Cardiac surgery with deep hypothermic circulatory arrest produces less systemic inflammatory response than low-flow cardiopulmonary bypass in newborns

Early outcomes of experience warm surgery in children undergoing complete repair of tetralogy of Fallot in developing countries

OBJECTIVES

While significant evidence supports the benefits of normothermic cardiopulmonary bypass (NCPB) over hypothermic techniques, many institutions in developing countries, including ours, continue to employ hypothermic methods. This study aimed to assess the early postoperative outcomes of normothermic cardiopulmonary bypass (NCPB) for complete surgical repair via the Tetralogy of Fallot (TOF) within our national context.

METHODS

We conducted this study in the Pediatric Cardiac Intensive Care Unit (PCICU) at the University Children's Hospital. One hundred patients who underwent complete TOF repair were enrolled and categorized into two groups: the normothermic group (n = 50, temperature 35-37 °C) and the moderate hypothermic group (n = 50, temperature 28-32 °C). We evaluated mortality, morbidity, and postoperative complications in the PCICU as outcome measures.

RESULTS

The demographic characteristics were similar between the two groups. However, the cardiopulmonary bypass (CPB) time and aortic cross-clamp (ACC) time were notably longer in the hypothermic group. The study recorded seven deaths, yielding an overall mortality rate of 7%. No significant differences were observed between the two groups concerning mortality, morbidity, or postoperative complications in the PCICU.

CONCLUSIONS

Our findings suggest that normothermic procedures, while not demonstrably effective, are safe for pediatric cardiac surgery. Further research is warranted to substantiate and endorse the adoption of this technique.

Normothermic Versus Hypothermic Norwood Procedure

BACKGROUND

Either deep hypothermia with circulatory arrest or hypothermic perfusion with antegrade selective cerebral perfusion is used during the Norwood procedure for hypoplastic left heart syndrome. Normothermic perfusion has been described for pediatric patients. The aim of this study was to compare the early outcomes of patients undergoing the Norwood procedure with antegrade selective cerebral perfusion under hypothermia with the procedure under normothermia.

METHODS

From 2005 to 2020, 117 consecutive patients with hypoplastic left heart syndrome underwent the Norwood procedure: 68 (58.2%) under hypothermia and 49 (41.8%) under normothermia. Antegrade selective cerebral perfusion flow was adjusted to maintain right radial arterial pressure above 50 mm Hg, and a flow rate of 40 to 50 mL kg^-1 min^-1. Baseline characteristics, operative data, and postoperative outcomes including lactate recovery time were compared.

RESULTS

The baseline characteristics and cardiovascular diagnosis were similar in both groups. The normothermic group had a significantly shorter bypass time (in minutes) of 90.31 (±31.60) versus 123.63 (±25.33), a cross-clamp time of 45.24 (±16.35) versus 81.93 (±16.34), and an antegrade selective cerebral perfusion time of 25.61 (±13.84) versus 47.30 (±14.35) (P < .001). There were no statistically significant differences in the immediate postoperative course, or in terms of in-hospital mortality, which totaled 9 (18.4%) in the normothermic group, and 10 (14.9%) in the hypothermic group (P = .81).

CONCLUSION

The normothermic Norwood procedure with selective cerebral perfusion is feasible and safe in terms of in-hospital mortality and short-term outcomes. It is comparable to the standard hypothermic Norwood with selective cerebral perfusion.

Cooling to Hypothermic Circulatory Arrest by Immersion vs. Cardiopulmonary Bypass (CPB): Worse Outcome After Rewarming in Immersion Cooled Pigs

Introduction

Cooling by cardiopulmonary bypass (CPB) to deep hypothermic cardiac arrest (HCA) for cardiac surgical interventions, followed by CPB-rewarming is performed on a routine basis with relatively low mortality. In contrast, victims of deep accidental hypothermia rewarmed with CPB generally have a much worse prognosis. Thus, we have developed an intact pig model to compare effects on perfusion pressures and global oxygen delivery (DO₂) during immersion cooling versus cooling by CPB. Further, we compared the effects of CPB-rewarming between groups, to restitute cardiovascular function, brain blood flow, and brain metabolism.

Materials and Methods

Total sixteen healthy, anesthetized juvenile (2–3 months) castrated male pigs were randomized in a prospective, open placebo-controlled experimental study to immersion cooling (IMM_c, n = 8), or cooling by CPB (CPB_c, n = 8). After 75 minutes of deep HCA in both groups, pigs were rewarmed by CPB. After weaning from CPB surviving animals were observed for 2 h before euthanasia.

Results

Survival rates at 2 h after completed rewarming were 4 out of 8 in the IMM_c group, and 8 out of 8 in the CPB_c group. Compared with the CPB_c-group, IMM_c animals showed significant reduction in DO₂, mean arterial pressure (MAP), cerebral perfusion pressure, and blood flow during cooling below 25°C as well as after weaning from CPB after rewarming. After rewarming, brain blood flow returned to control in CPB_c animals only, and brain micro dialysate-data showed a significantly increase in the lactate/pyruvate ratio in IMM_c vs. CPB_c animals.

Conclusion

Our data indicate that, although global O₂ consumption was independent of DO₂, regional ischemic damage may have taken place during cooling in the brain of IMM_c animals below 25°C. The need for prolonged extracorporeal membrane oxygenation (ECMO) should be considered in all victims of accidental hypothermic arrest that cannot be weaned from CPB immediately after rewarming.

