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

Predictive Value of Myocardial Markers for Early Postoperative Mortality in Children with Congenital Heart Disease

To investigate the influencing factors of postoperative creatine kinase-MB (CK-MB) elevation in children with congenital heart disease and its peak value in predicting early postoperative mortality. The clinical data of 521 children with congenital heart disease under the age of 14 who underwent elective surgery in Beijing Children's Hospital from December 2018 to December 2020 were retrospectively analyzed. Stepwise multiple linear regression was used to analyze independent risk factors for postoperative CK-MB elevation, receiver operating characteristic (ROC) curve was used to determine the predictive value of postoperative CK-MB peak, CK peak, and LDH peak on mortality, and linear correlation and regression analysis were used to analyze the interdependence among postoperative CK-MB peak, CK peak, and LDH peak, and multivariate Logistic regression was used to identify independent risk factors for early postoperative mortality. Preterm birth (P = 0.004), ventriculotomy (P = 0.009), the re-establish of bypass (P = 0.007), cardiopulmonary bypass time (P = 0.024), deep hypothermic circulatory arrest time (P = 0.000), assisted ventilation time (P = 0.049), CK peak (P = 0.000), and LDH peak (P = 0.000) were independently associated with increased postoperative CK-MB elevation. The ROC curve showed that CK-MB peak had the strongest predictive value for death (AUC = 0.924), followed by LDH peak (AUC = 0.864) and CK peak (AUC = 0.758). The cut-off value of the postoperative CK-MB peak was 144.5 IU/L, with a sensitivity of 87% and a specificity of 97%. CK-MB peak was moderately correlated with CK peak (Pearson Correlation coefficient r = 0.514, P = 0.000) and strongly correlated with LDH peak (Pearson Correlation coefficient r = 0.601, P = 0.000). Multivariate analysis showed that delayed chest closure (OR = 4.865, P = 0.004) and postoperative CK-MB peak (OR = 1.031, P = 0.000) were independent risk factors for postoperative mortality. The postoperative CK-MB peak has a certain predictive value for the early postoperative mortality of children with congenital heart disease. It is affected by many factors, and the risk of mortality is significantly increased in children with severely elevated postoperative CK-MB.

Novel cfDNA Methylation Biomarkers Reveal Delayed Cardiac Cell Death after Open-heart Surgery

The use of cardiopulmonary bypass (CPB) is thought to cause delayed cardiac damage. DNA methylation-based liquid biopsies are novel biomarkers for monitoring acute cardiac cell death. We assessed cell-free DNA molecules as markers for cardiac damage after open-heart surgery. Novel cardiomyocyte-specific DNA methylation markers were applied to measure cardiac cfDNA in the plasma of 42 infants who underwent open-heart surgery. Cardiac cfDNA was elevated following surgery, reflecting direct surgery-related tissue damage, and declined thereafter in most patients. The concentration of cardiac cfDNA post-surgery correlated with the duration of CPB and aortic cross clamping. Strikingly, cardiac cfDNA at 6 h predicted duration of mechanical ventilation and maximal vasoactive-inotropic score better than did maximal troponin levels. Cardiac cfDNA reveals heart damage associated with CPB, and can be used to monitor cardiac cell death, to predict clinical outcome of surgery and to assess performance of cardioprotective interventions.

Are outcomes in congenital cardiac surgery better than ever?

BACKGROUND AND AIM OF THE STUDY

Congenital heart disease is the most common congenital defect among infants born in the United States. Within the first year of life, 1 in 4 of these infants will need surgery. Only one generation removed from an overall mortality of 14%, many changes have been introduced into the field. Have these changes measurably improved outcomes?

METHODS

The literature search was conducted through PubMed MEDLINE and Google Scholar from inception to October 31, 2021. Ultimately, 78 publications were chosen for inclusion.

RESULTS

The outcome of overall mortality has experienced continuous improvements in the modern era of the specialty despite the performance of more technically demanding surgeries on patients with complex comorbidities. This modality does not account for case-mix, however. In turn, clinical outcomes have not been consistent from center to center. Furthermore, variation in practice between institutions has also been documented. A recurring theme in the literature is a movement toward standardization and universalization. Examples include mortality risk-stratification that has allowed direct comparison of outcomes between programs and improved definitions of morbidities which provide an enhanced framework for diagnosis and management.

