Processing Speed Partially Mediates Executive Function Impairments in Adolescents with Congenital Heart Disease: Results from a Prospective Cohort Study

OBJECTIVE

To assess processing speed, fine motor function, attention, and executive function (EF) impairments in adolescents with complex congenital heart disease (CHD) who underwent open-heart surgery during infancy.

STUDY DESIGN

We administered a comprehensive neuropsychological test battery evaluating 5 EF domains: working memory, inhibition, cognitive flexibility, fluency, and planning and primary neurodevelopmental processes (PNPs): processing speed, fine motor function, and attention. The sample included 100 adolescents with complex CHD from a previous University Children's Hospital Zurich study, with 104 healthy controls for comparison. We generated scores for each EF domain and computed an EF summary score. Group comparisons and associations were analyzed with multiple regression, accounting for parental education. Mediation analysis explored how PNPs mediate the effect between a CHD diagnosis and EF.

RESULTS

In adolescents with complex CHD all EF domains and the EF summary score were impaired (β=0.20 to 0.37, all P<0.05). Furthermore, they exhibited slower processing speed (β=0.27, P<0.01) than healthy controls, with no differences in attention (β=-0.07, P=0.34) and fine motor function (β=0.08, P=0.34). Processing speed showed a strong association with the EF summary score (β=0.60, P<0.001) and partially mediated the relationship between CHD diagnosis and the EF summary score (β=0.37, 95% CI [0.24, 0.50], P<0.001).

CONCLUSION

Adolescents with complex CHD show difficulties in EFs and processing speed. Notably, processing speed is strongly associated with EFs and partly accounts for EFs disparities between patients and healthy controls. Early detection and interventions for processing speed difficulties may improve EF outcomes in these patients.

Stress Markers, Executive Functioning, and Resilience Among Early Adolescents With Complex Congenital Heart Disease

Importance

Infants with complex congenital heart disease (cCHD) may experience prolonged and severe stress when undergoing open heart surgery. However, little is known about long-term stress and its role in neurodevelopmental impairments in this population.

Objective

To investigate potential differences between early adolescents aged 10 to 15 years with cCHD and healthy controls in physiological stress markers by hair analysis, executive function (EF) performance, and resilience.

Design, Setting, and Participants

This single-center, population-based case-control study was conducted at the University Children's Hospital Zurich, Switzerland. Patients with different types of cCHD who underwent cardiopulmonary bypass surgery during the first year of life and who did not have a genetic disorder were included in a prospective cohort study between 2004 and 2012. A total of 178 patients were eligible for assessment at ages 10 to 15 years. A control group of healthy term-born individuals was cross-sectionally recruited. Data assessment was between 2019 and 2021. Statistical analysis was performed from January to April 2023.

Exposure

Patients with cCHD who underwent infant open heart surgery.

Main Outcomes and Measures

Physiological stress markers were quantified by summing cortisol and cortisone concentrations measured with liquid chromatography with tandem mass spectrometry in a 3-centimeter hair strand. EFs were assessed with a neuropsychological test battery to produce an age-adjusted EF summary score. Resilience was assessed with a standardized self-report questionnaire.

Results

The study included 100 patients with cCHD and 104 controls between 10 and 15 years of age (mean [SD] age, 13.3 [1.3] years); 110 (53.9%) were male and 94 (46.1%) were female. When adjusting for age, sex, and parental education, patients had significantly higher sums of hair cortisol and cortisone concentrations (β, 0.28 [95% CI, 0.12 to 0.43]; P < .001) and lower EF scores (β, -0.36 [95% CI, -0.49 to -0.23]; P < .001) than controls. There was no group difference in self-reported resilience (β, -0.04 [95% CI, -0.23 to 0.12]; P = .63). A significant interaction effect between stress markers and EFs was found, indicating a stronger negative association in patients than controls (β, -0.65 [95% CI, -1.15 to -0.15]; P = .01). The contrast effects were not significant in patients (β, -0.21 [95% CI, -0.43 to -0.00]; P = .06) and controls (β, 0.09 [95% CI, -0.11 to 0.30]; P = .38).

Conclusions and Relevance

This case-control study provides evidence for altered physiological stress levels in adolescents with cCHD and an association with poorer EF. These results suggest that future studies are needed to better understand the neurobiological mechanisms and timing of alterations in the stress system and its role in neurodevelopment.

