Increasing duration of deep hypothermic circulatory arrest is associated with an increased incidence of postoperative electroencephalographic seizures

Temperature and Neurologic Outcomes in Neonates Undergoing Cardiac Surgery: A Society of Thoracic Surgeons Study

BACKGROUND

There is significant variability in postoperative neurological injury rates in patients with congenital heart disease, with early injuries impacting long-term neurodevelopmental outcomes; therefore, there is an urgent need for identifying effective strategies to mitigate such injuries.

OBJECTIVES

This study aims to assess the association between nadir intraoperative temperature (NIT) and early neurological outcomes in neonates undergoing congenital heart surgery.

METHODS

Analyzing data from 24,345 neonatal cardiac operations from the Society for Thoracic Surgeons Congenital Heart Surgery Database between 2010 and 2019, NIT was assessed using a mixed-effect logistic regression model, targeting major neurological injury (stroke, seizure, or deficit at discharge) as a primary endpoint.

RESULTS

The study observed a shift from hypothermic circulatory arrest to cerebral perfusion with an increase in mean nadir temperature from 23.9 °C to 25.6 °C (P < 0.0001). Major neurological injury was noted in 4.9% of the cohort, with variations based on surgical procedure. After adjusting for risk, NIT was not significantly associated with major neurological injuries overall, but a lower NIT showed protective effects in the Norwood subgroup. Factors increasing the risk of major neurological injury included younger age at surgery, the Norwood procedure, longer cardiopulmonary bypass times, younger gestational age, presence of noncardiac abnormalities, and chromosomal anomalies.

CONCLUSIONS

Whereas neurological injuries are prevalent after neonatal cardiac surgery, current practices lean towards higher core temperatures. This trend is supported by the nonsignificant impact of NIT on neurological outcomes. However, lower NIT in the Norwood subgroup indicates that reduced temperatures may be beneficial amidst specific risk factors.

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.

Continuous Electroencephalogram (cEEG) Findings and Neurodevelopmental Outcomes in Neonates with Congenital Heart Disease (CHD) at 12-24 Months of Age

OBJECTIVE

This study aims to assess the role of continuous EEG (cEEG) background patterns and duration of cross-clamp time and cardiopulmonary bypass (CPB) in children with congenital heart disease (CHD) undergoing cardiac surgery and its correlation with abnormal neurodevelopmental outcomes at 12-24 months on Bayley Scales of Infant and Toddler Development (BSID-III).

METHODS

This retrospective cohort study included infants with CHD and cEEG monitoring, who underwent surgery by 44 weeks gestational age.

RESULTS

34 patients were included, who were operated at median age - 7 days. Longer duration of cross- camp time was associated with poor language composite scores (LCS) (p value = 0.036). A significant association existed between severity of encephalopathy in 24-hour post-operative period and poor LCS (p value = 0.026).

CONCLUSION

Majority of neonates with CHD have below average cognitive, language and motor composite scores on BSID-III. Longer duration of cross-clamp time and severity of encephalopathy during 24-hour post-operative EEG monitoring are associated with poor LCS.

Incidence of postoperative seizures in neonates following cardiac surgery with regional cerebral perfusion and deep hypothermic circulatory arrest

Objectives

Historically, our center has primarily used deep hypothermic circulatory arrest, but in recent years some surgeons have selectively used regional cerebral perfusion as an alternative. We aimed to compare the incidence of postoperative electroencephalographic seizure incidence in neonates undergoing surgery with regional cerebral perfusion and deep hypothermic circulatory arrest.

Methods

A retrospective analysis was performed in neonates who underwent surgery between 2012 and 2022 with either deep hypothermic circulatory arrest or regional cerebral perfusion with routine postoperative continuous electroencephalography monitoring for 48 hours. Propensity matching was performed to compare postoperative seizure risk between the 2 groups.

Results

Among 1136 neonates undergoing cardiac surgery with cardiopulmonary bypass, regional cerebral perfusion was performed in 99 (8.7%) and deep hypothermic circulatory arrest in 604 (53%). The median duration of regional cerebral perfusion was 49 minutes (interquartile range, 38-68) and deep hypothermic circulatory arrest was 41 minutes (interquartile range, 31-49). The regional cerebral perfusion group had significantly longer total support, cardiopulmonary bypass, and aortic crossclamp times. Overall seizure incidence was 11% (N = 76) and 13% (N = 35) in the most recent era (2019-2022). The unadjusted seizure incidence was similar in neonates undergoing regional cerebral perfusion (N = 12, 12%) and deep hypothermic circulatory arrest (N = 64, 11%). After propensity matching, the seizure incidence was similar in neonates undergoing regional cerebral perfusion (N = 12, 12%) and deep hypothermic circulatory arrest (N = 37, 12%) (odds ratio, 0.97; 95% CI, 0.55-1.71; P = .92).

Conclusions

In this contemporary single-center experience, the incorporation of regional cerebral perfusion did not result in a change in seizure incidence in comparison with deep hypothermic circulatory arrest. However, unmeasured confounders may have impacted these findings. Further studies are needed to determine the impact, if any, of regional cerebral perfusion on postoperative seizure incidence.

Electroencephalography as a tool to predict cerebral oxygen metabolism during deep-hypothermic circulatory arrest in neonates with critical congenital heart disease

Objectives

Recent research suggests that increased cerebral oxygen use during surgical intervention for neonates with congenital heart disease may play a role in the development of postoperative white matter injury. The objective of this study is to determine whether increased cerebral electrical activity correlates with greater decrease of cerebral oxygen saturation during deep hypothermic circulatory arrest.

Methods

Neonates with critical congenital heart disease requiring surgical intervention during the first week of life were studied. All subjects had continuous neuromonitoring with electroencephalography and an optical probe (to quantify cerebral oxygen saturation) during cardiac surgical repair that involved the use of cardiopulmonary bypass and deep hypothermic circulatory arrest. A simple linear regression was used to investigate the association between electroencephalography metrics before the deep hypothermic circulatory arrest period and the change in cerebral oxygen saturation during the deep hypothermic circulatory arrest period.

Results

Sixteen neonates had both neuromonitoring modalities attached during surgical repair. Cerebral oxygen saturation data from 5 subjects were excluded due to poor data quality, yielding a total sample of 11 neonates. A simple linear regression model found that the presence of electroencephalography activity at the end of cooling is positively associated with the decrease in cerebral oxygen saturation that occurs during deep hypothermic circulatory arrest (P < .05).

Conclusions

Electroencephalography characteristics within 5 minutes before the initiation of deep hypothermic circulatory arrest may be useful in predicting the decrease in cerebral oxygen saturation that occurs during deep hypothermic circulatory arrest. Electroencephalography may be an important tool for guiding cooling and the initiation of circulatory arrest to potentially decrease the prevalence of new white matter injury in neonates with critical congenital heart disease.

Differences in Quality of Life in Children Across the Spectrum of Congenital Heart Disease

OBJECTIVE

To create complexity groups based upon a patient's cardiac medical history and to test for group differences in health-related quality of life (HRQOL).

METHODS

Patients 8-18 years with congenital heart disease (CHD) and parent-proxies from the Pediatric Cardiac Quality of Life Inventory (PCQLI) Testing Study were included. Outcome variables included PCQLI Total, Disease Impact, and Psychosocial Impact scores. Using a patient's medical history (cardiac, neurologic, psychological, and cognitive diagnosis), latent class analysis (LCA) was used to create CHD complexity groups. Covariates included demographics and burden of illness (number of: school weeks missed, physician visits in the past year, and daily medications). Generalized estimation equations tested for differences in burden of illness and patient and parent-proxy PCQLI scores.

