Cardioplegic Solution Research Articles

Mannitol Is Associated with Less Postoperative Delirium after Aortic Valve Surgery in Patients Treated with Bretschneider Cardioplegia.

Background Heart surgery with extracorporeal circulation (ECC) often leads to postoperative delirium (POD). This is associated with increased morbidity resulting in longer hospital stay and associated costs. The purpose of our study was to analyze the effect of intraoperative mannitol application on POD in patients undergoing elective aortic valve replacement (AVR). Materials and Method s In our retrospective single-center study, 259 patients underwent elective AVR, using Bretschneider cardioplegic solution for cardiac arrest, between 2014 and 2017. Patients were divided in mannitol ( n = 188) and nonmannitol ( n = 71) groups. POD was assessed using the confusion assessment method for the intensive care unit (ICU). Statistical significance was assumed at p < 0.05. Results Baseline patient characteristics did not differ between the groups. Incidence of POD was significantly higher in the nonmannitol group (33.8 vs. 13.8%; p = 0.001). These patients required longer ventilation time (24.1 vs. 17.1 hours; p = 0.021), higher reintubation rate (11.3 vs. 2.7%; p = 0.009), ICU readmission (12.7 vs. 4.8%; p = 0.026), prolonged ICU (112 vs. 70 hours; p = 0.040), and hospital stay (17.8 vs. 12.6 days; p < 0.001), leading to higher expenses (19,349 € vs. 16,606 €, p < 0.001). A 30-day mortality was not affected, but nonmannitol group showed higher Simplified Acute Physiology Score II score (32.2 vs. 28.7; p < 0.001). Mannitol substitution was independently associated with lower incidence of POD (odds ratio: 0.40; 95% confidence interval: 0.18–0.89; p = 0.02). Conclusion Treatment with mannitol during ECC was associated with decreased incidence of POD. This was accompanied by shorter ventilation time, ICU and hospital stay, and lower treatment expenses.

WARM VERSUS COLD INTERMITTENT BLOOD CARDIOPLEGIA FOR MYOCARDIAL PROTECTION DURING ON-PUMP CORONARY ARTERY BYPASS GRAFTING

Background: Obtaining an optimal surgical result depends on performing a technically proficient operation while protecting the heart from potential damage. Cardioplegia is an essential component in myocardial protection during aortic cross-clamping and cardiopulmonary bypass. The development of cardioplegia solutions is one of the major advances in cardiac surgery that allowed surgeons to extend the period of ischemic arrest to well over 3 hours to perform complex surgical procedures without adversely affecting myocardial functio).Aim of the work: We sought to compare between two specific modalities of myocardial protection using either intermittent ante-grade cold blood cardioplegia or warm blood cardioplegia.Patients and Methods: This prospective study included 200 successive adult patients who have undergone elective on-pump coronary artery bypass grafting (CABG) operations. Randomization was done immediately before the beginning of the operation so that group allocation was blinded to the patient. Participants were recruited between 14 January 2017 and 10 July 2019 at Mahalla Cardiac Center. All patients were thoroughly evaluated preoperatively, intraoperatively, and postoperatively.Results: There was no statistically significant difference between the two groups as regards bypass and cross clamp times. However, there was a statistically significant difference between the two groups as regards spontaneous defibrillation. There were no significant differences in both groups regarding the needed either inotropic support, or an IABP to achieve weaning. The total period of mechanical ventilation was statistically shorter in the warm group compared to the cold group.Conclusion: We found that there was no difference in the clinical effect of warm or cold blood cardioplegia despite the relative increase in postoperative serum cTnI in the warm cardioplegia group. Both strategies appear to allow a comparable and satisfactory method for myocardial protection during the period of cardiac arrest.

Cold non-ischemic heart preservation with continuous perfusion prevents early graft failure in orthotopic pig-to-baboon xenotransplantation.