White matter microstructure and executive functions in congenital heart disease from childhood to adulthood: A pooled case-control study

Congenital heart disease (CHD) patients are at risk for alterations in the cerebral white matter microstructure (WMM) throughout development. It is unclear whether the extent of WMM alterations changes with age, especially during adolescence when the WMM undergoes rapid maturation. We investigated differences in WMM between patients with CHD and healthy controls from childhood until early adulthood in a pooled sample of children, adolescents, and young adults. The association between WMM and EF was assessed. Patients with CHD (N=78) and controls (N=137) between 9 and 32 years of age underwent diffusion tensor imaging and an executive function test-battery. Mean fractional anisotropy (FA) was calculated for each white matter tract. Linear regression tested age and group effects (CHD vs control) and their interaction on FA. Relative Variable Importance (RI) estimated the independent contribution of tract FA, presence of CHD, CHD complexity, and parental education to the variability in EF. Mean FA was lower in patients compared to controls in almost all tracts (p between 0.057 and <0.001). WMM alterations in patients were not different depending on age (all interaction effects p>0.074). Predictors of EF were CHD group (RI=43%), parental education (RI=23%), CHD complexity (RI=10%), FA of the hippocampal cingulum (RI=6%) and FA of the corticospinal tract (RI=6%). The lack of group-FA-interactions indicates that the extent of altered FA remains similar across age. Altered FA is associated with EF impairments. CHD is a chronic disease with cerebral and neurocognitive impairments persisting into adulthood and, thus, long-term follow-up programs may improve overall outcome for this population.

Functional networks of working memory abilities in children with complex congenital heart disease: a sleep EEG study

Working memory is frequently impaired in children with complex congenital heart disease (CHD), but little is known about the functional neuronal correlates. Sleep slow wave activity (SWA; 1-4.5 Hz EEG power) has previously been shown to reliably map neurofunctional networks of cognitive abilities in children with and without neurodevelopmental impairments. This study investigated whether functional networks of working memory abilities are altered in children with complex CHD using EEG recordings during sleep. Twenty-one children with complex CHD (aged 10.9 [SD: 0.3] years) and 17 typically-developing peers (10.5 [0.7] years) completed different working memory tasks and an overnight high-density sleep EEG recording (128 electrodes). The combined working memory score tended to be lower in children with complex CHD (CHD group: -0.44 [1.12], typically-developing group: 0.55 [1.24], d = 0.59, p = .06). The working memory score and sleep SWA of the first hour of deep sleep were correlated over similar brain regions in both groups: Strong positive associations were found over prefrontal and fronto-parietal brain regions - known to be part of the working memory network - and strong negative associations were found over central brain regions. Within these working memory networks, the associations between working memory abilities and sleep SWA (r between -.36 and .58, all p < .03) were not different between the two groups (no interactions, all p > .05). The current findings suggest that sleep SWA reliably maps working memory networks in children with complex CHD and that these functional networks are generally preserved in these patients.

Association of cerebellar volume with cognitive and motor function in adults with congenital heart disease

INTRODUCTION

Patients with congenital heart disease (CHD) are at risk for cognitive and motor function impairments, brain injury, and smaller total brain volumes. The specific vulnerability of the cerebellum and its role in cognitive and motor functions in adults with congenital heart disease is not well defined.

METHODS

Forty-three patients with CHD and 53 controls between 18 and 32 years underwent brain magnetic resonance imaging and cognitive, executive (EF), and motor function assessment. Cerebellar volumes were obtained using EasyMeasure and SUIT Toolbox. Associations between cerebellar volumes and cognitive and motor function were calculated using linear models.

RESULTS

General cognitive and pure motor functions were lower in patients compared to controls (P < 0.05). Executive functions were within the normal range. While total cerebellar volumes and the anterior lobes were similar in patients and controls (P > 0.1), the posterior cerebellar lobe was smaller in patients with more complex CHD (P = 0.006). Smaller posterior cerebellar gray matter was not associated with cognitive functions. Smaller anterior cerebellar gray matter was not significantly related to motor functions (P > 0.1).

CONCLUSION

In adults with CHD, cerebellar volume was largely unimpaired. Patients with more complex CHD may be vulnerable to changes in the posterior cerebellar gray matter. We found no significant contribution of cerebellar gray matter to cognitive and motor impairments. More advanced imaging techniques are necessary to clarify the contribution of the cerebellum to cognitive and motor functions.

