Mechanisms of brain injury during infant cardiac surgery

The risk of attention-deficit hyperactivity disorder among children with congenital heart disease: A systematic review and meta-analysis

BACKGROUND

Although current treatments are effective in dealing with congenital heart disease (CHD), non-cardiac comorbidities such as attention-deficit hyperactivity disorder (ADHD) have received widespread attention. The purpose of this systematic review and meta-analysis is to assess the risk of ADHD associated with CHD.

METHODS

The literature search was carried out systematically through eight different databases by the end of September 2022. Either a fixed- or a random-effects model was used to calculate the overall combined risk estimates. The heterogeneity of the studies was assessed by the Cochran Q test and the I2 statistic. Subgroup and sensitivity analyses were used to explore the potential sources of heterogeneity.

RESULTS

Eleven studies were included in this study, which involved a total of 296 741 participants. Our study showed that the children with CHD were at a significantly increased risk of ADHD compared with the reference group (OR = 2.98, 95% CI: 2.18-4.08). The results were moderately heterogeneous. These factors including study design, geographic region and study quality were identified as the first three of the most relevant heterogeneity moderators by subgroup analyses. Sensitivity analysis yielded consistent results. There was no evidence of publication bias.

CONCLUSIONS

The present study suggests that CHD children have a significantly higher risk of ADHD when compared with those without CHD. Early identification and intervention of ADHD is important to reduce its symptoms and adverse effects; therefore, clinicians should increase screening for ADHD in children with CHD and intervene promptly to reduce its effects whenever possible.

Risk Factors of Perioperative Brain Injury in Children Under Two Years Undergoing Coarctation Repair

BACKGROUND

To investigate clinical manifestations and factors of perioperative brain injury (PBI) after surgical repair of coarctation of the aorta (CoA) combined with other heart malformations under cardiopulmonary bypass (CPB) in children under two years.

METHODS

The clinical data of 100 children undergoing CoA repair were retrospectively reviewed between January 2010 and September 2021. Univariate and multivariate analyses were performed to identify factors of PBI development. Hierarchical and K-means cluster analyses were conducted to evaluate the association between hemodynamic instability and PBI.

RESULTS

Eight children developed postoperative complications, and all of them had a favorable neurological outcome one year after surgery. Univariate analysis revealed eight risk factors associated with PBI. Multivariate analysis indicated operation duration (P = 0.04, odds ratio [OR], 2.93; 95% confidence interval [CI], 1.04 to 8.28) and pulse pressure (PP) minimum (P = 0.01; OR, 0.22; 95% CI, 0.06 to 0.76) were independently associated with PBI. The following three parameters emerged for cluster analysis: PP minimum, mean arterial pressure (MAP) dispersion, and systemic vascular resistance (SVR) average. Using cluster analysis, PBI mainly occurred in subgroups 1 (12%, three of 26) and 2 (10%, five of 48). The mean value of PP and MAP in subgroup 1 was significantly higher than in subgroup 2. The mean SVR in subgroup 1 was the highest. The lowest PP minimum, MAP, and SVR were observed in subgroup 2.

CONCLUSION

Lower PP minimum and longer operation duration were independent risk factors for developing PBI in children under two years during CoA repair. Unstable hemodynamics should be avoided during CPB.

Long-term neurodevelopmental effects of intraoperative blood pressure during surgical closure of a septal defect in infancy or early childhood

BACKGROUND

Many children born with congenital heart defects are faced with cognitive deficits and psychological challenges later in life. The mechanisms behind are suggested to be multifactorial and are explained as an interplay between innate and modifiable risk factors. The aim was to assess whether there is a relationship between mean arterial pressure during surgery of a septal defect in infancy or early childhood and intelligence quotient scores in adulthood.

METHODS

In a retrospective study, patients were included if they underwent surgical closure of a ventricular septal defect or an atrial septal defect in childhood between 1988 and 2002. Every patient completed an intelligence assessment upon inclusion, 14-27 years after surgery, using the Wechsler Adult Intelligence Scale Version IV.

RESULTS

A total of 58 patients met the eligibility criteria and were included in the analyses. No statistically significant correlation was found between blood pressure during cardiopulmonary bypass and intelligence quotient scores in adulthood (r = 0.138; 95% CI-0.133-0.389). Although amongst patients with mean arterial pressure < 40 mmHg during cardiopulmonary bypass, intelligence quotient scores were significantly lower (91.4; 95% CI 86.9-95.9) compared to those with mean arterial pressure > 40 mmHg (99.8; 95% CI 94.7-104.9).

CONCLUSIONS

Mean arterial pressure during surgery of ventricular septal defects or atrial septal defects in childhood does not correlate linearly with intelligence quotient scores in adulthood. Although there may exist a specific cut-off value at which low blood pressure becomes harmful. Larger studies are warranted in order to confirm this, as it holds the potential of partly relieving CHD patients of their cognitive deficits.

Increased cerebral mitochondrial dysfunction and reactive oxygen species with cardiopulmonary bypass

OBJECTIVES

Neurodevelopmental injury after cardiac surgery using cardiopulmonary bypass (CPB) for congenital heart defects is common, but the mechanism behind this injury is unclear. This study examines the impact of CPB on cerebral mitochondrial reactive oxygen species (ROS) generation and mitochondrial bioenergetics.

METHODS

Twenty-three piglets (mean weight 4.2 ± 0.5 kg) were placed on CPB for either 1, 2, 3 or 4 h (n = 5 per group) or underwent anaesthesia without CPB (sham, n = 3). Microdialysis was used to measure metabolic markers of ischaemia. At the conclusion of CPB or 4 h of sham, brain tissue was harvested. Utilizing high-resolution respirometry, with simultaneous fluorometric analysis, mitochondrial respiration and ROS were measured.

RESULTS

There were no significant differences in markers of ischaemia between sham and experimental groups. Sham animals had significantly higher mitochondrial respiration than experimental animals, including maximal oxidative phosphorylation capacity of complex I (OXPHOSCI) (3.25 ± 0.18 vs 4-h CPB: 1.68 ± 0.10, P < 0.001) and maximal phosphorylating respiration capacity via convergent input through complexes I and II (OXPHOSCI+CII) (7.40 ± 0.24 vs 4-h CPB: 3.91 ± 0.20, P < 0.0001). At 4-h, experimental animals had significantly higher ROS related to non-phosphorylating respiration through complexes I and II (ETSCI+CII) than shams (1.08 ± 0.13 vs 0.64 ± 0.04, P = 0.026).

CONCLUSIONS

Even in the absence of local markers of ischaemia, CPB is associated with decreased mitochondrial respiration relative to shams irrespective of duration. Exposure to 4 h of CPB resulted in a significant increase in cerebral mitochondrial ROS formation compared to shorter durations. Further study is needed to improve the understanding of cerebral mitochondrial health and its effects on the pathophysiology of neurological injury following exposure to CPB.

Ventricular and total brain volumes in infants with congenital heart disease: a longitudinal study

BACKGROUND

Quantitative MRI techniques help recognize delayed brain development in fetuses with congenital heart disease (CHD). Ventriculomegaly became an early marker of brain dysmaturity.

OBJECTIVE

Evaluate longitudinally the cerebral ventricular and total brain volumes (TBV) in infants with CHD compared to normal neonates: testing the fetal brain dysmaturity and following its progression post operatively.

STUDY DESIGN

Fetal and post-operative MRIs were obtained on fetuses/neonates with CHD requiring invasive intervention within the first month after birth. Volumetric measurement was done with ITK-SNAP and analyzed post-hoc.

RESULTS

Ten cases were evaluated with a significant decrease in ventricular volumes from the fetal to the post-operative neonatal timepoint (p = 0.0297). Infants with HLHS had a significant increase postoperatively in their TBV (p = 0.0396).

CONCLUSIONS

TBV increased post operatively inversely mirrored by the decrement of the ventricular volumes. This could be explained by the establishment an increase of brain blood flow after surgery.

