Risk factors for preoperative periventricular leukomalacia in term neonates with hypoplastic left heart syndrome are patient related

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.

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.

Cerebral Blood Flow, Brain Injury, and Aortic-Pulmonary Collateral Flow After the Fontan Operation

Patients with a single ventricle develop aortopulmonary collaterals (APCs) whose flow has been shown to be inversely proportional to cerebral blood flow (CBF) in a previous cross-sectional study. Longitudinal CBF and APC flow in patients with Fontan physiology adjusting for brain injury (BI) has never been reported. Decreased CBF and BI may adversely impact neurodevelopment. A prospective longitudinal cohort of 27 patients with Fontan physiology (aged 10 ± 1.9 years, 74% male) underwent cardiac and brain magnetic resonance imaging 3 to 9 months and 6.0 ± 1.86 years after Fontan operation to measure the CBF and APC flow and to reassess the BI (focal BI, generalized insult, and hemorrhage). CBF was measured using jugular venous flow and APC flow was measured by the difference between aortic flow and caval return. Multivariate modeling was used to assess the relation between the change in APC flow and BI. A strong inverse relation was found between CBF/aortic flow change and APC flow/aortic flow and APC flow/body surface area change (R2 = 0.70 and 0.72 respectively, p <0.02). Overall, the CBF decreased by 9 ± 11% and the APC flow decreased by 0.73 ± 0.67 l/min/m2. The evolution of CBF and APC flow were significantly and inversely related when adjusting for time since Fontan operation, gender, and BI on the multivariate modeling. Every unit increase in APC flow change was associated with an 8% decrease in CBF change. In conclusion, CBF and APC flow change are inversely related across serial imaging, adjusting for time from Fontan operation, gender, and BI. CBF and APC aortic flow decrease over a 6-year period. This may adversely impact neurodevelopment. Because APCs can be embolized, this may be a modifiable risk factor. Clinical trials numbers: NCT02135081 and NCT02919956.

Preterm congenital heart disease and neurodevelopment: the importance of looking beyond the initial hospitalization

Congenital heart disease (CHD) and prematurity are leading causes of infant mortality in the United States. Infants with CHD born prematurely are often described as facing "double jeopardy" with vulnerability from their underlying heart disease and from organ immaturity. They endure additional complications of developing in the extrauterine environment while healing from interventions for heart disease. While morbidity and mortality for neonates with CHD have declined over the past decade, preterm neonates with CHD remain at higher risk for adverse outcomes. Less is known about their neurodevelopmental and functional outcomes. In this perspective paper, we review the prevalence of preterm birth among infants with CHD, highlight the medical complexity of these infants, and emphasize the importance of exploring outcomes beyond survival. We focus on current knowledge regarding overlaps in the mechanisms of neurodevelopmental impairment associated with CHD and prematurity and discuss future directions for improving neurodevelopmental outcomes.

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.

Ketamine for Management of Neonatal and Pediatric Refractory Status Epilepticus

BACKGROUND AND OBJECTIVES

Few data are available regarding the use of anesthetic infusions for refractory status epilepticus (RSE) in children and neonates, and ketamine use is increasing despite limited data. We aimed to describe the impact of ketamine for RSE in children and neonates.

METHODS

Retrospective single-center cohort study of consecutive patients admitted to the intensive care units of a quaternary care children's hospital treated with ketamine infusion for RSE.

RESULTS

Sixty-nine patients were treated with a ketamine infusion for RSE. The median age at onset of RSE was 0.7 years (interquartile range 0.15-7.2), and the cohort included 13 (19%) neonates. Three patients (4%) had adverse events requiring intervention during or within 12 hours of ketamine administration, including hypertension in 2 patients and delirium in 1 patient. Ketamine infusion was followed by seizure termination in 32 patients (46%), seizure reduction in 19 patients (28%), and no change in 18 patients (26%).

DISCUSSION

Ketamine administration was associated with few adverse events, and seizures often terminated or improved after ketamine administration. Further data are needed comparing first-line and subsequent anesthetic medications for treatment of pediatric and neonatal RSE.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence on the therapeutic utility of ketamine for treatment of RSE in children and neonates.

Scoring of brain magnetic resonance imaging and neurodevelopmental outcomes in infants with congenital heart disease

BACKGROUND

Advances in surgical techniques to tackle critical congenital heart diseases (CHD) have enhanced the survival rates and life expectancy of children born with heart disease. Studies to better acknowledge their neurodevelopmental trajectory have paramount implications.

OBJECTIVE

The aim of this study is to examine the nature of brain MRI findings in infants born with critical congenital heart diseases needing intervention in the first 6 months of life, with the help of an MRI scoring system and correlation with long term neurodevelopmental outcomes.

METHODS

Brain MRI scans of eligible infants were extracted from database, reexamined to categorize, and score them into three main functional areas: cognitive/grey matter, motor/white matter, and visual. The scoring system also included stage of myelination and presence of punctate hemorrhages. The correlation of individual and total MRI scores with neurodevelopmental assessment using Bayley Scales for Infant and Toddler Development- version 3 (BSID III) were examined via logistic regression models while controlling for confounding variables.

RESULT

Median (IQR) MRI score was 6 (4-7) with grey matter score of 2 (1-4). Initial BSID III scores were 80 ± 15, 80 ± 18, and 81 ± 19 for cognitive, motor and language components, respectively. The MRI cognitive score had direct correlation with respiratory index prior to surgery (cc = 0.47, p = 0.03) and cross-clamping time (cc = 0.65, p = 0.001). It displayed a significant inverse correlation with language scores for BSID III at 9 months (R = -0.42, p = 0.04) which lost significance in subsequent visits.

CONCLUSION

This pilot study proved the feasibility of correlating structural brain abnormalities in MRI with later brain developmental deficits in infants with CHD. We envision establishing a standardized MRI scoring system to be performed on a large multi-center cohort that would help better predict and measure brain injury in infants with CHDs.

