Changes of leukocyte subsets in coronary artery bypass surgery: cardiopulmonary bypass versus 'off-pump' techniques

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.

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.

Modulating Immunological Responses of Electrospun Fibers for Tissue Engineering

The promise of tissue engineering is to improve or restore functions of impaired tissues or organs. However, one of the biggest challenges to its translation to clinical applications is the lack of tissue integration and functionality. The plethora of cellular and molecular events occurring following scaffold implantation is a major bottleneck. Recent studies confirmed that inflammation is a crucial component influencing tissue regeneration. Immuno-modulation or immune-engineering has been proposed as a potential solution to overcome this key challenge in regenerative medicine. In this review, strategies to modify scaffold physicochemical properties through the use of the electrospinning technique to modulate host response and improve scaffold integration will be discussed. Electrospinning, being highly versatile allows the fabrication of ECM-mimicking scaffolds and also offers the possibility to control scaffold properties for instance, tailoring of fiber properties, chemical conjugation or physical adsorption of non-immunogenic materials on the scaffold surface, encapsulating cells or anti-inflammatory molecules within the scaffold. Such electrospun scaffold-based immune-engineering strategies can significantly improve the resulting outcomes of tissue engineering scaffolds.

The effect of oxygenator membranes on blood: a comparison of two oxygenators in open-heart surgery

Open-heart surgery (OHS) requires cardiopulmonary bypass (CPB) in most patients. Membrane oxygenators are a critical component of the CPB system. Despite advancements in CPB technology, injury to blood components during CPB still occurs and may result in complications after surgery. The purpose of the present study was to evaluate the performance of the Medtronic Affinity NT® with Trillium coating and the Cobe Optima XP® oxygenators and compare their influence on blood components.

Two hundred and fifty-six male and female patients scheduled for urgent or elective cardiac surgery with CPB were randomly assigned to either the Affinity NT or the Optima XP oxygenators. Outcomes included platelets, hemoglobin, leukocyte counts, and O2 transfer, measured preoperatively and at 15, 45 and 75 min of CPB time. Blood loss was measured at six and 12 hours postoperatively. A modified intention-to-treat analysis was conducted.

The two groups were similar for age, sex, height, weight, body surface area, and blood components at baseline. There were no differences between the Affinity NT and Optima XP for any outcome measure, although a significant change with time was seen in platelets, hemoglobin, hematocrit and leukocytes, as well as O2transfer for both groups ( p <0.001). The Affinity NT oxygenator had a significantly lower difference in pressure across the membrane ( p <0.001) compared with the Optima XP.

In conclusion, the two oxygenators performed similarly with respect to their impact on blood components, O2transfer, and blood loss postoperatively during OHS with CPB. The Affinity NT had the smaller transmembrane pressure drop of the two.

Surgical management of coronary artery disease associated with malignancy

Surgical management of patients with combined coronary artery disease and malignancy remains a challenge. In this review the time of surgical intervention, whether to treat the malignancy or the coronary artery disease first, and which bypass technique should be used during myocardial revascularization are reviewed to determine the most optimal strategy to manage patients who require coronary surgical revascularization and present with an underlying malignancy.

Off-pump versus on-pump coronary artery bypass grafting for ischaemic heart disease

BACKGROUND

Coronary artery bypass grafting (CABG) is performed both without and with cardiopulmonary bypass, referred to as off-pump and on-pump CABG respectively. However, the preferable technique is unclear.

OBJECTIVES

To assess the benefits and harms of off-pump versus on-pump CABG in patients with ischaemic heart disease.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 1, 2011), MEDLINE (OVID, 1950 to February 2011), EMBASE (OVID, 1980 to February 2011), Science Citation Index Expanded on ISI Web of Science (1970 to February 2011) and CINAHL (EBSCOhost, 1981 to February 2011) on 2 February 2011. No language restrictions were applied.

