PULMONARY VASCULAR-RESISTANCE IN COMPLETE ATRIOVENTRICULAR SEPTAL-DEFECT - A COMPARISON BETWEEN CHILDREN WITH AND WITHOUT DOWNS-SYNDROME

Invasive data obtained in children with complete atrioventricular sept al defect over the last three years are presented to determine the age at which pulmonary vascular obstructive disease develops. Comparisons were made between children with (n = 21) and without Down's syndrome (n = 12). The investigation was restricted to patients less than one y ear of age at initial catheterization. Patients with complicated assoc iated heart defects were excluded. Patients with Down's syndrome had a higher ratio of pulmonary to systemic vascular resistance than childr en without Down's syndrome in the basal situation. This difference alm ost disappeared after 100% oxygen had been given to patients with elev ated pulmonary vascular resistance, indicating that hypoxia and/or hyp oventilation is of importance, especially in children with Down's synd rome. Fixed elevated pulmonary vascular resistance was found in 11% of Down patients under one year, with the youngest patient being 5.5 mon ths old. One child without Down's syndrome may have had fixed elevated pulmonary vascular resistance. It is concluded that all children with complete atrioventricular septal defect should be evaluated and opera ted on at a very young age.