Effects of age and ischemic times on biochemical evidence of myocardial injury after pediatric cardiac operations

High-sensitive troponinT, interleukin-8, and interleukin-6 link with post-surgery risk in infant heart surgery

BACKGROUND

This study focuses on biomarkers in infants after open heart surgery, and examines the association of high-sensitive troponin T (hs-cTnT), interleukin-6 (IL-6), and interleukin-8 (IL-8) with postoperative acute kidney injury (AKI), ventilatory support time and need of vasoactive drugs.

METHODS

Secondary exploratory study from a double-blinded clinical randomized trial (Mile-1) on 70 infants undergoing open heart surgery with cardiopulmonary bypass (CPB). In this sub-study, the entire study population was examined without considering the study drugs. The biomarkers' peak concentration (highest concentration at 2 or 6 h post-CPB) were used for statistical analyses.

RESULTS

Peak IL-8, hs-cTnT, and IL-6 occurred at 2 h post-CPB for 96%, 79%, and 63% of the patients, respectively. The odds ratio of developing AKI2-3 for IL-6 > 293 pg/mL was 23.4 (95% CI 5.3;104.0), for IL-8 > 100 pg/mL it was 11.5 (3.0;44.2), and for hs-cTnT >5597 pg/mL it was 6.1 (1.5; 24.5). In more than two third of the patients with the highest peak concentrations of IL-8, IL-6, and hs-cTnT, there was a need for ventilatory support for >24 h and use of vasoactive drugs at 24 h post-CPB, while in less than one third of the patients with the lowest peak concentrations of IL-8 and hs-cTnT such requirements were observed.

CONCLUSIONS

The peak biomarker concentrations and CPB-time strongly predicted AKI2-3, with IL-6 and IL-8 emerging as strongest predictors. Furthermore, our findings suggest that measuring hs-cTnT and IL-8 just 2 h post-CPB-weaning may assist in identifying infants suitable for early extubation and highlight those at risk of prolonged ventilation.

Predictive value of NT-proBNP and hs-TnT for outcomes after pediatric congenital cardiac surgery

BACKGROUND

The available evidence regarding the predictive value of troponins and natriuretic peptides for early postoperative outcomes in pediatrics is limited, controversial, and based on small sample sizes. The authors aimed to investigate the association of N-terminal pro B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponin T (hs-TnT) with the in-hospital adverse outcomes after congenital cardiac surgeries.

METHODS

A secondary analysis based on a prospective study of pediatric congenital heart disease (CHD) patients was conducted to investigate the association of NT-proBNP and hs-TnT tested within 6 h postoperatively with in-hospital adverse events. A multivariate logistic regression analysis with a minimum P value approach was used to identify the optimal thresholds of NT-proBNP and hs-TnT for risk stratification.

RESULTS

NT-proBNP and hs-TnT are positively correlated with cardiopulmonary bypass time, mechanical ventilation duration, and pediatric intensive care unit stay. The predictive performance of NT-proBNP is excellent for adverse events in both patients younger than 1 year [area under the curve (AUC): 0.771, 0.693-0.850] and those older than 1 year (AUC: 0.839, 0.757-0.922). However, hs-TnT exhibited a satisfactory predictive value solely in patients aged over 1 year. (AUC: 0.784, 0.717-0.852). NT-proBNP levels of 2000-10 000 ng/l [odds ratio (OR): 3.79, 1.47-9.76] and exceeding 10 000 ng/l (OR: 12.21, 3.66-40.80) were associated with a higher risk of postoperative adverse events in patients younger than 1 year. Patients older than 1 year, with NT-proBNP higher than 500 ng/l (OR: 15.09, 6.05-37.66) or hs-TnT higher than 1200 ng/l (OR: 5.50, 1.47-20.59), had a higher incidence of postoperative adverse events.

CONCLUSIONS

NT-proBNP and hs-TnT tested within postoperative 6 h demonstrated significant predictive value for postoperative adverse events in CHD patients older than 1 year. However, among CHD patients younger than 1 year, only NT-proBNP exhibited commendable predictive performance for postoperative adverse events.

Myocardial protection in paediatric cardiac surgery: building an evidence-based strategy

Cardioplegia is fundamental to the surgical repair of congenital heart defects by protecting the heart against ischaemia/reperfusion injury, characterised by low cardiac output and troponin release in the early postoperative period. The immature myocardium exhibits structural, physiological and metabolic differences from the adult heart, with a greater sensitivity to calcium overload-mediated injury during reperfusion. Del Nido cardioplegia was designed specifically to protect the immature heart, is widely used in North America and may provide better myocardial protection in children; however, it has not been commercially available in the UK, where most centres use St Thomas' blood cardioplegia. There are no phase 3 clinical trials in children to support one solution over another and this lack of evidence, combined with variations in practice, suggests the presence of clinical equipoise. The best cardioplegia solution for use in children, and the impact of age and other clinical factors remain unknown. In this Hunterian lecture, I propose an evidence-based strategy to improve myocardial protection during cardiac surgery in children through: (1) conducting multicentre clinical trials of established techniques; (2) improving our knowledge of ischaemia/reperfusion injury in the setting of cardioplegic arrest; (3) applying this to drive innovation, moving beyond current cardioplegia solutions; (4) empowering personalised medicine, through combining clinical and genomic data, including ethnic diversity; and (5) understanding the impact of cardioplegic arrest on the late outcomes that matter to patients and their families.

Postoperative Troponin Levels in Children Undergoing Open Heart Surgery With and Without Coronary Intervention

We aimed to characterize the ranges, temporal trends, influencing factors, and prognostic significance of postoperative troponin levels after congenital heart surgery. This single-center retrospective study included patients from 2006 to 2021 who had ≥ 1 postoperative troponin-T measurement collected within 96 h of congenital heart surgery (CHS). Patients were grouped as Anomalous Aortic Origin of the Coronary Artery-"AAOCA repair," or congenital heart surgery with "Other Coronary Interventions" other than AAOCA repair, or "No Coronary Intervention." In each group, information on concomitant surgery requiring one or more of the following-atriotomy, ventriculotomy, right ventricular muscle bundle resection, and/or septal myectomy-was collected. Clinical correlates of troponin values were analyzed in three postoperative windows: < 8, 8-24, and 24-48 h. The highest median [range] troponin levels (ng/mL) for the samples were 0.34 [0.06, 1.32] at < 8 h for "AAOCA repair," 1.35 [0.14, 12.0] at < 8 h for those undergoing CHS with "Other Coronary Interventions," and 0.87 [0.06, 25.1] at 8-24 h for those undergoing CHS with "No Coronary Interventions." Atriotomy was associated with higher median troponin levels in the AAOCA group at < 8 h (0.40 [0.31, 0.77] vs. 0.29 [0.17, 0.54], P = 0.043) and in the Other Coronary Intervention group at 8-24 h (1.67 [1.04, 2.63] vs. 0.40 [0.19, 1.32], P = 0.002). Patients experiencing major postoperative complications (vs. those who did not) had higher troponin levels in the AAOCA group as early as 8-24 h (0.36 [0.24, 0.57] vs. 0.21 [0.14, 0.33], P = 0.03). Similar findings were noted in the Coronary Intervention (2.20 [1.34, 3.90] vs. 1.11 [0.51, 2.90], P = 0.028) and No Coronary Intervention (2.2 [1.49, 15.1] vs. 0.74 [0.40, 2.34], P = 0.027) groups but earlier at < 8 h. In the AAOCA group, 2/18 (11%) troponin outliers experienced cardiac arrest in comparison to 0/80 (0%) non-outliers (P = 0.032). In the Other Coronary Intervention group, troponin outliers had longer median times to ICU discharge (10 vs. 4 days) and hospital discharge (21 vs. 10 days) (both P < 0.001). Postoperative troponin levels depend on a multitude of factors and may have prognostic value in patients undergoing congenital heart surgery with coronary interventions.

Myocardial injury and inflammatory response in percutaneous device closures of pediatric patent ductus arteriosus

Background

The percutaneous device closure of patent ductus arteriosus (PDA) is widely used in clinical practice, however full data on the changes in myocardial injury and systemic inflammatory markers’ levels after PDA in children are not fully reported.

Methods

We have conducted a retrospective analysis of the medical records of 385 pediatric patients in our hospital from January 2017 to December 2019. The patients were distributed into five groups. The first four (A, B, C and D) included patients divided by the type of the surgical closure methods, namely ligation, clamping, ligation-combined suturing and ligation-combined clamping, respectively. The fifth group E comprised of percutaneous device PDA patients. All recorded medical and trial data from the five groups were statistically studied.

