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

Usefulness of routine head ultrasound scans before surgery for congenital heart disease

OBJECTIVE

The purpose of this study was to assess the utility of preoperative head ultrasound scan (HUS) in a cohort of newborns also undergoing preoperative MRI as part of a prospective research study of brain injury in infants having surgery for congenital heart disease (CHD).

METHODS

A total of 167 infants diagnosed with CHD were included in this 3-center study. None of the patients had clinical signs or symptoms of preoperative brain injury, and all patients received both HUS and brain MRI before undergoing surgical intervention. HUS and MRI results were reported by experienced neuroradiologists who were blinded to any specific clinical details of the study participants. The findings of the individual imaging modes were compared to evaluate for the presence of brain injury.

RESULTS

Preoperative brain injury was present on HUS in 5 infants (3%) and on MRI in 44 infants (26%) (P < .001). Four of the HUS showed intraventricular hemorrhage not seen on MRI, suggesting false-positive results, and the fifth showed periventricular leukomalacia. The predominant MRI abnormality was white matter injury (n = 32). Other findings included infarct (n = 16) and hemorrhage (n = 5).

CONCLUSIONS

Preoperative brain injury on MRI was present in 26% of infants with CHD, but only 3% had any evidence of brain injury on HUS. Among positive HUS, 80% were false-positive results. Our findings suggest that routine HUS is not indicated in asymptomatic term or near-term neonates undergoing surgery for CHD, and MRI may be a preferable tool when the assessment of these infants is warranted.

Single-ventricle anatomy predicts delayed microstructural brain development

BACKGROUND

Term newborns with congenital heart disease (CHD) show delayed brain development as early as the third trimester, especially in single-ventricle physiology (SVP). Mechanisms causing delayed brain development in CHD are uncertain but may include impaired fetal brain blood flow. Our objective was to determine if cardiac anatomy associated with obstruction to antegrade flow in the ascending aorta is predictive of delayed brain development as measured by diffusion tensor imaging and magnetic resonance spectroscopic (MRS) imaging.

METHODS

Echocardiograms from 36 term newborns with SVP were reviewed for the presence of aortic atresia and the diameter of the ascending aorta. Quantitative magnetic resonance imaging parameters measuring brain microstructural (fractional anisotropy (FA) and average diffusivity (Dav)) or metabolic development (N-acetylaspartate (NAA) and lactate/choline (Lac/Cho)) were recorded.

RESULTS

Increasing NAA/Cho and white matter (WM) FA, and decreasing Dav and Lac/Cho characterize normal brain development. Consistent with the hypothesis that delayed brain development is related to impaired brain perfusion, smaller ascending aortic diameter and aortic atresia were associated with higher Dav and lower WM FA. Echocardiogram variables were not associated with brain metabolic measures.

CONCLUSIONS

These observations support the hypothesis that obstruction to fetal cerebral blood flow impairs brain microstructural development.

Rodent brain slice model for the study of white matter injury

OBJECTIVE

Cerebral white matter (WM) injury is common after cardiac surgery in neonates and young infants who have brain immaturity and genetic abnormalities. To understand better the mechanisms associated with WM injury, we tested the adequacy of a novel ex vivo brain slice model, with a particular focus on how the maturational stage modulates the injury.

METHODS

To replicate conditions of cardiopulmonary bypass, we transferred living brain slices to a closed chamber perfused by artificial cerebrospinal fluid under controlled temperature and oxygenation. Oxygen-glucose deprivation (OGD) simulated circulatory arrest. The effects of maturation were investigated in 7- and 21-day-old mice (P7, P21) that are equivalent in maturation stage to the human fetus and young adult.

RESULTS

There were no morphologic changes in axons after 60 minutes of OGD at 15°C in both P7 WM and P21 WM. Higher temperature and longer duration of OGD were associated with significantly greater WM axonal damage, suggesting that the model replicates the injury seen after hypothermic circulatory arrest. The axonal damage at P7 was significantly less than at P21, demonstrating that immature axons are more resistant than mature axons. Conversely, a significant increase in caspase3(+) oligodendrocytes in P7 mice was identified relative to P21, indicating that oligodendrocytes in immature WM are more vulnerable than oligodendrocytes in mature WM.

CONCLUSIONS

Neuroprotective strategies for immature WM may need to focus on reducing oligodendrocyte injury. The brain slice model will be helpful in understanding the effects of cardiac surgery on the immature brain and the brain with genetic abnormalities.

New White Matter Brain Injury After Infant Heart Surgery Is Associated With Diagnostic Group and the Use of Circulatory Arrest

Background—

Abnormalities on magnetic resonance imaging scans are common both before and after surgery for congenital heart disease in early infancy. The aim of this study was to prospectively investigate the nature, timing, and consequences of brain injury on magnetic resonance imaging in a cohort of young infants undergoing surgery for congenital heart disease both with and without cardiopulmonary bypass.

Methods and Results—

A total of 153 infants undergoing surgery for congenital heart disease at <8 weeks of age underwent serial magnetic resonance imaging scans before and after surgery and at 3 months of age, as well as neurodevelopmental assessment at 2 years of age. White matter injury (WMI) was the commonest type of injury both before and after surgery. It occurred in 20% of infants before surgery and was associated with a less mature brain. New WMI after surgery was present in 44% of infants and at similar rates after surgery with or without cardiopulmonary bypass. The most important association was diagnostic group ( P <0.001). In infants having arch reconstruction, the use and duration of circulatory arrest were significantly associated with new WMI. New WMI was also associated with the duration of cardiopulmonary bypass, postoperative lactate level, brain maturity, and WMI before surgery. Brain immaturity but not brain injury was associated with impaired neurodevelopment at 2 years of age.

Conclusions—

New WMI is common after surgery for congenital heart disease and occurs at the same rate in infants undergoing surgery with and without cardiopulmonary bypass. New WMI is associated with diagnostic group and, in infants undergoing arch surgery, the use of circulatory arrest.

