Coarctation and other obstructive aortic arch anomalies: their relationship to the ductus arteriosus.

Forty-three specimens with an obstructive aortic arch anomaly, obtained from infants that had died under the age of one year, were studied to establish the relationship between the arch anomalies and the ductus arteriosus. All specimens were studied morphologically. Twenty of the 43 were also studied histologically. The morphological part of the study included measurements of all the segments of the aortic arch and establishment of the localisation of any associated coarctation. The specimens were divided according to the appearance of the isthmus. The isthmus was not present in 4, was atretic in 2, hypoplastic in 19 and had a normal diameter in 18 cases. In all cases, except 5 (2 with atresia and 3 with hypoplasia of the isthmus) there was an associated coarctation. The majority of the coarctations (28) was located preductally. All such preductal coarctations had ductal tissue in the obstructing ridge. There were 5 paraductal coarctations. Of these, two also had ductal tissue in the ridge. The distribution of the ductal tissue among the two types of coarctation suggested a spectrum of anomalies rather than two completely different entities. The patterns of the aortic arches appeared predictive for the type of coarctation present. The arches that tapered normally towards the isthmus either presented with a preductal coarctation (20 cases) or without a coarctation (3 cases). All 4 specimens in which the isthmus was lacking also had a preductal coarctation. The 5 paraductal coarctations were found in arches that showed a "reverse" pattern, tapering towards the brachiocephalic arteries. All the preductal coarctations contained ductal tissue whereas only 2 of the 5 paraductal coarctations had ductal tissue in the obstructing ridge. It is concluded that careful evaluation of all the segments of the aortic arch may be helpful in the clinical evaluation of infants with an obstructive aortic arch anomaly.