CAN CARDIAC WEIGHT PREDICT LUNG WEIGHT IN PATIENTS WITH CONGENITAL DIAPHRAGMATIC-HERNIA

Left ventricular disproportion (decreased left-to-right ventricular in ternal diameter ratio) has been correlated with fetal or neonatal surv ival in cases of congenital diaphragmatic hernia (CDH). Because cardia c development is intimately related to lung development in the normall y developing fetus, the authors sought to determine whether cardiac we ight correlates with lung weight in control and CDH lambs at term. Twe nty lambs had CDH created surgically at 80 days' gestation and were sa crificed at term for measurement of lung and heart weight. Nine unoper ated lambs served as controls. Analysis of the relationship between he art weight and lung weight was performed for both groups, and regressi on curves were generated as mean +/-2 standard deviations (SD) for eac h group of lambs. All data are expressed in grams. For CDH lambs, the relationship between heart and lung weight is as follows: lung weight = 0.69 x heart weight + 37 g. For control lambs, the equation is: lung weight = -0.004 x heart weight + 135 g. There is no overlap of these regression curves at 2 SD of the mean. The curves differ significantly , and the P value exceeds .05. The results suggest that cardiac weight can be used to predict lung weight in CDH and control lambs at term. The authors speculate that this difference in weight is attributable t o underdevelopment of the left ventricle in CDH. Given that left ventr icular disproportion has been described as early as the pseudoglandula r stage of lung development in human fetuses with CDH, it is hoped tha t echocardiographic parameters can be used to differentiate the fetuse s with adequate lung volume from those whose lung volume is incompatib le with extrauterine life. Patients in the latter group may benefit fr om surgical correction of the diaphragmatic defect in utero. Copyright (C) 1996 by W.B. Saunders Company