Investigating altered brain development in infants with congenital heart disease using tensor-based morphometry

Total and Regional Brain Volumes in Fetuses With Congenital Heart Disease

BACKGROUND

Congenital heart disease (CHD) is common and is associated with impaired early brain development and neurodevelopmental outcomes, yet the exact mechanisms underlying these associations are unclear.

PURPOSE

To utilize MRI data from a cohort of fetuses with CHD as well as typically developing fetuses to test the hypothesis that expected cerebral substrate delivery is associated with total and regional fetal brain volumes.

STUDY TYPE

Retrospective case-control study.

POPULATION

Three hundred eighty fetuses (188 male), comprising 45 healthy controls and 335 with isolated CHD, scanned between 29 and 37 weeks gestation. Fetuses with CHD were assigned into one of four groups based on expected cerebral substrate delivery.

FIELD STRENGTH/SEQUENCE

T2-weighted single-shot fast-spin-echo sequences and a balanced steady-state free precession gradient echo sequence were obtained on a 1.5 T scanner.

ASSESSMENT

Images were motion-corrected and reconstructed using an automated slice-to-volume registration reconstruction technique, before undergoing segmentation using an automated pipeline and convolutional neural network that had undergone semi-supervised training. Differences in total, regional brain (cortical gray matter, white matter, deep gray matter, cerebellum, and brainstem) and brain:body volumes were compared between groups.

STATISTICAL TESTS

ANOVA was used to test for differences in brain volumes between groups, after accounting for sex and gestational age at scan. PFDR-values <0.05 were considered statistically significant.

RESULTS

Total and regional brain volumes were smaller in fetuses where cerebral substrate delivery is reduced. No significant differences were observed in total or regional brain volumes between control fetuses and fetuses with CHD but normal cerebral substrate delivery (all PFDR > 0.12). Severely reduced cerebral substrate delivery is associated with lower brain:body volume ratios.

DATA CONCLUSION

Total and regional brain volumes are smaller in fetuses with CHD where there is a reduction in cerebral substrate delivery, but not in those where cerebral substrate delivery is expected to be normal.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 3.

Children with Congenital Heart Diseases Exhibit Altered Deep Gray Matter Structures

BACKGROUND AND OBJECTIVES

Children with congenital heart diseases (CHDs) have an increased risk of developing neurologic deficits, even in the absence of apparent brain pathology. The aim of this work was to compare quantitative macro- and microstructural properties of subcortical gray matter structures of pediatric CHD patients with normal appearing brain magnetic resonance imaging to healthy controls.

METHODS

We retrospectively reviewed children with coarctation of the aorta (COA) and hypoplastic left heart syndrome (HLHS) admitted to our hospital. We identified 24 pediatric CHD patients (17 COA, 7 HLHS) with normal-appearing brain MRI. Using an atlas-based approach, the volume and apparent diffusion coefficient (ADC) were determined for the thalamus, caudate, putamen, pallidum, hippocampus, amygdala, nucleus accumbens, cerebral white matter, cerebral cortex, and brainstem. Multivariate statistics were used to compare the extracted values to reference values from 100 typically developing children without any known cardiac or neurological diseases.

RESULTS

Multivariate analysis of covariance using the regional ADC and volume values as dependent variables and age and sex as co-variates revealed a significant difference between pediatric CHD patients and healthy controls (p < 0.001). Post-hoc comparisons demonstrated significantly reduced brain volumes in most subcortical brain regions investigated and elevated ADC values in the thalamus for children with CHD. No significant differences were found comparing children with COA and HLHS.

CONCLUSIONS

Despite normal appearing brain MRI, children with CHD exhibit wide-spread macro-structural and regional micro-structural differences of subcortical brain structures compared to healthy controls, which could negatively impact neurodevelopment, leading to neurological deficits in childhood and beyond.

Effects of hemodynamic alterations and oxygen saturation on cerebral perfusion in congenital heart disease

BACKGROUND

Patients with severe congenital heart disease (CHD) are at risk for neurodevelopmental impairment. An abnormal cerebral blood supply caused by the altered cardiac physiology may limit optimal brain development. The aim of this study was to evaluate the effect of a systemic-to-pulmonary shunt, aortic arch obstruction and arterial oxygen saturation on cerebral perfusion in patients with severe CHD.