Oral feeding dysfunction in post-operative infants with CHDs: a scoping review

Post-operative oral feeding difficulties in neonates and infants with CHD is common. While pre-operative oral feeding may be normal, oral feeding challenges manifest in the post-operative period without a clearly defined aetiology. The objective of this scoping review was to examine post-operative oral feeding in full-term neonates and infants with a CHD. Electronic databases query (1 January 1975-31 May 2021), hand-search of the reference lists of included studies, contact with experts, and review of relevant conferences were performed to identify quantitative studies evaluating post-operative oral feeding in full-term neonates and infants with a CHD. Associations with additional quantitative variables in these studies were also examined. Twenty-five studies met inclusion criteria. Eighty per cent were cohort studies that utilised retrospective chart review from a single institution. The primary variable of interest in all studies was oral feeding status upon discharge from neonatal hospitalisation. The most common risk factors evaluated with poor feeding at time of discharge were birth weight (36% of included studies), gestational age (44%), duration of post-operative intubation (48%), cardiac diagnosis (40%), and presence of genetic syndrome or chromosomal anomaly (36%). The most common health-related outcomes evaluated were length of hospital stay (40%) and length of ICU stay (16%). Only the health-related outcomes of length of hospital stay and length of ICU stay were consistently significantly associated with poor post-operative oral feeding across studies in this review. A clear aetiology of poor post-operative oral feeding remains unknown.

Functional brain maturation and sleep organisation in neonates with congenital heart disease

OBJECTIVE

Neonates with Congenital Heart Disease (CHD) have structural delays in brain development. To evaluate whether functional brain maturation and sleep-wake physiology is also disturbed, the Functional Brain Age (FBA) and sleep organisation on EEG during the neonatal period is investigated.

METHODS

We compared 15 neonates with CHD who underwent multichannel EEG with healthy term newborns of the same postmenstrual age, including subgroup analysis for d-Transposition of the Great Arteries (d-TGA) (n = 8). To estimate FBA, a prediction tool using quantitative EEG features as input, was applied. Second, the EEG was automatically classified into the 4 neonatal sleep stages. Neonates with CHD underwent neurodevelopmental testing using the Bayley Scale of Infant Development-III at 24 months.

RESULTS

Preoperatively, the FBA was delayed in CHD infants and more so in d-TGA infants. The FBA was positively correlated with motor scores. Sleep organisation was significantly altered in neonates with CHD. The duration of the sleep cycle and the proportion of Active Sleep Stage 1 was decreased, again more marked in the d-TGA infants. Neonates with d-TGA spent less time in High Voltage Slow Wave Sleep and more in Tracé Alternant compared to healthy terms. Both FBA and sleep organisation normalised postoperatively. The duration of High Voltage Slow Wave Sleep remained positively correlated with motor scores in d-TGA infants.

INTERPRETATION

Altered early brain function and sleep is present in neonates with CHD. These results are intruiging, as inefficient neonatal sleep has been linked with adverse long-term outcome. Identifying how these rapid alterations in brain function are mitigated through improvements in cerebral oxygenation, surgery, drugs and nutrition may have relevance for clinical practice and outcome.

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.

Fetal brain growth and risk of postnatal white matter injury in critical congenital heart disease

OBJECTIVE

To test the hypothesis that delayed brain development in fetuses with d-transposition of the great arteries or hypoplastic left heart syndrome heightens their postnatal susceptibility to acquired white matter injury.

METHODS

This is a cohort study across 3 sites. Subjects underwent fetal (third trimester) and neonatal preoperative magnetic resonance imaging of the brain to measure total brain volume as a measure of brain maturity and the presence of acquired white matter injury after birth. White matter injury was categorized as no-mild or moderate-severe based on validated grading criteria. Comparisons were made between the injury groups.

RESULTS

A total of 63 subjects were enrolled (d-transposition of the great arteries: 37; hypoplastic left heart syndrome: 26). White matter injury was present in 32.4% (n = 12) of d-transposition of the great arteries and 34.6% (n = 8) of those with hypoplastic left heart syndrome. Overall total brain volume (taking into account fetal and neonatal scan) was significantly lower in those with postnatal moderate-severe white matter injury compared with no-mild white matter injury after adjusting for age at scan and site in d-transposition of the great arteries (coefficient: 14.8 mL, 95% confidence interval, -28.8 to -0.73, P = .04). The rate of change in total brain volume from fetal to postnatal life did not differ by injury group. In hypoplastic left heart syndrome, no association was noted between overall total brain volume and change in total brain volume with postnatal white matter injury.

CONCLUSIONS

Lower total brain volume beginning in late gestation is associated with increased risk of postnatal moderate-severe white matter injury in d-transposition of the great arteries but not hypoplastic left heart syndrome. Rate of brain growth was not a risk factor for white matter injury. The underlying fetal and perinatal physiology has different implications for postnatal risk of white matter injury.

The Feasibility of Kangaroo Care and the Effect on Maternal Attachment for Neonates in a Pediatric Cardiac Intensive Care Unit

BACKGROUND

As survival rates in neonates with congenital heart disease have improved, research has shown they are at an increased risk for brain injury and neurodevelopmental delay. One intervention shown to have a positive impact on the development in premature and full-term newborns, as well as a positive impact on mother-infant relationship, is kangaroo care (KC). There is limited evidence to support the use of KC in infants with congenital heart disease, some of who may also be premature.

PURPOSE

The purpose of this study was to examine the safety and feasibility of introducing KC for neonates with congenital heart disease in the pediatric cardiac intensive care unit.

METHODS

A descriptive observational feasibility study was employed to evaluate the safety and efficacy of KC for this population.

RESULTS

There were 25 neonates included with 60 sessions of KC. There were no adverse events including line and tube dislodgments and physiological instability related to the use of KC.

IMPLICATIONS FOR PRACTICE

This study found KC to be safe and feasible for neonates with KC.

IMPLICATIONS FOR RESEARCH

This is the first study examining the feasibility and safety of KC in this vulnerable population of neonates. Further research should be conducted using a quasi-experimental design to investigate neurodevelopmental outcomes with a larger sample of patients.

Developmental outcomes after early surgery for complex congenital heart disease: a systematic review and meta-analysis

AIM

(1) To systematically review the literature on developmental outcomes from infancy to adolescence of children with complex congenital heart disease (CHD) who underwent early surgery; (2) to run a meta-regression analysis on the Bayley Scales of Infant Development, Second Edition Mental Developmental Index and Psychomotor Developmental Index (PDI) of infants up to 24 months and IQs of preschool-aged children to adolescents; (3) to assess associations between perioperative risk factors and outcomes.

METHOD

We searched pertinent literature (January 1990 to January 2019) in PubMed, Embase, CINAHL, and PsycINFO. Selection criteria included infants with complex CHD who had primary surgery within the first 9 weeks of life. Methodological quality, including risk of bias and internal validity, were assessed.