Counting on random number generation: Uncovering mild executive dysfunction in congenital heart disease

Congenital heart disease (CHD) is associated with various neurocognitive deficits, particularly targeting executive functions (EFs), of which random number generation (RNG) is one indicator. RNG has, however, never been investigated in CHD. We administered the Mental Dice Task (MDT) to 67 young adults with CHD and 55 healthy controls. This 1-minute-task requires the generation of numbers 1 to 6 in a random sequence. RNG performance was correlated with a global EF score. Participants underwent MRI to examine structural-volumetric correlates of RNG. Compared to controls, CHD patients showed increased backward counting, reflecting deficient inhibition of automatized behavior. They also lacked a small-number bias (higher frequency of small relative to large numbers). RNG performance was associated with global EF scores in both groups. In CHD patients, MRI revealed an inverse association of counting bias with most of the volumetric measurements and the amount of small numbers was positively associated with corpus callosum volume, suggesting callosal involvement in the "pseudoneglect in number space". In conclusion, we found an impaired RNG performance in CHD patients, which is associated with brain volumetric measures. RNG, reportedly resistant to learning effects, may be an ideal task for the longitudinal assessment of EFs in patients with CHD.

Somatic growth in children with congenital heart disease at 10 years of age: Risk factors and longitudinal growth

BACKGROUND

Children with congenital heart disease (CHD) are at risk of impaired growth.

AIMS

To describe height, weight, head circumference (HC), and body mass index (BMI) at 10 years and identify risk factors for altered longitudinal growth in children with CHD.

STUDY DESIGN

Growth parameters were evaluated from birth until 10 years using z-scores. The impact of cardiac and noncardiac factors on longitudinal growth was investigated.

SUBJECTS

A total of 135 children with different types of CHD who underwent cardiopulmonary bypass surgery, no genetic disorder.

OUTCOME MEASURES

Head circumference, weight, height and BMI.

RESULTS

At 10 years, z-scores for height and BMI did not differ from the Swiss population (P > 0.1). Z-scores for weight and HC were significantly below the norm (-0.38 and - 0.71, P < 0.01). From 1 to 10 years, all growth parameters except BMI increased significantly (P ≤ 0.001, BMI: P = 0.14). Lower gestational age and longer length of hospitalization were associated with either impaired head circumference or length at 10 years, while lower socioeconomic status was associated with higher BMI and weight at 10 years (all P < 0.05).

CONCLUSION

Despite partial catch-up, somatic growth remains impaired in children with CHD with weight and HC below the norm at 10 years. The only cardiac factor associated with impaired longitudinal growth was duration of hospital stay. Furthermore, lower socioeconomic background may pose a risk of overweight at older age. Close monitoring of growth parameters and parental counselling in all CHD children is advisable beyond early childhood to ensure optimal somatic growth.

Impact of the COVID-19 pandemic on children with and without risk for neurodevelopmental impairments

AIM

To examine how the ongoing COVID-19 pandemic impacts child well-being and family functioning, particularly among children at risk for neurodevelopmental impairments.

METHODS

Families of 73 typically developing children, 54 children born very preterm (VPT) and 73 children with congenital heart disease (CHD) from two prospective cohort studies were assessed prior to (mean age: 10.4 [SD: 1.2] years) and during (mean age: 12.8 [SD: 2.0] years) the pandemic, more specifically, in April/May 2020. Child well-being and family functioning were assessed with validated, parent-reported questionnaires and tested with linear mixed models. Group comparison of child distress and parental concerns related to medical implications of COVID-19 and homeschooling, assessed with 5-point Likert scales, was done with Mann-Whitney U tests.

RESULTS

Children's psychological well-being and family functioning (both, p < 0.001) decreased significantly during the pandemic, irrespective of group. Children with CHD were reported to be more concerned about becoming infected with SARS-CoV-2 than were others. Child distress due to homeschooling and parents' concerns about children's academic achievements were significantly higher in VPT and CHD children than in typically developing peers (all p < 0.001).

CONCLUSION

The COVID-19 pandemic substantially impacts the whole family and leads to additional distress in families with children at risk for neurodevelopmental impairments. These families should receive individualised counselling and assistance from healthcare providers and schools during the pandemic.

Brain volumes in adults with congenital heart disease correlate with executive function abilities