Development and validation of a semiquantitative brain maturation score on fetal MR images: initial results

PURPOSE

To develop a valid, reliable, and simple-to-use semiquantitative visual scale of fetal brain maturation for use in clinical fetal MR imaging assessment and interpretation.

MATERIALS AND METHODS

This is a retrospective assessment of data from a previous study that was prospective, institutional review board approved, and HIPAA compliant. Forty-eight normal pregnancies with a gestational age (GA) of 25 to 35 weeks were studied. A fetal total maturation score (fTMS) was developed by utilizing six subscores that evaluated cortical sulcation, myelination, and the germinal matrix and provided a single combined numerical value to be evaluated as a marker of brain maturity. The fTMS was correlated with GA and segmented brain volume. A regression model that associated GA based on the visual fTMS scoring was determined. The model was validated with a leave-one-out cross validation procedure.

RESULTS

Mean GA was 29.3 weeks ± 2.9 (standard deviation) (range, 25.2-35.3 weeks) and mean fTMS was 8.6 ± 3.7 (range, 4-16). The intraclass correlation coefficient between the three readers (independent and blinded) was 0.948 (P < .001). The correlations were as follows: GA and brain volume, r = 0.964 (P < .001); fTMS and brain volume, r = 0.970 (P < .001); and GA and fTMS, r = 0.975 (P < .001). A regression model to calculate GA based on fTMS yielded the following equation: calculated GA (weeks) = 22.86 + 0.748 fTMS (P < .001; adjusted R(2) = 0.946). The standard error of the model for calculation of fetal GA from the visual fTMS scale was ± 4.8 days.

CONCLUSION

If validated further, the fTMS scale might be used to assess morphologic brain maturity of fetuses between 25 and 35 weeks GA on a single-case basis in a clinical setting.

Effect of balloon atrial septostomy on cerebral oxygenation in neonates with transposition of the great arteries

BACKGROUND

The aim of this study was to determine the effect of balloon atrial septostomy (BAS) on cerebral oxygenation in neonates with transposition of the great arteries (TGA).

METHODS

In term neonates with TGA, regional cerebral tissue oxygen saturation (r(c)SO(2)) was measured using near-infrared spectroscopy (NIRS) for a period of 2 h, before BAS, after BAS, and 24 h after BAS. In neonates who did not require BAS on clinical grounds, r(c)SO(2) was measured within 24 h of admission and 24 h later.

RESULTS

BAS was performed in 12 of 21 neonates. r(c)SO(2) increased from a median of 42% (before) to 48% at 2 h after BAS (P < 0.05), as did transcutaneous arterial oxygen saturation (spO(2)) (from 72% to 85%, P < 0.01). r(c)SO(2) increased further during the next 24 h (from 48% to 64%, P < 0.05), whereas spO(2) remained stable. Although beginning from a lower baseline (42 vs. 51%, P < 0.01), r(c)SO(2) was higher in neonates treated with BAS, as compared with neonates not treated with BAS, 24 h after the procedure (64 vs. 58%, P < 0.05); spO(2) was, however, similar between the two groups.

CONCLUSION

BAS improves cerebral oxygen saturation in neonates with TGA. Complete recovery of cerebral oxygen saturation occurred only 24 h after BAS.

Neonatal cardiopulmonary bypass

Cardiac surgery with cardiopulmonary bypass is routinely used in neonates who require early repair of congenital heart diseases. However, the bypass temperature and use of deep hypothermic circulatory arrest, the composition of the priming and the acceptable degree of hemodilution, the prophylactic use of antifibrinolytic agents and steroids, the choice of myocardial protection, the best PaO2, and even the pump flow, are still subjects of debate, despite major improvements in neonatal bypass over the last decade. Nevertheless, there are some techniques that have reached a near-consensus and are highly recommended in neonates: the use of minaturized bypass circuits to reduce blood product transfusions and inflammation, ultrafiltration, and the continuous monitoring of mixed venous and regional oxygen saturations to assess adequacy of perfusion. Nevertheless, surprisingly many different techniques may lead to the same results and mortality rate. As operative mortality rates have declined, the comparison endpoints between techniques have moved and focus on morbidity rates, extubation delay, ICU and hospital length of stay; in other words, the cost and (of course) the late functional outcome are certainly the new goals of neonatal cardiopulmonary bypass.

Neurodevelopmental burden at age 5 years in patients with univentricular heart

BACKGROUND

Despite increasing survival, patients with hypoplastic left heart syndrome (HLHS) and other forms of functionally univentricular heart defects (UVHs) remain at increased risk of long-term neurodevelopmental deficits.

METHODS

A nationwide sample of 23 patients with HLHS, 13 with UVH, and 40 controls were followed prospectively until the age of 5 years, when neurologic, neuropsychological, and motor examinations and brain MRI were performed.

RESULTS

The median full-scale IQ was significantly lower in patients with HLHS (97, P < .001) and patients with UVH (112, P = .024) compared with controls (121). Major neurodevelopmental impairment was found in 26% of the patients with HLHS and 23% of those with UVH, and minor neurologic dysfunction was found in 43% and 46%, respectively. MRI revealed abnormalities, mostly ischemic changes of different degrees, in 82% of the patients with HLHS and in 56% of those with UVH. Prominent changes were significantly associated with neurodevelopmental findings and parental reports of adaptive behavior. In linear regression, significant risk factors for a worse outcome were a history of clinical seizures in connection with the primary operation, a lower diameter of the neonatal ascending aorta, and several pre-, peri-, and postoperative factors related to the primary and bidirectional Glenn operations.

CONCLUSIONS

Although median cognitive performance was within the normal range, neurodevelopmental and brain MRI abnormalities were found in the majority of the patients with UVH, and especially in those with HLHS, at preschool age. Both a narrowed ascending aorta and operation-related factors contributed to these findings.