CONCLUSIONS

Overall mortality is now below 3%, which suggests that more patients are surviving their interventions than in any previous era in congenital cardiac surgery. Focus has transitioned from survival to improving the quality of life in the survivors by decreasing the incidence of morbidity and associated long-term effects. With the transformation toward standardization and interinstitutional collaboration, future advancements are expected.

Clinical and Laboratory Predictors for the Development of Low Cardiac Output Syndrome in Infants Undergoing Cardiopulmonary Bypass: A Pilot Study

Cardiac surgery employing cardiopulmonary bypass exposes infants to a high risk of morbidity and mortality. The objective of this study was to assess the utility of clinical and laboratory variables to predict the development of low cardiac output syndrome, a frequent complication following cardiac surgery in infants. We performed a prospective observational study in the pediatric cardiovascular ICU in an academic children’s hospital. Thirty-one patients with congenital heart disease were included. Serum levels of nucleosomes and a panel of 20 cytokines were measured at six time points in the perioperative period. Cardiopulmonary bypass patients were characterized by increased levels of interleukin-10, -6, and -1α upon admission to the ICU compared to non-bypass cardiac patients. Patients developing low cardiac output syndrome endured longer aortic cross-clamp time and required greater inotropic support at 12 h postoperatively compared to bypass patients not developing the condition. Higher preoperative interleukin-10 levels and 24 h postoperative interleukin-8 levels were associated with low cardiac output syndrome. Receiver operating characteristic curve analysis demonstrated a moderate capability of aortic cross-clamp duration to predict low cardiac output syndrome but not IL-8. In conclusion, low cardiac output syndrome was best predicted in our patient population by the surgical metric of aortic cross-clamp duration.

3D Modeling and Printing in Congenital Heart Surgery: Entering the Stage of Maturation

3D printing allows the most realistic perception of the surgical anatomy of congenital heart diseases without the requirement of physical devices such as a computer screen or virtual headset. It is useful for surgical decision making and simulation, hands-on surgical training (HOST) and cardiovascular morphology teaching. 3D-printed models allow easy understanding of surgical morphology and preoperative surgical simulation. The most common indications for its clinical use include complex forms of double outlet right ventricle and transposition of the great arteries, anomalous systemic and pulmonary venous connections, and heterotaxy. Its utility in congenital heart surgery is indisputable, although it is hard to "scientifically" prove the impact of its use in surgery because of many confounding factors that contribute to the surgical outcome. 3D-printed models are valuable resources for morphology teaching. Educational models can be produced for almost all different variations of congenital heart diseases, and replicated in any number. HOST using 3D-printed models enables efficient education of surgeons in-training. Implementation of the HOST courses in congenital heart surgical training programs is not an option but an absolute necessity. In conclusion, 3D printing is entering the stage of maturation in its use for congenital heart surgery. It is now time for imagers and surgeons to find how to effectively utilize 3D printing and how to improve the quality of the products for improved patient outcomes and impact of education and training.

Remote Ischemic Preconditioning has a Cardioprotective Effect in Children in the Early Postoperative Phase: A Meta-Analysis of Randomized Controlled Trials

In this updated meta-analysis, we assessed the cardioprotective effect of remote ischemic preconditioning (RIPC) in pediatric patients undergoing congenital heart surgery. A total of 9 randomized controlled trials (RCTs) involving 793 pediatric patients under 18 years old were identified. RIPC obviously reduced the release of troponin I at 6 h after surgery [standard mean difference (SMD) -0.59, 95% confidence interval (CI) -1.14 to -0.04; p = 0.03], mitigated the inotropic scores within 4-6 h (SMD -0.43, 95% CI -0.72 to -0.14; p = 0.004) and within 12 h (SMD -0.26, 95% CI -0.50 to -0.02; p = 0.03) and shortened the ventilator support time (SMD -0.28, 95% CI -0.49 to -0.07; p = 0.01) as well as the duration of intensive care unit (ICU) stay (SMD -0.21, 95% CI -0.35 to -0.06; p = 0.004). Our meta-analysis determined that RIPC had cardioprotective effects in the early postoperative phase. Additional RCTs focused on the cardiac benefits from RIPC in pediatric patients are warranted.

Does heart-type fatty acid-binding protein predict clinical outcomes after pediatric cardiac surgery?

