Ascending Aorta Size at Birth Predicts White Matter Microstructure in Adolescents Who Underwent Fontan Palliation

Background In neonates with single ventricle, smaller ascending aorta diameter is associated with cerebral white matter ( WM ) microstructural abnormalities. We sought to determine whether this association persists into adolescence. Methods and Results Ascending aorta Z scores were obtained from first postnatal echocardiogram. Brain magnetic resonance imaging with diffusion tensor imaging was acquired in adolescence and used to obtain fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity in 33 WM tract regions of interest. Partial Pearson correlation coefficients were evaluated for associations between ascending aorta Z scores and WM microstructure measures, adjusting for sex, age at magnetic resonance imaging, scanner field strength, and Norwood status. Among 42 single ventricle patients aged 10 to 19 years, 31 had undergone the Norwood procedure as neonates. Lower ascending aorta Z scores were associated with lower fractional anisotropy in bilateral pontine crossing tracts ( P=0.02), inferior fronto-occipital fasciculus ( P=0.02), and inferior longitudinal fasciculus ( P=0.01); left cingulum-cingulate bundle ( P=0.01), superior longitudinal fasciculus ( P=0.04), and superior longitudinal fasciculus-temporal component ( P=0.01); and right cingulum-hippocampal bundle (P=0.009) and inferior cerebellar peduncle ( P=0.01). Lower ascending aorta Z scores were associated with higher radial diffusivity and mean diffusivity in a similar regional pattern but not with axial diffusivity. Conclusions In adolescents with single ventricle, smaller aorta diameter at birth is associated with abnormalities of WM microstructure in a subset of WM tracts, mostly those located in deeper brain regions. Our findings suggest that despite multiple intervening medical or surgical procedures, prenatal cerebral blood flow may have a lasting influence on WM microstructure in single-ventricle patients.