A low incidence of preoperative neurosonographic abnormalities in neonates with heart defects

BACKGROUND AND AIM

To investigate whether neonates with prenatally detected congenital heart defects (CHD) demonstrate cerebral abnormalities on early preoperative cranial ultrasound (CUS), compared to healthy neonates, and to measure brain structures to assess brain growth and development in both groups.

STUDY DESIGN, SUBJECTS AND OUTCOME MEASURES

Prospective cohort study with controls. Between September 2013 and May 2016 consecutive cases of prenatally detected severe isolated CHD were included. Neonatal CUS was performed shortly after birth, before surgery and in a healthy control group. Blinded images were reviewed for brain abnormalities and various measurements of intracranial structures were compared.

RESULTS

CUS was performed in 59 healthy controls and 50 CHD cases. Physiological CUS variants were present in 54% of controls and in 52% of CHD cases. Abnormalities requiring additional monitoring (both significant and minor) were identified in four controls (7%) and five CHD neonates (10%). Significant abnormalities were only identified in four CHD neonates (8%) and never in controls. A separate analysis of an additional 8 CHD neonates after endovascular intervention demonstrated arterial stroke in two cases that underwent balloon atrioseptostomy (BAS). Cerebral measurements were smaller in CHD neonates, except for the cerebrospinal fluid measurements, which were similar to the controls.

CONCLUSIONS

The prevalence of significant preoperative CUS abnormalities in CHD cases was lower than previously reported, which may be partially caused by a guarding effect of a prenatal diagnosis. Arterial stroke occurred only in cases after BAS. As expected, neonates with CHD display slightly smaller head size and cerebral growth.

Structural brain abnormalities in adolescents and young adults with congenital heart defect: a systematic review

AIM

The primary objective of this systematic review is to define and quantify brain structural abnormalities present in adolescents and young adults with complex congenital heart defect (CHD). We also aim to evaluate the extent to which these structural abnormalities are associated with functional outcomes.

METHOD

A search of studies examining brain structure by magnetic resonance imaging in adolescents and young adults with complex CHD was performed in Embase, MEDLINE, and Web of Science. A meta-analysis was conducted to determine the odds of brain abnormalities in young people with CHD. Results not included in the meta-analysis were collated using descriptive statistics.

RESULTS

Two hundred and fifty-four studies were identified through the literature search. Among these, 14 original studies were included in the review. The odds of brain abnormalities in young people with CHD were 7.9 times higher (p<0.001) than in typically developing comparison individuals. Focal and multifocal lesions were the most common types of abnormality (odds ratio 22.5 [p<0.001]). Preliminary evidence from volumetric, cortical, and microstructural integrity measurements suggests that brain abnormalities are associated with poorer neurocognitive outcomes.

INTERPRETATION

This review provides strong evidence that adolescents and young adults with CHD are at increased risk of presenting with structural brain abnormalities and highlights the contribution of advanced quantitative magnetic resonance imaging techniques to identify the subtle but frequent brain alterations in this population. However, more studies are needed to clarify how these abnormalities relate to function.

WHAT THIS PAPER ADDS

There is a high prevalence of brain abnormalities in young people with congenital heart defect (CHD). Brain volumes, cortical measurements, and white matter microstructure are altered in young people with CHD. Brain abnormalities are associated with poorer function in young people with CHD.

Posterior Cerebellar Volume and Executive Function in Young Adults With Congenital Heart Disease

OBJECTIVES

As the number of adolescents and young adults (AYAs) surviving congenital heart disease (CHD) grows, studies of long-term outcomes are needed. CHD research documents poor executive function (EF) and cerebellum (CB) abnormalities in children. We examined whether AYAs with CHD exhibit reduced EF and CB volumes. We hypothesized a double dissociation such that the posterior CB is related to EF while the anterior CB is related to motor function. We also investigated whether the CB contributes to EF above and beyond processing speed.

METHODS

Twenty-two AYAs with CHD and 22 matched healthy controls underwent magnetic resonance imaging and assessment of EF, processing speed, and motor function. Volumetric data were calculated using a cerebellar atlas (SUIT) developed for SPM. Group differences were compared with t tests, relationships were tested with Pearson's correlations and Fisher's r to z transformation, and hierarchical regression was used to test the CB's unique contributions to EF.

RESULTS

CHD patients had reduced CB total, lobular, and white matter volume (d=.52-.99) and poorer EF (d=.79-1.01) compared to controls. Significant correlations between the posterior CB and EF (r=.29-.48) were identified but there were no relationships between the anterior CB and motor function nor EF. The posterior CB predicted EF above and beyond processing speed (ps<.001).

CONCLUSIONS

This study identified a relationship between the posterior CB and EF, which appears to be particularly important for inhibitory processes and abstract reasoning. The unique CB contribution to EF above and beyond processing speed alone warrants further study. (JINS, 2018, 24, 939-948).

Glial fibrillary acidic protein plasma levels are correlated with degree of hypothermia during cardiopulmonary bypass in congenital heart disease surgery

Objectives

Improved congenital heart defect (CHD) operations have reduced operative mortality to 3%. The major concern is now long-term neurological outcomes. We measured plasma glial fibrillary acidic protein (GFAP), an early marker of brain injury, during different phases of cardiopulmonary bypass (CPB), to correlate the increase of GFAP to clinical parameters or specific operative phases.

Methods

We performed a prospective, single-centre, observational study in children undergoing cardiac operations. We studied 69 children with CHD and biventricular heart physiology: 26 had tetralogy of Fallot; 17 transposition of the great arteries; and 26 ventricular/atrial septal defects with or without associated arch defects. GFAP levels were measured by ELISA at different stages of CPB. We recorded clinical and surgical parameters and applied multivariable and logistic regressions to assess which parameters were independent predictors of variations in plasma GFAP.

Results

GFAP increased during CPB and peaked at the end of rewarming. Multivariable regression showed degree of hypothermia as the only significant independent predictor of GFAP increase, adjusted for age, prematurity, type of CHD, cyanosis, aortic cross-clamp time, haemodilution, neurological risk time interval and rewarming rate. Temperature nadir and neurological risk time interval were significant independent predictors of a GFAP value  > 0.46 ng/ml.

Conclusions

Hypothermia degree during CPB is correlated with GFAP plasma increase in children with biventricular heart defects undergoing surgical repair. Rewarming is the most critical CPB phase for GFAP increase. The implication of high plasma GFAP is still under evaluation. Follow-up studies are ongoing to assess the reliability of GFAP as a marker of brain injury and/or as a predictor of neurodevelopmental abnormalities.

Organ-protective effects on the liver and kidney by minocycline in small piglets undergoing cardiopulonary bypass

Cardiopulmonary bypass (CPB) often is required for the operative correction of congenital heart defects in small infants. Unfortunately, CPB is associated with injury of inner organs such as the brain, kidney, lung, and liver. Renal failure and increase in liver enzymes are typical side effects observed after CPB. Here, we investigate whether organ protection of the kidney and liver can be achieved with the application of minocycline, which is known-besides its anti-infective effects-to act as a poly-ADP-ribose-polymerase inhibitor. Twenty-nine 4-week-old Angler Sattelschwein-piglets (8-15 kg) were divided into four groups: control group (n = 8), CPB group (n = 9), minocycline-control group (n = 6), and the minocycline-CPB group (n = 6). CPB groups were thoracotomized and underwent CPB for 120 min (cross-clamp, 90 min; reperfusion, 30 min) followed by a 90-min recovery time. The control groups also were thoracotomized but not connected to CPB. The minocycline group received 4 mg/kg minocycline before and 2 mg/kg after CPB. In the kidneys, CPB histologically resulted in widening of Bowman's capsule, and-mainly in tubules-formation of poly-ADP-ribose, nitrosylation of tyrosine-residues, nuclear translocation of hypoxia-induced factor HIF-1α, and of apoptosis-inducing factor (AIF). In addition, we found significantly less ATP in the kidney and significantly increased plasma urea and creatinine. Similar but gradually attenuated changes were found in the liver together with significantly elevated de-Ritis coefficient. These changes in the kidney and liver were significantly diminished by minocycline (except AIF in the liver which was similar in all groups). In conclusion, CPB causes damage in the kidney and-to a lower degree-in the liver, which can be attenuated by minocycline.

