Fetal cerebrovascular response to maternal hyperoxia testing may help predict neurodevelopmental outcomes
1. In this prospective cohort of fetuses with congenital heart disease (CHD), specifically hypoplastic left heart syndrome (HLHS), a lack of cerebrovascular response to maternal hyperoxia (MH) was associated with smaller brain volume before birth and higher risk of white matter injury after birth.
Evidence Rating Level: 1 (Excellent)
Neurodevelopmental complications are the most frequent coexisting condition in children with significant congenital heart disease (CHD), even with no genetic or other structural abnormalities. Previous studies have suggested that these issues often originate prenatally, since fetuses with CHD show signs of abnormal brain development, including smaller brain volumes and immature brain structure and metabolism. Decreased brain volume is associated with developmental outcomes in infancy and may be a contributor to white matter injury (WMI) after birth, affecting motor outcomes. Predicting neurodevelopmental outcomes before birth remains difficult, limiting the ability to provide targeted counselling and care. One tool that has not been fully explored is maternal hyperoxia (MH) testing, involving administering oxygen to pregnant individuals to affect fetal blood flow. The goal of this study was to investigate whether an abnormal cerebral vascular response to MH testing is associated with poor brain growth and a higher risk of postnatal WMI in fetuses with CHD. The study enrolled 55 participants who underwent a fetal echocardiogram and brain MRI. After adjustments were made, there was no statistically significant association between change in middle cerebral artery pulsatility index (MCA PI) with MH and fetal total brain volume (TBV) (coefficient, 0.21 [95% CI, -0.18 to 0.61]; P=0.28). In fetuses with hypoplastic left heart syndrome (HLHS), those who responded to the oxygen test had, on average, 17.8 mL more TBV than those who had no response, at each week of pregnancy (95% CI, 3.3 to 32.3; P=0.02). This trend was not noted in the d-transposition of the great arteries (D-TGA) group (coefficient, -4.67 [95% CI, -27.0 to 17.61]; P=0.68). Fetuses who developed WMI before surgery showed a significantly lower change in the MCA PI during the oxygen test (mean percentage change, -11.5 [95% CI, -20.5 to -2.6]) compared to those without MI, who showed an average increase of 7.1% (95% CI, -1.9 to 16.2; P=0.04). These results highlight the efficacy and utility of MH testing to help identify fetuses at highest risk for poor neurodevelopmental outcomes.
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