SELECTION CRITERIA

Randomised clinical trials of off-pump versus on-pump CABG irrespective of language, publication status and blinding were selected for inclusion.

DATA COLLECTION AND ANALYSIS

For statistical analysis of dichotomous data risk ratio (RR) and for continuous data mean difference (MD) with 95% confidence intervals (CI) were used. Trial sequential analysis (TSA) was used for analysis to assess the risk of random error due to sparse data and to multiple updating of accumulating data.

MAIN RESULTS

Eighty-six trials (10,716 participants) were included. Ten trials (4,950 participants) were considered to be low risk of bias. Pooled analysis of all trials showed that off-pump CABG increased all-cause mortality compared with on-pump CABG (189/5,180 (3.7%) versus 160/5144 (3.1%); RR 1.24, 95% CI 1.01 to 1.53; P =.04). In the trials at low risk of bias the effect was more pronounced (154/2,485 (6.2%) versus 113/2,465 (4.6%), RR 1.35,95% CI 1.07 to 1.70; P =.01). TSA showed that the risk of random error on the result was unlikely. Off-pump CABG resulted in fewer distal anastomoses (MD -0.28; 95% CI -0.40 to -0.16, P <.00001). No significant differences in myocardial infarction, stroke, renal insufficiency, or coronary re-intervention were observed. Off-pump CABG reduced post-operative atrial fibrillation compared with on-pump CABG, however, in trials at low risk of bias, the estimated effect was not significantly different.

AUTHORS' CONCLUSIONS

Our systematic review did not demonstrate any significant benefit of off-pump compared with on-pump CABG regarding mortality, stroke, or myocardial infarction. In contrast, we observed better long-term survival in the group of patients undergoing on-pump CABG with the use of cardiopulmonary bypass and cardioplegic arrest. Based on the current evidence, on-pump CABG should continue to be the standard surgical treatment. However, off-pump CABG may be acceptable when there are contraindications for cannulation of the aorta and cardiopulmonary bypass. Further randomised clinical trials should address the optimal treatment in such patients.

Modulation of the cellular and humoral immune response to pediatric open heart surgery by methylprednisolone

BACKGROUND

With the intention to reduce overshooting immune response, glucocorticoids are frequently administered perioperatively in children undergoing open heart surgery. In a retrospective study we investigated extensively the modulation of the humoral and cellular immune response by methylprednisolone (MP).

METHODS

This study was carried out on blood samples from two groups of children who had undergone surgical correction of atrial or ventricular septal defects, either without (MP⁻, n = 10), or with MP administration (MP+, n = 23, dose median 11 (IQR 10-16) mg kg⁻¹ body weight) before cardiopulmonary bypass (CPB, duration median 42 (IQR 36-65) min). EDTA blood was obtained 24 h preoperatively, after anesthesia, at CPB begin and end, 4, 24, and 48 h after surgery, at discharge and at out-patient follow-up (median 8.2 (IQR 3.3-12.2) months after surgery). Complex blood analysis including clinical chemistry and flow cytometry were performed to monitor humoral immune response, differential blood count, lymphocyte subsets, and the degree of activation of various leukocyte subpopulations.

RESULTS

The patients' postoperative courses and follow-up were uneventful. Release of IL-6 and IL8 was reduced and that of the anti-inflammatory cytokine IL-10 upregulated by MP. Significant increase of circulating neutrophils and monocytes as inflammatory reaction to surgery and CPB contact was detected in both groups. However, invasion of monocytes to the periphery was delayed with MP. CD4+ and CD8+ T-lymphocyte counts were lower with MP treatment. B-lymphocyte count increased significantly after surgery in MP+ but remained constant in MP⁻ group.

CONCLUSIONS

MP treatment partially decreased the pro-inflammatory effect of CPB surgery and induced anti-inflammatory effect on the cellular and humoral level.