RESULTS

In total, 185 papers met the inclusion criteria; the 100 with high to moderate methodological quality were analysed in detail. Substantial heterogeneity in the group with CHD and in methodology existed. The outcome of infants with single-ventricle CHD was inferior to those with two-ventricle CHD (respectively: average scores for PDI 77 and 88; intelligence scores 92 and 98). Perioperative risk factors were inconsistently associated with developmental outcomes.

INTERPRETATION

The literature on children undergoing surgery in early infancy suggests that infants with a single ventricle are at highest risk of adverse developmental outcomes.

Early Evaluation and the Effect of Socioeconomic Factors on Neurodevelopment in Infants with Tetralogy of Fallot

Neurodevelopmental sequelae are prevalent among patients with congenital heart defects (CHD). In a study of infants and children with repaired tetralogy of Fallot (TOF), we sought to identify those at risk for abnormal neurodevelopment and to test associations between socioeconomic and medical factors with neurodevelopment deficits. Single-center retrospective observational study of patients with repaired TOF that were evaluated at the institution's Cardiac Kids Developmental Follow-up Program (CKDP) between 2012 and 2018. Main outcomes included neurodevelopmental test scores from the Bayley Infant Neurodevelopmental Screener (BINS), Peabody Developmental Motor Scale (PDMS), and Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Mixed effects linear regression and marginal logistic regression models tested relationships between patient characteristics and outcomes. Sub-analyses were conducted to test correlations between initial and later neurodevelopment tests. In total, 49 patients were included, predominantly male (n = 33) and white (n = 28), first evaluated at a median age of 4.5 months. Forty-three percent of patients (n = 16) had deficits in the BINS, the earliest screening test. Several socioeconomic parameters and measures of disease complexity were associated with neurodevelopment, independently of genetic syndrome. Early BINS and PDMS performed in infancy were associated with Bayley-III scores performed after 1 year of age. Early screening identifies TOF patients at risk for abnormal neurodevelopment. Socioeconomic factors and disease complexity are associated with abnormal neurodevelopment and should be taken into account in the risk stratification and follow-up of these patients. Early evaluation with BINS and PDMS is suggested for detection of early deficits.

Antenatal and Perioperative Mechanisms of Global Neurological Injury in Congenital Heart Disease

Congenital heart defects (CHD) is one of the most common types of birth defects. Thanks to advances in surgical techniques and intensive care, the majority of children with severe forms of CHD survive into adulthood. However, this increase in survival comes with a cost. CHD survivors have neurological functioning at the bottom of the normal range. A large spectrum of central nervous system dysmaturation leads to the deficits seen in critical CHD. The heart develops early during gestation, and CHD has a profound effect on fetal brain development for the remainder of gestation. Term infants with critical CHD are born with an immature brain, which is highly susceptible to hypoxic-ischemic injuries. Perioperative blood flow disturbances due to the CHD and the use of cardiopulmonary bypass or circulatory arrest during surgery cause additional neurological injuries. Innate patient factors, such as genetic syndromes and preterm birth, and postoperative complications play a larger role in neurological injury than perioperative factors. Strategies to reduce the disability burden in critical CHD survivors are urgently needed.

Fetal Cerebral Oxygenation Is Impaired in Congenital Heart Disease and Shows Variable Response to Maternal Hyperoxia

Background

Impairments in fetal oxygen delivery have been implicated in brain dysmaturation seen in congenital heart disease (CHD), suggesting a role for in utero transplacental oxygen therapy. We applied a novel imaging tool to quantify fetal cerebral oxygenation by measuring T2* decay. We compared T2* in fetuses with CHD with controls with a focus on cardiovascular physiologies (transposition or left‐sided obstruction) and described the effect of brief administration of maternal hyperoxia on T2* decay.

Methods and Results

This is a prospective study performed on pregnant mothers with a prenatal diagnosis of CHD compared with controls in the third trimester. Participants underwent a fetal brain magnetic resonance imaging scan including a T2* sequence before and after maternal hyperoxia. Comparisons were made between control and CHD fetuses including subgroup analyses by cardiac physiology. Forty‐four mothers (CHD=24, control=20) participated. Fetuses with CHD had lower total brain volume (238.2 mm³, 95% CI, 224.6–251.9) compared with controls (262.4 mm³, 95% CI, 245.0–279.8, P=0.04). T2* decay time was faster in CHD compared with controls (beta=−14.4, 95% CI, −23.3 to −5.6, P=0.002). The magnitude of change in T2* with maternal hyperoxia was higher in fetuses with transposition compared with controls (increase of 8.4 ms, 95% CI, 0.5–14.3, P=0.01), though between‐subject variability was noted.

Conclusions

Cerebral tissue oxygenation is lower in fetuses with complex CHD. There was variability in the response to maternal hyperoxia by CHD subgroup that can be tested in future larger studies. Cardiovascular physiology is critical when designing neuroprotective clinical trials in the fetus with CHD.

Postoperative Improvement of Brain Maturation in Infants With Congenital Heart Disease

Children with severe congenital heart disease are at risk for neurodevelopmental impairments. We examined brain maturation in infants undergoing neonatal cardiopulmonary bypass surgery or hybrid procedure for hypoplastic left heart syndrome compared to controls. This is a prospective cohort study on term-born infants with congenital heart disease with cerebral MRI pre- and postoperatively. Healthy infants served as controls. Brain maturation was measured using a semiquantitative scoring system. The progress of brain maturation from the preoperative to postoperative MRI within patients was compared. Neurodevelopment was assessed at 1 year with the Bayley Scales of Infant and Toddler Development III. A total of 92 patients with congenital heart disease and 46 controls were studied. Median total maturation score in patients was 12 (interquartile range 10.6-13.0) preoperatively and 14 (12.0-15.0) postoperatively, in controls it was 14 (13.0-15.0). Median time interval between scans was 19 days (interquartile range 14-26). After correction for postmenstrual age at MRI, the pre- and postoperative maturation score was lower in patients compared to controls (preoperative P = 0.01, postoperative P = 0.03) and increased between pre- and postoperative assessment (P ≤ 0.001). Brain maturation scores did not correlate with neurodevelopmental outcome at 1 year, when corrected for socioeconomic status and postmenstrual age at MRI. This study confirms delayed brain maturation in children with congenital heart disease, and despite neonatal cardiac bypass surgery followed by postoperative intensive care medicine brain maturation is ongoing. We encourage further investigation in outcome prediction in this population, potentially by combining more advanced MRI measures with clinical methods.

