"Polarizing" microplegia improves cardiac cycle efficiency after CABG for unstable angina

Whole Blood del Nido versus Cold Blood Microplegia in Adult Cardiac Surgery: A Propensity-Matched Analysis

Objectives  Few studies have evaluated the outcomes of whole blood microplegia in adult cardiac surgery. Our novel protocol includes removing the crystalloid portion and using the Quest Myocardial Protection System (MPS) for the delivery of del Nido additives in whole blood. This study sought to compare early and late clinical outcomes of whole blood del Nido microplegia (BDN) versus cold blood cardioplegia (CBC) following adult cardiac surgery. Materials and Methods  A total of 361 patients who underwent cardiac surgery using BDN were compared with a contemporaneous control group of 934 patients receiving CBC. Propensity matching yielded 289 BDN and 289 CBC patients. Chi-square analysis and Fisher's exact test were performed to compare preoperative, operative, and postoperative characteristics on the matched data. Primary outcome was operative mortality, and secondary outcomes included clinical outcomes such as stroke, cardiac arrest, and intra-aortic balloon pump use. The Kaplan-Meier method was used to compare actuarial survival between the two groups using a log-rank test. Results  After matching, preoperative characteristics and surgery type were similar between groups. Cardioplegia type did not affect the primary end point of operative mortality. The rate of postoperative intra-aortic balloon pump was lower in BDN patients compared with CBC patients (0 vs. 2%; p  = 0.01). There was no difference in late survival. Conclusion  Our novel protocol BDN was comparable with CBC, with similar clinical outcomes and no difference in operative mortality or actuarial survival. Further studies should evaluate the long-term outcomes of this technique.

Adenosine, lidocaine and Mg2+ update: teaching old drugs new tricks

If a trauma (or infection) exceeds the body's evolutionary design limits, a stress response is activated to quickly restore homeostasis. However, when the injury severity score is high, death is often imminent. The goal of this review is to provide an update on the effect of small-volume adenosine, lidocaine and Mg2+ (ALM) therapy on increasing survival and blunting secondary injury after non-compressible hemorrhagic shock and other trauma and infective/endotoxemic states. Two standout features of ALM therapy are: (1) resuscitation occurs at permissive hypotensive blood pressures (MAPs 50-60 mmHg), and (2) the drug confers neuroprotection at these low pressures. The therapy appears to reset the body's baroreflex to produce a high-flow, hypotensive, vasodilatory state with maintained tissue O2 delivery. Whole body ALM protection appears to be afforded by NO synthesis-dependent pathways and shifting central nervous system (CNS) control from sympathetic to parasympathetic dominance, resulting in improved cardiovascular function, reduced immune activation and inflammation, correction of coagulopathy, restoration of endothelial glycocalyx, and reduced energy demand and mitochondrial oxidative stress. Recently, independent studies have shown ALM may also be useful for stroke, muscle trauma, and as an adjunct to Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA). Ongoing studies have further shown ALM may have utility for burn polytrauma, damage control surgery and orthopedic surgery. Lastly, we discuss the clinical applications of ALM fluid therapy for prehospital and military far-forward use for non-compressible hemorrhage and traumatic brain injury (TBI).

Why are bleeding trauma patients still dying? Towards a systems hypothesis of trauma

Over the years, many explanations have been put forward to explain early and late deaths following hemorrhagic trauma. Most include single-event, sequential contributions from sympathetic hyperactivity, endotheliopathy, trauma-induced coagulopathy (TIC), hyperinflammation, immune dysfunction, ATP deficit and multiple organ failure (MOF). We view early and late deaths as a systems failure, not as a series of manifestations that occur over time. The traditional approach appears to be a by-product of last century’s highly reductionist, single-nodal thinking, which also extends to patient management, drug treatment and drug design. Current practices appear to focus more on alleviating symptoms rather than addressing the underlying problem. In this review, we discuss the importance of the system, and focus on the brain’s “privilege” status to control secondary injury processes. Loss of status from blood brain barrier damage may be responsible for poor outcomes. We present a unified Systems Hypothesis Of Trauma (SHOT) which involves: 1) CNS-cardiovascular coupling, 2) Endothelial-glycocalyx health, and 3) Mitochondrial integrity. If central control of cardiovascular coupling is maintained, we hypothesize that the endothelium will be protected, mitochondrial energetics will be maintained, and immune dysregulation, inflammation, TIC and MOF will be minimized. Another overlooked contributor to early and late deaths following hemorrhagic trauma is from the trauma of emergent surgery itself. This adds further stress to central control of secondary injury processes. New point-of-care drug therapies are required to switch the body’s genomic and proteomic programs from an injury phenotype to a survival phenotype. Currently, no drug therapy exists that targets the whole system following major trauma.

Immune dysfunction following severe trauma: A systems failure from the central nervous system to mitochondria

When a traumatic injury exceeds the body's internal tolerances, the innate immune and inflammatory systems are rapidly activated, and if not contained early, increase morbidity and mortality. Early deaths after hospital admission are mostly from central nervous system (CNS) trauma, hemorrhage and circulatory collapse (30%), and later deaths from hyperinflammation, immunosuppression, infection, sepsis, acute respiratory distress, and multiple organ failure (20%). The molecular drivers of secondary injury include damage associated molecular patterns (DAMPs), pathogen associated molecular patterns (PAMPs) and other immune-modifying agents that activate the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic stress response. Despite a number of drugs targeting specific anti-inflammatory and immune pathways showing promise in animal models, the majority have failed to translate. Reasons for failure include difficulty to replicate the heterogeneity of humans, poorly designed trials, inappropriate use of specific pathogen-free (SPF) animals, ignoring sex-specific differences, and the flawed practice of single-nodal targeting. Systems interconnectedness is a major overlooked factor. We argue that if the CNS is protected early after major trauma and control of cardiovascular function is maintained, the endothelial-glycocalyx will be protected, sufficient oxygen will be delivered, mitochondrial energetics will be maintained, inflammation will be resolved and immune dysfunction will be minimized. The current challenge is to develop new systems-based drugs that target the CNS coupling of whole-body function.