Influence of cardiopulmonary resuscitation on levels of tumour markers

Tumour markers (TM), including alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), cancer antigen (CA) 15-3 and prostate-specific antigen (PSA), are serum markers for malignant diseases. Previous studies investigating the effect of acute and chronic inflammation, cardiopulmonary bypass surgery and cardiopulmonary resuscitation (CPR) on levels of TM showed conflicting results. Cardiopulmonary resuscitation (CPR) may result in a profound inflammatory response, and is frequently associated with severe tissue hypoperfusion. The present study investigated whether AFP, CEA, CA 15-3 and PSA are influenced by CPR. Alpha-fetoprotein (AFP), CEA, CA 15-3 and PSA (only in male patients) were assessed immediately after hospital admission, 6 h, 12 h and 2 days after prolonged CPR in eight male and 12 female patients. Serum levels of AFP, CEA, CA 15-3 did not change significantly after CPR. Prostate-specific antigen (PSA) levels increased significantly with a highest level in the study period 48 h after CPR (3.3 +/- 3.1 and 28.3 +/- 30.5 ng/mL for baseline and 48 h levels, respectively; P < 0.001). Alpha-fetoprotein (AFP), CEA, CA 15-3 and PSA (in men) values above the normal range were observed in 0%, 13.8%, 3.8% and 46.9% of all measurements respectively. At least one value above the normal range were observed in 0%, 20%, 5% and 75% of all patients for AFP, CEA, CA 15-3 and PSA (in men) respectively. Baseline values of AFP, CEA, CA 15-3 and PSA (in men) were above the normal range in 0%, 15%, 5% and 10% of all patients respectively. Levels for all markers did not differ significantly between survivors and non-survivors. In conclusion, prolonged CPR does not influence AFP, CEA, CA 15-3 serum levels, but is frequently associated with increases of PSA. Thus, in contrast to PSA, interpretation of AFP, CEA, CA 15-3 serum levels is not influenced by recent CPR.

In Vitro Restoration of Post-Operatively Decreased IFN-Gamma Levels After Cardiac Surgery and Its Effect on Pro- and Anti-Inflammatory Mediators

BACKGROUND

A decreased synthesis of interferon gamma (IFN-gamma) by TH 1 lymphocytes after cardiac operations with cardiopulmonary bypass (CPB) is part of the inflammatory response to local operative and systemic traumas. The consequences of this mechanism on the release of pro- and anti-inflammatory cytokines remain unclear. To evaluate the role of IFN-gamma, we added recombinant IFN-gamma to peripheral blood mononuclear cells (PBMCs) on the first post-operative day in an attempt to restore pre-operative values and then measured the release of pro- and anti-inflammatory cytokines in vitro.

METHODS

PBMCs of 10 patients scheduled for elective coronary artery bypass grafting (CABG) were obtained pre-operatively (d0) and on the first (d1) and third (d3) post-operative days. The release of IL-6, IL-8, TNF-alpha, IFN-gamma, IL-10, IL-2, and IL-4 was studied after stimulation (48 h) with PHA (phytohemagglutinin) and LPS (lipopolysaccharide) in the absence or presence of recombinant human IFN-gamma.

RESULTS

Endogenous IFN-gamma synthesis was suppressed on d1. Adding exogenous IFN-gamma restored IFN-gamma levels to normal on d1 and doubled IFN-gamma levels on d0 and d3. The addition of IFN-gamma increased TNF-alpha levels up to 250% on d1 and IL-2 synthesis by 75% on d1 and d3; the IL-2 levels, however, were still significantly depressed. The addition of recombinant IFN-gamma did not affect the synthesis of IL-6, IL-8, IL-10, and IL-4.

CONCLUSIONS

Contrary to our expectations, the in vitro release of IL-6 and IL-8 as well as IL-10 and IL-4 was not influenced by the addition of IFN-gamma. However, TNF-alpha production in isolated PBMC cultures increased significantly on the first post-operative day. This may indicate a hyper-reactivity of PBMCs to IFN-gamma and suggests that the decrease in IFN-gamma synthesis might prevent an excessive stimulation of the non-specific immune system by high TNF-alpha levels after cardiac surgery.