Introduction:

The early identification of vulnerable pediatric cardiac surgery patients can help clinicians provide them with timely support. Heart-type fatty acid-binding protein. (H-FABP) is an early biomarker of myocardial injury in acute myocardial infarction in adults. In this study, we evaluated the correlations between postoperative H-FABP, creatine kinase-myocardial band (CK-MB), troponin-I, total bypass time, and clinical outcomes.

Methods:

In 32 pediatric patients that underwent ventricular septal defect. closure we measured H-FABP, troponin-I and CK-MB preoperatively and 1, 3, and 6 h after aortic declamping. Spearman's Rho correlations were calculated between laboratory and clinical parameters including inotropic support duration, aortic cross-clamp time, total bypass time, ventilation-weaning-time, and total Intensive Care Unit stay.

Results:

H-FABP, CK-MB, troponin-I, and total bypass time have a similarly weak to moderate correlation with clinical outcome measures.

Conclusions:

The predictive value of H-FABP for clinical outcome is not stronger than that of CK-MB, Troponin-I, or bypass times.

Does young age really put the heart at risk?

Despite significant advances in the management and treatment of heart disease in children, there continue to be patients who have worse outcomes than might be expected. A number of risk factors that could be responsible have been identified. Evidence-based findings will be reviewed, including whether young age and (or) reduced body weight exacerbate these responses. For example, newborn children undergoing congenital cardiac surgery are known to have worse outcomes than older children. Evidence exists that newborn hearts do not tolerate ischemia as well as adult hearts, developing irreversible injury sooner and exhibiting at-risk metabolic profiles. As well, in response to the administration of heparin, elevations in free fatty acids occur during congenital heart surgery in children, which can have detrimental effects on the heart. Furthermore, myocardial energetic state has also been suggested to impact outcomes. Unfavourable energetic profiles were correlated to lower body weights in the same age healthy newborn piglet model. Newborn children suffering from congenital heart disease, with lower body weights, also had lower myocardial energetic state and this correlated with longer postoperative ventilatory support as well as a trend to longer intensive care unit stay. These findings imply that unfavourable myocardial metabolic profiles could contribute to postoperative complications.

Heart-Type Fatty Acid Binding Protein and High-Dose Methylprednisolone in Pediatric Cardiac Surgery

OBJECTIVES

Corticosteroids possess cardioprotection in experimental cardiac ischemia/reperfusion. The authors hypothesized that if cardioprotection of corticosteroids occured during pediatric cardiac surgery, then methylprednisolone used in cardiopulmonary bypass prime would reduce postoperative concentrations of heart-type fatty-acid-binding protein, a cardiac biomarker.

DESIGN

A double-blind, placebo-controlled, randomized clinical trial.

SETTING

Operating room and pediatric intensive care unit of a university hospital.

PARTICIPANTS

Forty-five infants and young children undergoing ventricular or atrioventricular septal defect correction.

INTERVENTIONS

The patients received one of the following: 30 mg/kg of methylprednisolone intravenously after anesthesia induction (n = 15), 30 mg/kg of methylprednisolone in cardiopulmonary bypass prime solution (n = 15), or placebo (n = 15).

MEASUREMENTS AND MAIN RESULTS

Plasma heart-type fatty-acid-binding protein (hFABP) was measured. Preoperatively, hFABP did not differ among the study groups. Methylprednisolone administered preoperatively and in the cardiopulmonary bypass prime solution reduced hFABP by 44% (p = 0.010) and 38% (p = 0.033) 6 hours postoperatively. hFABP significantly correlated with concomitant troponin T after protamine administration (R = 0.811, p < 0.001) and 6 hours postoperatively (R = 0.806, p < 0.001).

CONCLUSIONS

Methylprednisolone in cardiopulmonary bypass prime solution administered only a few minutes before cardiac ischemia confered cardioprotection of the same magnitude as preoperative methylprednisolone as indicated by hFABP concentrations. Rapid cardioprotective actions of corticosteroids in pediatric heart surgery observed previously experimentally may have occurred.

