Reduced cortical volume and thickness and their relationship to medical and operative features in post-Fontan children and adolescents

Neurodevelopmental Outcomes for Individuals With Congenital Heart Disease: Updates in Neuroprotection, Risk-Stratification, Evaluation, and Management: A Scientific Statement From the American Heart Association

Over the past decade, new research has advanced scientific knowledge of neurodevelopmental trajectories, factors that increase neurodevelopmental risk, and neuroprotective strategies for individuals with congenital heart disease. In addition, best practices for evaluation and management of developmental delays and disorders in this high-risk patient population have been formulated based on literature review and expert consensus. This American Heart Association scientific statement serves as an update to the 2012 statement on the evaluation and management of neurodevelopmental outcomes in children with congenital heart disease. It includes revised risk categories for developmental delay or disorder and an updated list of factors that increase neurodevelopmental risk in individuals with congenital heart disease according to current evidence, including genetic predisposition, fetal and perinatal factors, surgical and perioperative factors, socioeconomic disadvantage, and parental psychological distress. It also includes an updated algorithm for referral, evaluation, and management of individuals at high risk. Risk stratification of individuals with congenital heart disease with the updated categories and risk factors will identify a large and growing population of survivors at high risk for developmental delay or disorder and associated impacts across the life span. Critical next steps must include efforts to prevent and mitigate developmental delays and disorders. The goal of this scientific statement is to inform health care professionals caring for patients with congenital heart disease and other key stakeholders about the current state of knowledge of neurodevelopmental outcomes for individuals with congenital heart disease and best practices for neuroprotection, risk stratification, evaluation, and management.

Cerebral Spinal Fluid Volumetrics and Paralimbic Predictors of Executive Dysfunction in Congenital Heart Disease: A Machine Learning Approach Informing Mechanistic Insights

The relationship between increased cerebral spinal fluid (CSF) ventricular compartments, structural and microstructural dysmaturation, and executive function in patients with congenital heart disease (CHD) is unknown. Here, we leverage a novel machine-learning data-driven technique to delineate interrelationships between CSF ventricular volume, structural and microstructural alterations, clinical risk factors, and sub-domains of executive dysfunction in adolescent CHD patients. We trained random forest regression models to predict measures of executive function (EF) from the NIH Toolbox, the Delis-Kaplan Executive Function System (D-KEFS), and the Behavior Rating Inventory of Executive Function (BRIEF) and across three subdomains of EF - mental flexibility, working memory, and inhibition. We estimated the best parameters for the random forest algorithm via a randomized grid search of parameters using 10-fold cross-validation on the training set only. The best parameters were then used to fit the model on the full training set and validated on the test set. Algorithm performance was measured using root-mean squared-error (RMSE). As predictors, we included patient clinical variables, perioperative clinical measures, microstructural white matter (diffusion tensor imaging- DTI), and structural volumes (volumetric magnetic resonance imaging- MRI). Structural white matter was measured using along-tract diffusivity measures of 13 inter-hemispheric and cortico-association fibers. Structural volumes were measured using FreeSurfer and manual segmentation of key structures. Variable importance was measured by the average Gini-impurity of each feature across all decision trees in which that feature is present in the model, and functional ontology mapping (FOM) was used to measure the degree of overlap in feature importance for each EF subdomain and across subdomains. We found that CSF structural properties (including increased lateral ventricular volume and reduced choroid plexus volumes) in conjunction with proximate cortical projection and paralimbic-related association white matter tracts that straddle the lateral ventricles and distal paralimbic-related subcortical structures (basal ganglia, hippocampus, cerebellum) are predictive of two-specific subdomains of executive dysfunction in CHD patients: cognitive flexibility and inhibition. These findings in conjunction with combined RF models that incorporated clinical risk factors, highlighted important clinical risk factors, including the presence of microbleeds, altered vessel volume, and delayed PDA closure, suggesting that CSF-interstitial fluid clearance, vascular pulsatility, and glymphatic microfluid dynamics may be pathways that are impaired in CHD, providing mechanistic information about the relationship between CSF and executive dysfunction.

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.

