Complement activation in coronary artery bypass grafting patients without cardiopulmonary bypass: the role of tissue injury by surgical incision

Whole Blood Reactivity to Viral and Bacterial Pathogens after Non-Emergent Cardiac Surgery during the Acute and Convalescence Periods Demonstrates a Distinctive Profile of Cytokines Production Compared to the Preoperative Baseline in Cohort of 108 Patients, Suggesting Immunological Reprogramming during the 28 Days Traditionally Recognized as the Post-Surgical Recovery Period

The release of danger signals from tissues in response to trauma during cardiac surgery creates conditions to reprogram the immune system to subsequent challenges posed by pathogens in the postoperative period. To demonstrate this, we tested immunoreactivity before surgery as the baseline (tbaseline), followed by subsequent challenges during the acute phase (t24h), convalescence (t7d), and long-term recovery (t3m). For 108 patients undergoing elective heart surgery, whole blood was stimulated with lipopolysaccharide (LPS), Influenza A virus subtype N2 (H3N2), or the Flublok™ vaccine to represent common pathogenic challenges. Leukocytosis, platelet count, and serum C-reactive protein (CRP) were used to measure non-specific inflammation. Cytokines were measured after 18 h of stimulation to reflect activation of the various cell types (activated neutrophils-IL-8; activated T cells-IL-2, IFNγ, activated monocyte (MO)-TNFα, IL-6, and deactivated or atypically activated MO and/or T cells-M-CSF, IL-10). IL-2 and IL-10 were increased at t7d, while TNFα was suppressed at t24h when LPS was utilized. Interestingly, M-CSF and IL-6 production was elevated at seven days in response to all stimuli compared to baseline. While some non-specific markers of inflammation (white cell count, IL-6, and IL-8) returned to presurgical levels at t3m, CRP and platelet counts remained elevated. We showed that surgical stimulus reprograms leukocyte response to LPS with only partial restoration of non-specific markers of inflammation.

Incidence and outcome of anaphylaxis in cardiac surgical patients

Introduction:

Anaphylaxis is a rare but serious and potentially fatal complication of anesthesia. Little is known about the incidence and outcome of anaphylaxis in cardiac surgical patients, which we aimed to investigate.

Methods:

This was a 21-year retrospective study of cardiac surgical patients at Manchester Royal Infirmary, Manchester Foundation Trust, Manchester, UK.

Results:

A total of 19 cases of anaphylaxis were reported among 17,589 patients (0.108%) undergoing cardiac surgery. The majority (15/19) occurred before cardiopulmonary bypass (CPB), mostly during or within 30 min after the induction of anesthesia (10/19). Two occurred within 15 min of going onto CPB. Of these 17 cases, 11 were abandoned, and 6 proceeded. The severity of reactions in the patients who proceeded ranged from grade II to grade IV of the Ring and Messmer classification. Two cases occurred after the completion of surgery. All patients survived to 90 days. However, this did not appear to be related to CPB or protamine as most of the reactions occurred before CPB. Instead, the most common causative agents were gelofusine, antibiotics, muscle relaxants, and chlorhexidine. In 6 cases, surgery proceeded despite the anaphylaxis, in 11 cases the surgery was postponed, and in 2 cases the procedure had already been completed.

Conclusion:

As all patients survived, our results provide preliminary support for proceeding with surgery although we cannot speculate on the likely outcomes of patients who were postponed, had their surgery proceeded. Based on our data, the incidence of anaphylaxis in cardiac surgical patients may be 10–20 times higher than in the general surgical population.

Acute Respiratory Distress Syndrome in the Perioperative Period of Cardiac Surgery: Predictors, Diagnosis, Prognosis, Management Options, and Future Directions

Acute respiratory distress syndrome (ARDS) after cardiac surgery is reported with a widely variable incidence (from 0.4%-8.1%). Cardiac surgery patients usually are affected by several comorbidities, and the development of ARDS significantly affects their prognosis. Herein, evidence regarding the current knowledge in the field of ARDS in cardiac surgery is summarized and is followed by a discussion on therapeutic strategies, with consideration of the peculiar aspects of ARDS after cardiac surgery. Prevention of lung injury during and after cardiac surgery remains pivotal. Blood product transfusions should be limited to minimize the risk, among others, of lung injury. Open lung ventilation strategy (ventilation during cardiopulmonary bypass, recruitment maneuvers, and the use of moderate positive end-expiratory pressure) has not shown clear benefits on clinical outcomes. Clinicians in the intraoperative and postoperative ventilatory settings carefully should consider the effect of mechanical ventilation on cardiac function (in particular the right ventricle). Driving pressure should be kept as low as possible, with low tidal volumes (on predicted body weight) and optimal positive end-expiratory pressure. Regarding the therapeutic options, management of ARDS after cardiac surgery challenges the common approach. For instance, prone positioning may not be easily applicable after cardiac surgery. In patients who develop ARDS after cardiac surgery, extracorporeal techniques may be a valid choice in experienced hands. The use of neuromuscular blockade and inhaled nitric oxide can be considered on a case-by-case basis, whereas the use of aggressive lung recruitment and oscillatory ventilation should be discouraged.

Complement activation during cardiopulmonary bypass and association with clinical outcomes

In this prospective, single-centre observational study of 30 patients undergoing cardiopulmonary bypass (CPB), the effect of unfractionated heparin (UFH), CPB surgery and protamine sulphate on complement and on post-operative blood loss were assessed. Although C3 and C4 levels decreased significantly immediately following the administration of UFH, C3a, C5a, Bb fragment and SC5b-9 remained unchanged. During CPB, C3 and C4 continued to fall whilst both alternative and classical pathways activation markers, Bb, C3a, C5a and SC5b-9 increased significantly. Protamine sulphate had no effect on classical pathway components or activation markers but decreased alternative pathway activation marker Bb. Over the 12-24 h post-surgery, both classical and alternative pathway activation markers returned to baseline, whilst C3 and C4 levels increased significantly but not to baseline values. Total drain volume 24 h after the surgery showed a moderate inverse correlation with post-protamine C3 (r = -0.46, p = 0.01) and C4 (r = -0.57, p = 0.0009) levels, whilst a moderate positive correlation was observed with post-protamine C3a (r = 0.46, p = 0.009), C5a (r = 0.37, p = 0.04) and SC5b-9 (r = 0.56, p = 0.001) levels but not with Bb fragment (r = 0.25, p = 0.17). Thus, inhibition of complement activation may be a therapeutic intervention to reduce post-operative blood in patients undergoing CPB.

