Clinical evaluation of leukocyte-depleted blood cardioplegia for pediatric open heart operation

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

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

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

OBJECTIVES

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

DESIGN

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

SETTING

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

PARTICIPANTS

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

INTERVENTIONS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Leucocyte filtration of residual heart-lung machine blood in children undergoing congenital heart surgery

Cardiopulmonary bypass (CPB) leads to a generalized inflammatory reaction, resulting in increased postoperative leucocyte counts and decreased pulmonary function. In adults, removal of leucocytes from the residual heart - lung machine blood after CPB improved postoperative oxygenation. In children, however, the clinical effects of leucocyte filtration of the residual heart - lung machine blood are unknown. Therefore, we measured postoperative leucocyte counts and arterial blood oxygenation in children undergoing congenital cardiac surgery in a randomized prospective study. Anaesthesia and CPB were standardized. After CPB, the residual heart-lung machine blood was collected as usual. In a group of 25 children, this blood was filtered with a leucocyte depletion filter before transfusion. A control group of 25 children received this blood unfiltered. We found that the postoperative leucocyte counts were significantly lower in the filter group than in the control group ( p=0.02, repeated measurements ANOVA). This difference reached a maximum on the second postoperative day (12.9×109/L filter versus 15.9×109/L control, p=0.02, Student’s t-test). Values for the arterial blood oxygenation on the first postoperative day were not different between the two groups (15.5±1 kPa filter versus 14.6±1.3 kPa control, p=0.57, Student’s t-test). We conclude that leucocyte filtration of the residual heart-lung machine blood reduced systemic leucocyte counts, but did not improve arterial blood oxygenation in children after congenital heart surgery.

Leucocyte-depleted Blood Cardioplegia

The effect of the depletion of leucocytes from cardioplegic and initial myocardial reperfusion blood on the inflammatory response and myocardial protection in patients with unstable angina undergoing cardiopulmonary bypass (CPB) was studied. Patients were allocated randomly to a leucocyte-depleted (LD) group or a control group. The LD group received continuous retrograde LD isothermic blood cardioplegia and the control group received isothermic blood cardioplegia. Blood samples were collected at seven time-points before, during and after the procedure. Total leucocyte counts of cardioplegia blood in the LD group were significantly lower than in the control group, but systemic leucocyte and neutrophil counts after CPB did not differ between the groups. The levels of adhesion molecules, cytokines, elastase and malondialdehyde were significantly increased after CPB in both groups and reached peak values 2-6 h after surgery; no other significant differences were found. LD cardioplegia and myocardial reperfusion did not attenuate the endothelial and neutrophil-mediated components of the CPB-induced inflammatory response, which may lead to myocardial reperfusion injury.

Leukoreduction for the prevention of adverse reactions from allogeneic blood transfusion

BACKGROUND

A blood transfusion is an acute intervention, implemented to solve life and health-threatening conditions on a short-term basis. However, blood transfusions have adverse events, some of them potentially related to immune modulation or to a direct transmission of infectious agents (e.g. cytomegalovirus). Leukoreduction is a process in which the white blood cells are intentionally reduced in packed red blood cells (PRBCs) in order to reduce the risk of adverse reactions. The potential benefits of leukoreduced PRBCs in all types of transfused patients for decreasing infectious and non-infectious complications remain unclear.

OBJECTIVES

To determine the clinical effectiveness of leukoreduction of packed red blood cells for preventing adverse reactions following allogeneic blood transfusion.

SEARCH METHODS

We ran the most recent search on 10th November 2015. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library), MEDLINE (OvidSP), Embase(OvidSP), CINAHL Plus (EBSCO), LILACS (BIREME), and clinical trials registers. In addition, we checked the reference lists of all relevant trials and reviews identified in the literature searches.

SELECTION CRITERIA

Randomised clinical trials including patients of all ages requiring PRBC allogeneic transfusion. Any study was eligible for inclusion, regardless of the length of participant follow-up or country where the study was performed. The primary outcome was transfusion-related acute lung injury (TRALI). Secondary outcomes were death from any cause, infection from any cause, non-infectious complications and any other adverse event.

