Abstract 4551: Third-Trimester Volumetric Brain Growth is Impaired in Fetuses with Congenital Heart Disease
A significant proportion of newborns with CHD show evidence of impaired brain development at birth. Identifying the onset of brain growth impairment may be critical for future management of fetal CHD. We prospectively performed advanced 3D-MRI to compare volumetric brain growth in healthy control fetuses and fetuses diagnosed by echo with CHD. We excluded cases with genetic or dysgenetic brain lesions. Quantitative measures of fetal intracranial (ICV), total brain volume (TBV), and cerebrospinal fluid (CSF) were carried out. Aortic and pulmonary output, and umbilical and cerebral flow were measured by echo in fetuses with CHD. We studied 105 fetuses (median GA 30 wks, range 25–37): 55 normal, 50 with CHD. At 26 wks TBV did not differ between groups, but TBV decreased progressively over the third trimester in CHD fetuses relative to controls adjusting for GA and weight (p<0.001, Figure⇓). In multivariable analysis adjusting for GA and weight, diagnosis was an independent predictor of TBV (p<0.001); the lowest in HLHS (n=19), followed by TGA (13), pulmonary atresia (7), and other CHD (11). Among fetuses with CHD, lower aortic outflow as a percentage of combined ventricular output was independently associated with lower TBV (p=0.005). The CSF/ICV ratio, which normally decreases from ~0.5 at 26 wks to ~0.1 at term, was progressively higher in CHD fetuses through the third trimester (p=0.001). In the fetus with CHD, brain growth is normal through 26 weeks of gestation. However during the third trimester, normally a period of rapid brain growth, brain growth decreases progressively in CHD fetuses, particularly those with abnormal systemic ventricular outflow.