Successful preclinical transplantations of porcine hearts into baboon recipients are required before commencing clinical trials. Despite years of research, over half of the orthotopic cardiac xenografts were lost during the first 48hours after transplantation, primarily caused by perioperative cardiac xenograft dysfunction (PCXD). To decrease the rate of PCXD, we adopted a preservation technique of cold non-ischemic perfusion for our ongoing pig-to-baboon cardiac xenotransplantation project. Fourteen orthotopic cardiac xenotransplantation experiments were carried out with genetically modified juvenile pigs (GGTA1- KO/hCD46/hTBM) as donors and captive-bred baboons as recipients. Organ preservation was compared according to the two techniques applied: cold static ischemic cardioplegia (IC; n=5) and cold non-ischemic continuous perfusion (CP; n=9) with an oxygenated albumin-containing hyperoncotic cardioplegic solution containing nutrients, erythrocytes and hormones. Prior to surgery, we measured serum levels of preformed anti-non-Gal-antibodies. During surgery, hemodynamic parameters were monitored with transpulmonary thermodilution. Central venous blood gas analyses were taken at regular intervals to estimate oxygen extraction, as well as lactate production. After surgery, we measured troponine T and serum parameters of the recipient's kidney, liver and coagulation functions. In porcine grafts preserved with IC, we found significantly depressed systolic cardiac function after transplantation which did not recover despite increasing inotropic support. Postoperative oxygen extraction and lactate production were significantly increased. Troponin T, creatinine, aspartate aminotransferase levels were pathologically high, whereas prothrombin ratios were abnormally low. In three of five IC experiments, PCXD developed within 24 hours. By contrast, all nine hearts preserved with CP retained fully preserved systolic function, none showed any signs of PCXD. Oxygen extraction was within normal ranges; serum lactate as well as parameters of organ functions were only mildly elevated. Preformed anti-non-Gal-antibodies were similar in recipients receiving grafts from either IC or CP preservation. While standard ischemic cardioplegia solutions have been used with great success in human allotransplantation over many years, our data indicate that they are insufficient for preservation of porcine hearts transplanted into baboons: Ischemic storage caused severe impairment of cardiac function and decreased tissue oxygen supply, leading to multi-organ failure in more than half of the xenotransplantation experiments. In contrast, cold non-ischemic heart preservation with continuous perfusion reliably prevented early graft failure. Consistent survival in the perioperative phase is a prerequisite for preclinical long-term results after cardiac xenotransplantation.

WITHDRAWN: Cardioplegia and Cardiac surgery: A comprehensive literature review

Abstract Myocardial protection is an essential component of cardiac surgery. Cardioplegic solutions induce cardiac arrest in order to optimise operative conditions. Importantly, cardioplegia enhances myocardial recovery and improves clinical outcomes. There have been considerable advances in myocardial protection since the concept of chemical cardioplegia was first introduced in 1955. Methods can be characterised according to solution, temperature, additives and delivery methods. In spite of significant research, there is still no clear consensus on the cardioplegic method or solution associated with optimum clinical outcomes. This is a comprehensive and comparative overview of the available and upcoming methods in the field of myocardial protection.

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.

Echocardiographic assessment in aortic valve insufficiency for cardioplegic solution administration.

Echocardiographic assessment in aortic valve insufficiency for cardioplegic solution administration.

Use of del Nido cardioplegia in acute aortic dissection surgery.

Del Nido cardioplegia solution provides a depolarized hyperkalemic arrest lasting up to 60 minutes. Single-dose del Nido cardioplegia solution may offer an alternative myocardial protection strategy to conventional whole blood cardioplegia following acute aortic dissection surgery. We retrospectively reviewed 122 consecutive patients with acute aortic dissection undergoing arch reconstruction surgery procedure with cardioplegia arrest from January 2017 to December 2019. Patients exclusively received with whole blood cardioplegia (n = 60, January 2017-December 2018) or del Nido cardioplegia (n = 62, January 2018-December 2019). Preoperative and postoperative data were retrospectively reviewed. No significant difference between two groups in mortality (4/60 vs 3/62, p = 0.964), cardiopulmonary bypass time (168.0 ± 10.5 minute vs 165.0 ± 12.5 minute, p = 0.154), aortic cross-clamp time (91.8 ± 9.0 minute vs 93.2 ± 9.5 minute, p = 0.405), selective antegrade cerebral perfusion time (21.8 ± 5.0 minute vs 22.4 ± 4.7 minute, p = 0.496) and postoperative vasoactive inotropic score (34.8 ± 1.9 vs 35.2 ± 2.1, p = 0.272), neurological complications rate (8/60 vs 12/62, p = 0.523), renal insufficiency rate (5/60 vs 7/62, p = 0.807) and the troponin T level (304.8 ± 111.3 vs 315.0 ± 94.9, p = 0.588), respectively. Mean volume of crystalloid was significantly higher in the del Nido group compared to the whole blood cardioplegia group (1010.2 ± 20.3 mL vs 300.0 ± 19.6 mL, p < 0.001). Patients requiring defibrillation was 7/62 vs 28/60 (p < 0.001), with statistical difference in both groups. Short-term outcomes in acute aortic dissection surgery using del Nido cardioplegia solution were acceptable and comparable to conventional multi-dose whole blood cardioplegia. Del Nido cardioplegia technique is associated with lower defibrillations rate and requires a reduced frequency of infusions that results in longer durations between infusions and may be a feasible alternative to conventional whole blood cardioplegia solution in acute aortic dissection surgery.

