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

Del Nido versus conventional blood cardioplegia in tetralogy of fallot repair: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

Compare outcomes of Del Nido (DN) versus conventional blood cardioplegia (BC) in the surgical repair of Tetralogy of Fallot (ToF).

METHODS

Medical databases were searched to identify relevant clinical trials. Meta-analysis was conducted for primary (cardiopulmonary bypass [CPB] and aortic cross-clamp [ACC] times, hospital and intensive care unit [ICU] length of stay [LOS], mechanical ventilation time) and secondary (adverse events, lactate levels, volume of additional cardioplegia) endpoints. Analysis was conducted for DN versus conventional blood cardioplegia, and we performed sensitivity analysis with leave one-out analysis for the primary outcome.

RESULTS

4 randomized controlled trials were included (n = 275). Mean differences (MD) with 95% confidence intervals (CI) were calculated with a random-effects model. Groups had similar CPB (MD -5.76 minutes; [-23.32 to 11.80]; p = 0.52) and ACC (MD 3.06 minutes; [-13.64 to 7.52]; p = 0.57) times, ICU (MD -6.42 hours; [-25.62 to 12.78]; p = 0.51) LOS and additional cardioplegia volume (MD -195.18 mL; [-434.19 to 43.82]; p = 0.11). The DN group had shorter hospital LOS (MD -0.81 days; [-1.25 to -0.36]; p = 0.0003) and time under mechanical ventilation (MD -4.57 hours; [-8.73 to -0.42]; p = 0.03). There was no difference in mortality.

CONCLUSIONS

DN cardioplegia has similar clinical outcomes and operative times compared to conventional blood cardioplegia in ToF surgery.

Comparison of Del Nido and histidine-tryptophan-ketoglutarate cardioplegia solutions: an animal study with prolonged ischaemia

Objective

Myocardial protection is important for a successful procedure cardiac surgery, and the key element of myocardial protection is cardioplegia. We compared Del Nido cardioplegia (DN) and Bretschneider histidine-tryptophan-ketoglutarate cardioplegia (HTK) regarding cardioprotective effects in a porcine model of prolonged ischaemia.

Methods

Landrace pigs weighing 50-60 kg were randomized to receive either DN (n = 9) or HTK (n = 9). All pigs underwent cardiac arrest for 90 min followed by 120 min of reperfusion/convalescence. A detailed set of laboratory, histological and functional parameters was acquired at baseline, during cardiac arrest and following reperfusion/convalescence.

Results

Pressure-volume measurements revealed better systolic and diastolic left ventricular performance in DN as compared to HTK (both p < 0.05). Haemoglobin decreased after application of the cardioplegic solution. The decrease was more pronounced in the HTK group than in the DN group (p < 0.01). In contrast to DN, sodium (p < 0.01) and chloride levels (p < 0.05) were significantly decreased in the HTK group after initiation of CPB and remained decreased after reperfusion. The number of animals requiring defibrillations to restore sinus rhythm significantly differed between the groups [HTK: 100% (n = 9/9) vs. DN: 44.4% (n = 4/9), p = 0.03]. Expression of ICAM-1 as a marker of endothelial dysfunction was lower in the DN group compared to the HTK group (p = 0.02). Histological evaluation, oxidative and nitrosative stress, mitochondrial membrane integrity and apoptosis markers were comparable between DN and HTK groups (all p > 0.05).

Conclusions

In this porcine model with prolonged ischaemia, DN was superior to HTK in terms of haemoglobin levels, blood electrolytes, spontaneous return of sinus rhythm, left ventricular function, and endothelial injury. Histomorphological parameters indicative of ischaemia/reperfusion injury, oxidative stress and mitochondrial function as well as apoptosis-inducing factors did not differ.

Pharmacological Cardioprotection against Ischemia Reperfusion Injury-The Search for a Clinical Effective Therapy

Pharmacological conditioning aims to protect the heart from myocardial ischemia-reperfusion injury (IRI). Despite extensive research in this area, today, a significant gap remains between experimental findings and clinical practice. This review provides an update on recent developments in pharmacological conditioning in the experimental setting and summarizes the clinical evidence of these cardioprotective strategies in the perioperative setting. We start describing the crucial cellular processes during ischemia and reperfusion that drive acute IRI through changes in critical compounds (∆G_ATP, Na⁺, Ca²⁺, pH, glycogen, succinate, glucose-6-phosphate, mitoHKII, acylcarnitines, BH₄, and NAD⁺). These compounds all precipitate common end-effector mechanisms of IRI, such as reactive oxygen species (ROS) generation, Ca²⁺ overload, and mitochondrial permeability transition pore opening (mPTP). We further discuss novel promising interventions targeting these processes, with emphasis on cardiomyocytes and the endothelium. The limited translatability from basic research to clinical practice is likely due to the lack of comorbidities, comedications, and peri-operative treatments in preclinical animal models, employing only monotherapy/monointervention, and the use of no-flow (always in preclinical models) versus low-flow ischemia (often in humans). Future research should focus on improved matching between preclinical models and clinical reality, and on aligning multitarget therapy with optimized dosing and timing towards the human condition.

