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Yi J, Duan H, Chen K, Wen C, Cao Y, Gao H. Cardiac Electrophysiological Changes and Downregulated Connexin 43 Prompts Reperfusion Arrhythmias Induced by Hypothermic Ischemia-Reperfusion Injury in Isolated Rat Hearts. J Cardiovasc Transl Res 2022; 15:1464-1473. [PMID: 35689125 DOI: 10.1007/s12265-022-10256-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 04/04/2022] [Indexed: 10/18/2022]
Abstract
The purpose of this study was to determine the utility of the monophasic action potential (MAP) changes as an arrhythmic biomarker in hypothermic ischemia-reperfusion. The hypothermic ischemia-reperfusion model was subjected to 60 min of cardioplegic arrest while the isolated rat hearts were preserved with a multidose cold K-H solution at 4 °C. During the reperfusion period, the heart's arrhythmia and monophasic action potential were also monitored. The myocardial damage was assessed using HE and TTC stains. Immunohistochemistry and Western blotting were used to assess the expression and distribution of Connexin 43 (Cx43) and Akt. Collectively, prolonged action potential durations, increased dispersion of repolarization, and downregulated and lateralized Cx43 all contribute to the derangement of electrical impulse propagation that may underlie arrhythmogenesis in the cold ischemic heart following cardioplegic arrest. MAP might be used as a biomarker for arrhythmias caused by hypothermic ischemia-reperfusion.
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Affiliation(s)
- Jing Yi
- Translational Medicine Research Center, Clinical Medical School, Guizhou Medical University, No. 9, Beijing Road, Guiyang, 550004, Guizhou, China
- Department of Anesthesiology, The Affiliated Hospital of Guizhou Medical University, No. 28, Guiyi Street, Guiyang, 550004, Guizhou, China
| | - Hongwei Duan
- Department of Anesthesiology, The Affiliated Pudong Hospital of Fudan University, No. 2800 Gongwei Road, Huinan Town, Pudong New Area 200120, Shanghai, China
| | - Kaiyuan Chen
- Translational Medicine Research Center, Clinical Medical School, Guizhou Medical University, No. 9, Beijing Road, Guiyang, 550004, Guizhou, China
| | - Chunlei Wen
- Translational Medicine Research Center, Clinical Medical School, Guizhou Medical University, No. 9, Beijing Road, Guiyang, 550004, Guizhou, China
| | - Ying Cao
- Translational Medicine Research Center, Clinical Medical School, Guizhou Medical University, No. 9, Beijing Road, Guiyang, 550004, Guizhou, China
| | - Hong Gao
- Translational Medicine Research Center, Clinical Medical School, Guizhou Medical University, No. 9, Beijing Road, Guiyang, 550004, Guizhou, China.
- Department of Equipment, The Affiliated Hospital of Guizhou Medical University, No. 28, Guiyi Street, Guiyang, 550004, Guizhou, China.
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2
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Forouzandehmehr M, Koivumäki JT, Hyttinen J, Paci M. A mathematical model of hiPSC cardiomyocytes electromechanics. Physiol Rep 2021; 9:e15124. [PMID: 34825519 PMCID: PMC8617339 DOI: 10.14814/phy2.15124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/18/2021] [Accepted: 11/02/2021] [Indexed: 01/21/2023] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are becoming instrumental in cardiac research, human-based cell level cardiotoxicity tests, and developing patient-specific care. As one of the principal functional readouts is contractility, we propose a novel electromechanical hiPSC-CM computational model named the hiPSC-CM-CE. This model comprises a reparametrized version of contractile element (CE) by Rice et al., 2008, with a new passive force formulation, integrated into a hiPSC-CM electrophysiology formalism by Paci et al. in 2020. Our simulated results were validated against in vitro data reported for hiPSC-CMs at matching conditions from different labs. Specifically, key action potential (AP) and calcium transient (CaT) biomarkers simulated by the hiPSC-CM-CE model were within the experimental ranges. On the mechanical side, simulated cell shortening, contraction-relaxation kinetic indices (RT50 and RT25 ), and the amplitude of tension fell within the experimental intervals. Markedly, as an inter-scale analysis, correct classification of the inotropic effects due to non-cardiomyocytes in hiPSC-CM tissues was predicted on account of the passive force expression introduced to the CE. Finally, the physiological inotropic effects caused by Verapamil and Bay-K 8644 and the aftercontractions due to the early afterdepolarizations (EADs) were simulated and validated against experimental data. In the future, the presented model can be readily expanded to take in pharmacological trials and genetic mutations, such as those involved in hypertrophic cardiomyopathy, and study arrhythmia trigger mechanisms.