Normothermic blood polarizing versus depolarizing cardioplegia in a porcine model of cardiopulmonary bypass

OBJECTIVES

We have previously demonstrated beneficial cardiac protection with hypothermic polarizing cardioplegia compared to a hyperkalemic depolarizing cardioplegia. In this study, a porcine model of cardiopulmonary bypass was used to compare the protective effects of normothermic blood-based polarizing and depolarizing cardioplegia during cardiac arrest.

METHODS

Thirteen pigs were randomized to receive either normothermic polarizing (n = 8) or depolarizing (n = 5) blood-based cardioplegia. After initiation of cardiopulmonary bypass, normothermic arrest (34°C, 60 min) was followed by 60 min of on-pump and 90 min of off-pump reperfusion. Primary outcome was myocardial injury measured as arterial myocardial creatine kinase concentration. Secondary outcome was haemodynamic function and the energy state of the hearts.

RESULTS

During reperfusion, release of myocardial creatine kinase was comparable between groups (P = 0.36). In addition, most haemodynamic parameters showed comparable results between groups, but stroke volume (P = 0.03) was significantly lower in the polarizing group. Adenosine triphosphate levels were significantly (18.41 ± 3.86 vs 22.97 ± 2.73 nmol/mg; P = 0.03) lower in polarizing hearts, and the requirement for noradrenaline administration (P = 0.002) and temporary pacing (6 vs 0; P = 0.02) during reperfusion were significantly higher in polarizing hearts.

CONCLUSIONS

Under normothermic conditions, polarizing blood cardioplegia was associated with similar myocardial injury to depolarizing blood cardioplegia. Reduced haemodynamic and metabolic outcome and a higher need for temporary pacing with polarized arrest may be associated with the blood-based dilution of this solution.

Short-term outcome of adenosine-lidocaine-magnesium polarizing cardioplegia in humans

OBJECTIVES

Hyperkalaemic depolarized myocardial arrest is the cornerstone of myocardial protection, although some potassium-related cytotoxicity has been demonstrated. Polarized arrest has gained interest because of a reported better myocardial protection in preclinical studies. The goal of this study was to analyse the quality of myocardial protection and hospital outcome after normokalaemic adenosine-lidocaine-magnesium (ALM) blood polarizing cardioplegia, compared to hyperkalaemic blood Buckberg depolarizing cardioplegia, in elective routine adult cardiac surgery.

METHODS

One thousand consecutive elective adult cardiac patients [627 undergoing ALM-polarizing cardioplegia (ALM-POL) vs 373 Buckberg depolarized cardioplegia (BUCK-DEPOL)] who were operated on were analysed. Perioperative leakage of high-sensitivity troponin I (Hs-TnI), peripheral lactate, inotropic and vasoactive daily requirement [maximal vasoactive inotropic score (VISMAX)], hospital mortality and morbidity were collected and compared in the overall population and in the propensity score (PS) matched population (206 pairs).

RESULTS

A significantly lower leakage of Hs-TnI during hospitalization was detected in patients receiving ALM-POL versus those receiving BUCK-DEPOL (group time P < 0.001 for overall population and PS matched pairs). The maximum value of postoperative Hs-TnI was also lower after ALM-POL (P < 0.001 in both cohorts), and spontaneous recovery of sinus rhythm at aortic declamping was higher (P < 0.001 in favour of ALM-POL). Maximal VISMAX during hospitalization was significantly higher after BUCK-DEPOL in both cohorts (P = 0.019 for overall population; P = 0.031 for PS matched population), with significantly higher VISMAX on the day of surgery in BUCK-DEPOL PS matched patients (P = 0.042). No other significant differences in hospital morbidity and mortality were found.

CONCLUSIONS

Despite comparable short-term clinical outcomes, ALM-POL cardioplegia proved superior in terms of quality of myocardial protection compared to BUCK-DEPOL cardioplegia in elective routine adult cardiac surgery.

Cardioplegia between Evolution and Revolution: From Depolarized to Polarized Cardiac Arrest in Adult Cardiac Surgery

Despite current advances in perioperative care, intraoperative myocardial protection during cardiac surgery has not kept the same pace. High potassium cardioplegic solutions were introduced in the 1950s, and in the early 1960s they were soon recognized as harmful. Since that time, surgeons have minimized many of the adverse effects by lowering the temperature of the heart, lowering K⁺ concentration, reducing contact K⁺ time, changing the vehicle from a crystalloid solution to whole-blood, adding many pharmacological protectants and modifying reperfusion conditions. Despite these attempts, high potassium remains a suboptimalway to arrest the heart. We briefly review the historical advances and failures of finding alternatives to high potassium, the drawbacks of a prolonged depolarized membrane, altered Ca²⁺ intracellular circuits and heterogeneity in atrial-ventricular K⁺ repolarization during reanimation. Many of these untoward effects may be alleviated by a polarized membrane, and we will discuss the basic science and clinical experience from a number of institutions trialling different alternatives, and our institution with a non-depolarizing adenosine, lidocaine and magnesium (ALM) cardioplegia. The future of polarized arrest is an exciting one and may play an important role in treating the next generation of patients who are older, and sicker with multiple comorbidities and require more complex operations with prolonged cross-clamping times.

Efficacy of Whole-Blood Del Nido Cardioplegia Compared with Diluted Del Nido Cardioplegia in Coronary Artery Bypass Grafting: A Retrospective Monocentric Analysis of Pakistan

Background and Objectives: Cardioplegia is one of the most significant components used to protect the myocardium during cardiac surgery. There is a paucity of evidence regarding the utilization of whole-blood Del Nido cardioplegia (WB-DNC) on clinical outcomes in coronary artery bypass grafting (CABG). The purpose of this retrospective cross-sectional study is to compare the effectiveness of diluted (blood to crystalloid; 1:4) Del Nido cardioplegia (DNC) with WB-DNC in patients who underwent elective CABG in a tertiary care hospital in Lahore-Pakistan. Materials and Methods: This was a retrospective descriptive study conducted at the Department of Cardiovascular Surgery, King Edward Medical University, Lahore. The medical database of all consecutive patients admitted from January 2018 to March 2020 and who fulfilled the inclusion criteria were reviewed. Results: Out of 471 patients admitted during the study period, 450 underwent various elective cardiac surgeries. Out of 450, 321 patients (71.33%) were operated on for CABG. Only 234/321 (72.89%) CABG patients fulfilled our inclusion criteria; 120 (51.28%) patients received WB-DNC, while 114 (48.71%) patients were administered with DNC. The former group presented with better clinical outcomes compared with the latter in terms of lesser requirements of inotropic support, low degree of hemodilution, shorter in-hospital stay, improved renal function, and cost-effectiveness. Peak values of serum Troponin-T (Trop-T), creatine kinase-myocardial band (CK-MB) release, and activated clotting time (ACT) were also lower in the WB-DNC group compared with the DNC group. Conclusions: The WB-DNC conferred better myocardial protection, improved early clinical outcomes, and also proved to be economical for patients undergoing elective CABG compared with classical crystalloid cardioplegia solution.

