Comparison of inflammatory response during on-pump and off-pump coronary artery bypass surgery

Comparative effects of on-pump versus off-pump coronary artery bypass grafting surgery on serum cytokine and chemokine levels

Coronary artery bypass grafting (CABG) surgery with two methods (on-pump or off-pump) can be used to rescue individuals with severe coronary artery disease (CAD). Each method might cause an inflammatory response, which can lead to some complications. The aim of this study was to compare the changes in serum concentrations of IFN-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, VEGF, MCP-1, and epidermal growth factor between the two CABG surgery methods. Forty-eight patients (22 = on-pump, 26 = off-pump) who underwent on-pump or off-pump CABG surgery were enrolled in this study. Serum cytokines levels were measured in two blood samples, the first sample was taken from each patient in the morning of the day of surgery after a 12-hr fasting and the second sample on the first postoperative day at 24-hr after surgery. In baseline, comparisons between the two groups of on-pump/off-pump surgery did not show any significant difference in demographic data, anthropometric parameters, lipid profile indices, and high-sensitivity C-reactive protein levels (p > .05). There was a significant difference between the serum levels of IL-4, IL-6, IL-10, vascular endothelial growth factor (VEGF), IFN-γ, and MCP-1 in patients with on-pump surgery and a significant increase in serum IL-6 (p < .001), IL8 (p < .05), VEGF (p < .001), and IFN-γ (p < .01) levels in patients with off-pump surgery in post-operation stage compared to pre-operation. Cardiopulmonary pump in patients under CABG surgery can activate systemic inflammation and the changes of serum cytokines levels in off-pump CABG were lower compared with on-pump CABG.

A Risk Score for Predicting Long-Term Mortality Following Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

Off-pump coronary artery bypass grafting (OPCAB) comprises 15-30% of all bypass grafting surgeries. The currently available perioperative scores such as Euroscore and STS score do not specifically predict long-term mortality after off-pump procedures. The neutrophil-to-lymphocyte ratio (NLR) is one of the new, easily accessible markers of inflammation with proven predictive value in cardiovascular diseases. We aimed to develop the first risk score for long-term mortality after OPCAB and to determine if the perioperative value of NLR predicts long-term mortality in OPCAB patients.

METHODS

In total, 440 consecutive patients with multivessel stable coronary artery disease undergoing OPCAB were recruited. Differential leukocyte counts were obtained by a routine hematology analyzer. Data regarding mortality during a median follow-up time of 5.3 years were obtained from the Polish National Health Service database. An independent population of 242 patients served as a validation cohort.

RESULTS

All-cause mortality was influenced by different clinical risk factors. In multivariate regression analysis, chronic obstructive pulmonary disease, stroke history, post-operative NLR and LVEF were independent predictors of mortality. Combing all independent predictors predicted long-term all-cause mortality with 68.5% sensitivity and 71.5% specificity (AUC = 0.704, p < 0.001). After weighing these variables according to their estimates in a multivariate regression model, we developed a score to predict mortality in patients undergoing OPCAB (PREDICT-OPCAB Score, ranging from 0 to 10). Patients with a high score were at higher risk of mortality within the median 5.3 years of follow-up (score 0-3: 8.3%; 4-6: 27.0%; 7-10: 40.0%; p < 0.001 for score 0-3 vs. 4-6 and 7-10). This association was confirmed in the validation cohort.

CONCLUSIONS

We developed and validated the first simplified risk score to predict mortality following OPCAB based on easily accessible clinical factors. This risk score can be used when obtaining a patient's informed consent and as an aid in determining treatment.