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Affiliation(s)
| | - Jussi T. Koivumäki
- Faculty of Medicine and Health TechnologyTampere UniversityTampereFinland
| | - Jari Hyttinen
- Faculty of Medicine and Health TechnologyTampere UniversityTampereFinland
| | - Michelangelo Paci
- Faculty of Medicine and Health TechnologyTampere UniversityTampereFinland
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3
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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4
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Arteyeva NV. Dispersion of ventricular repolarization: Temporal and spatial. World J Cardiol 2020; 12:437-449. [PMID: 33014291 PMCID: PMC7509993 DOI: 10.4330/wjc.v12.i9.437] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 06/11/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023] Open
Abstract
Repolarization heterogeneity (RH) is an intrinsic property of ventricular myocardium and the reason for T-wave formation on electrocardiogram (ECG). Exceeding the physiologically based RH level is associated with appearance of life-threatening ventricular arrhythmias and sudden cardiac death. In this regard, an accurate and comprehensive evaluation of the degree of RH parameters is of importance for assessment of heart state and arrhythmic risk. This review is devoted to comprehensive consideration of RH phenomena in terms of electrophysiological processes underlying RH, cardiac electric field formation during ventricular repolarization, as well as clinical significance of RH and its reflection on ECG parameters. The formation of transmural, apicobasal, left-to-right and anterior-posterior gradients of action potential durations and end of repolarization times resulting from the heterogenous distribution of repolarizing ion currents and action potential morphology throughout the heart ventricles, and the different sensitivity of myocardial cells in different ventricular regions to the action of pharmacological agents, temperature, frequency of stimulation, etc., are being discussed. The review is focused on the fact that RH has different aspects – temporal and spatial, global and local; ECG reflection of various RH aspects and their clinical significance are being discussed. Strategies for comprehensive assessment of ventricular RH using different ECG indices reflecting various RH aspects are presented.
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Affiliation(s)
- Natalia V Arteyeva
- Laboratory of Cardiac Physiology, Institute of Physiology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences, Syktyvkar 167982, Russia
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5
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Abstract
The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.
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6
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Therapeutic effects of a taurine-magnesium coordination compound on experimental models of type 2 short QT syndrome. Acta Pharmacol Sin 2018; 39:382-392. [PMID: 29072257 DOI: 10.1038/aps.2017.86] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 05/19/2017] [Indexed: 01/21/2023] Open
Abstract
Short QT syndrome (SQTS) is a genetic arrhythmogenic disease that can cause malignant arrhythmia and sudden cardiac death. The current therapies for SQTS have application restrictions. We previously found that Mg· (NH2CH2CH2SO3)2· H2O, a taurine-magnesium coordination compound (TMCC) exerted anti-arrhythmic effects with low toxicity. In this study we established 3 different models to assess the potential anti-arrhythmic effects of TMCC on type 2 short QT syndrome (SQT2). In Langendorff guinea pig-perfused hearts, perfusion of pinacidil (20 μmol/L) significantly shortened the QT interval and QTpeak and increased rTp-Te (P<0.05 vs control). Subsequently, perfusion of TMCC (1-4 mmol/L) dose-dependently increased the QT interval and QTpeak (P<0.01 vs pinacidil). TMCC perfusion also reversed the rTp-Te value to the normal range. In guinea pig ventricular myocytes, perfusion of trapidil (1 mmol/L) significantly shortened the action potential duration at 50% (APD50) and 90% repolarization (APD90), which was significantly reversed by TMCC (0.01-1 mmol/L, P<0.05 vs trapidil). In HEK293 cells that stably expressed the outward delayed rectifier potassium channels (IKs), perfusion of TMCC (0.01-1 mmol/L) dose-dependently inhibited the IKs current with an IC50 value of 201.1 μmol/L. The present study provides evidence that TMCC can extend the repolarization period and inhibit the repolarizing current, IKs, thereby representing a therapeutic candidate for ventricular arrhythmia in SQT2.
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7
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Keskin M, Uzun AO, Börklü EB, Hayıroğlu Mİ, Türkkan C, Tekkeşin Aİ, Kozan Ö. The prognostic significance of early and late right precordial lead (V 4 R) ST-segment elevation in patients with acute anterior myocardial infarction. Ann Noninvasive Electrocardiol 2017; 23:e12513. [PMID: 29030902 DOI: 10.1111/anec.12513] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/13/2017] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The predictive significance of ST-segment elevation (STE) in lead V4 R in patients with anterior ST-segment elevation myocardial infarction (STEMI) has not been well-understood. In this study, we evaluated the prognostic value of early and late STE in lead V4 R in patients with anterior STEMI. METHODS A total 451 patients with anterior STEMI who treated with primary percutaneous coronary intervention (PPCI) were prospectively enrolled in this study. All patients were classified according to presence of STE (>1 mm) in lead V4 R at admission and/or 60 min after PPCI. Based on this classification, all patients were divided into three subgroups as no V4 R STE (Group 1), early but not late V4 R STE (Group 2) and late V4 R STE (Group 3). RESULTS In-hospital mortality had higher rates at group 2 and 3 and that had 2.1 and 4.1-times higher mortality than group 1. Late V4 R STE remained as an independent risk factor for cardiogenic shock (odds ratio [OR] 2.6; 95% confidence interval [CI] 1.9-4.3; p < .001) and in-hospital mortality (OR 2.3; 95% CI 1.8-4.1; p < .001). The 12-month overall survival for group 1, 2, and 3 were 91.1%, 82.4%, and 71.4% respectively. However, the long-term mortality also had the higher rate at group 3; late V4 R STE did not remain as an independent risk factor for long-term mortality (OR 1.5; 95% CI 0.8-4.1; p: .159). CONCLUSION Late V4 R STE in patients with anterior STEMI is strongly associated with poor prognosis. The record of late V4 R in patients with anterior STEMI has an important prognostic value.