Profiles and Predictive Values of Interleukin-6 in Aortic Dissection: a Review

Aortic dissection (AD) has been recognized to be associated with an inflammatory process. Clinical observations demonstrated that patients with AD had an elevated interleukin (IL)-6 level in comparison to hypertensive or healthy controls. Adverse events such as acute lung injury, postimplantation syndrome, and death are associated with an elevated IL-6 level. Thus, circulating IL-6 could be a reliable biomarker for the diagnosis of AD and for the eveluation of the therapeutic outcomes and the prognosis of AD patients. Therapeutic interventions aiming at attenuating the inflammatory status by IL-6 neutralization could effectively decrease the IL-6 level and thus reverse the progression of the disorder of AD patient. Endovascular aortic repair can effectively control the inflammatory cytokines. Selective antegrade cerebral perfusion with deep hypothermic circulatory arrest during aortic arch replacement shows better neuroprotectve effect with an improved IL-6 level of the cerebrospinal fluid. These results facilitate the understanding of the etiology of AD and guide the directions for the treatment of acute AD in the future. More effective therapeutic agents developed based on the theories of IL-6 signaling involved in the mechasims of AD are anticipated.

Sera From Children After Cardiopulmonary Bypass Reduces Permeability of Capillary Endothelial Cell Barriers

OBJECTIVES

Children undergoing cardiopulmonary bypass develop clinically impactful capillary leak of unclear etiology. A widely held hypothesis that exposure of circulating cells to the cardiopulmonary bypass circuit induces the release of inflammatory mediators that act to disrupt intercellular junctions of capillary endothelial cells inducing paracellular capillary leak either directly or through new gene expression.

DESIGN

Cohort study.

SETTING

Tertiary pediatric hospital.

PATIENTS

Twenty children undergoing surgery with cardiopulmonary bypass for congenital heart disease. Serum was collected before cardiopulmonary bypass, 2 hours after cardiopulmonary bypass, and 18 hours after cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We analyzed the effects of 10% patient sera on the "function, structure, and gene expression" of cultured human dermal and pulmonary microvascular endothelial cells. Changes in barrier "function" were measured using transendothelial electrical resistance. Associations between changes in transendothelial electrical resistance and subject characteristics were analyzed using linear mixed effects model with area under the resistance curve as outcome. Changes in junctional "structure" were assessed by analyzing the organization of the endothelial cell junctional proteins claudin-5 and VE-cadherin using immunofluorescence microscopy. Changes in inflammatory "gene expression" were measured using real-time quantitative reverse transcription-polymerase chain reaction. All serum samples induced a transient, 120-minute increase in transendothelial electrical resistance followed by persistent loss of barrier function. Unexpectedly, sera collected postcardiopulmonary bypass-induced significantly less loss of barrier function in both dermal and pulmonary capillary endothelial cell compared with precardiopulmonary bypass sera. Consistent with the transendothelial electrical resistance results, claudin-5 and vascular endothelial-cadherin junctional staining showed less disruption in cultures treated with postcardiopulmonary bypass sera. Expression of genes commonly associated with inflammation was largely unaffected by patient sera.

CONCLUSIONS

Contrary to the hypothesis, sera taken from children after cardiopulmonary bypass induces less capillary barrier disruption relative to sera taken from children before cardiopulmonary bypass, and none of the sera induced significant changes in expression of inflammatory genes.

Varying Evidence on Deep Hypothermic Circulatory Arrest in Thoracic Aortic Aneurysm Surgery

Cardiovascular surgeons have long debated the safe duration of deep hypothermic circulatory arrest during thoracic aortic aneurysm surgery. The rationale for using adjunctive cerebral perfusion (or not) is to achieve the best technical aortic repair with the lowest risk of morbidity and death. In this literature review, we highlight the debates surrounding these issues, evaluate the disparate findings on deep hypothermic circulatory arrest durations and temperatures, and consider the usefulness of adjunctive perfusion.

Blood Versus Crystalloid Cardioplegia in Pediatric Cardiac Surgery: A Systematic Review and Meta-analysis

The benefit of blood cardioplegia (BCP) compared to crystalloid cardioplegia (CCP) is still debatable. Our aim was to systematically review and synthesize all available evidence on the use of BCP and CCP to assess if any modality provides superior outcomes in pediatric cardiac surgery. A systematic literature search of the PubMed and Cochrane databases was performed with respect to the PRISMA statement (end-of-search date: January 30th, 2017). We extracted data on study design, demographics, cardioplegia regimens, and perioperative outcomes as well as relevant biochemical markers, namely cardiac troponin I (cTnI), lactate, and ATP levels at baseline, after reperfusion and postoperatively at 1, 4, 12, and 24 h as applicable. Data were appropriately pooled using random and mixed effects models. Our systematic review includes 56 studies reporting on a total of 7711 pediatric patients. A meta-analysis of the 10 eligible studies directly comparing BCP (n = 416) to CCP (n = 281) was also performed. There was no significant difference between the two groups with regard to cTnI and Lac at any measured time point, ATP levels after reperfusion, length of intensive care unit stay (WMD: -0.08, 95% CI -1.52 to 1.36), length of hospital stay (WMD: 0.13, 95% CI -0.85 to 1.12), and 30-day mortality (OR 1.11, 95% CI 0.43-2.88). Only cTnI levels at 4 h postoperatively were significantly lower with BCP (WMD: -1.62, 95% CI -2.07 to -1.18). Based on the available data, neither cardioplegia modality seems to be superior in terms of clinical outcomes, ischemia severity, and overall functional recovery.

Microvascular fluid exchange during CPB with deep hypothermia circulatory arrest or low flow

OBJECTIVE

Use of deep hypothermic low-flow (DHLF) cardiopulmonary bypass (CPB) has been associated with higher fluid loading than the use of deep hypothermia circulatory arrest (DHCA). We evaluated whether these perfusion strategies influenced fluid extravasation rates and edema generation differently per-operatively.