Academic proficiency in children after early congenital heart disease surgery

Children with early surgery for congenital heart disease (CHD) are known to have impaired neurodevelopment; their performance on school-age achievement tests and their need for special education remains largely unexplored. The study aimed to determine predictors of academic achievement at school age and placement in special education services among early CHD surgery survivors. Children with CHD surgery at <1 year of age from January 1, 1998 to December 31, 2003, at the Arkansas Children's Hospital were identified. Out-of-state births and infants with known genetic and/or neurologic conditions were excluded. Infants were matched to an Arkansas Department of Education database containing standardized assessments at early school age and special-education codes. Predictors for achieving proficiency in literacy and mathematics and the receipt of special education were determined. Two hundred fifty-six children who attended Arkansas public schools and who had surgery as infants were included; 77.7 % had either school-age achievement-test scores or special-education codes of mental retardation or multiple disabilities. Scores on achievement tests for these children were 7-13 % lower than those of Arkansas students (p < 0.01). They had an eightfold increase in receipt of special education due to multiple disabilities [odds ratio (OR) 10.66, 95 % confidence interval (CI) 4.23-22.35] or mental retardation (OR 4.96, 95 % CI 2.6-8.64). Surgery after the neonatal period was associated with decreased literacy proficiency, and cardiopulmonary bypass during the first surgery was associated with decreased mathematics proficiency. Children who had early CHD surgery were less proficient on standardized school assessments, and many received special education. This is concerning because achievement-test scores at school age are "real-world" predictors of long-term outcomes.

Brain monitoring in children

Applying scalp sensors in the operating theater, intensive care, or resuscitation scenarios to detect and monitor brain function is achievable, practical, and affordable. The modalities are complex and the output of the monitor needs careful interpretation. The monitor may have technical problems, and a single reading must be considered with caution. These monitors may have a use for monitoring trends in specific situations, but evidence does not support their widespread use. Nevertheless, research should continue to investigate their role. Future techniques and treatments may show that these monitors can monitor brain function and prevent harm.

Cerebral perfusion during cardiopulmonary bypass in children: correlations between near-infrared spectroscopy, temperature, lactate, pump flow, and blood pressure

Near-infrared spectroscopy (NIRS) is a noninvasive modality to monitor regional brain oxygenation (rSO(2) ). In this study, we aimed to investigate the correlation between cerebral rSO(2) and lactate, pump flow, hematocrit, pCO(2) , and mean blood pressure (MBP) during cardiopulmonary bypass (CPB). Between March and September 2011, 50 pediatric patients who underwent congenital heart surgery were enrolled into the study. Ages ranged from 6 days to 168 months (median 14 months). A NIRS sensor (Somanetics 5100B, Troy, MI, USA) was placed on the right forehead of patients. CPB period was divided into five stages: 1-at the beginning of CBP, 2-cooling at 32°C, 3-at final hypothermic temperature, 4-rewarming at 32°C, 5-before weaning from CPB. Data collection included measurements of each parameter at five stages of CPB. Data were analyzed using multivariate analysis within groups and Spearman's correlation to test association between parameters. Lactate levels increased significantly from stage 1 to stage 5 during CPB (P < 0.05). There was no significant correlation between cerebral rSO(2) and MBPs, pump flows, hematocrit, or pCO(2) during CPB. Cerebral rSO(2) levels showed changes between the stages; there was a significant increase during cooling period, compared to stage 1 (P < 0.05). Significant changes during cooling stage did not happen for other parameters. At stage 3, there was a negative correlation between lactate level and MBP. At stage 4, there was no significant change in cerebral rSO(2) levels despite decreased MBP. At the warming stage, low MBPs, but normal rSO(2) values, are observed despite increased pump flows. Increased rSO(2) levels despite insignificant changes at other parameters during the cooling stage of CPB may show that optimal pump flow with adequate intravascular volume may provide effective cerebral perfusion even without changes in MBP. Considering normal rSO(2) values during CPB in this study, it may be speculated that brain protection can be assessed by using NIRS and applying a standard bypass protocol.

Cognitive P300-evoked potentials in school-age children after surgical or transcatheter intervention for ventricular septal defect

BACKGROUND

Some studies have suggested that neurological development may be adversely affected in children with severe coronary heart disease who have undergone long periods of deep hypothermic cardiopulmonary bypass (CPB). Reports of cognitive function in VSD patients in whom surgical repair required only a relatively brief period of CPB are rare. Also, CPB is unnecessary for VSD patients undergoing transcatheter closure. The aim of this study was to assess the cognitive function in patients with ventricular septal defect.

METHODS

A total of 29 patients treated with surgery, and 35 treated with transcatheter closure and their age- and sex-matched best friends completed the cognitive P300 auditory-evoked potentials test and the intelligence test.

RESULTS

The patients and their best friends had normal intelligence quotient; however, the patients had longer P300 peak latencies in cranial frontal lobe and cranial vertex leads (329.2 ± 24.8 and 335.1 ± 20.0 ms) than the healthy controls did (319.1 ± 20.6 and 313 ± 18.2 ms) (P < 0.05). Patients who underwent surgery had longer P300 peak latency in the cranial frontal lobe and cranial vertex leads than did those with transcatheter closure and controls. When cardiopulmonary bypass and aortic clamping were used, the duration was associated with P300 peak latency for patients (P < 0.05).

CONCLUSION

VSD patients, especially those undergoing surgery, showed poor cognitive function, which may be associated with duration of cardiopulmonary bypass or aortic-clamping.

Trajectories of parasympathetic nervous system function before, during, and after feeding in infants with transposition of the great arteries

BACKGROUND

Compromised parasympathetic response to stressors may underlie feeding difficulties in infants with complex congenital heart defects, but little is known about the temporal pattern of parasympathetic response across phases of feeding.

OBJECTIVES

The aim of this study was to describe initial data exploration of trajectories of parasympathetic response to feeding in 15 infants with surgically corrected transposition of the great arteries and to explore the effects of feeding method, feeding skill, and maternal sensitivity on trajectories.

METHOD

In this descriptive, exploratory study, parasympathetic function was measured using high-frequency heart rate variability (HF HRV), feeding skill was measured using the Early Feeding Skills assessment, and maternal sensitivity was measured using the Parent-Child Early Relational Assessment. Data were collected before, during, and after feeding at 2 weeks and 2 months of age. Trajectories of parasympathetic function and relationships with possible contributing factors were examined graphically.

RESULTS

Marked between-infant variability in HF HRV across phases of feeding was apparent at both ages, although it was attenuated at 2 months. Four patterns of HF HRV trajectories across phases of feeding were identified and associated with feeding method, feeding skill, and maternal sensitivity. Developmental increases in HF HRV were apparent in most breast-fed, but not bottle-fed, infants.

DISCUSSION

This exploratory data analysis provides critical information in preparation for a larger study in which varying trajectories and potential contributing factors can be modeled in relationship to infant outcomes. Findings support inclusion of feeding method, feeding skill, and maternal sensitivity in modeling parasympathetic function across feeding.

The registry and follow-up of complex pediatric therapies program of Western Canada: a mechanism for service, audit, and research after life-saving therapies for young children

Newly emerging health technologies are being developed to care for children with complex cardiac defects. Neurodevelopmental and childhood school-related outcomes are of great interest to parents of children receiving this care, care providers, and healthcare administrators. Since the 1970s, neonatal follow-up clinics have provided service, audit, and research for preterm infants as care for these at-risk children evolved. We have chosen to present for this issue the mechanism for longitudinal follow-up of survivors that we have developed for western Canada patterned after neonatal follow-up. Our program provides registration for young children receiving complex cardiac surgery, heart transplantation, ventricular assist device support, and extracorporeal life support among others. The program includes multidisciplinary assessments with appropriate neurodevelopmental intervention, active quality improvement evaluations, and outcomes research. Through this mechanism, consistently high (96%) follow-up over two years is maintained.

