Brain immaturity is associated with brain injury before and after neonatal cardiac surgery with high-flow bypass and cerebral oxygenation monitoring

Establishing Optimal Control Cohorts for Phase 1 Trials: Retrospective Analysis of Clinical and Biological Outcomes in Neonates and Infants Undergoing Two-Ventricle Repair

Phase 1 trials are primarily conducted to evaluate the safety and feasibility of new interventions, usually without recruiting control patients. This retrospective study aims to characterize clinical and biological outcomes in historical and contemporary cases of neonates and infants undergoing two-ventricle repair to facilitate future secondary endpoint analyses for such trials. This retrospective study included neonates/infants (ages ≤ 6 months) who underwent two-ventricle repair between 2015 and 2021 using the same criteria as our phase 1 trial (n = 199). Patients were allocated into the ventricular septal defect (n = 61), the Tetralogy of Fallot (TOF, n = 88), and the transposition of the great arteries (n = 50) groups with an additional comparison between two eras (2015-2019 vs. 2020-2021). Patient characteristics and most variables assessed were different between the three diagnostic groups indicating the importance of diagnostic matching for secondary analyses. Although the era did not alter cerebral/somatic oxygenation, ventricular function, neuroimaging findings, and complication rates, we observed improvement of inotropic and/or vasoactive-inotropic scores in all groups during the more recent era. In 2020-2021, the age and the body weight at the operation were higher, and hospital stay was shorter in the TOF group, suggesting the possible impact of the pandemic. Results also indicated that matching altered characteristics such as age at operation that may limit the temporal effects and optimize secondary analyses. Using optimal contemporary cases and historical data based on this study will assist in developing a comprehensive study design for a future efficacy/effectiveness trial.

Cerebral autoregulation monitoring in neonates and infants after cardiac surgery with cardiopulmonary bypass - comparison of single ventricle and biventricular physiology

Introduction

Cardiopulmonary bypass surgery can lead to impaired cerebral autoregulation with the risk for ischemia, hemorrhage and delirium. In particular, infants with single ventricle physiology have altered hemodynamics with persistent veno-arterial shunting, cyanosis and diastolic run-off after surgery, which may have negative effects on cerebral autoregulation.

Methods

Cerebral autoregulation was prospectively monitored in 83 neonates and infants after open heart surgery with cardiopulmonary bypass after admission to the pediatric intensive care unit. Autoregulation indices were determined using near-infrared spectroscopy, correlating regional cortical oxygen saturation and local hemoglobin levels with invasive mean arterial pressure. Intact autoregulation was defined as cerebral oxygenation index (COx) < 0.4 and hemoglobin volume index (HVx) < 0.3. A subgroup analysis was performed between 55 infants after biventricular repair surgery and 15 infants after palliative surgery.

Results

The mean lower limit of autoregulation was 46 ± 6 mmHg (COx) and 46 ± 7 mmHg (HVx). The optimal mean arterial pressure according to cerebral autoregulation was 56 ± 8 mmHg (COx) and 55 ± 7 mmHg (HVx). The mean upper limit was 65 ± 9 mmHg (COx) and 65 ± 8 mmHg (HVx). Intact autoregulation occurred during 84 ± 8% (COx) and 77 ± 10% (HVx) of the monitored time. No significant differences were found in autoregulation parameters between single ventricle and biventricular groups. However, the single ventricle group had significantly lower arterial and cerebral oxygen saturation.

Discussion

A standardized blood pressure management may not be sufficient in children after cardiac surgery due to potentially impaired cerebral autoregulation. Therefore, cerebral autoregulation monitoring should be considered in this patient population.

Effect of Dexmedetomidine on Cerebrovascular Carbon Dioxide Reactivity During Pediatric Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVE

To assess the effects of dexmedetomidine (DEX) on cerebrovascular autoregulation in children with congenital heart disease (CHD) using transcranial color-coded duplex sonography (TCCD).

DESIGN

Randomized controlled trial.

SETTING

This single-center study was conducted at a tertiary care center in Shanghai, China.

PATIENTS

Fifty-nine children aged 0 to 6 years with CHD who underwent cardiac surgery with cardiopulmonary bypass were enrolled.

INTERVENTION

Children were randomly assigned to receive either DEX (DEX group) or normal saline (control group) for 10 minutes following anesthetic induction. Cerebrovascular carbon dioxide reactivity (CVR-CO2) was assessed by adjustment of lung ventilation.

MEASUREMENTS AND MAIN RESULTS

Patients underwent TCCD before and after surgery. CVR-CO2, resistance index (RI), pulsatility index (PI), mean blood flow velocity (Vmean) of the right middle cerebral artery, and regional cerebral oxygen saturation (ScrO2) of the right frontal lobe were measured and analyzed at three distinct time points, resulting in six measurements. Hemodynamic parameters, including heart rate (HR) and mean arterial pressure (MAP), were recorded at each time point. The parameters CVR-CO2 (p = 0.402), PI (p = 0.203), RI (p = 0.290), Vmean (p = 0.290), ScrO2 (p = 0.426), HR (p = 0.522), and MAP (p = 0.236) were comparable between the two groups. In the control group, PI, RI, and HR significantly differed before and after surgery. In the DEX group, RI, Vmean, ScrO2, and HR significantly differed before and after surgery.

CONCLUSIONS

A low loading dose of DEX did not compromise CVR-CO2 in children with CHD undergoing cardiac surgery with cardiopulmonary bypass.

Cerebral blood flow dynamics during cardiac surgery in infants

BACKGROUND

In this pilot study, we investigated continuous cerebral blood flow velocity measurements to explore cerebrovascular hemodynamics in infants with congenital heart disease undergoing cardiac surgery.

METHODS

A non-invasive transfontanellar cerebral Doppler monitor (NeoDoppler) was used to monitor 15 infants (aged eight days to nine months) during cardiac surgery with cardiopulmonary bypass. Numerical and visual analyses were conducted to assess trends and events in Doppler measurements together with standard monitoring equipment. The mean flow index, calculated as the moving Pearson correlation between mean arterial pressure and time averaged velocity, was utilized to evaluate dynamic autoregulation. Two levels of impaired autoregulation were defined (Mean flow index >0.3/0.45), and percentage of time above these limits were calculated.

RESULTS

High quality recordings were achieved during 90.6% of the monitoring period. There was a significant reduction in time averaged velocity in all periods of cardiopulmonary bypass. All patients showed a high percentage of time with impaired dynamic autoregulation, with Mean flow index >0.3 and 0.45: 73.71% ± 9.06% and 65.16% ± 11.27% respectively. Additionally, the system promptly detected hemodynamic events.

CONCLUSION

Continuous transfontanellar cerebral Doppler monitoring could become an additional tool in enhancing cerebral monitoring in infants during cardiac surgery.

IMPACT

This pilot study demonstrates the feasibility of continuous transfontanellar Doppler monitoring of cerebral blood flow velocities during cardiac surgery in infants. It also demonstrates a high proportion of time with impaired cerebral autoregulation during cardiac surgery based on the Mean flow index. Continuous transfontanellar Doppler could become a useful tool to improve cerebral monitoring and provide new pathophysiological insight.

Outcomes following deep hypothermic circulatory arrest versus antegrade cerebral perfusion during aortic arch reconstruction

Objective

The optimal method for cerebral protection during aortic arch reconstruction in neonates and infants is unknown. We compare the outcomes of deep hypothermic circulatory arrest and selective antegrade cerebral perfusion strategies in neonatal and infant cardiac surgery.

Methods

We retrospectively identified all patients aged less than 1 year who underwent aortic arch reconstruction from 2012 to 2023. Patients were categorized on the cerebral perfusion strategy used during their procedure. Comparative analyses of perioperative and outcome variables were conducted to assess differences between cerebral protection strategies. A secondary analysis further stratifying by complexity of repair was performed. Examples of "complex" repair included the Norwood procedure, and "simple" repairs included isolated arch reconstructions. Adjusted regression models were used to identify specific outcomes associated with cerebral perfusion strategy used.

