Randomized Clinical Trial of Hybrid vs. Surgical vs. Percutaneous Multivessel Coronary Revascularization: 5­year Follow-up of HREVS Trial.

Aim      To evaluate 5-year results of the HREVS (Hybrid REvascularization Versus Standarts) study.Material and methods  The study included 155 consecutive patients with multivessel coronary artery disease who were randomized into 3 groups: coronary artery bypass grafting (CABG) (n=50), hybrid coronary revascularization (HCR) (n=52) and percutaneous coronary intervention (PCI) (n=53) according to the consensus of the cardiology team on the technical and clinical feasibility of each of the three coronary revascularization strategies. The primary endpoint of the study was residual ischemia 12 months after revascularization according to data of single-photon emission computed tomography (SPECT). Secondary endpoints were major adverse cardiac and cerebrovascular events (MACCE) over 5 years of follow-up, which included all-cause death, myocardial infarction, stroke, and clinically determined repeat myocardial revascularization.Results Baseline characteristics of patients did not differ between study groups. Median residual ischemia determined by SPECT data after 12 months was not statistically significantly different in the CABG, HCR and PCI groups: 6.7 [4.6; 8.8]%, 6.4 [4.3; 8.5]% and 7.9 [5.9; 9.8]%, respectively (p=0.45). Mean follow-up period was 76.5 months (at least 60 months). There were no statistically significant differences in all-cause mortality between the CABG, HCR and PCI groups, 10.6, 12.8 and 8.2 %, respectively (p=0.23). Statistically significant differences between the groups of CABG, HCR and PCI in the incidence of myocardial infarction (12.8; 8.5 and 16.3 %; p=0.12), stroke (4.2; 6.4 and 10.2 % ; p=0.13), repeat revascularization for clinical indications (23.4; 23.4 and 34.7 %; p=0.11) were not observed either. However, the cumulative 5-year MACCE value was similar in the HCR group and the CABG group but significantly lower than in the PCI group (51.1, 51.1 and 69.4 %, respectively; p = 0.03).Conclusion      HCR that combines advantages of PCI and CABG is a promising strategy for coronary revascularization in multivessel coronary artery disease. HCR demonstrates satisfactory long-term results comparable to those of CABG but superior to PCI. To confirm the safety and efficacy of HCR, a large multicenter study is required that would have a sufficient power to evaluate clinical endpoints.

New Tissue-Engineered Vascular Matrix Based on Regenerated Silk Fibroin: in vitro Study.

The aim of the study was to make a vascular patch based on regenerated silk fibroin (SF) and study its physical and mechanical characteristics, biocompatibility and matrix properties in comparison with polyhydroxybutyrate/valerate/polycaprolactone with incorporated vascular endothelial growth factor (PHBV/PCL/VEGF) and commercial bovine xenopericardium (XP) flap in experiments in vitro. Materials and Methods: Tissue-engineered matrices were produced by electrospinning. The surface structure, physical and mechanical characteristics, hemocompatibility (erythrocyte hemolysis, aggregation, adhesion and activation of platelets after contact with the material) and matrix properties of vascular patches (adhesion, viability, metabolic activity of EA.hy926 cells on the material) were studied. Results: The surface of SF-based matrices and PHBV/PCL/VEGF-based tissue engineered patches had a porous and fibrous structure compared to a denser and more uniform XP flap. The physical and mechanical characteristics of SF matrices were close to those of native vessels. Along with this, tissue-engineered patches demonstrated high hemocompatible properties, which do not differ from those for commercial XP flap. Adhesion, viability, and metabolic activity of EA.hy926 endothelial cells also corresponded to the previously developed PHBV/PCL/VEGF matrix and XP flap, which indicates the nontoxicity and biocompatibility of SF matrices. Conclusion: Matrices produced from regenerated SF demonstrated satisfactory results, comparable to those for PHBV/PCL/VEGF and commercial XP flap, and in the case of platelet adhesion and activation, they outperformed these patches. In total, SF can be defined as material having sufficient biological compatibility, which makes it possible to consider a tissue-engineered matrix made from it as promising for implantation into the vascular wall.