Del Nido Cardioplegia Versus Cold Blood Cardioplegia in Adult Cardiac Surgery: Protocol for a Randomized Controlled Trial.

BackgroundThe use of cardioplegia solutions as a myocardial protection technique is essential during cardiac surgery with cardiopulmonary bypass. The del Nido cardioplegia solution (DNS) has been widely used as a myocardial preservation technique for pediatric patients undergoing cardiac surgery with cardiopulmonary bypass. Its unique pharmacological features have created growing interest for adult cardiac surgery, especially for elderly patients or those with ventricular dysfunction who are more prone to ischemia-reperfusion injury. Ever since its implementation, several retrospective studies have been published to validate the efficacy, safety, and efficiency of DNS in adult patients undergoing coronary revascularization, valve replacement, or combined procedures. Recently, a meta-analysis based on nine retrospective studies was published claiming the noninferiority of DNS compared to other conventional cardioplegia solutions. Few prospective randomized studies have been conducted whose primary outcome was the assessment of DNS clinical efficacy compared to other solutions commonly used in adult patients.ObjectiveThe aim of this randomized clinical trial is to assess the benefits of DNS compared to Cardi-Braun blood cardioplegia solution in clinical and biochemical terms regarding myocardial protection during adult cardiac surgery.MethodsThis is the protocol of a controlled, randomized, single-center clinical trial carried out at the Puerta de Hierro Majadahonda University Hospital in Spain. A total of 474 participants over the age of 18 years undergoing elective cardiac surgery with cardiopulmonary bypass will be assigned to groups by simple randomization to receive either DNS or Cardi-Braun blood cardioplegia solution. The primary outcome will be the differences between groups in myocardial protection in biochemical terms (ie, perioperative troponin levels) and clinical terms (ie, presence of the composite variable acute cardiovascular event). The clinical trial will be carried out under conditions of respect for the fundamental rights of the person and the ethical principles that affect biomedical research with human beings, as well as in accordance with international recommendations contained in the Declaration of Helsinki and its subsequent revisions.ResultsThe inclusion process started in 2018. Data cleaning and analyses are expected to take place in the fall of 2020 and the results are expected in January 2021.ConclusionsThis study is particularly relevant as it will be one of the first to analyze the clinical effects of del Nido cardioplegia on the basis of direct myocardial protection parameters. In light of published studies, carrying out prospective studies based on primary clinical objectives with a larger sample, high-risk patients, and longer cardiopulmonary bypass times continues to be necessary. We believe that our study addresses an important gap in the knowledge of del Nido cardioplegia in adult patient cardiac surgery and will be able to clarify the possible benefits of this method in a large population of patients undergoing these procedures.Trial RegistrationEuropean Union Drug Regulating Authorities Clinical Trials Database (EudraCT) 2017-005144-14; https://www.clinicaltrialsregister.eu/ctr-search/search?query=2017-005144-14+; ClinicalTrials.gov NCT04094168; https://clinicaltrials.gov/ct2/show/NCT04094168International Registered Report Identifier (IRRID)DERR1-10.2196/17826

Effectiveness of Bokeria—Boldyrev ACH Solution in Surgerical Treatment of Adult Patients with Obstructive Hypertrophic Cardiomyopathy