Novel biomarkers in cardiovascular surgery

Cardiovascular disease includes health problems related to the heart, arteries and veins and is a significant healthcare problem worldwide. Cardiovascular disease may be acute or chronic and relapses are frequent. Biomarkers involved in this field may help clinicians and surgeons in diagnosis and adequate decision making. Relevant articles searched in the following databases Medline, Scopus, ScienceDirect, were retrieved and analysed. Several biomarkers have been identified and we analyzed those of most importance from a clinical and surgical point of view. Biomarkers can better identify high-risk individuals, facilitate follow-up process, provide information regarding prognosis and better tailor the most appropriate surgical treatment.

Changes in inflammation and oxidative stress signalling pathways in coarcted aorta triggered by bicuspid aortic valve and growth in young children

Neonates with coarctation of the aorta (CoA) combined with a bicuspid aortic valve (BAV) show significant structural differences compared to neonatal CoA patients with a normal tricuspid aortic valve (TAV). These effects are likely to change over time in response to growth. This study investigated proteomic differences between coarcted aortic tissue of BAV and TAV patients in children older than one month. Aortic tissue just proximal to the coarctation site was collected from 10 children (BAV; n=6, 1.9±1.7 years, TAV; n=4, 1.7±1.5 years, (mean ± SEM, P=0.92.) Tissue were snap frozen, proteins extracted, and the extracts used for proteomic and phosphoproteomic analysis using Tandem Mass Tag (TMT) analysis. A total of 1811 protein and 76 phosphoprotein accession numbers were detected, of which 40 proteins and 6 phosphoproteins were significantly differentially expressed between BAV and TAV patients. Several canonical pathways involved in inflammation demonstrated enriched protein expression, including acute phase response signalling, EIF2 signalling and macrophage production of IL12 and reactive oxygen species. Acute phase response signalling also demonstrated enriched phosphoprotein expression, as did Th17 activation. Other pathways with significantly enriched protein expression include degradation of superoxide radicals and several pathways involved in apoptosis. This work suggests that BAV CoA patients older than one month have an altered proteome consistent with changes in inflammation, apoptosis and oxidative stress compared to TAV CoA patients of the same age. There is no evidence of structural differences, suggesting the pathology associated with BAV evolves with age in paediatric CoA patients.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Evaluation of a new condensed extra-corporeal circuit for cardiac surgery: a prospective randomized clinical pilot study

This prospective randomized clinical pilot study was conducted to evaluate a recently introduced reduced volume CPB system that is coated with the biopassive Xcoating™. Twenty-two patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB), either with a fully heparin-coated CPB circuit (control, n=11) or with an Xcoating™ coated condensed extra-corporeal circuit (CondECC, n=11), were included.

We examined activation of the complement system (C3bc and C4bc), activation of neutrophils (BPI), the acute phase response (interleukin (IL)-6, and acute phase proteins (LBP, AGP, and CRP)), myocardial tissue injury (troponin T), hemolysis (free hemoglobin (FHb)), and clinical outcome parameters. Preoperative risk profiles were identical for both patient groups. All patients went through the procedure without major complications and were discharged from the hospital. FHb and BPI levels at the end of pump support ( p <0.01) and at 15 min after the administration of protamine ( p <0.05) were significantly higher in the control group. In addition, FHb levels were still significantly elevated upon arrival on the cardiothoracic intensive care unit (CICU) in the control group ( p <0.05). C3bc and C4bc, acute phase proteins, IL-6, and troponin T concentrations, and clinical outcome variables were identical in both patient groups.

In conclusion, the evaluated condensed extracorporeal circuit is a flexible and multifunctional CPB sytem that offers safe procedures. Furthermore, the results indicate improved biocompatibility of this option for extracorporeal circulation.

Leukocyte filtration and aprotinin: synergistic anti-inflammatory protection

Cardiopulmonary bypass activates an array of cellular and humoral inflammatory mechanisms that culminate in diverse or organ-specific injury. A manifestation of inflammatory injury to the heart, atrial fibrillation ranks among the most frequent and potentially life-threatening postsurgical complications. Pulmonary manifestations of the inflammatory response are also of major concern. Neutrophils activated by passage through the extracorporeal circuit inflict local injury and provoke the inflammatory cascade by producing oxyradicals and proinflammatory factors. This study tested if a combination of leukocyte depletion and aprotinin suppression of neutrophils could minimize postbypass atrial fibrillation and pulmonary dysfunction. In part one, two randomized groups of 90 patients undergoing primary coronary artery bypass grafting received full Hammersmith aprotinin alone (control group) or combined with leukofiltration (study group) and were prospectively examined. The dual treatment decreased the incidence of postoperative atrial fibrillation (7 of 90, 7.8%) by 67% versus aprotinin alone (21 of 90, 23.3%). Respiratory gas exchange in these patients was assessed from pulmonary shunt fraction. In the first two hours postbypass, pulmonary shunt fraction in the dual treatment group increased 40% less than in the group receiving aprotinin alone (p = 0.002), and subsided more quickly and completely over the next six hours. In part two, the cardiopulmonary bypass group receiving aprotinin+leukofiltration was retrospectively compared with 45 patients undergoing off-pump coronary revascularization. A strong, albeit not statistically significant trend (p= 0.08) toward a lower incidence of atrial fibrillation was found in the dual treatment group versus the off-pump group (8 of 45, 17.8%). These findings suggest that combining mechanical and pharmacologic suppression of the systemic inflammatory response could mitigate its deleterious arrhythmic and pulmonary complications.