Is Interferon Gamma Suppression After Cardiac Surgery Caused by a Decreased Interleukin-12 Synthesis?

BACKGROUND

The suppression of interferon gamma (IFN-gamma) synthesis after cardiac surgery is discussed as a cause of postoperative immunosuppression that predisposes to postoperative infectious complications. Because several studies have suggested that interleukin-12 (IL-12) production by monocytes and macrophages is reduced after cardiac surgery, this might cause a decrease in IFN-gamma release. To better understand these processes, we assessed the role of IL-12 in IFN-gamma synthesis in vitro before and after cardiac surgery.

METHODS

Heparinized whole blood samples were obtained from 20 patients undergoing elective cardiac surgery preoperatively (day 0) and on the first (day 1), third (day 3), and fifth (day 5) postoperative days, and stimulated (24 hours) with staphylococcal enterotoxin B and lipopolysaccharide. Recombinant IL-12 was added at each time point investigated. Interferon-gamma, IL-12, IL-2, IL-4, and IL-5 concentrations and histocompatibility leukocyte antigen-DR (HLA-DR) expression on monocytes and macrophages were assayed by flow cytometry.

RESULTS

The HLA-DR expression, IL-12 release, and IFN-gamma synthesis were significantly reduced on day 1, day 3, and day 5. Recovery began on day 3. Interleukin-12 caused a significant increase in IFN-gamma synthesis at each time point. When IL-12 was added, IFN-gamma synthesis returned to preoperative levels on days 3 and 5.

CONCLUSIONS

The synthesis of IFN-gamma is significantly reduced after cardiac surgery. The application of IL-12 causes an increase in IFN-gamma synthesis before surgery and a return of IFN-gamma to preoperative levels within a few days after surgery. These findings suggest that postoperative suppression of IFN-gamma release is caused by a decrease in IL-12 synthesis. In addition, IL-12 has a mainly proinflammatory effect both before and after surgery.

Postoperative white blood cell count predicts atrial fibrillation after cardiac surgery

BACKGROUND

Postoperative atrial fibrillation (AF) occurs in as many as 50% of cardiac surgery patients and represents the most common postoperative rhythm complication. The cause of AF after cardiac surgery is incompletely understood, and its prevention remains suboptimal. Currently the role of inflammation and oxidative stress on electrical remodeling is under investigation, and recent studies have demonstrated that C-reactive protein levels are elevated in AF. The purpose of the present study was to investigate the correlation between the postoperative white blood cell (WBC) count as a marker of inflammation and the development of postoperative AF after cardiac surgery.

METHODS AND RESULTS

Patients undergoing elective cardiac surgery in the absence of significant left ventricular dysfunction (n = 253; average age, 65 +/- 11 years) were recruited to the present prospective study. Atrial fibrillation developed during the postoperative period in 99 patients (39.1%) of the total study population. The WBC count was prospectively assessed in all patients to determine the predictive value of baseline and postoperative WBC count on development of postoperative AF. Baseline WBC count was 6.8 +/- 1.9 x 10(9)/L and 6.8 +/- 2.2 x 10(9)/L (p = 0.95), respectively, in patients with and without postoperative AF; and postoperative peak WBC count was 16.3 +/- 6.5 x 10(9)/L and 15 +/- 4.2 x 10(9)/L (p = 0.048), respectively, in patients without postoperative AF. However, neither baseline nor peak monocyte count differed significantly among patients with and without postoperative AF: 0.43 +/- 0.15 x 10(9)/L and 0.46 +/- 0.46 x 10(9)/L (p = 0.5), and 0.91 +/- 0.3 x 10(9)/L and 0.93 +/- 0.4 x 10(9)/L (p = 0.8), respectively. In addition to a more pronounced increase in peak WBC count (above v below median; odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1-2.7; p < 0.05), increasing age (above v below median; OR, 2.6; CI, 1.2-3.9; p < 0.01), surgery for valvular heart disease versus coronary artery bypass grafting (OR, 2.8; CI, 1.1-3.5; p < 0.01), development of postoperative complications, such as stroke, infections, or unstable hemodynamics (OR, 1.9; CI, 1.0-7.5; p < 0.05), and perioperative nonuse of beta-adrenergic blockers (OR, 1.7; CI, 1.1-4.9; p < 0.05) were identified as independent predictors of postoperative AF by multivariate logistic regression analysis.