Living in a Hostile World: Inflammation, New Drug Development, and Coronavirus

We present a brief history of the immune response and show that Metchnikoff's theory of inflammation and phagocytotic defense was largely ignored in the 20th century. For decades, the immune response was believed to be triggered centrally, until Lafferty and Cunningham proposed the initiating signal came from the tissues. This shift opened the way for Janeway's pattern recognition receptor theory, and Matzinger's danger model. All models failed to appreciate that without inflammation, there can be no immune response. The situation changed in the 1990s when cytokine biology was rapidly advancing, and the immune system's role expanded from host defense, to the maintenance of host health. An inflammatory environment, produced by immune cells themselves, was now recognized as mandatory for their attack, removal and repair functions after an infection or injury. We explore the cellular programs of the immune response, and the role played by cytokines and other mediators to tailor the right response, at the right time. Normally, the immune response is robust, self-limiting and restorative. However, when the antigen load or trauma exceeds the body's internal tolerances, as witnessed in some COVID-19 patients, excessive inflammation can lead to increased sympathetic outflows, cardiac dysfunction, coagulopathy, endothelial and metabolic dysfunction, multiple organ failure and death. Currently, there are few drug therapies to reduce excessive inflammation and immune dysfunction. We have been developing an intravenous (IV) fluid therapy comprising adenosine, lidocaine and Mg2+ (ALM) that confers a survival advantage by preventing excessive inflammation initiated by sepsis, endotoxemia and sterile trauma. The multi-pronged protection appears to be unique and may provide a tool to examine the intersection points in the immune response to infection or injury, and possible ways to prevent secondary tissue damage, such as that reported in patients with COVID-19.

Six-month prognostic impact of hemodynamic profiling by short minimally invasive monitoring after cardiac surgery

Introduction: Studies have shown that a hemodynamic-guided therapy improves the post operative outcomes of high-risk patients.This study, evaluated if a short period through minimally invasive hemodynamic monitoring, pressure recording analytical method (PRAM), on admission to a post-cardiac surgery step-down unit (SDU), may identify patients at higher risk of 6-month adverse events after cardiac surgery. Methods: From December 2016-May 2017,173 patients were admitted in SDU within 24-48 hours of major cardiac surgery procedure, and submitted to clinical, laboratoristic and echocardiographic evaluation and a 1-hour PRAM recording to obtain a "biohumoral snapshot" of individual patient's.156 173 patients (17 patients were lost at follow-up) were phone interviewed six months after surgery,to evaluate, as a composite end-point, the adverse events during follow-up. A multivariable logistic regression analysis was used to identify a model clinical-biohumoral (CBM) and clinical-biohumoral hemodynamics (CBHM). Results: No data from past clinical history and no conventional risk score (EuroScore II, STS score)independently predicted the risk of 6-month major events in our study. The risk of adverse events at six-month follow-up was directly related, in the CBM, to sustained post-operative cardiac arrhythmias, higher values of NT-proBNP and of arterial pH; inversely related to values of hs-C-reactive protein (hs-CRP) and, in the CBHM, to low values of cardiac cycle efficiency (CCE) and dP/dt_max. Conclusion: Our study although limited by its observational nature and by the limited number of patients enrolled, showed that a short period of minimally invasive hemodynamic monitoring increased the accuracy to identify patients at major risk of mid-term events after cardiac surgery.

Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review

For patients undergoing cardiopulmonary bypass, myocardial protection is a key for successful recovery and improved outcomes following cardiac surgery that requires cardiac arrest. Different solutions, components and modes of delivery have evolved over the last few decades to optimise myocardial protection. These include cold and warm and blood and crystalloid solution through antegrade, retrograde or combined cardioplegia delivery approach. However, each method has its own advantages and disadvantages, posing a challenge to establish a gold-standard cardioplegic solution with an optimised mode of delivery for enhanced myocardial protection during cardiac surgery. The aim of this review is to provide a brief history of the development of cardioplegia, explain the electrophysiological concepts behind myocardial protection in cardioplegia, analyse the current literature and summarise existing evidence that warrants the use of varying cardioplegic techniques. We provide a comprehensive and comparative overview of the effectiveness of each technique in achieving optimal cardioprotection and propose novel techniques for optimising myocardial protection in the future.

Trauma of major surgery: A global problem that is not going away

Globally, a staggering 310 million major surgeries are performed each year; around 40 to 50 million in USA and 20 million in Europe. It is estimated that 1–4% of these patients will die, up to 15% will have serious postoperative morbidity, and 5–15% will be readmitted within 30 days. An annual global mortality of around 8 million patients places major surgery comparable with the leading causes of death from cardiovascular disease and stroke, cancer and injury. If surgical complications were classified as a pandemic, like HIV/AIDS or coronavirus (COVID-19), developed countries would work together and devise an immediate action plan and allocate resources to address it. Seeking to reduce preventable deaths and post-surgical complications would save billions of dollars in healthcare costs. Part of the global problem resides in differences in institutional practice patterns in high- and low-income countries, and part from a lack of effective perioperative drug therapies to protect the patient from surgical stress. We briefly review the history of surgical stress and provide a path forward from a systems-based approach. Key to progress is recognizing that the anesthetized brain is still physiologically ‘awake’ and responsive to the sterile stressors of surgery. New intravenous drug therapies are urgently required after anesthesia and before the first incision to prevent the brain from switching to sympathetic overdrive and activating secondary injury progression such as hyperinflammation, coagulopathy, immune activation and metabolic dysfunction. A systems-based approach targeting central nervous system-mitochondrial coupling may help drive research to improve outcomes following major surgery in civilian and military medicine.