Postoperative encephalopathy with choreoathetosis

Since the 1980s, survival of children with CHD has increased significantly with the introduction of new surgical techniques that incorporate cardiorespiratory arrest (CRA), extracorporeal circulation (ECC), and deep hypothermia. However, an increase in survival has been associated with an increase in recognized postoperative neurological complications. Postoperative encephalopathy with choreoathetosis, also known as "postpump chorea", is one of these well-defined neurological complications and was first reported in 1961. Postpump chorea is considered one of the most devastating neurological complications following cardiac surgery. However, the exact etiology and pathophysiology of this complication is unknown. Several factors may contribute to the postoperative development of choreoathetoid movements, including deep hypothermia (core body temperature < 20ºC) with total circulatory arrest, use of cardiopulmonary bypass, and variability in blood pH and PaCO(2) resulting in fluctuations in cerebral blood flow. The length of time children are affected by choreoathetoid movements and long-term neurological outcome in these children varies and largely depends upon the form of postoperative encephalopathy that they develop, described as either mild or severe. Several groups suggest that age at time of surgery plays a role in the risk of developing postpump chorea, with a tendency for older children to develop the severe persistent form.

A systematic review of motor and cognitive outcomes after early surgery for congenital heart disease

CONTEXT

Brain injury is the most common long-term complication of congenital heart disease requiring surgery during infancy. It is clear that the youngest patients undergoing cardiac surgery, primarily neonates and young infants, are at the greatest risk for brain injury. Developmental anomalies sustained early in life have lifelong repercussions.

OBJECTIVE

We conducted a systematic review to examine longitudinal studies of cognitive and/or motor outcome after cardiac surgery during early infancy.

METHODS

Electronic searches were performed in Medline, the Cumulative Index to Nursing and Allied Health Literature (Cinahl), and Embase (1998-2008). The search strategy yielded 327 articles, of which 65 were reviewed. Eight cohorts provided prospective data regarding the cognitive and/or motor outcome of infants who had undergone surgery for congenital heart disease before 6 months of age. Two authors, Ms Snookes and Dr Gunn, independently extracted data and presented results according to 3 subgroups for age of follow-up: early development (1 to <3 years); preschool age (3-5 years); and school age (>5 to 17 years). Weighted analysis was undertaken to pool the results of studies when appropriate.

RESULTS

All of the identified studies reported results of the Bayley Scales of Infant Development for children younger than the age of 3. Outcome data as reported by the Bayley Scales were combined for infants assessed at 1 year of age, revealing a weighted mean Mental Development Index of 90.3 (95% confidence interval: 88.9-91.6) and Psychomotor Development Index of 78.1 (95% confidence interval: 76.4-79.7). Additional analysis was limited by a lack of data at preschool and school age.

CONCLUSIONS

With this review we identified a limited number of prospective studies that systematically addressed outcome in patients at the highest risk. These studies consistently revealed cognitive and motor delay in children after cardiac surgery during early infancy. Additional investigation is required to ascertain the consequences of such impairment during later childhood and into adult life.

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

BACKGROUND

New intraparenchymal brain injury on magnetic resonance imaging is observed in 36% to 73% of neonates after cardiac surgery with cardiopulmonary bypass. Brain immaturity in this population is common. We performed brain magnetic resonance imaging before and after neonatal cardiac surgery, using a high-flow cardiopulmonary bypass protocol, hypothesizing that brain injury on magnetic resonance imaging would be associated with brain immaturity.

METHODS

Cardiopulmonary bypass protocol included 150 mL . kg(-1) . min(-1) flows, pH stat management, hematocrit > 30%, and high-flow antegrade cerebral perfusion. Regional brain oxygen saturation was monitored, with a treatment protocol for regional brain oxygen saturation < 50%. Brain magnetic resonance imaging, consisting of T1-, T2-, and diffusion-weighted imaging, and magnetic resonance spectroscopy were performed preoperatively, 7 days postoperatively, and at age 3 to 6 months.

RESULTS

Twenty-four of 67 patients (36%) had new postoperative white matter injury, infarction, or hemorrhage, and 16% had new white matter injury. Associations with preoperative brain injury included low brain maturity score (P = .002). Postoperative white matter injury was associated with single-ventricle diagnosis (P = .02), preoperative white matter injury (P < .001), and low brain maturity score (P = .05). Low brain maturity score was also associated with more severe postoperative brain injury (P = .01). Forty-five patients had a third scan, with a 27% incidence of new minor lesions, but 58% of previous lesions had partially or completely resolved.

CONCLUSIONS

We observed a significant incidence of both pre- and postoperative magnetic resonance imaging abnormality and an association with brain immaturity. Many lesions resolved in the first 6 months after surgery. Timing of delivery and surgery with bypass could affect the risk of brain injury.

A new look at outcomes of infants with congenital heart disease

This article provides an overview of a longitudinal study on a cohort of 131 newborns and young infants with congenital heart defects who required open heart surgery. The rationale for the study design is provided as well as a summary of the procedures used to evaluate these children prior to surgery, at discharge after surgery, 12-18 months later, and at 5 years of age. Results demonstrate that a substantial proportion of these infants had neurologic and developmental abnormalities prior to surgical repair. Developmental delays were common in children with both cyanotic and acyanotic heart defects, and these deficits persisted to school entry. A number of medical, surgical, demographic and environmental factors were significantly associated with developmental outcomes suggesting a multifactorial etiology to brain injury. Limited educational and rehabilitation resources for this cohort at early school age suggests that service needs may need to be more carefully planned for this high-risk population. Lessons learnt from this prospective study are highlighted as well as future directions for research and clinical practice.

Five-year neurocognitive and health outcomes after the neonatal arterial switch operation

OBJECTIVES

We sought to assess the 5-year neurocognition and health of an interprovincial inception cohort undergoing the arterial switch operation for transposition of the great arteries.

METHODS

Sixty-nine consecutive neonates had operations from 1996-2003 with full-flow cardiopulmonary bypass and selective deep hypothermic circulatory arrest. Outcomes were recorded at 58 +/- 9 months of age. Univariate and multivariate analyses were used to identify outcome predictors, including surgical subtype and preoperative, operative, and postoperative variables.

RESULTS

There was 1 (1.5%) operative death. Two children were lost to follow-up, and 1 was excluded because of postdischarge meningitis. Outcomes are reported for 65 survivors. Two (3%) children have cerebral palsy, and 7 (11%) have language disorders, 4 of whom also meet the criteria for autism spectrum disorder. Two of the 4 children with autism have an affected older sibling. Of the 61 children without autism, scores approach those of peers, with a full-scale intelligence quotient of 97 +/- 16, a verbal intelligence quotient of 97 +/- 18, a performance intelligence quotient of 96 +/- 15, and a visual-motor integration score of 95 +/- 16. Mother's education, birth gestation or weight, and postoperative plasma lactate values account for 21% to 32% of the variance of these scores. Septostomy adds 7% to the variance of visual-motor integration scores.

CONCLUSIONS

Most preschool children do well after surgical correction for transposition of the great arteries, including complex forms. Potentially modifiable variables include high preoperative plasma lactate levels and septostomy. A minority of children were given diagnoses of language disorders, including autism, in which familial factors likely contribute to outcome.

Developmental and functional outcomes at school entry in children with congenital heart defects

OBJECTIVE

To describe developmental and functional outcomes of children with congenital heart defects (CHDs) at school entry after open heart surgery.

STUDY DESIGN

Infants with CHDs who underwent surgical repair in infancy were recruited and assessed prospectively for developmental progress. At 5 years of age (64.2 +/- 11.3 months), 94 subjects were evaluated in a blind fashion by using a variety of standardized measures.

RESULTS

Mean IQ scores were in the low average range (90-94). Receptive language was in the average range (103.6 +/- 14.4). Behavioral difficulties were common (27.1%), with internalizing problems being more frequent. Functional limitations in socialization (93.0 +/- 17.1), daily living skills (94.6 +/- 16.4), communication (90.0 +/- 14.1), and adaptive behavior (92.1 +/- 15.8) were noted in 11% to 17% of children. With the Functional Independence Measure for Children, 20% to 22% of subjects were more dependent than their peers in self-care and social cognition, although few (4.5%) had mobility restrictions. Predictors of developmental and functional limitations included: abnormal postoperative neurologic examination, microcephaly, deep hypothermic circulatory arrest time, palliation, acyanotic heart lesion, age at surgery, and maternal education.

