Hypertensive pulmonary vascular disease in children. Detection by radioactive nitrogen (13N) inhalation and injection.

Regional lung function has been studied in 16 children with intracardiac shunts and a variety of associated cardiac anomalies using radioactive nitrogen (13N) and a gamma camera-computer system. The distribution and washout of inhaled 13N were usually normal. The distribution of intravenously injected 13N was often abnormal and could be related to local anatomy. The most important finding was delayed clearance by ventilation of intravenously injected 13N in children with an abnormally raised pulmonary/systemic vascular resistance ratio (Rp/Rs) at cardiac catheterisation. The regional localisation of this ventilation-perfusion imbalance could be related in several children to the probable distribution of hypertensive pulmonary vascular disease, predicted either from local anatomy shown at cardiac catheterisation or from the abnormal distribution of pulmonary perfusion. Abnormalities present on breathing air may be partially reversed on breathing 100 per cent oxygen.