Angiocardiographic morphology and associated cardiac anomalies of the
coarctation of the aorta (
COA) were analysed in the light of recently advanced theory of its morphogenesis. Analysis of 154 clinical cases of
COA revealed the presence of associated cardiac anomalies which could obstruct fetal blood flow to the ascending aorta in many cases. Systolic left ventricular outflow tract was significantly narrow in cases of
ventricular septal defect (VSD) associated with
COA in comparison with the isolated VSD (p less than 0.01). Good quality aortograms obtained from 41 cases of
COA were analysed. Ages ranged from one month to 20 years and major cardiac anomalies were associated in 25 cases. Age-matched 37 cases were studied as the controls. In
COA, the isthmus was narrower than the controls in 88% of the cases, and in the remaining it was low in the normal range. Severely hypoplastic isthmus in early infancy became the adult type after 5 years in one of the 4 cases which had repeated aortography. Localized
stenosis at the distal end of isthmus was present in 89%, and absent in 11% (4 cases). In these 4, isthmal narrowing was associated with major intracardiac anomalies, large
patent ductus arteriosus (PDA) and
pulmonary hypertension (PH). The anterior ostium to the descending aorta was obstructed by constricted ductus arteriosus (PDA) and
pulmonary hypertension (PH). The anterior ostium to the descending aorta was obstructed by constricted ductus arteriosus in some infants with
COA. These angiographic findings are compatible with the following working hypothesis: ischemic hypoplasia results from prenatal decrease of blood flow to the ascending aorta, and localized
stenosis is related to abnormal distribution of the ductal tissue to the descending aorta and post-natal constriction of the ductus arteriosus. In 3 infants
COA was associated with persistent fifth aortic arch.