First In Vivo Results of a Novel Pediatric Oxygenator with an Integrated Pulsatile Pump

Extracorporeal membrane oxygenation (ECMO) is a pivotal bridge to recovery for cardiopulmonary failure in children. Besides its life-saving quality, it is often associated with severe system-related complications, such as hemolysis, inflammation, and thromboembolism. Novel oxygenator and pump systems may reduce such ECMO-related complications. The ExMeTrA oxygenator is a newly designed pediatric oxygenator with an integrated pulsatile pump minimizing the priming volume and reducing the surface area of blood contact. The aim of our study was to investigate the feasibility and safety of this new ExMeTrA (expansion mediated transport and accumulation) oxygenator in an animal model. During 6 h of extracorporeal circulation (ECC) in pigs, parameters of the hemostatic system including coagulation, platelets and complement activation, and flow rates were investigated. A nonsignificant trend in C3 consumption, thrombin-antithrombin-III (TAT) complex formation and a slight trend in hemolysis were detected. During the ECC, the blood flow was constantly at 500 ml/min using only flexible silicone tubes inside the oxygenator as pulsatile pump. Our data clearly indicate that the hemostatic markers were only slightly influenced by the ExMeTrA oxygenator. Additionally, the oxygenator showed a constant quality of blood flow. Therefore, this novel pediatric oxygenator shows the potential to be used in pediatric and neonatal support with ECMO.

Similarity of coagulation and inflammation despite different surgical revascularization strategies – a prospective randomized trial

Background:

Supposedly, minimized extracorporeal circulation or off-pump revascularization as alternatives to conventional extracorporeal circulation (ONCAB) reduce inflammation and coagulation disturbances.

Methods:

One hundred and twenty coronary artery bypass graft (CABG) patients were prospectively randomized for three surgical techniques. Coagulation and inflammation markers were measured up to 72 hours postoperatively.

Results:

Coagulation factors I, II, V, X, antithrombin III and C-reactive protein did not differ perioperatively between the groups and increased, as did several other markers, 12 to 72 hours postoperatively. Compared to its alternatives, ONCAB showed the most obvious transient increase in thrombin-antithrombin complexes (p<0.0001), D-dimers (p=0.0059), tissue factor pathway inhibitor (p=0.0005), factor VIII (p=0.0041) and tumor necrosis factor α (p=0.0300) during the operation and up to 12 hours postoperatively. Furthermore, ONCAB generated lower leukocyte and platelet counts and higher values of soluble P-selectin and soluble intercellular adhesion molecule 1 at some time points.

Conclusions:

With similarity in pivot coagulation factors, a specific detrimental influence of ONCAB on common coagulation pathways was excluded. Higher perioperative concentrations of products from the coagulation cascade most likely indicate activation of pericardial blood – recirculated only in ONCAB. Furthermore, with only temporary differences in markers of inflammation, the alternatives to ONCAB altogether were without advantage at 72 hours postoperatively. In the general answer to surgical trauma, the part of modern extracorporeal circulation is possibly overestimated. The study is registered at the German Clinical Trial Registry. Registration number DRKS00007580. URL: https://drks-neu.uniklinik-freiburg.de/drks_web/ URL: http://apps.who.int/trialsearch/

Off-Pump Coronary Artery Bypass Surgery

Off-pump coronary artery bypass surgery has been adopted enthusiastically worldwide. However, despite more than 6 years’ experience and refinement, many surgeons use it only sporadically and some hardly at all. This reluctance persists despite support for the procedure because of the lack of properly designed risk models and/or randomized studies. Although it has not been overwhelmingly shown that off-pump surgery is superior to the conventional on-pump procedure, the technique has its place in our specialty. It has been shown to be better for noncritical end points in selected patients in the hands of selected surgeons. That there are differences in surgical skill among surgeons is something we all know but rarely discuss in public. Until now, disparities in skill have been most salient with uncommon and extraordinarily challenging operations. Perhaps the off-pump procedure should be regarded as the “challenging” aspect of coronary artery bypass surgery, and self-restraint may need to remain in force if we are to continue to achieve the highest level of clinical excellence.

Postoperative cognitive dysfunction and neuroinflammation; Cardiac surgery and abdominal surgery are not the same

Postoperative cognitive dysfunction (POCD) is a debilitating surgical complication, with cardiac surgery patients at particular risk. To gain insight in the mechanisms underlying the higher incidence of POCD after cardiac versus non-cardiac surgery, systemic and central inflammatory changes, alterations in intraneuronal pathways, and cognitive performance were studied after cardiac and abdominal surgery in rats. Male Wistar rats were subjected to ischemia reperfusion of the upper mesenteric artery (abdominal surgery) or the left coronary artery (cardiac surgery). Control rats remained naïve, received anesthesia only, or received thoracic sham surgery. Rats were subjected to affective and cognitive behavioral tests in postoperative week 2. Plasma concentrations of inflammatory factors, and markers for neuroinflammation (NGAL and microglial activity) and the BDNF pathway (BDNF, p38MAPK and DCX) were determined. Spatial memory was impaired after both abdominal and cardiac surgery, but only cardiac surgery impaired spatial learning and object recognition. While all surgical procedures elicited a pronounced acute systemic inflammatory response, NGAL and TNFα levels were particularly increased after abdominal surgery. Conversely, NGAL in plasma and the paraventricular nucleus of the hypothalamus and microglial activity in hippocampus and prefrontal cortex on postoperative day 14 were increased after cardiac, but not abdominal surgery. Both surgery types induced hippocampal alterations in BDNF signaling. These results suggest that POCD after cardiac surgery, compared to non-cardiac surgery, affects different cognitive domains and hence may be more extended rather than more severe. Moreover, while abdominal surgery effects seem limited to hippocampal brain regions, cardiac surgery seems associated with more wide spread alterations in the brain.