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Affiliation(s)
- Muhammed Keskin
- Department of Cardiology, Sultan Abdulhamid Han Training and Research Hospital, Istanbul, Turkey
| | - Ahmet Okan Uzun
- Department of Cardiology, Dortyol State Hospital, Hatay, Turkey
| | - Edibe Betül Börklü
- Department of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, Turkey
| | - Mert İlker Hayıroğlu
- Department of Cardiology, Sultan Abdulhamid Han Training and Research Hospital, Istanbul, Turkey
| | - Ceyhan Türkkan
- Department of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, Turkey
| | - Ahmet İlker Tekkeşin
- Department of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital, Istanbul, Turkey
| | - Ömer Kozan
- Department of Cardiology, Sultan Abdulhamid Han Training and Research Hospital, Istanbul, Turkey
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8
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Edwards AG, Louch WE. Species-Dependent Mechanisms of Cardiac Arrhythmia: A Cellular Focus. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2017; 11:1179546816686061. [PMID: 28469490 PMCID: PMC5392019 DOI: 10.1177/1179546816686061] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/20/2016] [Indexed: 12/17/2022]
Abstract
Although ventricular arrhythmia remains a leading cause of morbidity and mortality, available antiarrhythmic drugs have limited efficacy. Disappointing progress in the development of novel, clinically relevant antiarrhythmic agents may partly be attributed to discrepancies between humans and animal models used in preclinical testing. However, such differences are at present difficult to predict, requiring improved understanding of arrhythmia mechanisms across species. To this end, we presently review interspecies similarities and differences in fundamental cardiomyocyte electrophysiology and current understanding of the mechanisms underlying the generation of afterdepolarizations and reentry. We specifically highlight patent shortcomings in small rodents to reproduce cellular and tissue-level arrhythmia substrate believed to be critical in human ventricle. Despite greater ease of translation from larger animal models, discrepancies remain and interpretation can be complicated by incomplete knowledge of human ventricular physiology due to low availability of explanted tissue. We therefore point to the benefits of mathematical modeling as a translational bridge to understanding and treating human arrhythmia.
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Affiliation(s)
- Andrew G Edwards
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway.,Center for Cardiological Innovation, Simula Research Laboratory, Lysaker, Norway.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo, Oslo, Norway
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9
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Srinivasan NT, Orini M, Simon RB, Providência R, Khan FZ, Segal OR, Babu GG, Bradley R, Rowland E, Ahsan S, Chow AW, Lowe MD, Taggart P, Lambiase PD. Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart. Am J Physiol Heart Circ Physiol 2016; 311:H545-54. [PMID: 27371682 PMCID: PMC5142177 DOI: 10.1152/ajpheart.00159.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/29/2016] [Indexed: 12/18/2022]
Abstract
Spatial variation of restitution in relation to varying stimulus site is poorly defined in the intact human heart. Repolarization gradients were shown to be dependent on site of activation with epicardial stimulation promoting significant transmural gradients. Steep restitution slopes were predominant in the normal ventricle. The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1–S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope −1.36 ± 1.9 and −0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic.
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Affiliation(s)
- Neil T Srinivasan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Michele Orini
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Ron B Simon
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Rui Providência
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Fakhar Z Khan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Oliver R Segal
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Girish G Babu
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Richard Bradley
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Edward Rowland
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Syed Ahsan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Anthony W Chow
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Martin D Lowe
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Pier D Lambiase
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
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10
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Frommeyer G, Eckardt L. Drug-induced proarrhythmia: risk factors and electrophysiological mechanisms. Nat Rev Cardiol 2015; 13:36-47. [PMID: 26194552 DOI: 10.1038/nrcardio.2015.110] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Drug-induced ventricular tachyarrhythmias can be caused by cardiovascular drugs, noncardiovascular drugs, and even nonprescription agents. They can result in arrhythmic emergencies and sudden cardiac death. If a new arrhythmia or aggravation of an existing arrhythmia develops during therapy with a drug at a concentration usually considered not to be toxic, the situation can be defined as proarrhythmia. Various cardiovascular and noncardiovascular drugs can increase the occurrence of polymorphic ventricular tachycardia of the 'torsade de pointes' type. Antiarrhythmic drugs, antimicrobial agents, and antipsychotic and antidepressant drugs are the most important groups. Age, female sex, and structural heart disease are important risk factors for the occurrence of torsade de pointes. Genetic predisposition and individual pharmacodynamic and pharmacokinetic sensitivity also have important roles in the generation of arrhythmias. An increase in spatial or temporal dispersion of repolarization and a triangular action-potential configuration have been identified as crucial predictors of proarrhythmia in experimental models. These studies emphasized that sole consideration of the QT interval is not sufficient to assess the proarrhythmic risk. In this Review, we focus on important triggers of proarrhythmia and the underlying electrophysiological mechanisms that can enhance or prevent the development of torsade de pointes.