Fontan Circulation Associated Organ Abnormalities Beyond the Heart, Lungs, Liver, and Gut: A Systematic Review

Introduction

Patients with a Fontan circulation are at risk for sequelae of Fontan physiology during follow-up. Fontan physiology affects all organ systems and an overview of end-organ damage is needed.

Methods

We performed a systematic review of abnormalities in multiple organ systems for patients with a longstanding Fontan circulation. We searched online databases for articles describing abnormalities in multiple organ systems. Cardio-pulmonary abnormalities, protein losing enteropathy, and Fontan associated liver disease have already extensively been described and were excluded from this systematic review.

Results

Our search returned 5,704 unique articles. After screening, we found 111 articles relating to multiple organ systems. We found abnormalities in, among others, the nervous system, pituitary, kidneys, and musculoskeletal system. Pituitary edema—relating to the unique pituitary vasculature- may affect the thyroid axis. Renal dysfunction is common. Creatinine based renal function estimates may be inappropriate due to myopenia. Both lean muscle mass and bone mineral density are decreased. These abnormalities in multiple organ systems may be related to Fontan physiology, cyanosis, iatrogenic factors, or lifestyle.

Conclusions

Health care providers should be vigilant for hypothyroidism, visual or hearing deficits, and sleep disordered breathing in Fontan patients. We recommend including cystatin C for assessment of renal function. This review may aid health care providers and guide future research.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021232461, PROSPERO, identifier: CRD42021232461.

Neurodevelopmental and Mental Health Outcomes in Patients With Fontan Circulation: A State-of-the-Art Review

Children, adolescents and adults living with Fontan circulation face numerous neurological and developmental challenges. As the population with complex CHD increases thanks to outstanding improvement in medical and surgical care, the long-term developmental and mental health sequelae have become a public health priority in pediatric and congenital cardiology. Many patients with a Fontan circulation experience difficulty in areas of cognition related to attention and executive functioning, visual spatial reasoning and psychosocial development. They are also at high risk for mental health morbidities, particularly anxiety disorders and depression. Several hemodynamic risk factors, beginning during the fetal period, may influence outcomes and yield to abnormal brain growth and development. Brain injury such as white matter lesions, stroke or hemorrhage can occur before, during, or after surgery. Other sociodemographic and surgical risk factors such as multiple catheterizations and surgeries and prolonged hospital stay play a detrimental role in patients' neurodevelopmental prognosis. Prevention and intervention to optimize long-term outcomes are critical in the care of this vulnerable population with complex CHD.

Cognitive and Attentional Function in Children with Hypoplastic Left Heart Syndrome: A Pilot Study

While survival for children with hypoplastic left heart syndrome (HLHS) has improved, compromised cardiac output and oxygen delivery persist, and children show cognitive deficits. Most research has assessed young children on broad cognitive indices; less is known about specific indices in older youth. In this pilot study, cognitive function and attention in youth ages 8 to 16 years with HLHS (n = 20) was assessed with the Wechsler Intelligence Scale for Children - Fifth Edition (WISC-V) and NIH Toolbox Cognition Battery (NTCB); parents completed the Child Behavior Checklist. Children scored significantly lower than normative means on the WISC-V Full Scale IQ, Verbal Comprehension, Visual Spatial, Working Memory, and Processing Speed indices, and the NTCB Fluid Cognition Composite; effect sizes ranged from medium to large. Attention problems had a large significant effect. Child age corresponded to lower visual spatial scores. Findings highlight the importance of assessing multiple cognitive indices for targeted intervention and investigating age and disease factors as potential correlates in larger samples.

Abnormal Right-Hemispheric Sulcal Patterns Correlate with Executive Function in Adolescents with Tetralogy of Fallot

Neurodevelopmental disabilities are the most common noncardiac conditions in patients with congenital heart disease (CHD). Executive function skills have been frequently observed to be decreased among children and adults with CHD compared with peers, but a neuroanatomical basis for the association is yet to be identified. In this study, we quantified sulcal pattern features from brain magnetic resonance imaging data obtained during adolescence among 41 participants with tetralogy of Fallot (ToF) and 49 control participants using a graph-based pattern analysis technique. Among patients with ToF, right-hemispheric sulcal pattern similarity to the control group was decreased (0.7514 vs. 0.7553, P = 0.01) and positively correlated with neuropsychological testing values including executive function (r = 0.48, P < 0.001). Together these findings suggest that sulcal pattern analysis may be a useful marker of neurodevelopmental risk in patients with CHD. Further studies may elucidate the mechanisms leading to different alterations in sulcal patterning.