Addressing the Global Burden of Trauma in Major Surgery

Despite a technically perfect procedure, surgical stress can determine the success or failure of an operation. Surgical trauma is often referred to as the "neglected step-child" of global health in terms of patient numbers, mortality, morbidity, and costs. A staggering 234 million major surgeries are performed every year, and depending upon country and institution, up to 4% of patients will die before leaving hospital, up to 15% will have serious post-operative morbidity, and 5-15% will be readmitted within 30 days. These percentages equate to around 1000 deaths and 4000 major complications every hour, and it has been estimated that 50% may be preventable. New frontline drugs are urgently required to make major surgery safer for the patient and more predictable for the surgeon. We review the basic physiology of the stress response from neuroendocrine to genomic systems, and discuss the paucity of clinical data supporting the use of statins, beta-adrenergic blockers and calcium-channel blockers. Since cardiac-related complications are the most common, particularly in the elderly, a key strategy would be to improve ventricular-arterial coupling to safeguard the endothelium and maintain tissue oxygenation. Reduced O2 supply is associated with glycocalyx shedding, decreased endothelial barrier function, fluid leakage, inflammation, and coagulopathy. A healthy endothelium may prevent these "secondary hit" complications, including possibly immunosuppression. Thus, the four pillars of whole body resynchronization during surgical trauma, and targets for new therapies, are: (1) the CNS, (2) the heart, (3) arterial supply and venous return functions, and (4) the endothelium. This is termed the Central-Cardio-Vascular-Endothelium (CCVE) coupling hypothesis. Since similar sterile injury cascades exist in critical illness, accidental trauma, hemorrhage, cardiac arrest, infection and burns, new drugs that improve CCVE coupling may find wide utility in civilian and military medicine.

Protection strategies during cardiopulmonary bypass: ventilation, anesthetics and oxygen

PURPOSE OF REVIEW

To provide an update of research findings regarding the protection strategies utilized for patients undergoing cardiopulmonary bypass (CPB), including perioperative ventilatory strategies, different anesthetic regimens, and inspiratory oxygen fraction. The article will review and comment on some of the most important findings in this field to provide a global view of strategies that may improve patient outcomes by reducing inflammation.

RECENT FINDINGS

Postoperative complications are directly related to ischemia and inflammation. The application of lung-protective ventilation with lower tidal volumes and higher positive end-expiratory pressure reduces inflammation, thereby reducing postoperative pulmonary complications. Although inhalation anesthesia has clear cardioprotective effects compared with intravenous anesthesia, several factors can interfere to reduce cardioprotection. Hyperoxia up to 0.8 FiO(2) may confer benefits without increasing oxidative stress or postoperative pulmonary complications. During the early postoperative period, inhalation anesthesia prior to extubation and the application of preventive noninvasive ventilation may reduce cardiac and pulmonary complications, improving patients' outcomes.

SUMMARY

Lung-protective mechanical ventilation, inhalation anesthesia, and high FiO(2) have the potential to reduce postoperative complications in patients undergoing CPB; however, larger, well powered, randomized control trials are still needed.

Minithoracotomy versus sternotomy for mitral surgery in patients with chronic renal impairment: a propensity-matched study

OBJECTIVE

Compared with median sternotomy, a right thoracotomy (RT) approach to mitral surgery is associated with decreased postoperative acute renal failure. Therefore, we examined propensity-matched patients with chronic renal impairment to compare outcomes.

METHODS

A retrospective review at a single institution identified patients who underwent mitral valve surgery from 1986 to 2010. After excluding patients who had procedures that were not usually performed through an RT approach, 2306 patients were identified. Of this group, we found 446 patients with preoperative creatinines of 1.3 mg/dL or greater. Using propensity score matching based on comorbidities, operative year, and surgeon, 90 matched patients in each group were included.

RESULTS

There was no difference in the median year of operation. Postoperative mortality is 20% lower for the RT group (P = 0.037) using Mantel-Cox statistics. This greater survival in the RT group occurred early within the first year and was maintained on long-term follow-up. The RT approach was also associated with a Cox proportional hazard for mortality of 0.528 (P = 0.006). Incidence of postoperative complications with an RT approach was lower in terms of acute renal failure (10% vs 21%, P = 0.05), stroke (1% vs 9%, P = 0.017), and permanent pacemaker insertion (3% vs 11%, P = 0.044). Right thoracotomy was associated with lower chest tube outputs (503 vs 1333 mL, P < 0.001).

CONCLUSIONS

The RT approach was associated with lower postoperative mortality and morbidity in patients with impaired renal function. The RT approach to the mitral valve may be preferred in this high-risk population.

Elevated preoperative neutrophil/lymphocyte ratio as a predictor of increased long-term survival in minimal invasive coronary artery bypass surgery compared to sternotomy

Background

Neutrophil lymphocyte ratio (NLR) is a predictor of major adverse cardiovascular outcomes. Our study explores the value of NLR in predicting long-term mortality after minimally invasive coronary artery bypass surgery (MICS) via lateral left-thoracotomy versus conventional sternotomy coronary artery bypass grafting (CABG) surgery.

Methods

A total of 1126 consecutive patients (729 sternotomy CABG and 397 MICS) from a single tertiary center between 2005 and 2008 were followed until 2011. We stratified the patients into equal tertiles according to preoperative NLR. The primary outcome, all-cause mortality, was compared among the NLR tertiles.

Results

Out of the 1126 patients included in the study, 1030 (91%) patients underwent off-pump CABG . The first (NLR <2.3) tertile had a significantly lower 5-year mortality (30/371 =8%) in comparison to the second (NLR =2.3-3.4) and third (NLR ≥3.5) tertiles (49/375 =13% and 75/380 =20%), respectively with p < 0.0001. After multivariate adjustment, NLR was a significant independent predictor of mortality (hazard ratio [HR] per each unit increase of NLR was 1.05, 95% confidence interval [CI] 1.01-1.10, p = 0.008). MICS and sternotomy CABG groups with NLR <3 had similar mortality (21/221 =9.5% and 40/403 =9.9%), p = 1. However among patients with NLR ≥3, MICS had a significantly lower mortality (23/176 = 13.1%) compared to the sternotomy CABG (70/326 =21.5%), p = 0.02. According to the multivariate analysis of patients with NLR ≥3, MICS had a significantly lower mortality compared to sternotomy CABG (HR = 0.44, 95% CI 0.24-0.78, p = 0.005).

Conclusion

Elevated preoperative NLR is an independent predictor of long-term mortality after CABG. Among the patients with NLR ≥ 3, MICS was associated with a significantly improved survival compared with sternotomy CABG.