Results

No serious complications in the patients regardless of the classification group were reported. Our results suggested that there were no considerable differences between the groups at the baseline (with all P > 0.05). Group E demonstrated a significantly smaller operative time (42.39 ± 3.88, min) and length of hospital stay (LOS) (4.49 ± 0.50, day), less intraoperative blood loss (7.12 ± 2.09, ml) while on the other hand, a higher total hospital cost (24,001.35 ± 1152.80, RMB) than the other four groups (with all P < 0.001). Interestingly, the comparison of the inflammatory factors such as white blood cells (WBC) count, C-reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6), as well as the myocardial injury markers (CKMB and troponin I) did not show a significant increase (P > 0.05) among the four groups. On the contrary, when the aforementioned factors and markers of all the surgical groups were compared to those in group E, we observed significantly higher speed and magnitude of changes in group E than those in groups A, B, C, and D (with all P < 0.001).

Conclusion

Although the percutaneous device closure of PDA is more comforting and drives fast recuperation in comparison to conventional surgery, it provokes myocardial injury and overall inflammation. Timely substantial and aggressive intervention measures such as the use of antibiotics before operation and active glucocorticoids to suppress inflammation and nourish the myocardium need be applied if the myocardial and inflammatory markers are eminent.

Postoperative Serum Troponin Trends in Infants Undergoing Cardiac Surgery

Troponin-I (TN-I) levels are elevated following pediatric cardiac surgery with speculation that particular patterns may have prognostic significance. There is lack of procedure-specific data regarding postoperative TN-I levels in infants undergoing cardiac surgery. We hypothesized that TN-I elevation varies with type of surgery and persistent elevation predicts poor prognosis. We prospectively measured serial TN-I levels (preoperatively, 4, 8, 12, 24, and 48 hours postoperatively) in 90 infants (age < 1 year) undergoing cardiac surgery: off cardiopulmonary bypass (CPB) (n = 15), on CPB (n = 43), and on CPB with ventricular incision (CPB with ventricular incision; n = 32). All patients had undetectable baseline TN-I levels. The area under the curve of TN-I levels over the 48-hour period was significantly different among the surgical groups (P < 0.002), and highest in patients with CPB with ventricular incision. Generally, TN-I levels peaked by 4 hours after surgery and returned to near-normal levels within 48 hours. A persistent TN-I rise beyond 8 hours after surgery was a strong predictor of postoperative hypoperfusion injury (defined as a composite endpoint of end-organ injury resulting from inadequate perfusion, odds ratio 21.5; P = 0.001) and mortality (30% in those with persistently high TN-I, compared with 3.5% in the remaining patients; P < 0.001), independent of patient age, anatomy and/or complexity of surgery, and level of postoperative support. Our data provide benchmark values for TN-I levels following cardiac surgery in infants. Extent of TN-I elevation correlates with type of surgery. Persistent TN-I elevation beyond 8 hours after surgery is strongly associated with postoperative hypoperfusion injury and mortality.

Cardiac injury biomarkers in paediatric age: Are we there yet?

The aim of this article is to evaluate the clinical utility of cardiac injury biomarkers in paediatric age. In December 2015, a literature search was performed (PubMed access to MEDLINE citations; http://www.ncbi.nlm.nih.gov/PubMed/ ). The search strategy included the following medical subject headings and text terms for the key words: "cardiac injury biomarkers", "creatine kinase-MB", "myoglobin", "troponin", "children", "neonate/s", "newborn/s", "infant/s" and echocardiography. In the paediatric population, troponins show a good correlation with the extent of myocardial damage following cardiac surgery and cardiotoxic medication and can be used as predictors of subsequent cardiac recovery and mortality. Elevation of cardiac injury biomarkers may also have diagnostic value in cases when cardiac contusion or pericarditis is suspected. Cardiac injury biomarkers are very sensitive markers for the detection of myocardial injury and have been studied in healthy newborns, after tocolysis, intrauterine growth restriction, respiratory distress and asphyxia. The proportion of newborns with elevated troponin was higher than that in ill infants, children, and adolescents and in healthy adults, suggesting that myocardial injury, although clinically occult, is common in this young age group. Results suggest that significant elevation of cord troponin is an excellent early predictor of severity of hypoxic-ischaemic encephalopathy and mortality in term infants. Cardiac biomarkers may also benefit centres without on-site echocardiography with evidence showing good correlation with echo-derived markers of myocardial function. Further studies are needed to better clarify the role of cardiac biomarkers in paediatric age and their correlation with echocardiographic parameters.

Specific Etiologies Associated With the Multiple Organ Dysfunction Syndrome in Children: Part 1

OBJECTIVE

To describe a number of the conditions associated with multiple organ dysfunction syndrome presented as part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development multiple organ dysfunction syndrome workshop (March 26-27, 2015).

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an expert from the field, issues relevant to the association of multiple organ dysfunction syndrome with a variety of conditions were presented, discussed, and debated with a focus on identifying knowledge gaps and research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by the relevant literature.

CONCLUSIONS

There is a wide range of medical conditions associated with multiple organ dysfunction syndrome in children. Traditionally, sepsis and trauma are the two conditions most commonly associated with multiple organ dysfunction syndrome both in children and adults. However, there are a number of other pathophysiologic processes that may result in multiple organ dysfunction syndrome. In this article, we discuss conditions such as cancer, congenital heart disease, and acute respiratory distress syndrome. In addition, the relationship between multiple organ dysfunction syndrome and clinical therapies such as hematopoietic stem cell transplantation and cardiopulmonary bypass is also considered. The purpose of this article is to describe the association of multiple organ dysfunction syndrome with a variety of conditions in an attempt to identify similarities, differences, and opportunities for therapeutic intervention.

Cardiopulmonary Bypass-Induced Inflammatory Response: Pathophysiology and Treatment

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the pro-inflammatory response to the cardiopulmonary bypass circuit, the impact of ischemia reperfusion injury on post-operative organ function, the compensatory anti-inflammatory response and the evidence for immune-modulatory strategies and their impact on outcomes.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSION

Innovations such as the development of more biocompatible surfaces and miniaturized circuits, as well as the increasing expertise of surgeons, anesthesiologists and perfusionists has transformed cardiac surgery and the use of cardiopulmonary bypass into a relatively routine procedure with favorable outcomes. Despite these refinements, the attendant inflammatory response to bypass, ischemia reperfusion injury and the compensatory anti-inflammatory response contribute to post-operative morbidity and mortality. Additional studies are needed to further delineate the impact of immunomodulatory strategies on outcomes.

Oxidative Stress after Surgery on the Immature Heart

Paediatric heart surgery is associated with increased inflammation and the production of reactive oxygen species. Use of the extracorporeal cardiopulmonary bypass during correction of congenital heart defects generates reactive oxygen species by various mechanisms: haemolysis, neutrophil activation, ischaemia reperfusion injury, reoxygenation injury, or depletion of the endogenous antioxidants. The immature myocardium is more vulnerable to reactive oxygen species because of developmental differences compared to the adult heart but also because of associated congenital heart diseases that can deplete its antioxidant reserve. Oxidative stress can be manipulated by various interventions: exogenous antioxidants, use of steroids, cardioplegia, blood prime strategies, or miniaturisation of the cardiopulmonary bypass circuit. However, it is unclear if modulation of the redox pathways can alter clinical outcomes. Further studies powered to look at clinical outcomes are needed to define the role of oxidative stress in paediatric patients.

Ultrastructural and metabolic features of stress-adaptive rearrangements of myocardium in infants after surgery-induced up-regulation of lipoperoxidation processes

Surgical correction of complicated congenital heart disease in infants is terminated by postischemic reperfusion of myocardium accompanied with closure of more than 20% microvessels in the coronary bed by edematous endothelial cells, their bleb-like fragments, and aggregates of the blood formed elements. Degradation of the transmission capacity of the coronary microvessels developed in parallel with moderation of activity of the antiradical protection enzymes and positively correlated with the level of LPO secondary products, whose elevation during the surgery stages was not reduced by catalase activation.

Comparison of cardioprotective effects of volatile anesthetics in children undergoing ventricular septal defect closure

BACKGROUND

Volatile anesthetic agents may precondition the myocardium and protect against ischemia and infarction. Preconditioning by volatile anesthetic agents is well documented in adults but is underinvestigated in children. The present study compares the effect of preconditioning in children by three volatile anesthetic agents along with several other variables associated with cardioprotection.

METHOD

Eighty children scheduled for ventricular septal defect closure under cardioplegic arrest were assigned to preconditioning for five minutes after commencement of cardiopulmonary bypass (CPB) with one minimum alveolar concentration (MAC) of one of the following agents: isoflurane, sevoflurane, desflurane, or placebo (oxygen-air mixture). The plasma concentration of creatine kinase MB (CK-MB) was determined after initiation of CPB, and again 6 and 24 hours after admission to the intensive care unit (ICU) after surgery. Duration of inotropic support, mechanical ventilation, and length of ICU stay in all the groups were also recorded.