Congenital heart disease is the most common birth defect, and patients are at risk for neurodevelopmental impairment and brain abnormalities. Yet, little is known about the link between brain volumes and cognitive function in adults with congenital heart disease. Forty-four patients and 53 controls between 18 and 32 years underwent brain magnetic resonance imaging and cognitive testing, assessed with an intelligence quotient and executive function global score. Associations between brain volumes and cognitive function were calculated using linear models. Cognitive function in patients was within the normal range (intelligence quotient: 97.74 (10.76)). Total brain volume was significantly smaller in patients compared to controls (1067.26 (113.53) vs 1113.04 (97.88) cm³, P < 0.01), irrespective of cardiac factors (heart defect complexity, cyanosis, cardiopulmonary bypass: all P > 0.4). After adjusting for total brain volume, only corpus callosum volume remained significantly smaller (P = 0.03). Smaller total brain volume was associated with poorer overall executive functioning (P = 0.02) and inhibition (P < 0.01), in both patients and controls. The association between total brain volume and overall executive functioning was moderated by parental socioeconomic status (lower socioeconomic status was associated with a stronger association between brain volume and EF; interaction P = 0.03). In adults with congenital heart disease, despite normal intelligence quotient, brain volume alterations persist into adulthood and are related to executive functioning, in particular inhibitory control. Adults coming from low socioeconomic background and with altered brain volumes are especially vulnerable and should thus be followed-up during adulthood to ensure optimal social and educational support.

Executive function and brain development in adolescents with severe congenital heart disease (Teen Heart Study): protocol of a prospective cohort study

INTRODUCTION

Congenital heart disease (CHD) is the most frequent congenital malformation. With recent advances in medical care, the majority of patients with CHD survive into adulthood. As a result, interest has shifted towards the neurodevelopmental outcome of these patients, and particularly towards the early detection and treatment of developmental problems. A variety of mild to moderate cognitive impairments as well as emotional and behavioural problems has been observed in this population. However, a more detailed assessment of the various domains of executive function and their association with structural and functional brain development is lacking. Therefore, the current study will examine all domains of executive function and brain development in detail in a large sample of children and adolescents with CHD and healthy control children.

METHODS AND ANALYSIS

A total of 192 children and adolescents with CHD aged 10-15 years, who participated in prospective cohort studies at the University Children's Hospital Zurich, will be eligible for this study. As a control group, approximately 100 healthy children will be enrolled. Primary outcome measures will include executive function abilities, while secondary outcomes will consist of other neurodevelopmental measures, including intelligence, processing speed, attention, fine motor abilities and brain development. An MRI will be performed to assess structural and functional brain development. Linear regression analyses will be applied to investigate group differences and associations between executive function performance and neurodevelopmental measures.

ETHICS AND DISSEMINATION

This study is supported by the Swiss National Science Foundation (SNF 32003B_172914) and approved by the ethical committee of the Canton Zurich (KEK 2019-00035). Written informed consent will be obtained from all the parents and from children aged 14 years or older. Findings from this study will be published in peer-reviewed journals and presented at national and international conferences for widespread dissemination of the results.

White matter injury in term neonates with congenital heart diseases: Topology & comparison with preterm newborns

BACKGROUND

Neonates with congenital heart disease (CHD) are at high risk of punctate white matter injury (WMI) and impaired brain development. We hypothesized that WMI in CHD neonates occurs in a characteristic distribution that shares topology with preterm WMI and that lower birth gestational age (GA) is associated with larger WMI volume.

OBJECTIVE

(1) To quantitatively assess the volume and location of WMI in CHD neonates across three centres. (2) To compare the volume and spatial distribution of WMI between term CHD neonates and preterm neonates using lesion mapping.

METHODS

In 216 term born CHD neonates from three prospective cohorts (mean birth GA: 39 weeks), WMI was identified in 86 neonates (UBC: 29; UCSF: 43; UCZ: 14) on pre- and/or post-operative T1 weighted MRI. WMI was manually segmented and volumes were calculated. A standard brain template was generated. Probabilistic WMI maps (total, pre- and post-operative) were developed in this common space. Using these maps, WMI in the term CHD neonates was compared with that in preterm neonates: 58 at early-in-life (mean postmenstrual age at scan 32.2 weeks); 41 at term-equivalent age (mean postmenstrual age at scan 40.1 weeks).

RESULTS

The total WMI volumes of CHD neonates across centres did not differ (p = 0.068): UBC (median = 84.6 mm³, IQR = 26-174.7 mm³); UCSF (median = 104 mm³, IQR = 44-243 mm³); UCZ (median = 121 mm³, IQR = 68-200.8 mm³). The spatial distribution of WMI in CHD neonates showed strong concordance across centres with predilection for anterior and posterior rather than central lesions. Predominance of anterior lesions was apparent on the post-operative WMI map relative to the pre-operative map. Lower GA at birth predicted an increasing volume of WMI across the full cohort (41.1 mm³ increase of WMI per week decrease in gestational age; 95% CI 11.5-70.8; p = 0.007), when accounting for centre and heart lesion. While WMI in term CHD and preterm neonates occurs most commonly in the intermediate zone/outer subventricular zone there is a paucity of central lesions in the CHD neonates relative to preterms.

