Early postoperative body temperature and developmental outcome after open heart surgery in infants

Research gaps in the neurodevelopmental assessment of children with complex congenital heart defects: a scoping review

Background

Children with congenital heart defects (CHD) are at risk for a range of developmental disabilities that challenge cognition, executive functioning, self-regulation, communication, social-emotional functioning, and motor skills. Ongoing developmental surveillance is therefore key to maximizing neurodevelopmental outcome opportunities. It is crucial that the measures used cover the spectrum of neurodevelopmental domains relevant to capturing possible predictors and malleable factors of child development.

Objectives

This work aimed to synthesize the literature on neurodevelopmental measures and the corresponding developmental domains assessed in children aged 1-8 years with complex CHD.

Methods

PubMed was searched for terms relating to psycho-social, cognitive and linguistic-communicative outcomes in children with CHD. 1,380 papers with a focus on complex CHD that reported neurodevelopmental assessments were identified; ultimately, data from 78 articles that used standardized neurodevelopmental assessment tools were extracted.

Results

Thirty-nine (50%) of these excluded children with syndromes, and 9 (12%) excluded children with disorders of intellectual development. 10% of the studies were longitudinal. The neurodevelopmental domains addressed by the methods used were: 53% cognition, 16% psychosocial functioning, 18% language/communication/speech production, and 13% motor development-associated constructs.

Conclusions

Data on social communication, expressive and receptive language, speech motor, and motor function are underrepresented. There is a lack of research into everyday use of language and into measures assessing language and communication early in life. Overall, longitudinal studies are required that include communication measures and their interrelations with other developmental domains.

Neuroprotective Drugs in Infants With Severe Congenital Heart Disease: A Systematic Review

Background: Perinatal and perioperative brain injury is a fundamental problem in infants with severe congenital heart disease undergoing neonatal cardiac surgery with cardiopulmonary bypass. An impaired neuromotor and neurocognitive development is encountered and associated with a reduction in quality of life. New neuroprotective drugs during surgery are described to reduce brain injury and improve neurodevelopmental outcome. Therefore, our aim was to provide a systematic review and best-evidence synthesis on the effects of neuroprotective drugs on brain injury and neurodevelopmental outcome in congenital heart disease infants requiring cardiac surgery with cardiopulmonary bypass.

Methods: A systematic search was performed in PubMed, Embase and the Cochrane Library (PRISMA statement). Search terms were “infants,” “congenital heart disease,” “cardiac surgery,” “cardiopulmonary bypass,” and “neuroprotective drug.” Data describing the effects on brain injury and neurodevelopmental outcome were extracted. Study quality was assessed with the Cochrane Risk of Bias Tool. Two reviewers independently screened sources, extracted data and scored bias. Disagreements were resolved by involving a third researcher.

Results: The search identified 293 studies of which 6 were included. In total 527 patients with various congenital heart diseases participated with an average of 88 infants (13–318) per study. Allopurinol, sodium nitroprusside, erythropoietin, ketamine, dextromethorphan and phentolamine were administered around cardiac surgery with cardiopulmonary bypass. Allopurinol showed less seizures, coma, death and cardiac events in hypoplastic left heart syndrome (HLHS) infants (OR: 0.44; 95%-CI:0.21–0.91). Sodium nitroprusside resulted in lower post cardiopulmonary bypass levels of S100ß in infants with transposition of the great arteries after 24 (p < 0.01) and 48 (p = 0.04) h of treatment. Erytropoietin, ketamine and dextromethorphan showed no neuroprotective effects. Phentolamine led to higher S100ß-levels and cerebrovascular resistance after rewarming and at the end of surgery (both p < 0.01). Risk of bias varied between studies, including low (sodium nitroprusside, phentolamine), moderate (ketamine, dextromethorphan), and high (erytropoietin, allopurinol) quality.

Conclusions: Allopurinol seems promising for future trials in congenital heart disease infants to reduce brain injury given the early neuroprotective effects in hypoplastic left heart syndrome infants. Larger well-designed trials are needed to assess the neuroprotective effects of sodium nitroprusside, erytropoietin, ketamine and dextromethorphan. Future neuroprotective studies in congenital heart disease infants should not only focus on the perioperative period, however also on the perinatal period, since significant brain injury already exists before surgery.