CONCLUSIONS

After infant open-heart surgery, children with CHDs may exhibit a range of developmental difficulties at school entry that enhances risk for learning challenges and decreased social participation.

Perioperative neuroprotective strategies

Long-term neurodevelopmental impairment is common in newborns and infants undergoing corrective or palliative congenital heart surgery. The etiologies of neurodevelopmental morbidity in these children are multifactorial and include prenatal, preoperative, intraoperative, and postoperative factors. Perioperative neurologic monitoring is thought to be integral to prevention or rescue from adverse neurologic events. Recent advances in perfusion techniques for congenital heart surgery now ensure adequate cerebral O(2) delivery during all phases of cardiopulmonary bypass. Periventricular leukomalacia and other serious neurologic injury can be minimized by an optimized perfusion strategy of continuous high-flow, high hematocrit cardiopulmonary bypass, minimal use of deep hypothermic circulatory arrest, antegrade cerebral perfusion during aortic arch reconstruction, pH-stat blood gas strategy, and cerebral monitoring with NIRS and trans-cranial Doppler. Because there is evidence that brain injury can also occur in the prenatal, preoperative, and postoperative periods, improved strategies to prevent injury in these arenas are much needed. Extensive further clinical investigation is warranted to identify neuroprotective management strategies for the operating room and intensive care unit to preserve neurologic function and optimize long-term neurodevelopmental outcomes in children with congenital heart disease.

A clinical evaluation of the Dideco Kids D100 neonatal oxygenatora

In August 2006, Duke University Perfusion Services had the opportunity to be the first institution in the United States to clinically evaluate the Dideco D100 Neonatal Oxygenator. The device was used on six pediatric patients to facilitate correction or palliation of their cardiac defects, which included two arterial switch operations, two truncus arteriosus repairs, one stage 1 Norwood and one repair of total anomalous pulmonary venous return. The average patient weight was 3.1 kg. The average cardiopulmonary bypass(CPB) time was 135 minutes and the average cross-clamp time was 61 minutes. Arterial and venous blood gasses were drawn and used to calculate oxygen transfer. The average oxygen transfer was 14.8 ± 10.3 ml/O2/min. The Dideco D100 Oxygenator is the first oxygenation device designed specifically for neonates. The Dideco D100 is a microporous hollow-fiber device. It has a static priming volume of 31 ml and a maximum rated flow of 700 ml/min. The integral hard-shell venous reservoir has a minimum operating level of 10 ml and a reservoir capacity of 500 ml. For this evaluation, the Dideco Kids D100 Neonatal Oxygenator performed adequately on patients weighing up to 5 kg. This device provides an excellent first step towards offering very small children appropriate circuitry without having to sacrifice safety or performance.

Neurology of congenital heart disease: insight from brain imaging

Understanding of the specific pathophysiology of acquired brain injury in infants with CHD will help optimise treatment and brain protection strategies

Long-term behavior and quality of life after corrective cardiac surgery in infancy for tetralogy of Fallot or ventricular septal defect

The objective of this study was to evaluate behavior and quality of life in children after corrective cardiac surgery in infancy. Twenty cyanotic (tetralogy of Fallot) and 20 acyanotic children (ventricular septal defect), operated at a mean age of 0.7 years with deep hypothermic circulatory arrest (DHCA) and low-flow cardiopulmonary bypass (CPB), were assessed at a mean age of 7.4 years by the Child Behavior Checklist (CBCL) and the German KINDL. Test results were related to perioperative and neurodevelopmental outcome. Compared to healthy children and not significantly different between the groups, internalizing and externalizing problems were elevated, school performance and total competence were reduced, and self- and parent-reported quality of life was not reduced. Parent-reported problems and reduced physical status were correlated with longer durations of DHCA and CPB. Internalizing and externalizing problems, reduced school competence, and reduced self-esteem were associated with reduced endurance capacity. Externalizing problems were related to reduced gross motor function. Poor school competence was related to reduced intelligence and academic achievement. Children with preoperative hypoxemia in infancy due to cyanotic cardiac defects are not at significantly higher risk for behavioral problems and reduced quality of life than those with acyanotic heart defects. The risk of long-term psychosocial maladjustment after corrective surgery in infancy is increased compared to that for normal children and related to the presence of neurodevelopmental dysfunction.

Mortality after neonatal cardiac surgery: Prediction from mean arterial pressure after rewarming in the operating room

OBJECTIVE

To examine the predictive contribution of mean arterial pressure after rewarming to > or =34 degrees C in the operating room to mortality after cardiac surgery in infants < or =6 weeks old.

METHODS

In this prospective inception cohort study, 70 consecutive infants who had open cardiac surgery with deep hypothermic circulatory arrest when < or =6 weeks old in the years 1996 to 1999 had follow-up to 5 years of age. Demographic, preoperative, operative, and postoperative variables were recorded prospectively. The previously unexplored variables of lowest mean arterial pressure in the operating room after rewarming to 34 degrees C were recorded retrospectively from anesthesia records. Predictor variables for death were examined using univariate and multivariate analyses.

RESULTS

Deep hypothermic circulatory arrest time, re-cardiopulmonary bypass in the operating room, duration of mean arterial pressure below 40, 35, 30, and 25 mm Hg after rewarming in the operating room, time for lactate to return to < or =2 mmol/L postoperatively, and cardiopulmonary resuscitation were significantly associated with death at 1 and 5 years of age on univariate analysis. Multivariate stepwise forward logistic regression analysis found the duration of mean arterial pressure after rewarming below 30 mm Hg (odds ratio 1.094; 95% confidence interval 1.033-1.158) and cardiopulmonary resuscitation (odds ratio 13.800, 95% CI 3.062-62.194) were significant predictors of death by 5 years of age. Stepwise multiple regression using pre- and intraoperative variables accounted for 30.1% of the variability related to mean arterial pressure < or =30 mm Hg after rewarming.

CONCLUSION

In these infants, low mean arterial pressure after rewarming in the operating room, even for brief times, is significantly associated with death.

Neurodevelopmental and neuroradiologic outcomes in patients with univentricular heart aged 5 to 7 years: Related risk factor analysis

OBJECTIVE

Despite improved survival and neurodevelopmental outcome, children with hypoplastic left heart syndrome and other forms of univentricular heart remain at increased risk for cognitive, motor, and other neurologic deficits.

METHODS

We examined 27 children with hypoplastic left heart syndrome or other forms of univentricular heart at a median age of 5.70 years (range 4.99-7.51 years) and performed brain computed tomography or magnetic resonance imaging on 20. Possible risk factors were correlated with outcome.

RESULTS

Mean full-scale IQ among patients with hypoplastic left heart syndrome was 86.7; that among patients with other forms of univentricular heart was 89.1, with both differing significantly from the expected population mean (P = .015 and P = .029, respectively). Cerebral palsy was diagnosed in 1 of 7 patients with hypoplastic left heart syndrome and 2 of 20 with other forms of univentricular heart. Brain computed tomography or magnetic resonance imaging revealed ischemic changes and infarcts or atrophy in 5 of 8 patients who had undergone the Norwood procedure and in 2 of 12 of those who had not (P = .062). Abnormal computed tomographic findings correlated significantly with lower full-scale IQ (P = .045) and verbal IQ (P = .02). In the multiple linear regression model, diuresis the third day after the primary operation and cardiopulmonary bypass time in the bidirectional Glenn operation correlated significantly with the primary outcome of full-scale IQ.

CONCLUSION

In children with univentricular heart, intellectual and neurologic deficits are common. Perioperative and postoperative risk factors related to the primary phase and bidirectional Glenn operation contribute to these deficits.

