186: Evidence of fetal hypoxic brain injury in isolated congenital heart defect (CHD) as determined by newborn microcephaly


      Evidence suggests increased risk of fetal cerebral hypoxemia in CHD. Hypoxic brain injury could lead to poor brain growth and development. The risk of poor fetal brain growth as determined by newborn microcephaly was ascertained in isolated CHD.

      Study Design

      Head circumference (HC) was compared in 401 cases of isolated (non-chromosomal, non-syndromic) CHD cases vs matched controls. Microcephaly was defined as HC < 3rd percentile. Univariate and logistic regression analyses were performed to controlling for the effect of over 18 potential confounders including birthweight, type of heart lesion, and mixing (mixing of oxygenated and non-oxygenated blood) vs non-mixing lesion.


      Mean (SD) gestational age and birthweight were 38.1 (2.4) vs 38.5 (2.7) wks, p=ns, and 3018.8 (722.6) vs 3088 (639.7) gm, p< 0.01, in cases vs controls. The mean (SD) HC were 33.3 (2.4) cm and 33.6 (2.0) cm, p=0.04 in cases compared to controls. When only SGA cases from both groups were evaluated the HC difference was still significant (p=0.037). Comparison of controls, non-mixing and mixing CHD lesions showed a significant progressive reduction of HC mean (SD): 33.6 (2.0), 33.4 (2.5) and 33.2 (2.3) cm (p=0.02), respectively. This persisted after removal of SGA cases (p=0.037). Overall, the presence of an isolated fetal CHD significantly increased the risk of newborn microcephaly 56/401(14%) vs 34/401(8.4%), p=0.024. Anomalies that were significant independent predictors of microcephaly in CHD were tetralogy of Fallot, OR (95%, CI) 2.6 (1.1, 6.3), p< 0.04 and coarctation of the aorta, OR (95% CI) 2.8 (1.5, 5.1), p < 0.001. Corresponding rates of microcephaly were 23.5% and 21.7% respectively.


      High rates of microcephaly in categories of isolated CHD provide evidence of intrauterine brain injury consistent with chronic cerebral hypoxemia. Implications for prenatal management including parental counseling, need and timing of antenatal surveillance, and possibly earlier delivery in appropriate cases will need to be addressed.