Calcineurin signaling in the heart: The importance of time and place

The calcium-activated protein phosphatase, calcineurin, lies at the intersection of protein phosphorylation and calcium signaling cascades, where it provides an essential nodal point for coordination between these two fundamental modes of intracellular communication. In excitatory cells, such as neurons and cardiomyocytes, that experience rapid and frequent changes in cytoplasmic calcium, calcineurin protein levels are exceptionally high, suggesting that these cells require high levels of calcineurin activity. Yet, it is widely recognized that excessive activation of calcineurin in the heart contributes to pathological hypertrophic remodeling and the progression to failure. How does a calcium activated enzyme function in the calcium-rich environment of the continuously contracting heart without pathological consequences? This review will discuss the wide range of calcineurin substrates relevant to cardiovascular health and the mechanisms calcineurin uses to find and act on appropriate substrates in the appropriate location while potentially avoiding others. Fundamental differences in calcineurin signaling in neonatal verses adult cardiomyocytes will be addressed as well as the importance of maintaining heterogeneity in calcineurin activity across the myocardium. Finally, we will discuss how circadian oscillations in calcineurin activity may facilitate integration with other essential but conflicting processes, allowing a healthy heart to reap the benefits of calcineurin signaling while avoiding the detrimental consequences of sustained calcineurin activity that can culminate in heart failure.

Myocardial Injury in Children with Unoperated Congenital Heart Diseases

Background. Children with congenital heart diseases (CHDs) may have a risk of developing myocardial injury caused by volume and pressure overload. Objective. To evaluate the incidence of myocardial injury in children with cyanotic and acyanotic CHDs using cTnI assay and to correlate it with different hemodynamic parameters. Methods. This study included 80 children with CHDs (40 acyanotic and 40 cyanotic) as well as 40 healthy children (control group). Serum cTnI levels were measured for patients and control. Pulmonary to systemic blood flow (Qp/Qs) and pulmonary to systemic arterial pressure (Pp/Ps) ratios were measured for children with CHDs during cardiac catheterization. Results. Sixty-four out of 80 patients with CHDs had myocardial injury as evidenced by increased cTnI. Serum cTnI was significantly higher in both cyanotic and acyanotic groups compared to control group (p < 0.05). Serum cTnI level significantly correlated with oxygen saturation (SpO₂), ejection fraction (EF), Qp/Qs, and Pp/Ps ratios. Conclusion. The incidence of myocardial injury was high in children with CHDs. The use of cTnI for follow-up of children with CHDs may help early detection of myocardial injury and help early management of these cases.

Cellular redox status determines sensitivity to BNIP3-mediated cell death in cardiac myocytes

The atypical BH3-only protein Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is an important regulator of hypoxia-mediated cell death. Interestingly, the susceptibility to BNIP3-mediated cell death differs between cells. In this study we examined whether there are mechanistic differences in BNIP3-mediated cell death between neonatal and adult cardiac myocytes. We discovered that BNIP3 is a potent inducer of cell death in neonatal myocytes, whereas adult myocytes are remarkably resistant to BNIP3. When exploring the potential underlying basis for the resistance, we discovered that adult myocytes express significantly higher levels of the mitochondrial antioxidant manganese superoxide dismutase (MnSOD) than neonatal myocytes. Overexpression of MnSOD confers resistance to BNIP3-mediated cell death in neonatal myocytes. In contrast, the presence of a pharmacological MnSOD inhibitor, 2-methoxyestradiol, results in increased sensitivity to BNIP3-mediated cell death in adult myocytes. Cotreatment with the mitochondria-targeted antioxidant MitoTEMPO or the MnSOD mimetic manganese (III) tetrakis (4-benzoic acid) porphyrin chloride abrogates the increased cell death by 2-methoxyestradiol. Moreover, increased oxidative stress also restores the ability of BNIP3 to induce cell death in adult myocytes. Taken together, these data indicate that redox status determines cell susceptibility to BNIP3-mediated cell death. These findings are clinically relevant, given that pediatric hearts are known to be more vulnerable than the adult heart to ischemic injury. Our studies provide important insight into why pediatric hearts are more sensitive to ischemic injury and may help in the clinical management of childhood heart disease.

