Reperfusion injury associated with one-fourth of deaths after coronary artery bypass grafting

ALDH2 polymorphism and myocardial infarction: From alcohol metabolism to redox regulation

Acute myocardial infarction (AMI) remains a leading cause of death worldwide. Increased formation of reactive oxygen species (ROS) during the early reperfusion phase is thought to trigger lipid peroxidation and disrupt redox homeostasis, leading to myocardial injury. Whilst the mitochondrial enzyme aldehyde dehydrogenase 2 (ALDH2) is chiefly recognised for its central role in ethanol metabolism, substantial experimental evidence suggests an additional cardioprotective role for ALDH2 independent of alcohol intake, which mitigates myocardial injury by detoxifying breakdown products of lipid peroxidation including the reactive aldehydes, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE). Epidemiological evidence suggests that an ALDH2 mutant variant with reduced activity that is highly prevalent in the East Asian population increases AMI risk. Additional studies have uncovered a strong association between coronary heart disease and this ALDH2 mutant variant. It appears this enzyme polymorphism (in particular, in ALDH2*2/2 carriers) has the potential to have wide-ranging effects on thiol reactivity, redox tone and therefore numerous redox-related signaling processes, resilience of the heart to cope with lifestyle-related and environmental stressors, and the ability of the whole body to achieve redox balance. In this review, we summarize the journey of ALDH2 from a mitochondrial reductase linked to alcohol metabolism, via pre-clinical studies aimed at stimulating ALDH2 activity to reduce myocardial injury to clinical evidence for its protective role in the heart.

Continuous Myocardial Perfusion during Distal Anastomosis of Acute Type A Aortic Dissection

BACKGROUND

 The effect of continuous myocardial perfusion (CMP) on the surgical results of acute type A aortic dissection (ATAAD) remains unclear.

METHODS

 From January 2017 to March 2022, 141 patients who underwent ATAAD (90.8%) or intramural hematoma (9.2%) surgery were reviewed. Fifty-one patients (36.2%) received proximal-first aortic reconstruction and CMP during distal anastomosis. Ninety patients (63.8%) underwent distal-first aortic reconstruction and were placed in traditional cold blood cardioplegic arrest (CA; 4°C, 4:1 blood-to-Plegisol) throughout the procedure. The preoperative presentations and intraoperative details were balanced using inverse probability of treatment weighting (IPTW). Their postoperative morbidity and mortality were analyzed.

RESULTS

 The median age was 60 years. The incidence of arch reconstruction in the unweighted data was higher in the CMP compared with the CA group (74.5 vs 52.2%, p = 0.017) but was balanced after IPTW (62.4 vs 58.9%, p = 0.932, standardized mean difference = 0.073). The median cardiac ischemic time was lower in the CMP group (60.0 vs 130.9 minutes, p < 0.001), but cerebral perfusion time and cardiopulmonary bypass time were similar. The CMP group did not demonstrate any benefit in the reduction of the postoperative maximum creatine kinase-MB ratio (4.4 vs 5.1% in CA, p = 0.437) or postoperative low cardiac output (36.6 vs 24.8%, p = 0.237). Surgical mortality was comparable between groups (15.5% in CMP vs 7.5% in the CA group, p = 0.265).

CONCLUSION

 Application of CMP during distal anastomosis in ATAAD surgery, irrespective of the extent of aortic reconstruction, reduced myocardial ischemic time but did not improve cardiac outcome or mortality.

Effects of Melatonin on Cardiac Injury and Inflammatory Biomarkers in Patients Undergoing Coronary Artery Bypass Graft Surgery: a Meta-analysis

INTRODUCTION

The antiinflammatory and antioxidative effects of melatonin have been established in recent years. Several studies indicate that oxidative stress and inflammation are key drivers of post-coronary artery bypass graft (CABG) surgery complications. In the present study, we aimed to investigate the effects of melatonin on cardiac injury and inflammatory biomarkers in CABG candidates.

METHODS

Embase, Medline/PubMed, Web of Science, Scopus, and the Cochrane library were searched up to 5 June 2022. All randomized controlled trials examining cardiac injury and inflammatory biomarkers of CABG patients who received melatonin were included. The random-effects model was utilized to perform the analysis.

RESULTS

A total of 947 citations were retrieved through database searches. Finally, five articles (six trials with 342 patients) were included after the screening. Melatonin supplementation led to a significant reduction in cardiac troponin I (CTnI) [weighted mean difference(WMD): -2.28 ng/ml; 95% CI -2.87, -1.69; P < 0.01; I²: 91.25%] and high sensitivity-C reactive protein (hs-CRP) levels (WMD: -0.62 mg/L; 95% CI -0.73, -0.5; P < 0.01; I²: 99.98%) in patients undergoing CABG surgery. We found a nonsignificant decrease in creatine kinase isoenzyme muscle/brain (CK-MB) levels (WMD: -2.87 ng/ml; 95% CI -5.97, 0.23; P = 0.07; I²: 99.98%) after melatonin supplementation. No publication bias was found according to Egger's test.