Results

There were 165 cases included in our cohort (114 [69%] selective antegrade cerebral perfusions and 51 [31%] deep hypothermic circulatory arrests). Overall, hospital mortality was 7% (selective antegrade cerebral perfusion 9% vs deep hypothermic circulatory arrest 2%, P = .17). There were 6 total neurologic events in 4 patients after surgery in the selective antegrade cerebral perfusion group and none in the deep hypothermic circulatory arrest group. Irrespective of the cerebral perfusion strategy, there were no differences in mortality, stroke, seizures, renal failure, and catheterization reinterventions observed after surgery. This finding held true even when stratifying cerebral perfusion methods by complexity of repair. Regression analysis showed no associations for cerebral perfusion strategy with any outcome even after adjusting for age and complexity of repair.

Conclusions

There were no significant short-term differences and a low rate of neurologic events in both groups during aortic arch reconstruction among neonates and infants. Longer follow-up is necessary to evaluate the impact of cerebral perfusion strategy on neurocognitive development later in life.

Association between subcortical nuclei volume changes and cognition in preschool-aged children with tetralogy of Fallot after corrective surgery: a cross-sectional study

BACKGROUND

Neurocognitive disorders frequently occur in patients with cyanotic congenital heart disease (CCHD) because of the hemodynamic abnormalities induced by preoperative cardiac structural changes. We aimed to evaluate subcortical nuclei volume changes and cognition in postoperative tetralogy of Fallot (TOF) children, and analyze their relationship with preoperative cardiac structural changes.

METHODS

This case-control study involved thirty-six children with repaired TOF and twenty-nine healthy controls (HCs). We utilized three-dimensional (3D) T1-weighted high-resolution structural images alongside the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition (WPPSI-IV) to evaluate the cognitive differences between the TOF and HC group.

RESULTS

We observed notable differences in subcortical nuclei volume between the TOF and HC group, specifically in the left amygdala nucleus (LAM, TOF: 1292.60 ± 155.57; HC: 1436.27 ± 140.62, p < 0.001), left thalamus proper nucleus (LTHA, TOF: 6771.54 ± 666.03; HC: 7435.36 ± 532.84, p < 0.001), and right thalamus proper nucleus (RTHA, TOF: 6514.61 ± 715.23; HC: 7162.94 ± 554.60, p < 0.001). Furthermore, a diminished integrity of LAM ( β:-19.828, 95% CI: -36.462, -3.193), which showed an inverse relationship with the size of the preoperative ventricular septal defect (VSD), correlated with lower working memory indices in children with TOF.

CONCLUSIONS

Our findings indicate that subcortical nuclei structural injuries possibly potentially stemming from cardiac anatomical abnormalities, are associated with impaired working memory in preschool-aged children with TOF. The LAM in particular may serve as a potential biomarker for neurocognitive deficits in TOF, offering predictive value for future neurodevelopmental outcomes, and shedding light on the neurophysiological mechanisms of these cognitive impairments.

Neuromonitoring practices for neonates with congenital heart disease: a scoping review

Neonates with congenital heart disease (CHD) are at risk for adverse neurodevelopmental outcomes. This scoping review summarizes neuromonitoring methods in neonates with CHD. We identified 84 studies investigating the use of near-infrared spectroscopy (NIRS) (n = 37), electroencephalography (EEG) (n = 20), amplitude-integrated electroencephalography (aEEG) (n = 10), transcranial Doppler sonography (TCD) (n = 6), and multimodal monitoring (n = 11). NIRS was used to evaluate cerebral oxygenation, identify risk thresholds and adverse events in the intensive care unit (ICU), and outcomes. EEG was utilized to screen for seizures and to predict adverse outcomes. Studies of aEEG have focused on characterizing background patterns, detecting seizures, and outcomes. Studies of TCD have focused on correlation with short-term clinical outcomes. Multimodal monitoring studies characterized cerebral physiologic dynamics. Most of the studies were performed in single centers, had a limited number of neonates (range 3-183), demonstrated variability in neuromonitoring practices, and lacked standardized approaches to neurodevelopmental testing. We identified areas of improvement for future research: (1) large multicenter studies to evaluate developmental correlates of neuromonitoring practices; (2) guidelines to standardize neurodevelopmental testing methodologies; (3) research to address geographic variation in resource utilization; (4) integration and synchronization of multimodal monitoring; and (5) research to establish a standardized framework for neuromonitoring techniques across diverse settings. IMPACT: This scoping review summarizes the literature regarding neuromonitoring practices in neonates with congenital heart disease (CHD). The identification of low cerebral oxygenation thresholds with NIRS may be used to identify neonates at risk for adverse events in the ICU or adverse neurodevelopmental outcomes. Postoperative neuromonitoring with continuous EEG screening for subclinical seizures and status epilepticus, allow for early and appropriate therapy. Future studies should focus on enrolling larger multicenter cohorts of neonates with CHD with a standardized framework of neuromonitoring practices in this population. Postoperative neurodevelopmental testing should utilize standard assessments and testing intervals.

Prospective evaluation of acute neurological events after paediatric cardiac surgery

OBJECTIVES

Children with CHD are at heightened risk of neurodevelopmental problems; however, the contribution of acute neurological events specifically linked to the perioperative period is unclear.

AIMS

This secondary analysis aimed to quantify the incidence of acute neurological events in a UK paediatric cardiac surgery population, identify risk factors, and assess how acute neurological events impacted the early post-operative pathway.

METHODS

Post-operative data were collected prospectively on 3090 consecutive cardiac surgeries between October 2015 and June 2017 in 5 centres. The primary outcome of analysis was acute neurological event, with secondary outcomes of 6-month survival and post-operative length of stay. Patient and procedure-related variables were described, and risk factors were statistically explored with logistic regression.

RESULTS

Incidence of acute neurological events after paediatric cardiac surgery in our population occurred in 66 of 3090 (2.1%) consecutive cardiac operations. 52 events occurred with other morbidities including renal failure (21), re-operation (20), cardiac arrest (20), and extracorporeal life support (18). Independent risk factors for occurrence of acute neurological events were CHD complexity 1.9 (1.1-3.2), p = 0.025, longer operation times 2.7 (1.6-4.8), p < 0.0001, and urgent surgery 3.4 (1.8-6.3), p < 0.0001. Unadjusted comparison found that acute neurological event was linked to prolonged post-operative hospital stay (median 35 versus 9 days) and poorer 6-month survival (OR 13.0, 95% CI 7.2-23.8).

CONCLUSION

Ascertainment of acute neurological events relates to local measurement policies and was rare in our population. The occurrence of acute neurological events remains a suitable post-operative metric to follow for quality assurance purposes.

Prevalence and Risk Factors for Cerebral Palsy in Children With Congenital Heart Disease Based on Risk of Surgical Mortality

BACKGROUND

Children with congenital heart disease (CHD) have a higher prevalence of motor impairment secondary to brain injury, resulting in cerebral palsy (CP). The purpose of this study is to determine the prevalence of CP in CHD in a single-center cohort, stratify risk based on surgical mortality using Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) categories and identify risk factors.

METHODS

Retrospective cohort study of pediatric patients registered in the University of Florida (UF) Society of Thoracic Surgeons Congenital Heart Surgery database from 2006 to 2017 with a diagnosis of CHD who continued follow-up for more than two years at UF.

RESULTS

A total of 701 children with CHD met inclusion criteria. Children identified to have CP were 54 (7.7%). Most common presentation was spastic hemiplegic CP with a Gross Motor Function Classification System of level 2. Analysis of surgical and intensive care factors between the two groups showed that children with CHD and CP had longer time from admission to surgery (P = 0.003), higher STAT categories 4 and 5 (P = 0.038), and higher frequency of brain injury and seizures (P < 0.001). Developmental disabilities and rehabilitation needs were significantly greater for children with CHD and CP when compared with those with CHD alone (P < 0.001).

CONCLUSIONS

In our cohort, 7.7% children with CHD develop CP; this is significantly higher than the 2010 US population estimate of 0.3%. Our study suggests higher STAT categories, brain injury, and seizures are associated with developing CP in children with CHD.