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Affiliation(s)
- Gerrit Frommeyer
- Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Albert-Schweitzer Strasse 33, D-48149 Münster, Germany
| | - Lars Eckardt
- Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Albert-Schweitzer Strasse 33, D-48149 Münster, Germany
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11
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Arteyeva NV, Azarov JE, Vityazev VA, Shmakov DN. Action potential duration gradients in the heart ventricles and the cardiac electric field during ventricular repolarization (a model study). J Electrocardiol 2015; 48:678-85. [PMID: 25818745 DOI: 10.1016/j.jelectrocard.2015.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Indexed: 12/14/2022]
Abstract
BACKGROUND We simulated contributions of transmural, apicobasal, anteroposterior and interventricular action potential duration (APD) gradients to the body surface potential distribution (BSPD) with constant or varied magnitudes of the transmural and apicobasal gradients. METHODS Simulations were done in the framework of the discrete computer model of the rabbit heart ventricles on the basis of realistic activation sequence and APDs. The APD gradients were set constant at 20 ms or varied in the range of ±80 ms. RESULTS The apicobasal, transmural and interventricular APD gradients of 20 ms produced similar BSPDs, whereas the BSPD inversion was caused by the inverted apicobasal or transmural 80 ms gradients. The transmural APD gradient produced transversal and mainly apicobasal T-wave vectors due to wall curvature and cancellation effects. The "normal" transversal and apicobasal repolarization gradients were decreased and increased by activation sequence, respectively. CONCLUSION The different APD gradients contributed consistently to the development of BSPD.
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Affiliation(s)
- Natalia V Arteyeva
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50, Pervomayskaya St., Syktyvkar, Russia
| | - Jan E Azarov
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50, Pervomayskaya St., Syktyvkar, Russia; Department of Physiology, Medical Institute of Syktyvkar State University, 11, Babushkin St., Syktyvkar, Russia.
| | - Vladimir A Vityazev
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50, Pervomayskaya St., Syktyvkar, Russia; Department of Physiology, Medical Institute of Syktyvkar State University, 11, Babushkin St., Syktyvkar, Russia
| | - Dmitry N Shmakov
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50, Pervomayskaya St., Syktyvkar, Russia
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12
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Tusun E, Uluganyan M, Ugur M, Karaca G, Osman F, Koroglu B, Murat A, Ekmekci A, Uyarel H, Sahin O, Eren M, Bolca O. ST-segment elevation of right precordial lead (V4 R) is associated with multivessel disease and increased in-hospital mortality in acute anterior myocardial infarction patients. Ann Noninvasive Electrocardiol 2014; 20:362-7. [PMID: 25209301 DOI: 10.1111/anec.12199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND ST segment elevation of chest lead V4 R is associated with worse prognosis in acute inferior ST-elevation myocardial infarction (STEMI). This study tried to determine the relationship between ST elevation in the right precordial lead V4 R and acute anterior STEMI. METHODS Prospective study of 144 consecutive anterior STEMI patients: all had 15-lead ECG recordings (12 conventional leads and V3 R-V5 R) obtained. Patients were classified into two groups on the basis of presence (Group I, 50 patients) or absence (Group II, 94 patients) of ST-segment elevation ≥0.5 mm in lead V4 R. RESULTS Multivessel involvement was significantly higher in Group I compared with Group II (54% and 23% respectively, P < 0.001). Major adverse cardiac events and in-hospital mortality was also significantly higher for those in Group I (P < 0.02 for both). A significant correlation was found between in-hospital mortality and those in Group I (P = 0.03, OR: 6.27, CI: 1.22-32.3). There was an independent relationship between in-hospital mortality and V4 R-ST elevation (P = 0.03, OR: 11.64, CI: 1.3-27.4). CONCLUSION ST segment elevation in chest lead V4 R is associated with multivessel disease and increased in-hospital mortality in patients with anterior STEMI that had undergone primary percutaneous coronary intervention to the left anterior descending artery.
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Affiliation(s)
- Eyyup Tusun
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Mahmut Uluganyan
- Clinic of Cardiology, Kadirli Government Hospital, Osmaniye, Turkey
| | - Murat Ugur
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Gurkan Karaca
- Clinic of Cardiology, Osmancik Government Hospital, Corum, Turkey
| | - Faizel Osman
- Department of Cardiology, University Hospital Coventry, Coventry, United Kingdom
| | - Bayram Koroglu
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Ahmet Murat
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Ahmet Ekmekci
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Hüseyin Uyarel
- Clinic of Cardiology, Bezmialem University Hospital, Istanbul, Turkey
| | - Osman Sahin
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Mehmet Eren
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
| | - Osman Bolca
- Clinic of Cardiology, Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Center Training and Research Hospital, Istanbul, Turkey
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Barta K, Czifra Á, Kun C, Páll A, Kulcsár J, Paragh G, Lőrincz I, Padra TJ, Agarwal A, Zarjou A, Abolfazl Z, Balla J, Szabó Z. Hemodiafiltration beneficially affects QT interval duration and dispersion compared to hemodialysis. Clin Exp Nephrol 2014; 18:952-9. [PMID: 24590361 DOI: 10.1007/s10157-014-0950-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 02/14/2014] [Indexed: 02/04/2023]
Abstract
BACKGROUND/AIMS The prolongation of the QT interval and dispersion could predict ventricular arrhythmias. It is not yet established whether there is a difference between the effects of hemodialysis and hemodiafiltration on QT interval duration and dispersion. METHODS Data of thirty patients was investigated while they were receiving hemodiafiltration over a period of 3 months; then the same group of patients was evaluated during treatment with conventional hemodialysis for at least another 3 months. Ionic parameters and surface electrocardiograms (ECG) were analyzed five times during each session, and 2D, M-mode echocardiography and Holter ECGs were performed to acquire additional information. RESULTS QT interval duration (QTmax) and dispersion (QTd) showed a significant increase during hemodialysis, but not during hemodiafiltration. QTmax was 388.66 ± 31.81 ms at the beginning of hemodialysis and increased to 400.66 ± 39.12 ms even at the 30th minute (p < 0.05). QTd was found to be 31.33 ± 10.08 ms before the commencement of hemodialysis with the largest prolongation being seen at the 240th minute (51.33 ± 14.56 ms, p < 0.05). The occurrence of ventricular premature beats was significantly higher during hemodialysis (p = 0.018). The left atrial diameter significantly decreased at the end of hemodiafiltration (at the beginning 45.1 ± 5.25 mm, at the end 40.77 ± 5.76 mm; p < 0.05). CONCLUSION Our results suggest a beneficial effect of hemodiafiltration on the studied electrocardiographic parameters compared to hemodialysis. The larger decrease in the left atrial diameter suggests a more efficient intracardiac volume-decreasing potential of hemodiafiltration.