Neuroimaging findings in newborns with congenital heart disease prior to surgery: an observational study

OBJECTIVES

Neurodevelopmental impairment has become the most important comorbidity in infants with congenital heart disease (CHD). We aimed to (1) investigate the burden of brain lesions in infants with CHD prior to surgery and (2) explore clinical factors associated with injury.

STUDY DESIGN

Prospective observational study.

SETTING

Single centre UK tertiary neonatal intensive care unit.

PATIENTS

70 newborn infants with critical or serious CHD underwent brain MRI prior to surgery.

MAIN OUTCOME MEASURES

Prevalence of cerebral injury including arterial ischaemic strokes (AIS), white matter injury (WMI) and intracranial haemorrhage.

RESULTS

Brain lesions were observed in 39% of subjects (95% CI 28% to 50%). WMI was identified in 33% (95% CI 23% to 45%), subdural haemorrhage without mass effect in 33% (95% CI 23% to 45%), cerebellar haemorrhage in 9% (95% CI 4% to 18%) and AIS in 4% (95% CI 1.5% to 12%). WMI was distributed widely throughout the brain, particularly involving the frontal white matter, optic radiations and corona radiata. WMI exhibited restricted diffusion in 48% of cases. AIS was only observed in infants with transposition of the great arteries (TGA) who had previously undergone balloon atrial septostomy (BAS). AIS was identified in 23% (95% CI 8% to 50%) of infants with TGA who underwent BAS, compared with 0% (95% CI 0% to 20%) who did not.

CONCLUSIONS

Cerebral injury in newborns with CHD prior to surgery is common.

Perioperative Assessment of Cerebral Oxygen Metabolism in Infants With Functionally Univentricular Hearts Undergoing the Bidirectional Cavopulmonary Connection

OBJECTIVES

The transition from single-ventricle lesions with surgically placed systemic-to-pulmonary artery shunt to the circulation following a bidirectional cavopulmonary connection results in higher pressure in the superior vena cava when compared with the preceding circulation. The aim of this study was to evaluate the impact of this transition on the perioperative cerebral oxygen metabolism.

DESIGN

Prospective observational cohort study.

SETTING

Pediatric critical care unit of a tertiary referral center.

PATIENTS

Sixteen infants after bidirectional cavopulmonary connection.

INTERVENTION

Cardiac surgery (bidirectional cavopulmonary connection).

MEASUREMENTS AND MAIN RESULTS

We measured regional cerebral oxygen saturation, amount of hemoglobin, blood flow velocity, and microperfusion immediately before, 12-24 hours, and 36-48 hours following bidirectional cavopulmonary connection. Based on these measurements, we calculated cerebral fractional tissue oxygen extraction and approximated cerebral metabolic rate of oxygen. Mean pressure in the superior vena cava increased significantly (8 vs 17 mm Hg; p < 0.001) following bidirectional cavopulmonary connection. Mean cerebral oxygen saturation increased from 49.0% (27.4-61.0) to 56.9% (39.5-64.0) (p = 0.008), whereas mean cerebral blood flow velocity decreased from 80.0 arbitrary units (61.9-93.0) to 67.3 arbitrary units (59.0-83.3) (p < 0.001). No change was found in the cerebral amount of hemoglobin and in the cerebral microperfusion. Mean cerebral fractional tissue oxygen extraction (0.48 [0.17-0.63] vs 0.30 [0.19-0.56]; p = 0.006) and approximated cerebral metabolic rate of oxygen (5.82 arbitrary units [2.70-8.78] vs 2.27 arbitrary units [1.19-7.35]; p < 0.001) decreased significantly.

CONCLUSIONS

Establishment of bidirectional cavopulmonary connection is associated with postoperative improvement in cerebral oxygen metabolism. Cerebral amount of hemoglobin did not increase, although creation of the bidirectional cavopulmonary connection results in significant elevation in superior vena cava pressure. Improvement in cerebral oxygen metabolism was due to lower cerebral blood flow velocity and stable microperfusion, which may indicate intact cerebral autoregulation.

Circulatory Changes and Cerebral Blood Flow and Oxygenation During Transition in Newborns With Congenital Heart Disease

This review aims to describe how the complex events of cardiovascular transition may affect the brain of infants with congenital heart disease (CHD). In particular, we describe the vulnerabilities of the neonatal brain in the transitional period during and immediately after delivery and propose management strategies that can potentially influence neurodevelopmental outcomes in this patient population. Delayed brain development has been identified in the third trimester fetus with certain forms of CHD. Neonates with critical CHD are at risk for brain injury even before their neonatal operation. The transitional period from fetal to neonatal life is marked with hemodynamic changes that can affect cerebral blood flow and oxygenation and may exacerbate injury and influence outcome. We propose specific perinatal management strategies tailored to maternal-fetal pairs aimed at optimizing hemodynamic stability, especially cerebral blood flow and oxygenation, to maximize the neurodevelopmental potential of infants with CHD.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Neuro-developmental outcome in single-ventricle patients: is the Norwood procedure a risk factor?

OBJECTIVES

Complex neonatal surgery is considered a risk factor for neuro-developmental impairment in single-ventricle patients. Neuro-developmental outcome was compared between preschool-aged Fontan patients who underwent a Norwood procedure and single-ventricle patients not requiring neonatal surgery with cardiopulmonary bypass.

METHODS

Verbal, performance and full-scale intelligence quotient (IQ) were evaluated with the Wechsler Preschool and Primary Scale of Intelligence. Cognitive functions were assessed with the German 'Kognitiver Entwicklungstest für das Kindergartenalter' (KET-KID). Risk factors for impaired neuro-development were evaluated.

RESULTS

Neuro-developmental assessment was completed in 95 patients (Norwood: n = 69; non-Norwood: n = 26). Median (interquartile range) IQ and KET-KID scores were in the normal range. Except for verbal KET-KID, scores did not differ between Norwood and non-Norwood patients (verbal IQ: 98 (86-105) vs 93 (85-102), P = 0.312; performance IQ: 91 (86-100) vs 96 (86-100), P = 0.932; full-scale IQ: 93 (86-101) vs 89 (84-98), P = 0.314; KET-KID verbal: 48 (17-72) vs 25 (2-54), P = 0.020; KET-KID non-verbal: 33 (18-62) vs 45 (15-54), P = 0.771; KET-KID global: 42 (14-65) vs 28 (6-63), P = 0.208). Full-scale IQ was below average (<85 points) in 14 (20%) Norwood and 9 (35%) non-Norwood cases (P = 0.181). Global KET-KID was below average (<16th percentile) in 19 (28%) and 10 (38%) patients (P = 0.326). Smaller head circumference z-score and complications before neonatal surgery were independently associated with lower scores.