Intracellular Kinase Mechanism of the Cytoprotective Action of Adaptation to Chronic Hypoxia in Anoxia/Reoxygenation of Cardiomyocytes.

On the model of anoxia/reoxygenation of isolated cardiomyocytes, we studied the role of kinases in the implementation of the cytoprotective effect of chronic continuous normobaric hypoxia (21 days on continuous exposure of rats at 12% O2). Anoxia/reoxygenation of cardiomyocytes from intact rats caused death of 16.5% cells, which was accompanied by the release of lactate dehydrogenase; in suspension of cardiomyocytes from adapted rats, only 6.8% cells died and the release of lactate dehydrogenase was lower by 60%. Incubation of cells with inhibitors of protein kinase C (chelerythrin, 10 mM), protein kinase Cδ (rottlerin, 1 µM), tyrosine kinases (genistein, 50 µM), but not with PI3K inhibitor (wortmannin, 100 nM) eliminated the cytoprotective effect of chronic continuous normobaric hypoxia. Thus, the cytoprotective effect of chronic normobaric hypoxia is realized through activation of protein kinase Cδ and tyrosine kinases, but not through PI3K.

Continuous Normobaric Hypoxia Improved Cardiac Bioenergetics after Ischemia/Reperfusion: Role of Opioid Receptors.

We analyzed the role of opioid receptors in the conditioning effect of continuous normobaric hypoxia on bioenergetics of the heart subjected to ischemia/reperfusion injury. Male Wistar rats were adapted to a 21-day continuous normobaric hypoxia (12% pO2). Then, the hearts were isolated and subjected to 45-min total ischemia followed by 30-min reperfusion. Damage to the myocardium was assessed by activity of creatine phosphokinase in the perfusate. Experiments on isolated mitochondria showed that ischemia/reperfusion injury decreased the respiration rate in state 3 (V3), the ratio of added ADP and oxygen consumption in respiration state 3 (ADP/O ratio), the mitochondrial potential across the inner membrane (Δψ), and Ca2+ binding capacity of mitochondria. In addition, ischemia/reperfusion injury decreased myocardial ATP. Preventive continuous normobaric hypoxia pronouncedly moderated these adverse effects of reperfusion. It was found that its protective effects were related to activation of cardiac µ- and δ2-opioid receptors.

The Role of Cardiac Opioid Receptors in the Cardioprotective Effect of Continuous Normobaric Hypoxia.

We studied the role of opioid receptor subtypes in improvement of the functional state of the heart during reperfusion after adaptation to continuous normobaric hypoxia. To this end, male Wistar rats were subjected to continuous normobaric hypoxia (12% O2). Then, the hearts were isolated and exposed to total 45-min ischemia followed by 30-min reperfusion. Opioid receptor antagonists were added to the perfusion solution prior to ischemia. It was found that continuous normobaric hypoxia reduced the release of creatine phosphokinase into the effluent, increased myocardial contractile force, and decreased the end-diastolic pressure during reperfusion; these positive effects were related to activation of cardiac δ2- and µ-opioid receptors.

[Clinical Manifestation of Stressful Cardiomyopathy (Takotsubo Syndrome) and the Problem of Differential Diagnosis with Acute Myocardial Infarction].

The presented data show that tacotsubo syndrome (TS) is characterized by the absence of coronary artery obstruction, cardiac contractile dysfunction, apical ballooning, and heart failure, and in some patients, ST-segment elevation and prolongation of the QTc interval. Every tenth patient with TS develops ventricular arrhythmias. Most of TS patients have elevated markers of necrosis (troponin I, troponin Т, and creatine kinase МВ (CK-МВ), which are considerably lower than in patients with acute myocardial infarction (AMI) with ST-segment elevation. The level of N-terminal pro-B-type natriuretic peptide (NT-proBNP), in contrast, is considerably higher in patients with TS than with AMI. Differential diagnosis of TS and AMI should be based on a multifaceted approach using coronary angiography, echocardiography, analysis of ECG, magnetic resonance imaging, single-photon emission computed tomography, and measurement of troponins, CK-MB, and NT-proBNP.