MATERIALS AND METHODS

Twelve anesthetized pigs, randomly allocated to DHLF (n = 6) or DHCA (n = 6), underwent 2.5 hours CPB with cooling to 20°C for 30 minutes (min), followed by 30 min arrested circulation (DHCA) or 30 min low-flow circulation (DHLF) before 90 min rewarming to normothermia. Perfusion of tissues, fluid requirements, plasma volumes, colloid osmotic pressures and total tissue water contents were recorded and fluid extravasation rates calculated. During the experiments, cerebral microdialysis was performed in both groups.

RESULTS

Microvascular fluid homeostasis was similar in both groups, with no between-group differences, reflected by similar fluid extravasation rates, plasma colloid osmotic pressures and total tissue water contents. Although extravasation rates increased dramatically from 0.10 (0.11) ml/kg/min (mean with standard deviation in parentheses) and 0.16 (0.02) ml/kg/min to 1.28 (0.58) ml/kg/min and 1.06 (0.41) ml/kg/min (DHCA and DHLF, respectively) after the initiation of CPB, fluid filtrations during both cardiac arrest and low flow were modest and close to baseline values. Cerebral microdialysis indicated anaerobic metabolism and ischemic brain injury in the DHCA group.

CONCLUSION

No differences in microvascular fluid exchange could be demonstrated as a direct effect of DHCA compared with DHLF. Thirty minutes of DHCA was associated with anaerobic cerebral metabolism and possible brain injury.

Evaluating the Quality of Trials of Hypothermic Circulatory Arrest Aortic Surgery

The quality of level 1 evidence in reports on deep hypothermic circulatory arrest was assessed, and the confounding factors in surgical management and study design that can prevent meta-analysis formulation were determined. A systematic search of the literature was conducted using categorized nomenclature for randomized controlled trials in adult patients undergoing deep hypothermic circulatory arrest in the last 40 years. Twelve randomized controlled trials (2.3%) were found among 504 publications on deep hypothermic circulatory arrest listed on Medline from 1960; only 4 of them related to adults. One adequately powered study demonstrated reduced blood loss in deep hypothermic circulatory arrest using aprotinin. Three studies comparing retrograde and antegrade perfusion were underpowered. The median CONSORT score was 14 (range, 13–15). There were no consistent measures of similar outcomes (neuropsychometric, neurocognitive). No explanation was provided for the difference in reported ranges of neurological deficits in nonrandomized (5%–70%) and randomized (3%–9%) studies. Existing studies of deep hypothermic circulatory arrest are insufficient and inconsistent in the outcome measured, which explains the lack of a meta-analysis. Neurological injury remains high, and an appropriately powered study of interventions that can optimize cerebral perfusion is necessary.

Factors affecting Fontan length of stay: Results from the Single Ventricle Reconstruction trial

BACKGROUND

In the Single Ventricle Reconstruction trial, infants with hypoplastic left heart syndrome (HLHS) who received a right-ventricle-to-pulmonary-artery shunt (RVPAS) versus a modified Blalock-Taussig shunt (MBTS) had lower early postoperative mortality, but more complications at 14 months. We explored the effect of shunt type and other patient, medical, and surgical factors on postoperative length of stay (LOS) after the Fontan operation.

METHODS

Fontan postoperative course was ascertained from medical record review. Cox proportional hazards modeling was used to identify factors associated with LOS.

RESULTS

Of 327 subjects who underwent Fontan, 323 were analyzed (1 death, 1 biventricular repair, 2 with missing data). Median age and weight at Fontan were 2.8 years (interquartile range [IQR]: 2.3, 3.4) and 12.7 kg (IQR: 11.4, 14.1), respectively. Fontan type was extracardiac in 55% and lateral tunnel in 45%; 87% were fenestrated. The RVPAS and MBTS subjects had similar LOS (median 11 days [IQR: 9, 18] vs 10 days [IQR: 9, 13]; P = .23). Independent risk factors for longer LOS were treatment center (P < .01), LOS at stage II (hazard ratio [HR] 1.02 for each additional day; P < .01), and pre-Fontan complications (HR 1.03 for each additional complication; P = .04). Use of deep hypothermic circulatory arrest at Fontan (HR 0.64; P = .02) was independently associated with shorter LOS. When center was excluded from the model, pre-Fontan complications and use of circulatory arrest were no longer significant; instead, older age at stage II (HR 1.08 for each additional month; P = .01) predicted longer LOS. In 254 subjects who had a pre-Fontan echocardiogram, at least moderate tricuspid regurgitation was independently associated with longer LOS, both with center (HR 1.72; P < .01) and without center in the model (HR 1.49; P = .02).

CONCLUSIONS

In this multicenter prospective cohort of subjects with HLHS, Norwood shunt type was not associated with Fontan LOS. Rather, global measures of earlier medical complexity indicate greater likelihood of longer LOS after the Fontan operation.

Thermal Blanket to Improve Thermoregulation in Preterm Infants: A Randomized Controlled Trial

OBJECTIVE

To determine the effectiveness of temperature-controlled thermal blanket as additional thermoprotection.

DESIGN

Randomized controlled prospective study.

SETTING

Single-center tertiary neonatal unit.

PATIENTS

Inborn very low-birth-weight (< 1,500 g) infants.

INTERVENTIONS

Infants were prospectively assigned to thermal blanket group or control at 1:1 ratio. Additional to radiant warmers, a prewarmed blanket of Blanketrol II (Cincinnati Sub-Zero Products, Cincinnati, OH) was applied as mattress for thermal blanket group. The outcomes included temperature and blood pressure changes. We defined hypothermia as temperature less than 36°C and hypotension as mean arterial pressure less than index infant's gestational age in weeks.