Fetal circulatory physiology and brain development in complex congenital heart disease: A multi-modal imaging study

OBJECTIVE

Fetuses with complex congenital heart disease have altered physiology, contributing to abnormal neurodevelopment. The effects of altered physiology on brain development have not been well studied. We used multi-modal imaging to study fetal circulatory physiology and brain development in hypoplastic left heart syndrome (HLHS) and d-transposition of the great arteries (TGA).

METHODS

This prospective, cross-sectional study investigated individuals with fetal congenital heart disease and controls undergoing fetal echocardiography and fetal brain MRI. MRI measured total brain volume and cerebral oxygenation by the MRI quantification method T2*. Indexed cardiac outputs (CCOi) and vascular impedances were calculated by fetal echocardiography. Descriptive statistics assessed MRI and echocardiogram measurement relationships by physiology.

RESULTS

Sixty-six participants enrolled (control = 20; HLHS = 25; TGA = 21), mean gestational age 33.8 weeks (95% CI: 33.3-34.2). Total brain volume and T2* were significantly lower in fetuses with cardiac disease. CCOi was lower in HLHS, correlating with total brain volume - for every 10% CCOi increase, volume increased 8 mm3 (95% CI: 1.78-14.1; p = 0.012). Echocardiography parameters and cerebral oxygenation showed no correlation. TGA showed no CCOi or aortic output correlation with MRI measures.

CONCLUSIONS

In HLHS, lower cardiac output is deleterious to brain development. Our findings provide insight into the role of fetal cardiovascular physiology in brain health.

Monitoring of cerebral blood flow autoregulation: physiologic basis, measurement, and clinical implications

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20-55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes.

Gut microbiota-derived cholic acid mediates neonatal brain immaturity and white matter injury under chronic hypoxia

Chronic hypoxia, common in neonates, disrupts gut microbiota balance, which is crucial for brain development. This study utilized cyanotic congenital heart disease (CCHD) patients and a neonatal hypoxic rat model to explore the association. Both hypoxic rats and CCHD infants exhibited brain immaturity, white matter injury (WMI), brain inflammation, and motor/learning deficits. Through 16s rRNA sequencing and metabolomic analysis, a reduction in B. thetaiotaomicron and P. distasonis was identified, leading to cholic acid accumulation. This accumulation triggered M1 microglial activation and inflammation-induced WMI. Administration of these bacteria rescued cholic acid-induced WMI in hypoxic rats. These findings suggest that gut microbiota-derived cholic acid mediates neonatal WMI and brain inflammation, contributing to brain immaturity under chronic hypoxia. Therapeutic targeting of these bacteria provides a non-invasive intervention for chronic hypoxia patients.

Distinct profiles of cerebral oxygenation in focal vs. secondarily generalized EEG seizures in children undergoing cardiac surgery

Objectives

Seizures are common in children undergoing cardiopulmonary bypass (CPB). Cerebral oxygen saturation (ScO2) by near-infrared spectroscopy is routinely monitored in many centers, but the relations between the levels and changes of ScO2 and brain injuries remain incompletely understood. We aimed to analyze the postoperative profiles of ScO2 and cerebral blood flow velocity in different types of EEG seizures in relation to brain injuries on MRI.

Methods

We monitored continuous EEG and ScO2 in 337 children during the first 48 h after CPB, which were analyzed in 3 h periods. Cerebral blood flow peak systolic velocity (PSV) in the middle cerebral artery was measured daily by transcranial Doppler. Postoperative cerebral MRI was performed before hospital discharge.

Results

Based on the occurrence and spreading types of seizures, patients were divided into three groups as patients without seizures (Group N; n = 309), those with focal seizures (Group F; n = 13), or with secondarily generalized seizures (Group G; n = 15). There were no significant differences in the onset time and duration of seizures and incidence of status epilepticus between the two seizures groups (Ps ≥ 0.27). ScO2 increased significantly faster across Group N, Group G, and Group F during the 48 h (p < 0.0001) but its overall levels were not significantly different among the three groups (p = 0.30). PSV was significantly lower (p = 0.003) but increased significantly faster (p = 0.0003) across Group N, Group G, and Group F. Group F had the most severe brain injuries and the highest incidence of white matter injuries on MRI among the three groups (Ps ≤ 0.002).

Conclusion

Postoperative cerebral oxygenation showed distinct profiles in secondarily generalized and particularly focal types of EEG seizures in children after CPB. A state of 'overshooting' ScO2 with persistently low PSV was more frequently seen in those with focal seizures and more severe brain injury. Information from this study may have important clinical implications in detecting brain injuries when monitoring cerebral oxygenation in this vulnerable group of children after CPB.

Language brain responses and neurodevelopmental outcome in preschoolers with congenital heart disease: A fNIRS study

Neurodevelopmental disabilities affect up to 50% of survivors of congenital heart disease (CHD). Language difficulties are frequently identified during preschool period and can lead to academic, social, behavioral, and emotional difficulties. Structural brain alterations are associated with poorer neurodevelopmental outcomes in patients with CHD during infancy, childhood, and adolescence. However, evidence is lacking about the functional brain activity in children with CHD and its relationship with neurodevelopment. This study therefore aimed to characterize brain responses during a passive story-listening task in 3-year-old children with CHD, and to investigate the relationship between functional brain patterns of language processing and neurodevelopmental outcomes. To do so, we assessed hemodynamic concentration changes, using functional near-infrared spectroscopy (fNIRS), and neurodevelopmental outcomes, using the Wechsler Preschool and Primary Scale of Intelligence - 4th Edition (WPPSI-IV), in children with CHD (n = 19) and healthy controls (n = 23). Compared to their healthy peers, children with CHD had significantly lower scores on the Verbal comprehension index (VCI), the Vocabulary acquisition index (VAI), the General ability index (GAI), and the Information and the Picture Naming subtests of the WPPSI-IV. During the passive story-listening task, healthy controls showed significant hemodynamic brain responses in the temporal and the temporal posterior regions, with stronger activation in the temporal posterior than in the temporal regions. In contrast, children with CHD showed reduced activation in the temporal posterior regions compared to controls, with no difference of activation between regions. Reduced brain responses in the temporal posterior regions were also correlated with lower neurodevelopmental outcomes in both groups. This is the first study that reveals reduced brain functional responses in preschoolers with CHD during a receptive language task. It also suggests that the temporal posterior activation could be a potential brain marker of cognitive development. These findings provide support for the feasibility of identifying brain correlates of neurodevelopmental vulnerabilities in children with CHD.

Neurological injury in pediatric heart disease: A review of developmental and acquired risk factors and management considerations

Medical and surgical advancements have improved survival in children with acquired and congenital heart disease (CHD), but the burden of neurological morbidity is high. Brain disorders associated with CHD include white matter injury, stroke, seizure, and neurodevelopmental delays. While genetics and disease-specific factors play a substantial role in early brain injury, therapeutic management of the heart disease intensifies the risk. There is a growing interest in understanding how to reduce brain injury and improve neurodevelopmental outcomes in cardiac diseases. Pediatric neurologists serve a vital role in care teams managing these complex patients, providing interpretation of neuromonitoring and imaging, managing neurologic emergencies, assisting with neuro prognostication, and identifying future research aims.

Perioperative Brain Injury in Relation to Early Neurodevelopment Among Children with Severe Congenital Heart Disease: Results from a European Collaboration

OBJECTIVE

To examine the relationship between perioperative brain injury and neurodevelopment during early childhood in patients with severe congenital heart disease (CHD).

STUDY DESIGN

One hundred and seventy children with CHD and born at term who required cardiopulmonary bypass surgery in the first 6 weeks after birth were recruited from 3 European centers and underwent preoperative and postoperative brain MRIs. Uniform description of imaging findings was performed and an overall brain injury score was created, based on the sum of the worst preoperative or postoperative brain injury subscores. Motor and cognitive outcomes were assessed with the Bayley Scales of Infant and Toddler Development Third Edition at 12 to 30 months of age. The relationship between brain injury score and clinical outcome was assessed using multiple linear regression analysis, adjusting for CHD severity, length of hospital stay (LOS), socioeconomic status (SES), and age at follow-up.