CONCLUSIONS

Neuro-developmental outcome of preschool-aged Fontan patients was in the normal range. The Norwood procedure was not a risk factor for neuro-developmental impairment. Preoperative condition and patient-related factors were more important determinants than variables related to surgical palliation.

Neonatal Brain Injury and Timing of Neurodevelopmental Assessment in Patients With Congenital Heart Disease

BACKGROUND

Brain injury (BI) is reported in 60% of newborns with critical congenital heart disease as white matter injury (WMI) or stroke. Neurodevelopmental (ND) impairments are reported in these patients. The relationship between neonatal BI and ND outcome has not been established.

OBJECTIVES

This study sought to determine the association between peri-operative BI and ND outcomes in infants with single ventricle physiology (SVP) and d-transposition of the great arteries (d-TGA).

METHODS

Term newborns with d-TGA and SVP had pre-operative and post-operative brain magnetic resonance imaging and ND outcomes assessed at 12 and 30 months with the Bayley Scales of Infant Development-II. BI was categorized by the brain injury severity score and WMI was quantified by volumetric analysis.

RESULTS

A total of 104 infants had follow-up at 12 months and 70 had follow-up at 30 months. At 12 months, only clinical variables were associated with ND outcome. At 30 months, subjects with moderate-to-severe WMI had significantly lower Psychomotor Development Index (PDI) scores (13 points lower) as compared with those with none or minimal WMI for d-TGA and SVP (p = 0.03 and p = 0.05, respectively) after adjusting for various factors. Quantitative WMI volume was likewise associated. Stroke was not associated with outcome. The Bland-Altman limits of agreement for PDI scores at 12 and 30 months were wide (-40.3 to 31.2) across the range of mean PDI values.

CONCLUSIONS

Increasing burden of WMI is associated with worse motor outcomes at 30 months for infants with critical congenital heart disease, whereas no adverse association was seen between small strokes and outcome. These results support the utility of neonatal brain magnetic resonance imaging in this population to aid in predicting later outcomes and the importance of ND follow-up beyond 1 year of age.

Increased Pituitary Volumes in Children after Fontan Operation: Congestion in the Other Portal Circulation

We performed brain magnetic resonance imaging in 40 patients after the Fontan procedure and 40 control subjects. Pituitary volumes in patients after Fontan were significantly larger than those in the control subjects (472 [425-527] vs 257 [182-311]; P < .0001), and were significantly related to central venous pressure.

In Utero Evidence of Impaired Somatic Growth in Hypoplastic Left Heart Syndrome

We hypothesized that fetuses with hypoplastic left heart syndrome (HLHS) have impaired growth compared to expected growth for gestational age. This is a retrospective cohort study including singleton fetuses with isolated HLHS identified from a single, referral center's ultrasound database. To account for variable timing of ultrasounds, z-scores for gestational age were assigned for each biometric parameter. We identified 169 fetuses, of which 96 had more than one ultrasound. The median number of ultrasound evaluations per fetus was 2 (range 1-5). The mean gestational age at time of last ultrasound was 33.7 ± 4.3 weeks with a range of 20.4-39.6 weeks. While fetal growth restriction (11%) and microcephaly (3%) were relatively rare, mean z-scores at the time of last ultrasound for estimated fetal weight (mean difference z-score -0.20, p = 0.04) and head circumference (-0.28, p = 0.02) were lower than at the time of the initial ultrasound. Impaired somatic growth, defined as a decrement in z-score of 0.5 or more over time, was common (32%). There is a deceleration in somatic and head growth in fetuses with hypoplastic left heart syndrome that can be identified by routine ultrasound evaluation.

The association between cardiac physiology, acquired brain injury, and postnatal brain growth in critical congenital heart disease

OBJECTIVE

To assess the trajectory of perioperative brain growth in relationship to cardiac diagnosis and acquired brain injuries.

METHODS

This was a cohort study of term neonates with hypoplastic left heart syndrome (HLHS) and d-transposition of the great arteries (d-TGA). Subjects underwent magnetic resonance imaging of the brain pre- and postoperatively to determine the severity of brain injury and total and regional brain volumes by the use of automated morphometry. Comparisons were made by cardiac lesion and injury status.

RESULTS

A total of 79 subjects were included (49, d-TGA; 30, HLHS). Subjects with HLHS had more postoperative brain injury (55.6% vs 30.4%, P = .03) and more severe brain injury (moderate-to-severe white matter [WM] injury, P = .01). Total and regional perioperative brain growth was not different by brain injury status (either pre- or postoperative). However, subjects with moderate-to-severe WM injury had a slower rate of brain growth in WM and gray matter compared with those with no injury. Subjects with HLHS had a slower rate of growth globally and in WM and deep gray matter as compared with d-TGA (total brain volume: 12 cm³/wk vs 7 cm³; WM: 2.1 cm³/wk vs 0.6 cm³; deep gray matter: 1.5 cm³/wk vs 0.7 cm³; P < .001), after we adjusted for gestational age at scan and the presence of brain injury. This difference remained after excluding subjects with moderate-to-severe WM injury.

CONCLUSIONS

Neonates with HLHS have a slower rate of global and regional brain growth compared with d-TGA, likely related to inherent physiologic differences postoperatively. These findings demonstrate the complex interplay between cardiac lesion, brain injury, and brain growth.

Brain Injury and Neurodevelopmental Outcome in Congenital Heart Disease: A Systematic Review

CONTEXT

Brain injury during prenatal and preoperative postnatal life might play a major role in neurodevelopmental impairment in infants with congenital heart disease (CHD) who require corrective or palliative surgery during infancy. A systematic review of cerebral findings during this period in relation to neurodevelopmental outcome (NDO), however, is lacking.

OBJECTIVE

To assess the association between prenatal and postnatal preoperative cerebral findings and NDO in infants with CHD who require corrective or palliative surgery during infancy.