RESULTS

Preconditioning with isoflurane, sevoflurane, and desflurane was associated with significantly decreased postoperative release of CK-MB as compared to placebo group at 6 (group 1: 237.2 ± 189, group 2: 69.8 ± 15.8, group 3: 64.7 ± 37.8, and group 4: 70.4 ± 26.7) and 24 hours (group 1: 192.4 ± 158.2, group 2: 67.7 ± 25.0, group 3: 85.7 ± 66.8, and group 4: 50.4 ± 31.6) after admission to ICU. No significant differences were observed in the CK-MB levels among the three volatile anesthetic agents. Duration of inotropic support, mechanical ventilation, and length of ICU stay were greater in placebo group as compared to other groups without reaching statistical significance.

CONCLUSION

Volatile anesthetic appear to provide definite cardioprotection to pediatric myocardium. No conclusion can be drawn regarding the best preconditioning agent among isoflurane, sevoflurane, and desflurane.

Cardiac troponin I after cardiopulmonary bypass in infants in comparison with older children

OBJECTIVE

At the present time, there is a trend towards performing open heart surgery at a younger age. Myocardium of infants has been thought to be more vulnerable to cardiopulmonary bypass in comparison with adults. For this study, we evaluated the degree of myocardial injury by measurement of cardiac troponin levels in infants in comparison with older children for similar surgeries.

METHODS

Serum was collected before bypass, after bypass, and daily after surgery and serum cardiac troponin I level (micrograms per litre). The demographic data, cardiac diagnoses, types of surgery performed, and peri-operative parameters were collected.

RESULTS

Of the 21 children enrolled consecutively, five were infants. Among the 21 patients, four patients had post-operative peak troponin values greater than 100 (three were infants) and all four patients survived and had normal left ventricular systolic function upon discharge echocardiogram. The five infants had peak troponin levels of 222.3, 202, 129, 26.7, and 82.3. The post-operative peak troponin levels were significantly higher in infants (mean 132.5 with a standard deviation of 81.6) than in the older children (mean 40.3 with a standard deviation of 33.4), although there was no significant difference in bypass time, bypass temperature, cross-clamp time, or the length of stay in the intensive care unit between the two age groups.

CONCLUSIONS

Higher troponin release is seen in infants in comparison with older children after bypass for similar surgeries. A troponin level greater than 100 after bypass does not necessarily predict death or a severe cardiovascular event in the very young.

Early elevation of cardiac troponin I is predictive of short-term outcome in neonates and infants with coronary anomalies or reduced ventricular mass undergoing cardiac surgery

OBJECTIVE

The present study aimed to assess the usefulness of routine monitoring of cardiac troponin I concentrations within 24 hours of surgery (cTn-I<24h) in neonates and infants undergoing cardiac surgery.

METHODS

The added predictive ability of a high peak cTn-I<24h (within the upper quintile per procedure) for a composite outcome, including 30-day mortality and severe morbidity, was assessed retrospectively. The predicted risk for the composite outcome was estimated from a logistic regression model including preoperative and intraoperative variables. Adding a high peak cTn-I<24h to the risk model resulted in reclassification of the predicted risk. It also allowed quantification of the improvement in reclassification and discrimination by the difference between c-indexes, the Net Reclassification and the Integrated Discrimination Indexes (NRI and IDI).

RESULTS

Overall, 1023 consecutive patients were included. Adding a high peak cTn-I<24h to the model resulted in no improvement in reclassification or discrimination in the overall population (difference between c-indexes: 0.011 [-0.004 to 0.029], NRI = 0.06, P = .22, IDI = 0.02, P = .06), except in a subgroup of patients undergoing the arterial switch operation with or without ventricular septal defect closure and/or aortic arc repair, anomalous origin of the left coronary artery from the pulmonary artery repair, truncus arteriosus repair, Norwood procedure, and Sano modification, in whom NRI = 0.23 (P = .005) and IDI = 0.05 (P < .001).

CONCLUSIONS

Patients with coronary anomalies and patients with reduced ventricular mass should benefit from the routine monitoring of cTn-I concentrations after surgery for congenital cardiac disease.

Cardiac troponin I release after transcatheter atrial septal defect closure correlated with the ratio of the occluder size to body surface area

BACKGROUND

Cardiac troponin I (cTnI) is a very specific and sensitive marker of myocardial injury. The degree of myocardial injury associated with transcatheter atrial septal defect (ASD) closure in children is unknown.

METHODS

In a longitudinal study on children with ASD, cTnI serum concentrations were measured after transcatheter ASD closure. Implantation success, complications, and latest patient follow-up were described.

RESULTS

We inserted 73 Amplatzer septal occluders in 73 patients. Of these, we excluded two patients in whom the device embolized to the right ventricle the day after deployment. The median age was 4.5 years (range, 1.1-18.0) with 20 boys and 51 girls (male:female ratio, 1:2.6). The mean ASD size was 17 ± 7 mm, and device size ranged from 7 mm to 38 mm. The Amplatzer size/body surface area ratio was validated by demonstrating positive correlation with cTnI elevation. In children who had a successful attempt, 30 samples had a cTnI value higher than 1.0 μg/L l at 6 hours after procedure. Six patients had a significant release of cTnI greater than normal limits (mean level of 1.51 ± 0.26 μg/L).

CONCLUSION

In our study, transcatheter ASD closure induced minor myocardial lesion, the extent of which depended on the ratio of the occluder size to body surface area (p<0.05) but not on the patient's weight or preprocedural left ventricular ejection fraction.

Immediate hypothermia reduces cardiac troponin I after hypoxic-ischemic encephalopathy in newborn pigs

Neonatal hypoxic-ischemic encephalopathy (HIE) is a clinically defined neurological condition after lack of oxygen and often associated with cardiac dysfunction in term infants. Therapeutic hypothermia (HT) after birth is neuroprotective in infants with HIE. However, it is not known whether HT is also cardioprotective. Four newborn pigs were used in the pilot study and a further 18 newborn pigs [randomly assigned to 72 h normothermia (NT) or 24 h HT followed by 48 h NT] were subjected to global HIE insults. Serum cTnI was measured before and post the HIE insult. Blood pressure, inotropic support, blood gases, and heart rate (HR) were recorded throughout. Cardiac pathology was assessed from histological sections. Cooling reduced serum cTnI levels significantly in HT pigs by 6 h (NT, 1.36 ± 0.67; HT, 0.34 ± 0.23 ng/mL; p = 0.0009). After rewarming, from 24 to 30 h postinsult, HR and cTnI increased in the HT group; from HR[24 h] = 117 ± 22 to HR[30 h] = 218 ± 32 beats/min (p = 0.0002) and from cTnI[24 h] = 0.23 ± 0.12 to cTnI[30 h] = 0.65 ± 0.53 ng/mL, (p = 0.05). There were fewer ischemic lesions on cardiac examination (37%) in the HT group compared with the NT group (70%). HT (24 h) pigs did not have the postinsult cTnI increase seen in NT-treated pigs. There was a trend that HT improved cardiac pathology in this 3-d survival model.

Ischemic myocardial injuries after cardiac malformation repair in infants may be associated with oxidative stress mechanisms

BACKGROUND

Despite advances in pediatric cardiac surgery, perioperative myocardial injury can be the major determinant of postoperative dysfunction after cardiac surgery. This study investigated the pathology-related differences in 29 infants with congenital heart disease that led to death. The infants were treated at the University Hospital of Ribeirão Preto, Brazil.

METHODS

The patients were divided into four groups: Group 1, 16 infants who underwent operations for congenital heart disease on cardiopulmonary bypass; Group 2, four infants who underwent off-cardiopulmonary bypass operations for congenital heart disease; Group 3, nine infants who died from congenital heart disease prior to surgical treatment; and Group 4 (control group), five infants with no congenital heart disease and who died from other causes. The myocardial injuries and oxidative stress mechanisms were assessed by histopathology and immunohistochemistry and were quantified by morphometrical analyses.

RESULTS

Contraction band necrosis and dystrophic calcification were found primarily in infants of Group 1. Coagulation necrosis and healing were prominent in Group 2, while infants without repair (Group 3) showed mainly colliquative myocytolysis. Apoptotic cells were more prominent in the operative groups. The control group showed no significant myocardial lesions. Lipid peroxidation was the principal mechanism of oxidative stress accounting for the myocardial lesions.

CONCLUSION

The diversity of the lesions observed in these hearts seemed to indicate a large spectrum of cell damage due to inadequate myocardial perfusion, especially when these infants underwent surgery. Oxidative mechanisms could be a common mediator in the pathogenesis of myocardial injuries, mediated by peroxidation of the membrane phospholipids and resulting in changes in the permeability of the cell membrane, cell death, and intracellular calcium overload. Furthermore, an immature and often hypertrophied myocardium may promote unfavorable conditions, leading to heart failure and a lethal outcome.