CONCLUSIONS

Cardiac surgery is associated with an elevated postoperative WBC count that represents a common marker of inflammation. A more pronounced increase in postoperative WBC count independently predicts development of postoperative AF. These data provide additional evidence to support the association between the inflammatory response and postoperative AF.

Expression of CD97 and Adhesion Molecules on Circulating Leukocytes in Patients Undergoing Coronary Artery Bypass Surgery

OBJECTIVE

Leukocyte activation is thought to be responsible for the adverse effects and postoperative complications following cardiopulmonary bypass (CPB). A novel cell surface molecule, CD97, is a sensitive marker of leukocyte and primary lymphocyte activation. The present study aimed to determine the activation of different leukocyte subsets by comparing the expression of CD97 and adhesion molecules (CD11, CD18) in patients receiving coronary surgery with or without CPB.

METHODS

30 patients were enrolled and scheduled for coronary bypass surgery under CPB (20 patients, group A) and with off-pump (OP) operation (10 patients, group B). Blood samples were taken before and during surgery, and over the following first week.

RESULTS

Here, we report an early decrease in CD97 expression of granulocytes (PMN) and monocytes (MC) followed by an intensive increase reaching the maximum on postoperative days 2 and 3 in patients operated with CPB. The rate of active CD97-positive lymphocytes showed a marked, gradual increase until postoperative day 3 and remained elevated up to day 7 after CPB. OP surgery resulted in moderate alteration in the presence of CD97 on PMN, MC and lymphocytes. The expression of adhesion molecules was similar to CD97 in all leukocyte subsets.

CONCLUSION

The findings about CD97 expression suggest considerable leukocyte activation following coronary bypass with CPB compared to OP surgery. The collected data show that the lymphocytes are highly activated and involved in leukocyte sequestration after CPB. Moreover, the importance of CD97 in CPB-related inflammatory response can be stated.

Off-pump coronary artery bypass grafting does not reduce lymphocyte activation

OBJECTIVE

In this study, we test the hypothesis that off-pump coronary bypass surgery might result in less lymphocyte activation than on-pump coronary surgery. We also study the behavior of lymphocyte activation markers during and after surgery.

BACKGROUND

Coronary artery bypass surgery is known to be associated with changes of inflammatory mediators, immune function, and early phase lymphocyte activation, which could cause postoperative lymphopenia and lymphocyte unresponsiveness.

METHODS

We studied lymphocyte activation response in 28 patients randomized to off-pump (n = 13) or on-pump (n = 15) coronary artery bypass surgery. Expression of CD25, CD26, CD69, and DR on T (CD3+) and B (CD19+) lymphocytes on peripheral blood was assessed through flow cytometry.

RESULTS

The response of T lymphocytes and their activation markers, as well as B lymphocytes and their activation markers, was similar after on- and off-pump surgery. Overall, T lymphocytes decreased to the lowest level 9 h after surgery and tended to increase later. For B lymphocytes, there was early reduction with increase on the 1st postoperative day. There was early activation of CD69+ and late activation of CD25+ on T lymphocytes. For B lymphocytes, there was early activation of CD69+ and late activation of DR+.