Prognostic value of cardiac cycle efficiency in children undergoing cardiac surgery: a prospective observational study

BACKGROUND

Cardiac cycle efficiency (CCE) derived from a pressure-recording analytical method is a unique parameter to assess haemodynamic performance from an energetic view. This study investigated changes of CCE according to an anatomical diagnosis group, and its association with early postoperative outcomes in children undergoing cardiac surgery.

METHODS

Ninety children were included with a ventricular septal defect (VSD; n=30), tetralogy of Fallot (TOF; n=40), or total anomalous pulmonary venous connection (TAPVC; n=20). CCE along with other haemodynamic parameters, was recorded from anaesthesia induction until 48 h post-surgery. Predictive CCE (CCE_p) was defined as the average of CCE at post-modified ultrafiltration and CCE at the end of surgery. The relationship between CCE and early outcomes was assessed by the comparison between the high-CCE_p group (CCE_p ≥75th centile) and the low-CCE_p group (CCE_p ≤25th centile).

RESULTS

There was a significant time × diagnostic group interaction effect in the trend of CCE. Compared with the high-CCE_p group (n=23), the low-CCE_p group (n=22) required more inotropics post-surgery, had higher lactate concentrations at 8 and 24 h post-surgery, a longer intubation time and longer ICU stay, and higher frequency of peritoneal fluid.

CONCLUSIONS

Perioperative changes of CCE vary according to anatomical diagnosis in children undergoing cardiac surgery. Children with TOF have an unfavourable trend of CCE compared with children with VSD or TAPVC. A decline in CCE is associated with adverse early postoperative outcomes.

CLINICAL TRIAL REGISTRATION

ChiCTR1800014996.

Adenosine, Lidocaine, and Magnesium Support a High Flow, Hypotensive, Vasodilatory State With Improved Oxygen Delivery and Cerebral Protection in a Pig Model of Noncompressible Hemorrhage

BACKGROUND

Noncompressible hemorrhage is the leading cause of preventable death in military and civilian trauma. Our aim was to examine the effect of adenosine, lidocaine, and magnesium (Mg²⁺; ALM) on cardiovascular and cerebral function in a porcine hepatic hemorrhage model.

MATERIALS AND METHODS

Pigs (59.1 ± 0.34 kg) were anesthetized, instrumented, and randomly assigned into sham (n = 6), saline controls (n = 10) or ALM (n = 10) groups before laparoscopic liver resection. After 30 min, groups received 4 mL/kg 3% NaCl ± ALM bolus (Phase 1) followed 60 min later with 3 mL/kg/h 0.9% NaCl ± ALM drip (4 h; Phase 2), then transfusion. Hemodynamics, carotid artery flow, and intracranial pressure were measured continuously. Microdialysis samples were analyzed for metabolites.

RESULTS

Saline controls had 20% mortality (mean survival time: 307 ± 38 min) with no ALM deaths over 6 h. Bolus administration increased mean arterial pressure (MAP) in both groups, and drip led to further increases to 62 ± 10 mmHg in controls compared with a steady fall to 47 ± 8 mmHg in ALM group at 240 min. The lower MAP was associated with a dramatic fall in systemic vascular resistance and improved oxygen delivery. ALM drip significantly increased cardiac output and stroke volume with lower dP/dt_Min, indicating a less stiff heart. ALM drip also significantly decreased cerebral perfusion pressure, reduced cerebral oxygen consumption (28%), and reduced brain glycerol (60%), lactate (47%), and relative expression of hypoxia-inducible factor (38%) compared with saline controls.

CONCLUSIONS

ALM therapy improved cardiac function and oxygen delivery by lowering systemic vascular resistance after noncompressible hemorrhage. ALM also appeared to protect the brain at hypotensive MAPs with significantly lower cerebral perfusion pressure, lower O₂ consumption, and significantly lower cortical lactate and glycerol levels compared to saline controls.

St Thomas' Hospital polarizing blood cardioplegia improves hemodynamic recovery in a porcine model of cardiopulmonary bypass

OBJECTIVE

Cardiac surgery demands highly effective cardioprotective regimens. We previously demonstrated improved cardioprotection with "polarized" compared with "depolarized" arrest. This study uses a clinically relevant porcine model of cardiopulmonary bypass to compare the efficacy of blood-based St Thomas' Hospital polarizing cardioplegia (STH-Pol-B) with blood-based St Thomas' Hospital hyperkalemic cardioplegia (STH2-B).

METHODS

Pigs were monitored and subjected to normothermic cardiopulmonary bypass, cardiac arrest via antegrade cold (4°C) blood cardioplegia (STH2-B, control group: n = 6 or STH-Pol-B, study group: n = 7), and global ischemia (60 minutes) followed by on-pump reperfusion (60 minutes) and subsequent off-pump reperfusion (90 minutes). At termination, tissue samples were taken for analysis of high-energy phosphates, ultrastructure, and microRNAs. The primary endpoint of this study was creatine kinase-muscle/brain release during reperfusion.

RESULTS

Creatine kinase-muscle/brain was comparable in both groups. After pigs were weaned from cardiopulmonary bypass, hemodynamic parameters such as mean arterial pressure (P = .007), left ventricular systolic pressure (P < .001), external heart work (P = .012), stroke volume (P = .015), as well as dp/dt_max (P = .027), were improved with polarizing cardioplegia. Wedge pressure was significantly lower in the study group (P < .01). Energy charge was comparable between groups. MicroRNA-708-5p was significantly lower (P = .019) and microRNA-122 expression significantly (P = .046) greater in STH-Pol-B hearts.

CONCLUSIONS

Polarized cardiac arrest offers similar myocardial protection and enhances functional recovery in a porcine model of cardiopulmonary bypass. Differential expression of microRNAs may indicate possible new ischemia-reperfusion markers. These results confirm the noninferiority and potential of polarized versus depolarized arrest.