METHODS

Patients with severe CHD requiring cardiac surgery within the first six weeks of life, who underwent pre- and/or postoperative brain magnetic resonance imaging (MRI), and healthy controls with one postnatal scan were included. Cerebral perfusion in deep and cortical gray matter was assessed by pseudocontinuous arterial spin labeling MRI.

RESULTS

We included 59 CHD and 23 healthy control scans. The presence of a systemic-to-pulmonary shunt was associated with decreased perfusion in cortical (p = 0.003), but not in deep gray matter (p = 0.031). No evidence for an effect of aortic arch obstruction and arterial oxygen saturation on cerebral perfusion was found. After adjusting for hemodynamic and oxygen saturation parameters, deep (p = 0.018) and cortical (p = 0.012) gray matter perfusion was increased in patients with CHD compared to controls.

CONCLUSION

We detected regional differences in compensation to the cerebral steal effect in patients with severe CHD.

IMPACT

Patients with severe congenital heart disease (CHD) have altered postnatal brain hemodynamics. A systemic-to-pulmonary shunt was associated with decreased perfusion in cortical gray matter but preserved perfusion in deep gray matter, pointing towards regional differences in compensation to the cerebral steal effect. No effects of aortic arch obstruction and arterial oxygenation on cerebral perfusion were seen. Cerebral perfusion was increased in patients with CHD compared to healthy controls after adjusting for hemodynamic alterations and oxygen saturation. To improve neuroprotection and neurodevelopmental outcomes, it is important to increase our understanding of the factors influencing cerebral perfusion in neonates with severe CHD.

Characterization of dynamic patterns of human fetal to neonatal brain asymmetry with deformation-based morphometry

Introduction

Despite established knowledge on the morphological and functional asymmetries in the human brain, the understanding of how brain asymmetry patterns change during late fetal to neonatal life remains incomplete. The goal of this study was to characterize the dynamic patterns of inter-hemispheric brain asymmetry over this critically important developmental stage using longitudinally acquired MRI scans.

Methods

Super-resolution reconstructed T2-weighted MRI of 20 neurotypically developing participants were used, and for each participant fetal and neonatal MRI was acquired. To quantify brain morphological changes, deformation-based morphometry (DBM) on the longitudinal MRI scans was utilized. Two registration frameworks were evaluated and used in our study: (A) fetal to neonatal image registration and (B) registration through a mid-time template. Developmental changes of cerebral asymmetry were characterized as (A) the inter-hemispheric differences of the Jacobian determinant (JD) of fetal to neonatal morphometry change and the (B) time-dependent change of the JD capturing left-right differences at fetal or neonatal time points. Left-right and fetal-neonatal differences were statistically tested using multivariate linear models, corrected for participants' age and sex and using threshold-free cluster enhancement.

Results

Fetal to neonatal morphometry changes demonstrated asymmetry in the temporal pole, and left-right asymmetry differences between fetal and neonatal timepoints revealed temporal changes in the temporal pole, likely to go from right dominant in fetal to a bilateral morphology in neonatal timepoint. Furthermore, the analysis revealed right-dominant subcortical gray matter in neonates and three clusters of increased JD values in the left hemisphere from fetal to neonatal timepoints.

Discussion

While these findings provide evidence that morphological asymmetry gradually emerges during development, discrepancies between registration frameworks require careful considerations when using DBM for longitudinal data of early brain development.