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Affiliation(s)
- Kitti Barta
- Division of Nephrology, Department of Medicine, Medical and Health Science Centre, University of Debrecen, Pf. 19. Nagyerdei Krt. 98, Debrecen, 4012, Hungary
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Ruan L, Quan X, Li L, Bai R, Ni M, Xu R, Zhang C. Increasing gap junction coupling suppresses ibutilide-induced torsades de pointes. Exp Ther Med 2014; 7:1279-1284. [PMID: 24940425 PMCID: PMC3991525 DOI: 10.3892/etm.2014.1601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 02/13/2014] [Indexed: 11/24/2022] Open
Abstract
Drug-induced torsades de pointes (TdP) is common with class III antiarrhythmic drugs. Increased transmural dispersion of repolarization (TDR) contributes significantly to the development of TdP. Gap junctions play an important role in maintaining TDR in long QT syndrome. The present study examined the effect of a gap junction enhancer, antiarrhythmic peptide 10 (AAP10), on ibutilide-induced TdP. Coronary-perfused rabbit ventricular wedge preparations were used to evaluate the effect of AAP10 on ibutilide-induced arrhythmia. Transmural electrocardiograms and action potentials were recorded simultaneously. Early afterdepolarizations (EADs), R-on-T extrasystole, TdP and changes in Tpeak-end (Tp-e) and the Tp-e/QT ratio were observed. Changes in the levels of non-phosphorylated connexin 43 (Cx43) were measured by immunoblotting. Compared with those in the control group, the QT interval, Tp-e/QT and incidence rates of EAD and TdP increased with augmented dephosphorylation in the ventricular wedge preparations perfused with ibutilide under conditions of hypokalemia and hypomagnesemia. In the presence of AAP10, the incidence rates of EAD and TdP were reduced and the Tp-e/QT ratio decreased, with a parallel reduction in the level of non-phosphorylated Cx43. The results indicate that AAP10 suppressed ibutilide-induced TdP under conditions of hypokalemia and hypomagnesemia by decreasing TDR. AAP10 reduced TDR, possibly by preventing the dephosphorylation of Cx43 and thereby increasing myocardial cell gap junction coupling.
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Affiliation(s)
- Lei Ruan
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xiaoqing Quan
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Liandong Li
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Rong Bai
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
| | - Mingke Ni
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Rende Xu
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Cuntai Zhang
- Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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Abstract
Late I Na is an integral part of the sodium current, which persists long after the fast-inactivating component. The magnitude of the late I Na is relatively small in all species and in all types of cardiomyocytes as compared with the amplitude of the fast sodium current, but it contributes significantly to the shape and duration of the action potential. This late component had been shown to increase in several acquired or congenital conditions, including hypoxia, oxidative stress, and heart failure, or due to mutations in SCN5A, which encodes the α-subunit of the sodium channel, as well as in channel-interacting proteins, including multiple β subunits and anchoring proteins. Patients with enhanced late I Na exhibit the type-3 long QT syndrome (LQT3) characterized by high propensity for the life-threatening ventricular arrhythmias, such as Torsade de Pointes (TdP), as well as for atrial fibrillation. There are several distinct mechanisms of arrhythmogenesis due to abnormal late I Na, including abnormal automaticity, early and delayed after depolarization-induced triggered activity, and dramatic increase of ventricular dispersion of repolarization. Many local anesthetic and antiarrhythmic agents have a higher potency to block late I Na as compared with fast I Na. Several novel compounds, including ranolazine, GS-458967, and F15845, appear to be the most selective inhibitors of cardiac late I Na reported to date. Selective inhibition of late I Na is expected to be an effective strategy for correcting these acquired and congenital channelopathies.
