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Background: Brain injury is a serious and common complication of critical congenital heart disease (CHD). Impaired autonomic development (assessed by heart rate variability (HRV)) is associated with brain injury in other high-risk neonatal populations., Objective: To determine whether impaired early neonatal HRV is associated with pre-operative brain injury in CHD., Methods: In infants with critical CHD, we evaluated HRV during the first 24 h of cardiac ICU (CICU) admission using time-domain (RMS 1, RMS 2, and alpha 1) and frequency-domain metrics (LF, nLF, HF, nHF). Pre-operative brain magnetic resonance imaging (MRI) was scored for injury using an established system. Spearman's correlation coefficient was used to determine the association between HRV and pre-operative brain injury., Results: We enrolled 34 infants with median birth gestational age of 38.8 weeks (IQR 38.1-39.1). Median postnatal age at pre-operative brain MRI was 2 days (IQR 1-3 days). Thirteen infants had MRI evidence of brain injury. RMS 1 and RMS 2 were inversely correlated with pre-operative brain injury., Conclusions: Time-domain metrics of autonomic function measured within the first 24 h of admission to the CICU are associated with pre-operative brain injury, and may perform better than frequency-domain metrics under non-stationary conditions such as critical illness., Impact: Autonomic dysfunction, measured by heart rate variability (HRV), in early transition is associated with pre-operative brain injury in neonates with critical congenital heart disease. These data extend our earlier findings by providing further evidence for (i) autonomic dysfunction in infants with CHD, and (ii) an association between autonomic dysfunction and brain injury in critically ill neonates. These data support the notion that further investigation of HRV as a biomarker for brain injury risk is warranted in infants with critical CHD., (© 2021. The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc.)

Background: The objective was to determine the association between perioperative risk factors and brain imaging abnormalities on neurologic outcome in neonates with hypoplastic left heart syndrome (HLHS) or d-Transposition of the great arteries (d-TGA) who underwent cardiac surgery including cardiopulmonary bypass., Methods: A retrospective analysis of neonates with HLHS or d-TGA undergoing cardiac surgery including cardiopulmonary bypass between 2009 and 2017 was performed. Perioperative risk factors and Andropoulos' Brain Injury Scores from pre- and postoperative brain magnetic resonant images (MRI) were correlated to outcome assessments on patients between 5 and 23 months of age. Neurologic outcome was measured using the Pediatric Stroke Outcome Measure (PSOM) and Pediatric Version of the Glasgow Outcome Scale-Extended (GOS-E)., Results: Fifty-three neonates met our enrollment criteria (24 HLHS, 29 d-TGA). Mechanical ventilation > 12 days and DHCA > 40 min were associated with worse outcome. MRI measures of brain injuries were not associated with worse outcome by PSOM or GOS-E., Conclusion: For HLHS and d-TGA patients, duration of mechanical ventilation and DHCA are associated with adverse neurologic outcome. Neonatal brain MRI commonly demonstrates acquired brain injuries, but the clinical impact of these abnormalities are not often seen before 2 years of age., Impact: Acquired brain injury is common in high-risk neonates with CHD but poor neurological outcome was not predicted by severity of injury or lesion subtype. Longer stay in ICU is associated with postoperative brain injuries on MRI. Total duration of ventilation > 12 days is predictive of adverse neurological outcome scores. DHCA > 40 min is associated with adverse neurological outcome scores. Neurological outcome before 2 years of age is more affected by the clinical course than by cardiac diagnosis.