RESULTS

Using 1482 CHD patients (60% male; 84% white; age 12.3 ± 3.0 years), latent class analysis (LCA) estimates showed 4 distinct CHD complexity groups (Mild, Moderate 1, Moderate 2, and Severe). Increasing CHD complexity was associated with increased risk of learning disorders, seizures, mental health problems, and history of stroke. Greater CHD complexity was associated with greater burden of illness (P < .01) and lower patient- and parent-reported PCQLI scores (P < .001).

CONCLUSIONS

LCA identified 4 congenital heart disease (CHD) complexity groupings. Increasing CHD complexity was associated with higher burden of illness and worse patient- and parent-reported HRQOL.

A Narrative Review Illustrating the Clinical Utility of Electroencephalogram-Guided Anesthesia Care in Children

The major therapeutic end points of general anesthesia include hypnosis, amnesia, and immobility. There is a complex relationship between general anesthesia, responsiveness, hemodynamic stability, and reaction to noxious stimuli. This complexity is compounded in pediatric anesthesia, where clinicians manage children from a wide range of ages, developmental stages, and body sizes, with their concomitant differences in physiology and pharmacology. This renders anesthetic requirements difficult to predict based solely on a child's age, body weight, and vital signs. Electroencephalogram (EEG) monitoring provides a window into children's brain states and may be useful in guiding clinical anesthesia management. However, many clinicians are unfamiliar with EEG monitoring in children. Young children's EEGs differ substantially from those of older children and adults, and there is a lack of evidence-based guidance on how and when to use the EEG for anesthesia care in children. This narrative review begins by summarizing what is known about EEG monitoring in pediatric anesthesia care. A key knowledge gap in the literature relates to a lack of practical information illustrating the utility of the EEG in clinical management. To address this gap, this narrative review illustrates how the EEG spectrogram can be used to visualize, in real time, brain responses to anesthetic drugs in relation to hemodynamic stability, surgical stimulation, and other interventions such as cardiopulmonary bypass. This review discusses anesthetic management principles in a variety of clinical scenarios, including infants, children with altered conscious levels, children with atypical neurodevelopment, children with hemodynamic instability, children undergoing total intravenous anesthesia, and those undergoing cardiopulmonary bypass. Each scenario is accompanied by practical illustrations of how the EEG can be visualized to help titrate anesthetic dosage to avoid undersedation or oversedation when patients experience hypotension or other physiological challenges, when surgical stimulation increases, and when a child's anesthetic requirements are otherwise less predictable. Overall, this review illustrates how well-established clinical management principles in children can be significantly complemented by the addition of EEG monitoring, thus enabling personalized anesthesia care to enhance patient safety and experience.

Electroencephalographic changes in neurologically free patients with tetralogy of Fallot after surgical repair: a cross section study in Egyptian children

Background

Surgical correction of tetralogy of Fallot (TOF) is still one of the most frequently performed intervention in pediatric cardiac surgery. The occurrence of seizures after repair or palliation of congenital heart disease (CHD) is a marker for a central nervous system (CNS) injury and has been associated with adverse neurodevelopmental sequelae. The prognostic value of electroencephalogram (EEG) for outcome prediction is glowing in children with CHD undergoing open-heart surgery who are at risk for subsequent neurodevelopmental deficits. To our knowledge, this is the first study to detect the EEG changes in neurologically free TOF patients after surgical repair

Results

Our study included 68 TOF cases and 32 sex- and age-matched control group; they were 66.0% males and 34.0% females. The mean age of the studied children was 11.41 ± 4.23 years. There was statistically significant difference between TOF patients and control group as regards alpha power and Delta% in left occipital region and Alpha% in right occipital region, with dominant alpha waves in patients’ right occipital region. None of our patients had epileptic waves. The duration after operation showed negative correlation with Delta% at left occipital region and positive correlation with Alpha% in right occipital region (p = 0.002, p = 0.044 respectively).

Conclusion

TOF cases showed changes in EEG parameters chiefly dominant alpha power and Delta% in left occipital region and dominant Alpha% in right occipital region. Duration after surgery correlated negatively with Delta% at left occipital region, and positively with Alpha% in the right occipital region. Subsequent assessment is recommended to study long-term hazards of these varied dominance of EEG waves in our patients, e.g., evaluation of the cognitive functions.

Continuous electroencephalography (cEEG) in infants with congenital heart disease (CHD)

BACKGROUND

Neonates with congenital heart disease (CHD) undergoing cardiopulmonary bypass (CPB) surgery have increased risk of impaired neurodevelopmental outcomes secondary to brain injury. This study aims to characterize pre- and post-operative continuous EEG (cEEG) patterns to detect abnormal cerebral activity in infants with CHD and investigate whether an association exists between the degree of encephalopathy in pre- and post-operative cEEG.

METHODS

This retrospective cohort study conducted between 2010 and 2018 at a tertiary hospital in Cleveland, OH included infants with CHD with cEEG monitoring, who underwent CPB surgery within first 6 months of life.

RESULTS

Study included 77 patients, of which 61% were males who were operated at median age 6 days. Pre-operatively, 69% and 87% had normal cEEG and sleep-wake cycles, respectively. Post-operatively, 80% had abnormal cEEG. Longer circulatory arrest time and CPB were associated with lack of continuity (p 0.011), excessive discontinuity (p 0.007) and prolonged inter-burst interval (IBI) duration (p value < 0.001). A significant association existed between severity of encephalopathy in immediate and 24-h post-operative period (p value < 0.001).

CONCLUSIONS

More than 80% of neonates with CHD have abnormal post-operative EEG. Longer circulatory arrest time and CPB were associated with lack of continuity, excessive discontinuity, and prolonged IBI duration on post-operative EEG.

IMPACT

This study shows that majority of neonates with congenital heart disease (CHD) have normal pre-operative EEG with a continuous background and normal sleep-wake cycles. Also, 80% of neonates had abnormal post-operative EEG. Longer duration of arrest time and bypass time was associated with lack of continuity, excessive discontinuity, and prolonged IBI duration during post-operative EEG monitoring. These findings will help clinicians when counseling parents in the intensive care unit, risk stratification, and long-term neurodevelopmental monitoring in these high-risk patients.

Pediatric Intensive Care Unit Patients: Sedation, Monitoring, and Neurodevelopmental Outcomes

The design and conduct of pediatric sedation studies in critically ill patients have historically been challenging due to the complexity of the pediatric intensive care unit (PICU) environment and the difficulty of establishing equipoise. Clinical trials, for instance, represent 1 important means of advancing our knowledge in this field, but there is a paucity of such studies in the literature. Accounting for ground-level factors in planning for each trial phase (eg, enrollment, intervention, assessment, and follow-up) and the presence of broader system limitations is of key importance. In addition, there is a need for early planning, coordination, and obtaining buy-in from individual study sites and staff to ensure success, particularly for multicenter studies. This review synthesizes the current state of pediatric sedation research and the myriad of challenges in designing and conducting successful trials in this particular area. The review poses consideration for future research directions, including novel study designs, and discusses electroencephalography monitoring and neurodevelopmental outcomes of PICU survivors.