DATA COLLECTION AND ANALYSIS

At least two review authors independently performed study selection, 'Risk of bias' assessments and data extraction. We estimated pooled relative risk for dichotomous outcomes, and we measured statistical heterogeneity using I² statistic. The random-effects model was used to synthesise results. We conducted a trial sequential analysis to assess the risk of random errors in cumulative meta-analyses.

MAIN RESULTS

Thirteen studies, most including adult patients, met the eligibility criteria. We found no clear evidence of an effect of leukoreduced PRBC versus non-leukoreduced PRBC in patients that were randomised to receive transfusion for the following outcomes: TRALI: RR 0.96, 95% CI 0.67 to 1.36, P = 0.80 from one trial reporting data on 1864 trauma patients. The accrued information of 1864 participants constituted only 28.5% of the diversity-adjusted required information size (DARIS) of 6548 participants. The quality of evidence was low. Death from any cause: RR 0.81, 95% CI 0.58 to 1.12, I² statistic = 63%, P = 0.20 from nine trials reporting data on 6485 cardiovascular surgical patients, gastro-oncology surgical patients, trauma patients and HIV infected patients. The accrued information of 6485 participants constituted only 55.3% of the DARIS of 11,735 participants. The quality of evidence was very low. Infection from any cause: RR 0.80, 95% CI 0.62 to 1.03, I² statistic = 84%, P = 0.08 from 10 trials reporting data on 6709 cardiovascular surgical patients, gastro-oncology surgical patients, trauma patients and HIV infected patients. The accrued information of 6709 participants constituted only 60.6% of the DARIS of 11,062 participants. The quality of evidence was very low. Adverse events: The only adverse event reported as an adverse event was fever (RR 0.81, 95% CI 0.64 to 1.02; I² statistic= 0%, P = 0.07). Fever was reported in two trials on 634 cardiovascular surgical and gastro-oncology surgical patients. The accrued information of 634 participants constituted only 84.4% of the DARIS of 751 participants. The quality of evidence was low. Incidence of other non-infectious complications: This outcome was not assessed in any included trial.

AUTHORS' CONCLUSIONS

There is no clear evidence for supporting or rejecting the routine use of leukoreduction in all patients requiring PRBC transfusion for preventing TRALI, death, infection, non-infectious complications and other adverse events. As the quality of evidence is very low to low, more evidence is needed before a definitive conclusion can be drawn.

Cardioprotective potential of annexin-A1 mimetics in myocardial infarction

Myocardial infarction (MI) and its resultant heart failure remains a major cause of death in the world. The current treatments for patients with MI are revascularization with thrombolytic agents or interventional procedures. These treatments have focused on restoring blood flow to the ischemic tissue to prevent tissue necrosis and preserve organ function. The restoration of blood flow after a period of ischemia, however, may elicit further myocardial damage, called reperfusion injury. Pharmacological interventions, such as antioxidant and Ca(2+) channel blockers, have shown premises in experimental settings; however, clinical studies have shown limited success. Thus, there is a need for the development of novel therapies to treat reperfusion injury. The therapeutic potential of glucocorticoid-regulated anti-inflammatory mediator annexin-A1 (ANX-A1) has recently been recognized in a range of systemic inflammatory disorders. ANX-A1 binds to and activates the family of formyl peptide receptors (G protein-coupled receptor family) to inhibit neutrophil activation, migration and infiltration. Until recently, studies on the cardioprotective actions of ANX-A1 and its peptide mimetics (Ac2-26, CGEN-855A) have largely focused on its anti-inflammatory effects as a mechanism of preserving myocardial viability following I-R injury. Our laboratory provided the first evidence of the direct protective action of ANX-A1 on myocardium, independent of inflammatory cells in vitro. We now review the potential for ANX-A1 based therapeutics to be seen as a "triple shield" therapy against myocardial I-R injury, limiting neutrophil infiltration and preserving both cardiomyocyte viability and contractile function. This novel therapy may thus represent a valuable clinical approach to improve outcome after MI.

