['This study was designed to investigate cytokine and nitric oxide levels in pediatric patients suffering from chronic heart failure and to investigate effects of beta-blocker treatment on these levels.', 'Fifteen infants with heart failure resulting from left-to-right shunts with pulmonary overcirculation were compared with 11 infants with cyanotic heart defects with reduced pulmonary blood flow. Four of these patients were finally treated with the beta-blocker propranolol.', 'Endogenous nitric oxide production was determined by measuring total plasma nitrite/nitrate (Griess method), and levels of soluble tumor necrosis factor receptors type 1 and type 2 (TNF-R1 and TNF-R2, respectively) were measured by commercially available enzyme-linked immunosorbent assay.', 'In infants with left-to-right shunts, soluble tumor necrosis factor receptor levels were significantly elevated as compared with infants with cyanosis (TNF-R1: 1.7 +/- 0.5 vs. 0.8 +/- 0.3 ng/mL; p =.0003; TNF-R2: 8.1 +/- 4.0 vs. 5.1 +/- 3.2 ng/mL; p =.049). In addition, we found a significant correlation between nitrate/nitrite levels and TNF-R1 (r =.70; p =.0001) or TNF-R2 (r =.62; p =.0013), respectively. Furthermore, the tumor necrosis factor receptor levels in four children after beta-blocker treatment were lower as compared with levels before beta-blocker treatment.'] Are endogenous nitric oxide and soluble tumor necrosis factor receptor levels enhanced in infants with congenital heart disease?