Optimizing Neurodevelopmental Outcomes in Neonates With Congenital Heart Disease

Neurodevelopmental impairment is a common and important long-term morbidity among infants with congenital heart disease (CHD). More than half of those with complex CHD will demonstrate some form of neurodevelopmental, neurocognitive, and/or psychosocial dysfunction requiring specialized care and impacting long-term quality of life. Preventing brain injury and treating long-term neurologic sequelae in this high-risk clinical population is imperative for improving neurodevelopmental and psychosocial outcomes. Thus, cardiac neurodevelopmental care is now at the forefront of clinical and research efforts. Initial research primarily focused on neurocritical care and operative strategies to mitigate brain injury. As the field has evolved, investigations have shifted to understanding the prenatal, genetic, and environmental contributions to impaired neurodevelopment. This article summarizes the recent literature detailing the brain abnormalities affecting neurodevelopment in children with CHD, the impact of genetics on neurodevelopmental outcomes, and the best practices for neonatal neurocritical care, focusing on developmental care and parental support as new areas of importance. A framework is also provided for the infrastructure and resources needed to support CHD families across the continuum of care settings.

Perioperative electroencephalography in cardiac surgery with hypothermic circulatory arrest: a narrative review

OBJECTIVES

Cardiac surgery with hypothermic circulatory arrest (HCA) is associated with neurological morbidity of variable severity and electroencephalography (EEG) is a sensitive proxy measure of brain injury. We conducted a narrative review of the literature to evaluate the role of perioperative EEG monitoring in cardiac surgery involving HCA.

METHODS

Medline, Embase, Central and LILACS databases were searched to identify studies utilizing perioperative EEG during surgery with HCA in all age groups, published since 1985 in any language. We aimed to compare EEG use with no use but due to the lack of comparative studies, we performed a narrative review of its utility. Two or more reviewers independently screened studies for eligibility and extracted data.

RESULTS

Fourty single-centre studies with a total of 3287 patients undergoing surgery were identified. Most were observational cohort studies (34, 85%) with only 1 directly comparing EEG use with no use. EEG continuity (18, 45%), seizures (15, 38%) and electrocerebral inactivity prior to circulatory arrest (15, 38%) were used to detect, monitor, prevent and prognose neurological injury. Neurological dysfunction was reported in almost all studies and occurred in 0-21% of patients. However, the heterogeneity of reported clinical and EEG outcome measures prevented meta-analysis.

CONCLUSIONS

EEG is used to detect cortical ischaemia and seizures and predict neurological abnormalities and may guide intraoperative cerebral protection. However, there is a lack of comparative data demonstrating the benefit of perioperative EEG monitoring. Use of a standardized methodology for performing EEG and reporting outcome metrics would facilitate the conduct of high-quality clinical trials.

Incidence and predictors of epilepsy in children with congenital heart disease

OBJECTIVE

Children with CHD may be at increased risk for epilepsy. While the incidence of perioperative seizures after surgical repair of CHD has been well-described, the incidence of epilepsy is less well-defined. We aim to determine the incidence and predictors of epilepsy in patients with CHD.

METHODS

Retrospective cohort study of patients with CHD who underwent cardiopulmonary bypass at <2 years of age between January, 2012 and December, 2013 and had at least 2 years of follow-up. Clinical variables were extracted from a cardiac surgery database and hospital records. Seizures were defined as acute if they occurred within 7 days after an inciting event. Epilepsy was defined based on the International League Against Epilepsy criteria.

RESULTS

Two-hundred and twenty-one patients were identified, 157 of whom were included in our analysis. Five patients (3.2%) developed epilepsy. Acute seizures occurred in 12 (7.7%) patients, only one of whom developed epilepsy. Predictors of epilepsy included an earlier gestational age, a lower birth weight, a greater number of cardiac surgeries, a need for extracorporeal membrane oxygenation or a left ventricular assist device, arterial ischaemic stroke, and a longer hospital length of stay.

CONCLUSIONS

Epilepsy in children with CHD is rare. The mechanism of epileptogenesis in these patients may be the result of a complex interaction of patient-specific factors, some of which may be present even before surgery. Larger long-term follow-up studies are needed to identify risk factors associated with epilepsy in these patients.

Outcomes After Stage I Norwood Palliation in a Recently Established Program Can Achieve Results Similar to Longer Established Services

BACKGROUND

Infants with hypoplastic left heart syndrome (HLHS) or similar single ventricle cardiac lesions require a three-stage surgical approach, the first step being the Stage I Norwood procedure. The Queensland Children's Hospital (QCH) in Australia is a tertiary hospital providing the only cardiac surgical service to children in Queensland and northern New South Wales.

OBJECTIVE

To review the centre's outcomes of Norwood procedures performed in the last 6 years.

MATERIALS AND METHODS

We retrospectively evaluated all infants undergoing the stage I Norwood procedure between January 2015 and August 2021. Mortality, intensive care length of stay, events of cardiac arrest following surgery and duration of mechanical ventilation were calculated and analysed for subgroups depending on type of pulmonary shunt type (right-ventricle-to-pulmonary-artery shunt [RVPAS] vs the modified Blalock-Taussig shunt [MBTS]).

RESULTS

Forty-nine (49) patients were included. Overall survival to stage two operation (Glenn) was 90%. Both shunts were used evenly with the RVPA conduit preferred for HLHS and the MBTS largely chosen for hypoplastic left heart variants. In univariable analysis there was no difference in cardiac arrest or mortality rate for the patient with a RVPAS compared to the patient with a MBTS.

CONCLUSION

We show that a recently established Norwood program can achieve results that are comparable to those reported by longer established centres, and the international literature.

Retrospective Evaluation of First-line Levetiracetam use for Neonatal Seizures after Congenital Heart Defect repair with or without Extracorporeal Membrane Oxygenation

OBJECTIVE

Levetiracetam (LEV) efficacy for neonatal seizures is debated. We evaluated LEV as a first line anti-seizure medicine (ASM) in neonates following neonatal congenital heart defect (CHD) repair who did not require extracorporeal membrane oxygenation (ECMO) vs neonates who required ECMO.

METHODS

A single center retrospective review of neonates with CHD from 2015 to 2020 was conducted. Neonates were included if seizures were present on continuous EEG after CHD repair either on or off ECMO, and they received LEV as a first line ASM. Primary outcomes were seizure resolution with LEV, adverse events and response to subsequent ASM.

RESULTS

Eighteen total neonates were evaluated, 10 with seizures post-CHD repair who did not require ECMO and 8 who required ECMO. In the non-ECMO cohort, nine of ten were successfully treated with LEV monotherapy with no adverse events. In comparison, the eight neonates who required ECMO had a higher initial seizure burden (1.6% vs 17%, p=0.003), were more likely to have injury on neuroimaging (12.5 vs 75%, p= 0.04), and all neonates required multiple ASMs. Seizure burden did not decrease with LEV, but significantly decreased with phenobarbital and fosphenytoin (14.4% and 10.5%, p = 0.024).

CONCLUSIONS

Neonates with CHD and seizures on and off ECMO demonstrated divergent seizure characteristics including seizure burden and response to LEV. LEV may reduce neonatal seizure burden after uncomplicated CHD repair. However, in neonates requiring ECMO, multiple ASMs were required. A prospective evaluation of ASM efficacy and safety in this high-risk population is urgently needed.