Functional brain connectivity after corrective cardiac surgery for critical congenital heart disease: a preliminary near-infrared spectroscopy (NIRS) report

Patients with congenital heart disease (CHD) requiring cardiac surgery in infancy are at high risk for neurodevelopmental impairments. Neonatal imaging studies have reported disruptions of brain functional organization before surgery. Yet, the extent to which functional network alterations are present after cardiac repair remains unexplored. This preliminary study aimed at investigating cortical functional connectivity in 4-month-old infants with repaired CHD, using resting-state functional near-infrared spectroscopy (fNIRS). After fNIRS signal frequency decomposition, we compared values of magnitude-squared coherence as a measure of connectivity strength, between 21 infants with corrected CHD and 31 healthy controls. We identified a subset of connections with differences between groups at an uncorrected statistical level of p < .05 while controlling for sex and maternal socioeconomic status, with most of these connections showing reduced connectivity in infants with CHD. Although none of these differences reach statistical significance after FDR correction, likely due to the small sample size, moderate to large effect sizes were found for group-differences. If replicated, these results would therefore suggest preliminary evidence that alterations of brain functional connectivity are present in the months after cardiac surgery. Additional studies involving larger sample size are needed to replicate our data, and comparisons between pre- and postoperative findings would allow to further delineate alterations of functional brain connectivity in this population.

Postnatal cerebral hemodynamics in infants with severe congenital heart disease: a scoping review

Patients with severe congenital heart disease (CHD) are at risk for impaired neurodevelopment. Cerebral blood supply may be diminished by congenital anomalies of cardiovascular anatomy and myocardial function. The aim of this scoping review was to summarize the current knowledge on cerebral hemodynamics in infants with severe CHD. A scoping review was performed. Five databases were searched for articles published from 01/1990 to 02/2022 containing information on cerebral hemodynamics assessed by neuroimaging methods in patients with severe CHD within their first year of life. A total of 1488 publications were identified, of which 26 were included. Half of the studies used Doppler ultrasound, and half used magnetic resonance imaging techniques. Studies focused on preoperative findings of cerebral hemodynamics, effects of surgical and conservative interventions, as well as on associations between cerebral hemodynamics and brain morphology or neurodevelopment. Cerebral perfusion was most severely affected in patients with single ventricle and other cyanotic disease. Neuroimaging methods provide a large variety of information on cerebral hemodynamics. Nevertheless, small and heterogeneous cohorts complicate this field of research. Further studies are needed to improve our understanding of the link between CHD and altered cerebral hemodynamics to optimize neuroprotection strategies. IMPACT: Postnatal cerebral hemodynamics are altered in infants with congenital heart disease (CHD) as compared to healthy controls, especially in most severe types such as single ventricle or other cyanotic CHD. Associations of these alterations with brain volume and maturation reveal their clinical relevance. Research in this area is limited due to the rarity and heterogeneity of diagnoses. Furthermore, longitudinal studies have rarely been conducted. Further effort is needed to better understand the deviation from physiological cerebral perfusion and its consequences in patients with CHD to optimize neuroprotection strategies.

Individual Assessment of Perioperative Brain Growth Trajectories in Infants With Congenital Heart Disease: Correlation With Clinical and Surgical Risk Factors

Background Infants with congenital heart disease (CHD) are at risk of neurodevelopmental impairments, which may be associated with impaired brain growth. We characterized how perioperative brain growth in infants with CHD deviates from typical trajectories and assessed the relationship between individualized perioperative brain growth and clinical risk factors. Methods and Results A total of 36 infants with CHD underwent preoperative and postoperative brain magnetic resonance imaging. Regional brain volumes were extracted. Normative volumetric development curves were generated using data from 219 healthy infants. Z-scores, representing the degree of positive or negative deviation from the normative mean for age and sex, were calculated for regional brain volumes from each infant with CHD before and after surgery. The degree of Z-score change was correlated with clinical risk factors. Perioperative growth was impaired across the brain, and it was associated with longer postoperative intensive care stay (false discovery rate P<0.05). Higher preoperative creatinine levels were associated with impaired brainstem, caudate nuclei, and right thalamus growth (all false discovery rate P=0.033). Older postnatal age at surgery was associated with impaired brainstem and right lentiform growth (both false discovery rate P=0.042). Longer cardiopulmonary bypass duration was associated with impaired brainstem and right caudate growth (false discovery rate P<0.027). Conclusions Infants with CHD can have impaired brain growth in the immediate postoperative period, the degree of which associates with postoperative intensive care duration. Brainstem growth appears particularly vulnerable to perioperative clinical course, whereas impaired deep gray matter growth was associated with multiple clinical risk factors, possibly reflecting vulnerability of these regions to short- and long-term hypoxic injury.