DATA SOURCES

PubMed, Embase, reference lists.

STUDY SELECTION

We conducted 3 different searches for English literature between 2000 and 2016; 1 for prenatal cerebral findings, 1 for postnatal preoperative cerebral findings, and 1 for the association between brain injury and NDO.

DATA EXTRACTION

Two reviewers independently screened sources and extracted data on cerebral findings and neurodevelopmental outcome. Quality of studies was assessed using the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Abnormal cerebral findings are common during the prenatal and postnatal preoperative periods. Prenatally, a delay of cerebral development was most common; postnatally, white matter injury, periventricular leukomalacia, and stroke were frequently observed. Abnormal Doppler measurements, brain immaturity, cerebral oxygenation, and abnormal EEG or amplitude-integrated EEG were all associated with NDO.

LIMITATIONS

Observational studies, different types of CHD with different pathophysiological effects, and different reference values.

CONCLUSIONS

Prenatal and postnatal preoperative abnormal cerebral findings might play an important role in neurodevelopmental impairment in infants with CHD. Increased awareness of the vulnerability of the young developing brain of an infant with CHD among caregivers is essential.

Neurological Injury and Cerebral Blood Flow in Single Ventricles Throughout Staged Surgical Reconstruction

BACKGROUND

Patients with a single ventricle experience a high rate of brain injury and adverse neurodevelopmental outcome; however, the incidence of brain abnormalities throughout surgical reconstruction and their relationship with cerebral blood flow, oxygen delivery, and carbon dioxide reactivity remain unknown.

METHODS

Patients with a single ventricle were studied with magnetic resonance imaging scans immediately prior to bidirectional Glenn (pre-BDG), before Fontan (BDG), and then 3 to 9 months after Fontan reconstruction.

RESULTS

One hundred sixty-eight consecutive subjects recruited into the project underwent 235 scans: 63 pre-BDG (mean age, 4.8±1.7 months), 118 BDG (2.9±1.4 years), and 54 after Fontan (2.4±1.0 years). Nonacute ischemic white matter changes on T2-weighted imaging, focal tissue loss, and ventriculomegaly were all more commonly detected in BDG and Fontan compared with pre-BDG patients (P<0.05). BDG patients had significantly higher cerebral blood flow than did Fontan patients. The odds of discovering brain injury with adjustment for surgical stage as well as ≥2 coexisting lesions within a patient decreased (63%-75% and 44%, respectively) with increasing amount of cerebral blood flow (P<0.05). In general, there was no association of oxygen delivery (except for ventriculomegaly in the BDG group) or carbon dioxide reactivity with neurological injury.

CONCLUSIONS

Significant brain abnormalities are commonly present in patients with a single ventricle, and detection of these lesions increases as children progress through staged surgical reconstruction, with multiple coexisting lesions more common earlier than later. In addition, this study demonstrated that BDG patients had greater cerebral blood flow than did Fontan patients and that an inverse association exists of various indexes of cerebral blood flow with these brain lesions. However, CO₂ reactivity and oxygen delivery (with 1 exception) were not associated with brain lesion development.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02135081.

School-Age Test Proficiency and Special Education After Congenital Heart Disease Surgery in Infancy

OBJECTIVE

To evaluate test proficiency and the receipt of special education services in school-age children who had undergone surgery for congenital heart disease (CHD) at age <1 year.

STUDY DESIGN

Data from Arkansas-born children who underwent surgery for CHD at Arkansas Children's Hospital at age <1 year between 1996 and 2004 were linked to state birth certificates and the Arkansas Department of Education longitudinal database containing achievement test scores in literacy and mathematics for grades 3-4 and special education codes. The primary negative outcome was not achieving grade-level proficiency on achievement tests. Logistic regression accounting for repeated measures was used to evaluate for associations between achieving proficiency and demographic data, maternal education, and clinical factors.

RESULTS

A total of 362 of 458 (79%) children who underwent surgery for CHD were matched to the Arkansas Department of Education database, 285 of whom had grade 3 and/or 4 achievement tests scores. Fewer students with CHD achieved proficiency in literacy and mathematics (P < .05) compared with grade-matched state students. Higher 5-minute Apgar score, shorter duration of hospitalization, and higher maternal education predicted proficiency in literacy (P < .05). White race, no cardiopulmonary bypass, and shorter hospitalization predicted proficiency in mathematics (P < .05). Sex, gestational age, age at surgery, CHD diagnosis, and type and number of surgeries did not predict test proficiency. Compared with all public school students, more children with CHD received special education services (26.9% vs 11.6%; P < .001).

CONCLUSION

Children with CHD had poorer academic achievement and were more likely to receive special education services than all state students. Results from this study support the need for neurodevelopmental evaluations as standard practice in children with CHD.

Hypoplastic Left Heart Syndrome and Other Shunt-Dependent Single Ventricles

OBJECTIVES

In this review, we discuss the pathophysiology, treatment, and outcomes of patients with the hypoplastic left heart syndrome and other single ventricle variants prior to and following surgery.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Patients with shunted single ventricle physiology are at increased risk for acute hemodynamic decompensation owing to the increased myocardial workload, the dynamic balance between systemic and pulmonary circulations, and the potential for shunt obstruction. Understanding of the physiology and anticipatory management are critical to prevent hemodynamic compromise and cardiac arrest.

Association of Prenatal Diagnosis of Critical Congenital Heart Disease With Postnatal Brain Development and the Risk of Brain Injury

IMPORTANCE

The relationship of prenatal diagnosis of critical congenital heart disease (CHD) with brain injury and brain development is unknown. Given limited improvement of CHD outcomes with prenatal diagnosis, the effect of prenatal diagnosis on brain health may reveal additional benefits.

OBJECTIVE

To compare the prevalence of preoperative and postoperative brain injury and the trajectory of brain development in neonates with prenatal vs postnatal diagnosis of CHD.

DESIGN, SETTING, AND PARTICIPANTS

Cohort study of term newborns with critical CHD recruited consecutively from 2001 to 2013 at the University of California, San Francisco and the University of British Columbia. Term newborns with critical CHD were studied with brain magnetic resonance imaging preoperatively and postoperatively to determine brain injury severity and microstructural brain development with diffusion tensor imaging by measuring fractional anisotropy and the apparent diffusion coefficient. Comparisons of magnetic resonance imaging findings and clinical variables were made between prenatal and postnatal diagnosis of critical CHD. A total of 153 patients with transposition of the great arteries and single ventricle physiology were included in this analysis.