Evaluation of Seizure Risk in Infants After Cardiopulmonary Bypass in the Absence of Deep Hypothermic Cardiac Arrest

Background

Guidelines recommend evaluation for electrographic seizures in neonates and children at risk, including after cardiopulmonary bypass (CPB). Although initial research using screening electroencephalograms (EEGs) in infants after CPB found a 21% seizure incidence, more recent work reports seizure incidences ranging 3–12%. Deep hypothermic cardiac arrest was associated with increased seizure risk in prior reports but is uncommon at our institution and less widely used in contemporary practice. This study seeks to establish the incidence of seizures among infants following CPB in the absence of deep hypothermic cardiac arrest and to identify additional risk factors for seizures via a prediction model.

Methods

A retrospective chart review was completed of all consecutive infants ≤ 3 months who received screening EEG following CPB at a single center within a 2-year period during 2017–2019. Clinical and laboratory data were collected from the perioperative period. A prediction model for seizure risk was fit using a random forest algorithm, and receiver operator characteristics were assessed to classify predictions. Fisher’s exact test and the logrank test were used to evaluate associations between clinical outcomes and EEG seizures.

Results

A total of 112 infants were included. Seizure incidence was 10.7%. Median time to first seizure was 28.1 h (interquartile range 18.9–32.2 h). The most important factors in predicting seizure risk from the random forest analysis included postoperative neuromuscular blockade, prematurity, delayed sternal closure, bypass time, and critical illness preoperatively. When variables captured during the EEG recording were included, abnormal postoperative neuroimaging and peak lactate were also highly predictive. Overall model accuracy was 90.2%; accounting for class imbalance, the model had excellent sensitivity and specificity (1.00 and 0.89, respectively).

Conclusions

Seizure incidence was similar to recent estimates even in the absence of deep hypothermic cardiac arrest. By employing random forest analysis, we were able to identify novel risk factors for postoperative seizure in this population and generate a robust model of seizure risk. Further work to validate our model in an external population is needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01313-1.

The role of diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy in monitoring cerebral hemodynamics during hypothermic circulatory arrests

OBJECTIVES

Real-time noninvasive monitoring of cerebral blood flow (CBF) during surgery is key to reducing mortality rates associated with adult cardiac surgeries requiring hypothermic circulatory arrest (HCA). We explored a method to monitor cerebral blood flow during different brain protection techniques using diffuse correlation spectroscopy (DCS), a noninvasive optical technique which, combined with frequency-domain near-infrared spectroscopy (FDNIRS), also provides a measure of oxygen metabolism.

METHODS

We used DCS in combination with FDNIRS to simultaneously measure hemoglobin oxygen saturation (SO2), an index of cerebral blood flow (CBFi), and an index of cerebral metabolic rate of oxygen (CMRO2i) in 12 patients undergoing cardiac surgery with HCA.

RESULTS

Our measurements revealed that a negligible amount of blood is delivered to the cerebral cortex during HCA with retrograde cerebral perfusion, indistinguishable from HCA-only cases (median CBFi drops of 93% and 95%, respectively) with consequent similar decreases in SO2 (mean decrease of 0.6 ± 0.1% and 0.9 ± 0.2% per minute, respectively); CBFi and SO2 are mostly maintained with antegrade cerebral perfusion; the relationship of CMRO2i to temperature is given by CMRO2i = 0.052e0.079T.

CONCLUSIONS

FDNIRS-DCS is able to detect changes in CBFi, SO2, and CMRO2i with intervention and can become a valuable tool for optimizing cerebral protection during HCA.

Deep hypothermic circulatory arrest in cyanotic piglets is associated with increased neuronal necrosis

BACKGROUND

The contribution of neonatal cyanosis, inherent to cyanotic congenital heart disease, to the magnitude of neurologic injury during deep hypothermic circulatory arrest has not been fully delineated. This study investigates the impact of cyanosis and deep hypothermic circulatory arrest on brain injury.

METHODS

Neonatal piglets were randomised to placement of a pulmonary artery to left atrium shunt to create cyanosis or sham thoracotomy. At day 7, animals were randomised to undergo deep hypothermic circulatory arrest or sham. Arterial oxygen tension and haematocrit were obtained. Neurobehavioural performance was serially assessed. The animals were sacrificed on day 14. Brain tissue was assessed for neuronal necrosis using a 5-point histopathologic score.

RESULTS

Four experimental groups were analysed (sham, n = 10; sham + deep hypothermic circulatory arrest, n = 8; shunt, n = 9; shunt + deep hypothermic circulatory arrest, n = 7). Cyanotic piglets had significantly higher haematocrit and lower partial pressure of oxygen at day 14 than non-cyanotic piglets. There were no statistically significant differences in neurobehavioural scores at day 1. However, shunt + deep hypothermic circulatory arrest piglets had evidence of greater neuronal injury than sham animals (median (range): 2 (0-4) versus 0 (0-0), p = 0.02).

DISCUSSION

Cyanotic piglets undergoing deep hypothermic circulatory arrest had increased neuronal injury compared to sham animals. Significant injury was not seen for either cyanosis or deep hypothermic circulatory arrest alone relative to shams. These findings suggest an interaction between cyanosis and deep hypothermic circulatory arrest and may partially explain the suboptimal neurologic outcomes seen in children with cyanotic heart disease who undergo deep hypothermic circulatory arrest.

Seizures Are Associated With Brain Injury in Infants Undergoing Extracorporeal Membrane Oxygenation

OBJECTIVE

Determine seizure frequency and association with neurologic outcomes in infants undergoing extracorporeal membrane oxygenation. Identify patient or clinical factors associated with seizures or brain injury on imaging.

METHODS

Retrospective, single-center study including infants less than 1 year of age, who underwent extracorporeal membrane oxygenation between 2012 and 2017.

RESULTS

A total of 104 infants met study criteria including 45 patients with continuous electroencephalographic (EEG) monitoring during their extracorporeal membrane oxygenation run and 59 infants without EEG. Seizures (electrographic-only or electro-clinical) were identified in 18 of the 45 (40%). Among the 18 infants with seizures, 14 (78%) had moderate to severe brain injury, whereas only 44% of those without seizures (12 of 27) on EEG had moderate to severe brain injury (P = .03). Cardiopulmonary resuscitation prior to extracorporeal membrane oxygenation (ECPR), mode of extracorporeal membrane oxygenation, length of stay, survival to discharge, and congenital heart disease were not associated with seizures. One of 10 patients with cyanotic congenital heart disease due to hypoplastic left heart syndrome had seizures compared with 7 of 10 patients with non-hypoplastic left heart syndrome lesions (P = .02). Seizures were associated with moderate to severe brain injury, after adjusting for ECPR and congenital heart disease (P = .04).

CONCLUSIONS

Electrographic seizures were common in patients undergoing extracorporeal membrane oxygenation and higher than previously reported. Seizures were associated with moderate to severe abnormalities on imaging, after adjusting for ECPR and congenital heart disease. This study adds to recent literature describing the risk of seizures in patients on extracorporeal membrane oxygenation and highlights the presence of brain injuries that may be identified by routine EEG surveillance.