Early postoperative changes in cerebral oxygen metabolism following neonatal cardiac surgery: effects of surgical duration

OBJECTIVE

The early postoperative period following neonatal cardiac surgery is a time of increased risk for brain injury, yet the mechanisms underlying this risk are unknown. To understand these risks more completely, we quantified changes in postoperative cerebral metabolic rate of oxygen (CMRO(2)), oxygen extraction fraction (OEF), and cerebral blood flow (CBF) compared with preoperative levels by using noninvasive optical modalities.

METHODS

Diffuse optical spectroscopy and diffuse correlation spectroscopy were used concurrently to derive cerebral blood flow and oxygen utilization postoperatively for 12 hours. Relative changes in CMRO(2), OEF, and CBF were quantified with reference to preoperative data. A mixed-effect model was used to investigate the influence of total support time and deep hypothermic circulatory arrest duration on relative changes in CMRO(2), OEF, and CBF.

RESULTS

Relative changes in CMRO(2), OEF, and CBF were assessed in 36 patients, 21 with single-ventricle defects and 15 with 2-ventricle defects. Among patients with single-ventricle lesions, deep hypothermic circulatory arrest duration did not affect relative changes in CMRO(2), CBF, or OEF (P > .05). Among 2-ventricle patients, total support time was not a significant predictor of relative changes in CMRO(2) or CBF (P > .05), although longer total support time was associated significantly with greater increases in relative change of postoperative OEF (P = .008).

CONCLUSIONS

Noninvasive diffuse optical techniques were used to quantify postoperative relative changes in CMRO(2), CBF, and OEF for the first time in this observational pilot study. Pilot data suggest that surgical duration does not account for observed variability in the relative change in CMRO(2), and that more comprehensive clinical studies using the new technology are feasible and warranted to elucidate these issues further.

Erythropoietin neuroprotection in neonatal cardiac surgery: a phase I/II safety and efficacy trial

OBJECTIVES

Neonates undergoing complex congenital heart surgery have a significant incidence of neurologic problems. Erythropoietin has antiapoptotic, antiexcitatory, and anti-inflammatory properties to prevent neuronal cell death in animal models, and improves neurodevelopmental outcomes in full-term neonates with hypoxic ischemic encephalopathy. We designed a prospective phase I/II trial of erythropoietin neuroprotection in neonatal cardiac surgery to assess safety and indicate efficacy.

METHODS

Neonates undergoing surgery for D-transposition of the great vessels, hypoplastic left heart syndrome, or aortic arch reconstruction were randomized to 3 perioperative doses of erythropoietin or placebo. Neurodevelopmental testing using the Bayley Scales of Infant and Toddler Development III was performed at age 12 months.

RESULTS

Fifty-nine patients received the study drug. Safety profile, including magnetic resonance imaging brain injury, clinical events, and death, was not different between groups. Three patients in each group died. Forty-two patients (22 in the erythropoietin group and 20 in the placebo group; 79% of survivors) returned for 12-month follow-up. In the group receiving erythropoietin, mean Cognitive Scale scores were 101.1 ± 13.6, Language Scale scores were 88.5 ± 12.8, and Motor Scale scores were 89.9 ± 12.3. In the group receiving placebo, Cognitive Scale scores were 106.3 ± 10.8 (P = .19), Language Scores were 92.4 ± 12.4 (P = .33), and Motor Scale scores were 92.6 ± 14.1 (P = .51).

CONCLUSIONS

Safety profile for erythropoietin administration was not different than placebo. Neurodevelopmental outcomes were not different between groups; however, this pilot study was not powered to definitively address this outcome. Lessons learned suggest optimized study design features for a larger prospective trial to definitively address the utility of erythropoietin for neuroprotection in this population.

Physician counseling, informed consent and parental decision making for infants with hypoplastic left-heart syndrome

Until the development in 1980 by William Norwood of a staged palliative surgical procedure for hypoplastic left heart syndrome (HPLHS), there was no treatment for that condition. With medical developments in the 1980s, parents had the option of the Norwood procedure, transplantation or comfort care for a child born with HPLHS. With an improvement in the survival rate for the Norwood procedure from an initial 30% to now better than 80%, some physicians believe that comfort care should no longer be an option. If, however, medically sophisticated parents, who know the neurological and motor skills impairments that accompany HPLHS, object to the surgery, they are allowed to opt for comfort care. This two-pronged approach to medical treatment seems to violate the norms on equity and fairness in the care of the patient. Parents need to be informed about long-term neurological and motor skill development as well as survival rates to give informed consent.

Results of genome-wide analyses on neurodevelopmental phenotypes at four-year follow-up following cardiac surgery in infancy

BACKGROUND

Adverse neurodevelopmental sequelae are reported among children who undergo early cardiac surgery to repair congenital heart defects (CHD). APOE genotype has previously been determined to contribute to the prediction of these outcomes. Understanding further genetic causes for the development of poor neurobehavioral outcomes should enhance patient risk stratification and improve both prevention and treatment strategies.

METHODS

We performed a prospective observational study of children who underwent cardiac surgery before six months of age; this included a neurodevelopmental evaluation between their fourth and fifth birthdays. Attention and behavioral skills were assessed through parental report utilizing the Attention Deficit-Hyperactivity Disorder-IV scale preschool edition (ADHD-IV), and Child Behavior Checklist (CBCL/1.5-5), respectively. Of the seven investigated, three neurodevelopmental phenotypes met genomic quality control criteria. Linear regression was performed to determine the effect of genome-wide genetic variation on these three neurodevelopmental measures in 316 subjects.

RESULTS

This genome-wide association study identified single nucleotide polymorphisms (SNPs) associated with three neurobehavioral phenotypes in the postoperative children ADHD-IV Impulsivity/Hyperactivity, CBCL/1.5-5 PDPs, and CBCL/1.5-5 Total Problems. The most predictive SNPs for each phenotype were: a LGALS8 intronic SNP, rs4659682, associated with ADHD-IV Impulsivity (P=1.03 × 10(-6)); a PCSK5 intronic SNP, rs2261722, associated with CBCL/1.5-5 PDPs (P=1.11 × 10(-6)); and an intergenic SNP, rs11617488, 50 kb from FGF9, associated with CBCL/1.5-5 Total Problems (P=3.47 × 10(-7)). 10 SNPs (3 for ADHD-IV Impulsivity, 5 for CBCL/1.5-5 PDPs, and 2 for CBCL/1.5-5 Total Problems) had p<10(-5).