Does leukocyte-depleted blood cardioplegia reduce myocardial reperfusion injury in cardiac surgery? A systematic review and meta-analysis

Blood cardioplegia in cardiac surgery contains leukocytes, which causes the inflammatory reaction and promotes myocardial reperfusion injury. The removal of leukocytes from the cardioplegia line, using specialized filters, has been proposed as one of the effective methods in attenuating the inflammatory response. We performed a two-level search to identify randomized, controlled trials concerning the effects of leukocyte-depleted blood cardioplegia on myocardial reperfusion injury. Sixteen studies, comprising 738 patients, met the selection criteria. There are significant reductions in creatinine kinase isoenzyme MB (CK-MB) during 4-8h postoperatively (SMD - 0.577; 95% CI -0.795 to -0.358; p=0.000), CK-MB peak (SMD - 0.713; 95% CI -1.027 to -0.400; p=0.000), troponin in the period of 4-8h postoperatively (SMD - 0.502; 95% CI -0.935 to -0.069; p=0.023), troponin peak (SMD - 0.826; 95% CI -1.373 to -0.279; p=0.003) and inotropic support (RR, 0.500; 95% CI 0.269 to 0.931; p=0.029). Leukocyte-depleted blood cardioplegia may reduce myocardial reperfusion injury in the early postoperative period, but there has been no evidence to support the clinically significant difference. Larger and more precise randomized control trials are needed to further elucidate the cardioprotective effects of cardioplegia leukofiltration.

Continuous perfusion of donor hearts with oxygenated blood cardioplegia improves graft function

Donor hearts cannot be preserved beyond 6h using cold storage (CS). Improving preservation methods may permit prolonged storage of donor heart. We compared graft function in large animal model after prolonged preservation (8h) using continuous perfusion (CP) and CS method. Twenty-four miniature pigs were used as donors and recipients. Donor hearts were either stored in University of Wisconsin solution (UW solution) for 8h at 0-4°C (CS group, n=6) or were continuously perfused with oxygenated blood cardioplegia at 26°C for 8h (CP group, n=6). After preservation, hearts were transplanted into recipients and reperfused for 3h. Left ventricular (LV) function, cardiac output (CO), malondialdehyde (MDA) and adenosine triphosphate (ATP) levels, and water content were measured. Although water content of CP hearts was higher than that of CS, LV contractility and diastolic function of CP hearts were superior to those of CS. In addition, CP hearts performed better than CS hearts on CO in working heart state. ATP was better preserved and MDA levels were lower in CP hearts compared with those of CS (P<0.0001). Donor hearts can be preserved longer using continuous perfusion with oxygenated blood cardioplegia and this method prevents time-dependent ischemic injury.

What is the Role of Leukocyte Depletion in Cardiac Surgery?

Leukocytes play an important pathogenic role in ischaemia-reperfusion injury. During cardiopulmonary bypass, leukocyte filters have the potential to remove leukocytes, thereby reducing contact of activated leukocytes with the endothelium of target organs. Improvement in the safety and efficacy of commercially available leukocyte filters in recent years has led to their increasing use in cardiac surgery. However, the benefits have been inconsistent. Current evidence suggests that leukocyte depletion may not have a significant impact in low risk elective coronary artery bypass grafting but may be beneficial in valve surgery and high-risk cardiac surgery. High-risk surgical groups that may benefit from leukocyte filtration are those with left ventricular hypertrophy (LV mass>300 g), poor ejection fraction (EF<40%), chronic obstructive airways disease (predicted FEV1<75%), prolonged ischaemia (cross clamp time>120 min or cardiac transplantation), paediatric cardiac surgery and patients in cardiogenic shock requiring emergency coronary artery bypass grafting. Future trials should be powered to detect important clinical end points and be designed to avoid premature exhaustion of the filter.

The effects of various leukocyte filtration strategies in cardiac surgery

It is known that cardiopulmonary bypass causes an inflammatory reaction with an associated morbidity and mortality. Several anti-inflammatory strategies have been implemented to reduce this response, including leukocyte removal from the circulation using specialised filters. The aim of this study is to systematically review the available evidence on leukocyte filtration in cardiac surgery, focusing on its effect on systemic inflammation and whether this has influenced clinical outcomes. Five electronic databases were systematically searched for studies reporting the effect of leukocyte filtration at any point within the cardiopulmonary bypass circuit in humans. Reference lists of all identified studies were checked for any missing publications. Two authors independently extracted the data from the included studies. Whilst systemic leukodepleting filters do not appear to consistently lower leukocyte counts, they may preferentially remove activated leukocytes. Small improvements in early post-operative lung function in patients receiving systemic leukodepletion have been reported, but this does not lead to reduced hospital stay or decreased mortality. There is substantial evidence that cardioplegic leukocyte filtration attenuates the reperfusion injury at a cellular level, but this has not been translated into clinical improvements. Finally, whilst various strategies involving multiple leukocyte filters, or the incorporation of pharmacological agents into leukocyte-depleting protocols have been evaluated, the current available results are not conclusive. Our study suggests that there is not enough high quality or consistent evidence to draw guidelines regarding the use of leukocyte-depleting filters within routine cardiac surgical practice.