MAIN OUTCOMES AND MEASURES

The presence of brain injury on the preoperative brain magnetic resonance imaging and the trajectory of postnatal brain microstructural development.

RESULTS

Among 153 patients (67% male), 96 had transposition of the great arteries and 57 had single ventricle physiology. The presence of brain injury was significantly higher in patients with postnatal diagnosis of critical CHD (41 of 86 [48%]) than in those with prenatal diagnosis (16 of 67 [24%]) (P = .003). Patients with prenatal diagnosis demonstrated faster brain development in white matter fractional anisotropy (rate of increase, 2.2%; 95% CI, 0.1%-4.2%; P = .04) and gray matter apparent diffusion coefficient (rate of decrease, 0.6%; 95% CI, 0.1%-1.2%; P = .02). Patients with prenatal diagnosis had lower birth weight (mean, 3184.5 g; 95% CI, 3050.3-3318.6) than those with postnatal diagnosis (mean, 3397.6 g; 95% CI, 3277.6-3517.6) (P = .02). Those with prenatal diagnosis had an earlier estimated gestational age at delivery (mean, 38.6 weeks; 95% CI, 38.2-38.9) than those with postnatal diagnosis (mean, 39.1 weeks; 95% CI, 38.8-39.5) (P = .03).

CONCLUSIONS AND RELEVANCE

Newborns with prenatal diagnosis of single ventricle physiology and transposition of the great arteries demonstrate less preoperative brain injury and more robust microstructural brain development than those with postnatal diagnosis. These results are likely secondary to improved cardiovascular stability. The impact of these findings on neurodevelopmental outcomes warrants further study.

Neuropsychological Status and Structural Brain Imaging in Adolescents With Single Ventricle Who Underwent the Fontan Procedure

BACKGROUND

Few studies have described the neuropsychological outcomes and frequency of structural brain or genetic abnormalities in adolescents with single ventricle who underwent the Fontan procedure.

METHODS AND RESULTS

In a cross-sectional, single-center study, we enrolled 156 subjects with single ventricle, mean age 14.5±2.9 years, who had undergone the Fontan procedure. Scores in the entire cohort on a standard battery of neuropsychological tests were compared with those of normative populations or to those of a group of 111 locally recruited healthy adolescents. They also underwent brain magnetic resonance imaging and were evaluated by a clinical geneticist. Genetic abnormalities were definite in 16 subjects (10%) and possible in 49 subjects (31%). Mean Full-Scale IQ was 91.6±16.8, mean Reading Composite score was 91.9±17.2, and mean Mathematics Composite score was 92.0±22.9, each significantly lower than the population means of 100±15. Mean scores on other neuropsychological tests were similarly lower than population norms. In multivariable models, risk factors for worse neuropsychological outcomes were longer total support and circulatory arrest duration at first operation, presence of a genetic abnormality, more operations and operative complications, more catheterization complications, and seizure history. The frequency of any abnormality on magnetic resonance imaging was 11 times higher among Fontan adolescents than referents (66% versus 6%); 19 (13%) patients had evidence of a stroke, previously undiagnosed in 7 patients (40%).

CONCLUSIONS

The neuropsychological deficits and high frequencies of structural brain abnormalities in adolescents who underwent the Fontan procedure highlight the need for research on interventions to improve the long-term outcomes in this high-risk group.

Scoring system for periventricular leukomalacia in infants with congenital heart disease

BACKGROUND

Currently two magnetic resonance imaging (MRI) methods have been used to assess periventricular leukomalacia (PVL) severity in infants with congenital heart disease: manual volumetric lesion segmentation and an observational categorical scale. Volumetric classification is labor intensive and the categorical scale is quick but unreliable. We propose the quartered point system (QPS) as a novel, intuitive, time-efficient metric with high interrater agreement.

METHODS

QPS is an observational scale that asks the rater to score MRIs on the basis of lesion size, number, and distribution. Pre- and postoperative brain MRIs were obtained on term congenital heart disease infants. Three independent observers scored PVL severity using all three methods: volumetric segmentation, categorical scale, and QPS.

RESULTS

One-hundred and thirty-five MRIs were obtained from 72 infants; PVL was seen in 48 MRIs. Volumetric measurements among the three raters were highly concordant (ρc = 0.94-0.96). Categorical scale severity scores were in poor agreement between observers (κ = 0.17) and fair agreement with volumetrically determined severity (κ = 0.26). QPS scores were in very good agreement between observers (κ = 0.82) and with volumetric severity (κ = 0.81).

CONCLUSION

QPS minimizes training and sophisticated radiologic analysis and increases interrater reliability. QPS offers greater sensitivity to stratify PVL severity and has the potential to more accurately correlate with neurodevelopmental outcomes.

Congenital cardiac anomalies and white matter injury

Cardiac abnormalities are the most common birth defects. Derangement of circulatory flow affects many vital organs; without proper supply of oxygenated blood, the brain is particularly vulnerable. Although surgical interventions have greatly reduced mortality rates, patients often suffer an array of neurological deficits throughout life. Neuroimaging provides a macroscopic assessment of brain injury and has shown that white matter (WM) is at risk. Oligodendrocytes and myelinated axons have been identified as major targets of WM injury, but still little is known about how congenital heart anomalies affect the brain at the cellular level. Further integration of animal model studies and clinical research will define novel therapeutic targets and new standards of care to prevent developmental delay associated with cardiac abnormalities.

Twin-reversed arterial perfusion sequence associated with decreased fetal cerebral vascular impedance

OBJECTIVES

Twin-reversed arterial perfusion (TRAP) sequence affects 1% of monochorionic twin pregnancies and is caused by abnormal vascular connections between a pump twin and an acardiac mass. The effects of abnormal vascular connections on cerebral vasculature in the pump twin are unknown. We hypothesize that abnormal cerebral vascular impedance, as assessed by the pulsatility index (PI), is present in pump twins and that fetal intervention alters cerebral impedance.

METHODS

Fetal echocardiograms performed between 2010 and 2013 in pregnancies diagnosed with TRAP (n = 19), recorded at presentation, and uncomplicated monochorionic twin pregnancies (controls, n = 18; 36 fetuses) were analyzed. In all subjects, the middle cerebral artery (MCA)-PI, combined cardiac output (CCO) and cardiothoracic ratio were calculated, and the values for cases and controls were compared.