Myocardial transcriptional profiles in a murine model of sepsis: evidence for the importance of age

BACKGROUND

Age influences outcome of sepsis and septic shock. The mechanism of this age-dependent vulnerability to sepsis remains largely unknown. Because much of the mortality and morbidity associated with sepsis and septic shock is the result of severe derangements in the cardiovascular system, it is possible that the myocardium responds to injury in a developmentally influenced manner. We hypothesized that analysis of cardiac RNA expression profiles may differentiate between the myocardial response to sepsis in young and old mice.

METHODS AND RESULTS

Sixteen FVB/N male mice were stratified based on age. Young animals were 6 wks old, correlating to 4 to 6 human years, and aged animals were 20 months old correlating to 70 to 80 human years. Animals underwent either cecal ligation and puncture to produce polymicrobial sepsis or a sham operation. Both ventricles were excised after kill at 24 hrs. There were 53 genes that differed in RNA abundance between the four groups (false discovery rate of 0.005, p < 0.00001). Additionally, four genes were associated with an age-dependent response to sepsis: CYP2B2 (cytochrome P450, family 2, subfamily B, polypeptide 6), VGLL2 (vestigial like 2), and PAH (phenylalanine hydroxylase). The fourth gene is an expressed sequence tag, the function of which is related to the cytochrome P450 family. These genes play roles in phenylalanine, tyrosine, tryptophan, and fatty acid metabolism.

CONCLUSIONS

This report describes the transcriptional response of the heart to sepsis. In addition, our findings suggest that these differences are in part age-dependent and serve as hypothesis generation.

N-terminal probrain natriuretic peptide level inversely correlates with cardiac index after arterial switch operation in neonates

BACKGROUND

Natriuretic peptide levels are associated with cardiac output and ventricular function. We hypothesized that concomitant measurement of the peptide fragments and the hemodynamic parameters could elucidate the associations of these parameters after pediatric cardiac surgery.

METHODS

After approval of the institutional review board and parents' informed consent, we investigated the clinical data of eight neonates undergoing correction of transposition of the great arteries. We measured the level of N-terminal fragments of prohormones of atrial and brain natriuretic peptides (NT-proANP, NT-proBNP) preoperatively, postoperatively and 12, 24, 48, and 72 h after arrival in the intensive care unit. The hemodynamic status was assessed by transpulmonary thermodilution at the same time points. Creatinine and other laboratory values were analyzed in the first 48 h postoperatively.

RESULTS

NT-proBNP levels were inversely correlated with cardiac index (CI, r = -0.47, P = 0.030), stroke volume index (r = -0.65, P = 0.005), and global end-diastolic volume index (GEDI; r = -0.63, P = 0.011). There was strong inverse correlation between the change of NT-proBNP levels and the change of CI between two consecutive measurements during the postoperative period (r = -0.79, P = 0.001). The NT-proBNP level 12 h after surgery was strongly correlated with the creatinine level of the postoperative 24th hour (r = 0.81, P = 0.014).

CONCLUSIONS

NT-proBNP correlated with the hemodynamic parameters and with the severity of renal dysfunction. Therefore, NT-proBNP is a reliable indicator of the circulatory state and the severity of a low output syndrome after arterial switch operation in neonates.

Segmental Wall-Motion Abnormalities After an Arterial Switch Operation Indicate Ischemia

We prospectively studied 29 consecutive neonates undergoing an arterial switch operation to determine if segmental wall motion abnormalities (SWMA) represented myocardial ischemia. Intraoperative transesophageal echocardiogram was recorded at baseline and twice after cardiopulmonary bypass. Cardiac troponin I (cTnI) levels were measured before sternal incision and 3, 6, 12, 24, 48, and 72 h after removal of the aortic cross-clamp. Immediate postoperative Holter and 15-lead electrocardiograms (ECG) were evaluated for ischemia. Transthoracic echocardiograms were obtained before hospital discharge. At bypass termination, immediately after protamine administration, segmental wall motion was normal in nine neonates and abnormal in 20. SWMA were transient in five and present at the time of chest closure in 15 neonates. Neonates in whom SWMA were present at chest closure had more segments involved than those in whom SWMA were transient (P > 0.001). Neonates with SWMA at chest closure had higher cTnI levels postoperatively versus neonates with normal wall motion (P = 0.02). Postoperative ECG data were available in 26 neonates. There was ECG evidence of myocardial ischemia in two of eight neonates with normal wall motion, one of five with transient SWMA, and nine of 13 with SWMA at chest closure. CTnI levels at 12, 24, and 48 h and intraoperative SWMA were predictive of postoperative SWMA. We believe these data indicate that SWMA, which persist at the completion of an arterial switch operation, and which are present in multiple myocardial segments, correlate with myocardial ischemia. Further follow-up of these patients is needed to determine if increased intraoperative myocardial ischemia correlates with long-term outcomes.

Cardiac Troponin T Levels for Risk Stratification in Pediatric Open Heart Surgery

BACKGROUND

Cardiac troponin T has been found to be accurate predictor of complications and adverse clinical events after pediatric cardiac surgery. Contrary to adult cardiac surgery, the relationship of troponin T to patient survival after pediatric heart surgery has not been previously studied. The purpose of this study was to determine whether troponin T could predict death after pediatric open cardiac surgery.

METHODS

This was a retrospective cohort study in which data from 1001 consecutive children having cardiac surgery during a 5-year period were studied. Perioperative variables that could influence death at 30 postoperative days were evaluated.

RESULTS

Multivariate analysis, using a forward stepwise logistic regression, showed that troponin T measured on the first postoperative day was a strong independent predictor of death at 30 days. Level of troponin T greater than 5.9 microg/L on the first postoperative day predicted death (odds ratio, 10.7; 95% confidence interval: 5.2 to 22.1) as did admission lactate level greater than 5.2 mmol/L (odds ratio, 22.2; 95% confidence interval: 9.7 to 50.8) No other variable, including postoperative creatine kinase-MB mass concentration, age, diagnosis, surgical procedure, presence of cyanosis, chromosomal anomaly or ventriculotomy, duration of cardiopulmonary bypass, or aortic cross-clamp, had any independent effect on 30-day survival.

CONCLUSIONS

Cardiac troponin T level on the first postoperative day is a powerful independent risk marker of death in pediatric cardiac surgery.

Sodium pump reduction correlates with aortic clamp time in pediatric heart surgery

Myocardial depression after cardiac surgery is modulated by cardiopulmonary bypass (CPB) and the underlying heart disease. The sodium pump is a key component for myocardial function. We hypothesized that the change in sodium pump expression during CPB correlates with intraoperative and postoperative laboratory and clinical parameters in neonates and children with various congenital heart defects. Sodium pump isoforms alpha1 (ATP1A1) and alpha3 (ATP1A3) mRNA expression in right atrial myocardium, excised before and after CPB, was quantified. Groups were assigned according to presence (VO group, n = 8) or absence (NO group, n = 8) of right atrial volume overload. CPB and aortic clamp time correlated with postoperative troponin-I values and ICU stay. ATP1A1 (P = 0.008) and ATP1A3 (P = 0.038) mRNA expression were significantly reduced during CPB. Longer aortic clamp times were associated with lower postoperative ATP1A1 (P = 0.045) and ATP1A3 (P = 0.002) mRNA expression. Low postoperative ATP1A1 (P = 0.043) and ATP1A3 (P = 0.002) expressions were associated with high troponin-I values. These results were restricted to the VO group. No correlation of sodium pump mRNA expression was found with the duration of ICU stay or ventilation. The postoperative troponin-I and clinical parameters correlated with the length of CPB, regardless of volume overload. In contrast, only dilated right atrium seemed to be susceptible to CPB in terms of sodium pump expression, showing a reduction during the operation and a correlation of sodium pump with postoperative troponin-I values.

Recent developments in the perioperative management of the paediatric cardiac patient

PURPOSE OF REVIEW

Survival of infants born with complex cardiac anomalies has dramatically improved, and the growing population of patients with congenital heart disease reaching adulthood has resulted in an increased incidence of long-term complications related to the perioperative period. This review focuses on recent advances in strategies to prevent, detect, treat, or predict early and late complications arising from open heart surgery for congenital heart disease.

RECENT FINDINGS

Aprotinine and recombinant factor VIIa may effectively reduce the risk of excessive perioperative bleeding, and the use of steroids, complement component C4A, heparin-coated circuits, and modified ultrafiltration may play a role in the control of the postoperative inflammatory response. Milrinone is becoming increasingly popular in the prevention and treatment of the reduced postoperative cardiac output, and extracorporeal life support has become a well established and successful form of support for postoperative myocardial dysfunction, even in the functionally univentricular heart. In recent years interest increased in optimizing myocardial protection using contents-differentiated and temperature-differentiated blood cardioplegia and in optimizing cerebral protection using a higher haematocrit during bypass and by using selective regional perfusion in favour of circulatory arrest.