Cardioplegia in Open Heart Surgery: Age Matters

INTRODUCTION

Cardioplegia is a pharmacological approach essential for the protection of the heart from ischemia-reperfusion (I-R) injury. Over the years, numerous cardioplegic solutions have been developed, with each cardioplegic approach having its advantages and disadvantages. Cardioplegic solutions can be divided into crystalloid and blood cardioplegic solutions, and an experienced surgeon chooses the type of solution based on the individual needs of patients in order to provide optimal heart protection. Importantly, the pediatric immature myocardium is structurally, physiologically, and metabolically different from the adult heart, and consequently its needs to achieve cardioplegic arrest strongly differ. Therefore, the present review aimed to provide a summary of the cardioplegic solutions available to pediatric patients with a special focus on emphasizing differences in heart injury after various cardioplegic solutions, the dosing strategies, and regimens.

MATERIAL AND METHODS

The PubMed database was searched using the terms cardioplegia, I-R, and pediatric population, and studies that investigated the influence of cardioplegic strategies on markers of cardiac muscle damage were further analyzed in this review.

CONCLUSIONS

A large body of evidence suggested more prominent benefits achieved with blood compared to those with crystalloid cardioplegia in pediatric myocardium preservation. However, standardized and uniform protocols have not been established so far, and an experienced surgeon chooses the type of cardioplegia solution based on the individual needs of patients, while the severity of myocardial damage strongly depends on the type and duration of the surgical procedure, overall patient condition, and presence of comorbidities, etc.

Hyperkalemic or Low Potassium Cardioplegia Protects against Reduction of Energy Metabolism by Oxidative Stress

Open-heart surgery is often an unavoidable option for the treatment of cardiovascular disease and prevention of cardiomyopathy. Cardiopulmonary bypass surgery requires manipulating cardiac contractile function via the perfusion of a cardioplegic solution. Procedure-associated ischemia and reperfusion (I/R) injury, a major source of oxidative stress, affects postoperative cardiac performance and long-term outcomes. Using large-scale liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics, we addressed whether cardioplegic solutions affect the baseline cellular metabolism and prevent metabolic reprogramming by oxidative stress. AC16 cardiomyocytes in culture were treated with commonly used cardioplegic solutions, High K+ (HK), Low K+ (LK), Del Nido (DN), histidine-tryptophan-ketoglutarate (HTK), or Celsior (CS). The overall metabolic profile shown by the principal component analysis (PCA) and heatmap revealed that HK or LK had a minimal impact on the baseline 78 metabolites, whereas HTK or CS significantly repressed the levels of multiple amino acids and sugars. H2O2-induced sublethal mild oxidative stress causes decreases in NAD, nicotinamide, or acetylcarnitine, but increases in glucose derivatives, including glucose 6-P, glucose 1-P, fructose, mannose, and mannose 6-P. Additional increases include metabolites of the pentose phosphate pathway, D-ribose-5-P, L-arabitol, adonitol, and xylitol. Pretreatment with HK or LK cardioplegic solution prevented most metabolic changes and increases of reactive oxygen species (ROS) elicited by H2O2. Our data indicate that HK and LK cardioplegic solutions preserve baseline metabolism and protect against metabolic reprogramming by oxidative stress.

Neuroprotective Effects of a Cardioplegic Combination (Adenosine, Lidocaine, and Magnesium) in an Ischemic Stroke Model

Adenosine, lidocaine, and magnesium (ALM) are clinically available cardioplegic solutions. We examined the effects of low-dose ALM on ischemic stroke in cell and animal models. Cobalt chloride (CoCl₂)-treated SH-SY5Y cells were used as a surrogate model to mimic oxygen-glucose deprivation conditions. The cells were incubated with different dilutions of ALM authentic solution (1.0 mM adenosine, 2.0 mM lidocaine, and5 mM MgSO4 in Earle's balanced salt solution). At a concentration of 2.5%, ALM significantly reduced CoCl₂-induced cell loss. This protective effect persisted even when ALM was administered 1 h after the insult. We used transient middle cerebral artery occlusion to investigate the therapeutic effects of ALM in vivo. Rats were randomly assigned to two groups-the experimental (ALM) and control (saline) groups-and infusion was administered during the ischemia for 1 h. The infarction area was significantly reduced in the ALM group compared with the control group (5.0% ± 2.0% vs. 23.5% ± 5.5%, p = 0.013). Neurological deficits were reduced in the ALM group compared with the control group (modified Longa score: 0 [0-1] vs. 2 [1-2], p = 0.047). This neuroprotective effect was substantiated by a reduction in the levels of various neuronal injury markers in plasma. These results demonstrate the neuroprotective effects of ALM and may provide a new therapeutic strategy for ischemic stroke.

