Fetal brain imaging in isolated congenital heart defects - a systematic review and meta-analysis.

Congenital heart defects (CHDs) are associated with neurodevelopmental (ND) delay. This study aims to assess evidence for impaired prenatal brain development, in fetuses with CHD. A systematical search was performed, and 34 studies evaluating the fetal brain [magnetic resonance imaging (MRI) or ultrasound] in isolated CHD were included (1990-2015). Data regarding cerebral abnormalities, head circumference growth and middle cerebral artery flow were extracted. Prenatal MRI was studied in ten articles (445 fetuses), resulting in a pooled prevalence of 18% (95%CI -6%; 42%) for combined structural and acquired cerebral abnormalities. Prenatal head circumference was studied in 13 articles (753 fetuses), resulting in a pooled z-score of -0.51 (95%CI -0.84; -0.18). Doppler was studied in 21 articles (1412 fetuses), resulting in a lower middle cerebral artery pulsatility index (z-score -0.70 95%CI -0.99; -0.41) in left-sided CHD only. We conclude that prenatal MRI and ultrasound demonstrate brain abnormalities, delay in head growth and brainsparing in subgroups of CHD. However, large MRI studies are scarce, and ultrasound data are biased towards severe and left-sided CHD. Long-term follow-up studies correlating prenatal findings with postnatal ND outcome are limited, and data are lacking to support counseling families regarding ND outcome based on prenatal findings suggestive of altered brain development.