Attentional Dysfunction in Children After Corrective Cardiac Surgery in Infancy

BACKGROUND

Attentional dysfunction in children after corrective cardiac surgery in infancy has rarely been evaluated and is the topic of the present work.

METHODS

Forty unselected children, 20 with tetralogy of Fallot and hypoxemia and 20 with ventricular septal defect and cardiac insufficiency, operated on at a mean age 0.7 (SD 0.3) years with deep hypothermic circulatory arrest and low flow cardiopulmonary bypass, were evaluated at mean age 7.4 (SD 1.6) years by the computerized form of the Attention Network Test providing performance measures of three networks of attention: alerting, orienting, and executive control. Parental ratings of attentional dysfunction were derived from the Child Behavior Checklist. Results were compared with healthy controls, between patient groups, and correlated with perioperative risk factors and current neurodevelopmental status.

RESULTS

Executive control was reduced in the tetralogy of Fallot group, alerting and orienting were found normal and not different between patient groups. Durations of aortic cross clamping inversely correlated with orienting; durations of cardiopulmonary bypass correlated with mean reaction time and inversely correlated with executive control. Motor function and acquired abilities correlated with executive control and orienting. Parent-reported problems on the Child Behavior Checklist inversely correlated with executive control and mean accuracy.

CONCLUSIONS

Children with preoperative hypoxemia in infancy due to cyanotic cardiac defects are at increased risk for attentional dysfunction in the field of executive control, compared with normal children and with those who have acyanotic heart defects. Besides unfavorable perioperative influences, preoperative hypoxemia is considered responsible for additional damage to the highly oxygen sensitive regions of the prefrontal cortex and striate body assumed to be associated with the executive control network of attention.

Cerebral oxygenation during hypoxia and resuscitation by using near-infrared spectroscopy in newborn piglets

BACKGROUND

Hypoxic events and cardiac arrest may cause brain damage in critical infants. This study investigated cerebral tissue oxygenation and oxygen extraction in a piglet model of hypoxic events, cardiac arrest and effects of resuscitation.

METHODS

For the hypoxia experiment, anesthetized newborn piglets were randomized to a hypoxia group (n = 8) with decreasing ventilatory rate to 0, and a control group (n = 8) with no hypoxic conditions. Regional cerebral tissue oxygen saturation (rScO2, detected by near-infrared spectroscopy) and oxygen saturation were recorded every 5 minutes for 100 minutes. Fractional cerebral tissue oxygen extraction (FTOE) was calculated as (arterial oxygen saturation [SaO2] - rScO2)/SaO2. For the resuscitation experiment, animals were grouped as hypoxia-no CPR (n = 4), control-no CPR (n = 4), and control-CPR (n = 4) after cardiac arrest. Standard cardiopulmonary resuscitation (CPR) was performed on the control-CPR group and observed for 30 minutes.

RESULTS

Immediate and significant changes in rScO2, and gradual changes in FTOE were observed during the hypoxia experiment. In the resuscitation experiment, no significant differences in rScO2 were found between groups. However, the highest FTOE was observed in the control-CPR group.

CONCLUSION

Noninvasive monitoring of rScO2 and evaluating FTOE changes during hypoxia and resuscitation may help clinicians evaluate brain tissue oxygenation and viability.

Monitoring the brain before, during, and after cardiac surgery to improve long-term neurodevelopmental outcomes

Innovation in surgical and medical management of cardiac disease has generated a dramatic improvement in operative survival. Along with these favourable results in terms of survival is the heightened awareness of neurologic complications, which often become evident beyond the early postoperative period. A large, multicentre prospective study found serious neurologic injury occurs in about one-twentieth of patients after myocardial revascularization in adults.1More subtle evidence of persistent cognitive decline and functional impairment has been shown to occur in over two-fifths of such patients.2Acute neurologic abnormalities are reported in up to one-fifth of infants and children who undergo cardiac surgery.3–6Lasting impairments in cognitive, motor, and expressive functioning have been reported in up to three-fifths of children who have undergone complex cardiac surgery during infancy.7Specifically, gross and fine motor delays, visual-spatial problems, language deficits and long-term emotional and behavioural problems have been found.8–13

Intellectual development of infants, children and adolescents with congenital heart disease

Cardiac disease is the most common congenital defect in children, affecting between 3 and 10 in every 1000 live births. While significant advances in medical and surgical management have resulted in increasing numbers of survivors, it is also recognized that there is a growing population of children living with neurological impairment and lowered intellectual function. The aetiology of such impairment is multi-factorial and hypoxia is one of the factors involved. This article provides an overview of the effects of hypoxia on the intellectual development of infants, children and adolescents with congenital heart disease.

Pyramidal tract maturation after brain injury in newborns with heart disease

OBJECTIVE

Our objective was to quantify white matter tract development in term newborns with congenital heart disease, a population at high risk for perioperative brain injury, using magnetic resonance imaging diffusion tensor tractography (DTT).

METHODS

Twenty-five newborns with congenital heart disease were imaged before and after surgery, with a median of 2 weeks between serial magnetic resonance imaging examinations. DTT was performed to segment bilateral pyramidal tracts using semiautomated fiber tracking software, and manual region of interest measurements were taken for comparison.

RESULTS

Significant maturational rates of increasing fractional anisotropy (median, 4.4% per week) and decreasing mean diffusivity (D(av)) (median, -2.0% per week) in the pyramidal tract were measured in infants without brain injury. Fractional anisotropy maturation rates were highest in newborns with normal scans, intermediate (median, 2.4% per week) in those with postoperative injury, and lowest (median, 0.9% per week) in those with preoperative injury, indicating a significant trend across brain injury groups (p = 0.015). D(av) maturation rates did not differ across injury groups (p = 0.15). Manual region of interest measures showed greater variability in serial measurements, and no significant differences were identified between injury groups, suggesting that DTT may provide more sensitive measures.

INTERPRETATION

DTT is feasible in term newborns and may help to characterize abnormal white matter tract development following acquired brain injury.

Long-Term Neurodevelopmental Outcome and Exercise Capacity After Corrective Surgery for Tetralogy of Fallot or Ventricular Septal Defect in Infancy

BACKGROUND

The purpose of this prospective study was to assess whether neurodevelopmental status and exercise capacity of children 5 to 10 years after corrective surgery for tetralogy of Fallot or ventricular septal defect in infancy was different compared with normal children and influenced by the preoperative condition of hypoxemia or cardiac insufficiency.

METHODS

Forty unselected children, 20 with tetralogy of Fallot and hypoxemia and 20 with ventricular septal defect and cardiac insufficiency, operated on with combined deep hypothermic circulatory arrest and low flow cardiopulmonary bypass at a mean age of 0.7 +/- 0.3 years (mean +/- SD), underwent, at mean age 7.4 +/- 1.6 years, standardized evaluation of neurologic status, gross motor function, intelligence, academic achievement, language, and exercise capacity. Results were compared between the groups and related to preoperative, perioperative, and postoperative status and management.

RESULTS

Rate of mild neurologic dysfunction was increased compared with normal children, but not different between the groups. Exercise capacity and socioeconomic status were not different compared with normal children and between the groups. Compared with the normal population, motor function, formal intelligence, academic achievement, and expressive and receptive language were significantly reduced (p < 0.01 to p < 0.001) in the whole group and in the subgroups, except for normal intelligence in ventricular septal defect patients. Motor dysfunction was significantly higher in the Fallot group compared with the ventricular septal defect group (p < 0.01) and correlated with neurologic dysfunction, lower intelligence, and reduced expressive language (p < 0.05 each). Reduced New York Heart Association functional class was correlated with lower exercise capacity and longer duration of cardiopulmonary bypass (p < 0.05 each). Reduced socioeconomic status significantly influenced dysfunction in formal intelligence (p < 0.01) and academic achievement (p < 0.05). Preoperative risk factors such as prenatal hypoxia, perinatal asphyxia, and preterm birth, factors of perioperative management such as cardiac arrest, lowest nasopharyngeal temperature, and age at surgery, and postoperative risk factors as postoperative cardiocirculatory insufficiency and duration of mechanical ventilation were not different between the groups and had no influence on outcome. Degree of hypoxemia in Fallot patients and degree of cardiac insufficiency in ventricular septal defect patients did not influence the outcome within the subgroups.