Does use of cell saver decrease the inflammatory response in cardiac surgery?

BACKGROUND

The role of a cell-saver device in the inflammatory response to cardiac surgery has not been well documented. We hypothesized that the use of a cell saver may reduce proinflammatory cytokine concentrations in patients undergoing cardiac surgery.

METHODS

57 patients presenting for first-time nonemergency cardiac surgery were prospectively randomized to control or cell salvage groups. Blood samples for inflammatory marker assays were collected from the arterial line on induction of anesthesia, at the end of cardiopulmonary bypass, 1 h after surgery, and 24 h after surgery. Plasma proinflammatory cytokines were analyzed using a sandwich solid-phase enzyme-linked immunosorbent assay.

RESULTS

The highest cytokine levels were observed 1 h after surgery. When comparing serum interleukin levels in both patient groups during the different perioperative periods, we found a higher interleukin-8 concentration 24 h after the procedure, and higher concentrations of the p40 subunit of interleukin-12 at 1 h and 24 h postoperatively. The concentrations of interleukin-6 and p40 were greater in blood stored by the cardiotomy suction system than in blood processed by the cell saver (p = 0.01 in both cases). The interleukin-8 concentration was higher in the blood processed by the cell saver (p = 0.03). No significant differences were observed in interleukin-1 and interferon gamma levels in blood from both systems. Clinical outcomes were similar in both groups.

CONCLUSIONS

Our results suggest that cell salvage in low-risk patients undergoing their first elective cardiac procedure does not decrease the inflammatory response after surgery.

Are blood stream infections associated with an increased risk of hemorrhagic stroke in patients with a left ventricular assist device?

Blood stream infections (BSIs) are an important cause of morbidity and mortality in patients with left ventricular assist devices (LVADs). The aim of this study was to examine the correlation between hemorrhagic cerebrovascular accident (CVA) and BSI after implantation of LVAD for advanced heart failure (HF). This was a retrospective descriptive review of 87 patients with end-stage HF, who underwent implantation of HeartMate II continuous-flow LVAD over a 4 year period. Blood stream infections were diagnosed by serial blood cultures, and suspected neurological complications including CVAs were confirmed by neuroimaging. Extensive patient chart review was performed, and descriptive characteristics were analyzed using SPSS statistical software. The mean age of our study population was 62.3 ± 12.8 years, and the majority of our patients were males (n = 75, 86.2%). The baseline characteristics were comparable in the patients with and without CVAs. Patients with BSI had a much greater incidence of CVA compared to patients without BSI (n = 13, 43.3% vs. n = 5, 10.0%; p < 0.0001). There was an increased mortality in patients with BSI than those without (n = 57, 65.5% vs. n = 30, 34.5%; p = 0.003). The risk of all CVAs (hemorrhagic/ischemic) was eightfold (odds ratio [OR] = 7.9; 95% confidence interval [CI] = 2.4-25.5; p = 0.001] in patients with BSI. Patients with BSI had a >20-fold risk of hemorrhagic CVA (OR = 24; 95% CI = 2.8-201.1; p = 0.03). Advanced HF patients with LVAD support who developed BSI need urgent evaluation and close monitoring for suspected neurological complications, particularly hemorrhagic CVA.

Complement activation and cardiac surgery: a novel target for improving outcomes

Complement activation and the resulting inflammatory response is an important potential mechanism for multisystem organ injury in cardiac surgery. Novel therapeutic strategies using complement inhibitors may hold promise for improving outcomes for cardiac surgical patients by attenuating complement activation or its biologically active effector molecules. Recent clinical trials evaluating complement inhibitors have provided important data to further delineate the impact of complement activation and its inhibition on clinical outcomes. In this review we examine the role of complement activation and its inhibition as a therapeutic approach in cardiac surgery.

Cardiopulmonary bypass model in the rat: a new minimal invasive model with a low flow volume

Numerous cardiopulmonary bypass (CPB) models in the rat have already been described, but these models often have an important mortality and differ a lot from human clinical conditions thus making them hardly usable. The CPB model in the rat we describe allows a femoro-femoral support CPB with a low priming volume, minimal surgical approach and excellent peroperative survival. This CPB model in the rat allows evaluating extracorporeal circulation effects.

The cellular and molecular origin of reactive oxygen species generation during myocardial ischemia and reperfusion

Myocardial ischemia-reperfusion injury is an important cause of impaired heart function in the early postoperative period subsequent to cardiac surgery. Reactive oxygen species (ROS) generation increases during both ischemia and reperfusion and it plays a central role in the pathophysiology of intraoperative myocardial injury. Unfortunately, the cellular source of these ROS during ischemia and reperfusion is often poorly defined. Similarly, individual ROS members tend to be grouped together as free radicals with a uniform reactivity towards biomolecules and with deleterious effects collectively ascribed under the vague umbrella of oxidative stress. This review aims to clarify the identity, origin, and progression of ROS during myocardial ischemia and reperfusion. Additionally, this review aims to describe the biochemical reactions and cellular processes that are initiated by specific ROS that work in concert to ultimately yield the clinical manifestations of myocardial ischemia-reperfusion. Lastly, this review provides an overview of several key cardioprotective strategies that target myocardial ischemia-reperfusion injury from the perspective of ROS generation. This overview is illustrated with example clinical studies that have attempted to translate these strategies to reduce the severity of ischemia-reperfusion injury during coronary artery bypass grafting surgery.

C1-esterase inhibitor protects against early vein graft remodeling under arterial blood pressure

OBJECTIVES

Arterial pressure induced vein graft injury can result in endothelial loss, accelerated atherosclerosis and vein graft failure. Inflammation, including complement activation, is assumed to play a pivotal role herein. Here, we analyzed the effects of C1-esterase inhibitor (C1inh) on early vein graft remodeling.

METHODS

Human saphenous vein graft segments (n=8) were perfused in vitro with autologous blood either supplemented or not with purified human C1inh at arterial pressure for 6h. The vein segments and perfusion blood were analyzed for cell damage and complement activation. In addition, the effect of purified C1inh on vein graft remodeling was analyzed in vivo in atherosclerotic C57Bl6/ApoE3 Leiden mice, wherein donor caval veins were interpositioned in the common carotid artery.