RESULTS

Neither the overall brain injury score nor any of the brain injury subscores correlated with motor or cognitive outcome. The number of preoperative white matter lesions was significantly associated with gross motor outcome after correction for multiple testing (P = .013, β = -0.50). SES was independently associated with cognitive outcome (P < .001, β = 0.26), and LOS with motor outcome (P < .001, β = -0.35).

CONCLUSION

Preoperative white matter lesions appear to be the most predictive MRI marker for adverse early childhood gross motor outcome in this large European cohort of infants with severe CHD. LOS as a marker of disease severity, and SES influence outcome and future intervention trials need to address these risk factors.

Brain injury and neurodevelopmental outcomes in children undergoing surgery for congenital heart disease

Objectives

Brain injury is commonly seen on magnetic resonance imaging in infants with complex congenital heart disease. The impact of perioperative brain injury on neurodevelopmental outcomes is not well understood. We evaluate the association of brain injury and other markers on neurodevelopmental outcomes in patients undergoing surgery for congenital heart surgery during infancy.

Methods

Term newborns with infant cardiac surgery performed between 2008 and 2019 at a single tertiary center, and both preoperative and postoperative brain magnetic resonance imaging were included. Those with underlying genetic conditions were excluded. Brain injury was characterized using an magnetic resonance imaging scoring system. Neurodevelopmental outcomes were assigned using the Pediatric Stroke Outcome Measure and Glasgow Outcome Scale Extended. Independent risk factors for poor neurodevelopmental outcomes were determined by multivariable Cox regression.

Results

A total of 122 patients were included. New or progressive postoperative brain injury was noted in 69 patients (57%). A total of 101 patients (83%) had at least 1 neurodevelopmental assessment (median age 36 months) with an early assessment (5-24 months) performed in 95 children. Multivariable Cox regression analysis of early neurodevelopmental outcomes identified new stroke on postoperative magnetic resonance imaging to be an independent predictor of poor neurodevelopmental outcome. Postoperative peak lactate was an independent predictor of poor outcome assessed by the Pediatric Stroke Outcome Measure and Glasgow Outcome Scale Extended.

Conclusions

Our study reveals that evidence of new stroke on magnetic resonance imaging after infant congenital heart surgery is a predictor of poor neurodevelopmental outcomes in early childhood. Postoperative lactic acidosis is associated with poor neurodevelopmental outcome and may be a surrogate biomarker for ischemic brain injury.

Prenatal Brain Maturation is Delayed in Neonates with Congenital Diaphragmatic Hernia

OBJECTIVE

To assess brain development in fetuses with congenital diaphragmatic hernia (CDH) using a fetal Total Maturation Score (fTMS).

STUDY DESIGN

This is a retrospective cohort study using data from a single-center clinical registry. Neonates with an antenatal diagnosis of CDH between 2014 and 2020 and prenatal brain magnetic resonance imaging (MRI) (n = 48) were included. We compared our study sample with historical healthy controls (n = 48). The relationship between fTMS and gestational age (GA), as well as the association between fTMS and key prenatal variables and placental pathologic findings, were evaluated.

RESULTS

Compared with healthy controls, neonates with CDH had a significant delay in fTMS (P value <.001). Within the CDH cohort, there was no significant difference in fTMS based on CDH severity, intrathoracic liver position, right vs left CDH, sex, presence of abnormal echocardiogram findings, treatment with extracorporeal membrane oxygenation (ECMO), or in-hospital mortality. Placentas of neonates with CDH had a high proportion of fetal vascular malperfusion (56%) and chronic inflammation (67%), and relatively large placentas had a protective effect on prenatal brain maturation (P value = .025).

CONCLUSIONS

Prenatal brain maturation in neonates with CDH is delayed. Placental pathology may influence fetal brain development. The etiology and clinical impact of prenatal brain immaturity in neonates with CDH warrant further investigation.

Neurological Impact of Slower Rewarming during Bypass Surgery in Infants

BACKGROUND

 Hypothermia is a neuroprotective strategy during cardiopulmonary bypass. Rewarming entailing a rapid rise in cerebral metabolism might lead to secondary neurological sequelae. In this pilot study, we aimed to validate the hypothesis that a slower rewarming rate would lower the risk of cerebral hypoxia and seizures in infants.

METHODS

 This is a prospective, clinical, single-center study. Infants undergoing cardiac surgery in hypothermia were rewarmed either according to the standard (+1°C in < 5 minutes) or a slow (+1°C in > 5-8 minutes) rewarming strategy. We monitored electrocortical activity via amplitude-integrated electroencephalography (aEEG) and cerebral oxygenation by near-infrared spectroscopy during and after surgery.

RESULTS

 Fifteen children in the standard rewarming group (age: 13 days [5-251]) were cooled down to 26.6°C (17.2-29.8) and compared with 17 children in the slow-rewarming group (age: 9 days [4-365]) with a minimal temperature of 25.7°C (20.1-31.4). All neonates in both groups (n = 19) exhibited suppressed patterns compared with 28% of the infants > 28 days (p < 0.05). During rewarming, only 26% of the children in the slow-rewarming group revealed suppressed aEEG traces (vs. 41%; p = 0.28). Cerebral oxygenation increased by a median of 3.5% in the slow-rewarming group versus 1.5% in the standard group (p = 0.9). Our slow-rewarming group revealed no aEEG evidence of any postoperative seizures (0 vs. 20%).

CONCLUSION

 These results might indicate that a slower rewarming rate after hypothermia causes less suppression of electrocortical activity and higher cerebral oxygenation during rewarming, which may imply a reduced risk of postoperative seizures.

Postoperative hypernatremia is associated with worse brain injuries on EEG and MRI following pediatric cardiac surgery

Objectives

Dysnatremia is a common electrolyte disturbance after cardiopulmonary bypass (CPB) surgery for congenital heart disease (CHD) and a known risk factor for adverse neurological events and clinical outcomes. The objective of this study was to evaluate the association of dysnatremia with worse abnormal EEG patterns, brain injuries detected by magnetic resonance imaging (MRI) and early adverse outcomes.

Methods

We monitored continuous EEG in 340 children during the initial 48 h following cardiac surgery. Demographics and clinical characteristics were recorded. Sodium concentrations were measured in the arterial blood gas analysis every 6 h. Hyponatremia and hypernatremia were classified by the average of sodium concentrations over 48 h. Postoperative cerebral MRI was performed before hospital discharge.

Results

In our patient cohort, dysnatremia was present in 46 (13.5%) patients. Among them, hyponatremia occurred in 21 (6.2%) and hypernatremia in 25 (7.4%). When compared to patients with normonatremia, hyponatremia was not associated with EEG abnormalities and early adverse outcomes (Ps ≥ .14). In hypernatremia group, the CPB time was significantly longer and more frequent use of DHCA (Ps ≤ .049). After adjusting for time, CPB time and the use of DHCA, hypernatremia was significantly associated with worse EEG abnormalities (including background, seizures and pathological delta brushes), more severe brain injuries on MRI (Ps ≤ .04) and trended to be associated with longer postoperative mechanical ventilation time (P = .06).

Conclusion

Hypernatremia and hyponatremia were common in children after cardiac surgery. Hypernatremia, but not hyponatremia, was significantly associated with worse EEG abnormalities and more severe brain injuries on MRI and extended postoperative mechanical ventilation time.

Early brain magnetic resonance imaging findings and neurodevelopmental outcome in children with congenital heart disease: A systematic review

AIM

To investigate the association between early brain magnetic resonance imaging (MRI) findings and neurodevelopmental outcome (NDO) in children with congenital heart disease (CHD).

METHOD

A search for studies was conducted in Embase, Medline, Web of Science, Cochrane Central, PsycINFO, and Google Scholar. Observational and interventional studies were included, in which patients with CHD underwent surgery before 2 months of age, a brain MRI scan in the first year of life, and neurodevelopmental assessment beyond the age of 1 year.

RESULTS

Eighteen studies were included. Thirteen found an association between either quantitative or qualitative brain metrics and NDO: 5 out of 7 studies showed decreased brain volume was significantly associated with worse NDO, as did 7 out of 10 studies on brain injury. Scanning protocols and neurodevelopmental tests varied strongly.