The study examined effectiveness of pharmaco-cold cardioplegia employing solutions of enhanced buffer capacity during surgery of obstructive hypertrophic cardiomyopathy in adult patients (N=51) operated during 2013-2018. In group 1 (N=28), the cardioplegia was performed with HTK (Custodiol) solution, whereas in group 2 (N=23), it was carried out with Bokeria-Boldyrev ACH solution. The mean, minimum, and maximum ages in group 1 were 46, 21, and 64 years, respectively; in group 2 - 42, 14, and 70 years, respectively. In both groups, the patients were subjected to myoectomy of exit pathway in the left ventricle according to Bokeria-Morrow operation and annuloplasty of tricuspid valve accompanied by reconstructive surgery (or replacement) of mitral valve. Atrial fibrillation (if any) was suppressed with cryoablation (-60°С) of the openings of the right and left pulmonary veins. The surgery was carried out in hypothermic mode at 28°C. The significant intergroup differences were observed in the asystole latent period after the onset of antegrade or retrograde injection of cardioplegic solution. In group 1, the asystole latent periods determined after antegrade or retrograde injection were 53±7 or 170±30 sec, respectively; in group 2 - 32±6 and 97±11 sec (p<0.0001), respectively. The mean times of aortic cross-clumping in groups 1 and 2 were 66±8 and 64±6 min, respectively; the electromechanical action of the heart restored after aortic unclamping in 35±7 and 30±6 sec, respectively. The biochemical and clinical data revealed no significant intergroup differences. Overall, novel Bokeria-Boldyrev ACH cardioplegic solution secured effective protection of the myocardium against intraoperative ischemia in adult patients with obstructive hypertrophic cardiomyopathy and significantly decreased the asystole latent period.

Operative consideration in patient with cryoglobulinaemia undergoing cardiac surgery with use of cardiopulmonary bypass

Abstract Cryoglobulinaemia can be defined as the presence of single or mixed immunoglobulins in the serum, which precipitate at sub-homeostatic temperatures and redissolve at higher temperatures. This condition in the context of cardiac surgery can precipitate systemic complications secondary to cold agglutination and lead to significant perioperative problems with the cardiopulmonary bypass machine and the extracorporeal circuit. We present a case of a 74-year-old gentleman with cryoglobulinaemia who underwent mitral valve repair and coronary artery bypass graft surgery. The patient was to undergo preoperative plasmapheresis to reduce circulating levels of cryoglobulin and thereby decrease the risk of potential protein agglutination during cardiopulmonary bypass. Operative considerations included the level of systemic temperature required, the temperature of the cardioplegia solution, level of anticoagulation and the speed and timing of rewarming of the patient to normal homeostatic temperatures. The postoperative management also consisted of early plasmapheresis to further reduce the number of cryoglobulins.

Warm blood cardioplegia versus cold crystalloid cardioplegia for coronary artery bypass grafting (CABG) in patients with low ejection fraction

BackgroundPatients with reduced ejection fraction (EF) undergoing CABG are more likely to develop postoperative morbidity and mortality. It is controversial about which cardioplegia solution, temperature, and method of administration ensure optimal cardiac muscle preservation during CABG surgery.Aim of the studyThe aim of the study was to compare intermittent antegrade warm blood cardioplegia with cold crystalloid cardioplegia during CABG in patients with low EF (30–40%).MethodsPatients (n = 100) undergoing elective isolated on-pump CABG were prospectively randomized into group I (n = 50) which received antegrade cold crystalloid cardioplegia and group II (n = 50) which received antegrade warm blood cardioplegia. Blood samples were collected immediately and 12 and 24 h postoperatively. CK-MB and cardiac troponin I were measured and compared between the two groups. Other indicators such as use of inotropic support and use of intra-aortic balloon counter pulsation (IABC) were also documented.ResultsPreoperative demographic and clinical variables were matched in both groups. However, postoperative CK-MB and troponin I were higher in group I compared to group II. There was less need for inotropic support and IABC with better postoperative course in group II than in group I.ConclusionThere was a significant reduction in the release of cardiac enzymes and less need for inotropic support with better postoperative outcome in patients who received antegrade warm blood cardioplegia versus cold crystalloid cardioplegia.

Lidocaine adsorption to ethylene-vinyl acetate infusion bags decreases its availability in del Nido cardioplegia solution

Del Nido cardioplegia solution (dNCS) is frequently used in cardiac surgery. As dNCS is often in-house prepared by hospital pharmacies, an appropriate preparation and storage conditions need to be found and validated. In this study, an 8-week (i.e., 56 days) stability test was performed to monitor the effect of several variables on the stability of dNCS manufactured internally at a hospital pharmacy. Six dNCS variants were prepared that differed in the material of container used, i.e., ethylene-vinyl acetate (EVA) infusion bags or glass infusion bottles, magnesium ions source, and the presence or absence of sodium bicarbonate. Each variant was evaluated for its stability while maintaining at 4 °C, 22 °C, or 50 °C. The concentrations of constituents were monitored using HPLC and capillary electrophoresis. It was found that dNCS is stable at 4 °C for 8 weeks and that the replacement of magnesium chloride with magnesium sulfate and/or the absence of sodium bicarbonate has no effect on the stability. On the other hand, if dNCS is not refrigerated or maintained at elevated temperature, the lidocaine concentration in the solution stored in EVA bags can be significantly altered by adsorption of lidocaine to infusion bag material (within 25 days, lidocaine concentration decreases as low as to one half of the original value). Therefore, the dNCS stored in EVA bags should be maintained at 4 °C to avoid alternation of its pharmacological effect, because when the solution stored in EVA bag is maintained at elevated temperature, the concentration of lidocaine can be significantly changed. Such change influences the pharmacological effect of the solution leads to serious complications and even endangers the health or life of patients.