SUMMARY

Hearts can be mended, but salvation of hearts and brains needs further rigorous attention.

Frequency of clinically unsuspected myocardial injury at a children's hospital

BACKGROUND

Ill children are at risk but rarely screened for myocardial injury. The frequency of such injury in ill children is unknown. Elevated levels of plasma cardiac troponin I (cTnI) can detect subclinical myocardial injury.

METHODS

We measured cTnI levels from 283 Children's Hospital, Boston patients (median age 2.10 years, range 0.13-22.4 years) seen in an outpatient or emergency clinic without clinically apparent cardiac disease. We took > or = 0.5 ng/mL as an indication of myocardial injury. We also measured plasma creatine kinase-MB, total creatine kinase, and myoglobin, and performed a chart review.

RESULTS

Fifteen (7.8%) of the 193 acutely ill children and 4 (4.4%) of the 90 well children had an elevated cTnI level (P = .44). Within the acutely ill group, the children with elevated cTnI were younger and had lower mean hemoglobin and hematocrit levels. Cardiac troponin I levels correlated with creatine kinase-MB (r = 0.22; P < .001) but not with creatine kinase or myoglobin. The 4 children with cTnI > 0.89 ng/mL, who also had plasma cardiac troponin T measured, showed cardiac troponin T elevations that were consistent with unstable angina levels in adults. Four children had high-level cTnI elevations (> 2 ng/mL) consistent with acute myocardial infarction levels in adults.

CONCLUSIONS

Elevated cTnI levels occur in children without clinically apparent cardiac disease and can be at adult unstable angina or acute myocardial infarction levels. Prospective studies to determine the clinical significance of these findings and their relationship to the development of cardiomyopathy are warranted.

Free Amino Acids in Hearts of Pediatric Patients With Congenital Heart Disease: The Effects of Cyanosis, Age, and Pathology

BACKGROUND

The immature heart has a much greater dependence than the adult heart on amino acid transamination in determining its ischemic tolerance. Compared with adult hearts, experimental models of the immature heart have quantified higher resting concentrations of free amino acids (AA) which are depleted by acute hypoxia. However, we have found no clinical studies that have looked at the free AA profile of the immature human heart or the effects of cyanosis, age, and pathology upon this.

METHODS

One hundred eighty-one pediatric patients (37 cyanotic, 144 acyanotic) undergoing open-heart surgery were recruited. Myocardial biopsies were collected prior to ischemia and analyzed for free AAs (eg, glutamate, aspartate) using high-performance liquid chromatography. The effects of cyanosis, age, and pathology on amino acid concentrations were estimated by multiple regression modeling with and without controlling for diagnosis; the effects of age and pathology were estimated only in acyanotic children.

RESULTS

Alanine concentrations were about 20% higher in cyanotic than acyanotic patients (p = 0.04). Cyanosis was not associated with any other amino acid levels. In acyanotic patients, after controlling for diagnosis, concentrations of glutamate, aspartate, and alanine decreased from birth to about 8 to 10 years, then started to increase again (p < 0.05 for both linear and quadratic terms); concentrations of taurine and the branched chain AAs decreased steadily with increasing age (p < 0.05). There were significant effects of pathology on glutamate (p = 0.006), glutamine (p = 0.003), and branched chain AA (p = 0.004) levels.

CONCLUSIONS

There is no evidence that chronic hypoxia depletes endogenous AAs. Young age is associated with higher resting AA levels.

Cardiopulmonary bypass reduces atrial Na+-K+-ATPase expression in children

Cardiopulmonary bypass (CPB) may induce serious side effects, potentially leading to myocardial failure. The Na(+)-K(+)-ATPase is a key component for myocardial function. Due to its developmental regulation, results from adult studies cannot be adopted to the situation in childhood. Right atrial myocardium from patients with left-to-right shunts at atrial level (VO, n=8) and those without (NO, n=8) was excised during heart surgery before and after CPB. Na(+)-K(+)-ATPase isoforms ATP1A1 (p=0.008) and ATP1A3 (p=0.038) decreased during CPB, which decrease was restricted to the VO group. This study highlights the importance of the underlying heart defect for susceptibility to the effects of CPB, showing a reduced Na(+)-K(+)-ATPase mRNA expression only in patients with left-to-right shunts on the atrial level. This seemed to be an early molecular event, as apart from one, none of the patients showed heart failure before or after surgery.

Serum Cardiac Troponin-I Elevation in Neonatal Cardiac Surgery is Lesion-Dependent

OBJECTIVE

Serum cardiac troponin-I (cTn-I) is a marker for myocardial injury in adults that undergoes developmental isoform change. To determine its utility as a myocardial injury marker in neonates, the authors examined the perioperative pattern of cTn-I elevation in neonates undergoing surgical repair for hypoplastic left-heart syndrome (HLHS) and transposition of great arteries (TGA).

DESIGN

A prospective cohort study.

SETTING

The study was performed in a tertiary teaching hospital that is a major referral center for congenital cardiac surgery.

PATIENTS

Forty-five neonates were enrolled, 17 with HLHS, 15 with TGA with intact septum (TGA + IVS), 8 with TGA with ventricular septal defect (TGA + VSD), and 5 neonates undergoing extracardiac surgery who did not require cardiopulmonary bypass (CPB).

INTERVENTIONS

None.

RESULTS

Preoperative cTn-I was elevated in all neonates undergoing cardiac surgery with CPB. Increases in postoperative cTn-I correlated with duration of aortic cross-clamp application and CPB. Peak elevation in serum cTn-I occurred between 6 and 24 hours postoperatively in all neonates after cardiac surgery. The perioperative pattern of cTn-I was different in TGA + VSD (peak cTn-I = 10.9 +/- 5.9 ng/mL) compared with HLHS (peak cTn-I = 4.62 +/- 3.4 ng/mL) and TGA + IVS (peak cTn-I = 4.46 +/- 3.5 ng/mL).

CONCLUSION

It was found that perioperative elevations in serum cTn-I in neonates with TGA and HLHS were influenced by duration of aortic cross-clamp application, CPB, and the presence of VSD.

Cardiac troponin I release after transcatheter atrial septal defect closure depends on occluder size but not on patient's age

OBJECTIVE

To examine whether transcatheter closure of secundum atrial septal defect (ASD) with the Amplatzer septal occluder leads to more myocardial injury in children than in adults.

DESIGN

In a prospective study with children and adults cardiac troponin I (cTnI) serum concentrations were determined by immunoassay (AxSYM, Abbott Laboratories) before, during, and up to 20 months after surgical or transcatheter ASD closure.

PATIENTS

Four groups of patients were studied: transcatheter ASD closure (group 1: 22 children, age range 3.26-14.7 years; group 2: 22 adults, 18.0-67.3 years), surgical ASD closure (group 3: 18 children, 3.12-13.5 years), and diagnostic catheterisation (group 4: 12 children, 2.68-15.0 years).

RESULTS

cTnI concentrations were significantly increased after occluder implantation with higher serum concentrations in children than in adults (immediately after implantation: group 1, 3.2 (4.4) microg/l; group 2, 1.1 (4.2) microg/l; four hours after implantation: group 1, 4.8 (5.0) microg/l; group 2, 1.7 (2.3) microg/l; both p < 0.01, group 1 v group 2; one day after implantation: group 1, 3.0 (5.7) microg/l; group 2, 2.2 (5.2) microg/l) but were less than 20% of those after surgical ASD closure (group 3; p < 0.001) where the highest cTnI concentration was found (37.1 (26.3) microg/l). Diagnostic catheterisation (group 4) was not associated with detectable cTnI increase. From the cTnI concentrations the total amount of cTnI released after ASD closure was estimated for each patient. This was dependent on the size of the occluder (p < 0.05) but not on the patient's age or procedural duration.

CONCLUSION

In regard to interventional ASD closure our data do not provide evidence that the child's myocardium is more vulnerable. Transcatheter ASD closure induces minor myocardial lesion, the extent of which depends on the size of the Amplatzer septal occluder but is irrespective of the patient's age.

The dependence of myocardial damage on age and ischemic time in pediatric cardiac surgery

OBJECTIVE

Heart fatty acid-binding protein is a rapid indicator for assessment of myocardial damage in cardiac surgery. The purpose of this study was to investigate the effects of age and ischemic time on the biochemical evidence and clinical outcomes of myocardial damage in pediatric cardiac surgery.