CONCLUSION

Melatonin supplementation may be useful in reducing cardiac injury and inflammatory biomarkers in CABG candidates. Future studies should investigate the clinical significance of these findings.

A review of potential mechanisms and uses of SGLT2 inhibitors in ischemia-reperfusion phenomena

Recently added to the therapeutic arsenal against chronic heart failure as a first intention drug, the antidiabetic drug-class sodium-glucose cotransporter-2 inhibitors (SGLT2i) showed efficacy in decreasing overall mortality, hospitalization, and sudden death in patients of this very population, in whom chronic or acute ischemia count among the first cause. Remarkably, this benefit was observed independently from diabetic status, and benefited both preserved and altered ventricular ejection fraction. This feature, observed in several large randomized controlled trials, suggests additional effects from SGLT2i beyond isolated glycemia control. Indeed, both in-vitro and animal models suggest that inhibiting the Na⁺/H⁺ exchanger (NHE) may be key to preventing ischemia/ reperfusion injuries, and by extension may hold a similar role in ischemic damage control and ischemic preconditioning. Yet, several other mechanisms may be explored which may help better target those who may benefit most from SGLT2i molecules. Because of a large therapeutic margin with few adverse events, ease of prescription and potential pharmacological efficacity, SGLT2i could be candidate for wider indications. In this review, we aim to summarize all evidence which link SGLT2i and ischemia/reperfusion injuries modulation, by first listing known mechanisms, including metabolic switch, prevention of lethal arrythmias and others, which portend the latter, and second, hypothesize how the former may interact with these mechanisms.

Clinical management of postcardiotomy shock in adults

Postcardiotomy cardiogenic shock represents the most serious expression of low cardiac output syndrome after cardiac surgery. Although infrequent, it is a relevant condition due to its specific and complex pathophysiology and important morbidity-mortality. The diagnosis requires a high index of suspicion and multimodal hemodynamic monitoring, where echocardiography and the pulmonary arterial catheter play a main role. Early and multidisciplinary management should focus on the management of postoperative or mechanical complications and the optimization of determinants of cardiac output through fluid therapy or diuretic treatments, inotropic drugs and vasopressors/vasodilators and, in the absence of a response, early mechanical circulatory support. The aim of this paper is to review and update the pathophysiology, diagnosis and management of postcardiotomy cardiogenic shock.

Cellular mechanisms and pathways in myocardial reperfusion injury

Despite the progress of cardiovascular medicine, ischemia-reperfusion injury can contribute to increased mortality and prolonged hospitalization after myocardial infarction. Ischemia-reperfusion injury pathophysiology encompasses many cells including cardiomyocytes, fibroblasts, mesenchymal stromal cells, vascular endothelial and smooth muscle cells, platelets, polymorphonuclear cells, macrophages, and T lymphocytes. However, specific mechanisms for all contributing cells and molecular pathways are still under investigation. What is definitely known is that endothelial dysfunction, immunity activation and inflammatory response are crucial events during ischemia-reperfusion injury while toll-like receptors, inflammasomes, reactive oxygen species, intracellular calcium overload and mitochondrial permeability transition pore opening consist of key molecular mediators. Indicatively, cardiac fibroblasts through inflammasome activation mediate the initial inflammatory response. Cardiac mesenchymal stromal cells can respond to myocardial injury by pro-inflammatory activation. Endothelial cell activation contributes to the impaired vasomotion, inflammation and thrombotic events and together with platelet activation leads to microcirculation dysfunction and polymorphonuclear cells recruitment promoting inflammation. Polymorphonuclear cells and monocytes/macrophages subsets are critically involved in the inflammation process by producing toxic proteolytic enzymes and reactive oxygen species. T cells subsets are also involved in several stages of ischemia-reperfusion injury. In this review, we summarize the specific contribution of each of the above cells and the related molecular pathways in the pathophysiology of ischemia-reperfusion injury.

Comparison of heat monitoring-based myocardial protection strategy with classic myocardial protection method in isolated coronary artery bypass surgery patients

OBJECTIVE

In this study, we aimed to compare patients who have a myocardial protection strategy based on myocardial temperature monitorization with those who had myocardial protection with conventional intermittent cardioplegia.

METHODS

Twenty-six patients undergoing coronary artery bypass graft surgery were included into the study. Patients were prospectively grouped into two; myocardial protection based on temperature monitoring (group 1, n = 11) and those who had cardioplegia every 20 min (group 2, n = 15) during aortic cross-clamping. In all patients, cold blood cardioplegia was used. Coronary sinus blood sampling was performed immediately before aortic cross-clamping, after 2, 20, and 40 min of aortic clamping and tumor necrosis factor-alpha, malondialdehyde, creatinine kinase-myocardial band isoenzyme (MB), troponin I, lactate, and pH were studied. In addition, myocardial biopsy was taken before and immediately after cross-clamping to evaluate cardiomyocyte apoptosis with caspase-3 tunnel immunostaining.