Isolation of Human Ventricular Cardiomyocytes from Vibratome-Cut Myocardial Slices.

The isolation of ventricular cardiac myocytes from animal and human hearts is a fundamental method in cardiac research. Animal cardiomyocytes are commonly isolated by coronary perfusion with digestive enzymes. However, isolating human cardiomyocytes is challenging because human myocardial specimens usually do not allow for coronary perfusion, and alternative isolation protocols result in poor yields of viable cells. In addition, human myocardial specimens are rare and only regularly available at institutions with on-site cardiac surgery. This hampers the translation of findings from animal to human cardiomyocytes. Described here is a reliable protocol that enables efficient isolation of ventricular myocytes from human and animal myocardium. To increase the surface-to-volume ratio while minimizing cell damage, myocardial tissue slices 300 µm thick are generated from myocardial specimens with a vibratome. Tissue slices are then digested with protease and collagenase. Rat myocardium was used to establish the protocol and quantify yields of viable, calcium-tolerant myocytes by flow-cytometric cell counting. Comparison with the commonly used tissue-chunk method showed significantly higher yields of rod-shaped cardiomyocytes (41.5 ± 11.9 vs. 7.89 ± 3.6%, p < 0.05). The protocol was translated to failing and non-failing human myocardium, where yields were similar as in rat myocardium and, again, markedly higher than with the tissue-chunk method (45.0 ± 15.0 vs. 6.87 ± 5.23 cells/mg, p < 0.05). Notably, with the protocol presented it is possible to isolate reasonable numbers of viable human cardiomyocytes (9-200 cells/mg) from minimal amounts of tissue (<50 mg). Thus, the method is applicable to healthy and failing myocardium from both human and animal hearts. Furthermore, it is possible to isolate excitable and contractile myocytes from human tissue specimens stored for up to 36 h in cold cardioplegic solution, rendering the method particularly useful for laboratories at institutions without on-site cardiac surgery.

Comparative study between the use of St. Thomas' II cardioplegia and del Nido cardioplegia in patients who underwent open-heart surgery

Background and Aims: Cardioplegia is used to arrest the heart after the application of an aortic cross-clamp that interrupts the coronary circulation. Commonly used St. Thomas’II cardioplegic solution has to be repeated at short intervals, which may cause additional myocardial injury. So, this study is done to determine whether del Nido (DN) cardioplegia, which has a longer duration of arrest with a single dose, provides equivalent or better myocardial protection as compared to St. Thomas’ II Cardioplegia.&#x0D; Methods: A prospective observational study was done among 100 patients who underwent open-heart surgery with myocardial protection, between September 2016 to August 2018 in Bangabandhu Sheikh Mujib Medical University, Bangladesh. Patients were divided into two groups, group A (n=50) for del Nido cardioplegic and group B (n=50) for St. Thomas’ II cardioplegia. We compared the amount of cardioplegic solution, Aortic cross-clamp time, cardiopulmonary bypass (CPB) time, ischemic time, arrhythmia, spontaneous sinus rhythm after declamping, intraoperative DC shock requirement, postoperative left ventricular ejection fraction, serum potassium level, low cardiac output, cardiac Troponin level I and CK-MB release after 12 hours and 24 hours, presence of myocardial infarction and death.&#x0D; Results: The per-operative variable suggested spontaneous activity during a cardiac arrest was 2% in del Nido and 14% in St. Thomas’ II group (p=0.044). Similarly, during intraoperative phase spontaneous restoration of cardiac activity after the procedure in del Nido was 2.90 ± 1.16 minutes and in St. Thomas’ II was 1.8 ± 0.615 minutes (p=0.001). However total bypass time and ischemic time were not significant. During the postoperative period, Troponin I and CKMB were measured at 12 hours and 24 hours which were not statistically different in two groups. Postoperatively, low output syndrome was seen among 3 patients in del Nido Group and 4 patients in St. Thomas’ II group (p-value=0.341).&#x0D; Conclusion: This study showed with the use of del Nido cardioplegia provides equivalent myocardial protection to St. Thomas’ II cardioplegia, with the use of only single-dose cardioplegia.