METHODS

A prospective observational cohort study conducted over 2.5 years was performed in 98 consecutive patients (51 infants and 47 children) undergoing cardiac surgery for ventricular septal defects. Serial measurements of serum levels of heart fatty acid-binding protein and the respective areas under the curve were obtained, with particular reference to age and aortic crossclamp time. Assessment of clinical outcomes included inotropic support, ventilatory support, and intensive care unit stay.

RESULTS

There was a linear dependence of the logarithm of age and the logarithm of heart fatty acid-binding protein release(r = 0.737, P < .0001). This logarithm-logarithm plot showed a power function of age for heart fatty acid-binding protein release. The exponent and amplitude parameter of the power function was the aortic crossclamp time. Compared with children, infants had significantly more myocardial damage and worse clinical outcomes, and these factors were related to the aortic crossclamp time.

CONCLUSIONS

The younger the age of patients, the more vulnerable are their myocardia to injury caused by ischemia during definitive repair of congenital heart disease. Therefore, perioperative management for pediatric patients after cardiac surgery should be performed, taking into consideration the dependence of the myocardial damage on age and ischemic time.

Pediatric myocardial protection: a cardioplegic strategy is the "solution"

This article describes the experimental infrastructure and subsequent successful clinical application of a comprehensive cardioplegic strategy that limits intraoperative injury and improves postoperative outcomes in pediatric patients. The infant heart is at high risk of damage from poor protection as a result of preoperative hypertrophy, cyanosis, and ischemia. These factors may also make the immature (pediatric) heart more sensitive to cardioplegic arrest compared with the mature (adult) heart. The preoperative factors of cyanosis and pressure volume overload are discussed, followed by the infrastructure of the strategies of warm induction and reperfusion with substrate enhancements, multidose cardioplegia, and a "modified" integrated approach to allow ischemia only when visualization is needed in pediatric surgeries. The importance of using a blood cardioplegia solution, with reduced calcium, increased magnesium, and low perfusion pressure are also shown. A practical clinical framework based on these experimentally proven principles is then presented to allow the surgeon to apply these strategies clinically. The results of using these principles are depicted in a series of 567 patients, including 93 patients with hypoplastic left heart syndrome. Applications of these concepts should improve the safety of protection of the infant heart and reduce postoperative morbidity and mortality.

Effect of two different bypass techniques on the serum troponin-T levels in newborns and children: does pH-Stat provide better protection?

BACKGROUND

Cardiac troponin-T is a sensitive marker of myocardial damage. In a prospective study, the effect of 2 different pH strategies during cardiopulmonary bypass on ischemic myocardial injury and clinical outcome was measured in a pediatric population.

METHODS AND RESULTS

One hundred one patients (31 neonates 13.2+/-8.3 days and 70 children 34.5+/-44.1 months of age) undergoing open-heart surgery were selected to either alpha-stat (n=51) or pH-stat (n=50) acid-based management protocol. Serum troponin-T levels were measured before and 30 minutes after bypass and then 4 and 24 hours postoperatively. Surgical procedure, bypass details, inotropic support requirement, and postoperative recovery were recorded. Baseline troponin-T level was higher in neonates than in children (0.18+/-0.22 versus 0.04+/-0.05 microg/L, P=0.02). Also, a higher baseline level was found in patients with pulmonary hypertension (0.13+/-0.21 versus 0.04+/-0.05 microg/L, P=0.04). Cyanotic children showed a higher peak troponin-T level (3.76+/-3.11 versus 1.67+/-1.33 microg/L, P=0.04). Peak troponin levels showed a correlation with the length of circulatory arrest and aortic cross-clamp time. Postoperative levels remained high at 24 hours in patients requiring inotropic support. Peak troponin-T levels were significantly lower in the pH-stat group in patients with pulmonary hypertension (P=0.03) and in cases where circulatory arrest (P=0.01) or inotropic support (P=0.01) was necessary during operation than in those with alpha-stat technique. Postoperative ventilation time and length of intensive care unit stay were also significantly longer with alpha-stat than with pH-stat technique (P=0.005 and P=0.006, respectively).

CONCLUSIONS

Cardiac troponin-T sensitively reflects myocardial damage in children. Our results suggest that pH-stat acid-based management protocol may provide better protection against ischemic myocardial damage than alpha-stat technique.

Myocardial injury in children following resuscitation after cardiac arrest

BACKGROUND

Myocardial dysfunction occurs immediately after successful cardiac resuscitation. Our purpose was to determine whether measurement of cardiac troponin I in children with acute out-of-hospital cardiac arrest predicts the severity of myocardial injury.

METHODS AND RESULTS

This prospective, observational study was performed in the Pediatric Intensive Care Unit (PICU) on 24 patients following arrest, ranging in age from 8 months to 17 years. Troponin measurements were obtained on admission, and at 12, 24, and 48 h. Transthoracic echocardiograms were performed within 24 h after admission. Survival to hospital discharge was 29% (7/24). The mean age was 5.9+/-4.6 years for survivors and 4.2+/-5.3 years for non-survivors. The median (range) duration of cardiac arrest times for survivors was 6 min (3 to 63 min) versus 34 min (4 to 70 min) for nonsurvivors (P=0.02). Survivors received 1.3+/-2.2 doses of epinephrine (adrenaline) compared with 2.9+/-1.6 doses for non-survivors (P=0.02). Only one patient had ventricular fibrillation and defibrillation was unsuccessful. The ejection fraction for survivors averaged 73.2+/-11.2%, but for nonsurvivors only 55.4+/-19.8% (P=0.04). Ejection fraction correlated inversely with troponin at 12 h (r=-0.54, P=0.01) and at 24 h (r=-0.59, P=0.02). Circumferential fiber shortening for survivors was 37.5+/-7.8 and 25.5+/-10.7% for nonsurvivors (P=0.02). It also correlated inversely with troponin (r=-0.46, P=0.03 for survivors and r=-0.65, P=0.01, for nonsurvivors).

CONCLUSION

After cardiac arrest and resuscitation in pediatric patients, the severity of myocardial dysfunction was reflected in troponin I levels.

Usefulness of troponin I as a marker of myocardial injury after pediatric cardiac catheterization

Cardiac troponin I (cTnI) is a sensitive and specific marker of myocardial injury. The degree of myocardial injury associated with pediatric cardiac catheterization is unknown. We sought to investigate cTnI after pediatric cardiac catheterization, and to evaluate the degree of elevation observed with specific types of interventions. Seventy-three pediatric catheterizations were evaluated. Diagnostic procedures and interventions not expected to cause myocardial injury were assigned to group I, whereas interventional procedures expected to be associated with cardiac injury were assigned to group II. Group II procedures were further subdivided based on type of intervention. Serum samples were obtained before and after all procedures and analyzed for cTnI. Postprocedure cTnI levels were compared across groups and correlated with age and weight. Procedures in group II were associated with significantly higher cTnI levels than group I (median 2.65 ng/ml; interquartile range 0.9 to 4.9 ng/ml for group II vs 0.3; 0.3 to 1.6 ng/ml for group I, p <0.001). Within group II, cTnI was inversely correlated with age (p <0.05) and weight (p <0.05). Radiofrequency catheter ablation (RFA) caused higher cTnI levels than other types of interventions (median 3.7 ng/ml; 1.9 to 9.5 ng/ml for RFA vs 1.75; 0.7 to 4.9 ng/ml for non-RFA, p <0.05). Most pediatric interventional catheterization procedures are associated with myocardial injury, as evidenced by elevation of cTnI, with RFA causing higher levels than other interventions. Conversely, most diagnostic procedures are associated with no detectable myocardial injury. When compared with adult studies, pediatric patients seem to be at higher risk for myocardial injury from interventional cardiac catheterization.

Production of proinflammatory cytokines and myocardial dysfunction after arterial switch operation in neonates with transposition of the great arteries

OBJECTIVE

Neonates undergoing cardiac surgery have a systemic inflammatory reaction with release of proinflammatory cytokines, which could be responsible for myocardial dysfunction as a result of myocardial cell damage. The purpose of this study was to test the hypothesis that the production of proinflammatory cytokines during cardiac surgery would be associated with myocardial dysfunction after the arterial switch operation in neonates.

METHODS

A total of 63 neonates with transposition of the great arteries were operated on with combined deep hypothermic circulatory arrest and low-flow cardiopulmonary bypass at a median age of 7 days. Perioperative plasma concentrations of interleukins 6 and 8 were correlated with myocardial dysfunction, as assessed clinically and by echocardiography within 24 hours after the operation, and with perioperative cardiac troponin T blood levels as a marker of myocardial cell damage.