RESULTS

There were no differences in clinical parameters like early mortality, extubation time, inotropic requirements, postoperative drainage, intensive care unit, and hospitalization time between two groups. In addition, blood and blood products were similar in two groups. In group 2, after cross-clamping, troponin I and creatinine kinase-MB values were significantly higher than the other group. In myocardial biopsies, the caspase immunostaining score, before removal of aortic cross-clamp was significantly higher in group 2 than the samples taken before aortic clamping.

CONCLUSION

Our results show that there is no difference between temperature-based myocardial protection strategy with conventional intermittent cardioplegia delivery. We think that the number of patients in our study is less and that the patient population is not a homogeneous structure is the most important limiting factor of our study. Increasing the number of patients, with particularly those who have myocardial dysfunction would help augment the possible different effects of two cardioplegic techniques on myocardial protection.

Comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting or correction of valvular heart disease

Introduction: Our aim was to perform a comparative study of short-term cardiovascular autonomic control in cardiac surgery patients who underwent coronary artery bypass grafting (CABG) or surgical correction of valvular heart disease (SCVHD ). Methods: The synchronous 15 minutes records of heart rate variability (HRV) and finger's photoplethysmographic waveform variability (PPGV) were performed in 42 cardiac surgery patients (12 women) aged 61.8 ± 8.6 years (mean ± standard deviation), who underwent CABG, and 36 patients (16 women) aged 54.2 ± 14.9 years, who underwent SCVHD , before surgery and in 5-7 days after surgery. Conventional time and frequency domain measures of HRV and index S of synchronization between the slow oscillations in PPGV and HRV were analyzed. We also calculated personal dynamics of these indices after surgery. Results: We found no differences (Р > 0.05) in all studied autonomic indices (preoperative and post-surgery) between studied patients' groups, except for the preoperative heart rate, which was higher in patients who underwent SCVHD (P = 0.013). We have shown a pronounced preoperative and post-surgery variability (magnitude of inter-quartile ranges) of all autonomic indices in studied patients. In the cluster analysis based on cardiovascular autonomic indices (preoperative and post-surgery), we divided all patients into two clusters (38 and 40 subjects) which did not differ in all clinical characteristics (except for the preoperative hematocrit, P = 0.038), index S, and all post-surgery HRV indices. First cluster (38 patients) had higher preoperative values of the HR, TP, HF, and HF%, and lower preoperative values of the LF% and LF/HF. Conclusion: The variability of cardiovascular autonomic indices in on-pump cardiac surgery patients (two characteristic clusters were identified based on preoperative indices) was not associated with their clinical characteristics and features of surgical procedure (including cardioplegia).

Does beating heart surgery technique reduce the mortality and morbidity after redo valve operations?

Aim: The aim of this study was to determine the effect of beating heart technique on mortality and morbidity after redo valve operations. Material and Method: Fifty-two patients who had redo open-heart surgery between May 2005 and November 2006 in a Hospital included in this prospective study. All patients had a history of open-heart surgery with median sternotomy. Thirty-two patients who had redo open-heart surgery with beating heart technique were included in Group 1 and 20 patients who had redo open-heart surgery with conventional cardioplegic myocardial arrest technique were included in Group 2. Patients who had any cardiac surgery without median sternotomy were excluded. Results: Functional capacity according to New York Heart Association classification was significantly lower and number of patients with chronic obstructive lung disease was significantly higher in Group 1 (p = 0.011 and p = 0.003 respectively). There was no significant difference in other preoperative variables. Operation, cardiopulmonary bypass and aortic cross-clamping times were significantly higher in Group 2 (p = 0.001, p = 0.003, p = 0.04 respectively). Mechanical ventilation, inotropic agent support and hospitalization times were significantly higher in Group 2 (p < 0.05). Intensive care unit time was significantly longer in Group 1 (p < 0.05). Drainage volumes, blood product transfusion volumes, intra-aortic balloon pump support times were not significantly different between the groups. Conclusion: Beating heart technique in redo heart valve operations has better outcomes than the conventional technique.

The spectrum of myocardial homeostasis mechanisms in the settings of cardiac surgery procedures (Review)

Classic cardiac surgery, determined through the function of cardiopulmonary bypass machine and myocardial cardioplegic arrest, represents the most controlled scenario for cardiomyocyte homeostatic disturbances due to systemic inflammatory response and myocardial reperfusion injury. An increasing number of studies have demonstrated that myocardial cell homeostasis in cardiac surgery procedures is a sequence of molecularly interrelated and overlapping mechanisms in the form of apoptosis, autophagy and necrosis, which are activated by a plethora of induced inflammatory mediators and gene-related signaling pathways. In this study, we outline the molecular mechanisms of the cardiomyocyte adaptive homeostatic process and the associated clinical implications, in the settings of classic cardiac surgery procedures.

Effects of remote ischemic preconditioning in high-risk patients undergoing cardiac surgery (Remote IMPACT): a randomized controlled trial

BACKGROUND

Remote ischemic preconditioning is a simple therapy that may reduce cardiac and kidney injury. We undertook a randomized controlled trial to evaluate the effect of this therapy on markers of heart and kidney injury after cardiac surgery.