Association of Preterm Birth and Socioeconomic Status With Neonatal Brain Structure

Importance

Preterm birth and socioeconomic status (SES) are associated with brain structure in childhood, but the relative contributions of each during the neonatal period are unknown.

Objective

To investigate associations of birth gestational age (GA) and SES with neonatal brain morphology by testing 3 hypotheses: GA and SES are associated with brain morphology; associations between SES and brain morphology vary with GA; and associations between SES and brain structure and morphology depend on how SES is operationalized.

Design, Setting, and Participants

This cohort study recruited participants from November 2016 to September 2021 at a single center in the United Kingdom. Participants were 170 extremely and very preterm infants and 91 full-term or near-term infants. Exclusion criteria were major congenital malformation, chromosomal abnormality, congenital infection, cystic periventricular leukomalacia, hemorrhagic parenchymal infarction, and posthemorrhagic ventricular dilatation.

Exposures

Birth GA and SES, operationalized at the neighborhood level (using the Scottish Index of Multiple Deprivation), the family level (using parental education and occupation), and subjectively (World Health Organization Quality of Life measure).

Main Outcomes and Measures

Brain volume (85 parcels) and 5 whole-brain cortical morphology measures (gyrification index, thickness, sulcal depth, curvature, surface area) at term-equivalent age (median [range] age, 40 weeks, 5 days [36 weeks, 2 days to 45 weeks, 6 days] and 42 weeks [38 weeks, 2 days to 46 weeks, 1 day] for preterm and full-term infants, respectively).

Results

Participants were 170 extremely and very preterm infants (95 [55.9%] male; 4 of 166 [2.4%] Asian, 145 of 166 [87.3%] White) and 91 full-term or near-term infants (50 [54.9%] male; 3 of 86 [3.5%] Asian, 78 of 86 [90.7%] White infants) with median (range) birth GAs of 30 weeks, 0 days (22 weeks, 1 day, to 32 weeks, 6 days) and 39 weeks, 4 days (36 weeks, 3 days, to 42 weeks, 1 day), respectively. In fully adjusted models, birth GA was associated with a higher proportion of brain volumes (27 of 85 parcels [31.8%]; β range, -0.20 to 0.24) than neighborhood-level SES (1 of 85 parcels [1.2%]; β = 0.17 [95% CI, -0.16 to 0.50]) or family-level SES (maternal education: 4 of 85 parcels [4.7%]; β range, 0.09 to 0.15; maternal occupation: 1 of 85 parcels [1.2%]; β = 0.06 [95% CI, 0.02 to 0.11] respectively). There were interactions between GA and both family-level and subjective SES measures on regional brain volumes. Birth GA was associated with cortical surface area (β = 0.10 [95% CI, 0.02 to 0.18]) and gyrification index (β = 0.16 [95% CI, 0.07 to 0.25]); no SES measure was associated with cortical measures.

Conclusions and Relevance

In this cohort study of UK infants, birth GA and SES were associated with neonatal brain morphology, but low GA had more widely distributed associations with neonatal brain structure than SES. Further work is warranted to elucidate the mechanisms underlying the association of both GA and SES with early brain development.

Evaluation of Intracranial Structures of Fetuses With Congenital Heart Defects

OBJECTIVES

We classified congenital heart defects (CHDs) according to cerebral blood flow oxygenation and aimed to evaluate the effect on the size of brain structures in these fetuses.

METHODS

The study which was designed retrospectively, included 28 patients with fetal CHDs and 76 patients without fetal anomalies.

RESULTS

The width and length of the cavum septum pellucidum significantly increased in the CHD group (P = .002, P = .004). The biparietal diameter and z scores were significantly lower in the single ventricle (SV) (P = .006, P = .019), and the head circumference (HC) and z scores were significantly lower in the transposition of great arteries (TGA) (P = .013, P = .038). The transverse cerebellar diameter, the cerebellar HC and the cerebellar hemisphere area values were lower in the SV (P = .005, P = .017, P = .044).