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Barajas-Martínez H, Hu D, Goodrow RJ, Joyce F, Antzelevitch C. Electrophysiologic characteristics and pharmacologic response of human cardiomyocytes isolated from a patient with hypertrophic cardiomyopathy. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2013; 36:1512-5. [PMID: 24117780 DOI: 10.1111/pace.12227] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/17/2013] [Accepted: 06/11/2013] [Indexed: 01/12/2023]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is the most common monogenic cardiac disorder encountered in the clinic. Data relative to the electrophysiologic characteristics and pharmacologic responsiveness of human tissues and cells isolated from patients with HCM are rare. As a consequence, cellular mechanisms underlying arrhythmogenicity are poorly understood. METHODS Cardiomyocytes were enzymatically dissociated from a septal myectomy surgically removed from a patient with obstructive HCM. Sharp microelectrodes and patch-clamp techniques were used to evaluate action potential and sodium channel current (INa ) characteristics. RESULTS Action potential morphology recorded was typical of an M cell, but with a longer than normal duration (APD) and a relatively steep APD-rate relationship. APD at all rates was significantly reduced following exposure to ranolazine (10 μM). Whole cell patch-clamp recording yielded robust peak INa and large late INa (1.1% of peak INa vs 0.1-0.2% in healthy controls). A large window current was observed as well. Ranolazine (10 μM) shifted steady-state V0.5 of inactivation by -8 mV, reduced late INa by 82%, and significantly diminished the window current. CONCLUSION Our results indicate the presence of cells with M-cell characteristics in the septum of the human heart, as has previously been described in the canine heart. They also point to an ameliorative effect of ranolazine to reduce augmented late INa and thus to reduce the prolonged APD in the setting of HCM. These results suggest a potential therapeutic role for ranolazine in HCM.
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Affiliation(s)
- Hector Barajas-Martínez
- Department of Molecular Genetics and Experimental Cardiology, Masonic Medical Research Laboratory, Utica, New York
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Shryock JC, Song Y, Rajamani S, Antzelevitch C, Belardinelli L. The arrhythmogenic consequences of increasing late INa in the cardiomyocyte. Cardiovasc Res 2013; 99:600-11. [PMID: 23752976 DOI: 10.1093/cvr/cvt145] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This review presents the roles of cardiac sodium channel NaV1.5 late current (late INa) in generation of arrhythmic activity. The assumption of the authors is that proper Na(+) channel function is necessary to the maintenance of the transmembrane electrochemical gradient of Na(+) and regulation of cardiac electrical activity. Myocyte Na(+) channels' openings during the brief action potential upstroke contribute to peak INa and initiate excitation-contraction coupling. Openings of Na(+) channels outside the upstroke contribute to late INa, a depolarizing current that persists throughout the action potential plateau. The small, physiological late INa does not appear to be critical for normal electrical or contractile function in the heart. Late INa does, however, reduce the net repolarizing current, prolongs action potential duration, and increases cellular Na(+) loading. An increase of late INa, due to acquired conditions (e.g. heart failure) or inherited Na(+) channelopathies, facilitates the formation of early and delayed afterpolarizations and triggered arrhythmias, spontaneous diastolic depolarization, and cellular Ca(2+) loading. These in turn increase the spatial and temporal dispersion of repolarization time and may lead to reentrant arrhythmias.
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Affiliation(s)
- John C Shryock
- Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Foster City, CA, USA
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Alexandre J, Schiariti M, Rouet R, Puddu PE. Rabbit ventricular myocardium undergoing simulated ischemia and reperfusion in a double compartment tissue bath: a model to investigate both antiarrhythmic and arrhythmogenic likelihood. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2013; 5:52-60. [PMID: 23525863 PMCID: PMC3601462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/16/2013] [Indexed: 06/02/2023]
Abstract
An ischemia/reperfusion-simulating model in rabbit tissue should be right oriented and clinically relevant to provide a non expensive approach for manipulations of currents involved in the repolarization process. Standard right ventricular guinea-pig (N=18) and newly investigated rabbit (N=12) myocardial strips were placed in a special perfusion chamber allowing partition into two segments independently superfused with oxygenated Tyrode's solution or a modified Tyrode's solution mimicking ischemia by: 1) increased extracellular potassium concentration (12 mmol/L), 2) decreased HCO3 (-) concentration (9 mmol/L), leading to a decrease in pH (6.90 ± 0.05), 3) decreased pO2 by replacement of 95% O2 and 5% CO2 by 95% N2 and 5% CO2 gas mixture, and 4) complete withdrawal of glucose. There were significant differences in rabbit as compared to guinea-pig preparations in baseline (p<0.02) and post-ischemic-like (p<0.01) APA and RMP with lower values in the formers, and lower post-ischemic Vmax in rabbit preparations (25±15 versus 97±83 V/s, p<0.01) but neither baseline nor post-ischemic-like or absolute changes in APD50, APD90 were different. In ischemia- and reperfusion-like phases, there were high proportions of single spontaneous repetitive responses, both in guinea-pig (respectively 50 and 89%) and rabbit preparations (respectively 67 and 92%). Guinea-pig preparations showed higher incidence of severe spontaneous repetitive responses (61 versus 17%, p<0.02). This rabbit model is proposed to investigate both anti- and pro-arrhythmic effects of drugs acting at various levels electrophysiologically, which may be obtained with great power and relatively few (around 10 per group) preparations. This model should now be tested pharmacologically.