METHODS

Patients at high risk of death within 30 days after cardiac surgery were randomly assigned to undergo remote ischemic preconditioning or a sham procedure after induction of anesthesia. The preconditioning therapy was three 5-minute cycles of thigh ischemia, with 5 minutes of reperfusion between cycles. The sham procedure was identical except that ischemia was not induced. The primary outcome was peak creatine kinase-myocardial band (CK-MB) within 24 hours after surgery (expressed as multiples of the upper limit of normal, with log transformation). The secondary outcome was change in creatinine level within 4 days after surgery (expressed as log-transformed micromoles per litre). Patient-important outcomes were assessed up to 6 months after randomization.

RESULTS

We randomly assigned 128 patients to remote ischemic preconditioning and 130 to the sham therapy. There were no significant differences in postoperative CK-MB (absolute mean difference 0.15, 95% confidence interval [CI] -0.07 to 0.36) or creatinine (absolute mean difference 0.06, 95% CI -0.10 to 0.23). Other outcomes did not differ significantly for remote ischemic preconditioning relative to the sham therapy: for myocardial infarction, relative risk (RR) 1.35 (95% CI 0.85 to 2.17); for acute kidney injury, RR 1.10 (95% CI 0.68 to 1.78); for stroke, RR 1.02 (95% CI 0.34 to 3.07); and for death, RR 1.47 (95% CI 0.65 to 3.31).

INTERPRETATION

Remote ischemic precnditioning did not reduce myocardial or kidney injury during cardiac surgery. This type of therapy is unlikely to substantially improve patient-important outcomes in cardiac surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01071265.

Remote ischemic preconditioning is a safe adjuvant technique to myocardial protection but adds no clinical benefit after on-pump coronary artery bypass grafting

BACKGROUND

To evaluate the impact of remote ischemic preconditioning (RIPC) on clinical outcome, biological markers of myocardial injury, and its safety in patients undergoing on-pump coronary artery bypass grafting (CABG).

MATERIAL AND METHODS

This study was conducted at Ch. Pervaiz Elahi Institute of Cardiology (CPEIC) in Multan. The study took place from March 2012 to June 2013. Patients were randomly placed into two groups. Group A (N = 32) did not undergo RIPC; Group B (N = 35) received RIPC after induction of anesthesia. Similar standard general anesthesia, cardiopulmonary technique, myocardial protection strategies, and surgical techniques were used in both groups except the protocol for RIPC. Following postoperative outcome, i.e. cardiac defibrillation after removal of aortic cross clamp during the period of rewarming, demand for intra-aortic balloon pump (IABP), demand for antiarrhythmic before leaving the operation room, postoperative creatine kinase-myocardial band (CK-MB) level (at 1h, 12h, 24h, and 48h after surgery), postoperative serum creatinine level on first postoperative day, postoperative ejection fraction (EF) on third postoperative day, in-hospital mortality, and one-year mortality were noted, prospectively. Safety of protocol of RIPC was estimated by limb ischemia monitored by pulse oximetry during and after procedure of RIPC and postoperative neurapraxia by nerve examination of right upper limb.

RESULTS

Post aortic cross clamp release cardiac defibrillation, demand for IABP, demand for high inotropes, and use of antiarrhythmic in the operation room were statistically insignificant in the non-RIPC and RIPC group with P values of .54, .78, .16, and .16, respectively. Mean postoperative CK-MB level (IU/L) showed the following results: At 1h (Group A 20.94 + 1.66, Group B 20.57 + 1.54, P = .35), at 12h (Group A 27.13 + 1.85, Group B 28.05 + 3.04, P = .135), at 24h (Group A 27.63 + 1.7, Group B 27.85 + 2.2, P = .63), and at 48h (Group A 22.95 + 2.76, Group B 23.27 + 3.6, P = .69). First postoperative day serum creatinine (Group A 1.29 + 0.395, Group B 1.33 + 0.57, P = .77) and postoperative ejection fraction percentage on the third postoperative day (Group A 50.78 + 8.72, Group B 50.57 + 8.38, P = .92) showed no statistical difference between two groups. Postoperative low cardiac output state, in-hospital mortality, and one-year mortality also were statistically insignificant between the groups with P values of .93, .29, and .33, respectively. None of the patients in either group showed evidence of limb ischemia and neurapraxia of the right upper limb.

CONCLUSION

RIPC is a safe technique, but it does not have additional clinical benefit after on-pump CABG surgery in the presence of a standard myocardial protective strategy.

Keeping the heart empty and beating: an alternative technique to preserve hypertrophied hearts during valvular surgery

INTRODUCTION

To determine whether keeping the heart empty and beating is an effective technique to preserve hypertrophied pig hearts, and to investigate the underlying mechanism.

METHODS

Ten Bama Miniature pigs with hypertrophied hearts were divided into 2 groups (n = 5 in each group). One group underwent normothermic normokalemic simultaneous perfusion (NNSP). The other group was subjected to normothermic hypermokalemic simultaneous perfusion (NHSP) and used as controls. Cardiac contractive function, myocardial energy metabolism and myocardial perfusion were assessed using magnetic resonance imaging. Western blot analysis was carried out to determine the expression of Troponin I (cTnI), Troponin T (cTnT), SM-MHC, Casapase-3 and PARP4. TUNEL assay was used to detect apoptotic cardiomyocytes.