CONCLUSIONS

WMI in term neonates with CHD occurs in a characteristic topology. The spatial distribution of WMI in term neonates with CHD reflects the expected maturation of pre-oligodendrocytes such that the central regions are less vulnerable than in the preterm neonates.

Neurodevelopmental Profiles of Children with Congenital Heart Disease at School Age

OBJECTIVES

To assess 6-year neurodevelopmental outcomes in a current cohort of children with congenital heart disease (CHD) who underwent cardiopulmonary bypass surgery (CPB), and to determine risk factors for adverse outcomes.

STUDY DESIGN

Outcomes were examined in 233 prospectively enrolled children with CHD (including 64 with a recognized genetic disorder) who underwent CPB between 2004 and 2009. Follow-up assessment included standardized neurologic, motor, and cognitive tests. Variables were collected prospectively, and multiple regression analysis was performed to determine independent risk factors for adverse outcome.

RESULTS

The mean patient age at assessment was 6.3 years (range, 5.1-6.8 years). IQ was lower in children with a genetic disorder (median, 55; range, 17-115) compared with children without a genetic disorder (median, 95; range, 47-135; P < .001). Cognitive and motor performance also were lower in children without a genetic disorder compared with the norm (P < .01 for both). The prevalence of children without a genetic disorder performing below -2 SD (IQ 70) was higher than the norm (5.3% vs 2.3%; P = .008), and the prevalence of poor motor performance (<10th percentile) ranged from 21.2% to 41.1% (P < .01 for all). Significant independent risk factors for poor neurodevelopmental outcome included a genetic disorder, longer length of intensive care stay, lower birth weight, postoperative seizures, and lower socioeconomic status.

CONCLUSIONS

Current cohorts of children with CHD undergoing CPB show favorable outcomes but remain at risk for long-term neurodevelopmental impairments, particularly those with a genetic disorder and a complicated postoperative course. Close neurodevelopmental surveillance is necessary to provide early therapeutic support.

Replicate Measurements of Haemoglobin Mass during a Single Day are Feasible and Precise

Duplicate haemoglobin mass (Hb_mass) measurements are recommended before and after altitude training sojourns to identify individual adaptations in athletes with a high level of certainty. Duplicate measurements reduce typical error (TE) and disclose measurement outliers, but are usually made on separate days, which is not a practical protocol for routine services in elite sport settings. The aim of this study was therefore to investigate whether it is safe (carboxyhaemoglobin<10%) to measure Hb_mass twice on the same day and to compare TE with measurements made on separate days. 18 healthy men completed 3 different procedures to measure Hb_mass twice a day with the carbon monoxide rebreathing method: A (Hb_mass measured twice within 6 h), B (dito A, combined with 1 h of hyperoxic training between the tests), C (dito B, within 2 h). First Hb_mass measurements of the 3 test days served as procedure D. Carboxyhaemoglobin did not exceed 10% in any procedure. TE and confidence limits for procedures A, B, C and D were 1.4% (1.0-2.1%), 1.1% (0.8-1.7%), 1.3% (1.0-2.0%) and 1.5% (1.2-2.1%), respectively. Duplicate measurements of Hb_mass on the same day are feasible and show TE similar to triplicate measurements on separate days.

Tapering for marathon and cardiac autonomic function

The purpose of this study was to investigate changes in post-exercise heart rate recovery (HRR) and heart rate variability (HRV) during an overload-tapering paradigm in marathon runners and examine their relationship with running performance. 9 male runners followed a training program composed of 3 weeks of overload followed by 3 weeks of tapering (-33 ± 7%). Before and after overload and during tapering they performed an exhaustive running test (T(lim)). At the end of this test, HRR variables (e.g. HRR during the first 60 s; HRR(60 s)) and vagal-related HRV indices (e.g. RMSSD(5-10 min)) were examined. T(lim) did not change during the overload training phase (603 ± 105 vs. 614 ± 132 s; P = 0.992), but increased (727 ± 185 s; P = 0.035) during the second week of tapering. Compared with overload, RMSSD(5-10 min) (7.6 ± 3.3 vs. 8.6 ± 2.9 ms; P = 0.045) was reduced after the 2(nd) week of tapering. During tapering, the improvements in T(lim) were negatively correlated with the change in HRR(60 s) (r = -0.84; P = 0.005) but not RMSSD(5-10 min) (r = -0.21; P = 0.59). A slower HRR during marathon tapering may be indicative of improved performance. In contrast, the monitoring of changes in HRV as measured in the present study (i.e. after exercise on a single day), may have little or no additive value.