The Comparison of the Effect of Handmade Del Nido and St. Thomas Cardioplegia Solutions on Quantitative Levels of Troponin I and Creatine Kinase-Myocardial Band (CPK-MB) in Repair of Pediatric Ventricular Septal Defect

The Comparison of the Effect of Handmade Del Nido and St. Thomas Cardioplegia Solutions on Quantitative Levels of Troponin I and Creatine Kinase-Myocardial Band (CPK-MB) in Repair of Pediatric Ventricular Septal Defect

MicroRNA Expression Profile Changes after Cardiopulmonary Bypass and Ischemia/Reperfusion-Injury in a Porcine Model of Cardioplegic Arrest.

Identification of microRNAs (miRNA) associated with cardiopulmonary bypass, cardiac arrest and subsequent myocardial ischemia/reperfusion may unravel novel therapeutic targets and biomarkers. The primary aim of the present study was to investigate the effects of cardiopulmonary bypass and temperature of cardioplegic arrest on myocardial miRNA profile in pigs’ left ventricular tissue. We employed next-generation sequencing to analyse miRNA profiles in the following groups: (1) hearts were arrested with antegrade warm St Thomas Hospital No. 2 (STH2) cardioplegia (n = 5; STH2-warm, 37 °C) and (2) cold STH2 (n = 6; STH2-cold, 4 °C) cardioplegia. Sixty min of ischemia was followed by 60 min of on-pump reperfusion with an additional 90 min of off-pump reperfusion. In addition, two groups without cardiac arrest (off-pump and on-pump group; n = 3, respectively) served as additional controls. STH2-warm and STH2-cold cardioplegia revealed no hemodynamic differences. In contrast, coronary venous creatine kinase-myocardial band (CK-MB) levels were significantly lower in pigs receiving STH2-warm cardioplegia (p < 0.05). Principal component analysis revealed that cardiopulmonary bypass and cardioplegic arrest markedly affected miRNAs in left ventricular tissue. Accordingly, ssc-miR-122, ssc-miR-10a-5p, ssc-miR-193a-3p, ssc-miR-499-3p, ssc-miR-374a-5p, ssc-miR-345-5p, ssc-miR-142-3p, ssc-miR-424-5p, ssc-miR-545-3p, ssc-miR-30b-5p, ssc-miR-145-5p, ssc-miR-374b-5p and ssc-miR-139-3p were differently regulated by cardiopulmonary bypass (false discovery rate (FDR) < 0.05 versus off-pump group). However, only ssc-miR-451 was differently expressed between STH2-warm and STH2-cold (FDR < 0.05). These data demonstrate for the first time that cardiopulmonary bypass and temperature of cardioplegic solution affected the expression of miRNAs in left ventricular tissue. In conclusion, specific miRNAs are potential therapeutic targets for limiting ischemia-reperfusion injury in patients undergoing cardiac surgery.

DOES CARDIOPLEGIA PROVIDE CARDIAC PROTECTION BY INDUCING Nr‐E2 RELATED FACTOR‐2(Nrf2)

BackgroundOpen heart surgery is often an unavoidable procedure for treatment of cardiovascular disease. Myocardial ischemia‐reperfusion injury (MIRI) can occur as a result of cardiopulmonary bypass. The multifaceted mechanisms of MIRI involve the generation of proinflammatory mediators and increases in reactive oxygen species (ROS), resulting in damage to proteins, lipids, and DNA, ultimately impacting postoperative cardiac function and outcomes. Nf‐E2 related factor‐2 (Nrf2), a basic leucine zipper transcription factor, is regarded as one of the most important regulators in antioxidant pathways. Nrf2 binds to and activates the Antioxidant Response Element (ARE) in the promoters of many antioxidant and detoxification genes.PurposeWe addressed whether or not cardioplegic solutions induce the activation of Nrf2, therefore serving to protect the myocardium from MIRI. Methods. We used adult cardiomyocytes in culture to test whether or not four different types of cardioplegic solutions induce Nrf2. The conditions tested include routine laboratory cell culture at 37°C and hypothermic temperatures of 10–20°C.ResultsOur data show that certain cardioplegic solutions caused increases in Nrf2 protein levels under both cell culture and hypothermic conditions. ARE luciferase reporter assay confirmed Nrf2 activation by the cardioplegic solutions. Both High K and Del Nido showed reliable activation of Nrf2.ConclusionsOur data supports our hypothesis that cardioplegic solutions can be cardiac protective via the activation of Nrf2.Support or Funding InformationThis work is supported by research grants of NIH R01 GM125212 (QMC), NIH R01 GM126165 (QMC), Holsclaw Endowment (QMC)