RESULTS

Keeping the heart empty and beating with NNSP improved the preservation of contractile function in comparison with cardioplegic arrest using NHSP. No significant differences existed in the effects of NNSP and NHSP in maintaining myocardial energy metabolism. 13 % perfusion defects areas were found in one heart in the NHSP group, whereas none was found in all other hearts in both groups. The expressions of cTnI, cTnT, Casapase-3 and PARP4 in NHSP group were abundantly increased compared to NNSP group as measured by Western blotting. Conversely, the expression of SM-MHC in NHSP group was reduced compared with NNSP group. The number of TUNEL positive nuclei per mm(2) area was significantly increased in NHSP group compared with NNSP group.

CONCLUSIONS

Keeping the heart beating with NNSP is an alternative technique to preserve hypertrophied hearts during valvular surgery.

The Effectiveness of Preoperative Trimetazidine on Myocardial Preservation in Coronary Artery Bypass Graft Patients: A Systematic Review and Meta-Analysis

Background: Coronary artery bypass grafting (CABG) is a key and effective surgical treatment modality for coronary artery disease. Unfortunately, ischemia-reperfusion injury during and after CABG can lead to reversible and irreversible myocardial damage. Trimetazidine [1-(2,3,4-trimethoxybenzyl)piperazine dihydrochloride] is a metabolic anti-ischemic agent with demonstrated cardioprotective effects; however, its effects with respect to myocardial preservation in CABG patients remain unclear. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to investigate the effectiveness of myocardial preservation of preoperative trimetazidine therapy in CABG patients by assessing the postoperative levels of several blood-based biochemical markers of myocardial injury, including creatine kinase (CK), creatine kinase-muscle and brain (CK-MB), creatine phosphokinase (CPK), troponin T (TnT) and troponin I (TnI). The RCTs were classified into two subgroup analyses by the timing of sample collection (either ≤12 or >12 h after CABG). Results: Six RCTs were finally included in the meta-analysis. The pooled effect sizes showed significantly lower postoperative levels of CK, CK-MB, TnT and TnI in the trimetazidine-treated CABG patients relative to control CABG patients. However, there were no significant differences in the postoperative CPK levels between trimetazidine-treated CABG patients relative to control CABG patients. In both the ≤12 and >12 h post-CABG subgroup analyses, significant differences in CK, CK-MB, TnT and TnI were detected between the trimetazidine-treated CABG patients relative to control CABG patients. Conclusions: Preoperative trimetazidine therapy appears to have a positive effect on myocardial preservation in CABG patients.

Adjuvant cardioprotection in cardiac surgery: update

Cardiac surgery patients are now more risky in terms of age, comorbidities, and the need for complex procedures. It brings about reperfusion injury, which leads to dysfunction and/or loss of part of the myocardium. These groups of patients have a higher incidence of postoperative complications and mortality. One way of augmenting intraoperative myocardial protection is the phenomenon of myocardial conditioning, elicited with brief nonlethal episodes of ischaemia-reperfusion. In addition, drugs are being tested that mimic ischaemic conditioning. Such cardioprotective techniques are mainly focused on reperfusion injury, a complex response of the organism to the restoration of coronary blood flow in ischaemic tissue, which can lead to cell death. Extensive research over the last three decades has revealed the basic mechanisms of reperfusion injury and myocardial conditioning, suggesting its therapeutic potential. But despite the enormous efforts that have been expended in preclinical studies, almost all cardioprotective therapies have failed in the third phase of clinical trials. One reason is that evolutionary young cellular mechanisms of protection against oxygen handling are not very robust. Ischaemic conditioning, which is among these, is also limited by this. At present, the prevailing belief is that such options of treatment exist, but their full employment will not occur until subquestions and methodological issues with the transfer into clinical practice have been resolved.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

Beating heart as an alternative for closure of secundum atrial septal defect

We repaired secundum atrial septal defect in 135 consecutive patients from February 2003 to December 2010. There were 98 females and 37 males, with a mean age of 22.92 ± 17.46 years (range, 3-55 years). To prevent myocardial dysfunction and systemic embolism caused by the conventional technique, the operation was performed with a beating heart under cardiopulmonary bypass in 63 cases, and compared the data retrospectively with cases treated under aortic crossclamping, to determine the safety of the beating-heart technique and to evaluate risk factors for embolism in stroke patients. Patient age and size of defect were similar in both groups. There was no death and no residual shunt in either group. The mean cardiopulmonary bypass time was 36.84 ± 9.8 min in the beating-heart group and 43.13 ± 16.7 min in the crossclamp group. The ejection fraction and the incidence of postoperative arrhythmia were similar in both groups. There were no differences in blood products transfused, intensive care unit stay, hospital stay, or perioperative morbidity. In our experience, the results of the beating-heart technique were not different from the conventional technique.