Leukocyte-depleted terminal blood cardioplegia provides superior myocardial protective effects in association with myocardium-derived nitric oxide and peroxynitrite production for patients undergoing prolonged aortic crossclamping for more than 120 minutes

OBJECTIVES

This study was designed to examine the myocardial protective effect of leukocyte-depleted terminal blood cardioplegia in association with nitric oxide and peroxynitrite production, especially for patients undergoing prolonged aortic crossclamping.

METHODS

Fifty-four patients (34 men, 20 women, mean age 56.7 +/- 12.7 years) undergoing aortic valve replacement were randomly allocated to one of two groups; group LDTC (n = 27) received 10 minutes of leukocyte-depleted terminal blood cardioplegic solution, and group CONT (n = 27) served as controls. Each group was subdivided into 2 groups: aortic crossclamping for less than 120 minutes in groups LDTC-S (n = 13) and CONT-S (n = 14); aortic crossclamping for 120 minutes or more in groups LDTC-L (n = 14) and CONT-L (n = 13).

RESULTS

After aortic unclamping, group LDTC-L showed higher incidence of spontaneous defibrillation (78.6% vs 30.8%, P =.0213), higher plasma nitrate + nitrite in the coronary sinus effluent (32.5 +/- 4.1 vs 28.7 +/- 3.0 micromol/L, P =.0013), lower differences between coronary sinus effluent and arterial blood in the percentage ratio of nitrotyrosine to tyrosine (myocardium-derived peroxynitrite; 2.987% +/- 0.576% vs 3.951% +/- 0.952%, P =.0036), and plasma polymorphonuclear-elastase (113.9 +/- 21.3 vs 155.5 +/- 41.6 microg/L, P =.0029) and malondialdehyde (2.75 +/- 0.67 vs 4.02 +/- 0.96 micromol/L, P =.0005) than group CONT did. Postoperatively, group LDTC-L showed lower human-heart fatty acid-binding protein (111.4 +/- 25.2 vs 156.4 +/- 38.6 IU/L, P =.0013), lower creatine kinase-muscle and brain (19.2 +/- 4.7 vs 24.8 +/- 6.5 IU/L, P =.0120), and smaller requirement of catecholamine (5.44 +/- 2.29 vs 8.45 +/- 3.42 microg x kg(-1) x min(-1), P =.0122). There were no significant differences in these parameters between groups LDTC-S and CONT-S.

CONCLUSIONS

This study demonstrated that leukocyte-depleted terminal blood cardioplegia provided superior myocardial protective effects and regulated myocardial-derived nitric oxide and peroxynitrite production only for patients undergoing aortic crossclamping for more than 120 minutes. The results suggest that prolonged aortic crossclamping deteriorates the tolerance to leukocyte-mediated myocardial injury accompanied by endothelial dysfunction associated with nitric oxide and peroxynitrite production.

Microvascular Inflammatory Response in Cardiac Surgery

Cardiac surgical procedures, with or without cardiopulmonary bypass, elicit a systemic inflammatory response in patients that induces the elaboration of multiple cytokines, chemokines, adhesion molecules, and destructive enzymes. This inflammatory reaction involves multiple interdependent and redundant cell types and humoral cascades, which allows for amplification and positive feedback at numerous steps. This systemic inflammatory response ultimately results in a broad spectrum of clinical manifestations, with multiple organ failure being the most severe form. Investigative efforts have focused on understanding the mechanism of this systemic inflammatory response syndrome in order to develop potential therapeutic targets to inhibit it, thereby possibly decreasing postoperative morbidity and mortality. Multiple therapeutic methods have been investigated, including pharmacologic inhibitors and modifications of surgical technique and the cardiopulmonary bypass circuit. Although studies have demonstrated that the use of these therapies in experimental and clinical settings has attenuated the systemic inflammatory response, they have failed to conclusively show clinical benefit from these therapies. These therapies may be too specific to minimize the deleterious effects of a systemic inflammatory response that results from the activation of multiple, interdependent, and redundant inflammatory cascades and cell types. Hence, further studies that investigate the molecular and cellular events underlying the systemic inflammatory response syndrome and the resultant effects of anti-inflammatory therapies are warranted to ultimately achieve improvements in clinical outcome after cardiac surgical procedures.

