Neonates with complex congenital heart disease (CHD), in particular newborns with hypoplastic left heart syndrome (HLHS) or transposition of the great arteries (TGA), may show brain pathologies and altered brain growth after birth. Our prospective study investigates brain volumes and immature brain structures in these patient groups compared to healthy controls.

Neonatal cerebral magnetic resonance imaging (MRI) scans were analysed by semi-automated segmentation (dHCP pipeline) in 51 children: 31 HLHS/hypoplastic left heart complex (HLHC)/UVH (61%) at stage I, in 18 neonates with TGA (35%) and in 2 with aortic arch obstruction and biventricular physiology (4%) at a mean GA 41.2 weeks, and in 209 controls at a mean GA 41.6 at time of the MRI. Newborns born premature were excluded. Brain volume comparisons used mixed models for imaging techniques and linear regression for CHD-control differences.

Cerebral MRI was abnormal in 29 patients (57%), with multiple lesions in some patients: including liquor space enlargements (20%), small grey (20%) and white matter injuries (12%), stroke (8%), subdural haemorrhage (22%), and sinus venous thrombosis (8%). Sixty-nine percent of CHD neonates showed signs of brain immaturity in relation to GA. Intracranial volumes were reduced, while cerebrospinal fluid (CSF) volumes were enlarged compared to controls.

Neonates with complex CHD show reduced cerebral growth, higher risk for brain injuries, and impaired brain maturation, even before first surgery. This might constitute a higher perioperative risk in these patient groups than for normal developed brains. Identification of distinct patterns of brain volume loss might enable risk stratification for subsequent neuro-developmental impairment.