RESULTS

Application of C1inh in the in vitro perfusion model resulted in significantly higher blood levels and significantly more depositions of C1inh in the vein wall. This coincided with a significant reduction in endothelial loss and deposition of C3d and C4d in the vein wall, especially in the circular layer, compared to vein segments perfused without supplemented C1inh. Administration of purified C1inh significantly inhibited vein graft intimal thickening in vivo in atherosclerotic C57Bl6/ApoE3 Leiden mice, wherein donor caval veins were interpositioned in the common carotid artery.

CONCLUSION

C1inh significantly protects against early vein graft remodeling, including loss of endothelium and intimal thickening. These data suggest that it may be worth considering its use in patients undergoing coronary artery bypass grafting.

Perioperative management of a patient with hereditary angioedema during off-pump coronary artery bypass graft surgery

The case of a patient with hereditary angioedema (HAE), a rare, life-threatening disorder caused by reduced activity of the C1 esterase inhibitor, and requiring off-pump coronary artery bypass graft (OP-CABG) surgery, is presented. Perioperative management of patients with HAE who undergo complex cardiac surgical procedures are discussed, including an OP-CABG surgical approach to decrease complement activation, fresh-frozen plasma administration to increase C1 esterase inhibitor activity, and administration of reduced doses of heparin and protamine to minimize heparin-protamine complex formation.

Current state of surgical myocardial revascularization

Despite increasing competition from percutaneous interventions and other novel methods of non-surgical coronary revascularization, coronary artery bypass grafting (CABG) remains one of the most definitive and durable treatments for coronary artery disease, especially for those patients with extensive and diffuse disease. In recent years the CABG procedure itself has undergone innovation and evolution. This review article provides a brief historical perspective on the procedure, and examines the current state of modern variations including off-pump, limited-access, and robotic-assisted CABG.

Cerebral tumor necrosis factor alpha expression and long-term neurocognitive performance after cardiopulmonary bypass in rats

OBJECTIVE

Cerebral inflammatory reaction is discussed as a contributor to adverse cerebral outcome after cardiac surgery with cardiopulmonary bypass. This study was designed to determine the effect of cardiopulmonary bypass on both cerebral expression of tumor necrosis factor alpha and neurocognitive outcome in rats.

METHODS

With institutional review board approval, 50 rats were randomly assigned to one of 3 groups: rats of the cardiopulmonary bypass group were subjected to 75 minutes of normothermic cardiopulmonary bypass. Sham-operated animals underwent identical preparation but were not connected to cardiopulmonary bypass, whereas rats of the control group were neither anesthetized nor cannulated. Ten rats per group survived 4 hours after cardiopulmonary bypass or the sham operation for immediate postoperative determination of tumor necrosis factor alpha-expressing cells (immunohistochemistry) and cerebral tumor necrosis factor alpha mRNA levels (polymerase chain reaction). The remaining animals survived 10 days for neurocognitive assessment by using the modified hole-board test and for analysis of cerebral tumor necrosis factor alpha activation in the late postoperative period.

RESULTS

Expression of tumor necrosis factor alpha mRNA was increased 4 hours after cardiopulmonary bypass and the sham operation, with higher expression in the cardiopulmonary bypass group (chi(2) [2] = 25.08, P < .001). Both experimental groups demonstrated larger numbers of tumor necrosis factor alpha-positive cells in the early and late postoperative periods (F [1] = 13.08, P < or = .001) and an impaired neurocognitive performance on the first postoperative days compared with that seen in the control group (F [2, 24] = 4.26, P = .02).

CONCLUSIONS

Cerebral tumor necrosis factor alpha activation in both experimental groups during the early postoperative period was accompanied by transient neurocognitive impairment. Therefore cardiopulmonary bypass alone demonstrated no effect on cerebral inflammation and neurocognitive outcome.

Hepatic and renal protection during cardiac surgery

Hepatic injury in cardiac surgery is a rare complication but is associated with significant morbidity and mortality. A high index of suspicion postoperatively will lead to earlier treatment directed at eliminating or minimizing ongoing hepatic injury while preventing additional metabolic stress from ischemia, hemorrhage, or sepsis. The evidence-basis for perioperative renal risk factors remains hampered by the inconsistent definitions for renal injury. Although acute kidney injury (as defined by the Risk, Injury, Failure, Loss, End-stage criteria) has become accepted, it does not address pathogenesis and bears little relevance to cardiac surgery. Although acute renal failure requiring renal replacement therapy after cardiac surgery is rare, it has a devastating impact on morbidity and mortality, and further studies on protective strategies are essential.

Complement activation by neutrophil granulocytes

Complement plays a vital role in the body's defence systems. Cardiopulmonary bypass induces a detrimental inflammatory reaction in which the complement system is known to participate through direct effects as well as through activation of neutrophils, platelets and endothelial cells. On the other hand, it has been suggested that in the setting of cardiopulmonary bypass, complement may be activated by neutrophils, perhaps due to fragmentation caused by the heart-lung machine. We therefore investigated whether intact or fragmented neutrophils were able to activate the complement system, and whether neutrophil-platelet interaction could influence such complement activation. Lepirudin-anticoagulated plasma was incubated at 37 degrees C with resting or activated intact neutrophils or neutrophils combined with platelets, or increasing amounts of fragmented neutrophils. Complement activation was evaluated by measurement of C1rs-C1 inhibitor complexes, C4bc, C3bBbP, C3bc, C5a and sC5b-9. We found significant activation of complement only by unphysiological doses of fragmented neutrophils or supernatant from fragmented neutrophils, consistent with a limited clinical significance related to neutrophil destruction during cardiopulmonary bypass. Unstimulated neutrophils induced C3bPBb formation but little formation of other activation products, indicating an increased C3 hydrolysis which was kept under control by regulatory mechanisms. Neutrophils and platelets combined increased classical activation and decreased alternative activation, similar to the findings with platelets alone. Our data confirm that in the setting of acute neutrophil fragmentation or activation, complement activation is much more important in the inflammatory network as an event upstream to neutrophil activation than vice versa.