Pleiotropic Effects of Acetylsalicylic Acid after Coronary Artery Bypass Grafting-Beyond Platelet Inhibition

Acetylsalicylic acid (ASA) is one of the most frequently used medications worldwide. Yet, the main indications for ASA are the atherosclerosis-based cardiovascular diseases, including coronary artery disease (CAD). Despite the increasing number of percutaneous procedures to treat CAD, coronary artery bypass grafting (CABG) remains the treatment of choice in patients with multivessel CAD and intermediate or high anatomical lesion complexity. Taking into account that CABG is a potent activator of inflammation, ASA is an important part in the postoperative therapy, not only due to ASA antiplatelet action, but also as an anti-inflammatory agent. Additional benefits of ASA after CABG include anticancerogenic, hypotensive, antiproliferative, anti-osteoporotic, and neuroprotective effects, which are especially important in patients after CABG, prone to hypertension, graft occlusion, atherosclerosis progression, and cognitive impairment. Here, we discuss the pleiotropic effects of ASA after CABG and provide insights into the mechanisms underlying the benefits of treatment with ASA, beyond platelet inhibition. Since some of ASA pleiotropic effects seem to increase the risk of bleeding, it could be considered a starting point to investigate whether the increase of the intensity of the treatment with ASA after CABG is beneficial for the CABG group of patients.

Differences of early immunological responses in on-pump versus off-pump cardiac surgery

INTRODUCTION

Cardiopulmonary bypass surgery is accompanied by an inflammatory response and pulmonary dysfunction that renders patients vulnerable to postoperative complications. The majority of studies investigating the inflammatory response in cardiopulmonary bypass focus on cytokine measurements. This study investigated the early response of peripheral blood cell types and early changes in lung tissue in on-pump versus off-pump cardiopulmonary bypass surgery.

METHODS

Landrace pigs were assigned to the following groups (n = 6 per group): 1. off-pump cardiopulmonary bypass, 2. conventional cardiopulmonary bypass, 3. heparin-coated cardiopulmonary bypass, 4. surface-reduced cardiopulmonary bypass, and 5. surface-reduced cardiopulmonary bypass plus lung perfusion. Surgery was performed under mild hyperthermia (32°C), with 90-minute ischemia and 180-minute reperfusion. Histological and flow cytometric analyses were performed.

RESULTS

Lung water content increased during reperfusion in heparin-coated (84.63 ± 2.99%) compared to conventional cardiopulmonary bypass (76.33 ± 4.56%, p = 0.04). Alveolar septal thickness increased during ischemia at heparin-coated (p < 0.01) and surface-reduced cardiopulmonary bypass plus lung perfusion (p = 0.05). Tumor necrosis factor expression increased significantly (p < 0.01) in peribronchial, perivascular, and peripheral lung areas in all on-pump groups, but not in off-pump cardiopulmonary bypass. The usage of heparin-coated cardiopulmonary bypass led to increased percentages of CD3⁺CD4⁺ (p = 0.03) and CD3⁺CD8⁺ (p = 0.01) T cells compared to an uncoated device. Natural killer and mature B lymphocytes decreased at conventional and surface-reduced cardiopulmonary bypass plus lung perfusion. Activated granulocytes and macrophages increased at conventional cardiopulmonary bypass and heparin-coated cardiopulmonary bypass.

CONCLUSION

Off-pump cardiopulmonary bypass induces less immunological response and lung injury than on-pump surgery. The reduction of cardiopulmonary bypass surface reduces the inflammatory immune response induced by cardiopulmonary bypass. Lung perfusion of surface-reduced cardiopulmonary bypass diminished the extravasation caused by surface reduction of the cardiopulmonary bypass.

Perioperative urinary thromboxane metabolites and outcome of coronary artery bypass grafting: a nested case-control study

OBJECTIVE

As a marker of in vivo thromboxane generation, high-level urinary thromboxane metabolites (TXA-M) increase the occurrence of cardiovascular events in high-risk patients. To investigate whether perioperative urinary TXA-M level is associated with major adverse cardiac and cerebrovascular events (MACCE) after coronary artery bypass graft (CABG) surgery, we designed a nested case-control study.

DESIGN

Observational, nested case-control study.

SETTING

Single-centre outcomes research in Fuwai Hospital, Beijing, China.

PARTICIPANTS

One thousand six hundred and seventy Chinese patients undergoing CABG surgery from September 2011 to October 2013.