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Affiliation(s)
| | - Michele Schiariti
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, Sapienza University of RomeViale del Policlinico 155, I-00161 Rome, Italy
| | - René Rouet
- Université de Caen Basse-Normandie, EA 4650 Signalisation, électrophysiologie et imagerie des lésions d’ischémie-reperfusion myocardiqueF-14000 Caen, France
| | - Paolo Emilio Puddu
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, Sapienza University of RomeViale del Policlinico 155, I-00161 Rome, Italy
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Arteyeva NV, Goshka SL, Sedova KA, Bernikova OG, Azarov JE. What does the T(peak)-T(end) interval reflect? An experimental and model study. J Electrocardiol 2013; 46:296.e1-8. [PMID: 23473669 DOI: 10.1016/j.jelectrocard.2013.02.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Indexed: 12/17/2022]
Abstract
BACKGROUND It is unclear whether the Tpeak-Tend interval is an index of the transmural or the total dispersion of repolarization. METHODS We examined the Tpeak-Tend interval using a computer model of the rabbit heart ventricles based on experimentally measured transmural, apicobasal, and interventricular gradients of action potential duration. RESULTS Experimentally measured activation-recovery intervals increased from apex to base, from the left ventricle to the right ventricle, and in the apical portion of the left ventricle from epicardium to endocardium and from the right side of septum to the left side. The simulated Tpeak corresponded to the earliest end of repolarization, whereas the Tend corresponded to the latest end of repolarization. The different components of the global repolarization dispersion were discerned by simulation. CONCLUSIONS The Tpeak-Tend interval corresponds to the global dispersion of repolarization with distinct contributions of the apicobasal and transmural action potential duration gradients and apicobasal difference in activation times.
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Affiliation(s)
- Natalia V Arteyeva
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50, Pervomayskaya st, Syktyvkar, Russia
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20
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Bieganowska K, Sawicka-Parobczyk M, Bieganowski M, Piskorski J. Tpeak -tend interval in 12-lead electrocardiogram of healthy children and adolescents tpeak -tend interval in childhood. Ann Noninvasive Electrocardiol 2013; 18:344-51. [PMID: 23879274 DOI: 10.1111/anec.12035] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Tpeak (Tp) to the Tend (Te) interval is an index of transmural dispersion of repolarization. Prolongation of this interval predisposes to life-threatening ventricular arrhythmias in long QT syndrome, polymorphic catecholaminergic ventricular tachycardia, Brugada syndrome and short QT syndrome and may be an indicator of increased risk of sudden cardiac death. Very little is known about TpTe interval in children and adolescents. METHODS In 131 healthy children (64 girls) aged from 2.3 to 18.5 years (mean 9.1 years) the RR, QT, JT and TpTe intervals were measured manually in all leads of resting electrocardiogram (ECG). The statistical analysis were performed. RESULTS TpTe intervals vary significantly (P < 0.0001) between individual leads-the longest were in lead V3 , the shortest ones in leads III and V1 . Boys had longer TpTe intervals, with statistically significant differences in leads I, aVR and precordial V2 -V6 . Greater values were also observed in older children. TpTe dispersion varied from 6 to 80 ms (mean 38.6 ms ± 14.6 ms, median 40 ms) with no gender differences and greater values in older subjects (P = 0.003). In most leads, higher TpTe/QT and TpTe/JT ratios were seen in boys regardless of age. The TpTe intervals lengthens with lowering heart rate. CONCLUSIONS In healthy children and adolescents, TpTe intervals vary between individual leads of ECG, with the longest in lead V3 . The TpTe interval is longer in boys and in older children and prolongs as heart rate decelerates. TpTe/QT and TpTe/JT ratios are higher in boys. TpTe interval should be measured in precordial leads.
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Affiliation(s)
- Katarzyna Bieganowska
- Cardiology Department of the Children's Memorial Health Institute, 04-730 Warsaw, Poland.
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Di Diego JM, Sicouri S, Myles RC, Burton FL, Smith GL, Antzelevitch C. Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations. J Mol Cell Cardiol 2012; 54:53-64. [PMID: 23142540 DOI: 10.1016/j.yjmcc.2012.10.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/22/2012] [Accepted: 10/29/2012] [Indexed: 01/06/2023]
Abstract
The electrophysiological heterogeneity that exists across the ventricular wall in the mammalian heart has long been recognized, but remains an area that is incompletely understood. Experimental studies of the mechanisms of arrhythmogenesis in the whole heart often examine the epicardial surface in isolation and thereby disregard transmural electrophysiology. Significant heterogeneity exists in the electrophysiological properties of cardiomyocytes isolated from different layers of the ventricular wall, and given that regional heterogeneities of membrane repolarization properties can influence the electrophysiological substrate for re-entry, the diversity of cell types and characteristics spanning the ventricular wall is important in the study of arrhythmogenesis. For these reasons, coronary-perfused left ventricular wedge preparations have been developed to permit the study of transmural electrophysiology in the intact ventricle. Since the first report by Yan and Antzelevitch in 1996, electrical recordings from the transmural surface of canine wedge preparations have provided a wealth of data regarding the cellular basis for the electrocardiogram, the role of transmural heterogeneity in arrhythmogenesis, and differences in the response of the different ventricular layers to drugs and neurohormones. Use of the wedge preparation has since been expanded to other species and more recently it has also been widely used in optical mapping studies. The isolated perfused wedge preparation has become an important tool in cardiac electrophysiology. In this review, we detail the methodology involved in recording both electrical and optical signals from the coronary-perfused wedge preparation and review the advances in cardiac electrophysiology achieved through study of the wedge.
