P2.015: Placental pathology in congenital heart disease alters the relationship between placental oxygen metabolism and fetal vascular Dopplers

Background: Fetuses with congenital heart disease (CHD) have higher rates of placental pathologic abnormalities, particularly abnormal vascular development. In utero, fetal circulatory disturbances are measured using extra-cardiac Doppler ultrasound (ECD-US), including the umbilical artery (UmbA), middle cerebral artery (MCA) and ductus venosus (DV). Placental magnetic resonance imaging (MRI) is increasingly used to directly investigate placental oxygen metabolism in fetuses with and without CHD. However, the relationship between ECD-US and placental MRI measures of oxygen metabolism are yet unclear. Furthermore, in fetuses with CHD, the impact of placental pathology on these measures individually and on their interrelationship is also unknown.

Methods: Pregnant mothers of fetuses with critical CHD were prospectively enrolled and underwent fetal ECD-US and feto-placental MRI on the same day. US evaluated ECD, with calculations of pulsatility index Z-scores (PI-Z) as a marker for vessel resistance for gestational age. Placental spatiotemporal variance and vascular reactivity were calculated, as previously published (Rajagopalan, et al. 2022). The presence of placental pathology, as defined by Amsterdam criteria, were binarized into present or absent. A composite “Any Pathology” variable was created to capture pathologically normal versus abnormal placentas. The relationships between placental pathology, ED-US and MRI were evaluated with robust linear regression.

Results: Forty-seven fetuses underwent feto-placental MRI, at a mean of 33.6 (±3.0) weeks GA. Thirty-seven placentas were analyzed, 59.5% of which had a pathologic finding. Placentas with any pathology had significantly lower temporal variance (0.004 ± 0.002 vs. -0.007 ± 0.003, p=0.03); placentas with avascular villi had significantly lower spatial variance (0.2 ± 0.2 vs. -0.9 ± 0.5, p=0.05). Abnormal UmbA PI-Z was associated with greater temporal variance (-0.001 ± 0.001 vs. 0.006 ± 0.002, p=0.01). The positive association between MCA end-diastolic velocity (EDV) and spatial variance is weakened in the presence of any pathology (1.46 ± 0.47 vs. 0.12 ± 0.05, p=0.01). Fetuses with lower DV A-wave velocity had greater spatial variance though spatial variance was lower in the presence of acute chorioamnionitis (0.513 ± 0.063 vs. -0.005 ± 0.003, p=0.02).

Conclusion: The presence of placental pathology in fetuses with CHD alters placental oxygen metabolism and function, as measured by placental MRI and ECD-US.