Multimodality evoked potential findings in infants with congenital heart defects

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

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

Dextro-Transposition of Great Arteries and Neurodevelopmental Outcomes: A Review of the Literature

Background: Arterial switch operation (ASO) is the gold-standard surgical approach for dextro-transposition of the great arteries (D-TGA). It is performed during the neonatal period and has almost diminished the previously high mortality rate (from 90% if left untreated to <0.5%). Despite the impressively high survival rates, the surgical procedure itself—along with the chronic post-operative complications and the perinatal impaired cerebral oxygen delivery—introduces multiple and cumulative risk factors for neurodevelopmental impairment. Method: This study is a review of English articles, using PUBMED and applying the following search terms, “transposition of the great arteries”, “neurodevelopment”, “autism”, “cerebral palsy”, and “attention-deficit hyperactivity disorder”. Data were extracted by two authors. Results: Even though general IQ is mainly found within the normal range, D-TGA children and adolescents display reduced performance in the assignments of executive functions, fine motor functions, attention, working memory, visual−spatial skills, and higher-order language skills. Moreover, D-TGA survivors may eventually struggle with inferior academic achievements and psychiatric disorders such as depression, anxiety, and ADHD. Conclusions: The existing literature concerning the neurodevelopment of D-TGA patients suggests impairment occurring during their lifespan. These findings underline the importance of close developmental surveillance so that D-TGA patients can better reach their full potential.

Neonatal brain protection in cardiac surgery and the role of intraoperative neuromonitoring

Improving mortality rates in children undergoing surgery for congenital heart disease has enabled a shift in focus to improving morbidity, particularly with respect to neurological complications. Various factors have been implicated in influencing neurological outcomes. We share our experience in formulating a customized cardiopulmonary bypass (CPB) protocol based on currently available evidence. Theoretical advantages of intraoperative neuromonitoring during CPB, specifically use of near-infrared spectroscopy, will be discussed in the context of methodologies to monitor cerebral perfusion during surgery.

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.

Neonatal somatosensory evoked potentials: maturational aspects and prognostic value

The aim of this prospective study was to evaluate the diagnostic role of somatosensory evoked potentials (SEP) during the neonatal period with regard to maturational changes and prognostic value in perinatal hypoxic-ischemic encephalopathy. Median nerve SEP analysis was performed in 31 healthy infants (group A1, 33-35 weeks, n = 10; group A2, 36-37 weeks, n = 11; group A3, 38-41 weeks, n = 10) and in 10 term infants with hypoxic-ischemic encephalopathy (group B). Cortical latency N1 and central conduction time values were analyzed for group A in relation to postconceptional age and postnatal age and for group B in relation to degree of hypoxic-ischemic encephalopathy and neurodevelopmental outcome (at the mean age of 6.6 + or - 1.6 years). Central latencies were correlated with postconceptional age but not postnatal age. Mean N1 latency and central conduction time values did not differ significantly between groups A1 and A2; the most pronounced decrease was between groups A2 and A3 (postconceptional ages 36-37 vs 38-41 weeks). In group B, central latencies were prolonged, compared with controls (P < 0.001), but were not significantly correlated with long-term outcome in patients with moderate hypoxic-ischemic encephalopathy (n = 6). Neonatal SEP analysis thus is an objective and noninvasive method for assessing functional integrity of the somatosensory pathway. In term infants, SEPs are a valuable additional tool for early diagnosis of hypoxic-ischemic encephalopathy, but are not prognostic of neurodevelopmental long-term outcome in moderate hypoxic-ischemic encephalopathy.

Brain volume and metabolism in fetuses with congenital heart disease: evaluation with quantitative magnetic resonance imaging and spectroscopy

BACKGROUND

Adverse neurodevelopmental outcome is an important source of morbidity in children with congenital heart disease (CHD). A significant proportion of newborns with complex CHD have abnormalities of brain size, structure, or function, which suggests that antenatal factors may contribute to childhood neurodevelopmental morbidity.

