion, so fluorescence in situ hybridization belongs in the workup for all of them. Check the serum calcium, which runs low with the parathyroid hypoplasia of DiGeorge syndrome.

Thymic hypoplasia is a real immune deficit - DiGeorge syndrome produces an absent or hypoplastic thymus and with it T-cell deficiency and recurrent infection; the complete form behaves like severe combined immunodeficiency. Hold strict aseptic technique for lines and airway, and settle blood product requirements with the blood bank before bypass rather than during it.

Airway and other systems - Cleft palate and the abnormal facies of 22q11.2 deletion belong in the airway exam alongside prior anesthetic records. These patients also carry renal, ocular, and gastrointestinal anomalies, so review renal function and the renal ultrasound before nephrotoxic drugs or bypass.

The preoperative picture you should already have - Blood gas showing metabolic acidosis, chest film with cardiomegaly and increased pulmonary markings, ECG with biventricular hypertrophy or right ventricular predominance, and an echo defining the site of interruption. CT or MR angiography is commonly added to map the anatomy before repair.

Know the associated lesions - A ventricular septal defect sits alongside the interruption in roughly three-quarters of cases, often with left ventricular outflow tract obstruction. IAA also travels with transposition of the great arteries, truncus arteriosus, aortopulmonary window, single ventricle, aortic valve atresia, and double-outlet right ventricle - the anesthetic and bypass plan follow from which of these is present.

The repair - Continuity is restored between ascending and descending aorta using native tissue, a homograft, or a vascular patch, with the ventricular septal defect closed by a polyester or ePTFE patch. Some centers stage it: arch reconstruction plus a pulmonary artery band first, VSD closure later. Significant outflow tract obstruction can push the case toward a combined Norwood and Rastelli approach.

Related lesion - IAA and coarctation of the aorta sit on the same spectrum; see the Coarctation of the Aorta entry for the physiology of a narrowed but continuous arch.

Interrupted aortic arch (IAA) is a complete anatomic and luminal discontinuity between the ascending and descending aorta - the most severe end of the coarctation spectrum. It accounts for about 1.5% of congenital heart disease, roughly 2 cases per 100,000 live births, and is grouped by the site of the break under the Celoria and Patton classification.

Everything distal to the interruption is perfused solely through the ductus arteriosus. When the duct closes, usually within the first two weeks of life and often on day one, the lower body loses its supply and the infant develops tachypnea, feeding difficulty, respiratory distress, cyanosis, anuria, metabolic acidosis, and cardiogenic shock.

A posteriorly malaligned conal septum leaves a ventricular septal defect in about 73% of cases and can obstruct the left ventricular outflow tract. Nearly half of these infants carry a 22q11.2 deletion.