MEASUREMENTS AND MAIN RESULT

Total 80 very low-birth-weight infants were allocated, and there was no between-group demographic dissimilarity. At 30th minute, fewer infants in thermal blanket group were hypothermic (43% vs 68%; p = 0.025). These infants had significantly lower prevalence of hypotension, which associated with less dopamine use in the first 6 hours of life (25% vs 50%; p = 0.016). There was no hyperthermia more than 37.5°C episode.

CONCLUSIONS

By using thermal blanket to provide additional thermal protection for very low-birth-weight infants, the degree of hypothermia was improved, which related to fewer hypotensive cases and less dopamine usage.

Expression of CD11b (MAC-1) and CD162 (PSGL-1) on monocytes is decreased under conditions of deep hypothermic circulatory arrest

Deep hypothermic circulatory arrest (DHCA) is a common technique used to protect vital organs during surgical interventions on the thoracic aorta or during surgery for complex congenital heart disease. Activated leukocytes are key mediators of inflammatory responses during ischemia. Intercellular crosstalk between leukocytes, platelets and endothelial cells is mediated by cell adhesion molecules. These molecules trigger complex cell-cell interaction mechanisms and initiate the release of proinflammatory molecules. One parameter that is known to have a significant impact on inflammatory cell activation and the production of proinflammatory markers is temperature. However, to the best of our knowledge, no data have yet been published on the effect of hypothermia on leukocyte surface markers during DHCA. Thus, the aim of the present study was to investigate the effect of hypothermia on the expression of cell adhesion molecules on monocytes under DHCA conditions in vitro. Blood samples collected from 11 healthy volunteers were incubated in a well-established model simulating circulatory arrest at 36°C and 18°C for 30 min. The expression of cluster of differentiation (CD) molecule 11B (CD11b), CD54 and CD162 on monocytes was measured as the mean fluorescence intensity (MFI) using flow cytometry. The expression level of CD11b on monocytes was significantly decreased following the incubation of the blood samples at 18°C compared with the level in blood samples incubated at 36°C (P<0.001). After 30 min of blood stasis in the circulatory arrest model, the expression level of CD162 on monocytes was significantly lower in the blood samples incubated at 18°C than in those incubated at 36°C (P<0.001). No association was identified between temperature and the surface expression of CD54 on monocytes following 30 min of stasis. These findings demonstrate that deep hypothermia decreases the expression of CD11b and CD162 on monocytes in an experimental setup simulating the conditions of DHCA. This may be the result of the inhibition of leukocyte-endothelial and leukocyte-platelet interactions, which may be a beneficial aspect of deep hypothermia that affects the inflammatory response and tissue damage during DHCA.

Inflammatory response after neonatal cardiac surgery and its relationship to clinical outcomes

BACKGROUND

Cardiac surgery in infants results in a profound inflammatory response secondary to cardiopulmonary bypass (CPB) and the need for blood products. It is not clear how this inflammatory response modulates postoperative course or whether quantification of proinflammatory cytokines can aid with risk stratification. In this study, we prospectively assessed a panel of candidate markers to determine the time course for inflammation and the association of specific markers with clinical outcomes defined as intensive care unit length of stay (LOS).

METHODS

We obtained preoperative blood samples from 92 neonates undergoing surgery with CPB and then serially for 5 days after surgery. Numerous interleukins were assayed along with tumor necrosis factor (TNF)-alpha and interferon (INF)-gamma. The most common surgical procedures were arterial switch procedure (n = 35) and Norwood operation (n = 34). Multivariate analysis was performed to determine if inflammatory mediators could independently predict prolonged intensive care unit LOS.

RESULTS

Compared with the presurgery level, there were statistically significant increases (p < 0.005) for 8 out of 11 inflammatory markers: INF-gamma, interleukin (IL)-10, IL-13, IL-2, IL-5, IL-8, TNF-alpha, and IL-6 after surgery. The only cytokine on the first postoperative day that was independently associated with prolonged length of stay was IL-8 (p = 0.002). Cytokine values measured on postoperative day 3 were most valuable in predicting prolonged LOS. A model that included use of circulatory arrest, and day 3 measures of IL-6 and IL-8 yielded an area under of the curve of 0.88 (95% confidence interval 0.79 to 0.96) for predicting a prolonged LOS.

CONCLUSIONS

In summary, neonatal heart surgery for complex lesions elicits a broad inflammatory response. This early inflammatory response appears nonspecific and did not predict clinical course. Persistence of specific inflammatory mediators on the third day after surgery, however, provided important prognostic information. As such, select cytokines may serve as valuable biomarkers in this population. Whether strategies targeting specific cytokines can alter clinical course is not known.

The effect of cardiopulmonary bypass and hypothermic circulatory arrest on hepatic histology in newborn animals: an experimental study

Still little is known about the effect of cardiac surgery on neonatal hepatic tissue. We examined the effect of cardiopulmonary bypass (CPB) and the effect of deep hypothermic circulatory arrest (DHCA) on neonatal hepatic tissue. Liver biopsies of neonatal piglets were taken after CPB (n = 4), after DHCA (n = 5), and after surgery without CPB (non-CPB; n = 3). Additionally, findings were compared to those of control piglets (n = 9). The liver specimens were fixed, stained with hematoxylin and eosin, and scored regarding inflammatory reaction, hepatocellular edema, and apoptosis. Inflammation score of treated groups was higher than in control; CPB 2.5 ± 0.5, DHCA 1.6 ± 0.4, non-CPB 1.2 ± 0.6, control 0.4 ± 0.3 (P < 0.001 CPB and DHCA vs. control; P < 0.05 non-CPB vs. control). Hepatic cell edema was more evident after DHCA (score 2.0 ± 0.4 vs. 0.2 ± 0.3 in control and 0.6 ± 0.5 after CPB; P < 0.001 and P < 0.05, respectively). The highest apoptotic cell count was in the non-CPB group (22.3 ± 6.3 vs. 11.4 ± 3.6 in control and 8.9 ± 5.4 after CPB; P < 0.05). The present study showed that (i) surgical trauma induces hepatic cell apoptosis; (ii) CPB increases hepatic inflammatory reaction; and (iii) DHCA amplifies hepatic cell edema.