CONCLUSIONS

Brain structure changes are more pronounced in groups with low cerebral oxygenation, especially in the SV and the TGA.

Structural Racism, Social Determinants of Health, and Provider Bias: Impact on Brain Development in Critical Congenital Heart Disease

Critical congenital heart disease (cCHD) has neurodevelopmental sequelae that can carry into adulthood, which may be due to aberrant brain development or brain injury in the prenatal and perinatal/neonatal periods and beyond. Health disparities based on the intersection of sex, geography, race, and ethnicity have been identified for poorer pre- and postnatal outcomes in the general population, as well as those with cCHD. These disparities are likely driven by structural racism, disparities in social determinants of health, and provider bias, which further compound negative brain development outcomes. This review discusses how aberrant brain development in cCHD early in life is affected by reduced access to quality care (ie, prenatal care and testing, postnatal care) due to divestment in non-White neighbourhoods (eg, redlining) and food insecurity, differences in insurance status, location of residence, and perceived interpersonal racism and bias that disproportionately affects pregnant people of colour who have fewer economic resources. Suggestions are discussed for moving forward with implementing strategies in medical education, clinical care, research, and gaining insight into the communities served to combat disparities and bias while promoting cultural humility.

Altered white matter connectivity in children with congenital heart disease with single ventricle physiology

Children born with congenital heart disease (CHD) have seen a dramatic decrease in mortality thanks to surgical innovations. However, there are numerous risk factors associated with CHD that can disrupt neurodevelopment. Recent studies have found that psychological deficits and structural brain abnormalities persist into adulthood. The goal of the current study was to investigate white matter connectivity in early school-age children (6-11 years), born with complex cyanotic CHD (single ventricle physiology), who have undergone Fontan palliation, compared to a group of heart-healthy, typically developing controls (TPC). Additionally, we investigated associations between white matter tract connectivity and measures on a comprehensive neuropsychological battery within each group. Our results suggest CHD patients exhibit widespread decreases in white matter connectivity, and the extent of these decreases is related to performance in several cognitive domains. Analysis of network topology showed that hub distribution was more extensive and bilateral in the TPC group. Our results are consistent with previous studies suggesting perinatal ischemia leads to white matter lesions and delayed maturation.

Hippocampal volume and cognitive performance in children with congenital heart disease

BACKGROUND

Congenital heart disease (CHD) is associated with an increased risk of brain abnormalities. Studies indicate a particular vulnerability of the hippocampus to hypoxia and inflammation. Yet, information regarding the hippocampus and its relation to cognitive function in school-age children with CHD remains scarce.

METHODS

Children who underwent cardiopulmonary bypass surgery for CHD (N = 17) and healthy controls (N = 14) at 10 years of age underwent neurodevelopmental assessment and cerebral magnetic resonance imaging to measure IQ, working memory performance and hippocampal volume.

RESULTS

IQ was significantly lower in children with CHD compared to controls (98 vs 112, P = 0.02). Children with CHD showed worse working memory performance with significantly lower scores in the letter-number sequencing test (P = 0.02). After adjusting for total brain volume, hippocampal volume was smaller in children with CHD compared to controls (P < 0.01). Smaller hippocampal volume was associated with lower IQ (P = 0.04), and digit span scaled score (P = 0.03), but not with other working memory tests (P > 0.1).

CONCLUSION

This study suggests that the hippocampus may be particularly susceptible in children with CHD thereby contributing to cognitive impairments. Further research is necessary to understand the contribution of the hippocampus to cognitive impairments in children with CHD.

IMPACT

IQ is significantly lower in school-age children with congenital heart disease compared to controls. Working memory performance seems to be worse in children with congenital heart disease. Smaller hippocampal volume is associated with lower IQ and seems to be associated with lower working memory performance. The study adds knowledge on the etiology of cognitive impairments in school-age children with congenital heart disease.