Deep Hypothermic Circulatory Arrest in the Pediatric Population Undergoing Cardiac Surgery With Electroencephalography Monitoring: A Systematic Review and Meta-Analysis

OBJECTIVE

Cardiac surgery for repair of congenital heart defects poses unique hazards to the developing brain. Deep hypothermic circulatory arrest (DHCA) is a simple and effective method for facilitating a bloodless surgical field during congenital heart defect repair. There are, however, some concerns that prolonged DHCA increases the risk of nervous system injury. The electroencephalogram (EEG) is used in adult and, to a lesser extent, pediatric cardiac procedures as a neuromonitoring method. The present study was performed to assess outcomes following DHCA with EEG monitoring in the pediatric population.

DESIGN

In this systematic review and meta-analysis, the PubMed, Cochrane Central Register of Controlled Trials, Scopus, Institute of Science Index, and Embase databases were searched from inception for relevant articles. A fixed- or random-effects model, as appropriate, was used.

SETTING

Surgical setting.

PARTICIPANTS

Pediatric population (≤18 y old).

INTERVENTIONS

DHCA (18°C) with EEG monitoring.

MEASUREMENTS AND MAIN RESULTS

Nineteen articles with 1,267 pediatric patients ≤18 years were included. The event rate of clinical and EEG seizures among patients who underwent DHCA was 12.9% and 14.9%, respectively. Mortality was found to have a 6.3% prevalence. A longer duration of DHCA was associated with a higher risk of EEG seizure and neurologic abnormalities. In addition, seizures were associated with increased neurologic abnormalities and neurodevelopmental delay.

CONCLUSIONS

EEG and neurologic abnormalities were common after DHCA. A longer duration of DHCA was found to lead to more EEG seizure and neurologic abnormalities. Moreover, EEG seizures were more common than clinical seizures. Seizures were found to be associated with increased neurologic abnormalities and neurodevelopmental delay.

Total circulatory arrest as a support modality in congenital heart surgery: review and current evidence

The use of total circulatory arrest (TCA)/deep hypothermic circulatory arrest (DHCA) as a support modality in congenital heart surgery is a time-tested strategy. However, with technological advances, the widespread use of this technique has decreased. Adjunctive cerebral perfusion with continuous cardiopulmonary bypass (CPB) gradually has become more popular with a view to reduce the complications related to DHCA. In addition, better neuromonitoring and neuroprotective strategies have made DHCA much safer. However, the level of evidence to support the best way to protect the brain during congenital heart surgery is insufficient. This review analyzes the history, physiology, techniques of DHCA, as well as other alternative strategies like selective cerebral perfusion and presents the current available evidence.

Development and Validation of a Seizure Prediction Model in Neonates After Cardiac Surgery

BACKGROUND

Electroencephalographic seizures (ESs) after neonatal cardiac surgery are often subclinical and have been associated with poor outcomes. An accurate ES prediction model could allow targeted continuous electroencephalographic monitoring (CEEG) for high-risk neonates.

METHODS

ES prediction models were developed and validated in a multicenter prospective cohort where all postoperative neonates who underwent cardiopulmonary bypass (CPB) also underwent CEEG.

RESULTS

ESs occurred in 7.4% of neonates (78 of 1053). Model predictors included gestational age, head circumference, single-ventricle defect, deep hypothermic circulatory arrest duration, cardiac arrest, nitric oxide, extracorporeal membrane oxygenation, and delayed sternal closure. The model performed well in the derivation cohort (c-statistic, 0.77; Hosmer-Lemeshow, P = .56), with a net benefit (NB) over monitoring all and none over a threshold probability of 2% in decision curve analysis (DCA). The model had good calibration in the validation cohort (Hosmer-Lemeshow, P = .60); however, discrimination was poor (c-statistic, 0.61), and in DCA there was no NB of the prediction model between the threshold probabilities of 8% and 18%. By using a cut point that emphasized negative predictive value in the derivation cohort, 32% (236 of 737) of neonates would not undergo CEEG, including 3.5% (2 of 58) of neonates with ESs (negative predictive value, 99%; sensitivity, 97%).

CONCLUSIONS

In this large prospective cohort, a prediction model of ESs in neonates after CPB had good performance in the derivation cohort, with an NB in DCA. However, performance in the validation cohort was weak, with poor discrimination, poor calibration, and no NB in DCA. These findings support CEEG of all neonates after CPB.

Effect of perioperative amplitude-integrated electroencephalography on neurodevelopmental outcomes following infant heart surgery

The purpose of the current study was to determine the effect of perioperative amplitude-integrated electroencephalography (aEEG) on neurodevelopmental outcomes in infants with congenital heart disease (CHD). A total of 93 children with CHD were included in the current study. All patients enrolled in the present study had undergone cardiac surgery prior to 3 months of age and pre- or postoperative aEEG was monitored. Participants were assessed after 1 year using the Bayley Scales of Infant Test. A total of 82.2% of infants exhibited continuous normal voltage preoperatively (CNV) and 93.7% exhibited CNV postoperatively. Seizures were indicated in 2 infants preoperatively and 3 infants postoperatively. Compared with infants with PDI, infants with cyanotic CHD (β=17.218) exhibited a significantly lower MDI, an increased length of intensive care stay, and lower PDI scores (β=-0.577). Infants that underwent surgery with CPB exhibited higher PDI scores (β=11.956). Infants that exhibited behavioral problems also had lower PDI scores (β=-10.605). An abnormal preoperative background pattern and an absent postoperative SWC independently predicted poorer motor (P=0.014) and cognitive (P=0.049) outcomes at 1 year. The current study demonstrated that infants with CHD who underwent cardiac surgery prior to 3 months of age exhibited delayed neurodevelopmental outcomes, and that an aEEG assessment can aid in predicting these outcomes following surgery.

A retrospective comparison of phenobarbital and levetiracetam for the treatment of seizures following cardiac surgery in neonates

OBJECTIVE

To compare the safety and efficacy of phenobarbital and levetiracetam in a cohort of neonates with seizures following cardiac surgery.

METHODS

We performed a retrospective single-center study of consecutive neonates with electrographically confirmed seizures managed with antiseizure medication after cardiac surgery from June 15, 2012 to December 31, 2018. We compared the safety and efficacy of phenobarbital and levetiracetam as first-line therapy.

RESULTS

First-line therapy was phenobarbital in 31 neonates and levetiracetam in 22 neonates. Phenobarbital was associated with more adverse events (P = .006). Eight neonates (14%) experienced an adverse event related to phenobarbital use, including seven with hypotension and one with respiratory depression. No adverse events were reported with levetiracetam use. The cessation of electrographic seizures was similar in both groups, including 18 neonates (58%) with seizure cessation after phenobarbital and 12 neonates (55%) with seizure cessation after levetiracetam (P = 1.0). The combined cessation rates of phenobarbital and levetiracetam when used as first- or second-line therapy were 58% and 47%, respectively (P = .47).

SIGNIFICANCE

Phenobarbital was associated with more adverse events than levetiracetam, and the two drugs were equally but incompletely effective in treating electrographically confirmed seizures in neonates following cardiac surgery. Given its more acceptable safety profile and potential noninferiority, levetiracetam may be a reasonable option for first-line therapy for treatment of seizures in this population. Further prospective studies are needed to confirm these results.