Establishment of a coculture model for studying inflammation after pediatric cardiopulmonary bypass: from bench to bedside

Cardiopulmonary bypass (CPB) has been known to induce an inflammatory response that is influenced by various factors. Hypothermia is supposed to reduce inflammation after CPB. We developed an in vitro coculture model for CPB and compared the effects of hypothermia on the inflammatory response in the coculture model with results from a clinical prospective randomized trial. The coculture model consisted of endothelial cells and monocytes. Cells were stimulated with tumor necrosis factor (TNF)-α and exposed to deep hypothermia (20°C) or normothermia (37°C). In the clinical trial, 20 patients undergoing CPB for ventricular septum defect receive either normothermic (37°C) or mild hypothermic (32°C) CPB. We observed a significant interleukin (IL)-6 and IL-8 release in the coculture model 2 and 24 h after the experimental start. In the clinical trial, cytokines were significantly increased directly after weaning from CPB and remained elevated until 24 h. IL-8 and IL-6 secretions were similar in the hypothermic and normothermic group of the coculture model and the patients after 24 h. These results demonstrate that the inflammatory reaction observed in our coculture model is comparable with the cytokine increase in the blood of children undergoing CPB. Our coculture model could be useful for studies on the mechanisms of CPB-induced inflammation.

Pre-treatment with an intravenous lipid emulsion containing fish oil (eicosapentaenoic and docosahexaenoic acid) decreases inflammatory markers after open-heart surgery in infants: a randomized, controlled trial

BACKGROUND & AIMS

This study assessed the effects of administering a lipid emulsion containing eicosapentaenoic and docosahexaenoic acid before and after open-heart surgery on cytokine production and length of hospital stay in infants.

METHODS

Thirty-two infants (40 ± 2.3 weeks gestational age; 10.6 days at time of surgery) undergoing open-heart surgery with cardiopulmonary bypass were randomized to receive an intravenous lipid emulsion with (treatment) or without (control) eicosapentaenoic and docosahexaenoic acid in this prospective, randomized, double-blind, controlled trial.

RESULTS

Mean plasma TNF-α concentration was significantly (p = 0.003) lower in the treatment (5.9 pg/mL) compared to the control group (14.8 pg/mL). In infants without sepsis, plasma TNF-α did not differ according to treatment, however when sepsis developed, mean plasma TNF-α was 21.1 pg/mL and 1.5 pg/mL (p = 0.0007) in control and treatment groups, respectively. Plasma TNF-α was positively correlated with length of hospital stay in the control group (p = 0.01), and negatively correlated with length of stay in the treatment group (p = 0.004), with a significant time by treatment interaction (p = 0.02).

CONCLUSIONS

Providing a lipid emulsion containing eicosapentaenoic and docosahexaenoic acid reduces TNF-α concentrations in infants undergoing open-heart surgery. Lipid emulsions containing eicosapentaenoic and docosahexaenoic acid may ameliorate the inflammatory response among critically ill infants.

Warm pediatric cardiac surgery: European experience

Cold pediatric cardiac surgery has been a dogma for 50 years. However, the beneficial effects of cold perfusion are counterbalanced by the drawbacks of hypothermia. Thus, we propose a major paradigm shift from hypothermic surgery to warm perfusion and intermittent warm blood cardioplegia. This approach gives satisfactory results even with prolonged aortic crossclamp times. The major advantages are reduced time to extubation and shorter intensive care unit stay. Warm pediatric surgery is an anecdotal phenomenon no more; over 10,000 procedures have been carried out in Europe. All types of cardiopathy have been treated, including arterial switch, total pulmonary anomalous venous return, interruption of the aortic arch, and hypoplastic left heart syndrome. Once surgeons decide to shift from hypothermia to normothermia, they never decide to shift back to hypothermia. This fact is evidence of the satisfactory clinical outcome obtained with this technique. The technique and the composition of microplegia is identical in all European centers, the only variable factor being the interval between microplegia injections, which varies from 10 to 25 min. We hope that the increasing interest in pediatric warm surgery will hearten new candidates.

Cardiac function and circulating cytokines after endotoxin exposure in neonatal mice

Complications after cardiac surgery in neonates can occur because of activation of the inflammatory system. This study used lipopolysaccharide (LPS) endotoxin exposure to cause cytokine activation in neonatal mice and examine left ventricular (LV) function and the effects of antioxidant treatment on cytokine levels. Neonatal mice (6 d old) were injected with either 25 mg/kg LPS (n = 13) or PBS (n = 14), and LV function (echocardiography) was measured at 4 h. Plasma levels of TNF-α, IL-4, IL-6, and IL-10 were measured at 30 min, 1, 2, and 4 h after injection (n = 5 mice per group). Effects of pretreatment with N-acetylcysteine (NAC, 50 mg/kg) on cytokine levels were examined at 2 and 4 h after PBS or LPS (n = 5 mice per group). Four hours after LPS, heart rate was increased (434 ± 14 versus 405 ± 14 bpm, p < 0.05). LV end-diastolic dimension and ejection time were reduced with LPS (both p < 0.05). LPS exposure increased plasma TNF-α, IL-6, and IL-10 levels. NAC pretreatment attenuated the increases in TNF-α and IL-6 levels, but augmented IL-10 levels at 2 h post-LPS. LPS exposure altered cardiac performance and activated cytokines in neonatal mice, which may be ameliorated using antioxidants.

