The pulmonary vascular bed in children with Down syndrome.

Sixty-nine children with Down syndrome (mongolism, trisomy 21), with atrial septal defect, patent ductus arteriosus, ventricular septal defect, or endocardial cushion defects, and 315 children with similar cardiac anomalies without this syndrome underwent cardiac catheterization during an 8-year period from 1964 to 1973. Only patients under 17 years of age were included in the study. Nine tenths of the children with Down syndrome but only one fourth of the control group had abnormally high pulmonary arterial pressures. For example, 9 of 11 children with defects of the atrial septum and Down syndrome had pulmonary hypertension; in contrast, only 5 of 55 control subjects with similar defects had pulmonary hypertension. The data suggest that children with congenital heart disease and Down syndrome have an unusually high pulmonary vascular resistance and a propensity for early development of severe damage to the pulmonary vascular bed.