Non-invasive optical neuromonitoring of the temperature-dependence of cerebral oxygen metabolism during deep hypothermic cardiopulmonary bypass in neonatal swine

Management of deep hypothermic (DH) cardiopulmonary bypass (CPB), a critical neuroprotective strategy, currently relies on non-invasive temperature to guide cerebral metabolic suppression during complex cardiac surgery in neonates. Considerable inter-subject variability in temperature response and residual metabolism may contribute to the persisting risk for postoperative neurological injury. To characterize and mitigate this variability, we assess the sufficiency of conventional nasopharyngeal temperature (NPT) guidance, and in the process, validate combined non-invasive frequency-domain diffuse optical spectroscopy (FD-DOS) and diffuse correlation spectroscopy (DCS) for direct measurement of cerebral metabolic rate of oxygen (CMRO₂). During CPB, n = 8 neonatal swine underwent cooling from normothermia to 18℃, sustained DH perfusion for 40 min, and then rewarming to simulate cardiac surgery. Continuous non-invasive and invasive measurements of intracranial temperature (ICT) and CMRO₂ were acquired. Significant hysteresis (p < 0.001) between cooling and rewarming periods in the NPT versus ICT and NPT versus CMRO₂ relationships were found. Resolution of this hysteresis in the ICT versus CMRO₂ relationship identified a crucial insufficiency of conventional NPT guidance. Non-invasive CMRO₂ temperature coefficients with respect to NPT (Q₁₀ = 2.0) and ICT (Q₁₀ = 2.5) are consistent with previous reports and provide further validation of FD-DOS/DCS CMRO₂ monitoring during DH CPB to optimize management.

The probability of seizures during continuous EEG monitoring in high-risk neonates

OBJECTIVE

We evaluated the impact of monitoring indication, early electroencephalography (EEG), and clinical features on seizure risk in all neonates undergoing continuous EEG (cEEG) monitoring following a standardized monitoring protocol.

METHODS

All cEEGs from unique neonates 34-48 weeks postmenstrual age monitored from 1/2011-10/2017 (n = 291) were included. We evaluated the impact of cEEG monitoring indication (acute neonatal encephalopathy [ANE], suspicious clinical events [SCEs], or other high-risk conditions [OHRs]), age, medication status, and early EEG abnormalities (including the presence of epileptiform discharges and abnormal background continuity, amplitude, asymmetry, asynchrony, excessive sharp transients, and burst suppression) on time to first seizure and overall seizure risk using Kaplan-Meier survival curves and multivariable Cox proportional hazards models.

RESULTS

Seizures occurred in 28% of high-risk neonates. Discontinuation of monitoring after 24 hours of seizure-freedom would have missed 8.5% of neonates with seizures. Overall seizure risk was lower in neonates monitored for ANE compared to OHR (P = .004) and trended lower compared to SCE (P = .097). The time course of seizure presentation varied by group, where the probability of future seizure was less than 1% after 17 hours of seizure-free monitoring in the SCE group, but required 42 hours in the OHR group, and 73 hours in the ANE group. The presence of early epileptiform discharges increased seizure risk in each group (ANE: adjusted hazard ratio [aHR] 4.32, 95% confidence interval [CI] 1.23-15.13, P = .022; SCE: aHR 10.95, 95% CI 4.77-25.14, P < 1e-07; OHR: aHR 56.90, 95% CI 10.32-313.72, P < 1e-05).

SIGNIFICANCE

Neonates who undergo cEEG are at high risk for seizures, and risk varies by monitoring indication and early EEG findings. Seizures are captured in nearly all neonates undergoing monitoring for SCE within 24 hours of cEEG monitoring. Neonates monitored for OHR and ANE can present with delayed seizures and require longer durations of monitoring. Early epileptiform discharges are the best early EEG feature to predict seizure risk.

Neurodevelopmental Outcomes Among Children With Congenital Heart Disease: At-Risk Populations and Modifiable Risk Factors

As survivable outcomes among patients with complex congenital heart disease (cCHD) have continued to improve over the last several decades, more attention is being dedicated to interventions that impact not just survival but quality of life among patients with cCHD. In particular, patients with cCHD are at risk for impaired neurodevelopmental outcomes. In this review summarizing select presentations given at the 14th Annual Pediatric Cardiac Intensive Care Society's Annual Meeting in 2019, we discuss the neurodevelopmental phenotype of patients with cCHD, patients at greatest risk of impaired development, and three specific modifiable risk factors impacting development.

Neurodevelopmental outcomes of children with congenital heart disease: A review

Congenital heart defects are the most common birth anomaly affecting approximately 1% of births. With improved survival in this population, there is enhanced ability to assess long-term morbidities including neurodevelopment. There is a wide range of congenital heart defects, from those with minimal physiologic consequence that do not require medical or surgical intervention, to complex structural anomalies requiring highly specialized medical management and intricate surgical repair or palliation. The impact of congenital heart disease on neurodevelopment is multifactorial. Susceptibility for adverse neurodevelopment increases with advancing severity of the defect with initial risk factors originating during gestation. Complex structural heart anomalies may pre-dispose the fetus to abnormal circulatory patterns in utero that ultimately impact delivery of oxygen rich blood to the fetal brain. Thus, the brain of a neonate born with complex congenital heart disease may be particularly vulnerable from the outset. That vulnerability is compounded during the newborn period and through childhood, as this population endures a myriad of medical and surgical interventions. For each individual patient, these factors are likely cumulative and synergistic with progression from fetal life through childhood. This review discusses the spectrum of risk factors that may impact neurodevelopment in children with congenital heart disease, describes current recommendations and practices for neurodevelopmental follow-up of children with congenital heart disease and reviews important neurodevelopmental trends in this high risk population.

School-Age Developmental and Educational Outcomes Following Cardiac Procedures in the First Year of Life: A Population-Based Record Linkage Study

The purpose of the study was to evaluate school-age developmental and educational outcomes for children with and without a cardiac procedure in the first year of life to improve understanding of longer-term neurodevelopmental outcomes in children who have had a cardiac procedure for congenital heart disease, the most common serious congenital anomaly. A population-based cohort study using record linkage of state-wide data was undertaken, evaluating children born in New South Wales, Australia, 2001-2007. Those with and without a cardiac procedure in the first year of life with a linked developmental (Australian version Early Development Instrument testing result, age 4-6 years) and/or educational outcome (Australian National Assessment Program result, age 7-9 years) were included. Perinatal, perioperative and sociodemographic factors were examined using multivariable logistic regression models. Of 468,329 eligible children, 768 had a cardiac procedure in the first year of life and 582 were included. For those with a cardiac procedure and developmental outcome (n = 260), 13.1% were classified as having 'special needs' compared to 4.4% without a cardiac procedure. Of those with an educational outcome, after adjusting for perinatal, perioperative and demographic variables, children with a cardiac procedure (n = 396) were twice as likely to score below National Minimum Standard in school literacy and numeracy tests compared to their peers. Significant predictors included low birthweight, parent not completing school and having > 4 re-hospitalisations in their first six years. The developmental and educational trajectory of children who have had a cardiac procedure in their first year remains altered into primary school years. While perioperative factors did not impact outcomes, ongoing health and sociodemographic factors were important in identifying those children at greatest risk.