CONCLUSIONS

Children with preoperative hypoxemia in infancy are at higher risk for motor dysfunction than children with cardiac insufficiency. Corrective surgery in infancy for tetralogy of Fallot or ventricular septal defect with combined circulatory arrest and low flow bypass is associated with reduced neurodevelopmental outcome, but not with reduced exercise capacity in childhood. In our experience, the general risk of long-term neurodevelopmental impairment is related to unfavorable effects of the global perioperative management. Socioeconomic status influences cognitive capabilities.

Long-term neuromotor outcome at school entry of infants with congenital heart defects requiring open-heart surgery

OBJECTIVES

Increased survival in infants with complex congenital heart defects (CHDs) has resulted in greater focus on morbidity. This prospective study was conducted to investigate whether or not neuromotor impairments evident acutely persist long-term.

STUDY DESIGN

A total of 94 infants with CHD were reassessed at school entry (age 64.2 +/- 11.3 months) by blinded examiners using the Peabody Developmental Motor Scale and neurologic examination.

RESULTS

Neurologic abnormalities were noted in 28.4% of the subjects, with hypotonia and developmental delay most commonly observed. Microcephaly was documented in 15.4% of subjects, with head circumference >50th percentile in only 14.1%. Mean gross and fine motor quotients were shifted downward (82.7 +/- 12.3 and 86.2 +/- 16.3, respectively), and gross and fine motor delays were prevalent (49.4% and 39.0%, respectively). Severe disability was rare (<5%). Predictors of neurologic impairment included type of surgery (palliative/corrective), abnormal postoperative neurologic examination, and presence of microcephaly at initial surgery. Gross motor delay was more likely if palliated. Deep hypothermic circulatory arrest time, palliative surgery, microcephaly, and number of hospitalizations were associated with fine motor delay.

CONCLUSIONS

Neurologic impairments and motor delay are common in survivors of open-heart surgery, persisting to age of school entry. Early indicators of medical complications and acute neurologic compromise are associated with increased risk. Early identification and intervention may optimize performance in those at risk.

Electroencephalographic changes after pediatric cardiac surgery with cardiopulmonary bypass: is slow wave activity unfavorable?

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) is frequently associated with neurologic deficits. We describe the postoperative EEG changes, assess their possible causes, and evaluate their relevance to neurologic outcome. Thirty-one children and five neonates with congenital heart disease were included. EEG recording started after intubation and continued until 22-96 h after CPB. In addition to conventional analysis, spectral analysis was performed for occipital and frontal electrodes, and differences between pre- and postoperative delta power (delta-deltaP) were calculated. Maximum values of occipital delta-deltaP that occurred within 48 h after CPB were correlated with clinical variables and with perioperative markers of oxidative stress and inflammation. Occipital delta-deltaP correlated with frontal delta-deltaP, and maximum delta-deltaP correlated with conventional rating. Distinct rise of deltaP was detected in 18 of 21 children without any acute or long-term neurologic deficits but only in five of 10 children with temporary or permanent neurologic deficits. Furthermore, maximally registered delta-deltaP was inversely associated with duration of CPB and postoperative ventilation. Maximal delta-deltaP was also inversely associated with the loss of plasma ascorbate (as an index of oxidative stress) and plasma levels of IL-6 and IL-8. Slow wave activity frequently occurs within 48 h after CPB. However, our data do not support the notion that EEG slowing is associated with adverse neurologic outcome. This is supported by the fact that EEG slowing was associated with less oxido-inflammatory stress.

Monitoring of cerebral oxygenation during hypoxic gas management in congenital heart disease with increased pulmonary blood flow

In the preoperative management of congenital heart disease (CHD) with increased pulmonary blood flow, hypoxic gas management to control pulmonary blood flow is useful. However, the cerebral oxygenation state has rarely been studied, and there is concern about neurologic development. In eight infants with CHD accompanied by increased pulmonary blood flow, hypoxia was induced after a 1-h baseline period in room air (FiO2, 0.21). The infants were simultaneously monitored in both the front-temporal region and the right-brachial region for 90 min using near-infrared spectroscopy (NIRS). The minimum SaO2 (pulse oximetry) after hypoxic gas administration was 80.8 +/- 2.9% when the minimum FiO2 was 16.2 +/- 1.1%. With a decrease in SaO2, oxy-Hb (O2Hb) decreased and total Hb [cHb: O2Hb + deoxy-Hb (HHb)] increased in both regions in the majority of infants. HHb increased in both regions with a decrease in SaO2. The maximum change in the tissue oxygenation index (TOI: O2Hb/cHb x 100) was -8.3 +/- 2.6% in the front-temporal region and -3.6 +/- 2.3% in the right-brachial region. Cerebral oxygenation decreased despite an increase in cerebral blood flow during hypoxic gas management. The change in TOI was < or =10% when the SaO2 was > or =80%. Safer control of SaO2 should be maintained over 80% for hypoxia management in CHD based on the results of the present study.

Cerebral oxygen balance is impaired during repair of aortic coarctation in infants and children

OBJECTIVE

During repair of aortic coarctation through a left thoracotomy without cardiopulmonary bypass, clamping the proximal transverse aortic arch occludes antegrade flow to the left carotid and vertebral arteries. It is assumed that flow through the right carotid and vertebral arteries is adequate for cerebral perfusion. The study objective is to determine whether aortic occlusion impairs left hemispheric cerebral oxygen balance measured by near-infrared spectroscopy.

METHODS

In 18 children having repair of aortic coarctation, we measured the maximum change and integral for hemoglobin D (difference of oxyhemoglobin and deoxyhemoglobin), total oxygenation index, and the redox state of cytochrome aa3. Thirteen subjects had recordings from the left hemisphere to test the hypothesis that aortic occlusion impairs left hemispheric oxygen balance. Five subjects had recordings from the right hemisphere for comparison.

RESULTS

After aortic clamping, a significant decrease in hemoglobin D was observed in recordings from the left hemisphere compared with those from the right hemisphere (P = .03, maximum change in hemoglobin D). Total oxygenation index and cytochrome aa3 were generally preserved. There was an inverse linear relationship for the change in hemoglobin D during clamp application and after removal (Spearman rho = -0.74), with increased hemoglobin D after clamp removal in those subjects with the greatest decrease of hemoglobin D during arch occlusion. Linear regression analysis identified nitroprusside administration as significantly associated with a decrease in hemoglobin D (P < .001).

CONCLUSIONS

Significant impairment in left hemispheric cerebral oxygen balance was identified during arch clamping. The neurodevelopmental significance of impaired cerebral oxygen balance detected by near-infrared spectroscopy during aortic coarctation repair remains to be elucidated.

Academic performance and behavioral difficulties after neonatal and infant heart surgery

Although advances in medical and surgical arenas have allowed the ability to "mend" children born with congenital heart disease, the increasing number of survivors has created a growing cohort of children with potential academic difficulties. This article reviews the current understanding of the midterm neurologic outcomes of children who underwent neonatal and infant cardiac surgery. Lesions including transposition of great arteries, tetralogy of Fallot, hypoplastic left heart syndrome, total anomalous pulmonary venous connection, and single ventricle lesions requiring Fontan palliation or cardiac transplantation are discussed.

Neurological Monitoring for Congenital Heart Surgery

The incidence of neurological complications after pediatric cardiac surgery ranges from 2% to 25%. The causes are multifactorial and include preoperative brain malformations, perioperative hypoxemia and low cardiac output states, sequelae of cardiopulmonary bypass, and deep hypothermic circulatory arrest. Neurological monitoring devices are readily available and the anesthesiologist can now monitor the brain during pediatric cardiac surgery. In this review we discuss near-infrared cerebral oximetry, transcranial Doppler ultrasound, and electroencephalographic monitors for use during congenital heart surgery. After review of the basic principles of each monitoring modality, we discuss their uses during pediatric heart surgery. We present evidence that multimodal neurological monitoring in conjunction with a treatment algorithm may improve neurological outcome for patients undergoing congenital heart surgery and present one such algorithm.