CONCLUSIONS

(1) Compared to on-pump cardiopulmonary bypass, off-pump surgery does not reduce lymphocyte activation. (2) Coronary bypass surgery causes the early activation of lymphocytes, as evidenced by the increased expression of lymphocyte activation markers.

Side Effects of Cardiopulmonary Bypass:. What Is the Reality?

Despite many years of clinical and experimental research, the contribution of cardiopulmonary bypass (CPB) and cardioplegic arrest to morbidity and mortality following cardiac surgery remains unclear. This is due, in part, to lack of suitable control group against which bypass and cardioplegic arrest can be compared. The recent success of beating heart coronary artery bypass grafting has, however, for the first time, provided an opportunity to compare the same operation, in similar patient groups, with, or without CPB and cardioplegic arrest. CPB is associated with an acute phase reaction of protease cascades, leucocyte, and platelet activation that result in tissue injury. This is largely manifest as subclinical organ dysfunction that produces a clinical effect in those patients that generate an excessive inflammatory response or in those with limited functional reserve. The contribution of myocardial ischemia/reperfusion, secondary to aortic cross-clamping, and cardioplegic arrest, to the systemic inflammatory response and wider organ dysfunction is unknown, and requires further evaluation in clinical trials.

Impact of cardiac surgery using cardiopulmonary bypass on course of chronic lymphatic leukemia: a case-control study

BACKGROUND

Chronic lymphatic leukemia (CLL) is a common disease among elderly individuals. The number of older patients undergoing operations with cardiopulmonary bypass (CPB) is increasing. The aim of the present study was to evaluate the impact of cardiac surgery using CPB on the long-term course of CLL.

METHODS

From 1992 to 2000, a total of 28 patients with CLL underwent heart surgery using CPB at our institution (group I). These patients were compared with 25 patients from the CLL register who were retrospectively matched with regard to preoperative administration of chemotherapy, Binet classification, age, and sex (group II). A time-point was selected for each patient in group II so that the variables for the two groups corresponded in relation to the time of operation of the patients in group I. Midterm follow-up data in both groups were analyzed.

RESULTS

There were no differences between groups regarding matched variables. The mean follow-up time was similar in both groups (2.6 +/- 2.2 vs 2.3 +/- 1.3 years, p > 0.5). The 30-day mortality in group I was 14.3%. The mean stay in the intensive care unit was 4.2 +/- 7.5 days; the median number of units of packed red blood cells transfused was three (range 0 to 17). Compared with group II, in group I significantly fewer patients (11 vs 17, p = 0.049) required chemotherapy significantly later (1.98 +/- 2.06 vs 0.84 +/- 1.18 years, p = 0.018). During follow-up, no difference was found between groups regarding severe infections (10 vs 14, p = 0.14). Despite postoperative mortality in group I, the long-term mortality was similar in both groups (p = 0.3).

CONCLUSIONS

Cardiac surgery using CPB did not have a negative impact on the natural course of CLL. Moreover, this procedure seems to be associated with a decrease in the number of postoperative chemotherapy administrations and with an increase of chemotherapy-free survival time. Although CLL may be a risk factor in the early postoperative period, it is not a contraindication for cardiac surgery using CPB.

Proinflammatory and antiinflammatory cytokines after cardiac operation: different cellular sources at different times

BACKGROUND

Cardiac operation produces substantial alterations within the immune system, which possibly predispose postoperative complications. However, the interplay between proinflammatory and antiinflammatory reactions and the cells involved in this process are not completely clear. Therefore, we investigated serum levels, as well as synthesis patterns, of proinflammatory and antiinflammatory cytokines.

METHODS

Serum levels and production of interleukin (IL) IL-5, IL-6, IL-10, tumor necrosis factor-alpha, and interferon-gamma, using a mixed cell culture, (ie, monocytes, macrophages, and lymphocytes), as well as a purified lymphocyte culture were measured preoperatively (day 0), on postoperative day 1, on postoperative day 3, and on postoperative day 5 in 25 patients undergoing cardiac operations and were compared with 10 healthy volunteers.