CONCLUSIONS

No SNPs met genome-wide significance for our three neurobehavioral phenotypes; however, 10 SNPs reached a threshold for suggestive significance (p<10(-5)). Given the unique nature of this cohort, larger studies and/or replication are not possible. Studies to further investigate the mechanisms through which these newly identified genes may influence neurodevelopment dysfunction are warranted.

Neurodevelopmental outcomes in children with congenital heart disease: evaluation and management: a scientific statement from the American Heart Association

BACKGROUND

The goal of this statement was to review the available literature on surveillance, screening, evaluation, and management strategies and put forward a scientific statement that would comprehensively review the literature and create recommendations to optimize neurodevelopmental outcome in the pediatric congenital heart disease (CHD) population.

METHODS AND RESULTS

A writing group appointed by the American Heart Association and American Academy of Pediatrics reviewed the available literature addressing developmental disorder and disability and developmental delay in the CHD population, with specific attention given to surveillance, screening, evaluation, and management strategies. MEDLINE and Google Scholar database searches from 1966 to 2011 were performed for English-language articles cross-referencing CHD with pertinent search terms. The reference lists of identified articles were also searched. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. A management algorithm was devised that stratified children with CHD on the basis of established risk factors. For those deemed to be at high risk for developmental disorder or disabilities or for developmental delay, formal, periodic developmental and medical evaluations are recommended. A CHD algorithm for surveillance, screening, evaluation, reevaluation, and management of developmental disorder or disability has been constructed to serve as a supplement to the 2006 American Academy of Pediatrics statement on developmental surveillance and screening. The proposed algorithm is designed to be carried out within the context of the medical home. This scientific statement is meant for medical providers within the medical home who care for patients with CHD.

CONCLUSIONS

Children with CHD are at increased risk of developmental disorder or disabilities or developmental delay. Periodic developmental surveillance, screening, evaluation, and reevaluation throughout childhood may enhance identification of significant deficits, allowing for appropriate therapies and education to enhance later academic, behavioral, psychosocial, and adaptive functioning.

Neurodevelopmental outcomes after congenital heart surgery and strategies for improvement

PURPOSE OF REVIEW

The present review focuses on neurodevelopmental and neuropsychologic outcomes following neonatal and infant heart surgery for complex congenital heart lesions. The data include recent reports on perioperative MRI and recent results of randomized clinical trials addressing perioperative variables.

RECENT FINDINGS

Advancements in magnetic resonance techniques have reinforced earlier data that newborns with complex congenital heart lesions are frequently born with brain immaturity. Randomized clinical trials have looked at several important perioperative candidate predictors as potential independent risk factors for worsened neurodevelopmental outcomes: no difference was found between regional cerebral perfusion and deep hypothermic circulatory arrest on 1-year outcomes; no difference was found between the modified Blalock-Taussig shunt and the right ventricular to pulmonary artery shunt as part of the Norwood procedure on 14-month outcomes; at 16-year testing for individuals with transposition of the great arteries following the arterial switch operation, no significant difference was found between low-flow cardiopulmonary bypass and deep hypothermic circulatory arrest.

SUMMARY

Randomized clinical, cross-sectional, and prospective trials have explored robust analyses looking for independent risk factors for worsened neurodevelopmental outcomes. Most of these risk factors are patient-related or socioeconomic, with only a few potentially modifiable.

Neurodevelopmental outcomes after regional cerebral perfusion with neuromonitoring for neonatal aortic arch reconstruction

BACKGROUND

In this study we report magnetic resonance imaging (MRI) brain injury and 12-month neurodevelopmental outcomes when regional cerebral perfusion (RCP) is used for neonatal aortic arch reconstruction.

METHODS

Fifty-seven neonates receiving RCP during aortic arch reconstruction were enrolled in a prospective outcome study. RCP flows were determined by near-infrared spectroscopy and transcranial Doppler monitoring. Brain MRI was performed preoperatively and 7 days postoperatively. Bayley Scales of Infant Development III was performed at 12 months.

RESULTS

Mean RCP time was 71 ± 28 minutes (range, 5 to 121 minutes) and mean flow was 56.6 ± 10.6 mL/kg/min. New postoperative MRI brain injury was seen in 40% of patients. For 35 RCP patients at age 12 months, mean Bayley Scales III Composite standard scores were: Cognitive, 100.1 ± 14.6 (range, 75 to 125); Language, 87.2 ± 15.0 (range, 62 to 132); and Motor, 87.9 ± 16.8 (range, 58 to 121). Increasing duration of RCP was not associated with adverse neurodevelopmental outcomes.

CONCLUSIONS

Neonatal aortic arch repair with RCP using a neuromonitoring strategy results in 12-month cognitive outcomes that are at reference population norms. Language and motor outcomes are lower than the reference population norms by 0.8 to 0.9 standard deviations. The neurodevelopmental outcomes in this RCP cohort demonstrate that this technique is effective and safe in supporting the brain during neonatal aortic arch reconstruction.

Changing expectations for neurological outcomes after the neonatal arterial switch operation

BACKGROUND

Expectations for outcomes after the neonatal arterial switch operation (ASO) continue to change. This cohort study describes neurodevelopmental outcomes at age 12 months after neonatal ASO, and analyzes both modifiable and nonmodifiable factors for association with adverse outcomes.

METHODS

Patients who underwent an ASO (n=30) were enrolled in a prospective outcome study, with comprehensive clinical data collection during the first 12 months of life. Brain magnetic resonance imaging was done preoperatively and 7 days postoperatively, and the Bayley Scales of Infant Development III was performed at age 12 months.