Cardioplegia in pediatric cardiac surgery: do we believe in magic?

Cardioplegia has become the gold standard of myocardial protection for practically every type of heart surgery during which the ascending aorta must be clamped. Although there is little doubt about the efficacy of cardioplegia in the adult heart, there are few studies on the pediatric heart and their results are contradictory. The physiology of pediatric heart muscle differs considerably from that of the adult myocardium. The pediatric heart distinguishes itself from that of the adult most impressively in its greater tolerance for ischemia. This ischemia tolerance is enhanced by the use of hypothermia. Considering that hypothermia is a powerful tool to prolong ischemia tolerance and that most pediatric cardiac surgeons report similar results using different types of cardioplegia, some surgeons are tempted to suspect that the contribution of the cardioplegia composition to protecting the pediatric heart may be overestimated. This provocative statement is critically discussed in this article. We examine the protective potential of cardioplegia (in various compositions), or of hypothermia, or of both in pediatric cardiac surgery. We pay special attention to several key differences between the physiologies of the pediatric myocardium and the adult myocardium and attempt to relate them to the available surgical methods of myocardial protection. We conclude that the composition of cardioplegia indeed is an important component of successful operative management in pediatric heart surgery. We provide evidence that the benefit of cardioplegia over hypothermia alone is minor at low temperatures (below 15 degrees C), but becomes substantial when the temperature increases.

Blood cardioplegia filtration

The introduction of blood cardioplegia has been proven to limit ischaemia and reperfusion injury in cardiac surgery. But the presence of activated neutrophils in the capillary bed may cause further damage. Leukocyte filters have been shown to be very effective in reducing the leukocytes in blood cardioplegia to less than 10%. Leukocyte depletion of blood cardioplegia provides an excellent approach to minimizing myocardial injury, predominantly in high-risk cardiac surgery.

Oxidative stress and neutrophil activation—the two keystones of ischemia/reperfusion injury

The widespread introduction of fibrinolytics and recently also PTCA in the treatment of myocardial infarction has changed the picture of modern cardiology. But this therapy also raises new problems and challenges. One of them is the occurrence of extensive tissue injury caused by reperfusion. Reinstitution of oxygen to the ischemic tissues initiates various processes leading to generation of reactive oxygen species (ROSs). Acting on the plasma membrane ROS damage its organization and release various proinflammatory agents. Different proteins, including receptors, ionic channels, transporters or components of transduction pathways are substrates of oxidation by ROSs. Their changed structure results in altered functioning and disruption of vital cellular processes. Another key factor of reperfusion injury is activation and infiltration of infarcted area by polymorphonuclear leukocytes (PMNs). Multiple studies identified consecutive stages of PMN activation and substances being involved in it. Main interest lies in cellular adhesion molecules, particularly selectins and beta2 integrins, as their antagonists were repeatedly found to diminish neutrophil activation and infarct size. Nevertheless new publications strike at the foundations of the established order and confront the relation between neutrophil infiltration and infarct size. PMNs are linked by close ties to other cells involved in inflammatory response. Seemingly also in cardiac ischemia-reperfusion injury, the activity of neutrophils is modulated by lymphocytes and macrophages. The article describes mutual interactions between different factors involved in the reperfusion injury that may enable preparing new treatments, hopefully as effective and successful as reperfusion therapy.