Neuroimaging and Cerebrovascular Changes in Fetuses with Complex Congenital Heart Disease

Background: Congenital heart diseases (CHDs) are often associated with significant neurocognitive impairment and neurological delay. This study aims to elucidate the correlation between type of CHD and Doppler velocimetry and to investigate the possible presence of fetal brain abnormalities identified by magnetic resonance imaging (MRI). Methods: From July 2010 to July 2020, we carried out a cross-sectional study of 63 singleton pregnancies with a diagnosis of different types of complex CHD: LSOL (left-sided obstructive lesions; RSOL (right-sided obstructive lesions) and MTC (mixed type of CHD). All patients underwent fetal echocardiography, ultrasound evaluation, a magnetic resonance of the fetal brain, and genetic counseling. Results: The analysis of 63 fetuses shows statistically significant results in Doppler velocimetry among the different CHD groups. The RSOL group leads to higher umbilical artery (UA-PI) pressure indexes values, whereas the LSOL group correlates with significantly lower values of the middle cerebral artery (MCA-PI) compared to the other subgroups (p = 0.036), whereas the RSOL group shows a tendency to higher pulsatility indexes in the umbilical artery (UA-PI). A significant correlation has been found between a reduced head circumference (HC) and the presence of brain injury at MRI (p = 0.003). Conclusions: Congenital left- and right-sided cardiac obstructive lesions are responsible for fetal hemodynamic changes and brain growth impairment. The correct evaluation of the central nervous system (CNS) in fetuses affected by CHD could be essential as prenatal screening and the prediction of postnatal abnormalities.

Neonatal frontal-limbic connectivity is associated with externalizing behaviours in toddlers with Congenital Heart Disease

Children with Congenital Heart Disease (CHD) are at increased risk of neurodevelopmental impairments. The neonatal antecedents of impaired behavioural development are unknown. 43 infants with CHD underwent presurgical brain diffusion-weighted MRI [postmenstrual age at scan median (IQR) = 39.29 (38.71-39.71) weeks] and a follow-up assessment at median age of 22.1 (IQR 22.0-22.7) months in which parents reported internalizing and externalizing problem scores on the Child Behaviour Checklist. We constructed structural brain networks from diffusion-weighted MRI and calculated edge-wise structural connectivity as well as global and local brain network features. We also calculated presurgical cerebral oxygen delivery, and extracted perioperative variables, socioeconomic status at birth and a measure of cognitively stimulating parenting. Lower degree in the right inferior frontal gyrus (partial ρ = -0.687, p < 0.001) and reduced connectivity in a frontal-limbic sub-network including the right inferior frontal gyrus were associated with higher externalizing problem scores. Externalizing problem scores were unrelated to neonatal clinical course or home environment. However, higher internalizing problem scores were associated with earlier surgery in the neonatal period (partial ρ = -0.538, p = 0.014). Our results highlight the importance of frontal-limbic networks to the development of externalizing behaviours and provide new insights into early antecedents of behavioural impairments in CHD.

Corpus callosum size by neurosonography in fetuses with congenital heart defect and relationship with expected pattern of brain oxygen supply

OBJECTIVE

To evaluate corpus callosum (CC) size by neurosonography (NSG) in fetuses with an isolated major congenital heart defect (CHD) and explore the association of CC size with the expected pattern of in-utero oxygen supply to the brain.

METHODS

A total of 56 fetuses with postnatally confirmed isolated major CHD and 56 gestational-age-matched controls were included. Fetuses with CHD were stratified into two categories according to the main expected pattern of cerebral arterial oxygen supply: Class A, moderately to severely reduced oxygen supply (left outflow tract obstruction and transposition of the great arteries) and Class B, near normal or mildly impaired oxygenated blood supply to the brain (other CHD). Transvaginal NSG was performed at 32-36 weeks in all fetuses to evaluate CC length, CC total area and areas of CC subdivisions in the midsagittal plane.