Impact of off-pump coronary artery bypass surgery on systemic inflammation: current best available evidence

The systemic inflammatory response after coronary artery bypass grafting using cardiopulmonary bypass (CPB) contributes substantially to postoperative organ dysfunction and coagulation disorders. Important features of this inflammatory reaction include the activation of complement and leukocytes, the release of proinflammatory cytokines, alterations in the metabolism of nitric oxide, and an increase in the production of oxygen-free radicals, which in some cases may lead to oxidant stress injury. Several strategies including the use of steroids, use of aprotinin, heparin-coated CPB circuits, and hemofiltration have been reported to reduce the inflammatory reaction induced by CPB and its consequences. A more radical and effective way of counteracting the effects of the inflammatory reaction and oxidative stress may be the omission of CPB itself. The development and application of off-pump coronary artery bypass (OPCAB) technology has largely been driven by this theme of avoiding systemic inflammatory reaction to decrease the incidence and/or severity of adverse outcomes. This review article discusses the influence of cardiopulmonary bypass on systemic inflammation and attempts to evaluate the current best available evidence on the impact of OPCAB on systemic inflammation.

Heparin anticoagulation in patients undergoing off-pump and on-pump coronary bypass surgery

PURPOSE

The authors analyzed the coagulation data of patients who underwent on-pump coronary artery bypass graft (CABG) or off-pump coronary artery bypass surgery (OPCAB) in a randomized prospective trial.

METHODS

CABG and OPCAB patients received heparin anticoagulation at 400 U x kg(-1), and 180 U x kg(-1) plus 3000 U every 30 min, respectively. In addition, OPCAB patients received a rectal aspirin, 650 mg, during the procedure. Perioperative coagulation test results (platelet count, fibrinogen, prothrombin time, partial thromboplastin time [PTT], activated clotting time [ACT], and thromboelastography [TEG; Haemoscope] were collected from CABG (n = 99) and OPCAB (n = 98) patients. Residual heparin activity after protamine was measured, using an anti-activated factor X (Xa) assay, in 10 patients from each group.

RESULTS

Our study showed that the current anticoagulation regimen in the OPCAB patients achieved a peak ACT of 445 +/- 73 s, and it preserved platelet counts and fibrinogen levels. A residual heparin effect was detected, with residual anti-Xa heparin activity of 0.2 U x ml(-1) up to 2 h after surgery in the OPCAB group. Despite the residual anticoagulation, the OPCAB group had a similar TEG index of native blood, postoperative chest tube drainage, and non-erythrocyte transfusion rate as compared with the CABG group.

CONCLUSION

We have shown that the heparin anticoagulation regimen in OPCAB patients does not lead to an immediate hypercoagulable state. Total doses of heparin and protamine were lower in the OPCAB group compared with the CABG group, and there was a residual heparin effect on TEG and PTT in the early postoperative period in the OPCAB group.

Role of amiodarone on the systemic inflammatory response induced by cardiac surgery: proinflammatory actions

PURPOSE

Amiodarone (AMIO), a widely used anti-arrhythmic drug, has been shown to reduce the incidence of atrial fibrillation after cardiac surgery and also to exert immunomodulatory actions in vitro and proinflammatory effects in vivo. The present study investigated the immunomodulatory properties of AMIO in the inflammatory response induced by cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

In this double-blind, placebo-controlled trial, 20 patients undergoing elective coronary artery bypass graft were randomized to receive placebo or AMIO 600 mg day(-1) orally for seven days before surgery and 45 mg hr(-1) intravenously for 48 hr postoperatively. Plasma levels of the proinflammatory markers C-reactive protein (CRP), fibrinogen (FBG), tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1, and the antiinflammatory marker IL-10, were compared before and after surgery.

RESULTS

Ninety-six hours after start of surgery, plasma levels of FBG had more than doubled (2.2 +/- 0.5-fold increase, P < 0.0001). Overall, FBG formation was significantly increased in the AMIO group (P = 0.048). Monocyte chemoattractant protein 1 secretion transiently increased four hours after start of surgery (6.6 +/- 4.5-fold increase) but rapidly declined thereafter, (P < 0.0001). There was a trend toward higher MCP-1 plasma concentrations in the AMIO group (P = 0.13). The plasma levels of CRP, TNF-alpha, IL-6 and Il-10 changed significantly over time, but were not altered by AMIO treatment.

CONCLUSION

In the inflammatory response induced by cardiac surgery with CPB, our data suggest that AMIO treatment is associated with a selective trend toward proinflammatory actions.

Good Recovery after Nontransthoracic Cardiopulmonary Bypass in Rats

BACKGROUND

Cardiopulmonary bypass (CPB) has been shown to be associated with systemic inflammatory response leading to postoperative organ dysfunction. Unwanted side effects of CPB are well known but poorly understood due to the absence of a stable recovery animal model that is easy to handle and reduces experiment cost and time. The purpose of this study was to establish a good recoverable rat model of CPB to study the pathophysiology of these potential complications.

MATERIALS AND METHODS

Twenty adult male Sprague-Dawley rats weighing 480 +/- 20 g were randomly divided into either the CPB group (n = 10) or the sham group (n = 10). All rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated. The blood was drained from the right atrium via the right jugular and further transferred by a miniaturized roller pump to a hollow fiber oxygenator and back to the rat via the left carotid artery. Priming consisted of 8 mL of homologous blood and 6 mL of colloid. The surface of the hollow fiber oxgenator was 0.075 m2. Rats were catheterized and brought on bypass for 120 minutes at a flow rate of 100-120 mL/kg per minute. Oxygen flow/perfusion flow was 0.8 to 1.0, and the mean arterial pressure remained 60 to 80 mmHg. Blood gas analysis, lactate dehydrogenase, and survival rate were examined subsequently.