Protecting the infant brain during cardiac surgery: a systematic review

Prevention of brain injury during congenital heart surgery has focused on intraoperative and perioperative neuroprotection and neuromonitoring. Many strategies have been adopted as "standard of care." However, the strength of evidence for these practices and the relationship to long-term outcomes are unknown. We performed a systematic review (January 1, 1990 to July 30, 2010) of neuromonitoring and neuroprotection strategies during cardiopulmonary bypass (CPB) in infants of age 1 year or less. Papers were graded individually and as thematic groups, assigning evidence-based medicine and American College of Cardiology/American Heart Association (ACC/AHA) level of evidence grades. Consensus scores were determined by adjudication. Literature search identified 527 manuscripts; 162 met inclusion criteria. Study designs were prospective observational cohort (53.7%), case-control (21.6%), randomized clinical trial (13%), and retrospective observational cohort (9.9%). Median sample size was 43 (range 3 to 2,481). Primary outcome was evidence of structural brain injury or functional disability (neuroimaging, electroencephalogram, formal neurologic examination, or neurodevelopmental testing) in 43%. Follow-up information was reported in only 29%. The most frequent level of evidence was evidence-based medicine level 4 (33.3%) or ACC/AHA class IIB: level B (42%). The only intervention with sufficient evidence to recommend "the procedure or treatment should be performed" was avoidance of extreme hemodilution during CPB. Data supporting use of current neuromonitoring and neuroprotective techniques are limited. The level of evidence is insufficient to support effectiveness of most of these strategies. Well-designed studies with correlation to clinical outcomes and long-term follow-up are needed to develop guidelines for neuromonitoring and neuroprotection during CPB in infants.

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.

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.

Impaired neuroanatomic development in infants with congenital heart disease

OBJECTIVES

We performed a regional volumetric study of the brain using 3-dimensional magnetic resonance imaging in infants with congenital heart disease to search for variables in anatomic development of the brain that may be associated with functional impairment.

METHODS

Forty infants with congenital heart disease-17 infants with single ventricle physiology, 5 with transposition of great arteries, and 18 with ventricular septal defect-were studied prospectively by 3-dimensional magnetic resonance imaging of the brain several months after heart surgery.

RESULTS

The global volume of gray matter was significantly reduced in the patients with congenital heart disease compared with normal controls (P < .001), whereas no significant difference in the volume of white matter was observed. Further, the decrease in gray matter volume was more apparent in the frontal lobe than in the temporal lobe, especially in infants with single ventricle physiology or transposition of the great arteries. Multivariate analysis revealed that preoperative hypoxia is strongly associated with decreased frontal gray matter volume (P < .01), as well as a diagnosis of hypoplastic left heart syndrome (P < .05). Of note, frontal gray matter volume, which includes the motor area, correlated weakly with psychomotor developmental index scores (P < .01).

CONCLUSIONS

Brain developmental impairment occurs in many infants with congenital heart disease, especially in those who have preoperative hypoxia and critical congenital heart disease. This quantitative volumetric study encourages larger scale and longitudinal follow-up to elucidate the significance of impaired neuroanatomic development on functional outcome.

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.

Neurodevelopmental outcomes following congenital heart surgery

Advances in both surgical techniques and perioperative care have led to improved survival outcomes in infants and children undergoing surgery for complex congenital heart disease. An awareness is emerging that early and late neurological morbidities complicate the outcome of these operations. Adverse neurological outcomes after neonatal and infant cardiac surgery are related to both fixed and modifiable mechanisms. Fixed factors include many variables specific to the individual patient, including genetic predisposition, gender, race, socioeconomic status, and in utero central nervous system development. Modifiable factors include not only intraoperative variables (cardiopulmonary bypass, deep hypothermic circulatory arrest, and hemodilution) but also such variables as hypoxemia, hypotension, and low cardiac output. The purpose of this review is to examine these mechanisms as they relate to available outcome data.

Intracardiac temperature monitoring in infants after cardiac surgery

BACKGROUND

Hyperthermia after cerebral ischemia is associated with worse neurologic outcome. Our goals were 3-fold: (1) to describe the postoperative temperature course in infants after cardiac surgery, (2) to compare intracardiac temperature monitoring with traditional monitoring in infants, and (3) to determine variables that influence the patients' temperatures.