RESULTS

CHD fetuses had a significantly smaller CC area as compared to controls (7.91 ± 1.30 vs 9.01 ± 1.44 mm² ; P < 0.001), which was more pronounced in the most posterior part of the CC. There was a significant linear trend for reduced CC total area across the three clinical groups, with CHD Class-A cases showing more prominent changes (controls, 9.01 ± 1.44 vs CHD Class B, 8.18 ± 1.21 vs CHD Class A, 7.53 ± 1.33 mm² ; P < 0.05).

CONCLUSIONS

Fetuses with major CHD had a smaller CC compared with controls, and the difference was more marked in the CHD subgroup with expected poorer brain oxygenation. Sonographic CC size could be a clinically feasible marker of abnormal white matter development in CHD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

MRI studies of brain size and growth in individuals with congenital heart disease

Congenital heart disease (CHD) is the most frequent congenital abnormality. Most infants born with CHD now survive. However, survivors of CHD are at increased risk of neurodevelopmental impairment, which may be due to impaired brain development in the fetal and neonatal period. Magnetic resonance imaging (MRI) provides objective measures of brain volume and growth. Here, we review MRI studies assessing brain volume and growth in individuals with CHD from the fetus to adolescence. Smaller brain volumes compared to healthy controls are evident from around 30 weeks gestation in fetuses with CHD and are accompanied by increased extracerebral cerebrospinal fluid. This impaired brain growth persists after birth and throughout childhood to adolescence. Risk factors for impaired brain growth include reduced cerebral oxygen delivery in utero, longer time to surgery and increased hospital stay. There is increasing evidence that smaller total and regional brain volumes in this group are associated with adverse neurodevelopmental outcome. However, to date, few studies have assessed the association between early measures of cerebral volume and neurodevelopmental outcome in later childhood. Large prospective multicentre studies are required to better characterise the relationship between brain volume and growth, clinical risk factors and subsequent cognitive, motor, and behavioural impairments in this at-risk population.

Individualized brain development and cognitive outcome in infants with congenital heart disease

Infants with congenital heart disease are at risk of neurodevelopmental impairments, the origins of which are currently unclear. This study aimed to characterize the relationship between neonatal brain development, cerebral oxygen delivery and neurodevelopmental outcome in infants with congenital heart disease. A cohort of infants with serious or critical congenital heart disease (N = 66; N = 62 born ≥37 weeks) underwent brain MRI before surgery on a 3T scanner situated on the neonatal unit. T2-weighted images were segmented into brain regions using a neonatal-specific algorithm. We generated normative curves of typical volumetric brain development using a data-driven technique applied to 219 healthy infants from the Developing Human Connectome Project (dHCP). Atypicality indices, representing the degree of positive or negative deviation of a regional volume from the normative mean for a given gestational age, sex and postnatal age, were calculated for each infant with congenital heart disease. Phase contrast angiography was acquired in 53 infants with congenital heart disease and cerebral oxygen delivery was calculated. Cognitive and motor abilities were assessed at 22 months (N = 46) using the Bayley scales of Infant and Toddler Development-Third Edition. We assessed the relationship between atypicality indices, cerebral oxygen delivery and cognitive and motor outcome. Additionally, we examined whether cerebral oxygen delivery was associated with neurodevelopmental outcome through the mediating effect of brain volume. Negative atypicality indices in deep grey matter were associated with both reduced neonatal cerebral oxygen delivery and poorer cognitive abilities at 22 months across the whole sample. In infants with congenital heart disease born ≥37 weeks, negative cortical grey matter and total tissue volume atypicality indices, in addition to deep grey matter structures, were associated with poorer cognition. There was a significant indirect relationship between cerebral oxygen delivery and cognition through the mediating effect of negative deep grey matter atypicality indices across the whole sample. In infants born ≥37 weeks, cortical grey matter and total tissue volume atypicality indices were also mediators of this relationship. In summary, lower cognitive abilities in toddlers with congenital heart disease were associated with smaller grey matter volumes before cardiac surgery. The aetiology of poor cognition may encompass poor cerebral oxygen delivery leading to impaired grey matter growth. Interventions to improve cerebral oxygen delivery may promote early brain growth and improve cognitive outcomes in infants with congenital heart disease.