Mitochondrial Dysfunction in Cardiac Surgery

Mitochondria are key to the cellular response to energetic demand, but are also vital to reactive oxygen species signaling, calcium hemostasis, and regulation of cell death. Cardiac surgical patients with diabetes, heart failure, advanced age, or cardiomyopathies may have underlying mitochondrial dysfunction or be more sensitive to perioperative mitochondrial injury. Mitochondrial dysfunction, due to ischemia/reperfusion injury and an increased systemic inflammatory response due to exposure to cardiopulmonary bypass and surgical tissue trauma, impacts myocardial contractility and predisposes to arrhythmias. Strategies for perioperative mitochondrial protection and recovery include both well-established cardioprotective protocols and targeted therapies that remain under investigation.

Blood cardioplegia for cardiac surgery in acute myocardial infarction: rat experiments with two widely used solutions

OBJECTIVES

Blood cardioplegia (BCP) can be used in different ways to protect the heart from ischaemia-reperfusion injury during cardiac surgery. Because there could be differences between warm and cold intermittent cardioplegia with or without warm reperfusion, we investigated the influence of 2 blood cardioplegia solutions on cardiac function, metabolism and infarct size in stable and infarcted rat hearts.

METHODS

The hearts of 32 male Wistar rats were excised and inserted into a blood-perfused isolated heart apparatus. In 16 hearts, an acute myocardial infarction was induced by ligation of the left anterior descending coronary artery at least 30 min before aortic clamping. After aortic clamping, either Calafiore or Buckberg BCP was administered. During reperfusion, coronary blood flow, left ventricular developed pressure and dp/dt max were recorded, and oxygen consumption and lactate production were determined. The infarct size after 90 min of reperfusion was measured by triphenyl tetrazolium chloride staining. The hearts of rats without infarction were investigated using transmission electron microscopy.

RESULTS

In hearts without infarction, haemodynamic recovery was similar for Calafiore and Buckberg solutions: left ventricular developed pressure [Cala 62% of baseline (BL), Buck 58% BL] and dp/dt max (Cala 83% BL, Buck 89% BL). Coronary flow, which was slightly less in infarcted hearts, also recovered similarly after the administration of the 2 BCP solutions (Cala 65% BL, Buck 68% BL). During reperfusion, lactate production was similar (Cala 0.85 ml/min, Buck 1.0 ml/min), and the cellular oedema index and mitochondrial swelling were comparable between the 2 groups. In hearts with infarction, left ventricular developed pressure (Cala 58% BL, Buck 56% BL) and dp/dt max (Cala 79% BL, Buck 72% BL) showed similar recovery for reperfusion with Calafiore or Buckberg BCP. In addition, coronary flow recovered similarly (Cala 54% BL, Buck 57% BL). During reperfusion, myocardial oxygen consumption was lower in the Cala (67% BL) than in the Buck (82% BL) group, but lactate production was similar between the Cala (1.1 ml/min) and the Buck (1.1 ml/min) groups. Myocardial infarct size was also similar in the Cala group (24%) and in the Buck group (26%).

CONCLUSIONS

In stable perfused rat hearts and in an in vitro model of acute myocardial infarction, the 2 BCP solutions offer equally good myocardial protection.

Does the type of cardioplegia used during valve surgery influence operative nadir hematocrit and transfusion requirements?

INTRODUCTION

Myocardial protection is performed using diverse cardioplegic (CP) solutions with various combinations of chemical and blood constituents. Newer CP formulations that extend ischemic intervals may require greater asanguineous volume, contributing to hemodilution.

METHODS

We evaluated intraoperative hemodilution and red blood cell (RBC) transfusion rates among three common CP solutions during cardiac valve surgery. Data from 5,830 adult cardiac primary valve procedures where either four-to-one blood CP (4:1), del Nido solution (DN) or microplegia (MP) was used at 173 United States surgical centers. The primary outcome was the nadir hematocrit (Hct) during cardiopulmonary bypass (CPB), with a secondary outcome of total units of RBC transfused intraoperatively. Outcomes were assessed using mixed-effects regression, with controls for patient size, age, first Hct in the operating room, ultrafiltration volume, net bypass circuit priming volume, anesthesia and perfusion asanguineous volumes, cross-clamp and total procedure times, procedure type, reoperation, hospital, surgeon and twelve other patient and procedural variables.

RESULTS

A total of 2,641 patients received 4:1 (45.3%), 1,864 received DN (32.0%) and 1,325 received MP (22.7%). There were only slight differences in the central tendency (mean (SD)) for crude nadir Hct on CPB: 4:1, 25.5 (4.5), DN, 26.0 (4.6) and MP, 26.5 (4.7). After controlling for numerous operative and patient characteristics, the regression-adjusted estimate of the nadir Hct on CPB for MP was 26.2%, compared to 25.7% for 4:1 and 25.7% for DN; differences between MP and the other methods were statistically significant (p<0.01). Unadjusted mean RBC units transfused per patient was very similar across the groups (4:1, 2.2; MP, 2.3; DN, 2.4). Regression-adjusted estimates for the number of units of RBC transfused intraoperatively showed no statistically significant differences between CP methods.

CONCLUSIONS

In patients undergoing cardiac valve surgery, the type of CP did not have a strong clinical impact on hemodilution or transfusion. Choice of a myocardial preservation solution can be made independently of its effect on intraoperative Hct.

Clinical and economic benefits of advanced microplegia delivery system in cardiac surgery: evidence from 250 hospitals

AIM

Determine the impact of a second generation microplegia delivery system (MPS2) compared with traditional cardioplegia. Materials &  methods: Multivariable difference-in-differences analysis using fixed effects was performed for each outcome: adverse event (AE) composite, total visit cost, medication cost, length of stay (LOS) and  intensive care unit (ICU) days.

RESULTS

A 2.25% absolute risk reduction in AE composite was found with MPS2 compared with traditional cardioplegia, which equates to relative risk reduction of 5.25%. Significant reductions in LOS and ICU days (0.1 α level). Per case reduction of US$1231 total visit and US$192 medication costs were found in MPS2 hospitals.