Endogenous cardioprotection by ischaemic postconditioning and remote conditioning

Persistent myocardial ischaemia causes cell death if not rescued by early reperfusion. Millions of years in nature's laboratory have evolved protective responses that 'condition' the heart (and other tissues) to adapt to stressors, and these responses are applicable to the relatively new societal stress of myocardial ischaemia and reperfusion injury. Conditioning can be applied before (preconditioning), during (perconditioning), or after (postconditioning) the ischaemic stressor by imposing short periods of non-lethal ischaemia separated by brief periods of reperfusion. This conditioning protects multiple cell types and induces or rebalances a number of physiological and molecular pathways that ultimately attenuate necrosis and apoptosis. The seemingly disparate pathways may converge directly or indirectly on the mitochondria as a final effector, but other pathways not affecting mitochondria broaden the mechanisms of cardioprotection. The potential downsides of imposing even brief ischaemia directly on the heart somewhat tempered the enthusiasm for applying conditioning stimuli to the heart, but this hurdle was surmounted by applying ischaemia to remote organs and tissues in pre-, per-, and postconditioning. Although the clinical translation of remote per- and postconditioning has been rapid compared with classical preconditioning, there are numerous basic questions that require further investigation, and wider adoption awaits large-scale randomized clinical trials. Pharmacological mimetics may provide another important therapeutic approach by which to treat evolving myocardial infarction.

Effect of citrate phosphate dextrose solution on reperfusion injury in coronary artery bypass surgical patients undergoing cardiopulmonary bypass

INTRODUCTION

Reperfusion injury is one of the most common phenomena associated with coronary artery bypass graft (CABG) .The mechanism of ischemia and reperfusion injury is not known precisely, but may be free radicals and other activated oxygen metabolites have an important role in tissue damage following reperfusion injury. This study was to evaluation of citrate solution effects on oxidative stress and cardiac function and Cardiac enzymes in patient's candidate to CABG.

METHODS

In Double blind clinical trial study in Tabriz University of medical science, 50 patients candidate to CABG randomly divided in two groups and matched together according to sex, age and NYHA class. In intervention group after surgery and before the opening of the aortic clamping solution warm blood containing citrate phosphate dextrose (CPD; 3cc/100cc), value (100cc/min/m2BSA) for three minutes was administered. In control group, only pure blood administered. Oxidative stress markers measured in five stages and cardiac enzymes measured in three stages of surgery.

RESULTS

Mean age 62.3±9.1 years including 30(60%) men and 20(40%) women. Ejection fractions between two groups were not significant before and after treatment. Administration of CPD was not significant effects on cardiac enzyme. Measurement of oxidative stress in different time were not different in malonil dialdehyde, superoxide dismutase and GPx but total antioxidant status were improved after intervention in compared with control group (p<0.001).

CONCLUSION

Results showed that CPD were positive effects of increasing in total antioxidant status after CABG, but in reduction of other oxidative markers were unlabeled.

Beating heart continuous coronary perfusion for valve surgery: what next for clinical trials?

Prior to the introduction of cardioplegia, beating heart continuous coronary perfusion (BHCCP) was the only available method of myocardial protection. Currently, cardiac surgery on cardiopulmonary bypass with cardioplegic arrest is the gold standard strategy. Cardioplegic arrest provides an easier and safer way to operate on a still heart. It enables the performance of a broader range of cardiac procedures, and avoids the potential difficulties of continuous perfusion on a beating heart. Despite the overall effectiveness and safety of cardioplegia, some adverse effects remain, mainly due to the insult of ischemia, which results in ischemic reperfusion injury. As a result BHCCP has seen a revival as an alternative to cardioplegia for performing complex valvular surgery. Increasing experience reporting safety and efficacy of BHCCP is being published. However, despite the reported advantages, current available evidence validating safety and efficacy of BHCCP is controversial. This article provides an overview of BHCCP highlighting the current best available evidence supporting this strategy, concerns, controversies and potential areas for further research.

Pathogenesis of myocardial ischemia-reperfusion injury and rationale for therapy

Since the initial description of the phenomenon by Jennings et al 50 years ago, our understanding of the underlying mechanisms of reperfusion injury has grown significantly. Its pathogenesis reflects the confluence of multiple pathways, including ion channels, reactive oxygen species, inflammation, and endothelial dysfunction. The purposes of this review are to examine the current state of understanding of ischemia-reperfusion injury, as well as to highlight recent interventions aimed at this heretofore elusive target. In conclusion, despite its complexity our ongoing efforts to mitigate this form of injury should not be deterred, because nearly 2 million patients annually undergo either spontaneous (in the form of acute myocardial infarction) or iatrogenic (in the context of cardioplegic arrest) ischemia-reperfusion.

