Abstract

The structural effect of prostaglandin E1 on the pulmonary circulation in pulmonary atresia has been studied by applying quantitative morphometric techniques to the injected and inflated lungs of eight babies who had received prostaglandin E1 for between 30 hours and 12 days. The most striking effect was on the pulmonary arterial smooth muscle. Relative arterial medial thickness was reduced and muscle did not extend as far along the arterial pathway as compared with the normal and with untreated cases of pulmonary atresia, dying at a similar age. The reduction in muscularity tended to increase the longer the duration of infusion. In all cases the thin arterial media was less compact than normal, and localised aneurysmal dilatations occurred, varying in extent and severity between cases. The preacinar arteries were dilated in comparison with the untreated cases, but, by contrast, the intra-acinar arteries remained abnormally small. The number of intra-acinar arteries per unit area of lung was greater in prostaglandin E1 treated than in untreated cases. Infusion of prostaglandin E1 is now the ideal emergency treatment for pulmonary atresia, but the findings in the present study suggest that it should be given for as short a time as possible before the pulmonary blood flow is increased by surgical treatment.