Purpose: Predominant left heart hypoplasia is commonly observed in human fetuses with left diaphragmatic hernia and intrathoracic liver herniation ("liver-up"). In contrast, marked left/right heart disproportion has not been described in fetuses with right diaphragmatic hernia, despite intrathoracic herniation of large parts of the liver.
Patients and methods: We analyzed the data of 15 fetuses with left diaphragmatic hernia and 10 fetuses with right diaphragmatic hernia and all with intrathoracic liver herniation ("liver-up") that were examined with fetal echocardiography between 21 weeks + 1 day and 35 weeks + 0 days of gestation. The inflow and outflow dimensions and Z-scores of the two groups were statistically compared. In addition, ductus venosus streaming patterns were examined.
Results: Despite the presence of intrathoracic liver herniation, predominant left heart hypoplasia, defined as a mitral valve Z-score < - 2 in combination with a tricuspid valve Z-score that was at least 2 Z larger than the mitral valve Z-score in an individual fetus, was observed in 11 of the 15 fetuses with left diaphragmatic hernia but in none of the 10 fetuses (p < 0.001) with right diaphragmatic hernia. Preferential streaming to the right heart was observed in 14 of the 15 fetuses with left hernia but in none of the 7 fetuses with right diaphragmatic hernia in whom this flow information was available (p < 0.0001).
Conclusion: Intrathoracic herniation of the liver ("liver-up") is associated with predominant left heart hypoplasia in left diaphragmatic hernia but not right fetal diaphragmatic hernia. Our observations indicate that this difference may result from different ductus venosus streaming sites in these conditions.
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