Differential Receptor‐Mediated Inducible Gene Expression in Post Infarction Cardiac Fibroblasts is Altered by Intrinsic Exercise Phenotype

BackgroundIschemic heart disease is a major cause of morbidity. Regular active exercise is therapeutic after myocardial infarction, but up to 70% of individual exercise capacity is due to an intrinsic genetic component. Intrinsic capacity can be studied using high (HCR) and low (LCR) aerobic running capacity rat strains. The phenotypes differ by more than 5 fold in sedentary average running distance and time. The HCR rats have been characterized as “disease resistant”, while the LCRs are characterized as “disease prone”. In the heart, cardiac fibroblasts play a critical role in healing post myocardial infarction, but little is known about the effect of intrinsic aerobic capacity on the inducible, receptor‐mediated fibroblast gene expression pathways following ischemia reperfusion.MethodsOn each study day, one HCR/LCR pair (n = 8 each) was anesthetized and hearts were rapidly excised. The hearts were immediately flushed with iced hyperkalemic, hyperosmotic, cardioplegia solution, and subjected to cold global ischemic arrest (80 min). Following arrest, the hearts underwent warm reperfusion (120 min) using a Langendorff style perfusion system. Following reperfusion, the heart was weighed and the LV was isolated. A mid ventricular ring was obtained to estimate infarction size (TTC), and part of the remaining tissue (~150 mg) was transferred to homogenation buffer on ice for subsequent isolation of fibroblasts. Cardiac fibroblasts from the LV of HCRs and LCR rats were isolated, and cultured in 6 well plates. Different wells were treated with BMP7, Angiotensin or both, with or without receptor antagonists (BMP2R, noggin; AngR, Losartan). After conditioning, RNA was isolated from the cultured fibroblasts, and RT‐PCR was used to determine baseline gene expression for Collagen I and III, MMP2, TIMP1, BMPR2, ATR1, SMAD5, and Bag3 in each phenotype.ResultsOverall, Collagen I gene expression was significantly higher in LCRs more than HCRs, but the activating pathways were phenotype dependent. Treating with Ang II induced gene expression for collagen I in LCR fibroblasts but not HCR, and was completely blocked with Losartan. By Contrast, treating with BMP7 induced gene expression of collagen I in HCR fibroblasts but not LCRs, and was completely blocked by noggin. Treating the fibroblasts with a combination of receptor agonists confirmed the phenotypic selectivity of the inducible pathways. Inhibiting BMP7 using noggin brought collagen I gene expression back to the control level with no changes in LCRs.ConclusionThe Angiotensin receptor pathway is responsive only in post‐ischemic LCR cardiac fibroblasts, and the BMP receptor pathway is responsive only in post‐ischemic HCR cardiac fibroblasts. How the intrinsic aerobic phenotype governs these pathways is unknown, but could shed new light on individuals who develop post‐infraction fibrosis despite therapeutic dosing with Angiotensin pathway antagonists.

Relative Profibrotic Gene Expression in Cardiac Fibroblasts from Low Aerobic Capacity “Disease Prone” Rats Following Ischemic Reperfusion