RESULTS

The mean gestational age at the time of echocardiography was 20 weeks in both groups. MCA-PI was lower in TRAP cases than in controls (1.55 (95% CI, 1.47-1.64) vs 1.74 (95% CI, 1.65-1.82), respectively; P = 0.004). CCO in TRAP cases was mildly elevated for gestational age (199.7 (95% CI, 138.4-261.1) mL/min) compared with that of controls (131.4 (95% CI, 102.2-160.7) mL/min). In six TRAP cases with a second echocardiogram available, the mean MCA-PI increased after intervention, from 1.5 (95% CI, 1.3-1.7) to 1.8 (95% CI, 1.4-2.2).

CONCLUSIONS

TRAP pump twins have lower cerebral vascular impedance than do controls, suggestive of a brain-sparing effect. MCA-PI appeared to increase in a small group of pump twins after intervention. These findings suggest a fetal cerebral autoregulatory response to a high cardiac output state that begins to change after fetal intervention. The long-term implications for neurodevelopmental outcome warrant further study.

The Year in Review

Congenital cardiac anesthesiology is a rapidly expanding field at both ends of the life spectrum. The care of the unborn child with congenital heart disease is becoming highly specialized in regional centers that offer advanced imaging techniques, coordinated specialist care, and potentially fetal interventions. As more children with congenital heart disease survive to adulthood, patients and their health care providers are facing new challenges. The growing volume of publications reflects this expanding field of congenital cardiac anesthesiology. This year in review article highlights some developing trends in the literature.

Minimizing the risk of preoperative brain injury in neonates with aortic arch obstruction

OBJECTIVE

To determine whether prenatal diagnosis lowers the risk of preoperative brain injury by assessing differences in the incidence of preoperative brain injury across centers.

STUDY DESIGN

From 2 prospective cohorts of newborns with complex congenital heart disease studied by preoperative cerebral magnetic resonance imaging, one cohort from the University Medical Center Utrecht (UMCU) and a combined cohort from the University of California San Francisco (UCSF) and University of British Columbia (UBC), patients with aortic arch obstruction were selected and their imaging and clinical course reviewed.

RESULTS

Birth characteristics were comparable between UMCU (n = 33) and UCSF/UBC (n = 54). Patients had a hypoplastic aortic arch with either coarctation/interruption or hypoplastic left heart syndrome. In subjects with prenatal diagnosis, there was a significant difference in the prevalence of white matter injury (WMI) between centers (11 of 22 [50%] at UMCU vs 4 of 30 [13%] at UCSF/UBC; P < .01). Prenatal diagnosis was protective for WMI at UCSF/UBC (13% prenatal diagnoses vs 50% postnatal diagnoses; P < .01), but not at UMCU (50% vs 46%, respectively; P > .99). Differences in clinical practice between prenatally diagnosed subjects at UMCU vs UCSF/UBC included older age at surgery, less time spent in the intensive care unit, greater use of diuretics, less use of total parenteral nutrition (P < .01), and a greater incidence of infections (P = .01). In patients diagnosed postnatally, the prevalence of WMI was similar in the 2 centers (46% at UMCU vs 50% at UCSF/UBC; P > .99). Stroke prevalence was similar in the 2 centers regardless of prenatal diagnosis (prenatal diagnosis: 4.5% at Utrecht vs 6.7% at UCSF/UBC, P = .75; postnatal diagnosis: 9.1% vs 13%, respectively, P > .99).

CONCLUSION

Prenatal diagnosis can be protective for WMI, but this protection may be dependent on specific clinical management practices that differ across centers.

Time to surgery and preoperative cerebral hemodynamics predict postoperative white matter injury in neonates with hypoplastic left heart syndrome

OBJECTIVE

Hypoxic-ischemic white mater brain injury commonly occurs in neonates with hypoplastic left heart syndrome (HLHS). Approximately one half of HLHS survivors will exhibit neurobehavioral symptoms believed to be associated with this injury, although the exact timing of the injury is unknown.

METHODS

Neonates with HLHS were recruited for pre- and postoperative monitoring of cerebral oxygen saturation, cerebral oxygen extraction fraction, and cerebral blood flow using 2 noninvasive optical-based techniques: diffuse optical spectroscopy and diffuse correlation spectroscopy. Anatomic magnetic resonance imaging was performed before and approximately 1 week after surgery to quantify the extent and timing of the acquired white matter injury. The risk factors for developing new or worsened white matter injury were assessed using uni- and multivariate logistic regression.

RESULTS

A total of 37 neonates with HLHS were studied. On univariate analysis, neonates who developed a large volume of new, or worsened, postoperative white matter injury had a significantly longer time to surgery (P=.0003). In a multivariate model, a longer time between birth and surgery, delayed sternal closure, and greater preoperative cerebral blood flow were predictors of postoperative white matter injury. Additionally, a longer time to surgery and greater preoperative cerebral blood flow on the morning of surgery correlated with lower cerebral oxygen saturation (P=.03 and P=.05, respectively) and greater oxygen extraction fraction (P=.05 for both).

CONCLUSIONS

A longer time to surgery was associated with new postoperative white matter injury in otherwise healthy neonates with HLHS. The results suggest that earlier Norwood palliation might decrease the likelihood of acquiring postoperative white matter injury.

Focal necrosis and disturbed myelination in the white matter of newborn infants: a tale of too much or too little oxygen

White matter disease in preterm infants comes along with focal destructions or with diffuse myelination disturbance. Recent experimental work with transgenic mice paves the way for a unifying molecular model for both types of brain injury, placing oxygen sensing by oligodendrocyte precursor cells (OPCs) at the center stage. Mice genetically altered to mimic high local oxygen tension in oligodendroglia lineage cells (via deletion of hypoxia-inducible factor, HIF) develop white matter disease resembling cystic periventricular leukomalacia within the first 7 days of life. Mice in which local hypoxia is mimicked in oligodendroglial cells (via genetic inhibition of HIF decay) display arrested OPC maturation and subsequent hypomyelination, reminiscent of the diffuse white matter disease observed in preterm infants and infants with congenital heart disease. These recent experimental findings on oxygen sensing and myelination are awaiting integration into a clinical framework. Gene regulation in response to hyperoxia or hypoxia, rather than oxidative stress, may be an important mechanism underlying neonatal white matter disease.