Periventricular leukomalacia following neonatal and infant cardiac surgery

The dramatic reduction in surgical mortality following repair of congenital heart defects has been accompanied by increasing recognition of adverse neurodevelopmental sequelae in some children. Neurodevelopmental abnormalities following neonatal and infant cardiac surgery include mild cognitive impairment, expressive speech and language abnormalities, impaired attention and executive function, impaired visual and spatial motor skills, as well as learning disabilities. These defects result in a significant need for early intervention, as well as rehabilitative and special education services. Central nervous system injury following repair of congenital heart defects results from a complex interaction of patient specific and environmental factors. Recent studies suggest that cerebral white matter injury characterized by periventricular leukomalacia (PVL) is common in infants with congenital heart disease particularly following cardiac surgery. Studies at our institution show that this occurs in greater than 50% of neonates following cardiac surgery, but is rare in older infants. Prolonged exposure to cardiopulmonary bypass (with or without deep hypothermic circulatory arrest) is a risk factor for PVL, possibly secondary to the systemic inflammatory response to cardiopulmonary bypass. Hypotension and hypoxemia in the early postoperative period, especially diastolic hypotension, significantly increase the risk of PVL. Future studies are needed to determine significance of PVL as a marker for long-term developmental dysfunction.

Neuropsychological outcome of infant heart transplant recipients

OBJECTIVE

To assess long-term neuropsychological outcomes of infant heart transplant recipients.

STUDY DESIGN

Fifty-five children (mean age, 6.4 years) with a primary diagnosis of hypoplastic left heart syndrome or other cardiac disorders participated in the study. Six areas of risk were assessed (birth; preoperative, intraoperative, and postoperative status; long-term medical complications; and socioeconomic factors). Neuropsychological evaluations included the following: Wechsler Scales of Intelligence, Wechsler Individual Achievement Test, Berry Visual Motor Integration Scale, Comprehensive Evaluation of Language Function, and Achenbach Child Behavioral Checklist.

RESULTS

Intellectual functioning scores revealed a mean full-scale IQ of 81 +/- 19. Intraoperative and postoperative variables (bypass time, hospital course, and lowest posttransplant pH), long-term medical complications (serious infections and posttransplant surgical procedures), and socioeconomic factors were associated with cognitive functioning. Visual-motor functioning was also related to bypass and total support time.

CONCLUSIONS

Long-term outcomes reveal low-average neuropsychological functioning and are related to intrasurgical-postsurgical, long-term medical, and socioeconomic factors. The neuropsychological and psychosocial functioning of infant heart transplant recipients will be important to address as they mature during adolescence and adulthood.

Preoperative brain injury in newborns with transposition of the great arteries

BACKGROUND

The objective was to determine the timing and mechanism of brain injury using preoperative and postoperative magnetic resonance imaging (MRI) and three-dimensional MR spectroscopic imaging (MRSI) in newborns with transposition of the great arteries (TGA) repaired with full-flow cardiopulmonary bypass.

METHODS

Ten term newborns with TGA undergoing an arterial switch operation were studied with MRI, MRSI, and neurologic examination preoperatively and postoperatively at a median of 5 days (2 to 9 days) and 19 days (14 to 26 days) of age, respectively. Five term historical controls were studied at a median of 4 days (3 to 9 days). Lactate/choline (marker of cerebral oxidative metabolism) and N-acetylaspartate (NAA)/choline (marker of cerebral metabolism and density) were measured bilaterally from the basal ganglia, thalamus, and corticospinal tracts.

RESULTS

Four TGA newborns had brain injury on the preoperative MRI. The only new lesion detected on the postoperative study was a focal white matter lesion in one newborn with a normal preoperative MRI. The MRSI of age-adjusted lactate/choline was quantitatively higher in newborns with TGA compared with those without heart disease (p < 0.0001), even in newborns without MRI evidence of preoperative brain injury. Lactate/choline decreased after surgery but remained elevated compared with controls. In newborns with TGA, those with preoperative brain injury on MRI had lower NAA/choline globally (p = 0.04) than those with normal preoperative MRI. Five newborns had a decline in NAA/choline from the preoperative to postoperative studies.

CONCLUSIONS

Abnormal brain metabolism and injury was observed preoperatively in newborns with TGA. Brain injury is not solely related to the operative course.

Regional low-flow perfusion improves neurologic outcome compared with deep hypothermic circulatory arrest in neonatal piglets

BACKGROUND

Regional low-flow perfusion is an alternative to deep hypothermic circulatory arrest, but whether regional low-flow perfusion improves neurologic outcome after deep hypothermic circulatory arrest in neonates remains unknown. We tested neurologic recovery after regional low-flow perfusion compared with deep hypothermic circulatory arrest in a neonatal piglet model.

METHODS

Sixteen neonatal piglets underwent cardiopulmonary bypass, were randomized to 90 minutes of deep hypothermic circulatory arrest or regional low-flow perfusion (10 mL.kg(-1).min(-1)) at 18 degrees C, and survived for 1 week. Standardized neurobehavioral scores were obtained on postoperative days 1, 3, and 7 (0 = no deficit to 90 = brain death). Histopathologic scores were determined on the basis of the percentage of injured and apoptotic neurons in the neocortex and hippocampus by hematoxylin and eosin and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling (0 = no injury to 4 = diffuse injury). Differences between groups were tested by using the Wilcoxon rank sum test, and results are listed as medians within a range.

RESULTS

There were no significant differences between groups during cardiopulmonary bypass. Postoperative neurobehavioral scores were abnormal in 25% (2/8) of the regional low-flow perfusion animals versus 88% (7/8) of controls. Regional low-flow perfusion animals had significantly less neurologic injury compared with controls on postoperative day 1 (0.00 [range, 0-5] vs 12.5 [range, 0-52]; P <.008). There was a trend for less severe injury in the regional low-flow perfusion group (2.0 [range, 1-4] vs 0.0 [range, 0-50]; P =.08) on hematoxylin and eosin. The degree of apoptosis was significantly less in the regional low-flow perfusion group (0.0 [range, 0-1] vs 2.5 [range, 0-4]; P =.03).

CONCLUSIONS

Regional low-flow perfusion decreases neuronal injury and improves early postoperative neurologic function after deep hypothermic circulatory arrest in neonatal piglets.

Periventricular leukomalacia is common after neonatal cardiac surgery

OBJECTIVES

Periventricular leukomalacia is necrosis of the cerebral white matter adjacent to the lateral ventricles and results from injury to immature oligodendroglia. In infants without congenital heart disease, periventricular leukomalacia is associated with an increased incidence of developmental delay and attention deficit/hyperactivity disorder. The incidence of periventricular leukomalacia and the risk factors for development of periventricular leukomalacia after infant cardiac surgery are not known.

METHODS

Magnetic resonance imaging of the brain was performed 6 to 14 days after cardiac surgery utilizing cardiopulmonary bypass with or without deep hypothermic circulatory arrest in 105 neonates and infants < or = 6 months of age.

RESULTS

Median age at surgery was 6 days (range 1-178), with 82 neonates (age < or = 30 days). Periventricular leukomalacia was found in 44 of the neonates (54%) compared with 1 of 23 infants (4%). Forward logistic regression using age at surgery as a continuous variable identified a model containing longer total support time (cardiopulmonary bypass plus deep hypothermic circulatory arrest), lower systolic blood pressure at cardiac intensive care unit admission postoperatively, lower minimum diastolic blood pressure, and Po(2) in the first 48 hours after surgery. When age at surgery was considered as a dichotomous variable (neonate versus infant), younger age at surgery replaced systolic blood pressure, Po(2), and total support time in the model. Lower minimum diastolic blood pressure was a significant risk factor in both models.

CONCLUSIONS

Periventricular leukomalacia was found in >50% of neonates after cardiac surgery but rarely in older infants. Hypoxemia and hypotension in the early postoperative period, particularly diastolic hypotension, may be important risk factors for periventricular leukomalacia.