Effect of Chronic Continuous Normobaric Hypoxia on Functional State of Cardiac Mitochondria and Tolerance of Isolated Rat Heart to Ischemia and Reperfusion: Role of µ and delta2 Opioid Receptors.

Chronic continuous normobaric hypoxia (CNH) increases cardiac tolerance to ischemia/reperfusion injury in vivo and this effect is mediated via µ and delta2 opioid receptors (ORs) activation. CNH has also been shown to be cardioprotective in isolated rat heart. In this study, we hypothesize that this cardioprotective effect of CNH is mediated by activation of µ and delta2 ORs and preservation of mitochondrial function. Hearts from rats adapted to CNH (12 % oxygen) for 3 weeks were extracted, perfused in the Langendorff mode and subjected to 45 min of global ischemia and 30 min of reperfusion. Intervention groups were pretreated for 10 min with antagonists for different OR types: naloxone (300 nmol/l), the selective delta OR antagonist TIPP(psi) (30 nmol/l), the selective delta1 OR antagonist BNTX (1 nmol/l), the selective delta2 OR antagonist naltriben (1 nmol/l), the selective peptide µ OR antagonist CTAP (100 nmol/l) and the selective delta OR antagonist nor-binaltorphimine (3 nmol/l). Creatine kinase activity in coronary effluent and cardiac contractile function were monitored to assess cardiac injury and functional impairment. Additionally, cardiac tissue was collected to measure ATP and to isolate mitochondria to measure respiration rate and calcium retention capacity. Adaptation to CNH decreased myocardial creatine kinase release during reperfusion and improved the postischemic recovery of contractile function. Additionally, CNH improved mitochondrial state 3 and uncoupled respiration rates, ADP/O, mitochondrial transmembrane potential and calcium retention capacity and myocardial ATP level during reperfusion compared to the normoxic group. These protective effects were completely abolished by naloxone, TIPP(psi), naltriben, CTAP but not BNTX or nor-binaltorphimine. These results suggest that cardioprotection associated with adaptation to CNH is mediated by µ and delta2 opioid receptors activation and preservation of mitochondrial function.

Cardioprotective properties of opioid receptor agonists in rats with stress-induced cardiac injury.

The objectives of this study were to investigate the role of endogenous opioids in the mediation of stress-induced cardiomyopathy (SIC), and to evaluate which opioid receptors regulate heart resistance to immobilization stress. Wistar rats were subjected to 24 h immobilization stress. Stress-induced heart injury was assessed by 99mTc-pyrophosphate accumulation in the heart. The opioid receptor (OR) antagonists (naltrexone, NxMB - naltrexone methyl bromide, MR 2266, ICI 174.864) and agonists (DALDA, DAMGO, DSLET, U-50,488) were administered intraperitoneally prior to immobilization and 12 h after the start of stress. In addition, the selective micro OR agonists PL017 and DAMGO were administered intracerebroventricularly prior to stress. Finally pretreatment with guanethidine was used. Naltrexone did not alter the cardiac 99mTc-PP accumulation in stressed rats. NxMB aggravated stress-induced cardiomyopathy (P=0.005) (SIC). The selective micro OR agonist DALDA, which does not cross the blood-brain barrier, completely prevented (P=0.006) SIC. The micro OR agonist DAMGO exhibited weaker effect than DALDA. The selective delta ligand (DSLET) and kappa OR ligand (U-50,488) did not alter stress-induced 99mTc-pyrophosphate accumulation in the heart. Intracerebroventricular administration of the micro OR agonists aggravated SIC. Pretreatment with guanethidine abolished this effect (P=0.01). Guanethidine alone exhibited cardioprotective properties. A stimulation of central micro OR promotes an appearance of SIC. In contrast, stimulation of peripheral micro OR contributes to an increase in cardiac tolerance to stress.