INTERPRETATION

Reduced brain volume and brain injury in patients with CHD can be associated with impaired NDO, yet standardized scanning protocols and neurodevelopmental assessment are needed to further unravel trajectories of impaired brain development and its effects on outcome.

Trajectories of neurodevelopment and opportunities for intervention across the lifespan in congenital heart disease

Children with congenital heart disease (CHD) are at increased risk for neurodevelopmental challenges across the lifespan. These are associated with neurological changes and potential acquired brain injury, which occur across a developmental trajectory and which are influenced by an array of medical, sociodemographic, environmental, and personal factors. These alterations to brain development lead to an array of adverse neurodevelopmental outcomes, which impact a characteristic set of skills over the course of development. The current paper reviews existing knowledge of aberrant brain development and brain injury alongside associated neurodevelopmental challenges across the lifespan. These provide a framework for discussion of emerging and potential interventions to improve neurodevelopmental outcomes at each developmental stage.

Commentary on "Brain Injury During Transition in the Newborn With Congenital Heart Disease: Hazards of the Preoperative Period"

BRAIN INJURY DURING TRANSITION IN THE NEWBORN WITH CONGENITAL HEART DISEASE: HAZARDS OF THE PREOPERATIVE PERIOD: Jennifer M. Lynch, J. William Gaynor, Daniel J. Licht Seminars in Pediatric Neurology Volume 28, December 2018, Pages 60-65 Infants born with critical congenital heart disease are at risk for neurodevelopmental morbidities later in life. In-utero differences in fetal circulation lead to vulnerabilities which lead to an increased incidence of stroke, white matter injury, and brain immaturity. Recent work has shown these infants may be most vulnerable to brain injury during the early neonatal period when they are awaiting their cardiac surgeries. Novel imaging and monitoring modalities are being employed to investigate this crucial time period and elucidate the precise timing and cause of brain injury in this population.

Functional measures on PEDI are associated with BSID-3 scales at 2 years, following neonatal surgery

BACKGROUND

Neonates requiring early surgical intervention for major non-cardiac congenital anomalies are at high risk of adverse neurodevelopmental outcomes. Early recognition of potential neuro-developmental delay is critical to facilitate access to early childhood intervention services and therefore maximise the functional capabilities of these children.

AIMS

This study aims to compare Bayley's Scales of Infant and Toddler Development (BSID-3) and the Paediatric Evaluation of Disability Inventory (PEDI) as early screening tools in predicting neuro-developmental disability across multiple domains. In addition, it looks at determining which pre, peri and post-operative risk factors lend themselves to more adverse outcomes.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

Neonates requiring surgical intervention at the Royal Children's Hospital from 2012 to 2018 who subsequently underwent neurodevelopmental assessment at 2 years of age.

OUTCOME MEASURES

The main outcome was the relationship between performance on the PEDI compared with the BSID-3, in 2-year-olds following neonatal surgery.

RESULTS

Parent -reported functional measures across all domains on PEDI strongly related to the more formal measures of cognition, language, and motor development assessed on BSID-3 (p < 0.05).

CONCLUSIONS

The questionnaire-based PEDI tool could be considered a reliable replacement to the formal Bayley (BSID-3) scale in low-risk infants and provide a more accessible means of assessment where there are deficiencies in availability of suitably trained clinicians or limited resource centres.

Critical congenital heart disease beyond HLHS and TGA: neonatal brain injury and early neurodevelopment

BACKGROUND

Characterization of brain injury and neurodevelopmental (ND) outcomes in critical congenital heart disease (cCHD) has primarily focused on hypoplastic left heart syndrome (HLHS) and transposition of the great arteries (TGA). This study reports brain injury and ND outcomes among patients with heterogeneous cCHD diagnoses beyond HLHS and TGA.

METHODS

This prospective cohort study included infants with HLHS, TGA, or heterogenous "Other cCHD" including left- or right-sided obstructive lesions, anomalous pulmonary venous return, and truncus arteriosus. Brain injury on perioperative brain MRI and ND outcomes on the Bayley-II at 30 months were compared.

RESULTS

A total of 218 participants were included (HLHS = 60; TGA = 118; "Other cCHD" = 40, including 8 with genetic syndromes). Pre-operative (n = 209) and post-operative (n = 189) MRI showed similarly high brain injury rates across groups, regardless of cardiopulmonary bypass exposure. At 30 months, participants with "Other cCHD" had lower cognitive scores (p = 0.035) compared to those with HLHS and TGA, though worse ND outcome in this group was driven by those with genetic disorders.

CONCLUSIONS

Frequency of brain injury and neurodevelopmental delay among patients with "Other cCHD" is similar to those with HLHS or TGA. Patients with all cCHD lesions are at risk for impaired outcomes; developmental and genetic screening is indicated.

IMPACT

This study adds to literature on risk of brain injury in patients with critical congenital heart disease (cCHD) diagnoses other than hypoplastic left heart syndrome (HLHS) and transposition of the great arteries (TGA), a heterogenous cohort of patients that has often been excluded from imaging studies. Children with cCHD beyond HLHS and TGA have similarly high rates of acquired brain injury. The high rate of neurodevelopmental impairment in this heterogenous group of cCHD diagnoses beyond HLHS and TGA is primarily driven by patients with comorbid genetic syndromes such as 22q11.2 deletion syndrome.

Perioperative EEG background and discharge abnormalities in children undergoing cardiac surgery: a prospective single-centre observational study

BACKGROUND

We analysed the characteristics of abnormal electroencephalogram (EEG) patterns before, during, and 48 h after cardiac surgery in patients with heterogeneous congenital heart disease to assess their relationship to demographic and perioperative variables and to early patient outcomes.

METHODS

In 437 patients enrolled in a single centre, EEG was evaluated for background (including sleep-wake cycle) and discharge (seizures, spikes/sharp waves, pathological delta brushes) abnormalities. Clinical data (arterial blood pressure, doses of inotropic drugs, and serum lactate concentrations) were recorded every 3 h. Postoperative brain MRI was performed before discharge.

RESULTS

Preoperative, intraoperative, and postoperative EEG was monitored in 139, 215, and 437 patients, respectively. Patients with a degree of preoperative background abnormalities (n=40) had more severe intraoperative and postoperative EEG abnormalities (P<0.0001). Intraoperatively, 106/215 (49.3%) patients progressed into an isoelectric EEG. Longer durations of isoelectric EEG were associated with more severe postoperative EEG abnormalities and brain injury on MRI (Ps≤0.003). Postoperative background abnormalities occurred in 218/437 (49.9%) patients, and 119 (54.6%) of them had not recovered after surgery. Seizures occurred in 36/437 (8.2%) patients, spikes/sharp waves in 359/437 (82.2%), and pathological delta brushes in 9/437 (2.0%). Postoperative EEG abnormalities correlated with degree of brain injury on MRI (Ps≤0.02). Demographic and perioperative variables were significantly correlated with postoperative EEG abnormalities, which in turn correlated with adverse clinical outcomes.

CONCLUSIONS

Perioperative EEG abnormalities occurred frequently and correlated with numerous demographic and perioperative variables and adversely correlated with postoperative EEG abnormalities and early outcomes. The relation of EEG background and discharge abnormalities with long-term neurodevelopmental outcomes remains to be explored.

Cerebral Autoregulation Status in Relation to Brain Injury on Electroencephalogram and Magnetic Resonance Imaging in Children Following Cardiac Surgery

Background Disturbed cerebral autoregulation has been reported in children with congenital heart disease before and during cardiopulmonary bypass surgery, but not after. We sought to characterize the cerebral autoregulation status in the early postoperative period in relation to perioperative variables and brain injuries. Methods and Results A prospective and observational study was conducted in 80 patients in the first 48 hours following cardiac surgery. Cerebral oximetry/pressure index (COPI) was retrospectively calculated as a moving linear correlation coefficient between mean arterial blood pressure and cerebral oxygen saturation. Disturbed autoregulation was defined as COPI >0.3. Correlations of COPI with demographic and perioperative variables as well as brain injuries on electroencephalogram and magnetic resonance imaging and early outcomes were analyzed. Thirty-six (45%) patients had periods of abnormal COPI for 7.81 hours (3.38 hours) either at hypotension (median <45 mm Hg) or hypertension (median >90 mm Hg) or both. Overall, COPI became significantly lower over time, suggesting improved autoregulatory status during the 48 postoperative hours. All of the demographic and perioperative variables were significantly associated with COPI, which in turn was associated with the degree of brain injuries and early outcomes. Conclusions Children with congenital heart disease following cardiac surgery often have disturbed autoregulation. Cerebral autoregulation is at least partly the underlying mechanism of brain injury in those children. Careful clinical management to manipulate the related and modifiable factors, particularly arterial blood pressure, may help to maintain adequate cerebral perfusion and reduce brain injury early after cardiopulmonary bypass surgery. Further studies are warranted to determine the significance of impaired cerebral autoregulation in relation to long-term neurodevelopment outcomes.