Gamma-aminobutyric acid (GABA) and glutamate are principal neurotransmitters essential for late gestational brain development and may play an important role in prematurity-related brain injury. In vivo investigation of GABA in the preterm infant with standard proton magnetic resonance spectroscopy ( 1 H-MRS) has been limited due to its low concentrations in the developing brain, and overlap in the spectrum by other dominant metabolites. We describe early postnatal profiles of in vivo GABA and glutamate concentrations in the developing preterm brain measured by using the J-difference editing technique, Mescher-Garwood point resolved spectroscopy. We prospectively enrolled very preterm infants born ≤32 weeks gestational age and non-sedated 1 H-MRS (echo time 68 ms, relaxation time 2000 ms, 256 signal averages) was acquired on a 3 Tesla magnetic resonance imaging scanner from a right frontal lobe voxel. Concentrations of GABA + (with macromolecules) was measured from the J-difference spectra; whereas glutamate and composite glutamate + glutamine (Glx) were measured from the unedited (OFF) spectra and reported in institutional units. We acquired 42 reliable spectra from 38 preterm infants without structural brain injury [median gestational age at birth of 28.0 (IQR 26.0, 28.9) weeks; 19 males (50%)] at a median postmenstrual age of 38.4 (range 33.4 to 46.4) weeks. With advancing post-menstrual age, the concentrations of glutamate OFF increased significantly, adjusted for co-variates (generalized estimating equation β = 0.22, p = 0.02). Advancing postnatal weeks of life at the time of imaging positively correlated with GABA + (β = 0.06, p = 0.02), glutamate OFF (β = 0.11, p = 0.02) and Glx OFF (β = 0.12, p = 0.04). Male infants had higher GABA + (1.66 ± 0.07 vs. 1.33 ± 0.11, p = 0.01) concentrations compared with female infants. For the first time, we report the early ex-utero developmental profile of in vivo GABA and glutamate stratified by age and sex in the developing brain of very preterm infants. This data may provide novel insights into the pathophysiology of neurodevelopmental disabilities reported in preterm infants even in the absence of structural brain injury.

Objective: To determine whether ventilator-related fluctuations in cerebral blood volume (CBV) are associated with cerebral pressure passivity., Study Design: In a prospective study of newborns undergoing positive-pressure ventilation, we calculated coherence between continuous mean arterial pressure (MAP) and cerebral near-infrared spectroscopy hemoglobin difference (HbD). Significant HbD-MAP coherence indicated cerebral pressure passivity. CBV changes were measured as the spectral power of total hemoglobin (S HbT ) at the ventilator frequency. A regression model tested whether S HbT predicts cerebral pressure passivity and/or death/brain injury, controlling for birth gestational age and other factors., Results: We studied 68 subjects with prematurity (n = 19), congenital heart disease (n = 11), and hypoxic-ischemic encephalopathy (n = 38). S HbT , sedative use, and pCO 2 were positively associated, and circulating hemoglobin negatively associated, with cerebral pressure passivity (p < 0.001), which was positively associated with brain injury (p < 0.001)., Conclusion: In sick newborns, ventilator-related CBV fluctuations may predispose to cerebral pressure passivity, which may predispose to an adverse neonatal outcome.

Congenital heart disease (CHD) is an independent risk factor for brain injury, including stroke, and poor neurodevelopmental outcomes, and placental abnormalities may represent an additional risk factor for brain injury in neonates. The incidence and scope of placental pathology and relationship to fetal brain abnormalities in pregnancies complicated by fetal CHD has not been explored to our knowledge. In order to determine the prevalence of placental pathology findings and whether placental findings are associated with postnatal brain injury in pregnancies complicated by fetal CHD, we reviewed placental pathology reports for 51 pregnancies complicated by CHD and scored available postnatal, pre-operative brain MRI for brain pathology. Overall, 57% of CHD infants had abnormal placental pathology. Pregnancies complicated by CHD with aortic obstruction (AO) were significantly more likely than those with no obstruction to have abnormal placental pathology (79% vs. 44%). There was a trend toward more severe brain lesions amongst patients with brain lesions and placental abnormality (55% moderate/severe) compared to those without placental abnormality (11% moderate/severe). These data suggest that placental abnormalities are common in CHD and may have a compounding effect on brain lesions in this high-risk population.