METHODS

We obtained urinary samples from 1670 Chinese patients undergoing CABG 1 hour before surgery (pre-CABG), and 6 hours (post-CABG 6 hours) and 24 hours after surgery (post-CABG 24 hours). Patients were followed up for 1 year, and we observed 56 patients had MACCE. For each patient with MACCE, we matched three control subjects. Perioperative urinary TXA-M of the three time spots was detected in these 224 patients.

RESULTS

Post-CABG 24 hours TXA-M is significantly higher than that of patients without MACCE (11 101vs8849 pg/mg creatine, P=0.007). In addition, patients in the intermediate tertile and upper tertile of post-CABG 24 hours urinary TXA-M have a 2.2 times higher (HR 2.22, 95% CI 1.04 to 4.71, P=0.038) and a 2.8 times higher (HR 2.81, 95% CI 1.35 to 5.85, P=0.006) risk of 1 year MACCE than those in the lower tertile, respectively.

CONCLUSIONS

In conclusion, post-CABG 24 hours urinary TXA-M elevation is associated with an increase of 1 year adverse events after CABG, indicating that the induction of cyclo-oxygenase-2 by surgery-related inflammatory stimuli or platelet turnover may be responsible for the high levels of post-CABG urinary TXA-M.

TRIAL REGISTRATION NUMBER

NCT01573143.

RECCAS - REmoval of Cytokines during CArdiac Surgery: study protocol for a randomised controlled trial

Background

On-pump cardiac surgery triggers a significant postoperative systemic inflammatory response, sometimes resulting in multiple-organ dysfunction associated with poor clinical outcome. Extracorporeal cytokine elimination with a novel haemoadsorption (HA) device (CytoSorb®) promises to attenuate inflammatory response. This study primarily assesses the efficacy of intraoperative HA during cardiopulmonary bypass (CPB) to reduce the proinflammatory cytokine burden during and after on-pump cardiac surgery, and secondarily, we aim to evaluate effects on postoperative organ dysfunction and outcomes in patients at high risk.

Methods/design

This will be a single-centre randomised, two-arm, patient-blinded trial of intraoperative HA in patients undergoing on-pump cardiac surgery. Subjects will be allocated to receive either CPB with intraoperative HA or standard CPB without HA. The primary outcome is the difference in mean interleukin 6 (IL-6) serum levels between the two study groups on admission to the intensive care unit. A total number of 40 subjects was calculated as necessary to detect a clinically relevant 30 % reduction in postoperative IL-6 levels. Secondary objectives evaluate effects of HA on markers of inflammation up to 48 hours postoperatively, damage to the endothelial glycocalyx and effects on clinical scores and parameters of postoperative organ dysfunction and outcomes.

Discussion

In this pilot trial we try to assess whether intraoperative HA with CytoSorb® can relevantly reduce postoperative IL-6 levels in patients undergoing on-pump cardiac surgery. Differences in secondary outcome variables between the study groups may give rise to further studies and may lead to a better understanding of the mechanisms of haemoadsorption.

Trial registration

German Clinical Trials Register number DRKS00007928 (Date of registration 3 Aug 2015)

Acute Effect of Intravenous Administration of Magnesium Sulfate on Serum Levels of Interleukin-6 and Tumor Necrosis Factor-α in Patients Undergoing Elective Coronary Bypass Graft With Cardiopulmonary Bypass

Background:

Cardiovascular problems are among the most common health issues. A considerable number of cardiac patients undergo cardiac surgery, and coronary artery disease patients constitute about two-thirds of all these surgeries. The application of cardiopulmonary bypass (CBP) usually results in some untoward effects.

Objectives:

Studies have suggested magnesium sulfate (MgSO4) as an anti-inflammatory agent in a coronary artery bypass graft (CABG). This study aimed to assess the effect of an IV MgSO₄ infusion during elective CABG (with CBP) on the blood levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α).

Materials and Methods:

During a 12 month period, after review board approval and based on inclusion and exclusion criteria, 90 patients were selected and entered randomly into one of the two study groups (MgSO4 or placebo). Anesthesia, surgery and CBP were performed in exactly the same way, except for the use of MgSO4 or a placebo. Both preoperative and postoperative plasma levels of IL-6 and TNF-α were checked and compared between the two groups using an ELISA.