CONCLUSION

For hospitals with MPS2, significant reductions were seen in AEs, LOS and ICU days, which lead to reductions in total visit and medication costs.

Cardiac kinematic parameters computed from video of in situ beating heart

Mechanical function of the heart during open-chest cardiac surgery is exclusively monitored by echocardiographic techniques. However, little is known about local kinematics, particularly for the reperfused regions after ischemic events. We report a novel imaging modality, which extracts local and global kinematic parameters from videos of in situ beating hearts, displaying live video cardiograms of the contraction events. A custom algorithm tracked the movement of a video marker positioned ad hoc onto a selected area and analyzed, during the entire recording, the contraction trajectory, displacement, velocity, acceleration, kinetic energy and force. Moreover, global epicardial velocity and vorticity were analyzed by means of Particle Image Velocimetry tool. We validated our new technique by i) computational modeling of cardiac ischemia, ii) video recordings of ischemic/reperfused rat hearts, iii) videos of beating human hearts before and after coronary artery bypass graft, and iv) local Frank-Starling effect. In rats, we observed a decrement of kinematic parameters during acute ischemia and a significant increment in the same region after reperfusion. We detected similar behavior in operated patients. This modality adds important functional values on cardiac outcomes and supports the intervention in a contact-free and non-invasive mode. Moreover, it does not require particular operator-dependent skills.

Cardiac kinematic parameters computed from video of in situ beating heart

Mechanical function of the heart during open-chest cardiac surgery is exclusively monitored by echocardiographic techniques. However, little is known about local kinematics, particularly for the reperfused regions after ischemic events. We report a novel imaging modality, which extracts local and global kinematic parameters from videos of in situ beating hearts, displaying live video cardiograms of the contraction events. A custom algorithm tracked the movement of a video marker positioned ad hoc onto a selected area and analyzed, during the entire recording, the contraction trajectory, displacement, velocity, acceleration, kinetic energy and force. Moreover, global epicardial velocity and vorticity were analyzed by means of Particle Image Velocimetry tool. We validated our new technique by i) computational modeling of cardiac ischemia, ii) video recordings of ischemic/reperfused rat hearts, iii) videos of beating human hearts before and after coronary artery bypass graft, and iv) local Frank-Starling effect. In rats, we observed a decrement of kinematic parameters during acute ischemia and a significant increment in the same region after reperfusion. We detected similar behavior in operated patients. This modality adds important functional values on cardiac outcomes and supports the intervention in a contact-free and non-invasive mode. Moreover, it does not require particular operator-dependent skills.

Dose-response relationship between dietary magnesium intake and cardiovascular mortality: A systematic review and dose-based meta-regression analysis of prospective studies

BACKGROUND

Although epidemiology studies have reported the relationship, including a dose-response relationship, between dietary magnesium intake and risk of cardiovascular disease (CVD), the risk for CVD mortality is inconclusive and the evidence for a dose-response relationship has not been summarized.

OBJECTIVE

We conducted a systematic review and meta-analysis of prospective studies to summarize the evidence regarding the association of dietary magnesium intake with risk of CVD mortality and describe their dose-response relationship.

DESIGN

We identified relevant studies by searching major scientific literature databases and grey literature resources from their inception to August 2015, and reviewed references lists of retrieved articles. We included population-based studies that reported mortality risks, i.e. relative risks (RRs), odds ratios (ORs) or hazard ratios (HRs) of CVD mortality or cause-specific CVD death. Linear dose-response relationships were assessed using random-effects meta-regression. Potential nonlinear associations were evaluated using restricted cubic splines.

RESULTS

Out of 3002 articles, 9 articles from 8 independent studies met the eligibility criteria. These studies comprised 449,748 individuals and 10,313 CVD deaths. Compared with the lowest dietary magnesium consumption group in the population, the risk of CVD mortality was reduced by 16% in women and 8% in men. No significant linear dose-response relationship was found between increment in dietary magnesium intake and CVD mortality across all the studies. After adjusting for age and BMI, the risk of CVD mortality was reduced by 24-25% per 100mg/d increment in dietary magnesium intake in women of all the participants and in all the US participants.

CONCLUSION

Although the combined data confirm the role of dietary magnesium intake in reducing CVD mortality, the dose-response relationship was only found among women and in US population.

Addressing the Global Burden of Trauma in Major Surgery

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

Is microplegia really superior to standard blood cardioplegia? The results from a meta-analysis

Background:

Microplegia (whole blood cardioplegia with reduced volume) retains all the advantages of blood cardioplegia (such as superior oxygen-carrying capacity, better osmotic properties and antioxidant capability, etc.) without the potential disadvantages of hemodilution (such as myocardial edema). We sought to perform a systematic review and meta-analysis to compare microplegia and standard blood cardioplegia on the cardioprotective effects for patients undergoing coronary artery bypass grafting (CABG).

Methods:

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched for relevant controlled trials published in English, from their inception up to May 15th, 2013. Data on low output syndrome, spontaneous return to sinus rhythm, volume of cardioplegia and perioperative myocardial infarction were analyzed.

Results:

Five studies, totaling 296 patients, were included out of 77 retrieved citations. The microplegia group used less volume of cardioplegia (WMD, -514.79 ml, 95%CI: -705.37 ml to -324.21 ml) when compared with the standard blood cardioplegia group. There were no statistical differences in the incidence of low output syndrome (RR, 0.95, 95%CI: 0.55 to 1.62), spontaneous return to sinus rhythm (RR, 1.64, 95%CI: 0.61 to 4.41) and perioperative myocardial infarction (RR, 0.62, 95%CI: 0.19 to 2.08).

Conclusions:

Microplegia was associated with less volume of cardioplegia, whereas the incidence of spontaneous return to sinus rhythm and perioperative myocardial infarction were similar, but large controlled randomized trials are still needed to confirm this.