The role of leukodepletion in limiting ischemia/reperfusion damage in the heart, lung and lower extremity

This article describes the experimental infrastructure and subsequent clinical application of a comprehensive reperfusion strategy to limit the injury following ischemia, resulting in an improvement in post operative organ function. In particular, it examines the role of luekodepletion in minimizing damage and improving functional outcome in the heart, lung and lower extremity. During cardiothoracic procedures, various organs can be subjected to temporary ischemia, particularly the heart (cardioplegic arrest), lung (transplant), and lower extremity (femoral canulation, IABP). The background of ischemia/reperfusion injury is discussed as it applies to each of these 3 organs, as well as findings that ischemia followed by reperfusion results in a similar injury in each organ. Data are then presented to demonstrate that a comprehensive reperfusion strategy, utilizing a modified substrate-enriched blood reperfusate delivered at a low pressure can limit this injury, and that adding white blood cell filtration significantly improves the efficacy of this approach. These principles have now been used in a series of patients undergoing various surgical procedures with excellent results. Application of these concepts may significantly improve the outcome in patients undergoing procedures which subject these organs to temporary ischemia.

A review of leukofiltration in cardiac surgery: the time course of reperfusion injury may facilitate study design of anti-inflammatory effects

The systemic inflammatory response syndrome (SIRS) is a well-recognized phenomenon attending cardiopulmonary bypass (CPB) surgery. SIRS leads to costly complications and several strategies intended to ameliorate the symptoms have been studied, including leukocyte reduction using filtration. Although the body of work suggests that leukoreduction attenuates SIRS, discrepancies remain within the literature. The recent literature is reviewed, highlighting the areas where concordance is lacking. Investigations into many promising device-related technologies are often deterred by the high costs of clinical trials. Adding to costs is the fact that clinical end points generally require large sample sizes. An understanding, however, of the pathogenesis of reperfusion injury can guide the investigator to choose physiologic response measures that correlate well with clinical outcome, but feature low inherent variability, allowing for clinical trials with smaller sample sizes. With this goal in mind, a model for the pathogenesis of reperfusion injury is described. Using a model of reperfusion injury as underpinnings for the design of prospective pilot studies, we show that salvaged blood reinfused following CPB elicits time-dependent effects on pulmonary function as predicted by the model. Data are illustrative of principles that could expand the scope of clinical investigations designed to validate the use of physiologic response measures as correlates of clinical outcome. Such investigations would target surrogate markers of clinical outcome, measured at clinically relevant times. Once validated, these surrogate markers would, thereafter, become economical screening tools for clinical studies of device-related or pharmacological anti- inflammatory interventions.

A review of leukofiltration therapy for decreasing the morbidity associated with cardiopulmonary bypass and acute inflammatory bowel disease

Complications of cardiopulmonary bypass (CPB) and acute inflammatory bowel disease (IBD) are associated with increased morbidity and cost. During reperfusion post-CPB, activated neutrophils adhere to microvascular endothelial cells mediated by cell adhesion molecules (CAMs) and cytokines/chemokines with subsequent myocardial damage caused by activated neutrophil-derived oxidants and enzymes. Leukofiltration was shown to reduce myocardial reperfusion injury and improve gas exchange as suggested by improvements in surrogate markers of inflammation and clinical end points. In acute IBD, characterized by rectal bleeding and protracted hospital stays, circulating neutrophils emigrate to the inflamed colon and adhere to microvascular endothelial cells by CAMs. Multiple treatments with leukofiltration in IBD were shown to induce long-term remission of acute IBD. Hence, leukofiltration may reduce reperfusion injury and rectal bleeding in CPB and IBD, respectively, and therefore decrease the morbidity and cost associated with these diseases.

First-stage palliation for hypoplastic left heart syndrome in the twenty-first century

Improved understanding of the postoperative physiology and experience with the surgical techniques and perioperative care of patients with hypoplastic left heart syndrome have resulted in improved outcomes. Over the past few years, numerous modifications to the intraoperative and postoperative management of these patients have been described. It is likely that in combination, these modifications and better understanding of the unique physiology after the Norwood procedure are responsible for decreasing early mortality. This review describes and discusses the current surgical and medical management of patients undergoing first-stage palliation for hypoplastic left heart syndrome and its variants.

Leukocyte filtration in cardiac surgery: a review

Leukocyte filtration has evolved as an important technique in cardiac surgery with cardiopulmonary bypass to prevent pathogenic effector functions mediated by activated leukocytes. The underlying mechanisms that result in an improvement of laboratory variables as well as clinical outcome are not resolved yet. Moreover, the optimum strategy for the use of current filtration technology has not been systematically evaluated. This paper, therefore, reviews how activated leukocytes may lead to tissue damage, summarizes the known effects of leukocyte filtration on clinical outcome and laboratory parameters, and deals with current experimental and clinical efforts to further limit the pathogenic effects of leukocytes in cardiac surgery.