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.

Neurocognitive Dysfunction and Smaller Brain Volumes in Adolescents and Adults With a Fontan Circulation

BACKGROUND

Neurocognitive outcomes beyond childhood in people with a Fontan circulation are not well defined. This study aimed to investigate neurocognitive functioning in adolescents and adults with a Fontan circulation and associations with structural brain injury, brain volumetry, and postnatal clinical factors.

METHODS

In a binational study, participants with a Fontan circulation without a preexisting major neurological disability were prospectively recruited from the Australia and New Zealand Fontan Registry. Neurocognitive function was assessed by using Cogstate software in 107 participants with a Fontan circulation and compared with control groups with transposition of the great arteries (n=50) and a normal circulation (n=41). Brain MRI with volumetric analysis was performed in the participants with a Fontan circulation and compared with healthy control data from the ABIDE I and II (Autism Brain Imaging Data Exchange) and PING (Pediatric Imaging, Neurocognition, and Genetics) data repositories. Clinical data were retrospectively collected.

RESULTS

Of the participants with a Fontan circulation who had a neurocognitive assessment, 55% were male and the mean age was 22.6 years (SD 7.8). Participants with a Fontan circulation performed worse in several areas of neurocognitive function compared with those with transposition of the great arteries and healthy controls (P<0.05). Clinical factors associated with worse neurocognitive outcomes included more inpatient days during childhood, younger age at Fontan surgery, and longer time since Fontan procedure (P<0.05). Adults with a Fontan circulation had more marked neurocognitive dysfunction than adolescents with a Fontan circulation in 2 domains (psychomotor function, P=0.01 and working memory, P=0.02). Structural brain injury was present in the entire Fontan cohort; the presence of white matter injury was associated with worse paired associate learning (P<0.001), but neither the presence nor severity of infarct, subcortical gray matter injury, and microhemorrhage was associated with neurocognitive outcomes. Compared with healthy controls, people with a Fontan circulation had smaller global brain volumes (P<0.001 in all regions) and smaller regional brain volumes in most cerebral cortical regions (P<0.05). Smaller global brain volumes were associated with worse neurocognitive functioning in several domains (P<0.05). A significant positive association was also identified between global brain volumes and resting oxygen saturations (P≤0.04).

CONCLUSIONS

Neurocognitive impairment is common in adolescents and adults with a Fontan circulation and is associated with smaller gray and white matter brain volume. Understanding modifiable factors that contribute to brain injury to optimize neurocognitive function is paramount.

Regional Brain Growth Trajectories in Fetuses with Congenital Heart Disease

OBJECTIVE

Congenital heart disease (CHD) is associated with abnormal brain development in utero. We applied innovative fetal magnetic resonance imaging (MRI) techniques to determine whether reduced fetal cerebral substrate delivery impacts the brain globally, or in a region-specific pattern. Our novel design included two control groups, one with and the other without a family history of CHD, to explore the contribution of shared genes and/or fetal environment to brain development.

METHODS

From 2014 to 2018, we enrolled 179 pregnant women into 4 groups: "HLHS/TGA" fetuses with hypoplastic left heart syndrome (HLHS) or transposition of the great arteries (TGA), diagnoses with lowest fetal cerebral substrate delivery; "CHD-other," with other CHD diagnoses; "CHD-related," healthy with a CHD family history; and "optimal control," healthy without a family history. Two MRIs were obtained between 18 and 40 weeks gestation. Random effect regression models assessed group differences in brain volumes and relationships to hemodynamic variables.

RESULTS

HLHS/TGA (n = 24), CHD-other (50), and CHD-related (34) groups each had generally smaller brain volumes than the optimal controls (71). Compared with CHD-related, the HLHS/TGA group had smaller subplate (-13.3% [standard error = 4.3%], p < 0.01) and intermediate (-13.7% [4.3%], p < 0.01) zones, with a similar trend in ventricular zone (-7.1% [1.9%], p = 0.07). These volumetric reductions were associated with lower cerebral substrate delivery.