RESULTS

Ten of 30 patients (33%) had preoperative magnetic resonance imaging injury; 13 of 30 patients (43%) had new postoperative magnetic resonance imaging injury. Twenty patients (67%) had Bayley Scales of Infant Development III: Cognitive Composite standard score mean was 104.8±15.0, Language Composite standard score median was 90.0 (25th to 75th percentile, 83 to 94), and Motor Composite standard score mean was 92.3±14.2. Best subsets multivariable analysis found associations between lower preoperative and intraoperative cerebral oxygen saturation, preoperative magnetic resonance imaging brain injury, total bypass time, and total midazolam dose and lower Bayley Scales of Infant Development III scores at age 12 months.

CONCLUSIONS

At 12 months after ASO, neurodevelopmental outcome means were within normal population ranges. The new associations reported in this study between potentially modifiable perioperative factors and outcomes require investigations in larger patient cohorts. Beyond survival, which was 100% in this cohort, factors influencing quality of life including neurodevelopmental outcomes should be routinely investigated in studies of ASO patients.

Younger gestational age is associated with worse neurodevelopmental outcomes after cardiac surgery in infancy

OBJECTIVE

Evaluate the impact of near-term delivery on neurodevelopmental (ND) outcomes in children with congenital heart disease (CHD).

METHODS

Secondary analysis of data from a study of genetic polymorphisms and ND outcomes after cardiac surgery in infants. The effect of gestational age (GA) as a continuous variable on ND outcomes was evaluated using general linear regression models. GA was also evaluated as a categorical variable to seek a threshold for better outcomes. ND domains tested at 4 years of age included cognition, language skills, attention, impulsivity, memory, executive function, social competence, visual-motor, and fine-motor skills.

RESULTS

ND outcomes and GA were available for 378 infants. Median GA was 39 weeks (range, 28-42 weeks) with 351 born at 36 weeks or more (near-term/term). In univariate analysis of the near-term/term subgroup, older GA predicted better performance for cognition, visual-motor, and fine-motor skills. After covariate adjustment, older GA predicted better performance for fine-motor skills (P = .018). Performance for cognition, language, executive function, social skills, visual-motor, and fine-motor skills was better for those born at 39 to 40 weeks of GA or more versus those born at less than 39 weeks (all P < .05).

CONCLUSIONS

These findings are consistent with the hypothesis that delivery before 39 to 40 weeks of GA is associated with worse outcomes in patients with CHD. Early delivery of a child with CHD is often indicated because of maternal or fetal health issues. In the absence of these concerns, these data suggest that elective (or spontaneous) delivery at 39 to 40 weeks of GA is associated with better ND outcomes.

Early developmental outcome in children with hypoplastic left heart syndrome and related anomalies: the single ventricle reconstruction trial

BACKGROUND

Survivors of the Norwood procedure may experience neurodevelopmental impairment. Clinical trials to improve outcomes have focused primarily on methods of vital organ support during cardiopulmonary bypass.

METHODS AND RESULTS

In the Single Ventricle Reconstruction trial of the Norwood procedure with modified Blalock-Taussig shunt versus right-ventricle-to-pulmonary-artery shunt, 14-month neurodevelopmental outcome was assessed by use of the Psychomotor Development Index (PDI) and Mental Development Index (MDI) of the Bayley Scales of Infant Development-II. We used multivariable regression to identify risk factors for adverse outcome. Among 373 transplant-free survivors, 321 (86%) returned at age 14.3 ± 1.1 (mean ± SD) months. Mean PDI (74 ± 19) and MDI (89 ± 18) scores were lower than normative means (each P<0.001). Neither PDI nor MDI score was associated with type of Norwood shunt. Independent predictors of lower PDI score (R(2)=26%) were clinical center (P=0.003), birth weight <2.5 kg (P=0.023), longer Norwood hospitalization (P<0.001), and more complications between Norwood procedure discharge and age 12 months (P<0.001). Independent risk factors for lower MDI score (R(2)=34%) included center (P<0.001), birth weight <2.5 kg (P=0.04), genetic syndrome/anomalies (P=0.04), lower maternal education (P=0.04), longer mechanical ventilation after the Norwood procedure (P<0.001), and more complications after Norwood discharge to age 12 months (P<0.001). We found no significant relationship of PDI or MDI score to perfusion type, other aspects of vital organ support (eg, hematocrit, pH strategy), or cardiac anatomy.

CONCLUSIONS

Neurodevelopmental impairment in Norwood survivors is more highly associated with innate patient factors and overall morbidity in the first year than with intraoperative management strategies. Improved outcomes are likely to require interventions that occur outside the operating room.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Validation of diffuse correlation spectroscopic measurement of cerebral blood flow using phase-encoded velocity mapping magnetic resonance imaging

Diffuse correlation spectroscopy (DCS) is a novel optical technique that appears to be an excellent tool for assessing cerebral blood flow in a continuous and non-invasive manner at the bedside. We present new clinical validation of the DCS methodology by demonstrating strong agreement between DCS indices of relative cerebral blood flow and indices based on phase-encoded velocity mapping magnetic resonance imaging (VENC MRI) of relative blood flow in the jugular veins and superior vena cava. Data were acquired from 46 children with single ventricle cardiac lesions during a hypercapnia intervention. Significant increases in cerebral blood flow, measured both by DCS and by VENC MRI, as well as significant increases in oxyhemoglobin concentration, and total hemoglobin concentration, were observed during hypercapnia. Comparison of blood flow changes measured by VENC MRI in the jugular veins and by DCS revealed a strong linear relationship, R=0.88, p<0.001, slope=0.91±0.07. Similar correlations were observed between DCS and VENC MRI in the superior vena cava, R=0.77, slope=0.99±0.12, p<0.001. The relationship between VENC MRI in the aorta and DCS, a negative control, was weakly correlated, R=0.46, slope=1.77±0.45, p<0.001.

Neurological injury and anesthetic neurotoxicity following neonatal cardiac surgery: does the head rule the heart or the heart rule the head?

