Intraoperative sodium range affects white matter microstructure in neonatal congenital heart disease

ObjectiveIntraoperative sodium changes and new postoperative white matter injury are prevalent in neonates with congenital heart disease (CHD) who undergo cardiopulmonary bypass surgery. Rapid sodium correction in hyponatremia is associated with white matter injury in adults. This study examined the potential effects of a rapid intraoperative sodium increase on white matter microstructure in neonates with CHD. Methods83 neonates with CHD underwent postoperative diffusion weighted magnetic resonance imaging within three weeks of cardiopulmonary bypass surgery as part of routine clinical practice. Mean diffusivity, radial diffusivity, and axial diffusivity were calculated using Diffusion Tensor Imaging. Voxel-wise associations within the core of white matter tracts were assessed using tract-based spatial statistics. Serum sodium measurements were extracted from clinical notes. Maximum intraoperative sodium range was defined as the difference between the minimum and maximum serum sodium observations during surgery. The rate of sodium change was calculated as this range divided by the time interval in hours. ResultsA larger maximum intraoperative sodium range was associated with lower axial diffusivity values in the right centrum semiovale, bilateral precentral white matter, right inferior longitudinal fasciculus, and right optic radiation (p<0.05, family wise error rate corrected). There were no other associations between diffusivities and sodium range or rate of change. ConclusionsA larger maximum intraoperative sodium range was associated with reduced axial diffusivity, possibly indicating axonal injury in neonates with CHD after cardiopulmonary bypass surgery. These findings underscore the importance of limiting perioperative osmotic stress to optimize white matter microstructural development. Central pictureWhite matter regions affected by intraoperative sodium range. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/25338157v1_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@d1692corg.highwire.dtl.DTLVardef@4fcb33org.highwire.dtl.DTLVardef@a590d1org.highwire.dtl.DTLVardef@1c68dc6_HPS_FORMAT_FIGEXP M_FIG C_FIG Central messageIntraoperative serum sodium changes are associated with white matter microstructural alterations in neonates with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass. Perspective statementRapid sodium changes are common in neonatal congenital heart disease surgery and are associated with white matter injury in other clinical populations. This study shows altered white matter microstructure in neonates with larger intraoperative sodium ranges, emphasizing the importance of limiting perioperative osmotic stress to optimise white matter microstructural development in this population.