Results:

There was no difference found between the two groups with regard to; gender, basic variables, Ejection Fraction (EF), CBP time and aortic cross-clamp time. The preoperative levels of IL-6 and TNF-α were not different; however, their postoperative levels were significantly higher in the placebo group (P value = 0.01 for IL-6 and 0.005 for TNF-α).

Conclusions:

This study showed that MgSO4 infusion could suppress part of the inflammatory response after CABG with CBP. This was demonstrated by decreased levels of interleukin-6 and TNF-α in postoperative serum levels in elective CABG with CBP.

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.

Comparison of the effects of pulsatile cardiopulmonary bypass, non-pulsatile cardiopulmonary bypass and off-pump coronary artery bypass grafting on the inflammatory response and S-100beta protein

Background: We aimed to investigate the effects of off-pump coronary artery bypass grafting, pulsatile cardiopulmonary bypass, and non-pulsatile cardiopulmonary bypass techniques on the inflammatory response and the central nervous system in the current study.

Methods: A total of 32 patients who were scheduled for elective coronary artery bypass graft surgery were included in the study. The patients were allocated into three different groups according to the perfusion techniques used during the cardiopulmonary bypass procedure as follows: off-pump coronary artery bypass grafting group (n=10); pulsatile cardiopulmonary bypass group (n=11); and non-pulsatile cardiopulmonary bypass group (n=11). Serum interleukin-6, interleukin-8, tumor necrosis factor-alpha and S-100beta levels were measured preoperatively, and at 0, 6, and 24 hours postoperatively.

Results: The postoperative increase in the levels of interleukin-6 and interleukin-8 was significantly lower in the off-pump group compared to the other two groups (p<0.05), while there was no significant difference in tumor necrosis factor-alpha levels between the groups. Postoperative S-100β levels, an indicator of cerebral injury, was significantly lower in the off-pump CABG group compared to the other two groups (p<0.05).

Conclusion: We found that off-pump coronary artery bypass grafting had less negative effects on inflammatory response and central nervous system compared to pulsatile cardiopulmonary bypass and non-pulsatile cardiopulmonary bypass techniques.

Hepatocyte growth factor mobilizes non-bone marrow-derived circulating mesoangioblasts

AIMS

The identification of factors that mobilize subsets of endogenous progenitor cells may provide new therapeutic tools to enhance the repair of ischaemic tissue. We previously identified circulating mesenchymal cells that co-express endothelial markers (so-called circulating mesoangioblasts, cMABs) in children undergoing heart surgery with cardiopulmonary bypass (CPB). However, the mechanisms by which these cells are mobilized and their origin is unclear.

METHODS AND RESULTS

Circulating CD73(+)CD45(-)KDR(+) cMABs were analysed in adults undergoing heart surgery with (n = 21) or without CPB (n = 8). During surgery with CPB, cMABs are mobilized with a maximal response at the end of the operation. In contrast, off-pump heart surgery does not stimulate cMAB mobilization, indicating that the stress mediated by CPB induces the mobilization of cMAB. Circulating mesoangioblasts were enriched in blood obtained from the coronary sinus. Histologically, CD73(+) cells were detected around vessels in the heart, indicating that the heart is one of the niches of cMABs. Consistently, studies in gender mismatched bone marrow transplanted patients demonstrated that cMABs did not originate from the bone marrow. Cytokine profiling of serum samples revealed that hepatocyte growth factor (HGF) was profoundly increased at the time point of maximal mobilization of cMABs. Hepatocyte growth factor stimulated the migration of cMABs. Importantly, injection of recombinant HGF increased cMABs in rats.

CONCLUSIONS

Hepatocyte growth factor induces mobilization of non-haematopoietic progenitor cells with a cardiac repair capacity. This newly identified function together with the known pleiotrophic effects of HGF makes HGF an attractive therapeutic option for the treatment of ischaemic heart disease.