Effect of perfusion temperature on the inflammatory response during pediatric cardiac surgery

BACKGROUND

Cardiopulmonary bypass (CPB) triggers the whole body inflammatory response, and it has been suggested that the degree of hypothermia may influence these responses. The aim of this prospective study was to compare the inflammatory response in children undergoing CPB for repair of congenital heart defects, randomized to mild or moderate hypothermia.

METHODS

We measured inflammatory markers in blood samples of thirty children with body weight less than 10 kg undergoing open heart surgery randomized to surgery at either mild (32 degrees C) or moderate (25 degrees C) hypothermia. Blood was sampled after induction of anesthesia, at skin closure, 2 hours, 24 hours, and 48 hours postoperatively.

RESULTS

Except for an enhanced interleukin-8 response in the moderate hypothermia group, there were no differences in levels of inflammatory mediators between those with mild and those with moderate hypothermia. In contrast to the modest influence of the degree of hypothermia, long CPB time and long aortic cross-clamp time were accompanied by enhanced inflammation involving raised levels of interleukin-8 and myeloperoxidase, as well as increased leukocyte counts.

CONCLUSIONS

Only minor differences in cytokine levels were detected between those with moderate and those with mild hypothermia during CPB. Ischemic aortic cross-clamp time and time on CBP should be as short as possible to avoid an excessive inflammatory response and possibly adverse clinical effects.

Better Protection of Pulmonary Surfactant Integrity With Deep Hypothermia and Circulatory Arrest

BACKGROUND

The influence of deep hypothermia with either circulatory arrest (DHCA) or low-flow (DHLF) perfusion on pulmonary surfactant metabolism in neonates undergoing cardiac surgery remains unknown. This study was conducted to determine the influence of either strategy on surfactant metabolism and pulmonary function with neonatal piglet model.

METHODS

Sixteen piglets underwent 90-minute deep hypothermia, either with circulatory arrest or low-flow perfusion (30 mL.kg(-1).min(-1)) at 18 degrees C. Disaturated phosphatidylcholine, total phospholipids, and total proteins from tracheal aspirates were measured serially until the end of cardiopulmonary bypass. Lung static compliance, airway resistance, and arterial blood oxygen partial pressure to inspired oxygen fraction were also measured.

RESULTS

The DHLF caused more significant decrement of pulmonary static compliance than DHCA (3 +/- 0.4 mL.cmH2O(-1) vs 3.5 +/- 0.3 mL.cmH2O(-1) at 90 minutes of deep hypothermia). Arterial blood oxygen partial pressure to inspired oxygen fraction decreased more significantly after cardiopulmonary bypass in the DHLF group than the DHCA group (205 +/- 84 mm Hg vs 302 +/- 96 mm Hg). The DHLF caused more severe decrement of disaturated phosphatidylcholine total phospholipids (50% +/- 21% vs 67% +/- 23% of baseline at 90 minutes of deep hypothermia) and disaturated phosphatidylcholine total proteins (58% +/- 23% vs 73% +/- 23% of baseline at 90 minutes of deep hypothermia) than DHCA. More significant water retention developed in the lung in the DHLF group than in the DHCA group. The extent of surfactant depletion was statistically correlated with the extent of pulmonary functional deterioration in either group.

CONCLUSIONS

The DHCA induces less injury on pulmonary surfactant metabolism and pulmonary function than DHLF.

Perioperative serum interleukins in neonates with hypoplastic left-heart syndrome and transposition of the great arteries

OBJECTIVE

The primary study objective was to examine the impact of diagnosis on the inflammatory response in neonates with congenital heart disease undergoing cardiac surgery. The secondary objective was to study the impact of the inflammatory response on postoperative outcome in these neonates.

DESIGN

Observational study.

SETTING

Tertiary care children's hospital heart center.

PATIENTS

Neonates with hypoplastic left-heart syndrome (HLHS) undergoing stage I repair and patients with transposition of the great arteries (TGA) undergoing arterial switch operation.

MEASUREMENTS AND MAIN RESULTS

There were 24 neonates with HLHS and 21 neonates with TGA. Serum samples to measure interleukin (IL)-6 and -10 were obtained before and after CPB at 1, 3, 6, and 24 hours postoperatively. Time to extubation, intensive care unit (ICU) length of stay, and peritoneal fluid drainage were compared between the groups. Serum IL-6 and IL-10 concentrations increased after CPB when compared to the preoperative concentration. Preoperative concentrations of IL-6 were significantly elevated in the HLHS group (HLHS: 32 [21.1, 69.6] pg/mL v TGA: 7.2 [3.6, 22.5] pg/mL [median, 25th, and 75th percentile], p = 0.003) and remained elevated immediately after CPB, and at 3 and 6 hours postoperatively. The IL-10 to IL-6 ratio was lower in the HLHS group preoperatively and immediately after CPB. ICU length of stay was significantly longer in the HLHS group (TGA 4 [3-6] days v HLHS 6 [5-8] days, p = 0.031). Mortality in the HLHS group (4/24) was associated with significantly higher IL-6 postoperatively (IL-6 immediately postoperatively: HLHS survivors 59.9 [34.3, 65.7] pg/mL v nonsurvivors 98.7 [94.4, 104.5] pg/mL, p < 0.011).