[Prospects of Application of Remote Preconditioning at Heart Revascularization].

Remote ischemic preconditioning of the heart exerts anti-necrotic, antiarrhythmic, inotropic effects that have been demonstrated in clinical trials in cardiac surgery both in adults and children. However, so far there is no consensus between cardiologists regarding the impact of remote preconditioning on the incidence of intraoperative myocardial infarctions and mortality in the postoperative period. Until now there is no unanimity concerning choice of remote preconditioning protocol and timing of its application before cardiac surgery.

[The Role of Reactive Oxygen Species in the Pathogenesis of Adipocyte Dysfunction in Metabolic Syndrome. Prospects of Pharmacological Correction].

It is established that oxidative stress induces insulin resistance of adipocytes, increases secretion leptin, IL-6, TNF-α by adipocytes. Adiponectin secretion by adipocytes is reduced after the action of reactive oxygen species. Metabolic syndrome contributes to oxidative stress in adipose tissue, on the one hand due to the activation of production of reactive oxygen species by adipocyte NADPH-oxidase, and on the other hand by reducing the antioxidant defense adipocytes. It is found that obesity itself can induce oxidative stress. Chronic stress, glucocorticoids, mineralocorticoids, angiotensin-II, TNF-α play an important role in the pathogenesis of oxidative stress of adipocytes. Metformin remains the cure for the treatment of insulin resistance. The positive results in the treatment of metabolic syndrome by losartan were obtained. Antioxidants and flavonoids exhibit a positive impact on the course of the experimental metabolic syndrome.

[INVOLVEMENT OF 5-OPIOID RECEPTORS IN THE INCREASED RESISTANCE OF HEART AND MITOCHONDRIA TO IMPACT OF ISCHEMIA-REPERFUSION AFTER ADAPTATION TO CHRONIC CONTINUOUS HYPOXIA].

It was investigated the involvement of cardiac Ϭ-opioid receptors (OR) in increasing the resistance of the heart and myocardial mitochondria to ischemia-reperfusion after adaptation rats to chronic continuous normobaric hypoxia (CCNH). Rats were subjected to CCNH for 21 days at 12 % O2. It was evoked global ischemia (45 minutes) and reperfusion (30 minutes) of the isolated perfused heart. Adaptation to CCNH promoted a reduction of creatine kinase release from necrotic cardiomyocytes during reperfusion and improved reperfusion recovery of heart contractility. Mitochondrial respiratory and state of MPT pore were more resistant to ischemia-reperfusion in adapting rats. Perfusion of isolated hearts with TIPP(0) (30 nM/l, a selective Ϭ-OR-antagonist) or naltriben (1 nM/l, a selective 52-OR-antagonist) completely eliminated the cardioprotective effect of CCNH. BNTX (1 nM/l, a selective Ϭ-OR-antagonist) had no effect on the cardioprotective effect of CCNH. This data suggest that cardiac 52-OR involved in the increased resistance of the heart and mitochondria to ischemia-reperfusion after adaptation rats to CCNH.

[INVOLVEMENT OF NO-SYNTHASE IN THE INFARCT REDUCING EFFECT OF CONTINUOUS CHRONIC NORMOBARTC HYPOXTA].

It was investigated the role of inducible and endothelial NO-synthase (NOS) in the infaret reducing effect of chronic continuous normobaric hypoxia (CCNH) on the model of coronary artery occlusion and reperfusion in rats. Rats were subjected to hypoxic exposure (12% O2 during 21 days). It has found that CCNH causes an increase in total levels of nitrate and nitrite in deproteinized blood serum in 1.5-fold and 2-fold in myocardium compared with intact animals. This effect is manifested in intact animals and in rats with a 20 minute coronary artery occlusion and reperfusi- on. Chronic continuous normobaric hvoxia exhibited infarct soaring effect. which does not manifest after pretreatment with NO-synthase inhibitor NAME (10 mg/kg intravenously), the selective inhibitor of inducible NOS S-methylisothiourea (3 mg/kg intraperitoneally), but remained after blocking neuronal NOS with 7-nitronidazol (50 mg/kg intravenously). The findings suggest that the inducible NO-synthase and nitric oxide play an important role in the implementation of the infaret limiting effect of chronic continuous normobaric hvnoxia.