Beating-Heart Valve Surgery: A Systematic Review

Beating-heart continuous coronary perfusion (BHCCP) has been promoted as an alternative to the technique of cardioplegic arrest in valve surgery. Its potential advantage is the elimination of cardioplegia and the corollary risk of ischemic reperfusion injury. The use of CCP has been recommended especially when performing more complex operations, such as mitral valve repair, and particularly as surgeons become more familiar with beating-heart coronary surgery. We conducted a systematic review to assess the strength of the evidence supporting the efficacy of BHCCP compared to cardioplegia in valve surgery. Thirty nine reports were identified. Of these, only two were randomized control trials. Overall the studies were generally of poor quality and had a low evidence level. In those studies, mortality and major morbidity from BHCCP were within acceptable levels, nevertheless, there was no advantage over cardioplegic arrest. On the other hand there is weak evidence that it may reduce functional and biochemical markers of myocardial injury. In conclusion, BHCCP is an operative strategy in valve surgery with some potential benefits. There is, however a need for a high quality, prospective, randomized control trial to establish the exact role for BHCCP in complex valve surgery.

Aortic Valve Replacement With On-Pump Beating Heart Technique

BACKGROUND

The aim of this study was to assess the efficacy and applicability of on-pump beating heart aortic valve replacement with retrograde coronary sinus (CS) warm blood perfusion.

METHODS

The prospective study included 14 consecutive patients who underwent aortic valve replacement with mechanical prosthesis using retrograde CS perfusion. The operative variables and early outcome of this procedure are presented.

RESULTS

Retrograde CS perfusion and venting the heart from the pulmonary vein provided good visualization of the operative field and performance of the operations without any difficulty. Partial oxygen pressures of CS perfusion blood and the returning blood from the coronary ostia were 288.5 +/- 34.4 and 39.6 +/- 4.6 mmHg, respectively. Postoperative peak creatine kinase-MB and troponin T values were mean 77.0 +/- 63.6 IU/L and mean 0.8 +/- 0.7 ng/mL, respectively. No mortality or major complication was observed and all the patients were discharged from the hospital in good condition.

CONCLUSIONS

On-pump beating heart aortic valve replacement with retrograde CS warm blood perfusion is a good surgical option, and has the advantage of maintaining physiologic condition of the heart throughout the procedure.

Postmortem angiography: review of former and current methods

OBJECTIVE

Postmortem investigations are becoming more and more sophisticated. CT and MRI are already being used in pathology and forensic medicine. In this context, the impact of postmortem angiography increases because of the rapid evaluation of organ-specific vascular patterns, vascular alteration under pathologic and physiologic conditions, and tissue changes induced by artificial and unnatural causes.

CONCLUSION

In this article, the advantages and disadvantages of former and current techniques and contrast agents are reviewed.

Inflammation, proinflammatory mediators and myocardial ischemia-reperfusion Injury

Ischemic myocardium must be reperfused to terminate the ischemic event; otherwise the entire myocardium involved in the area at risk will not survive. However, there is a cost to reperfusion that may offset the intended clinical benefits of minimizing infarct size, postischemic endothelial and microvascular damage, blood flow defects, and contractile dysfunction. There are many contributors to this reperfusion injury. Targeting only one factor in the complex web of reperfusion injury is not effective because the untargeted mechanisms induce injury. An integrated strategy of reducing reperfusion injury in the catheterization laboratory involves controlling both the conditions and the composition of the reperfusate. Mechanical interventions such as gradually restoring blood flow or applying postconditioning may be used independently in or conjunction with various cardioprotective pharmaceuticals in an integrated strategy of reperfusion therapeutics to reduce postischemic injury.

Cardiopulmonary bypass without ischemic arrest: a myocardial protection strategy for high-risk patients requiring urgent CABG

For patients requiring emergency coronary artery revascularization, mortality remains high. One of the primary reasons is poor functional and metabolic recovery of the myocardium after ischemic arrest. We describe a hybrid of the off-pump and on-pump techniques to avoid ischemic arrest during coronary revascularization for this high-risk group.

The effects of propofol on lipid peroxidation and inflammatory response in elective coronary artery bypass grafting

OBJECTIVE

To determine whether the antioxidant and anti-inflammatory properties of propofol confer benefit in adult patients undergoing elective coronary artery bypass grafting.

DESIGN

Prospective, blinded, randomized, controlled clinical investigation.

SETTING

Single-center, university teaching hospital and academic research laboratory.

PARTICIPANTS

Twenty-one adult patients (11 control, 10 intervention) with chronic stable angina and normal ventricular function scheduled to undergo elective coronary artery bypass grafting.

INTERVENTIONS

All patients received a standardized fentanyl-isoflurane anesthetic. Fifteen minutes before reperfusion, patients in the intervention group received a target-controlled infusion of propofol, continued for 4 hours after cross-clamp release. Patients in the control group received saline administered in a similar fashion.

MEASUREMENTS

Serum concentration of malondialdehyde (MDA) (from systemic and coronary sinus blood); systemic concentrations of interleukins 4, 6, 8, and 10; and systemic leukocyte functions (respiratory burst, phagocytosis, and beta(2) integrin expression) were measured up to 36 hours after reperfusion.

RESULTS

A high serum malondialdehyde concentration was detected in the coronary sinus in control patients, 10 minutes after reperfusion; serum malondialdehyde was not detected in the coronary sinus at this time in patients who received propofol (41.4 [15.6-1,150] micromol/L v 0, p = 0.004). Interleukin-8 concentrations increased 2 and 4 hours after reperfusion in the control group. Interleukin-6 concentrations were greater in the control group than the propofol group 4 hours after clamp release (289.1 [165.2-561] rhog/mL v 153.2 (58.2-280.3) rhog/mL, respectively, p = 0.003). Mean dose of propofol was 31.7 mg/kg during the study period.