Single Ventricle Reconstruction III: Brain Connectome and Neurodevelopmental Outcomes: Design, Recruitment, and Technical Challenges of a Multicenter, Observational Neuroimaging Study

Patients with hypoplastic left heart syndrome who have been palliated with the Fontan procedure are at risk for adverse neurodevelopmental outcomes, lower quality of life, and reduced employability. We describe the methods (including quality assurance and quality control protocols) and challenges of a multi-center observational ancillary study, SVRIII (Single Ventricle Reconstruction Trial) Brain Connectome. Our original goal was to obtain advanced neuroimaging (Diffusion Tensor Imaging and Resting-BOLD) in 140 SVR III participants and 100 healthy controls for brain connectome analyses. Linear regression and mediation statistical methods will be used to analyze associations of brain connectome measures with neurocognitive measures and clinical risk factors. Initial recruitment challenges occurred that were related to difficulties with: (1) coordinating brain MRI for participants already undergoing extensive testing in the parent study, and (2) recruiting healthy control subjects. The COVID-19 pandemic negatively affected enrollment late in the study. Enrollment challenges were addressed by: (1) adding additional study sites, (2) increasing the frequency of meetings with site coordinators, and (3) developing additional healthy control recruitment strategies, including using research registries and advertising the study to community-based groups. Technical challenges that emerged early in the study were related to the acquisition, harmonization, and transfer of neuroimages. These hurdles were successfully overcome with protocol modifications and frequent site visits that involved human and synthetic phantoms.

Single Ventricle Reconstruction III: Brain Connectome and Neurodevelopmental Outcomes: Design, Recruitment, and Technical Challenges of a Multicenter, Observational Neuroimaging Study

Patients with hypoplastic left heart syndrome who have been palliated with the Fontan procedure are at risk for adverse neurodevelopmental outcomes, lower quality of life, and reduced employability. We describe the methods (including quality assurance and quality control protocols) and challenges of a multi-center observational ancillary study, SVRIII (Single Ventricle Reconstruction Trial) Brain Connectome. Our original goal was to obtain advanced neuroimaging (Diffusion Tensor Imaging and Resting-BOLD) in 140 SVR III participants and 100 healthy controls for brain connectome analyses. Linear regression and mediation statistical methods will be used to analyze associations of brain connectome measures with neurocognitive measures and clinical risk factors. Initial recruitment challenges occurred related to difficulties with: 1) coordinating brain MRI for participants already undergoing extensive testing in the parent study, and 2) recruiting healthy control subjects. The COVID-19 pandemic negatively affected enrollment late in the study. Enrollment challenges were addressed by 1) adding additional study sites, 2) increasing the frequency of meetings with site coordinators and 3) developing additional healthy control recruitment strategies, including using research registries and advertising the study to community-based groups. Technical challenges that emerged early in the study were related to the acquisition, harmonization, and transfer of neuroimages. These hurdles were successfully overcome with protocol modifications and frequent site visits that involved human and synthetic phantoms.

Trial registration number

ClinicalTrials.gov Registration Number: NCT02692443.

Impaired Maternal-Fetal Environment and Risk for Preoperative Focal White Matter Injury in Neonates With Complex Congenital Heart Disease

Background Infants with congenital heart disease (CHD) are at risk for white matter injury (WMI) before neonatal heart surgery. Better knowledge of the causes of preoperative WMI may provide insights into interventions that improve neurodevelopmental outcomes in these patients. Methods and Results A prospective single-center study of preoperative WMI in neonates with CHD recorded data on primary cardiac diagnosis, maternal-fetal environment (MFE), delivery type, subject anthropometrics, and preoperative care. Total maturation score and WMI were assessed, and stepwise logistic regression modeling selected risk factors for WMI. Among subjects with severe CHD (n=183) who received a preoperative brain magnetic resonance imaging, WMI occurred in 40 (21.9%) patients. WMI prevalence (21.4%-22.1%) and mean volumes (119.7-160.4 mm3) were similar across CHD diagnoses. Stepwise logistic regression selected impaired MFE (odds ratio [OR], 2.85 [95% CI, 1.29-6.30]), male sex (OR, 2.27 [95% CI, 1.03-5.36]), and older age at surgery/magnetic resonance imaging (OR, 1.20 per day [95% CI, 1.03-1.41]) as risk factors for preoperative WMI and higher total maturation score values (OR, 0.65 per unit increase [95% CI, 0.43-0.95]) as protective. A quarter (24.6%; n=45) of subjects had ≥1 components of impaired MFE (gestational diabetes [n=12; 6.6%], gestational hypertension [n=11; 6.0%], preeclampsia [n=2; 1.1%], tobacco use [n=9; 4.9%], hypothyroidism [n=6; 3.3%], and other [n=16; 8.7%]). In a subset of 138 subjects, an exploratory analysis of additional MFE-related factors disclosed other potential risk factors for WMI. Conclusions This study is the first to identify impaired MFE as an important risk factor for preoperative WMI. Vulnerability to preoperative WMI was shared across CHD diagnoses.

Impact of cardiopulmonary bypass on cerebrovascular autoregulation assessed by ultrafast ultrasound imaging

Newborns with congenital heart disease undergoing cardiac surgery are at risk of neurodevelopmental impairment with limited understanding of the impact of intra-operative cardiopulmonary bypass (CPB), deep hypothermia and selective cerebral perfusion on the brain. We hypothesized that a novel ultrasound technique, ultrafast power Doppler (UPD), can assess variations of cerebral blood volume (CBV) in neonates undergoing cardiac surgery requiring CPB. UPD was performed before, during and after surgery in newborns with hypoplastic left heart syndrome undergoing a Norwood operation. We found that global CBV was not significantly different between patients and controls (P = 0.98) and between pre- and post-surgery (P = 0.62). UPD was able to monitor changes in CBV throughout surgery, revealing regional differences in CBV during hypothermia during which CBV correlated with CPB flow rate (R²  = 0.52, P = 0.021). Brain injury on post-operative magnetic resonance imaging was observed in patients with higher maximum variation in CBV. Our findings suggest that UPD can quantify global and regional brain perfusion variation during neonatal cardiac surgery with this first intra-operative application demonstrating an association between CBV and CPB flow rate, suggesting loss of autoregulation. Therefore, the measurement of CBV by UPD could enable optimization of cerebral perfusion during cardiac surgery in neonates. KEY POINTS: The impact of cardiopulmonary bypass (CPB) on the neonatal brain undergoing cardiac surgery is poorly understood. Ultrafast power Doppler (UPD) quantifies cerebral blood volume (CBV), a surrogate of brain perfusion. CBV varies throughout CPB surgery and is associated with variation of the bypass pump flow rate during deep hypothermia. Association between CBV and bypass pump flow rate suggests loss of cerebrovascular autoregulatory processes. Quantitative monitoring of cerebral perfusion by UPD could provide a direct parameter to optimize CPB flow rate.

Normothermic Versus Hypothermic Norwood Procedure

BACKGROUND

Either deep hypothermia with circulatory arrest or hypothermic perfusion with antegrade selective cerebral perfusion is used during the Norwood procedure for hypoplastic left heart syndrome. Normothermic perfusion has been described for pediatric patients. The aim of this study was to compare the early outcomes of patients undergoing the Norwood procedure with antegrade selective cerebral perfusion under hypothermia with the procedure under normothermia.