METHODS

Longitudinal temperature data were collected for 100 infants undergoing cardiac surgery. Intra-atrial, nasopharyngeal, esophageal, rectal, and axillary temperatures were recorded in all patients.

RESULTS

The mean age at the time of operation was 128 +/- 166 days, and the mean weight was 5.1 +/- 2.4 kg. Circulatory arrest was used for 54 patients. In the operating room, the maximum intra-atrial temperature (37.5 degrees C +/- 0.6 degrees C) was significantly greater than both the simultaneous esophageal temperature (36.9 degrees C +/- 1.9 degrees C, P = .03) and nasopharyngeal temperature (36.3 degrees C +/- 2.5 degrees C, P < .001). In the cardiac intensive care unit, intra-atrial temperature was significantly greater than both axillary and rectal temperatures. During the first 24 postoperative hours, intra-atrial temperature was greater than 38 degrees C in 48 (48%) patients, rectal temperature was greater than 38 degrees C in 36 (36%) patients, and axillary temperature was greater than 38 degrees C in 7 (7%) patients.

CONCLUSIONS

In patients less than 2 years of age undergoing cardiac surgery requiring cardiopulmonary bypass, intra-atrial temperature peaked 4 to 6 hours after leaving the operating room. Traditional methods of temperature monitoring significantly underestimate core temperature after cardiac surgery in infants. Use of intracardiac temperature monitoring might result in avoidance of cerebral hyperthermia.

Congenital Heart Surgery 2005: The brain: It’s the heart of the matter

Operative mortality after repair of even the most complex congenital heart lesions has become rare. As such, the gaze of the surgical team has been diverted beyond that of early survival to focus on decreasing early and late morbidity. Important and concerning information is accumulating delineating the vulnerability of the neonatal brain to injury as the result of congenital heart disease and/or the techniques employed to correct the lesions. For many years the prevention of neurologic injury associated with congenital heart surgery has concentrated on "unraveling" the mysteries of the deleterious effects of intentional brain ischemia (in the form of deep hypothermic circulatory arrest) and developing methods to interrupt the pathway of irreversible injury. In the late 1990s, alternative perfusion techniques were developed to minimize or theoretically avoid the use of deep hypothermic circulatory arrest where it was once thought to be mandatory. Simultaneously, the rather routine use of noninvasive, real-time, neurologic monitoring has provided surgical teams the opportunity to intervene and prevent brain injury , thus eliminating the historic reliance on postoperative surrogate markers to define the presence of brain injury. It is yet undetermined whether these strategies will translate into improved short- and long-term neurologic outcome. Common to all surgical disciplines is a trend that as mortality decreases for a particular disease process, focus is adjusted, and refinements in treatment protocols are designed to minimize morbidity of the disease and its treatment. This natural refining process of a discipline's maturation is increasingly present in the field of congenital heart surgery.

Central nervous system outcomes in children with complex congenital heart disease

PURPOSE OF REVIEW

To provide a brief overview of our current understanding of the types of neurodevelopmental sequelae in congenital heart disease survivors and to review the most recent studies from the past year, which have focused on 4 interrelated issues: (1) outcome studies, (2) the mechanism and etiology of central nervous system injury in children with CHD, (3) perioperative monitoring for brain injury, and (4) strategies for neuroprotection during cardiac surgery.

RECENT FINDINGS

As the number of survivors of surgery for complex congenital heart disease continues to rise, it is recognized that there is an increased incidence of adverse neurological outcomes in the survivors. In particular, a pattern similar to that seen in premature infants is emerging, including learning disabilities, behavioral abnormalities, inattention and hyperactivity. Imaging studies have revealed a high prevalence of structural brain abnormalities and periventricular leukomalacia, fetal and postnatal cerebral blood flow is abnormal, postnatal oxygen delivery is decreased, and intraoperative support techniques and postoperative low cardiac output are associated with cerebral hypoperfusion.

SUMMARY

The causes of these late developmental abnormalities are most likely sequential, cumulative and multifactorial.