CONCLUSIONS

All neonates with TGA or HLHS have a significant inflammatory response after CPB. Neonates with HLHS have evidence of an activated inflammatory response before CPB, which remains significant in the postoperative period. Accelerated interleukin expression and an abnormal cytokine balance correlate with longer time to extubation, longer ICU length of stay, and increased peritoneal fluid volume.

Extravasation of albumin after cardiopulmonary bypass in newborns

OBJECTIVE

The systemic inflammatory response to cardiopulmonary bypass (CPB) possibly increases microvascular permeability to plasma proteins, leading to capillary leak syndrome. The study was conducted to elucidate any protein leakage in newborns using Evans blue dye as tracer.

DESIGN

Prospective controlled study.

SETTING

University-affiliated heart center.

PARTICIPANTS

Eleven neonates with transposition of the great arteries.

INTERVENTIONS

Plasma interleukin-6 (IL-6), IL-10, fractional escape rate (FER) of an intravenous bolus of Evans blue, and colloid osmotic pressure (COP) were assessed before and after surgery (statistics: median and 25th-75th percentile, Friedman's 2-way analysis of variance, and Wilcoxon matched-pairs signed-rank test [before and after surgery]).

MEASUREMENTS AND MAIN RESULTS

All patients had an uneventful intraoperative course. The demographic and operative data were age 11 (10-13) days, body weight 3.2 (3.0-3.3) kg, CPB time 132 (123-144) minutes, and aortic cross-clamp time 66 (64-78) minutes. The proinflammatory IL-6 increased 60-fold and the anti-inflammatory IL-10 only 3-fold after CPB. FER, however, was not changed, whereas COP was significantly reduced after CPB.

CONCLUSIONS

In contrast to the expectation, the escape rate of Evans blue, reflecting the extravasation of albumin, was not increased after CPB. However, reduced COP, hypothermia, and also a reduced lymphatic drainage may contribute to edema formation. The present data do not support the hypothesis of a capillary leak after CPB in newborns.

Hypothermic Low-Flow Cardiopulmonary Bypass Impairs Pulmonary and Right Ventricular Function More Than Circulatory Arrest

BACKGROUND

Hypothermic circulatory arrest (HCA) is used during surgical treatment of certain congenital heart defects. The possibility of ischemic neurologic injury associated with HCA has led some surgeons to use low-flow cardiopulmonary bypass (CPB) during the hypothermic interval (hypothermic low flow [HLF]). This study investigates the inflammatory response to HCA and HLF, and reports the consequences of this response on pulmonary and right ventricular function.

METHODS

Piglets (3.1 to 6.6 kg) were cooled to 16 degrees to 18 degrees C using CPB, and randomized: HCA for 60 minutes (n = 7), or HLF (50 cc.kg(-1).min(-1)) for 60 minutes (n = 6). The piglets were rewarmed to 36 degrees C and weaned from CPB. Serum tumor necrosis factor-alpha (TNF-alpha) concentration, percent lung water, and pulmonary and cardiac function were measured before and after CPB.

RESULTS

Tumor necrosis factor-alpha was higher after HLF (2,990.5 +/- 884.5 pg/mL), compared with HCA (347.6 +/- 89.2 pg/mL; p = 0.03). The percent lung water was higher after HLF (84.8% +/- 0.3%) than HCA (82.0% +/- 0.4%; p < 0.001). The alveolar to arterial oxygen gradient was worse after HLF (457 +/- 42 mm Hg) than HCA (285.8 +/- 45 mm Hg; p = 0.02). Pulmonary vascular resistance was greater after HLF (36.08 +/- 8.28 mm Hg.mL(-1).m(-2).min(-1)) than HCA (14.55 +/- 3.46 mm Hg. mL(-1).m(-2).min(-1); p = 0.049). The right ventricular pressure waveform peak derivative, corrected for systolic pulmonary artery pressure, was lower after HLF (14.1 +/- 1.4 sec(-1)), than HCA (23.8 +/- 2.7 sec(-1); p = 0.01).

CONCLUSIONS

Hypothermic low flow extends exposure to CPB, and is associated with an increased inflammatory response compared with HCA. The greater inflammatory response after HLF may result in substantial nonneurologic morbidity in the postoperative period, demonstrated by pulmonary and right ventricular dysfunction. Interventions that attenuate the inflammatory response to CPB may prevent pulmonary and right ventricular dysfunction after HLF.

Steroid Supplementation: A Legitimate Pharmacotherapy After Neonatal Open Heart Surgery

BACKGROUND

An inflammatory response together with multiple organ failure subsequent to cardiopulmonary bypass is especially prominent in neonates. The behavior of glucocorticoids during this period in these patients is not known. If adrenal insufficiency should exist, it could considerably compromise postoperative recovery.

METHODS

Twenty neonates undergoing biventricular repair were enrolled. Ten patients were assigned to receive hydrocortisone treatment and the other 10 to receive placebo. The treatment group received stress-dose hydrocortisone sodium succinate after discontinuation of cardiopulmonary bypass: 0.18 mg.kg(-1).hr(-1) for 3 days, 0.09 mg.kg(-1).hr(-1) for 2 days, and 0.045 mg.kg(-1).hr(-1) for 2 days. The placebo was 5% glucose solution.

