Plasma endothelin-1 and nitrate levels in Down's syndrome with complete atrioventricular septal defect-associated pulmonary hypertension: a comparison with non-Down's syndrome children.

Children with Down's syndrome (DS)-associated complete atrioventricular septal defect (AVSD) have rapid and aggressive development of pulmonary vascular disease when compared with non-Down's syndrome (ND) children. We aimed to evaluate the role of plasma endothelin-1 (ET-1) and nitrate levels in DS children with complete AVSD-associated pulmonary hypertension (PH) and compare this to ND patients. The study included 20 patients (11 males, nine females) who had complete AVSD associated with PH. Comparisons were made between DS patients (n=12) aged 4 to 8 months (median 5 months) and ND patients (n=8) aged 4 to 12 months (median 7 months). Blood samples were drawn from the inferior vena cava, pulmonary artery, pulmonary vein, and aorta. The plasma ET-1 concentrations of the two groups were compared to the peripheral venous and arterial ET-1 levels, and pulmonary vein nitrate was compared to the peripheral arterial nitrate levels of ten healthy infants. The mean pulmonary artery (PA) pressure and pulmonary vascular resistance (Rp) were significantly higher in the DS group than ND patients, and the pulmonary blood flow (Qp) in ND patients was higher than DS patients. There were no differences between the two study groups in regard to plasma ET-1 and nitrate levels obtained from matched sampling sites. The plasma ET-1 and nitrate levels were significantly higher in both study groups compared to the control subjects. The plasma ET-1 and nitrate levels in DS patients with PH were not different when compared to those of ND patients.