Intrathoracic herniation of the liver ('liver-up') is associated with predominant left heart hypoplasia in human fetuses with left diaphragmatic hernia.

OBJECTIVES: Left heart hypoplasia is commonly observed in fetuses with left diaphragmatic hernia. Because in this condition intrathoracic herniation of the liver serves as an important predictor for postnatal disease severity, we studied its potential association with left heart hypoplasia.
METHODS: We prospectively assessed 32 fetuses with left diaphragmatic hernia between 19 + 6 and 38 + 6 weeks of gestation using echocardiography. The fetuses were divided into two groups: Group I exhibited an intrathoracic liver position ('liver-up') and Group II an intra-abdominal liver position ('liver-down'). Cardiac inflow and outflow diameter ratios and cardiac Z-scores were compared between the two groups.
RESULTS: Eleven of the 15 Group I (liver-up) fetuses, but only three of the 17 Group II (liver-down) fetuses with left diaphragmatic hernia exhibited predominant left heart hypoplasia with disproportionately smaller left than right heart dimensions (P = 0.0036). In addition, 14 of the 15 Group I fetuses, but only five of the 17 Group II fetuses exhibited preferential streaming of the ductus venosus towards the right heart (P = 0.0003).
CONCLUSIONS: In fetuses with left diaphragmatic hernia, intrathoracic liver herniation is commonly associated with predominant left heart hypoplasia, whereas an intra-abdominal liver position is not. This observation may be explained by preferential ductus venosus streaming towards the right heart from elevation and leftward distortion of the normal course of the ductus venosus and inferior vena cava.