The improvements in care of children with heart disease have resulted in a major decrease in mortality and increased attention to adverse events and quality of survival. There is important neurological morbidity in children with congenital heart disease. Some problems such as stroke or seizure may be immediately apparent, but others, such as learning disability and motor delay emerge over time. The etiology is multifactorial and includes genetic, procedural and social causes. Only some factors are modifiable. Over the last decade, evidence has been presented that anesthetic drugs may be a potential cause of CNS morbidity. Neonates and infants may be particularly vulnerable to this. The purpose of this article is to describe the multiple known causes of neurodevelopmental impairment in children with heart disease, including anesthetic agents, and to explore the relationship between congenital heart disease and its treatment in this regard.

White matter protection in congenital heart surgery

BACKGROUND

Neurodevelopmental delays in motor skills and white matter (WM) injury have been documented in congenital heart disease and after pediatric cardiac surgery. The lack of a suitable animal model has hampered our understanding of the cellular mechanisms underlying WM injury in these patients. Our aim is to identify an optimal surgical strategy for WM protection to reduce neurological injury in congenital heart disease patients.

METHODS AND RESULTS

We developed a porcine cardiopulmonary bypass model that displays area-dependent WM maturation. In this model, WM injury was identified after cardiopulmonary bypass-induced ischemia-reperfusion injury. The degree of injury was inversely correlated with the maturation stage, which indicates maturation-dependent vulnerability of WM. Within different oligodendrocyte developmental stages, we show selective vulnerability of O4+ preoligodendrocytes, whereas oligodendrocyte progenitor cells were resistant to insults. This indicates that immature WM is vulnerable to cardiopulmonary bypass-induced injury but has an intrinsic potential for recovery mediated by endogenous oligodendrocyte progenitor cells. Oligodendrocyte progenitor cell number decreased with age, which suggests that earlier repair allows successful WM development. Oligodendrocyte progenitor cell proliferation was observed within a few days after cardiopulmonary bypass-induced ischemia-reperfusion injury; however, by 4 weeks, arrested oligodendrocyte maturation and delayed myelination were detected. Logistic model confirmed that maintenance of higher oxygenation and reduction of inflammation were effective in minimizing the risk of injury at immature stages of WM development.

CONCLUSIONS

Primary repair in neonates and young infants potentially provides successful WM development in congenital heart disease patients. Cardiac surgery during this susceptible period should avoid ischemia-reperfusion injury and minimize inflammation to prevent long-term WM-related neurological impairment.

Multimodality Neuromonitoring for Pediatric Cardiac Surgery

Brain injury remains a source of morbidity associated with congenital heart surgery. Intraoperative neuromonitoring is used by many centers to help minimize neurologic injury and improve outcomes. Neuromonitoring at our institution is performed using a combination of near-infrared spectroscopy, transcranial Doppler ultrasound, electroencephalography, and somatosensory evoked potentials. Adverse or concerning parameters instigate attempts at corrective intervention. A review of the literature regarding neuromonitoring studies in pediatric cardiac surgery shows that evidence is limited to demonstrate that intraoperative neuromonitoring is associated with improved neurologic outcomes. Further clinical research is needed to assess the utility and cost-effectiveness of intraoperative neuromonitoring for pediatric heart surgery.

Regional alterations in cerebral growth exist preoperatively in infants with congenital heart disease

OBJECTIVES

Magnetic resonance imaging has been used to define the neurologic abnormalities in infants with congenital heart disease (CHD), including preoperative injury and delayed brain maturation. The present study used qualitative scoring, cerebral biometry, and diffusion imaging to characterize the preoperative brain abnormalities in infants with CHD, including the identification of regions of greater vulnerability.

METHODS

A total of 67 infants with CHD had preoperative magnetic resonance imaging scans available for analysis of brain injury using qualitative scoring and brain development using qualitative scoring, metrics, and diffusion imaging.

RESULTS

Qualitative abnormalities were common, with 42% of infants having preoperative focal white matter lesions. Infants with CHD had smaller brain measures in the frontal lobe, parietal lobe, cerebellum, and brainstem (P < .001), with the frontal lobe and brainstem displaying the greatest alterations (P < .001). A smaller brain size in the frontal and parietal lobes correlated with delayed white matter microstructure reflected by diffusion imaging.

CONCLUSIONS

Infants with CHD commonly display brain injury and delayed brain development. Regional alterations in brain size are present, with the frontal lobe and brainstem demonstrating the greatest alterations. This might reflect a combination of developmental vulnerability and regional differences in cerebral circulation.

Neurodevelopment and quality of life for children with hypoplastic left heart syndrome: current knowns and unknowns

The aim of this review is to describe the current state of knowledge related to neurodevelopmental outcomes and quality of life for children with hypoplastic left heart syndrome and to explore future questions to be answered for this group of children.

Outcomes and risk factors for mortality in premature neonates with critical congenital heart disease

We sought to describe contemporary outcomes and identify risk factors for hospital mortality in premature neonates with critical congenital heart disease who were referred for early intervention. Neonates who were born before 37 weeks' gestation with critical congenital heart disease and admitted to our institution from 2002 to 2008 were included in this retrospective cohort study. Critical congenital heart disease was defined as a defect requiring surgical or transcatheter cardiac intervention or a defect resulting in death within the first 28 days of life. Logistic regression analyses were performed to identify risk factors for mortality before hospital discharge. The study included 180 premature neonates, of whom 37 (21%) died during their initial hospitalization, including 6 (4%) before cardiac intervention and 31 (17%) after cardiac intervention. For the 174 patients undergoing cardiac intervention, independent risk factors for mortality were a 5 min Apgar score ≤ 7, need for preintervention mechanical ventilation, and Risk Adjustment in Congenital Heart Surgery category ≥ 4 or not assignable. Mortality for premature infants with critical congenital heart disease who are referred for early intervention remains high. Patients with lower Apgar scores who receive preintervention mechanical ventilation and undergo more complex procedures are at greatest risk.