Dysregulation of catalase activity in newborn myocytes during hypoxia is mediated by c-Abl tyrosine kinase

In the adult heart, catalase (CAT) activity increases appropriately with increasing levels of hydrogen peroxide, conferring cardioprotection. This mechanism is absent in the newborn for unknown reasons. In the present study, we examined how the posttranslational modification of CAT contributes to its activation during hypoxia/ischemia and the role of c-Abl tyrosine kinase in this process. Hypoxia studies were carried out using primary cardiomyocytes from adult (>8 weeks) and newborn rats. Following hypoxia, the ratio of phosphorylated to total CAT and c-Abl in isolated newborn rat myocytes did not increase and were significantly lower (1.3- and 4.2-fold, respectively; P < .05) than their adult counterparts. Similarly, there was a significant association (P < .0005) between c-Abl and CAT in adult cells following hypoxia (30.9 ± 8.2 to 70.7 ± 13.1 au) that was absent in newborn myocytes. Although ubiquitination of CAT was higher in newborns compared to adults following hypoxia, inhibition of this did not improve CAT activity. When a c-Abl activator (5-(1,3-diaryl-1H-pyrazol-4-yl)hydantoin [DPH], 200 µmol/L) was administered prior to hypoxia, not only CAT activity was significantly increased (P < .05) but also phosphorylation levels were also significantly improved (P < .01) in these newborn myocytes. Additionally, ischemia-reperfusion (IR) studies were performed using newborn (4-5 days) rabbit hearts perfused in a Langendorff method. The DPH given as an intracardiac injection into the right ventricle of newborn rabbit resulted in a significant improvement (P < .002) in the recovery of developed pressure after IR, a key indicator of cardiac function (from 74.6% ± 6.6% to 118.7% ± 10.9%). In addition, CAT activity was increased 3.92-fold (P < .02) in the same DPH-treated hearts. Addition of DPH to adult rabbits in contrast had no significant effect (from 71.3% ± 10.7% to 59.4% ± 12.1%). Therefore, in the newborn, decreased phosphorylation of CAT by c-Abl potentially mediates IR-induced dysfunction, and activation of c-Abl may be a strategy to prevent ischemic injury associated with surgical procedures.

Is routine rapid-staged bilateral pulmonary artery banding before stage 1 Norwood a viable strategy?

OBJECTIVE

We adopted a policy of rapid-staged bilateral pulmonary artery banding (bPAB) before the Norwood (NW) procedure for all patients with hypoplastic left heart syndrome. We hypothesized that this strategy might mitigate some of the traditional risk factors and that postponing a major bypass procedure beyond the newborn period could have both short- and long-term benefits. The purpose of the present study was to evaluate the efficacy of this strategy with respect to the short-term outcomes.

METHODS

From 2008 to 2010, 14 patients underwent bPAB and maintenance of ductal patency with prostaglandin E1 infusion before stage 1 NW. For reference, we also reviewed the data from patients who had undergone the primary NW procedure in the 2 years immediately before the study period.

RESULTS

The bPAB was performed at a median age of 6 days (range, 2-39), gestational age of 38.5 weeks (range, 36-41), and weight of 2.75 kg (range, 2.3-3.6). The subsequent NW was performed at a gestational age of 43.5 weeks (range, 41-51) and weight of 3.2 kg (range, 2.2-4.9). When the NW procedure was eventually performed on the pBAB group, the maximum blood lactate levels within the first 24 hours after the NW were lower than those in the earlier primary NW group (2.8±0.9 vs 10.1±6.5 mmol/dL, P=.0002) and the urine output in the first 24 hours after the NW was greater in the pPAB group (4.1±2.1 vs 2.2±1.5 mL/kg/h; P=.0051).

CONCLUSIONS

These data suggest that rapid-staged bPAB before NW can reduce the challenge of postoperative management in the early postoperative period after the NW procedure and have potential to improve the outcomes.

Cardioprotection from oxidative stress in the newborn heart by activation of PPARγ is mediated by catalase

Regulation of catalase (CAT) by peroxisome proliferator-activated receptor-γ (PPARγ) was investigated to determine if PPARγ activation provides cardioprotection from oxidative stress caused by hydrogen peroxide (H(2)O(2)) in an age-dependent manner. Left ventricular developed pressure (LVDP) was measured in Langendorff perfused newborn or adult rabbit hearts, exposed to 200μM H(2)O(2), with perfusion of rosiglitazone (RGZ) or pioglitazone (PGZ), PPARγ agonists. We found: (1) H(2)O(2) significantly decreased sarcomere shortening in newborn ventricular cells but not in adult cells. Lactate dehydrogenase (LDH) release occurred earlier in newborn than in adult heart, which may be due, in part, to the lower expression of CAT in newborn heart. (2) RGZ increased CAT mRNA and protein as well as activity in newborn but not in adult heart. GW9662 (PPARγ blocker) eliminated the increased CAT mRNA by RGZ. (3) In newborn heart, RGZ and PGZ treatment inhibited release of LDH in response to H(2)O(2) compared to H(2)O(2) alone. GW9662 decreased this inhibition. (4) LVDP was significantly higher in both RGZ+H(2)O(2) and PGZ+H(2)O(2) groups than in the H(2)O(2) group. Block of PPARγ abolished this effect. In contrast, there was no effect of RGZ in adult. (5) The cardioprotective effects of RGZ were abolished by inhibition of CAT. In conclusion, PPARγ activation is cardioprotective to H(2)O(2)-induced stress in the newborn heart by upregulation of catalase. These data suggest that PPARγ activation may be an effective therapy for the young cardiac patient.