METHODS

From 2005 to 2020, 117 consecutive patients with hypoplastic left heart syndrome underwent the Norwood procedure: 68 (58.2%) under hypothermia and 49 (41.8%) under normothermia. Antegrade selective cerebral perfusion flow was adjusted to maintain right radial arterial pressure above 50 mm Hg, and a flow rate of 40 to 50 mL kg^-1 min^-1. Baseline characteristics, operative data, and postoperative outcomes including lactate recovery time were compared.

RESULTS

The baseline characteristics and cardiovascular diagnosis were similar in both groups. The normothermic group had a significantly shorter bypass time (in minutes) of 90.31 (±31.60) versus 123.63 (±25.33), a cross-clamp time of 45.24 (±16.35) versus 81.93 (±16.34), and an antegrade selective cerebral perfusion time of 25.61 (±13.84) versus 47.30 (±14.35) (P < .001). There were no statistically significant differences in the immediate postoperative course, or in terms of in-hospital mortality, which totaled 9 (18.4%) in the normothermic group, and 10 (14.9%) in the hypothermic group (P = .81).

CONCLUSION

The normothermic Norwood procedure with selective cerebral perfusion is feasible and safe in terms of in-hospital mortality and short-term outcomes. It is comparable to the standard hypothermic Norwood with selective cerebral perfusion.

Structural Brain Alterations and Their Associations With Function in Children, Adolescents, and Young Adults With Congenital Heart Disease

Most neonates who receive surgery for complex congenital heart disease (CHD) will survive well into adulthood, however, many of them will face functional challenges at one point during their life as a consequence of their atypical neurodevelopment. Recent advances in neuroscience and the increasing accessibility of magnetic resonance imaging have allowed numerous studies to identify the nature and extent of the brain alterations that are particular to survivors with CHD. Nevertheless, and considering that the range of outcomes is broad in this population, the functional consequences of these brain differences is not always evident. In this review, we summarize the present state of knowledge regarding the structure-function relationships evaluated in children, adolescents, and young adults with CHD using structural magnetic resonance imaging. Overall smaller total and regional brain volume, as well as lower fractional anisotropy in numerous brain regions, were frequently associated with lower cognitive outcomes including executive functioning and memory in adolescents and young adults with CHD. However, we identify several gaps in knowledge including the limited number of prospective investigations involving neonatal imaging and follow-up during childhood or adolescence, as well as the need for studies that evaluate a broader range of functional outcomes and not only the cognitive abilities. Future interdisciplinary investigations using multimodal imaging techniques could help address these gaps.

Declining Incidence of Postoperative Neonatal Brain Injury in Congenital Heart Disease

BACKGROUND

Brain injury is common in neonates with complex neonatal congenital heart disease (CHD) and affects neurodevelopmental outcomes.

OBJECTIVES

Given advancements in perioperative care, we sought to determine if the rate of preoperative and postoperative brain injury detected by using brain magnetic resonance imaging (MRI) and associated clinical risk factors have changed over time in complex CHD.

METHODS

A total of 270 term newborns with complex CHD were prospectively enrolled for preoperative and postoperative brain MRIs between 2001 and 2021 with a total of 466 MRI scans. Brain injuries in the form of white matter injury (WMI) or focal stroke and clinical factors were compared across 4 epochs of 5-year intervals with logistic regression.

RESULTS

Rates of preoperative WMI and stroke did not change over time. After adjusting for timing of the postoperative MRI, site, and cardiac group, the odds of newly acquired postoperative WMI were significantly lower in Epoch 4 compared with Epoch 1 (OR: 0.29; 95% CI: 0.09-1.00; P = 0.05). The adjusted probability of postoperative WMI declined significantly by 18.7% from Epoch 1 (24%) to Epoch 4 (6%). Among clinical risk factors, lowest systolic, mean, and diastolic blood pressures in the first 24 hours after surgery were significantly higher in the most recent epoch.

CONCLUSIONS

The prevalence of postoperative WMI has declined, whereas preoperative WMI rates remain constant. More robust postoperative blood pressures may explain these findings by minimizing periods of ischemia and supporting cerebral perfusion. These results suggest potential modifiable clinical targets in the postoperative time period to minimize the burden of WMI.

Impact of cardiac surgical timing on the neurodevelopmental outcomes of newborns with Complex congenital heart disease (CHD)

Background

More than half of infants with complex congenital heart disease (CHD) will have a neurodevelopmental disorder of multifactorial causes. The preoperative period represents a time-window during which neonates with complex CHD are in a state of hypoxia and hemodynamic instability, which fosters the emergence of brain injuries and, thus, affects early brain networks and neurodevelopmental outcomes. Currently, there is no consensus regarding the optimal age for cardiac surgery in terms of neurodevelopmental outcomes, and its definition is a real challenge. Our aim is to determine the relationship between cardiac surgical timing and long-term neurodevelopmental outcomes for various types of complex CHD.

Methods

We hypothesize that earlier surgical timing could represent a neuroprotective strategy that reduces perioperative white matter injuries (WMIs) and postoperative morbidity, leading to improved neurodevelopmental outcomes in infants with complex CHD. Firstly, our prospective study will allow us to determine the correlation between age at the time of surgery (days of life) and neurodevelopmental outcomes at 24 months. We will then analyze the correlation between age at surgery and (i) the incidence of WMIs (through pre- and postoperative MRIs), (ii) postoperative morbidity, and (iii) the duration of the hospital stay.

Implications and Dissemination

This research protocol was registered in the Clinical Trial Registry (National Clinical Trial: NCT04733378). This project aims to help launch the first Neurocardiac Investigation Clinic in Marseille - AP-HM - to propose an overall personalized monitoring and treatment program for patients operated on for complex CHD.

A guide to prenatal counseling regarding neurodevelopment in congenital heart disease

Advances in cardiac surgical techniques taking place over the past 50 years have resulted in the vast majority of children born with congenital cardiac malformations now surviving into adulthood. As the focus shifts from survival to the functional outcomes of our patients, it is increasingly being recognized that a significant proportion of patients undergoing infant cardiac repair experience adverse neurodevelopmental (ND) outcomes. The etiology of abnormal brain development in the setting of congenital heart disease is poorly understood, complex, and likely multifactorial. Furthermore, the efficacy of therapies available for the learning disabilities, attention deficit, and hyperactivity disorders and other ND deficits complicating congenital heart disease is currently uncertain. This situation presents a challenge for prenatal counseling as current antenatal testing does not usually provide prognostic information regarding the likely ND trajectories of individual patients. However, we believe it is important for parents to be informed about potential issues with child development when a new diagnosis of congenital heart disease is disclosed. Parents deserve a comprehensive and thoughtful approach to this subject, which conveys the uncertainties involved in predicting the severity of any developmental disorders encountered, while emphasizing the improvements in outcomes that have already been achieved in infants with congenital heart disease. A balanced approach to counseling should also discuss what local arrangements are in place for ND follow-up. This review presents an up-to-date overview of ND outcomes in patients with congenital heart disease, providing possible approaches to communicating this information to parents during prenatal counseling in a sensitive and accurate manner.

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.

A retrospective study of perioperative clinical seizures and epilepsy in children after operation for CHD

This study investigated the incidence and risk factors of perioperative clinical seizure and epilepsy in children after operation for CHD. We included 777 consecutive children who underwent operation from January 2013 to December 2016 at Kanagawa Children's Medical Center, Kanagawa, Japan. Perinatal, perioperative, and follow-up medical data were collected. Elastic net regression and mediation analysis were performed to investigate risk factors of perioperative clinical seizure and epilepsy. Anatomic CHD classification was performed based on the preoperative echocardiograms; cardiac surgery was evaluated using Risk Adjustment in Congenital Heart Surgery 1. Twenty-three (3.0%) and 15 (1.9%) patients experienced perioperative clinical seizure and epilepsy, respectively. Partial regression coefficient with epilepsy as the objective variable for anatomical CHD classification, Risk Adjustment in Congenital Heart Surgery 1, and the number of surgeries was 0.367, 0.014, and 0.142, respectively. The proportion of indirect effects on epilepsy via perioperative clinical seizure was 22.0, 21.0, and 33.0%, respectively. The 15 patients with epilepsy included eight cases with cerebral infarction, two cases with cerebral haemorrhage, and three cases with hypoxic-ischaemic encephalopathy; white matter integrity was not found. Anatomical complexity of CHD, high-risk cardiac surgery, and multiple cardiac surgeries were identified as potential risk factors for developing epilepsy, with a low rate of indirect involvement via perioperative clinical seizure and a high rate of direct involvement independently of perioperative clinical seizure. Unlike white matter integrity, stroke and hypoxic-ischaemic encephalopathy were identified as potential factors for developing epilepsy.