CONCLUSION

Clinically relevant concentrations of propofol may attenuate free radical-mediated and inflammatory components of myocardial reperfusion injury in patients undergoing elective coronary artery bypass graft surgery.

Impact of preoperative intravenous nitroglycerin on in-hospital outcomes after coronary artery bypass grafting for unstable angina

BACKGROUND

Intravenous nitroglycerin (NTG) is an effective therapy for unstable angina (UA), but it may induce endothelial dysfunction and impair vascular nitric oxide signaling. We sought to determine whether preoperative intravenous NTG administration alters in-hospital outcomes in patients undergoing coronary artery bypass grafting (CABG) for UA.

METHODS AND RESULTS

All in-hospital patients with Canadian Cardiovascular Society class IV angina who had isolated CABG between March 1995 and July 2002 at two Canadian centers were identified (n = 3976). Of these, 2506 were not receiving intravenous NTG and 1470 were receiving intravenous NTG at the time of CABG. Outcomes assessed were in-hospital mortality (IHM), intraoperative or postoperative aortic balloon pump use, perioperative myocardial infarction, prolonged (> or =24 hours) ventilation (p-vent), and a composite outcome, defined as any one or more of the above. Unadjusted IHM (5.9% vs 4.2%, P =.02), p-vent (22.2% vs 10.5%, P =.0001), and composite outcome (26.5% vs 15.2%, P =.0001) were higher in patients receiving intravenous NTG. Logistic regression showed that preoperative intravenous NTG was not an independent predictor of composite outcome (OR, 1.1; P =.49) or IHM (OR, 0.94; P =.69). Propensity score analysis was used to match two subgroups of patients (group 1, intravenous NTG, n = 1176; group 2, no intravenous NTG, n = 1176) on multiple factors. After adjustment with the propensity score, preoperative intravenous NTG use had no significant effect on any of the outcomes assessed.

CONCLUSIONS

Despite its potential to induce endothelial dysfunction and impair vascular nitric oxide signaling, preoperative intravenous NTG administration is not associated with altered in-hospital outcomes after CABG for UA.

Efficacy and safety of on-pump beating heart surgery for valvular disease

BACKGROUND

This study was conducted to assess the efficacy and applicability of on-pump beating heart valvular operations using retrograde coronary sinus perfusion.

METHODS

A prospective, randomized study was conducted. A total of 50 patients participated in this study after having been allocated to one of two groups. On-pump beating heart valvular operations using retrograde coronary sinus perfusion as myocardial protection were performed in 25 patients (beating heart procedure group: aortic = 8 patients, mitral = 15 patients, double = 2 patients). Twenty-five patients underwent conventional valvular operation using retrograde continuous warm blood cardioplegia (conventional procedure group: aortic = 9 patients; mitral = 13 patients; double = 3 patients). The remaining operative variables and early outcomes of these procedures were compared. In the beating heart procedure group, myocardial tissue oxygen was measured by near infrared spectroscopy, and partial oxygen pressure of coronary sinus perfusion was also measured.

RESULTS

The visual field of the on-pump beating heart was equal to that of conventional valvular operation, and technical accuracy was not compromised. In the beating heart procedure group, tissue oxygen saturation was maintained at 79% +/- 2%, and partial oxygen pressure of coronary sinus perfusion blood and returned blood were maintained at 383 +/- 29 mm Hg and 38 +/- 2 mm Hg, respectively. Postoperative peak creatine kinase-MB (measured every 3 hours postoperatively) and peak troponin T concentrations were significantly lower than those of conventional procedures (17.5 +/- 7.8 vs 32.1 +/- 9.3 IU/L and 0.12 +/- 0.04 vs 0.21 +/- 0.06 ng/mL, respectively; p < 0.05). There was no operative mortality and no major complications.

CONCLUSIONS

On-pump beating heart valvular operation is a good surgical option, and has advantages because conditions for the heart are more physiologic with beating tonus than with cardioplegia.

The potential of monoclonal antibodies to reduce reperfusion injury in myocardial infarction

Reperfusion injury is mediated, in part, by the accumulation of platelets and leucocytes in the microvasculature after reflow. These components of the blood pool form aggregates that can obstruct flow in small vessels. In addition, mediators released from leucocytes and platelets further damage the reperfused myocardium. A strategy to limit reperfusion injury exploits the important role of membrane-bound adhesion molecules that attach platelets and leucocytes to themselves and to the vascular endothelium. Monoclonal antibodies against specific adhesion receptors effectively eliminate the function of the receptor. The most widely investigated receptors are P-selectin, present on platelets and the endothelium, CD11/CD18, present on leucocytes, and the fibrinogen receptor on platelets. Numerous animal studies have strongly supported the use of these monoclonal antibodies to block adhesion receptors as adjunctive reperfusion therapy. However, recent human trials have yielded disappointing results.