Neurodevelopmental outcome of children with congenital heart disease

Congenital heart disease (CHD) constitutes the most common congenital malformation, with moderate or severe CHD occurring in around 6 in 1000 live births. Due to advances in medical care, survival rates have increased significantly. Thus, the majority of children with CHD survive until adolescence and adulthood. Children with CHD requiring cardiopulmonary bypass surgery are at risk for neurodevelopmental impairments in various domains, including mild impairments in cognitive and neuromotor functions, difficulties with social interaction, inattention, emotional symptoms, and impaired executive function. The prevalence for these impairments ranges from 20% to 60% depending on age and domain ("high prevalence-low severity"). Domains are often affected simultaneously, leading to school problems with the need for learning support and special interventions. The etiology of neurodevelopmental impairments is complex, consisting of a combination of delayed intrauterine brain development and newly occurring perioperative brain injuries. Mechanisms include altered intrauterine hemodynamic flow as well as neonatal hypoxia and reduced cerebral blood flow. The surgical procedure and postoperative phase add to this cascade of factors interfering with normal brain development. Early identification of children at high risk through structured follow-up programs is mandated to provide individually tailored early interventions and counseling to improve developmental health.

Microvascular fluid exchange during CPB with deep hypothermia circulatory arrest or low flow

OBJECTIVE

Use of deep hypothermic low-flow (DHLF) cardiopulmonary bypass (CPB) has been associated with higher fluid loading than the use of deep hypothermia circulatory arrest (DHCA). We evaluated whether these perfusion strategies influenced fluid extravasation rates and edema generation differently per-operatively.

MATERIALS AND METHODS

Twelve anesthetized pigs, randomly allocated to DHLF (n = 6) or DHCA (n = 6), underwent 2.5 hours CPB with cooling to 20°C for 30 minutes (min), followed by 30 min arrested circulation (DHCA) or 30 min low-flow circulation (DHLF) before 90 min rewarming to normothermia. Perfusion of tissues, fluid requirements, plasma volumes, colloid osmotic pressures and total tissue water contents were recorded and fluid extravasation rates calculated. During the experiments, cerebral microdialysis was performed in both groups.

RESULTS

Microvascular fluid homeostasis was similar in both groups, with no between-group differences, reflected by similar fluid extravasation rates, plasma colloid osmotic pressures and total tissue water contents. Although extravasation rates increased dramatically from 0.10 (0.11) ml/kg/min (mean with standard deviation in parentheses) and 0.16 (0.02) ml/kg/min to 1.28 (0.58) ml/kg/min and 1.06 (0.41) ml/kg/min (DHCA and DHLF, respectively) after the initiation of CPB, fluid filtrations during both cardiac arrest and low flow were modest and close to baseline values. Cerebral microdialysis indicated anaerobic metabolism and ischemic brain injury in the DHCA group.

CONCLUSION

No differences in microvascular fluid exchange could be demonstrated as a direct effect of DHCA compared with DHLF. Thirty minutes of DHCA was associated with anaerobic cerebral metabolism and possible brain injury.

Clinical Factors Associated with Cerebral Metabolism in Term Neonates with Congenital Heart Disease

OBJECTIVE

To determine associations between patient and clinical factors with postnatal brain metabolism in term neonates with congenital heart disease (CHD) via the use of quantitative magnetic resonance spectroscopy.

STUDY DESIGN

Neonates with CHD were enrolled prospectively to undergo pre- and postoperative 3T brain magnetic resonance imaging. Short-echo single-voxel magnetic resonance spectroscopy of parietal white matter was used to quantify metabolites related to brain maturation (n-acetyl aspartate, choline, myo- inositol), neurotransmitters (glutamate and gamma-aminobutyric acid), energy metabolism (glutamine, citrate, glucose, and phosphocreatine), and injury/apoptosis (lactate and lipids). Multivariable regression was performed to search for associations between (1) patient-specific/prenatal/preoperative factors with concurrent brain metabolism and (2) intraoperative and postoperative factors with postoperative brain metabolism.

RESULTS

A total of 83 magnetic resonance images were obtained on 55 subjects. No patient-specific, prenatal, or preoperative factors associated with concurrent metabolic brain dysmaturation or elevated lactate could be identified. Chromosome 22q11 microdeletion and age at surgery were predictive of altered concurrent white matter phosphocreatine (P < .0055). The only significant intraoperative association found was increased deep hypothermic circulatory arrest time with reduced postoperative white matter glutamate and gamma-aminobutyric acid (P < .0072). Multiple postoperative factors, including increased number of extracorporeal membrane oxygenation days (P < .0067), intensive care unit, length of stay (P < .0047), seizures in the intensive care unit (P < .0009), and home antiepileptic use (P < .0002), were associated with reduced postoperative white matter n-acetyl aspartate.

CONCLUSION

Multiple postoperative factors were found to be associated with altered brain metabolism in term infants with CHD, but not patient-specific, preoperative, or intraoperative factors.

Neurological Complications of Cardiac Disease

This article focuses on the complex interactions between the cardiovascular and neurologic systems. Initially, we focus on neurological complications in children with congenital heart disease both secondary to the underlying cardiac disease and complications of interventions. We later discuss diagnosis and management of common syncope syndromes with emphasis on vasovagal syncope. We also review the diagnosis, classification, and management of children and adolescents with postural orthostatic tachycardia syndrome. Lastly, we discuss long QT syndrome and sudden unexpected death in epilepsy (SUDEP), reviewing advances in genetics and current knowledge of pathophysiology of these conditions. This article attempts to provide an overview of these disorders with focus on pathophysiology, advances in molecular genetics, and current medical interventions.

Postoperative Amplitude-Integrated Electroencephalography Predicts Four-Year Neurodevelopmental Outcome in Children with Complex Congenital Heart Disease

OBJECTIVES

To evaluate the predictive value of pre- and postoperative amplitude-integrated electroencephalography (aEEG) on neurodevelopmental outcomes in children operated for congenital heart disease (CHD).

STUDY DESIGN

Prospectively enrolled cohort of 60 infants with CHD who underwent cardiac surgery with cardiopulmonary bypass in the first 3 months of life. Infants with a genetic comorbidity were excluded. aEEG was assessed for 12 hours pre- and 48 hours postoperatively. Background pattern was classified by the use of standard categories, and the presence of seizures and sleep-wake cycles (SWCs) was noted. Outcome at 1 and 4 years of age was assessed with standardized developmental tests.

RESULTS

Preoperatively, infants either showed continuous normal voltage (n = 56) or discontinuous normal voltage (n = 4). Postoperatively, abnormal background pattern (flat trace, burst suppression, or continuous low voltage) was detected in 7 (12%), discontinuous normal voltage in 37 (61%), and continuous normal voltage in 16 (27%) infants. Nineteen infants (32%) did not return to normal SWCs within the recording period. Seizures were detected in 4 infants preoperatively and in another 4 postoperatively. After we controlled for surgical and postoperative risk factors, abnormal postoperative background pattern and lack of return to SWCs independently predicted poorer intelligence quotient at 4 years (P = .03 and P = .04 respectively) but was not related to motor outcome.

CONCLUSION

aEEG is a useful bedside tool that helps to predict outcome in infants undergoing open-heart surgery for CHD. Abnormal postoperative background pattern and lack of return to SWCs are markers for subsequent impaired cognitive development.