RESULTS

Serum level and mixed cell culture, production of IL-6, tumor necrosis factor-alpha, and IL-10 increased on postoperative day 1, but decreased in lymphocyte culture. Base line values were reached on postoperative day 5. Interferon-gamma serum levels remained unchanged, whereas IL-5 serum levels increased on postoperative days 3 and 5. Cell culture synthesis showed a significant suppression for both mediators in both cell cultures, which returned to baseline on postoperative day 3 in mixed cell culture. Interferon-gamma production by lymphocytes was suppressed until postoperative day 5, whereas IL-5 returned to preoperative values on postoperative day 5.

CONCLUSIONS

Cardiac operation induces a biphasic immune response. The first phase (postoperative day 1) appears to represent the proinflammatory and antiinflammatory reaction of the innate immune system returning to base line on postoperative day 3. The second phase (postoperative day 5) may represent the response of the adaptive immune system and is characterized by an antiinflammatory type of reaction. This may explain why the systemic inflammatory response occurs immediately after cardiac operation, whereas infections occur later.

Inter-individual differences in cytokine release in patients undergoing cardiac surgery with cardiopulmonary bypass

Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response with secretion of cytokines (e.g. IL-6, TNF-alpha, IL-1 beta and sIL-2R). The objective of the following study was to investigate in vitro and in vivo cytokine responses and white blood cell counts (WBC) of patients with high versus low cytokine secretion after a coronary artery bypass grafting (CABG) procedure. Twenty male patients undergoing elective CABG surgery with CPB under general anaesthesia were enrolled in the study. On the day of surgery (postoperatively), serum levels of TNF-alpha and IL-1 beta were significantly higher in patients of the high IL-6 level group compared to the respective values in the patient group with low IL-6 levels. The inter-individual differences in IL-6 release in patients undergoing CABG surgery with CPB were accompanied by differences in the release of other cytokines, such as TNF-alpha, IL-1 beta and sIL-2R. To understand whether genetic background plays a role in influencing cytokine plasma levels under surgical stress, we examined the distribution of polymorphic elements within the promoter regions of the TNF-alpha and IL-6 genes, and determined their genotype regarding the BAT2 gene and TNF-beta intron polymorphisms. Our preliminary data suggests that regulatory polymorphisms in or near the TNF locus, more precisely the allele set 140/150 of the BAT2 microsatellite marker combined with the G allele at -308 of the TNF-alpha gene, could be one of the genetic constructions providing for a less sensitive response to various stimuli. Our results suggest: (1) close relationships between cytokine release in the postoperative period, and (2) inter-individually varying patterns of cytokine release in patients undergoing CABG surgery with CPB.

Con: beating-heart surgery for coronary revascularization: is it the most important development since the introduction of the heart-lung machine?

Contrary to what the media tend to suggest, beating-heart coronary artery bypass grafting (BHCABG) is not a new technique. It has been performed since the advent of coronary revascularization but, until recently, was largely abandoned in favor of cardiopulmonary bypass (CPB) and cardioplegic techniques. However, with the introduction of minimally invasive coronary surgery and mechanical methods for target-artery stabilization, interest in BHCABG has been renewed. In carefully selected cases, this approach has the advantages of simplicity, avoidance of the inflammatory response caused by CPB, and a decreased need for blood transfusion. Nevertheless, BHCABG may be technically difficult in some patients, and it involves a steep learning curve. Potential risks include incomplete revascularization, ischemia during temporary target-artery occlusion, and suboptimal anastomoses. Because of the need for special equipment, BHCABG can be expensive and time consuming. It may benefit older or sicker patients who are poor candidates for CPB, especially those with left anterior descending or right coronary artery lesions, but it should be used with discretion and not be considered for all coronary patients.