METHODS AND RESULTS

Brain volume and metabolism were compared prospectively between 55 fetuses with CHD and 50 normal fetuses with the use of 3-dimensinal volumetric magnetic resonance imaging and proton magnetic resonance spectroscopy. Fetal intracranial cavity volume, cerebrospinal fluid volume, and total brain volume were measured by manual segmentation. Proton magnetic resonance spectroscopy was used to measure the cerebral N-acetyl aspartate: choline ratio (NAA:choline) and identify cerebral lactate. Complete fetal echocardiograms were performed. Gestational age at magnetic resonance imaging ranged from 25 1/7 to 37 1/7 weeks (median, 30 weeks). During the third trimester, there were progressive and significant declines in gestational age-adjusted total brain volume and intracranial cavity volume in CHD fetuses relative to controls. NAA:choline increased progressively over the third trimester in normal fetuses, but the rate of rise was significantly slower (P<0.001) in CHD fetuses. On multivariable analysis adjusted for gestational age and weight percentile, cardiac diagnosis and percentage of combined ventricular output through the aortic valve were independently associated with total brain volume. Independent predictors of lower NAA:choline included diagnosis, absence of antegrade aortic arch flow, and evidence of cerebral lactate (P<0.001).

CONCLUSIONS

Third-trimester fetuses with some forms of CHD have smaller gestational age- and weight-adjusted total brain volumes than normal fetuses and evidence of impaired neuroaxonal development and metabolism. Hemodynamic factors may play an important role in this abnormal development.

Disorders of the fetal circulation and the fetal brain

Even in the presence of normal placental function, cerebral oxygen-substrate supply may be disrupted by disturbances in the fetal circulation caused by anomalous cardiac development. The impact of these cardiac lesions is likely dictated primarily by the volume and oxygen-substrate composition of transverse aortic arch perfusion. Advances in fetal echocardiography, fetal Doppler ultrasound, and advanced fetal magnetic resonance imaging techniques capable of quantitative structural and functional measurements are providing major insights into the in vivo effects of these cardiac lesions on brain growth and development. The progress to date with the application of these techniques is reviewed in this article.

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.

Arterial switch with full-flow cardiopulmonary bypass and limited circulatory arrest: neurodevelopmental outcome

OBJECTIVES

Neonatal cardiac surgery has been associated with unfavorable neurodevelopmental events. We investigated a patient cohort operated on predominantly with full-flow cardiopulmonary bypass (150 mL x kg(-1) x min(-1), alpha-stat, alpha-blockade, median arrest = 6 minutes, temperature of 22 degrees C) as the major support strategy for neonatal arterial switch operations (transposition of the great arteries and intact ventricular septum).

METHODS

Seventy-four patients and "best-friend" control subjects were assessed 109 months (range, 48-166 months) postoperatively with general medical and neurologic evaluation, IQ testing, formal movement scores, and detailed parent-teacher behavioral-social reports. Fetal, neonatal, and perioperative data were collated.

RESULTS

The prevalence of perioperative seizures was 6.8% (4/5 cases occurring preoperatively). The incidence of all perioperative neurologic abnormalities was 20%. Patients who had a neurologic event were (as a group) older at the time of operation and had a lower arterial blood pH before the operation. Selected perioperative factors (not related directly to cardiopulmonary bypass variables) predicted early (before discharge) neurologic outcome in a multivariate model. At late assessment, patients were more likely than control subjects to have a mild neurologic abnormality (P = 0.002). Full-scale IQ scores (Wechsler Preschool and Primary Scale of Intelligence and Wechsler Intelligence Scale for Children-Third Edition) were higher in control subjects (101.9 [SD = 13] vs 108.6 [SD = 12], P =.0007), with both groups having scores greater than the population-based test means. Full-scale IQ scores related most significantly to years of paternal education (beta = 1.51, P =.0078) but were also influenced by perioperative neurologic abnormalities, birth weight, and circulatory arrest time. Patients had higher motor impairment scores (Movement Assessment Battery) than control subjects (P =.0004). Parents (Achenbach Child Development Checklist) assigned higher total social-behavioral competence scores to control subjects (P =.05). Teachers (Achenbach Teacher Report Form) suggested that patients were more likely to be perceived as having various speech and expressive language problems, as well as minor behavioral problems.

CONCLUSION

With the perioperative strategies used, not all survivors can be considered (neurodevelopmentally) normal at late follow-up, although the risk of important impairment is low. Perioperative events might have long-term prognostic value. On the basis of this study and published data regarding other strategies, continued application of full-flow cardiopulmonary bypass is justified, with the proviso that further investigation is required.