Significance of hemolysis on extracorporeal life support after cardiac surgery in children

Hemolysis is common during extracorporeal life support (ECLS). Elevated levels of circulating plasma free hemoglobin (FHb) has been linked to the development of hemoglobinuria nephropathy. Its clinical significance in patients receiving ECLS remains unknown. Medical records of 104 children <3 years old who required ECLS after repair of congenital heart disease were reviewed. Forty-two patients required continuous renal replacement therapy (CRRT) during ECLS (CRRT group), and 62 patients did not (no-CRRT group). For all patients, FHb level and the degree of fluid overload at the end of ECLS predicted the mortality rate during ECLS. Compared with the no-CRRT group, the CRRT group had a higher mortality rate during ECLS, a higher peak FHb level during ECLS, a higher FHb level at the end of ECLS, and more days of ECLS. In the CRRT group, the FHb level at the end of ECLS predicted death during ECLS. In the no-CRRT group, the peak FHb level was associated with a worse renal function. In conclusion, elevated FHb levels were associated with renal dysfunction and death during ECLS in children undergoing cardiac surgery. Further studies are needed to elucidate the cause-effect relationship in our findings.

Surgical management of multiple ventricular septal defects: the role of the felt sandwich technique

OBJECTIVE

Recently, the felt sandwich technique has been widely used to close muscular ventricular septal defects. We evaluated the early and midterm results of our strategy (a combination of the sandwich technique and direct closures) and assessed the role of the sandwich technique in the treatment of multiple ventricular septal defects.

METHODS

Twenty-nine consecutive patients underwent an operation for multiple ventricular septal defects and associated cardiac malformations. They included 17 boys and 12 girls with a median age of 6.0 months. Thirteen patients had 4 or more ventricular septal defects (Swiss cheese septum).

RESULTS

There was no surgical or follow-up mortality, and no reoperations were required. There were no cases of heart block and no significant residual shunts in the latest follow-up study. Two patients with Swiss cheese septum had postoperative congestive heart failure. Three muscular ventricular septal defects were closed with the sandwich technique in these 2 patients, whereas 1 or fewer ventricular septal defects were closed with the sandwich technique in the other 27 patients. Seven (77.8%) of 9 patients who underwent the sandwich procedure had septal dysfunction, whereas 5 (25.0%) of the other 20 patients showed septal dysfunction (P < .05).

CONCLUSIONS

The outcome of the surgical repair of multiple ventricular septal defects was satisfactory. Although the sandwich technique is simple and effective, the use of numerous felt patches disturbed the movement of the interventricular septum. An effort should be made to close the muscular ventricular septal defect directly to avoid postoperative cardiac dysfunction. Large apical ventricular septal defects, especially those located just underneath the moderator band, are considered suitable for the sandwich technique.

Risk stratification in neonates and infants submitted to cardiac surgery with cardiopulmonary bypass: a multimarker approach combining inflammatory mediators, N-terminal pro-B-type natriuretic peptide and troponin I

Low cardiac output syndrome (LCOS) is a common problem following cardiac surgery with cardiopulmonary bypass (CPB) in neonates and infants, and its early recognition remains a challenging task. We aimed to test whether a multimarker approach combining inflammatory and cardiac markers provides complementary information for prediction of LCOS and death in children submitted to cardiac surgery with CPB. Forty-six children younger than 18 months with congenital heart defects were prospectively enrolled. No intervention was made. Blood samples were collected pre-operatively, during CPB and post-operatively (PO) for measurement of interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor (TNF)-alpha, cardiac troponin I (cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Clinical data and outcome variables were recorded. Logistic regression was used to identify predictors of LCOS and death. Multivariate logistic regression identified pre-operative NT-proBNP and IL-8 4h PO as independent predictors of LCOS, while cTnI 4h PO and CPB length were independent predictors of death. The use of inflammatory and cardiac markers in combination improved sensitivity, negative predictive value and accuracy of the models. In conclusion, the combined assessment of inflammatory and cardiac biochemical markers can be useful for identifying young children at increased risk for LCOS and death after heart surgery with CPB.

