Nitric oxide-related compounds in patients with congenital heart defects and pulmonary hypertension

Background: The relationship between blood levels of nitric oxide (NO)-rela ted compounds in patients with congenital heart defects (CHD) and degree of pulmonary hypertension (PH) has not yet been described. Methods: Thirty-six patients (aged 6 months to 19 years) with CHD were divi ded into three groups on the basis of their hemodynamic characteristics: gr oup 1 (control, n=5), left-to-right shunt (-) without PH (pulmonary to syst emic artery peak pressure ratio, Pp/Ps < 0.4); group 2 (n=14), left-to-righ t shunt (+) without PH; group 3 (n=17), left-to-right shunt (+) with PH (Pp /Ps > 0.4). Blood samples were obtained from the right atrium, pulmonary ar tery, left atrium or pulmonary capillary wedge and aorta during cardiac cat heterization. All NO-related compounds in whole blood were measured by chem iluminescent assay using Sievers NO analyzer. Results: The sampling site had no significant impact on NO-related compound levels. However, the patients with PH (group 3) had significantly higher ( P < 0.01) blood levels of NO-related compounds (117.3+/-14.7 mu mol/L) than the patients without PH (groups 1 and 2, 23.9+/-3.2 and 38.4+/-4.8 mu mol/ L, respectively). In addition, pulmonary artery resistance (Rp) values of l ess than 6 Wood U/m(2) were directly correlated with levels of NO-related c ompounds, whereas Rp values greater than 6 Wood U/m(2) were inversely corre lated with blood levels of NO-related compounds. Conclusion: The present results suggest that the hemodynamic status of the pulmonary circulation in CHD affects, at least partly, blood levels of NO-r elated compounds.