Predictors of developmental disabilities after open heart surgery in young children with congenital heart defects

OBJECTIVES

To determine the prevalence of persistent developmental impairments in children with congenital heart defects and to identify factors that enhance risk for an adverse outcome.

STUDY DESIGN

Eligible infants (n = 131) <2 years of age requiring open heart surgery were recruited prospectively. Subjects were assessed during surgery and again 12 to 18 months later with standardized developmental assessments and formal neurologic examinations.

RESULTS

Mean age at follow-up testing was 19.1 +/- 6.6 months. Assessments indicated that 41% had abnormal neurologic examinations. Gross and/or fine motor delays were documented in 42%, and 23% demonstrated global developmental delay. Univariate and multiple regression models identified the following factors increasing the risk for persistent developmental deficits: preoperative and acute postoperative neurodevelopmental status and microcephaly, type of heart lesion, length of deep hypothermic circulatory arrest, age at surgery, and days in the intensive care unit (P <.05).

CONCLUSIONS

Children with congenital heart defects commonly have ongoing neurologic, motor, and developmental deficits well after surgical correction. The cause is multifactorial and includes brain injury before, during, and after heart surgery.

Association between electroencephalographic findings and neurologic status in infants with congenital heart defects

Neurologic status is of concern in infants with congenital heart defects undergoing open heart surgery. The association between perioperative electroencephalography (EEG) with acute neurologic status and subsequent outcome was examined in a cohort of 60 infants. Preoperative EEG and neurologic examinations were performed within 1 to 2 days prior to surgery (n = 27) and postoperatively (n = 47). Prior to surgery, 15 of 27 infants had normal EEG, whereas 5 had epileptiform activity and 9 had disturbances in background activity that were primarily moderate (8/9) and diffuse (7/9). Postoperatively, only 17 of 47 infants had normal recordings. Newborns (<1 month) were more likely (P< .001) to demonstrate EEG abnormalities than infants. Epileptiform activity was documented in 15, whereas 28 had background abnormalities that were moderate-severe (22/28) and diffuse (20/28) in most. Epileptiform activity prior to surgery was always associated with an abnormal neurologic examination, and this association persisted postoperatively (86%). Moderate to severe background abnormalities in the postoperative EEG was also strongly associated with acute neurologic abnormalities (93%). Severe background abnormalities (n = 5) were 100% predictive of death or severe disability. Long-term follow-up revealed that all children with normal postoperative EEGs had positive neurologic outcomes (P = .04); however, there were many false positives. Perioperative EEG abnormalities increased the likelihood for acute neurologic findings, whereas normal recordings following surgery were reassuring with regard to a favorable outcome.

Neurodevelopmental status of newborns and infants with congenital heart defects before and after open heart surgery

BACKGROUND

Neurodevelopmental disabilities in children with congenital heart defects (CHDs) have been primarily attributed to intraoperative events without consideration of preoperative and postoperative factors.

OBJECTIVE

To describe the preoperative and postoperative neurodevelopmental status of newborns and infants with CHDs.

STUDY DESIGN

One hundred thirty-one children (56 newborns and 75 infants) were evaluated before and after surgery by using standardized neurobehavioral (newborn) and motor assessments (infant) and neurologic examinations.

RESULTS

In newborns, neurobehavioral abnormalities were documented in >50% before surgery, with abnormalities persisting in most after surgery. In infants, neurodevelopmental abnormalities were observed in 38% before surgery. There was a significant association between preoperative and postoperative neurodevelopmental status, with status remaining unchanged in most. Newborns with acyanotic heart lesions were more likely to demonstrate neurologic compromise than those with cyanotic defects. For infants, arterial oxygen saturations <85% were significantly associated with an abnormality. There was a trend for a longer circulatory arrest time to be associated with greater risk for neurologic sequelae in newborns, whereas prolonged cardiopulmonary bypass was an important risk factor for infants.

CONCLUSIONS

Neurodevelopmental abnormalities are common in young infants with CHDs and are often present before open heart surgery. These developmental concerns are clinically underappreciated. Early systematic developmental screening may be warranted in this population of interest.