Brain Monitoring and Protection During Pediatric Cardiac Surgery

With advances in medical care, survival after cardiac surgery for congenital heart disease has dramatically improved, and attention is increasingly focused on longterm functional morbidities, especially neurodevelopmental outcomes, with their profound consequences to patients and society. There are multiple reasons for concern about brain injury. Some cardiac defects are associated with brain anomalies and altered cerebral blood flow regulation. Brain imaging studies have demonstrated that injury to gray and white matter is quite frequent before heart surgery in neonates. Cardiopulmonary bypass and deep hypothermic circulatory arrest are associated with shortand longer-term adverse neurologic outcome. Additional brain injury can occur during the patient's recovery from surgery. Strategies to optimize neurologic outcome continue to evolve. With new technological developments, perioperative neurologic monitoring of small children has become easier, and data suggest these modalities usefully identify adverse neurologic events and might predict outcome. Monitoring methods to be discussed include processed electroencephalography, near infrared spectroscopy, and transcranial Doppler ultrasound. Alternative perfusion techniques to deep hypothermic circulatory arrest have been developed, such as regional antegrade cerebral perfusion during cardiopulmonary bypass. Other neuroprotective strategies employed during open-heart surgery include temperature regulation, acid-base management, degree of hemodilution, blood glucose control and anti-inflammatory therapies. Evidence of the impact of these measures on neurologic outcome is examined, and deficiencies in our current understanding of neurologic function in children with congenital heart disease are identified.

The Postoperative Care of Adult Patients Exposed to Deep Hypothermic Circulatory Arrest

Deep hypothermic circulatory arrest with cardiopulmonary bypass is indicated for complex surgical operations in adult patients involving the aortic arch, thoracoabdominal aorta, cerebral vasculature, and tumors extending into the vena cava and heart. Understanding the principles of ischemic-reperfusion injury and the effects of hypothermia in attenuating this process is fundamental to the delivery of effective postoperative care. Neurologic injury is the most troublesome adverse effect after the use of deep hypothermic circulatory arrest and cardiopulmonary bypass, presenting as either a transient neurologic deficit (5.9% to 28.1%) or an irreversible neurologic injury (1.8% to 13.6%). In patients with neurological injury, early postoperative mortality is markedly increased (18.2%), and for those patients that survive, long-term cognitive disability is still evident 6 months later. Early postoperative support of organ function, along with timely diagnosis and treatment of organ injury, is essential in minimizing perioperative morbidity, particularly neurologic morbidity. Meticulous management of fluids, maintaining stable cardiovascular hemodynamics with particular attention to systolic blood pressure, optimizing oxygen delivery, limiting ventilatorassociated lung injury, intensive insulin therapy for control of blood glucose levels, and avoidance of hyperthermia are essential in limiting organ injury and reducing perioperative morbidity and mortality.

Goal-directed-perfusion in neonatal aortic arch surgery

Reduction of mortality and morbidity in congenital cardiac surgery has always been and remains a major target for the complete team involved. As operative techniques are more and more standardized and refined, surgical risk and associated complication rates have constantly been reduced to an acceptable level but are both still present. Aortic arch surgery in neonates seems to be of particular interest, because perfusion techniques differ widely among institutions and an ideal form of a so called "total body perfusion (TBP)" is somewhat difficult to achieve. Thus concepts of deep hypothermic circulatory arrest (DHCA), regional cerebral perfusion (RCP/with cardioplegic cardiac arrest or on the perfused beating heart) and TBP exist in parallel and all carry an individual risk for organ damage related to perfusion management, chosen core temperature and time on bypass. Patient safety relies more and more on adequate end organ perfusion on cardiopulmonary bypass, especially sensitive organs like the brain, heart, kidney, liver and the gut, whereby on adequate tissue protection, temperature management and oxygen delivery should be visualized and monitored.

Long-Term Neurodevelopmental Outcome of Children Treated with Tri-Iodothyronine after Cardiac Surgery: Follow-Up of a Double-Blind, Randomized, Placebo-Controlled Study

BACKGROUND

Transient thyroid dysfunction occurs in children after cardiopulmonary bypass (CPB). We demonstrated significant benefits of acute postoperative tri-iodothyronine (T3) treatment for recovery and myocardial function. Now we report the long-term neurodevelopment of these children.

METHODS

Twenty-eight children (70% of the original study population) could be recruited for a follow-up examination (median age 10.7 years, range 10-19.6 years) retaining the double-blind, randomized, placebo-controlled protocol. Cognitive function and motor development were tested, as were growth and thyroid and cardiac functions.

RESULTS

The median full-scale intelligence quotient of all children was within the reference range and similar in the placebo and T3 groups. Tests for motor and cognitive functions, growth, and thyroid and cardiac functions revealed concurrent results.

CONCLUSIONS

Overall intellectual development is preserved in adolescents treated with CPB in infancy irrespectively of low postoperative thyroid hormone concentrations. While acute postoperative T3 treatment in children after CPB improves recovery, no significant long-term effects on neurodevelopment could be detected. We therefore speculate that transient postoperative thyroid dysfunction by means of nonthyroidal illness syndrome is predominantly mediated by extranuclear, nongenomic mechanisms and thus acutely affects the cardiovascular system but not the development of the central nervous system mediated by genomic mechanisms.

Neurologic Injury Associated with Rewarming from Hypothermia: Is Mild Hypothermia on Bypass Better than Deep Hypothermic Circulatory Arrest?

Many known risk factors for adverse cardiovascular and neurological outcomes in children with congenital heart defects (CHD) are not modifiable; however, the temperature and blood flow during cardiopulmonary bypass (CPB), are two risk factors, which may be altered in an attempt to improve long-term neurological outcomes. Deep hypothermic circulatory arrest, traditionally used for aortic arch repair, has been associated with short-term and long-term neurologic sequelae. Therefore, there is a rising interest in using moderate hypothermia with selective antegrade cerebral blood flow on CPB during aortic arch repair. Rewarming from moderate-to-deep hypothermia has been shown to be associated with neuronal injury, neuroinflammation, and loss of cerebrovascular autoregulation. A significantly lesser degree of rewarming is required following mild (33-35°C) hypothermia as compared with moderate (28-32°C), deep (21-27°C), and profound (less than 20°C) hypothermia. Therefore, we believe that mild hypothermia is associated with a lower risk of rewarming-induced neurologic injury. We hypothesize that mild hypothermia with selective antegrade cerebral perfusion during CPB for neonatal aortic arch repair would be associated with improved neurologic outcome.

Flupirtine effectively prevents development of acute neonatal seizures in an animal model of global hypoxia

Current first-line drugs for the treatment of neonatal seizures have limited efficacy and are associated with side effects. Uncontrolled seizures may exacerbate brain injury and contribute to later-life neurological disability. Therefore, it is critical to develop a treatment for neonatal seizures that is effective and safe. In early-life, when the γ-aminobutyric acid (GABA) inhibitory system is not fully developed, potassium channels play an important role in controlling excitability. An earlier study demonstrated that flupirtine, a KCNQ potassium channel opener, is more efficacious than diazepam and phenobarbital for the treatment of chemoconvulsant-induced neonatal seizures. In newborns, seizures are most commonly associated with hypoxic-ischemic encephalopathy (HIE). Thus, in the present study, we examined the efficacy of flupirtine to treat neonatal seizures in an animal model of global hypoxia. Our results showed that flupirtine dose dependently blocks the occurrence of behavioral seizures in pups during hypoxia. Additionally, flupirtine inhibits the development of hypoxia-induced clinical seizures and associated epileptiform discharges, as well as purely electrographic (subclinical) seizures. These results suggest that flupirtine is an effective anti-seizure drug, and that further studies should be conducted to determine the time window within which it's administration can effectively treat neonatal seizures.