INTERPRETATION

Fetuses with CHD, especially those with lowest cerebral substrate delivery, show a region-specific pattern of small brain volumes and impaired brain growth before 32 weeks gestation. The brains of fetuses with CHD were more similar to those of CHD-related than optimal controls, suggesting genetic or environmental factors also contribute. ANN NEUROL 2021;89:143-157.

Cognitive Function in Pediatric Hypoplastic Left Heart Syndrome: Systematic Review and Meta-Analysis

OBJECTIVE

Despite surgical palliation, children with hypoplastic left heart syndrome (HLHS) have compromised cardiac functioning and increased risk for cognitive deficits. We quantitatively reviewed the empirical data from this literature.

METHODS

The present meta-analysis included 13 studies reporting cognitive function for children with HLHS between the ages of 2 years and 6 months and 17 years that used standardized assessments of Full Scale IQ (FSIQ), Verbal IQ (VIQ), and Performance IQ (PIQ). Differences in cognitive function were assessed relative to normative data, and we examined sample mean age and publication year as moderators.

RESULTS

Large effects were found for FSIQ (g = -.87, 95% CI [-1.10, -.65], M = 86.88) and PIQ (g = -.89, 95% CI [-1.11, -.68], M = 86.56), and a medium effect was found for VIQ (g = -.61, 95% CI [-.84, -.38], M = 90.82). All models demonstrated significant heterogeneity. Meta-regression analyses of effect size via Hedges' g on child age revealed a significant effect on FSIQ (coefficient = -.07, 95% CI [-.12, -.01], p < .01, R2 = .40) indicating a loss of 1.1 FSIQ points across studies with each increased year of mean sample age.

CONCLUSIONS

Deficits in FSIQ may reflect chronic brain injury or failure to make expected gains as children age. This review highlights the importance of early intervention in this population, and the need for longitudinal studies analyzing more specific domains of cognitive function and potential moderators.

Imaging of complications following Fontan circulation in children - diagnosis and surveillance

The Fontan operation is performed for various cardiac lesions with single-ventricle physiology. The survival rate of Fontan patients is increasing for adolescents and young adults, with an expected 30-year survival of >80%. Medical health care providers including specialists in organ systems and pediatric radiologists need to improve their knowledge about the Fontan circulation and the various organ complications to monitor care. In this review the author explains the basic anatomical and functional features of Fontan palliation and gives an overview of the multiple long-term organ complications that might present in the pediatric population. These include decreased physical capacity, ventricular dysfunction, atrioventricular valve regurgitation and arrhythmia, as well as protein-losing enteropathy, plastic bronchitis, growth/bone composition disturbances, renal dysfunction, and the recently recognized and important liver fibrosis (Fontan-associated liver disease). Neuropsychological and behavioral deficits occur frequently. This review focuses on the key role of radiology in making the diagnosis of these complications, monitoring therapy and predicting outcomes in the pediatric age group. The author discusses how and when radiology is important in Fontan patients, as well as how new techniques enabling quantitative measures in imaging with US, MRI and CT are adapted for pediatric use, and how they contribute to urgently needed surveillance strategies.

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.

Evaluation and Management of the Child and Adult With Fontan Circulation: A Scientific Statement From the American Heart Association

