The ductus arterious and associated cardiac anomalies in interruption of the aortic arch

Seventeen heart specimens with aortic arch interruption, a ductus-dependent anomaly, were investigated. In all specimens the cardiac anatomy favoured a preferential flow into the pulmonary artery (from which the blood could reach the descending aorta through the ductus). Ten specimens had the interruption proximal to the left subclavian artery (type B) and nine of these presented solely with an outflow tract septal defect. On the other hand, six of seven specimens with the interruption distal to the left subclavian artery (type A) were associated with more complex heart malformations. The ductus was studied histologically in the 12 available arches without surgical intervention. The structure of the ductal wall, the components of which could extend considerably into the descending aorta and the pulmonary artery, ranged from that seen in a normal, mature ductus with prominent intimal cushions, to a totally abnormal persistent type with no intimal cushions and with marked elastification. This variability in ductal wall structure and the distribution of ductal tissue in the descending aorta and pulmonary artery has clinical and surgical consequences.