Adenosine regulation of the immune response initiated by ischemia reperfusion injury

It is clinically established that adenosine has negative chronotropic, antiarrhythmic effects and reduces arterial blood pressure. Adenosine addition to cardioplegic solutions used in cardiac operations is clinically well tolerated and has been shown to improve myocardial protection in several studies. However, the mechanism of action remains unclear. Therefore, it is important to define the effect of adenosine on the inflammatory cascade as immune cell activation occurs early during ischemia reperfusion injury. Adenosine appears to mediate the initial steps of the inflammatory cascade via its four G-coupled protein receptors: A1, A2A, A2B, and A3, expressed on neutrophils, lymphocytes and macrophages. The adenosine receptor isotype dictates the immune response. More specifically, the A1 and A3 receptors stimulate a pro-inflammatory immune response whereas the A2A and A2B are immunosuppressive. As the adenosine receptors are important for cardiac pre-conditioning and post-conditioning, adenosine may regulate the inflammatory responses initiated during ischemia-mediated immune injury related to myocardial protection.

Does magnesium-supplemented cardioplegia reduce cardiac injury? A meta-analysis of randomized controlled trials

BACKGROUND

Magnesium is often used to supplement cardioplegic solutions during cardiopulmonary bypass due to its cardioprotective effect during ischemia and reperfusion. The aim of this meta-analysis was to evaluate the effects of magnesium-supplemented cardioplegia versus an inactive (placebo) control cardioplegia on reducing cardiac injury after cardiac arrest surgery, as found by randomized, controlled trials.

METHODS

The Medline, Cochrane Library, and Chinese literature databases (CJFD, CBM, CSJD, Wanfang) were comprehensively searched for reports of randomized, controlled trials (RCTs) evaluating magnesium-supplemented cardioplegic solutions. The clinical parameters and outcomes of interest were the incidence of postoperative low cardiac output, auto-rebeating rate, ICU stay length, new onset postoperative atrial fibrillation, peak value of CK-MB (and/or cTnI), incidence of myocardial infarction, and in-hospital mortality.

RESULTS

Ten trials, with a total of 1214 patients, were included. The frequency of low cardiac output, inotropic utilization, and myocardial infarction, as well as auto-rebeating rate, length of ICU stay and in-hospital mortality, were similar between the two groups. There was a marginal reduction in the incidence of new-onset postoperative atrial fibrillation in the magnesium-supplemented cardioplegia group.

CONCLUSIONS

The advantage of magnesium-supplemented cardioplegia, compared with cardioplegia without magnesium, remains unconvincing based on the current evidence. The decision to add magnesium to the cardioplegic solution to a patient undergoing cardiac arrest surgery should be carefully considered.

Adenosine, lidocaine and Mg2+ improves cardiac and pulmonary function, induces reversible hypotension and exerts anti-inflammatory effects in an endotoxemic porcine model

Introduction

The combination of Adenosine (A), lidocaine (L) and Mg²⁺ (M) (ALM) has demonstrated cardioprotective and resuscitative properties in models of cardiac arrest and hemorrhagic shock. This study evaluates whether ALM also demonstrates organ protective properties in an endotoxemic porcine model.

Methods

Pigs (37 to 42 kg) were randomized into: 1) Control (n = 8) or 2) ALM (n = 8) followed by lipopolysaccharide infusion (1 μg∙kg^-1∙h^-1) for five hours. ALM treatment consisted of 1) a high dose bolus (A (0.82 mg/kg), L (1.76 mg/kg), M (0.92 mg/kg)), 2) one hour continuous infusion (A (300 μg∙kg^-1 ∙min^-1), L (600 μg∙kg^-1 ∙min^-1), M (336 μg∙kg^-1 ∙min^-1)) and three hours at a lower dose (A (240∙kg^-1∙min^-1), L (480 μg∙kg^-1∙min^-1), M (268 μg∙kg^-1 ∙min^-1)); controls received normal saline. Hemodynamic, cardiac, pulmonary, metabolic and renal functions were evaluated.

Results

ALM lowered mean arterial pressure (Mean value during infusion period: ALM: 47 (95% confidence interval (CI): 44 to 50) mmHg versus control: 79 (95% CI: 75 to 85) mmHg, P <0.0001). After cessation of ALM, mean arterial pressure immediately increased (end of study: ALM: 88 (95% CI: 81 to 96) mmHg versus control: 86 (95% CI: 79 to 94) mmHg, P = 0.72). Whole body oxygen consumption was significantly reduced during ALM infusion (ALM: 205 (95% CI: 192 to 217) ml oxygen/min versus control: 231 (95% CI: 219 to 243) ml oxygen/min, P = 0.016). ALM treatment reduced pulmonary injury evaluated by PaO₂/FiO₂ ratio (ALM: 388 (95% CI: 349 to 427) versus control: 260 (95% CI: 221 to 299), P = 0.0005). ALM infusion led to an increase in heart rate while preserving preload recruitable stroke work. Creatinine clearance was significantly lower during ALM infusion but reversed after cessation of infusion. ALM reduced tumor necrosis factor-α peak levels (ALM 7121 (95% CI: 5069 to 10004) pg/ml versus control 11596 (95% CI: 9083 to 14805) pg/ml, P = 0.02).

Conclusion

ALM infusion induces a reversible hypotensive and hypometabolic state, attenuates tumor necrosis factor-α levels and improves cardiac and pulmonary function, and led to a transient drop in renal function that was reversed after the treatment was stopped.

Evidence-based medicine and myocardial protection — where is the evidence?

Objective:

Myocardial protection with cardioplegia is an integral component of most cardiac surgical procedures, providing protection of the heart by limiting metabolic activity and increasing the myocardium’s capacity to withstand ischemia for prolonged periods of time. Cardioplegia has greatly affected the landscape of cardiothoracic surgery since its introduction in the 1960s, but, to this day, there continues to be a debate over what the ideal cardioplegic solution should be. The goal of this analysis is to describe current practices in cardioplegia and to point out the lack of quality human research and subsequent publications that prevent best practices from being utilized.

Methods:

This study is a systematic review of journal publications pertaining to the composition of commonly used cardioplegic solutions. Four main types of cardioplegia were assessed to give a narrower field of examination; specifically, microplegia, del Nido, Custodiol HTK, and 4:1 blood cardioplegia. Other combinations of cardioplegia, including St. Thomas’s Solution and the University of Wisconsin (UW) Solution, were considered when applicable according to the context of the publication being reviewed. Factors being assessed consisted of scientific validity, nature of the test subject (isolated organ vs. animal vs. human studies), experimental setup (retrospective trials vs. randomized clinical trials) and patient outcomes.