RESULTS

Myocardial dysfunction was observed in 11 patients (17.5%), and 2 of them died. Durations of cardiopulmonary bypass and aortic crossclamping, but not of circulatory arrest, were correlated with myocardial dysfunction. Patients with myocardial dysfunction had significantly higher cardiac troponin T blood levels at the end of cardiopulmonary bypass and 4 and 24 hours after the operation than did patients without myocardial dysfunction. Patients with myocardial dysfunction also had higher interleukin 6 plasma concentrations after cardiopulmonary bypass and 4 hours after the operation, as well as higher interleukin 8 plasma concentrations 4 and 24 hours after the operation, than did those without myocardial dysfunction. Postoperative interleukin 6 and 8 plasma concentrations were significantly correlated with postoperative cardiac troponin T blood levels. Multivariable analysis of independent risk factors for myocardial dysfunction comprising cytokine and troponin levels and bypass duration revealed interleukin 6 levels 4 hours after the operation as significant (P =.047).

CONCLUSIONS

Cardiac operations in neonates stimulate the production of proinflammatory cytokines, which may contribute to myocardial cell damage and myocardial dysfunction.

Pediatric cardiac postoperative care

The Heart Institute of the University of São Paulo, Medical School is a referral center for the treatment of congenital heart diseases of neonates and infants. In the recent years, the excellent surgical results obtained in our institution may be in part due to modern anesthetic care and to postoperative care based on well-structured protocols. The purpose of this article is to review unique aspects of neonate cardiovascular physiology, the impact of extracorporeal circulation on postoperative evolution, and the prescription for pharmacological support of acute cardiac dysfunction based on our cardiac unit protocols. The main causes of low cardiac output after surgical correction of heart congenital disease are reviewed, and methods of treatment and support are proposed as derived from the relevant literature and our protocols.

Usefulness of combining necrosis and platelet markers in triaging patients presenting with chest pain to the emergency department

BACKGROUND

Myocardial injury and platelet activation play important roles in the pathogenesis of unstable coronary syndromes. We sought to determine whether the combined measurement of platelet and necrosis markers would improve risk stratification, and yield higher diagnostic utility in patients presenting to the emergency department with chest pain.

METHODS AND RESULTS

Platelet and soluble P-selectin together with myoglobin, creatine kinase, CK-MB fraction, and troponin I were measured from the autologous samples in 122 consecutive patients. Statistical analysis revealed strong Spearman correlation coefficients (0.141--0.412; p<0.001) between platelet expression of P-selectin and plasma levels of necrosis markers. Platelet P-selectin and necrosis markers were independent predictors (c-index>0.7) for acute myocardial infarction, while plasma P-selectin exhibited random distribution. Elevated soluble P-selectin and myoglobin were the most valuable in identifying patients with congestive heart failure. None of the markers were useful for triaging chest pain patients with unstable angina. Analysis of incremental gains (Chi-squares) reveals that with respect to platelet P-selectin, myoglobin adds 50 % to AMI diagnostic value, and creatine kinase yields an additional 20 % in triaging these patients. The diagnostic value of soluble P-selectin is substantially (72 %) increased by myoglobin measurements, and enhanced even further (44 %) by adding cardiac troponin I for identifying heart failure patients among the chest pain population.

CONCLUSION

Simultaneous determination of platelet and necrosis markers improve the early diagnosis of acute myocardial infarction and congestive heart failure among patients with chest pain presenting into the Emergency Department. Well controlled clinical trials are needed to prove the advantage of combining platelet and necrosis data over presently used techniques in emergency medicine.

Pediatric myocardial protection: an overview

This article describes the experimental infrastructure and subsequent successful clinical application of a comprehensive bypass and cardioplegic strategy that limits intraoperative injury and improves postoperative outcomes in pediatric patients. The infant heart is at high risk of damage from poor protection because of preoperative hypertrophy, cyanosis, and ischemia. The background factors of vulnerability to damage caused by cyanosis and ischemia are discussed, together with studies of the infrastructure of strategies to use normoxia versus hyperoxia as bypass starts, white blood cell filtration, warm induction and reperfusion with substrate enhancements, multidose blood cardioplegia, and an integrated approach to allow ischemia only when vision is needed in pediatric surgeries. Data on cardioplegic management, including reducing calcium, increasing magnesium, and reducing perfusion pressure are shown, as used during this technique. These principles were applied to a consecutive series of 567 patients at the Heart Institute for Children and University of Illinois hospital over a 2-year period. Included also were 72 patients with hypoplastic left heart over a 4-year period with this myocardial management strategy. Application of these concepts may improve the safety of protection in infant hearts.

Myocardial injury in children with respiratory syncytial virus infection

OBJECTIVE

Respiratory syncytial virus (RSV) infection is associated with a number of extrapulmonary manifestations, including a sepsis-like syndrome characterized by any combination of hypothermia, fever, apnea, hypovolemia, and myocardial dysfunction. We hypothesized that RSV can have a direct injurious effect on the myocardium of infants and children that can be detected by the presence of cardiac troponin I (cTnI), a highly sensitive and specific marker of myocardial injury, in the blood of patients infected with the virus.

DESIGN

Serial cTnI measurements were obtained from patients admitted with documented RSV infection to the pediatric intensive care unit (PICU).

PARTICIPANTS

Data were collected and analyzed from 22 RSV infected patients and 11 control patients.

RESULTS

Elevated levels of cTnI were detected in 54.5% (12/22) of the study population during their PICU admission. The average cTnI level was significantly higher in the RSV infected group than in controls. There was a significant association between the presence of a positive troponin assay and the occurrence of a cardiovascular event, the need for inotropic support, and the requirement of mechanical ventilation. Patients who required inotropic support had a significantly higher cTnI level than the rest of the study population.

CONCLUSION

A large percentage of children admitted to the PICU with RSV infection have myocardial damage as detected by the use of commercially available troponin assays. Additionally, in a portion of these patients, this damage is clinically significant, leading to cardiovascular instability and the need for inotropic support.

Biochemical assessment of myocardial injury after cardiac surgery: effects of a platelet activating factor antagonist, bilateral internal thoracic artery grafts, and coronary endarterectomy

OBJECTIVE

Platelet activating factor antagonists reduce ischemia-reperfusion injury in experiments, but there is no supportive clinical evidence.

METHODS

A single-center, double-blind, minimized, placebo-controlled, randomized trial of low-dose (10 mg) or high-dose (100 mg) platelet activating factor antagonist was conducted in 150 patients undergoing coronary artery bypass grafting. Myocardial injury was determined by serial measurements of the MB isoenzyme of creatine kinase and cardiac troponin T. The effects of single or bilateral internal thoracic artery grafting and coronary endarterectomy on myocardial injury were also assessed.

RESULTS

The placebo and platelet activating factor antagonist groups were similar with respect to preoperative, intraoperative, and postoperative factors. Four patients (2.7%) died before discharge, 3 from cardiac events. Thirteen patients (9%) had biochemical evidence of myocardial infarction, of whom 3 died. Stepwise multiple regression analysis demonstrated that duration of cardiopulmonary bypass was the most important determinant of elevations in creatine kinase MB isoenzyme and cardiac troponin T up to 6 hours after the operation and that the use of a platelet activating factor antagonist and the number of internal thoracic artery grafts did not influence myocardial injury at any time. Endarterectomy was performed in 11 patients (7%), of whom 6 (55%) had biochemically defined myocardial infarction and of whom 1 died (9%). Endarterectomy was the most important determinant of elevated levels of creatine kinase MB isoenzyme and cardiac troponin T 24 and 48 hours after the operation.

CONCLUSION

Platelet activating factor antagonists do not reduce perioperative myocardial injury. Bilateral and single internal thoracic artery grafting results in similar levels of myocardial injury, whereas endarterectomy is frequently associated with biochemical evidence of myocardial injury.

Reducing postischemic reperfusion damage in neonates using a terminal warm substrate-enriched blood cardioplegic reperfusate

BACKGROUND

In adult cardiac operations, a warm cardioplegic reperfusate ("hot shot") before removing the aortic cross-clamp improves postbypass myocardial function and metabolic recovery. This modality, however, is rarely used in infants, despite the fact that postbypass cardiac dysfunction remains problematic, especially in cyanotic ("stressed") patients.

METHODS

To produce stress, 15 neonatal piglets underwent 60 minutes of ventilator hypoxia (fraction of inspired oxygen, 8% to 10%). All piglets then received similar protection with multidose cold blood cardioplegic solution during 70 minutes of arrest and were separated into three groups to examine the role of a warm reperfusate as well as possible augmentation by aspartate and glutamate enrichment. In 5 piglets (group 1), the cross-clamp was simply removed; in 5 (group 2), an unsupplemented warm blood cardioplegic reperfusate was given; and in 5 (group 3), the warm reperfusate was enriched with aspartate and glutamate. Myocardial function was assessed using pressure-volume loops and expressed as a percentage of control.