It has been 50 years since Francis Fontan pioneered the operation that today bears his name. Initially designed for patients with tricuspid atresia, this procedure is now offered for a vast array of congenital cardiac lesions when a circulation with 2 ventricles cannot be achieved. As a result of technical advances and improvements in patient selection and perioperative management, survival has steadily increased, and it is estimated that patients operated on today may hope for a 30-year survival of >80%. Up to 70 000 patients may be alive worldwide today with Fontan circulation, and this population is expected to double in the next 20 years. In the absence of a subpulmonary ventricle, Fontan circulation is characterized by chronically elevated systemic venous pressures and decreased cardiac output. The addition of this acquired abnormal circulation to innate abnormalities associated with single-ventricle congenital heart disease exposes these patients to a variety of complications. Circulatory failure, ventricular dysfunction, atrioventricular valve regurgitation, arrhythmia, protein-losing enteropathy, and plastic bronchitis are potential complications of the Fontan circulation. Abnormalities in body composition, bone structure, and growth have been detected. Liver fibrosis and renal dysfunction are common and may progress over time. Cognitive, neuropsychological, and behavioral deficits are highly prevalent. As a testimony to the success of the current strategy of care, the proportion of adults with Fontan circulation is increasing. Healthcare providers are ill-prepared to tackle these challenges, as well as specific needs such as contraception and pregnancy in female patients. The role of therapies such as cardiovascular drugs to prevent and treat complications, heart transplantation, and mechanical circulatory support remains undetermined. There is a clear need for consensus on how best to follow up patients with Fontan circulation and to treat their complications. This American Heart Association statement summarizes the current state of knowledge on the Fontan circulation and its consequences. A proposed surveillance testing toolkit provides recommendations for a range of acceptable approaches to follow-up care for the patient with Fontan circulation. Gaps in knowledge and areas for future focus of investigation are highlighted, with the objective of laying the groundwork for creating a normal quality and duration of life for these unique individuals.

Hippocampal alterations and functional correlates in adolescents and young adults with congenital heart disease

There is a high prevalence of neurodevelopmental impairments in individuals living with congenital heart disease (CHD) and the neural correlates of these impairments are not yet fully understood. Recent studies have shown that hippocampal volume and shape differences may provide unique biomarkers for neurodevelopmental disorders. The hippocampus is vulnerable to early life injury, especially in populations at risk for hypoxemia or hemodynamic instability such as in neonates with CHD. We compared hippocampal gray and white matter volume and morphometry between youth born with CHD (n = 50) aged 16-24 years and healthy peers (n = 48). We also explored whether hippocampal gray and white matter volume and morphometry are associated with executive function and self-regulation deficits. To do so, participants underwent 3T brain magnetic resonance imaging and completed the self-reported Behavior Rating Inventory of Executive Function-Adult version. We found that youth with CHD had smaller hippocampal volumes (all statistics corrected for false discovery rate; q < 0.05) as compared to controls. We also observed significant smaller surface area bilaterally and inward displacement on the left hippocampus predominantly on the ventral side (q < 0.10) in the CHD group that were not present in the controls. Left CA1 and CA2/3 were negatively associated with working memory (p < .05). Here, we report, for the first-time, hippocampal morphometric alterations in youth born with CHD when compared to healthy peers, as well as, structure-function relationships between hippocampal volumes and executive function. These differences may reflect long lasting alterations in brain development specific to individual with CHD.

Altered White Matter Microstructure Correlates with IQ and Processing Speed in Children and Adolescents Post-Fontan

OBJECTIVE

To compare white matter microstructure in children and adolescents with single ventricle who underwent the Fontan procedure with healthy controls, and to explore the association of white matter injury with cognitive performance as well as patient and medical factors.

STUDY DESIGN

Fontan (n = 102) and control subjects (n = 47) underwent diffusion tensor imaging (DTI) at ages 10-19 years. Mean DTI measures (fractional anisotropy, radial diffusivity, axial diffusivity, and mean diffusivity) were calculated for 33 fiber tracts from standard white matter atlases. Voxel-wise group differences in DTI measures were assessed using Tract-Based Spatial Statistics. Associations of regional fractional anisotropy with IQ and processing speed as well as medical characteristics were examined.

RESULTS

Subjects with Fontan, compared with controls, had reduced bilateral regional and voxel-wise fractional anisotropy in multiple white matter tracts along with increased regional radial diffusivity in several overlapping tracts; regional mean diffusivity differed in 2 tracts. The groups did not differ in voxel-wise radial diffusivity or mean diffusivity. Among subjects with Fontan, fractional anisotropy in many tracts correlated positively with Full-Scale Intelligence Quotient and processing speed, although similar findings were absent in controls. Lower mean fractional anisotropy in various tracts was associated with more complications in the first operation, a greater number of total operations, and history of neurologic event.

CONCLUSIONS

Children and adolescents who have undergone the Fontan procedure have widespread abnormalities in white matter microstructure. Furthermore, white matter microstructure in several tracts is associated with cognitive performance and operative and medical history characteristics.