RESULTS

Patients had adrenal insufficiency (cortisol < 5 microg/dL) from 24 to 72 hours in the placebo group. This was associated with a simultaneous reduction of left ventricular shortening fraction (p < 0.0001, analysis of variance; p = 0.0203, Student's t test), the necessity to increase inotropic agents (p = 0.043, analysis of variance), and an increase in serum lactate level (p = 0.049, Student's t test). During this period, serum cortisol level was maintained above the normal level (> 23 microg/dL) in the hydrocortisone group. The placebo group had a greater positive fluid balance (p = 0.027, Student's t test) and greater total body edema in the immediate postoperative period (p = 0.065, Student's t test). Blood oxygenation constantly improved, and the duration on mechanical ventilation was shorter (83.5 +/- 42.1 versus 138.2 +/- 89.7 hours; p = 0.098) in the hydrocortisone group.

CONCLUSIONS

Adrenal insufficiency may occur after neonatal open heart surgery. Stress-dose hydrocortisone supplementation blunts other organ dysfunction and can be considered a legitimate pharmacotherapy in this cohort.

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

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

Steroid use before pediatric cardiac operations using cardiopulmonary bypass: an international survey of 36 centers

OBJECTIVE

Steroid administration before pediatric cardiac operations using cardiopulmonary bypass has been shown to modulate the inflammatory response and reduce myocardial injury. We hypothesized that current steroid administration practices among pediatric cardiac surgical centers are highly variable.

DESIGN

Questionnaire survey.

SETTING

Pediatric intensive care units.

SUBJECTS

All members of the Pediatric Cardiac Intensive Care Society.

INTERVENTIONS

A self-administered survey was sent to >130 members and 70 institutions participating in the Pediatric Cardiac Intensive Care Society.

MEASUREMENTS AND MAIN RESULTS

Thirty-six questionnaires were returned: 14 international and 22 domestic centers. Cumulatively, these centers treat >11,000 pediatric cardiac patients per year. Ninety-seven percent (35 of 36) of these centers report the use of steroids before cardiopulmonary bypass, yet only 40% (14 of 35) administer steroids with every case. Of the 21 centers that selectively use steroids, 12 do so only for neonates, five administer steroids based on surgeon preference, and four administer steroids for cases anticipated to involve bypass time >2 hrs or deep hypothermic circulatory arrest. Of the 35 centers using steroids, 11 deliver a single dose in the circuit prime, 18 administer a single dose to the patient, and six give multiple doses. The timing of the steroid dose to the patient is variable; 12 centers administer a dose on induction of anesthesia; six centers administer the dose 2-12 hrs before operation. Regimens in the six centers using multiple doses of steroids before cardiopulmonary bypass are as follows: administration at induction and in the prime (two centers); 12 hrs preoperatively and at induction (one center); prime, induction, and 6 hrs preoperatively (one center); prime and midnight preoperatively (one center); and prime plus 2 and 8 hrs preoperatively (one center). Eight centers continue steroid administration following bypass.

CONCLUSION

Although nearly all centers surveyed administer steroids before cardiopulmonary bypass, the type, dosing, route, and timing of administration are highly variable. The inconsistencies in these data and the pediatric literature would support the undertaking of a large, multiple-center clinical trial to evaluate the risks and benefits of steroid administration before pediatric cardiopulmonary bypass.

Different Proinflammatory Cytokine Serum Pattern in Neonate Patients Undergoing Open Heart Surgery. Relevance of IL-8

The purpose of this work was to investigate the clinical significance of serum levels of proinflammatory cytokines in pediatric patients undergoing cardiopulmonary bypass. We divided the patients in two groups: 8 neonates, and 19 non-newborn children. IL-1beta, IL-6, IL-8, and TNF serum levels were quantified before sternotomy, at admission to the PICU (30 min postoperatively), 24 h after the onset of surgery and 3 days after the operation. Surgical cardiac stress elicits significant increments of IL-6, IL-8 and TNF serum concentrations in both neonates and non-neonates, regardless of their preoperative clinical condition. However, in newborns the magnitude of the proinflammatory cytokine increments was, in particular with IL-8, remarkably greater than in older children. Moreover, neonate and non-neonate patients showed clearly disparate patterns of serum concentrations over time of both IL-8 and TNF. There was a marked relationship between IL-8 levels and postoperative morbidity, evaluated by pulmonary dysfunction, days on inotropic support and days of PICU stay in both neonates and non-neonates patients. In contrast, we found no relationship between serum levels of IL-6 and TNF and postoperative clinical data. Newborn and non-newborn patients undergoing cardiopulmonary bypass exhibit dissimilar patterns of proinflammatory cytokines. IL-8 might be implicated in the multiorganic dysfunction related to cardiopulmonary bypass in pediatric patients.

Periventricular leukomalacia following neonatal and infant cardiac surgery

The dramatic reduction in surgical mortality following repair of congenital heart defects has been accompanied by increasing recognition of adverse neurodevelopmental sequelae in some children. Neurodevelopmental abnormalities following neonatal and infant cardiac surgery include mild cognitive impairment, expressive speech and language abnormalities, impaired attention and executive function, impaired visual and spatial motor skills, as well as learning disabilities. These defects result in a significant need for early intervention, as well as rehabilitative and special education services. Central nervous system injury following repair of congenital heart defects results from a complex interaction of patient specific and environmental factors. Recent studies suggest that cerebral white matter injury characterized by periventricular leukomalacia (PVL) is common in infants with congenital heart disease particularly following cardiac surgery. Studies at our institution show that this occurs in greater than 50% of neonates following cardiac surgery, but is rare in older infants. Prolonged exposure to cardiopulmonary bypass (with or without deep hypothermic circulatory arrest) is a risk factor for PVL, possibly secondary to the systemic inflammatory response to cardiopulmonary bypass. Hypotension and hypoxemia in the early postoperative period, especially diastolic hypotension, significantly increase the risk of PVL. Future studies are needed to determine significance of PVL as a marker for long-term developmental dysfunction.