RESULTS

All CPB rats recovered from the operative process without incident and recovery remained uneventful in follow-up at 1 week. Normal cardiac function after successful weaning was confirmed by electrocardiography and blood pressure measurements. Mean arterial pressure remained stable. The results of blood gas analysis at different times were within normal range. No significant hemolysis could be detected with the use of lactate dehydrogenase during bypass.

CONCLUSIONS

The rat model of CPB can in principle simulate the clinical setting of human CPB. The non-transthoracic model is easy to establish and is associated with excellent recovery. This reproducible model may open the field for various studies on the pathophysiological process of CPB and systemic ischemia-reperfusion injury in vivo.

The changes and effects of the plasma levels of tumor necrosis factor after coronary artery bypass surgery with cardiopulmonary bypass

BACKGROUND

Systemic inflammatory response after cardiopulmonary bypass (CPB) is thought to result from contact of cellular and humoral blood components with the synthetic material of the extracorporeal circulation system, leukocyte and endothelial activation caused by ischemia and reperfusion or endotoxins, or by surgical trauma. Proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8, play an important role in the inflammatory processes after CPB and may induce cardiac and lung dysfunction. This study examined the association of the increased release of TNF-alpha with increased myocardial and lung injury after CPB and its effect on postoperative morbidity.

METHODS

Twenty patients undergoing elective coronary artery bypass grafting (CABG) were included in the study. Four intervals of blood samples were obtaind and assayed for TNF-alpha, white blood cells, C-reactive protein, and erythrocyte sedimentation rate.

RESULTS

All patients were similar with regards to preoperative and intraoperative characteristics, and clinical outcomes were comparable. Plasma levels of TNF-alpha rose more than 20 pg/mL during and after standard CPB in 13 patients (group 1), whereas the plasma levels were less than 20 pg/mL in the remaining 7 patients (group 2) after CPB. The patients of the first group had increased mediastinal bleeding and prolonged intubation time compared to the other group.

CONCLUSION

Cardiac surgery and CPB stimulate systemic inflammatory processes characterized clinically by changes in cardiovascular and pulmonary function. Significant morbidity is rare, but most patients undergoing CPB exhibit some degree of organ dysfunction due to activation of the inflammatory response. This study showed that there were no major clinical results of TNF-alpha and white blood cell level, C-reactive protein, and erythrocyte sedimentation rate after the operation, but in patients with a high level of TNF-alpha (more than 20 pg/mL), increased mediastinal bleeding and longer orotracheal intubation time was observed. A number of studies have shown the increase of TNF-alpha after open heart surgery; however, the specific level of TNF-alpha was first described as 20 pg/mL in this study.

Gastrointestinal dysfunction following cardiac surgery

Cardiac surgery is associated with a low incidence of GI complications, but with a disproportionate mortality. A number of risk factors have become established which identify patients at risk. CPB is associated with profound reductions in mucosal blood flow. Mesenteric perfusion is altered by primary endothelial dysfunction, which may further be exacerbated by the use of vasoconstrictors during CPB; inflammatory mediators can 'prime' the mesenteric vasculature. Cardiac surgery with or without CPB is associated with increased tissue oxygen demands, particularly by the splanchnic bed. The disparity in general and regional oxygen supply and demand results in the development of mucosal hypoxia and this cannot be attributed to CPB alone. This injury is measurable by reductions in both absorptive and barrier functions of the gut. Protection may be conferred by modulating the perfusion protocol during bypass and pharmacological interventions which modify the inflammatory response to surgery.

Influence of inflammation and pump dynamic on cerebral microembolization in patients with Continuous-Flow DeBakey LVAD

Microembolic signals (MES) have shown to be associated with increased risk of ischemic stroke in patients with pulsatile left ventricular assist devices (LVADs) in contrast to continuous-flow DeBakey LVAD. The pathogenesis of microembolization in LVAD-patients is still not known. We investigated whether systemic markers of inflammation or pump dynamic correlate with cerebral microembolization in nine patients with DeBakey LVAD. We performed transcranial Doppler (TCD) for MES-detection and evaluated parameters of inflammation (i.e. Leukocytes, CRP, Fibrinogen) and pump dynamic (i.e. power, speed, flow). During a mean LVAD duration of 203.7 +/- 179 days, thromboembolic events occurred in five patients with an incidence of 0.38% (approximately 0.38 events/100 LVAD-days). We performed 290 TCD monitorings with a MES mean count of 50.4 +/- 346 signals/hour (0-5042) and prevalence of 42.8%. There was no association between individual microembolic activity and the markers of inflammation or pump dynamic. In patients with DeBakey LVAD, a high load of clinically silent cerebral microemboli can be detected. However, there is no correlation between markers of inflammation or pump dynamic and the individual amount of microembolization. We hypothesize that a gaseous nature of the majority of detected microemboli in the DeBakey LVAD may be the underlying reason for this discrepancy.

Comparison of inflammatory responses after off-pump and on-pump coronary surgery using surface modifying additives circuit

BACKGROUND

Cardiac surgery is followed by various degrees of inflammation, which have harmful consequences. Because of the central role of extracorporeal circulation (EC), off-pump coronary bypass surgery is deemed preferable. Do different modalities of EC challenge this view?

METHODS

Four groups of similar patients underwent coronary surgery: (group 1) on-pump, EC with closed surface modifying additives (SMA) circuit and no pump suckers (n = 20); (group 2) on-pump, EC with open SMA circuit and pump suckers (n = 20); (group 3) off-pump (beating heart) and heparin 3 mg/kg (n = 20); (group 4) off-pump (beating heart) and heparin 1 mg/kg (n = 20). Interleukins (IL)-6, IL-8, IL-10, myeloperoxidase, elastase, and terminal complex of the complement (TCC) were analyzed at various times: at induction (time I); after heparin (time II); after complete revascularization (time III); after protamine (time IV); and 24 hours later (time V).

RESULTS

The TCC was significantly higher in groups 1 and 2 at time III. The pattern of IL-6 was the same for the four groups. No significant difference in myeloperoxydase content was noted; however, elastase was significantly higher in the two EC (on-pump) groups.

CONCLUSIONS

Except for the complement system and elastase, on-pump surgery with SMA-coated circuits did not elicit any greater inflammatory response than off-pump surgery.