BackgroundIschemic heart disease is a major cause of morbidity. Regular active exercise is therapeutic after myocardial infarction, but up to 70% of individual exercise capacity is due to an intrinsic genetic component. Intrinsic capacity can be studied using high (HCR) and low (LCR) aerobic running capacity rat strains. The phenotypes differ by more than 5 fold in sedentary average running distance and time. The HCR rats have been characterized as “disease resistant”, while the LCRs are characterized as “disease prone”. In the heart, cardiac fibroblasts play a critical role in healing post myocardial infarction, but little is known about the effect of intrinsic aerobic capacity on early fibroblast gene expression following ischemia reperfusion.MethodsOn each study day, one HCR/LCR pair (n = 8 each) was anesthetized and hearts were rapidly excised. The hearts were immediately flushed with iced hyperkalemic, hyperosmotic, cardioplegia solution, and subjected to cold global ischemic arrest (80 min). Following arrest, the hearts underwent warm reperfusion (120 min) using a Langendorff style perfusion system. Following reperfusion, the heart was weighed and the LV was isolated. A mid ventricular ring was obtained to estimate infarction size (TTC), and part of the remaining tissue (~150 mg) was transferred to homogenation buffer on ice for subsequent isolation of fibroblasts. Cardiac fibroblasts from the LV of HCRs and LCR rats were isolated, cultured and characterized. Immunohistochemistry verified fibroblasts/myofibroblasts markers. RNA was isolated from the cultured fibroblasts, and RT‐PCR was used to determine baseline gene expression for Collagen I and III, MMP2, TIMP1, BMPR2, ATR1, SMAD5, and Bag3 in each phenotype.ResultsImmunocytochemistry successfully confirmed the presence of both fibroblasts and myofibroblasts markers. In these post IR fibroblast/myofibroblasts, LCRs showed significantly higher gene expression (49%) in the collagen I/collagen III ratio but lower expression of extracellular matrix regulatory genes including MMP2 (20%), TIMP1 (17%), and SMAD5 (15%) compared to HCRs counterparts. BMPR2 (50%), Agtr1a (25%), also were both decreased, and the anti‐apoptotic gene, Bag3, was significantly (67%) higher in LCRs.ConclusionThese results indicate that the LCR phenotype is predisposed to expressing a more fibrotic character in fibroblasts harvested immediately following IR, and may indicate poorer long term outcome/earlier onset heart failure following acute ischemic injury to the heart. While the phenotype produced no differences in the acute injury, there may be phenotypic differences that develop later during resolution of the injury.

Augmented Cardiac Mitochondrial Capacity in High Aerobic Capacity “Disease Resistant” Phenotype at Rest is Lost Following Ischemia Reperfusion

RationaleIschemic heart disease is a major cause of morbidity. Regular active exercise is therapeutic, but up to 70% of individual exercise capacity is due to an intrinsic genetic component. Intrinsic capacity can be studied using high (HCR) and low (LCR) aerobic running capacity rat strains. The phenotypes differ by more than 5 fold in sedentary average running distance and time. The HCR rats have been characterized as “disease resistant”, while the LCRs are characterized as “disease prone”. A consistent characteristic of the LCR is reduced metabolic capacity in several tissues, but metabolic capacity in cardiac tissue is not well studied in these phenotypes, particularly following the metabolic stress of ischemia and reperfusion.Methods32 HCR and LCR rats were obtained from the parent colony at the University of Toledo, housed under sedentary conditions, and fed normal chow. LCR and HCR animals were randomly assigned to either control (C, n = 8 each) or ischemia reperfusion (IR, n = 8 each). On each study day, one HCR/LCR pair was anesthetized and hearts were rapidly excised. In IR animals, the hearts were immediately flushed with iced hyperkalemic, hyperosmotic, cardioplegia solution, and subjected to cold global ischemic arrest (80 min). Following arrest, the hearts underwent warm reperfusion (120 min) using a Langendorff style perfusion system. Following reperfusion, the heart was weighed and the LV was isolated. A mid ventricular ring was obtained to estimate infarction size (TTC), and part of the remaining tissue (~150 mg) was transferred to homogenation buffer on ice. Isolated mitochondria (MITO) samples were prepared and used to determine respiratory capacity under different metabolic conditions (OROBOROS). MITO from control animals were obtained and prepared in similar fashion, but immediately following anesthesia and heart removal, and without IR. Citrate synthase activity was measured in each sample.ResultsIn the control rats, HCR MITO showed respiratory rates 32% higher at rest and more than 40% higher under maximally stimulated conditions, compared to LCR MITO (both p &lt; 0.05). After IR, resting MITO respiratory rates were decreased to about 10% in both strains, and the augmented capacity in HCRs was absent. Maximally stimulated rates also were decreased more than 50% from control, and were no longer different between phenotypes. Infarct size was not significantly different between HCR and LCR (49.2% ± 5.6 vs. 53.7% ± 4.9), nor was average coronary flow during reperfusion.ConclusionCardiac mitochondria from HCR were significantly higher in control conditions with each substrate tested. After IR insult, the cardiac mitochondrial respiratory rates were similar between phenotypes, as was infract size. Relatively, the loss of respiratory capacity was actually greater in HCR than LCR. Together, these data could suggest limits in the extent to which the HCR phenotype might be “protective” against acute tissue stressors. The extent to which any of these deficits could be “rescued” by an active exercise component is unknown.