Age Difference of the Relationship Between Cerebral Oxygen Saturation and Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model

Recently, monitoring of cerebral oxygen saturation (ScO₂) has become widespread in pediatric cardiac surgery. Our previous study reported that mean blood pressure (mBP) was the major contributor to ScO₂ throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10 kg. We speculated that this result might be attributable to incomplete cerebral autoregulation in such young children. Accordingly, our hypothesis is that the relationship between ScO₂ and the physiological parameters may change according to the growth of the children. ScO₂ was measured with an INVOS 5100C (Somanetics, Troy, MI). Random-effects analysis was employed with ScO₂ as a dependent variable, and seven physiological parameters (mBP, central venous pressure, nasopharyngeal temperature, SaO₂, hematocrit, PaCO₂, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods by dividing the patients into two groups: infants (Infant Group) and children who were more than 1 year old (Child Group). The Infant and Child Groups consisted of 28 and 21 patients. In the random-effects analysis, mBP was the major contributor to ScO₂ during CPB in both groups. During the pre-CPB period, the effect of mBP was strongest in the Infant group. However, its effect was second to that of SaO₂ in the Child Group. During the post-CPB period, SaO₂ and mBP still affected ScO₂ in the Infant group. However, the dominant contributors were unclear in the Child Group. Cerebral autoregulation may be immature in infants. In addition, it may be impaired during CPB even after 1 year of age.

In infants with congenital heart disease autonomic dysfunction is associated with pre-operative brain injury

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.

Chronic hypoxemia induces mitochondrial respiratory complex gene expression in the fetal sheep brain

Objective

The molecular pathways underlying hypoxemia-induced alterations in neurodevelopment of infants with congenital heart disease have not been delineated. We used transcriptome analysis to investigate differential gene expression induced by hypoxemia in an ovine artificial-womb model.

Methods

Mid-gestation fetal sheep (median [interquartile range] 109 [107-112] days' gestation) were cannulated via the umbilical vessels, attached to a pumpless, low-resistance oxygenator circuit, and incubated in a sterile, fluid environment for 22 [21-23] days. Fetuses were maintained with an oxygen delivery of 20-25 mL/kg/min (normoxemia, n = 3) or 14-16 mL/kg/min (hypoxemia, n = 4). Transcriptional profiling by RNA sequencing was carried out on left frontal brains and hypoxemia-regulated genes were identified by differential gene expression analysis.

Results

A total of 228 genes whose expression was up or down regulated by ≥1.5-fold (false discovery rate ≤0.05) were identified. The majority of these genes were induced in hypoxemic animals compared to normoxemic controls, and functional enrichment analysis identified respiratory electron transport as a pathway strongly upregulated in the brain during chronic hypoxemia. Further examination of hypoxemia-induced genes showed robust induction of all 7 subunits of the mitochondrial NADH:ubiquinone oxidoreductase (complex I). Other hypoxemia-induced genes included cytochrome B, a component of complex III, and ATP6, ATP8, both of which are components of complex V.

Conclusions

Chronic fetal hypoxemia leads to upregulation of multiple mitochondrial respiratory complex genes critical for energy production and reactive oxygen species generation, including complex I. These data provide valuable insight into potential pathways involved in chronic hypoxemia-induced neuropathology and offers potential therapeutic targets for fetal neuroprotection in fetuses with congenital heart defects.

Language abilities in preschool children with critical CHD: a systematic review

CONTEXT

Children with critical CHD are at risk for neurodevelopmental impairments, including delays in expressive and receptive language development. However, no study has synthesised the literature regarding language abilities in children with this condition.

OBJECTIVE

We summarised the literature regarding expressive and receptive language in preschool children with critical CHD.

DATA SOURCES

MEDLINE, Embase, Scopus, Child Development and Adolescent Studies, ERIC, PsycINFO, and CINAHL.

STUDY SELECTION

We included studies published between January, 1990 and 1 July, 2021, focused on children aged ≤5 years with critical CHD requiring a complex cardiac procedure at age <1 year. Language ability was documented using standardised, validated tools assessing both expressive and receptive language outcomes.

DATA EXTRACTION

Data (study, patient and language characteristics, and results) were extracted by two reviewers.

RESULTS

Seventeen studies were included. Among children 2-5 years old with critical CHD, there were statistically significant deficits in overall (standardised mean difference: -0.46; 95 % confidence interval: -0.56, -0.35), expressive (standardised mean difference: -0.45;95 % confidence interval: -0.54, -0.37), and receptive (standardised mean difference: -0.32; 95 % confidence interval: -0.40, -0.23) language compared to normative data. Results reported as medians were similar to meta-analysis findings. Subgroup analysis showed that children with univentricular physiology had lower language scores than children with biventricular physiology.

CONCLUSIONS

Preschool children with critical CHD had statistically significantly lower language outcomes compared to expected population norms. Healthcare professionals should test early and often for language deficits, referring to individually tailored supports.

Evaluation of acute kidney injury after surgery for congenital heart disease in neonates: a tertiary hospital experience

PURPOSE OF THE ARTICLE

Acute kidney injury (AKI) after cardiac surgery in children with congenital heart disease (CHD) is a serious complication closely associated with high morbidity and mortality. Despite numerous studies on AKI in children, most studies have excluded neonates. We sought to characterize AKI associated with cardiac surgery in neonates, determine its incidence, perioperative and postoperative risk factors, and short-term results.

MATERIALS AND METHODS

This retrospective study included 177 neonates who were operated on for CHD in our hospital between January 2015 and December 2019. Data of the patients were analyzed according to nKDIGO (neonatal Kidney Disease Improving Global Outcomes) and nRIFLE (neonatal Risk, Injury, Failure, Loss of function, End-stage kidney disease) criteria for evaluating AKI retrospectively. Data of groups with and without AKI were analyzed.

RESULTS

The average age of 177 neonates were 8.2 ± 6.1 (1-28) days. Twenty-two (12.4%) neonates had CS-AKI defined according to nKDIGO criteria. Four (2.3%) neonates reached nKDIGO stage I, 1 (0.6%) reached stage II, 17 (9.6%) reached stage III. Thirty-eight (21.5%) neonates had CS-AKI defined according to nRIFLE criteria. Twenty-four (13.6%) neonates reached nRIFLE stage risk(R), 6 (3.4%) reached stage injury(I), 8 (4.5%) reached stage failure (F). The incidence of cardiac surgery-associated acute kidney injury (CS-AKI) in neonates was 12.5% and 21.5% for nKDIGO and nRIFLE, respectively. The percentage difference between nKDIGO and nRIFLE for AKI assessment was due to the criteria for nRIFLE stage risk(R) urine output < 1.5 mL/kg/h for 24 h. In both classifications, the duration of cardiopulmonary bypass, operation, inotropic treatment, and mechanical ventilation, length of intensive care unit (ICU), and hospital stay were significantly higher in the AKI group than those without AKI group (p˂.05). The mortality rate in the groups with AKI was found to be significantly higher (p˂.05) than in the groups without AKI. In Kappa analysis, when two classifications were compared according to AKI stages, a significant agreement was found between nKDIGO and nRIFLE classifications (p˂.05) (Kappa: 0.299).

CONCLUSION

AKI and mortality rates were similar between groups according to the nKDIGO and nRIFLE criteria. For early prediction of AKI and adverse outcomes, diagnostic reference intervals might be specified in more detail in neonates undergoing cardiac surgery for CHD.

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.