Remodeling of pulmonary arteries in human congenital diaphragmatic hernia with or without extracorporeal membrane oxygenation

Purpose: The aim of this study was to describe in detail the perinatal deve lopmental profile of the pulmonary vasculature in congenital diaphragmatic hernia (CDH) and to examine the potential beneficial effects of extracorpor eal membrane oxygenation (ECMO) on the vascular morphology. Additionally th e authors aimed to identify the differences in pulmonary vascular morpholog y among CDH cases according to the primary cause of death: either extreme l ung hypoplasia (LH) or persistent pulmonary hypertension (PPH). Methods: The authors studied autopsy sections from 30 high-risk CDH cases w ith respect to the pulmonary arteries in relation to gestational age (GA) a nd ECMO treatment. They were grouped into CDH-I: 20 cases with GA greater t han 34 weeks who were not subjected to ECMO and CDH-II: 10 cases with GA gr eater than 34 weeks, who were subjected to ECMO for an average time of 237 hours. Five age-matched neonates who died from placental insufficiency or b irth asphyxia without evidence of lung hypoplasia served as controls (CON). Medial and adventitial thicknesses of pulmonary arteries were measured in lung sections stained with Elastic van Gieson by 2 investigators blinded fo r the clinical data. Immunohistological staining with anti-a-smooth muscle actin (alpha-SMA) was performed to confirm the precise location of the arte rial media before morphometry. CDH cases were subgrouped and compared accor ding to the primary cause of death. Unpaired Student t test was used for st atistics, with significant P value less than or equal to.05. Results: In CDH newborns, a significant increase in medial, adventitial, an d total wall thickness was found in pulmonary arteries with an external dia meter of less than 200 mu m as compared with age-matched controls (P<.004, .0001, and .0009, respectively). ECMO-treated CDH newborns showed a signifi cantly thinner arterial adventitia than CDH patients who did not receive th is treatment (P<.0001), approaching normal values. However, the medial thic kness remained increased. Morphometrically, no significant differences in C DH cases between patients dying of PPH or severe LH could be determined. Conclusions: (1) In CDH, there is failure of the normal arterial remodeling processes occurring in the perinatal period. (2) Pulmonary vascular morpho logy in CDH does not differ between the groups with lung hypoplasia or pers istent pulmonary hypertension as primary cause of death. (3) Adventitial th inning of these arteries might be one of the mechanisms by which ECMO alter s PPH in CDH cases. J Pediatr Surg 35:208-215. Copyright (C) 2000 by W.B. S aunders Company.