Theoretical and Practical Aspects in the Use of Bretschneider Cardioplegia

The race for an ideal cardioplegic solution has remained enthusiastic since the beginning of the modern cardiac surgery era. The Bretschneider solution, belonging to the “intracellular cardioplegic” group, is safe and practical in myocardial protection during ischemic time. Over time, some particular concerns have arisen regarding the effects on cardiac metabolism and postoperative myocardial functioning. This paper reviews the most important standpoints in terms of theoretical and practical analyses.

The Role of Purinergic Signaling in Heart Transplantation

Heart transplantation remains the optimal treatment option for patients with end-stage heart disease. Growing evidence demonstrates that purinergic signals mediated by purine nucleotides and nucleosides play vital roles in heart transplantation, especially in the era of ischemia-reperfusion injury (IRI) and allograft rejection. Purinergic signaling consists of extracellular nucleotides and nucleosides, ecto-enzymes, and cell surface receptors; it participates in the regulation of many physiological and pathological processes. During transplantation, excess adenosine triphosphate (ATP) levels are released from damaged cells, and driver detrimental inflammatory responses largely via purinergic P2 receptors. Ecto-nucleosidases sequentially dephosphorylate extracellular ATP to ADP, AMP, and finally adenosine. Adenosine exerts a cardioprotective effect by its anti-inflammatory, antiplatelet, and vasodilation properties. This review focused on the role of purinergic signaling in IRI and rejection after heart transplantation, as well as the clinical applications and prospects of purinergic signaling.

Temperature-Related Effects of Myocardial Protection Strategies in Swine Hearts after Prolonged Warm Ischemia

Insufficient supply of cardiac grafts represents a severe obstacle in heart transplantation. Donation after circulatory death (DCD), in addition to conventional donation after brain death, is one promising option to overcome the organ shortage. However, DCD organs undergo an inevitably longer period of unprotected warm ischemia between circulatory arrest and graft procurement. In this scenario, we aim to improve heart preservation after a warm ischemic period of 20 min by testing different settings of myocardial protective strategies. Pig hearts were collected from a slaughterhouse and assigned to one of the five experimental groups: baseline (BL), cold cardioplegia (CC), cold cardioplegia + adenosine (CC-ADN), normothermic cardioplegia (NtC + CC) or normothermic cardioplegia + cold cardioplegia + adenosine (NtC-ADN + CC). After treatment, tissue biopsies were taken to assess mitochondrial morphology, antioxidant enzyme activity, lipid peroxidation and cytokine and chemokine expressions. NtC + CC treatment significantly prevented mitochondria swelling and mitochondrial cristae loss. Moreover, the antioxidant enzyme activity was lower in this group, as was lipid peroxidation, and the pro-inflammatory chemokine GM-CSF was diminished. Finally, we demonstrated that normothermic cardioplegia preserved mitochondria morphology, thus preventing oxidative stress and the subsequent inflammatory response. Therefore, normothermic cardioplegia is a better approach to preserve the heart after a warm ischemia period, with respect to cold cardioplegia, before transplantation.

St. Thomas Modified Cardioplegia Effects on Myoblasts’ Viability and Morphology

Background and Objectives: The cardioplegic arrest of the heart during cardiosurgical procedures is the crucial element of a cardioprotection strategy. Numerous clinical trials compare different cardioplegic solutions and cardioprotective protocols, but a relatively small number of papers apply to in vitro conditions using cultured cells. This work aimed to analyze whether it is possible to use the rat heart myocardium cells as an in vitro model to study the protective properties of St. Thomas cardioplegia (ST2C). Methods: The rat heart myocardium cells-H9C2 were incubated with cold cardioplegia for up to 24 h. After incubation, we determined: viability, confluency, and cell size, the thiol groups’ level by modifying Ellman’s method, Ki67, and Proliferating Cell Nuclear Antigen expression (PCNA). The impact on cells’ morphology was visualized by the ultrastructural (TEM) study and holotomograpic 3D imaging. Results: The viability and confluency analysis demonstrated that the safest exposure to ST2C, should not exceed 4h. An increased expression of Ki67 antigen and PCNA was observed. TEM and 3D imaging studies revealed vacuolization after the longest period of exposure (24). Conclusions: According to obtained results, we conclude that STC can play a protective role in cardiac surgery during heart arrest.