RESULTS

Compared with hearts receiving reperfusion with unmodified blood (group 1), a warm unsupplemented cardioplegic reperfusate (group 2) slightly improved systolic contractility (end-systolic elastance, 41% versus 50%; p < 0.05 versus group 1) and preload recruitable stroke work (41% versus 52%; p < 0.05 versus group 1), reduced diastolic stiffness (263% versus 245%; p < 0.05 versus group 1), and increased adenosine triphosphate (10.7 versus 11.9 microg/g tissue, p < 0.05 versus group 1). However, if aspartate and glutamate was included in the warm reperfusate (group 3), there was complete recovery of systolic function (end-systolic elastance, 105%+/-3%; p < 0.001 versus all groups) and preload recruitable stroke work (103%+/-2%; p < 0.001 versus all groups), a minimal rise in diastolic stiffness (154%+/-7%; p < 0.001 versus all groups), and preservation of adenosine triphosphate (15.5+/-0.5 microg/g; p < 0.001 versus all groups).

CONCLUSIONS

A warm cardioplegic reperfusate helps reduce the reperfusion injury, resulting in improved myocardial function and metabolic recovery in hypoxic (stressed) neonatal hearts, and this effect is maximized if the reperfusate is enriched with aspartate and glutamate, which completely preserves myocardial function.

Cardiac toxicity of intravenous terbutaline for the treatment of severe asthma in children: a prospective assessment

OBJECTIVE

To examine the cardiac toxicity as measured by elevations in serum cardiac troponin T (cTnT) and to compare creatine kinase (CK) and creatine kinase MB (CK-MB) and findings on electrocardiography (ECG) as markers of cardiac toxicity with cTnT during the infusion of intravenous terbutaline for the treatment of severe asthma in children.

STUDY DESIGN

Prospective cohort study of patients receiving intravenous terbutaline for severe asthma.

RESULTS

Only 3 (10%) of the 29 patients had elevations in cTnT. Each underwent mechanical ventilation for >72 hours, which was the earliest point at which cTnT elevations were identified. Eighteen (62%) patients had an elevation in CK, and 3 had an elevation in CK-MB fraction without an elevated cTnT. Twenty (69%) patients had ECG findings consistent with ischemia, and 19 of these patients had the ischemic findings on their preterbutaline ECG. Elevations in CK and CK-MB and ischemic changes on ECG did not correlate with elevations in cTnT. Both mechanical ventilation (P =.02) and prolonged administration (>72 hours) of intravenous terbutaline (P =. 02) were significantly associated with elevations in cTnT.

CONCLUSIONS

We found no clinically significant cardiac toxicity from the use of intravenous terbutaline for severe asthma as measured by serum cTnT elevations.

Ultra fast track in elective congenital cardiac surgery

BACKGROUND

Changes in healthcare delivery have affected the practice of congenital cardiac surgery. We recently developed a strategy of limited sternotomy, early extubation, and very early discharge, and reviewed the perioperative course of 198 pediatric patients undergoing elective cardiovascular surgical procedures, to assess the efficacy and safety of this approach.

METHODS

One hundred ninety-eight patients aged 0 to 18 years (median 3.2 years) underwent 201 elective cardiovascular surgical procedures over a 1-year period. All patients were admitted on the day of surgery. Patients were divided into six diagnostic groups: group 1, complex left-to-right shunts (n = 14, 7.0%); group 2, simple left-to-right shunts (n = 83, 41.3%); group 3, right-to-left shunts with pulmonary obstruction (n = 33, 16.4%); group 4, isolated, nonvalvular obstructive lesions (n = 30, 14.9%); group 5, isolated valvular anomalies (n = 20, 10.0%); and group 6, miscellaneous (n = 21, 10.4%).

RESULTS

After 201 procedures, 175 patients (87.1%) were extubated in the operating room and 188 (93.6%) within 4 hours from operation. Four patients (2.0%) were extubated more than 24 hours from completion of the procedure, and 2 (1.0%) died while on respiratory support (never weaned). Five patients (2.6%) failed early extubation (<4 hours). Early discharge was achieved for the vast majority of patients. Overall median length of stay (LOS, including day of surgery as day 1) was 2.0 days, with a median LOS of 3.0 days for those patients requiring circulatory arrest duration exceeding 20 minutes. Of 195 patients, 43 (24.6%), 121 (74.0%), and 159 (81.5%) were discharged, respectively, at <24, <48, <72 hours from admission. Longest and shortest mean postoperative LOS were in group 6 (9.9+/-14.5 days) and group 2 (1.6 = 0.7 days), respectively. Six patients (2.9%) died, and 11 (5.5%) suffered in-hospital complications. Thirty patients (15.4%) were either treated as outpatients (n = 11, 5.7%) or readmitted (n = 19, 9.7%) within 30 days from the time of surgery. Only 8 of 195 patients (4.1%) were readmitted with true surgical complications requiring invasive therapeutic procedures.

CONCLUSIONS

Selected patients with a broad spectrum of congenital heart disease may enjoy same-day admission, limited sternotomy, immediate extubation, and very early discharge with excellent outcomes and acceptable morbidity.

Acute right ventricular restrictive physiology after repair of tetralogy of Fallot: association with myocardial injury and oxidative stress

BACKGROUND

Acute right ventricular (RV) restrictive physiology after tetralogy of Fallot repair results in low cardiac output and a prolonged stay in the intensive care unit (ICU). However, its mechanism remains uncertain.

METHODS AND RESULTS

In the first 24 hours after tetralogy of Fallot repair (n=11 patients), serial prospective measurements were performed of cardiac troponin T, indexes of NO production (NO(2)(-) and NO(3)(-) combined as NOx), and iron metabolism and antioxidants. RV diastolic function was assessed by transthoracic Doppler echocardiography. Patients who had a long stay in the ICU were characterized by restrictive RV physiology (nonrestrictive group [n=7]: 3.0+/-0.6 days [mean+/-SD]; restrictive group [n=4]: 10.7+/-3.1 days). Troponin T peak concentration and the area under its concentration-time curve (AUC) were higher in the restrictive RV group (peak: restrictive group 17. 0+/-2.8 microg/L, nonrestrictive group 10.4+/-4.6 microg/L, P<0.03; AUC: restrictive group 268.8+/-73.6 microg. h(-1). L(-1), nonrestrictive group 136.2+/-48.3 microg. h(-1). L(-1), P<0.03). Plasma NOx/creatinine concentrations were higher in the restrictive group than the nonrestrictive group at 2 hours after bypass (restrictive group 1.3+/-0.4, nonrestrictive group 0.8+/-0.2; P=0. 04) but were similar by 24 hours. Iron loading peaked 2 to 10 hours after bypass and was more severe in the restrictive group (peak transferrin saturation: restrictive group 83.9+/-13.0%, nonrestrictive group 58.3+/-16.2%, P=0.05; minimum total iron-binding capacity: restrictive group 0.59+/-0.21%, nonrestrictive group 0.76+/-0.06%, P=0.04; minimum iron-binding antioxidant activity to oxyorganic radicals: restrictive group 9. 5+/-22.4%, nonrestrictive group 50.6+/-11.4%, P=0.01).

CONCLUSIONS

After tetralogy of Fallot repair, acute restrictive RV physiology is associated with greater intraoperative myocardial injury and postoperative oxidative stress with severe iron loading of transferrin.

Troponin-I for prediction of early postoperative course after pediatric cardiac surgery

OBJECTIVES

It was the aim of the study to test the prognostic value of cardiac troponin-I (cTnI) concerning the early postoperative course after pediatric cardiac surgery.

BACKGROUND

Cardiac troponin-I is a very specific and sensitive marker of myocardial damage in adults and children. As perioperative myocardial damage may be a significant factor of postoperative cardiac performance, serial cTnI values were analyzed in children undergoing open heart surgery.

METHODS

Seventy-three children undergoing elective correction of congenital heart disease including atrial and ventricular surgical manipulation were studied. Cardiac troponin-I levels were measured serially and correlated with intra- and postoperative parameters (such as doses and length of inotropic support, renal and hepatic function, duration of intubation). Patients with prolonged postoperative recovery were analyzed with special attention to the cTnI levels.

RESULTS

The cutoff point for the definition of a high and a low risk group of cTnI values was set at 25 microg/liter, 4 h after admission to the intensive care unit (ICU) and at 35 microg/liter considering the maximal value of cTnI in the first 24 h in the ICU. The results showed a highly significant correlation between the need for inotropic support, the severity of renal dysfunction and the duration of intubation in relation to the serum levels of cTnI.

CONCLUSIONS

Cardiac troponin-I serum levels after open heart surgery in children and infants 4 h after admission to the ICU allowed anticipation of the postoperative course and correlated with the incidence of significant postoperative complications.