Neurodevelopmental outcomes after congenital heart surgery and strategies for improvement. Curr Opin Cardiol. 2012;27:82-91. [PMID: 22274574 DOI: 10.1097/hco.0b013e328350197b]

Anesthetic neurotoxicity

All routinely utilized sedatives and anesthetics have been found neurotoxic in a wide variety of animal species, including non-human primates. Neurotoxic effects observed in animals include histologic evidence for apoptotic neuronal cell death and subsequent learning and memory impairment. Several cohort studies in neonates with significant comorbidities requiring surgical procedures early in life have also demonstrated abnormal neurodevelopmental outcomes. This article provides an overview of the currently available data from both animal experiments and human clinical studies regarding the effects of sedatives and anesthetics on the developing brain.

Neurodevelopmental outcome, psychological adjustment, and quality of life in adolescents with congenital heart disease

AIM

The aim of this study was to examine neurodevelopment, psychological adjustment, and health-related quality of life (HRQoL) in adolescents after bypass surgery for congenital heart disease (CHD) during early childhood.

METHOD

Fifty-nine adolescents (34 females, 25 males) with CHD were examined at a median age of 13 years 8 months (range 11 y 5 mo-16 y 11 mo). Outcome was assessed with the Wechsler Intelligence Scale for Children, (fourth edition); the Beery Test of Visual-Motor Integration; the Rey-Osterrieth Complex Figure Test; the Zurich Neuromotor Assessment; the Strengths and Difficulties Questionnaire; and the KIDSCREEN questionnaires. Results were compared with those of 40 age- and sex-matched healthy comparison individuals.

RESULTS

Outcome with regard to full-scale IQ, perceptual reasoning, and the working memory scale was poorer in patients with CHD than in the comparison group (all p ≤ 0.001). Visual perception, visuomotor integration (p ≤ 0.001), and executive functions (Rey figure copy: p=0.05) were also affected. Patients with CHD also had lower scores on all motor domains (p < 0.02) except static balance. Psychological adjustment was affected only in the 'peer relationship' domain (p=0.05). Quality of life was similar to that of typically developing peers.

INTERPRETATION

Adolescents with CHD may manifest persistent cognitive and motor impairments, while psychological adjustment and self-reported HRQoL are mostly typical. Thus, long-term neurodevelopmental evaluations are necessary to provide early educational and therapeutic support.

Extracorporeal membrane oxygenation for pediatric respiratory failure: History, development and current status

Extracorporeal membrane oxygenation (ECMO) is currently used to support patients of all ages with acute severe respiratory failure non-responsive to conventional treatments, and although initial use was almost exclusively in neonates, use for this age group is decreasing while use in older children remains stable (300-500 cases annually) and support for adults is increasing. Recent advances in technology include: refinement of double lumen veno-venous (VV) cannulas to support a large range of patient size, pumps with lower prime volumes, more efficient oxygenators, changes in circuit configuration to decrease turbulent flow and hemolysis. Veno-arterial (VA) mode of support remains the predominant type used; however, VV support has lower risk of central nervous injury and mortality. Key to successful survival is implementation of ECMO before irreversible organ injury develops, unless support with ECMO is used as a bridge to transplant. Among pediatric patients treated with ECMO mortality varies by pulmonary diagnosis, underlying condition, other non-pulmonary organ dysfunction as well as patient age, but has remained relatively unchanged overall (43%) over the past several decades. Additional risk factors associated with death include prolonged use of mechanical ventilation (> 2 wk) prior to ECMO, use of VA ECMO, older patient age, prolonged ECMO support as well as complications during ECMO. Medical evidence regarding daily patient management specifically related to ECMO is scant, it usually mirrors care recommended for similar patients treated without ECMO. Linkage of the Extracorporeal Life Support Organization dataset with other databases and collaborative research networks will be required to address this knowledge deficit as most centers treat only a few pediatric respiratory failure patients each year.

Neurodevelopmental outcome in children with congenital heart disease

Children with congenital heart disease (CHD) have multiple factors contributing toward their risk of later neurodevelopmental difficulties. With earlier diagnosis and improved survival rates, the management of CHD now includes the recognition of neurodevelopmental risks and optimisation of neurodevelopmental outcomes is emphasised. Neuroimaging studies have shown early differences in brain development for children with CHD, who then are vulnerable to additional brain injury in the perinatal period. For some children, complications and co-morbidities may further increase the risk of brain injury. Synthesis of multiple factors is necessary to estimate neurodevelopmental prognosis for an individual child. Long-term neurodevelopmental follow-up of children with CHD is warranted for early identification of and intervention for difficulties.

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.

Surgical technical performance scores are predictors of late mortality and unplanned reinterventions in infants after cardiac surgery

OBJECTIVE

We have previously shown that surgical Technical Performance Scores (TPS) are important predictors of early postoperative morbidity across a wide spectrum of procedures and that intraoperative recognition and intervention of residual defects resulted in improved outcomes. We hypothesized that these scores would also be important predictors of midterm outcomes.

METHODS

Neonates and infants aged younger 6 months were prospectively followed from the index surgery for a minimum of 1 year. The TPS were calculated using previously published criteria, including intraoperative course, predischarge echocardiograms or catheterizations, and clinical data, and graded as optimal, adequate, or inadequate. Case complexity was determined by the Risk Adjustment for Congenital Heart Surgery-1 category. The primary outcome was mortality, and the secondary outcome was the need for unplanned reinterventions. Outcomes were analyzed using nonparametric methods and a logistic regression model.

RESULTS

A total of 166 patients were included in our study, with 7 early deaths. The remaining 159 patients (Risk Adjustment for Congenital Heart Surgery-1 category 4-6, 76 [48%]; neonates, 78 [49%]) were followed for a minimum of 1 year after surgery. There were 14 late deaths or late transplantations and 55 late reinterventions. On univariate analysis, the TPS were associated with mortality (P < .001) and reintervention (P = .04). On logistic regression analysis, inadequate TPS was associated with late mortality (P < .001; odds ratio, 7.2; 95% confidence interval, 2.2-23.6), and Risk Adjustment for Congenital Heart Surgery-1 category (P = .004; odds ratio, 3.7; 1.5-8.8) at index surgery was associated with need for late unplanned reintervention.

CONCLUSIONS

Technical performance affects midterm survival after infant heart surgery. Inadequate TPS can be used to prospectively identify patients at ongoing risk of demise and the need for reintervention. An aggressive approach to diagnosing and treating residual lesions at the initial operation is warranted.