Results:

There are very few randomized clinical trials with human subjects comparing commonly used cardioplegic solutions. Numerous retrospective studies exist, but often show similar intraoperative and postoperative outcomes between the solutions. Some solutions, del Nido cardioplegia in particular, were found to have few or no significant human trials to back the rigor required in such a highly specialized field as cardiovascular surgery. A wide variation in the types of surgeries and primary outcomes were included in the publications, so it is difficult to perform an accurate systematic review of the topic.

Conclusion:

Uniform variables among different studies would be preferable for analysis of this topic; thus, it is the researchers’ recommendation that the collection of multicenter data be undertaken in order to more fully answer this research question. Comparative effectiveness studies to associate commonly used solutions are needed. Without this research, surgeon preference remains the primary determining factor for deciding which cardioplegic solution to use. Cardioplegia selection should rely more on higher scientific research, using evidenced-based medicine and ranking of clinical studies.

Pulmonary function after hemorrhagic shock and resuscitation in a porcine model

BACKGROUND

Hemorrhagic shock may trigger an inflammatory response and acute lung injury. The combination adenosine, lidocaine (AL) plus Mg(2+) (ALM) has organ-protective and anti-inflammatory properties with potential benefits in resuscitation.The aims of this study were to investigate: (1) pulmonary function and inflammation after hemorrhagic shock; (2) the effects of ALM/AL on pulmonary function and inflammation.

METHODS

Pigs (38 kg) were randomized to: sham + saline (n = 5); sham + ALM/AL (n = 5); hemorrhage control (n = 11); and hemorrhage + ALM/AL (n = 9). Hemorrhage animals bled to a mean arterial pressure (MAP) of 35 mmHg for 90 min, received resuscitation with Ringer's acetate and 20 ml of 7.5% NaCl with ALM to a minimum MAP of 50 mmHg, after 30 min shed blood and 0.9% NaCl with AL were infused. Hemorrhage controls did not receive ALM/AL. Primary endpoints were pulmonary wet/dry ratio, PaO2 /FiO2 ratio (partial pressure of arterial oxygen to the fraction of inspired oxygen), cytokine and protein measurements in bronchoalveolar lavage fluid (BALF) and lung tissue, neutrophil invasion and blood flow in lung tissue.

RESULTS

In the hemorrhage groups, wet/dry ratio increased significantly compared with the sham groups. PaO2 /FiO2 ratio decreased during shock but normalized after resuscitation. BALF did not indicate significant pulmonary inflammation, oxidative stress or increased permeability. Intervention with ALM caused a temporary increase in pulmonary vascular resistance and reduced urea diffusion across the alveolar epithelia, but had no effect on wet/dry ratio.

CONCLUSION

Hemorrhagic shock and resuscitation did not cause acute lung injury or pulmonary inflammation. The question whether ALM/AL has the potential to attenuate acute lung injury is unanswered.

Organ protective mechanisms common to extremes of physiology: a window through hibernation biology

Supply and demand relationships govern survival of animals in the wild and are also key determinants of clinical outcomes in critically ill patients. Most animals' survival strategies focus on the supply side of the equation by pursuing territory and resources, but hibernators are able to anticipate declining availability of nutrients by reducing their energetic needs through the seasonal use of torpor, a reversible state of suppressed metabolic demand and decreased body temperature. Similarly, in clinical medicine the majority of therapeutic interventions to care for critically ill or trauma patients remain focused on elevating physiologic supply above critical thresholds by increasing the main determinants of delivery of oxygen to the tissues (cardiac output, perfusion pressure, hemoglobin concentrations, and oxygen saturation), as well as increasing nutritional support, maintaining euthermia, and other general supportive measures. Techniques, such as induced hypothermia and preconditioning, aimed at diminishing a patient's physiologic requirements as a short-term strategy to match reduced supply and to stabilize their condition, are few and underutilized in clinical settings. Consequently, comparative approaches to understand the mechanistic adaptations that suppress metabolic demand and alter metabolic use of fuel as well as the application of concepts gleaned from studies of hibernation, to the care of critically ill and injured patients could create novel opportunities to improve outcomes in intensive care and perioperative medicine.

The Bellamy challenge: it's about time

In 1984, Col. Ronald Bellamy launched a worldwide challenge to develop a new resuscitation fluid to aid survival after catastrophic blood loss on the battlefield. In 1996, after careful compromise among need, cube weight and efficacy, the US military and later coalition forces adopted 6% hetastarch (HES) fluids for early resuscitation. In the intervening years, evidence has amassed indicating that the HES fluids may not be safe, and in June 2013 the US Food and Drug Administration issued a warning that HES solutions should not be used to treat patients with hypovolaemia or the critically ill. We review the unique challenges of early battlefield resuscitation, why the 'Bellamy challenge' remains open and discuss a number of forward-looking strategies that may help to solve the problem. The first two pillars of resuscitation that we believe have not been adequately addressed are rescuing and stabilising the heart (and brain) and the vascular system. The 'ideal' resuscitation fluid needs to nurture the heart and body slowly back to health, and not 'shock' it a second time with unnatural colloids or large volumes of unphysiological saline-based solutions.

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.

Myocardial protection in cardiac surgery: a historical review from the beginning to the current topics

Myocardial protection has become an essential adjunctive measure in cardiac surgery for a couple of decades, because since the 1950s, the methods of cardioprotection (cardioplegic solutions and related procedures) have been improved by the mechanism of myocardial ischemia/reperfusion-induced damage being unveiled through the untiring efforts of researchers and clinicians. The concept of myocardial protection in cardiac surgery was proposed along with introduction of hypothermic crystalloid potassium cardioplegia in the beginning and has been diversified by pharmacological additives, blood cardioplegia, temperature modulation (warm; tepid), retrograde cardioplegia, controlled reperfusion, integrated cardioplegia, and pre-and postconditioning. This historical review summarized experimental and clinical studies dealing with the methods and results of myocardial protection in cardiac surgery, introducing the newly developed concepts for the last decade and the current topics.