Amplitude-integrated electroencephalography and brain injury in infants undergoing Norwood-type operations

BACKGROUND

Perioperative brain injury is common in infants undergoing cardiac surgery. Amplitude-integrated electroencephalography (aEEG) provides real-time neurologic monitoring and can identify seizures and abnormalities of background cerebral activity. We aimed to determine the incidence of perioperative electrical seizures, and to establish the background pattern of aEEG, in neonates undergoing Norwood-type palliations for complex congenital heart disease in relation to outcome at 2 years.

METHODS

Thirty-nine full-term neonates undergoing Norwood-type operations underwent aEEG monitoring before and during surgery and for 72 hours postoperatively. The perfusion strategy included full-flow moderately hypothermic cardiopulmonary bypass with antegrade cerebral perfusion. Amplitude-integrated electroencephalography tracings were reviewed for seizure activity and background pattern. Survivors underwent neurodevelopmental outcome assessment using the Bayley Scales of Infant Development (3rd edition) at 2 years of age.

RESULTS

Thirteen (33%) infants had electrical seizures, including 9 with intraoperative seizures and 7 with postoperative seizures. Seizures were associated with significantly increased mortality, but not with neurodevelopmental impairment in survivors. Delay in recovery of the aEEG background beyond 48 hours was also associated with increased mortality and worse motor development.

CONCLUSIONS

Perioperative seizures were common in this cohort. Intraoperative seizures predominantly affected the left hemisphere during antegrade cerebral perfusion. Delayed recovery in aEEG background was associated with increased risk of early mortality and worse motor development. Ongoing monitoring is essential to determine the longer-term significance of these findings.

Congenital heart surgery in infants: effects of acute kidney injury on outcomes

OBJECTIVES

We sought to characterize factors and outcomes associated with postoperative acute kidney injury in infants undergoing cardiac surgery.

METHODS

We retrospectively studied 430 infants (<90 days) who underwent heart surgery for congenital defects. With a pediatric modified version of the Acute Kidney Injury Network classification, we performed statistical analyses to detect factors and outcomes associated with postoperative acute kidney injury.

RESULTS

Postoperative acute kidney injury occurred in 225 patients (52%): 135 patients (31%) reached maximum acute kidney injury stage I, 59 (14%) reached stage II, and 31 (7%) reached stage III. On multivariable analysis, single-ventricle status (odds ratio, 1.6; 95% confidence interval, 1.08-2.37; P = .02), cardiopulmonary bypass (odds ratio, 1.2; 95% confidence interval 1.01-1.47; P = .04), and higher reference serum creatinine (odds ratio, 5.1; 95% confidence interval, 1.94-13.2; P = .0009) were associated with postoperative acute kidney injury. Thirty-two (7%) patients died in the hospital. Multivariable logistic regression showed that more severe acute kidney injury was associated with in-hospital mortality (maximum acute kidney injury stage II odds ratio, 5.1; 95% confidence interval, 1.7-15.2; P = .004; maximum acute kidney injury stage III odds ratio, 9.46; 95% confidence interval, 2.91-30.7; P = .0002) and longer mechanical ventilation and inotropic support. All acute kidney injury stages were associated with longer intensive care durations. Stage III acute kidney injury was associated with systemic ventricular dysfunction at hospital discharge.

CONCLUSIONS

Perioperative acute kidney injury is common in infant heart surgery and portends a poor clinical outcome.

Should what we know about neurobehavioral development, complex congenital heart disease, and brain maturation affect the timing of corrective cardiac surgery?

Despite remarkable improvements in perioperative care, adverse neurobehavioral outcomes following neonatal and infant cardiac surgery are commonplace and are associated with substantial morbidity. It is becoming increasingly clear that complex congenital heart disease is associated with both abnormalities in neuroanatomic development and a delay in fetal brain maturation. Substantial cerebral ischemic/hypoxic injury has been detected in neonates with complex congenital heart disease both prior to and following corrective cardiac surgery. The brain of the neonate with complex congenital heart disease appears to be uniquely vulnerable to the types of ischemic/hypoxic injury associated with perioperative care. It remains to be determined whether delaying surgical correction to allow for brain maturation will be associated with improvements in neurobehavioral outcomes.

Near-infrared spectroscopy as a hemodynamic monitor in critical illness

BACKGROUND

Near-infrared spectroscopy has moved from a research tool to a widely used clinical monitor in the critically ill pediatric patient over the last decade. The physiological and clinical evidence supporting this technology in practice is reviewed here.

METHODOLOGY

A search of MEDLINE and PubMed was conducted to find validation studies, controlled trials, and other reports of near-infrared spectroscopy use in children and adults in the clinical setting. Guidelines published by the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS

The biophysical properties of near-infrared spectroscopy devices allow measurement of capillary-venous oxyhemoglobin saturation in tissues a few centimeters beneath the surface sensor with validated accuracy in neonates, infants, and small patients. The biologic basis for the relationship of capillary-venous oxyhemoglobin saturation to cerebral injury has been described in animal and human studies. Normal ranges for cerebral and somatic capillary-venous oxyhemoglobin saturation have been described for normal newborns and infants and children with congenital heart disease and other disease states. The capillary-venous oxyhemoglobin saturation from both cerebral and somatic regions has been used to estimate mixed venous saturation and to predict biochemical shock, multiorgan dysfunction, and mortality in different populations. The relationship of cerebral capillary-venous oxyhemoglobin saturation to neuroimaging and functional assessment of outcome is limited but ongoing. Although there are numerous conflicting reports in small populations, expert opinion would suggest that special use may exist for near-infrared spectroscopy in patients with complex circulatory anatomy, with extremes of physiology, and in whom extended noninvasive monitoring is useful.

CONCLUSIONS

Class II, level B evidence supports the conclusion that near-infrared spectroscopy offers a favorable risk-benefit profile and can be effective and beneficial as a hemodynamic monitor for the care of critically patients.