Controlled nicorandil administration for myocardial protection during coronary artery bypass grafting under cardiopulmonary bypass

Nicorandil is a hybrid potassium channel opener, and recent experimental studies have demonstrated its efficacy in myocardial protection against ischemia-reperfusion. This clinical study was designed to examine the myocardial protective effect of nicorandil administered during cardiopulmonary bypass. Seventy adult patients, 53 men and 17 women, undergoing elective coronary artery bypass grafting were randomly assigned to two groups, one receiving nicorandil during cardiopulmonary bypass (group N, n = 35) and the other receiving no nicorandil for control (group C, n = 35). Nicorandil was administered at each dose of 0.1 mg/kg into the cardiopulmonary bypass circuit according to the following schedule: (1) bolus injection at the initiation of cardiopulmonary bypass, (2) continuous infusion for 5 min before aortic cross-clamping, (3) bolus administration at 5 min before reperfusion, and (4) continuous infusion for 5 min before reperfusion. The time required for achieving cardiac arrest after the initial cardioplegia was significantly reduced in group N in comparison with that in group C. After aortic unclamping, the number of patients showing a significant ST segment change on the electrocardiogram was significantly fewer in group N, whereas the number of patients showing spontaneous recovery of heart beat was significantly greater. As for the myocardial protective effect, group N showed lower plasma levels of malondialdehyde, human-heart fatty acid-binding protein, and peak creatine kinase-MB, and required lower doses of catecholamine. Our results suggest that nicorandil administration during cardiopulmonary bypass provides enhanced myocardial protective effects against ischemia-reperfusion in patients undergoing coronary artery bypass grafting.

Myocardial protection with leukocyte depletion in cardiac surgery

A role of neutrophils in ischemia-reperfusion injury has been focused on as one of the mediating factors of inflammatory reactions. Current studies have reported the efficacy of leukocyte-depletion in reperfusion by using leukocyte removal filter to attenuate reperfusion injury during open heart surgeries. For clinical application, we have introduced leukocyte-depleted terminal blood cardioplegia (LDTC) in adult patients and leukocyte-depleted blood cardioplegia in pediatric patients. The results of elective surgery in noncompromised LDTC did not significantly alter the results in terms of leakage of creatine kinase (CK)-MB, production of malondialdehyde from myocardium, and dopamine dose required at the weaning from cardiopulmonary bypass compared with the whole-blood reperfusion or with terminal cardioplegia alone. In contrast, the results in emergency coronary artery bypass graft (CABG) patients differed significantly between the LDTC group and the other two groups. Leukocyte-depleted reperfusion was also effective in a similar fashion for patients with severe left ventricular hypertrophy caused by chronic aortic valve disease. Leukocyte-depleted blood cardioplegia was useful in pediatric patients. Thus, leukocyte depletion may be beneficial as an adjunct to terminal blood cardioplegia or blood cardioplegia during cardiac surgery to attenuate leukocyte-mediated ischemia-reperfusion injury in patients with compromised hearts, such as those with preoperative ischemic insults, severe left ventricular hypertrophy, and in pediatric patients.

In vivo models of myocardial ischemia and reperfusion injury: application to drug discovery and evaluation

This review discusses the pharmacology of regional myocardial ischemia and reperfusion (I/R) injury and the utilization of in vivo animal models in the preclinical development of novel therapeutic compounds. The manuscript aims to provide an overview of a number of different cardioprotective strategies that have been successful from a preclinical perspective and to also present where possible results of clinical trials of the respective compounds. Myocardial ischemia reperfusion injury may be manifested as myocardial stunning, ventricular arrhythmias, coronary vascular dysfunction, or the development of a myocardial infarct. This review is principally concerned with preclinical studies related to reduction of infarct size. The pathophysiology of the reperfusion injury process is complex, including primarily cellular and humoral components of inflammation, as well as myocellular ionic and metabolic disturbances. This review will discuss strategies directed at oxygen-derived free radicals, neutrophils, adenosine, and the sodium-hydrogen exchanger (NHE). The results of preclinical cardioprotective studies are influenced by the paradigm used therefore methodological considerations will also be presented where appropriate.