Advanced neuroimaging techniques have improved our understanding of microstructural changes in the preterm supratentorial brain as well as the cerebellum and its association with impaired neurodevelopmental outcomes. However, the metabolic interrogation of the developing cerebellum during the early postnatal period after preterm birth remains largely unknown. Our study investigates the relationship between cerebellar neurometabolites measured by proton magnetic spectroscopy ( 1 H-MRS) in preterm infants with advancing post-menstrual age (PMA) and brain injury during ex-utero third trimester prior to term equivalent age (TEA). We prospectively enrolled and acquired high quality 1 H-MRS at median 33.0 (IQR 31.6-35.2) weeks PMA from a voxel placed in the cerebellum of 53 premature infants born at a median gestational age of 27.0 (IQR 25.0-29.0) weeks. 1 H-MRS data were processed using LCModel software to calculate absolute metabolite concentrations of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr). We noted positive correlations of cerebellar concentrations of NAA, Cho and Cr (Spearman correlations of 0.59, 0.64 and 0.52, respectively, p value < 0.0001) and negative correlation of Cho/Cr ratio (R -0.5, p value 0.0002) with advancing PMA. Moderate-to-severe cerebellar injury was noted on conventional magnetic resonance imaging (MRI) in 14 (26.4%) of the infants and were noted to have lower cerebellar NAA, Cho and Cr concentrations compared with those without injury (p value < 0.001). Several clinical complications of prematurity including necrotizing enterocolitis, systemic infections and bronchopulmonary dysplasia were associated with altered metabolite concentrations in the developing cerebellum. We report for the first time that ex-utero third trimester cerebellar metabolite concentrations are decreased in very preterm infants with moderate-to-severe structural cerebellar injury. We report increasing temporal trends of metabolite concentrations in the cerebellum with advancing PMA, which was impaired in infants with brain injury on MRI and may have early diagnostic and prognostic value in predicting neurodevelopmental outcomes in very preterm infants.

This study aims to compare the cerebellar biochemical profiles in preterm (PT) infants evaluated at term equivalent age (TEA) and healthy full-term newborns using proton magnetic resonance spectroscopy ( 1 H-MRS). We explore the associations between altered cerebellar metabolite profiles and brain injury topography, severity of injury, and prematurity-related clinical complications. We prospectively collected high quality 1 H-MRS in 59 premature infants born ≤32 weeks and 61 healthy full term controls. 1 H-MRS data were processed using LCModel software to calculate absolute metabolite concentration for N-acetyl-aspartate (NAA), choline (Cho) and creatine (Cr). PT infants had significantly lower cerebellar NAA (p < 0.025) and higher Cho (p < 0.001) at TEA when compared to healthy controls. Creatine was not different between the two groups. The presence of cerebellar injury was consistently associated with reduced concentrations for NAA, Cho, and Cr. Postnatal infection was negatively associated with NAA and Cr (p < 005), while cerebral cortical brain injury severity was inversely associated with both Cho and Cr (p < 0.01). We report for the first time that premature birth is associated with altered cerebellar metabolite profiles when compared to term born controls. Infection, cerebellar injury and supratentorial injury are important risk factors for impaired preterm cerebellar biochemistry.

Objective: To evaluate the clinical impact of routine term-equivalent magnetic resonance imaging (TE-MRI) for extremely low-birth-weight infants at a regional neonatal intensive care unit., Study Design: This is a single-center retrospective study evaluating preterm survivors who underwent TE-MRI. MRI abnormalities were compared between infants with and without cranial ultrasonography (CUS) abnormalities. Cost analysis comparing imaging modalities was also performed., Results: TE-MRI use increased from 17% in 2006 to 76% in 2010. MRI detected new findings in nearly half of infants, whether or not they had known ultrasound abnormalities. MRI detected more cerebellar (18% vs 6%, P=0.04) and moderate white matter injury (12% vs 7%, P<0.001), and altered simulated neurological prognosis across developmental domains. The cost of TE-MRI was $1600, which was comparable to serial CUSs., Conclusion: TE-MRI detects new abnormalities and impacts developmental prognosis in the extremely low birth weight, which supports its use despite the added financial cost.