Abnormal brain structure and function in newborns with complex congenital heart defects before open heart surgery: a review of the evidence

Newborns with complex congenital heart defects are at high risk for developing neurological abnormalities. It is important to understand the timing, progression, and extent of these abnormalities to better elucidate their potential impact on neurodevelopment, and their implications for early screening and intervention. This review synthesizes the recent literature describing neurological and neurobehavioral abnormalities observed in fetuses and newborns before cardiac surgery. A considerable proportion of newborns with complex congenital heart defects exhibit neurobehavioral and electrophysiological abnormalities preoperatively. Likewise, conventional neuroimaging studies reported that a high percentage of this population experienced brain injury. Advanced neuroimaging modalities indicated that fetuses showed delayed third trimester brain growth, and newborns showed impaired white matter maturation, reduced N-acetylaspartate, and increased lactate. These findings suggest a fetal or early postnatal onset of impaired brain growth and development. Consequently, reliable methods for early screening and subsequent developmental intervention must be implemented.

Cerebral oximetry for pediatric anesthesia: why do intelligent clinicians disagree?

Reflectance near-infrared spectroscopy has been used to measure cortical tissue oximetry for more than 30 years. In that time, many centers have adopted the routine use of the cerebral oximeter for children having repair of congenital heart lesions, while some prominent academic centers have resisted routine use of these monitors citing lack of definitive evidence for outcome benefit. In this review, we provide an overview of the method used to measure cerebral oximetry, as well as validation and clinical outcome data that have accrued from the use of cerebral oximeters. We discuss the peculiarities of evidentiary review for monitoring devices, and the confounding errors that occur when a monitor is evaluated as a therapeutic intervention. We outline the physiologic basis of cerebral desaturation and the shifts in practice that have occurred with implementation of NIRS monitoring.

Major themes for 2010 in cardiothoracic and vascular anesthesia

Significant variability in transfusion practice persists despite guidelines. Although the lysine analogues are effective antifibrinolytics, safety concerns exist with high doses tranexamic acid. Despite recombinant activated factor VII promising results in massive bleeding after cardiac surgery, it significantly increases arterial thromboembolic risk. Aortic valve repair may evolve to standard of care. Transcatheter aortic valve implantation is an established therapy for aortic stenosis. The cardiovascular anesthesiologist features prominently in the new guidelines for thoracic aortic disease. Although intense angiotensin blockade improves outcomes in heart failure, it might aggravate the maintenance of perioperative systemic vascular tone. Ultrafiltration is an alternative to diuresis for volume overload in heart failure. Management of heart failure titrated to brain natriuretic peptide activity reduces mortality. A major surgical advance has been the significant outcome improvement achieved with continuous-flow left ventricular assist devices. Advanced liver disease is a significant predictor for perioperative bleeding, transfusion and mortality after ventricular assist device insertion. Acquired von Willebrand syndrome is not only common in patients with these devices but often aggravating bleeding and transfusion in this setting. Metabolic myocardial modulation with perhexilene significantly enhances effort tolerance in hypertrophic cardiomyopathy. A landmark report has highlighted future priorities in this disease. Pediatric cardiac surgical trials have revealed the importance of perioperative cerebral oxygen saturation monitoring and the Sano shunt. Advances in pediatric-specific ventricular assist devices will likely revolutionize pediatric heart failure. Recent reports have highlighted the priorities for future perioperative trials and for training models in pediatric cardiac anesthesia.

Effects of congenital heart disease on brain development

Brain and heart development occurs simultaneously in the fetus with congenital heart disease. Early morphogenetic programs in each organ share common genetic pathways. Brain development occurs across a more protracted time-course with striking brain growth and activity-dependent formation and refinement of connections in the third trimester. This development is associated with increased metabolic activity and the brain is dependent upon the heart for oxygen and nutrient delivery. Congenital heart disease leads to derangements of fetal blood flow that result in impaired brain growth and development that can be measured with advanced magnetic resonance imaging. Delayed development results in a unique vulnerability to cerebral white matter injury in newborns with congenital heart disease. Delayed brain development and acquired white matter injury may underlay mild but pervasive neurodevelopmental impairment commonly observed in children following neonatal congenital heart surgery.

Relationship of intraoperative cerebral oxygen saturation to neurodevelopmental outcome and brain magnetic resonance imaging at 1 year of age in infants undergoing biventricular repair

BACKGROUND

Near-infrared spectroscopy monitoring of cerebral oxygen saturation (rSo(2)) has become routine in many centers, but no studies have reported the relationship of intraoperative near-infrared spectroscopy to long-term neurodevelopmental outcomes after cardiac surgery.

METHODS AND RESULTS

Of 104 infants undergoing biventricular repair without aortic arch reconstruction, 89 (86%) returned for neurodevelopmental testing at 1 year of age. The primary near-infrared spectroscopy variable was the integrated rSo(2) (area under the curve) for rSo(2) <or=45%; secondary variables were the average and minimum rSo(2) by perfusion phase and at specific time points. Psychomotor and mental development indexes of the Bayley scales, head circumference, neurological examination, and abnormalities on brain magnetic resonance imaging did not differ between subjects according to a threshold level for rSo(2) of 45%. Lower Psychomotor Development Index scores were modestly associated with lower average (r=0.23, P=0.03) and minimum (r=0.22, P=0.04) rSo(2) during the 60-minute period after cardiopulmonary bypass but not with other perfusion phases. Hemosiderin foci on brain magnetic resonance imaging were associated with lower average rSo(2) from postinduction to 60 minutes post cardiopulmonary bypass (71+/-10% versus 78+/-6%, P=0.01) and with lower average rSO(2) during the rewarming phase (72+/-12% versus 83+/-9%, P=.003) and during the 60-minute period following cardiopulmonary bypass (65+/-11% versus 75+/-10%, P=0.009). In regression analyses that adjusted for age <or=30 days, Psychomotor Development Index score (P=0.02) and brain hemosiderin (P=0.04) remained significantly associated with rSo(2) during the 60-minute period following cardiopulmonary bypass.

CONCLUSIONS

Perioperative periods of diminished cerebral oxygen delivery, as indicated by rSo(2), are associated with 1-year Psychomotor Development Index and brain magnetic resonance imaging abnormalities among infants undergoing reparative heart surgery. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00006183.