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.

Myocardial protection using an omega-3 fatty acid infusion: Quantification and mechanism of action

OBJECTIVES

Omega-3 fatty acids exhibit anti-inflammatory, antithrombotic, and antiarrhythmic properties. We investigated the extent and underlying mechanism of protection conferred by a pre-emptive omega-3 infusion in a model of regional cardiac ischemia-reperfusion injury.

METHODS

New-Zealand White rabbits received either the omega-3 infusion or a control infusion of 0.9% saline (n = 14 in each group). The large marginal branch of the left coronary artery was occluded for 30 minutes, cardiac function was assessed during 3 hours of reperfusion, and infarct size was measured. Pretreatment-induced alterations in myocardial membrane fatty acid composition and intramyocardial heat shock protein 72 were additionally assessed (n = 5 in each group). Serum markers of myocardial membrane oxidative stress, malonaldehyde and 8-isoprostane, were also determined. Results are expressed as means +/- standard error of the mean and significance was tested with analysis of variance.

RESULTS

Pretreatment increased myocardial membrane omega-3 fatty acid content 5-fold, from 0.94% +/- 0.07% in controls to 5.38% +/- 0.44% in the omega-3 group (P < .01), and it produced a 225% elevation of levels of heat shock protein 72 (P = .019) before ischemia-reperfusion. This was associated with a 40% reduction in infarct size (P < .01). Whereas the reperfusion-induced rise in malonaldehyde levels was higher with omega-3 pretreatment, 10.2 +/-1.5 micromol/L versus 6.1 +/- 0.7 micromol/L in controls (P = .04), 8-isoprostanes showed a 9-fold reduction, 679 +/- 190 pg/mL in controls vs 74 +/- 45 pg/mL in the omega-3 group (P = .0077).

CONCLUSIONS

A pre-emptive omega-3 infusion significantly reduces infarct size through the dual mechanisms of upregulation of heat shock protein 72, a key preconditioning protein, and a dramatic increase in the omega-3 content of myocardial membranes, which appears to facilitate a shift in oxidant ischemia-reperfusion injury. Further study to optimally shorten the pretreatment regimen for this potentially acceptable infusion will now be pursued.

Single-ventricle palliation for high-risk neonates: the emergence of an alternative hybrid stage I strategy

BACKGROUND

Survival after stage I palliation for hypoplastic left heart syndrome or related anomalies remains poor in high-risk neonates. We hypothesized that a less invasive hybrid approach would be beneficial in this patient population.

METHODS

The hybrid stage I procedure was performed in the catheterization laboratory. Via a median sternotomy, both branch pulmonary arteries were banded, and a ductal stent was delivered via a main pulmonary artery puncture and positioned under fluoroscopic guidance.

RESULTS

Between October 2003 and June 2005, 14 high-risk neonates underwent a hybrid stage I procedure. Eleven of 14 had hypoplastic left heart syndrome. Two also underwent peratrial atrial septal stenting, and 5 required percutaneous atrial stenting later. Two neonates with an intact or highly restrictive atrial septum had emergency percutaneous atrial stent placement. Hospital survival was 11 (78.5%) of 14. One patient required extracorporeal membrane oxygenation support for intraoperative cardiac arrest. He underwent cardiac transplantation but died later of sepsis. One patient died of ductal stent embolization, and a third died of progressive cardiac dysfunction. The first 4 patients required pulmonary artery band revisions. There were none after we modified our technique and added branch pulmonary artery angiograms. There were 2 interstage deaths from atrial stent occlusion and from preductal retrograde coarctation. Eight patients underwent stage II procedures, consisting of aortic arch reconstruction, atrial septectomy, and cavopulmonary shunt. Two patients died after stage II. One patient is awaiting stage II.

CONCLUSIONS

The hybrid stage I palliation is a valid option in high-risk neonates. As experience is accrued, it may become the preferred alternative. However, in aortic atresia, the development of preductal retrograde coarctation is a significant problem.

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.