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Affiliation(s)
- José M Di Diego
- Masonic Medical Research Laboratory, 2150 Bleecker St., Utica, NY 13501, USA
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22
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Barsheshet A, Hod H, Oieru D, Goldenberg I, Sandach A, Beigel R, Glikson M, Feinberg MS, Eldar M, Matetzky S. Right precordial lead (V4R) ST-segment elevation is associated with worse prognosis in patients with acute anterior myocardial infarction. J Am Coll Cardiol 2011; 58:548-9. [PMID: 21777755 DOI: 10.1016/j.jacc.2011.03.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 03/10/2011] [Accepted: 03/29/2011] [Indexed: 11/28/2022]
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Salama G, Akar FG. Deciphering Arrhythmia Mechanisms - Tools of the Trade. Card Electrophysiol Clin 2011; 3:11-21. [PMID: 21572551 PMCID: PMC3093299 DOI: 10.1016/j.ccep.2010.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Pathophysiological remodeling of cardiac function occurs at multiple levels, spanning the spectrum from molecular and sub-cellular changes to those occurring at the organ-system levels. Of key importance to arrhythmias are changes in electrophysiological and calcium handling properties at the tissue level. In this review, we discuss how high-resolution optical action potential and calcium transient imaging has advanced our understanding of basic arrhythmia mechanisms associated with multiple cardiovascular disorders, including the long QT syndrome, heart failure, and ischemia-reperfusion injury. We focus on the role of repolarization gradients (section 1) and calcium mediated triggers (section 2) in the initiation and maintenance of complex arrhythmias in these settings.
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Affiliation(s)
- Guy Salama
- University of Pittsburgh, The Cardiovascular Institute, Pittsburgh, PA, 15261
| | - Fadi G. Akar
- Mount Sinai School of Medicine, New York, NY 10029, Tel: 212-241-9251; FAX: 212-241-4080
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Meyer T, Stuerz K, Guenther E, Edamura M, Kraushaar U. Cardiac slices as a predictive tool for arrhythmogenic potential of drugs and chemicals. Expert Opin Drug Metab Toxicol 2010; 6:1461-75. [PMID: 21067457 DOI: 10.1517/17425255.2010.526601] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
IMPORTANCE OF THE FIELD cardiac arrhythmia represents one of the primary safety pharmacological concerns in drug development. The most prominent example is drug induced ventricular tachycardia of the Torsade des Pointes type. The mechanism how this type of arrhythmia develops is a complex multi-cellular phenomenon. It can only be insufficiently reflected by cellular or molecular assays. However, organ models - such as Langendorff hearts - or in vivo experiments are expensive and time consuming and not suitable for assays requiring an increased throughput. AREAS COVERED IN THIS REVIEW here, we describe and review an assay bridging the gap between cardiomyocyte based assays and organ based systems - cardiac slices. This assay is reviewed in direct comparison with established safety pharmacological assays. WHAT THE READER WILL GAIN while slices have played an important role in brain research for > 2 decades, cardiac slices are experiencing a renaissance due to the novel challenges in safety pharmacology just in the last few years. Cardiac slices can be cultured and recorded over several days. It is possible to access electrophysiological data with a high number of electrodes - up to 256 electrodes - embedded in the surface of a microelectrode array. TAKE HOME MESSAGE cardiac slices close the gap between cellular and organ based assays in cardiac safety pharmacology. The tissue properties of a functional cardiac syncytium are more accurately reflected by a slice rather than a single cell.
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Affiliation(s)
- Thomas Meyer
- Multi Channel Systems MCS GmbH, Aspenhaustr. 21, 72770 Reutlingen, Germany.
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Haugaa KH, Amlie JP, Berge KE, Leren TP, Smiseth OA, Edvardsen T. Transmural differences in myocardial contraction in long-QT syndrome: mechanical consequences of ion channel dysfunction. Circulation 2010; 122:1355-63. [PMID: 20855658 DOI: 10.1161/circulationaha.110.960377] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Long-QT syndrome (LQTS) is characterized by prolonged myocardial action potential duration. The longest action potential duration is reported in the endomyocardium and midmyocardium. Prolonged action potential duration in LQTS may cause prolonged cardiac contraction, which can be assessed by strain echocardiography. We hypothesized that myocardial contraction is most prolonged in subendocardial myofibers in LQTS patients and that inhomogeneous transmural contraction is related to the risk of spontaneous arrhythmia. METHODS AND RESULTS We included 101 genotyped LQTS mutation carriers and 35 healthy individuals. A history of cardiac arrhythmias was present in 48 mutations carriers, and 53 were asymptomatic. Myocardial contraction duration was assessed by strain echocardiography as time from the ECG Q wave to peak strain in 16 LV segments. Strain was assessed along the longitudinal axis, predominantly representing subendocardial fibers, and along the circumferential axis, representing midmyocardial fibers. Mean contraction duration was longer in LQTS mutation carriers compared with healthy individuals (445 ± 45 versus 390 ± 40 milliseconds; P<0.001) and longer in symptomatic compared with asymptomatic LQTS mutation carriers (460 ± 40 versus 425 ± 45 milliseconds; P<0.001). Contraction duration by longitudinal strain was longer than by circumferential strain in symptomatic LQTS patients (460 ± 45 versus 445±45 milliseconds; P=0.008) but not in asymptomatic patients and healthy individuals, indicating transmural mechanical dispersion. This time difference was present in a majority of LV segments and was most evident in patients with LQT2 and the Jervell and Lange-Nielsen syndrome. CONCLUSION Contraction duration in symptomatic LQTS mutation carriers was longer in the subendocardium than in the midmyocardium, indicating transmural mechanical dispersion, which was not present in asymptomatic and healthy individuals.
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