Objective: The aim of this study was to determine whether the type of congenital heart disease (CHD) or heart function influence fetal cerebrovascular blood flow dynamics. Methods: Doppler flow velocimetry was performed in the umbilical artery (UA) and middle cerebral artery (MCA), and the ratio of the UA pulsatility index (PI) to the MCA PI (U/C PI) was determined in 45 fetuses with CHD at 20–40 weeks’ gestational age. The control group consisted of 275 healthy fetuses matched for gestational age. Individual PI measurements were converted into Z-scores for statistical analysis. Results: Fetuses with CHD (n = 45) had an increased UA PI (p = 0.001) and U/C PI (p < 0.001) when compared to controls. There was no significant difference in the MCA PI between fetuses with CHD (n = 45) and controls (n = 275), while fetuses with CHD complicated by congestive heart failure (CHF) (n = 10) had a decreased MCA PI (p < 0.001) compared to controls. Conclusions: The lower PIs observed in the MCA of fetuses with CHD complicated by CHF represents a marker of cerebral vasodilation that is due to cerebral hypoxemia and limiting perfusion. The heart function and type of CHD have an impact on fetal cerebrovascular blood flow distribution and this may contribute to the cause of abnormal neurologic development in these fetuses.

Fetal MCA Doppler assessment is affected by increased probe pressure but not by maternal VM. Thus, the application of the MCA Doppler sonography should be undertaken in the head of fetuses without any probe pressure and without maternal VM.