Contribution of Opioid Receptors to the Cytoprotective Effect of the Adaptation to Chronic Hypoxia at Anoxia/Reoxygenation of Isolated Cardiomyocytes.

We examined the role of opioid receptors in the cardioprotective effect of chronic continuous normobaric hypoxia in the model of anoxia/reoxygenation of isolated cardiomyocytes. Adaptation to hypoxia was provided by placing the rats for 21 days in an atmosphere with low O2 content. In intact rats, anoxia/reoxygenation of cardiomyocytes caused death of 23% cells and increased lactate dehydrogenase release from cardiomyocytes. In adapted rats, anoxia/ reoxygenation of cardiomyocytes caused death of only 2.5% cells and the release of lactate dehydrogenase decreased by 25%. Preincubation of the cells with opioid receptor blocker naloxone (300 nM) for 25 min eliminated the adaptive decrease in cell survival and reduction in lactate dehydrogenase release. Hence, opioid receptors of the cardiomyocytes contribute to the cytoprotective effect of chronic normobaric hypoxia.

[Reactive oxygen species are triggers and mediators of an increase in cardiac tolerance to impact of ischemia-reperfusion].

Reactive oxygen species (ROS) are triggers of ischemic preconditioning (IP). On the role of intracellular messengers of such cardioprotective effect of preconditioning claim: O2*, H2O2, OH*. However, we cannot exclude the possibility that other reactive oxygen metabolites also involved in the IP. Presented data suggest that IP enhances the production of ROS. The source of ROS may be mitochondrial respiratory chain and NADPH oxidase. Exogenous reactive oxygen species (O2*, H2O2) mimic the cardioprotective effect of preconditioning. Preconditioning prevents free radical damage of the heart during ischemia-reperfusion. The protective effect of IP is the consequence of reducing the production of ROS or the result of increased formation of endogenous antioxidants. Antioxidant enzymes are not involved in the protective effect of IP. Cardioprotective effect of many compounds (bradykinin, opioids, acetylcholine, phenylephrine, tumor necrosis factor-α, volatile anesthetics, protonophores, diazoxide, angiotensin II) depends on the increased production of ROS.

Functional state of myocardial mitochondria in ischemia reperfusion of the heart in rats adapted to hypoxia.

Parameters of respiration, transmembrane potential, and Ca(2+)-binding capacity of mitochondria isolated from Langendorff-perfused hearts of rats adapted to normobaric hypoxia were analyzed. Ischemia and reperfusion modeling in intact and adapted animals reduced Ca(2+)-binding capacity of mitochondria, which indicated increased sensitivity of mitochondrial permeability transition pores (MPTP) to calcium ions. These changes were accompanied by a decrease in transmembrane potential, ADP/O coefficient (ratio of added ADP to oxygen consumption in State 3), and inhibition of State 3 respiration. At the same time, adaptation attenuated the negative effect of ischemia and reperfusion on the functional state of mitochondria.

[Trigger mechanism of adaptive phenomenon of ischemic heart postconditioning].

Analysis of published data indicates on trigger role of protons, adenosine, opioids, bradykinin, calcitonin gene-related peptide, nitric oxide, epoxyeicosatrienoic acid, reactive oxygen species, hydrogen sulfide in ischemic heart postconditioning. It is shown that B-type natriuretic peptide, transforming growth factor-beta1, cardiotrophin-1, urocortin, acetylcholine, insulin and carbon monoxide can mimic postconditioning phenomenon.