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Hirahara AM, Khan MS, Ishidoya Y, Smego D, Roman O, Ranjan R, Krueger L, Hoareau G, Selzman CH, Dosdall DJ. Canine Model of Ischemia-Induced Ventricular Tachycardia. J Surg Res 2024; 293:196-203. [PMID: 37778087 PMCID: PMC10840854 DOI: 10.1016/j.jss.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 08/16/2023] [Accepted: 09/05/2023] [Indexed: 10/03/2023]
Abstract
INTRODUCTION Despite advances in antiarrhythmia therapies, ventricular tachycardia (VT) is a leading cause of sudden cardiac death. Investigation into the characteristics and new treatments for this arrhythmia is required to improve outcomes and a reproducible model of VT would be useful in these endeavors. We therefore created a canine model of ischemia-induced VT. MATERIALS AND METHODS A pacing lead was implanted in the right ventricle in canines (n = 13) and the left anterior descending artery was occluded in two locations for 2 h and subsequently released to create an ischemia-reperfusion injury. In the 10 dogs that survived the first 48 h following the initial study, a terminal study was conducted 4-7 d later and VT was induced using premature stimulation or burst pacing through the right ventricle lead. The arrhythmia was terminated using either antitachycardia pacing or a defibrillatory shock. Multiple inductions into sustained VT were attempted. RESULTS Sustained VT was induced in eight of 10 dogs with an average cycle length of 335 ± 70 bpm. Multiple episodes of VT were induced. Episodes of VT exhibited different electrocardiogram morphologies and cycle lengths in individual animals. CONCLUSIONS This canine model provides a consistent technique for inducing multiple episodes of sustained VT. It may be useful for investigating VT mechanisms and testing novel therapeutics and treatments for patients with VT.
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Affiliation(s)
- Annie M Hirahara
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Muhammad S Khan
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Yuki Ishidoya
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Douglas Smego
- Division of Cardiothoracic Surgery, Department of Surgery, University of Utah, Salt Lake City, Utah
| | - Orvelin Roman
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Ravi Ranjan
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Lauren Krueger
- Office of Comparative Medicine, University of Utah, Salt Lake City, Utah
| | - Guillaume Hoareau
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Emergency Medicine, University of Utah, Salt Lake City, Utah
| | - Craig H Selzman
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Division of Cardiothoracic Surgery, Department of Surgery, University of Utah, Salt Lake City, Utah
| | - Derek J Dosdall
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Division of Cardiothoracic Surgery, Department of Surgery, University of Utah, Salt Lake City, Utah; Division of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, Utah.
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Kawada S, Morita H, Miyamoto M, Asada S, Nakagawa K, Nishii N. Ventricular arrhythmias induced by phase 2 reentry in a patient with J-wave syndrome. HeartRhythm Case Rep 2023; 9:629-633. [PMID: 37746567 PMCID: PMC10511901 DOI: 10.1016/j.hrcr.2023.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023] Open
Affiliation(s)
- Satoshi Kawada
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hiroshi Morita
- Department of Cardiovascular Therapeutics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Masakazu Miyamoto
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Saori Asada
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Koji Nakagawa
- Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Nobuhiro Nishii
- Department of Cardiovascular Therapeutics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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Moras E, Gandhi K, Narasimhan B, Brugada R, Brugada J, Brugada P, Krittanawong C. Genetic and Molecular Mechanisms in Brugada Syndrome. Cells 2023; 12:1791. [PMID: 37443825 PMCID: PMC10340412 DOI: 10.3390/cells12131791] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/15/2023] Open
Abstract
Brugada syndrome is a rare hereditary arrhythmia disorder characterized by a distinctive electrocardiogram pattern and an elevated risk of ventricular arrhythmias and sudden cardiac death in young adults. Despite recent advances, it remains a complex condition, encompassing mechanisms, genetics, diagnosis, arrhythmia risk stratification, and management. The underlying electrophysiological mechanism of Brugada syndrome requires further investigation, with current theories focusing on abnormalities in repolarization, depolarization, and current-load match. The genetic basis of the syndrome is strong, with mutations found in genes encoding subunits of cardiac sodium, potassium, and calcium channels, as well as genes involved in channel trafficking and regulation. While the initial discovery of mutations in the SCN5A gene provided valuable insights, Brugada syndrome is now recognized as a multifactorial disease influenced by several loci and environmental factors, challenging the traditional autosomal dominant inheritance model. This comprehensive review aims to provide a current understanding of Brugada syndrome, focusing on its pathophysiology, genetic mechanisms, and novel models of risk stratification. Advancements in these areas hold the potential to facilitate earlier diagnosis, improve risk assessments, and enable more targeted therapeutic interventions.
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Affiliation(s)
- Errol Moras
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Kruti Gandhi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Bharat Narasimhan
- Debakey Cardiovascular Institute, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Ramon Brugada
- Cardiology, Cardiac Genetics Clinical Unit, Hospital Universitari Josep Trueta, Hospital Santa Caterina, 17007 Girona, Spain
- Cardiovascular Genetics Center and Clinical Diagnostic Laboratory, Institut d’Investigació Biomèdica Girona-IdIBGi, 17190 Salt, Spain
| | - Josep Brugada
- Cardiovascular Institute, Hospital Clínic, 08036 Barcelona, Spain
- Pediatric Arrhythmia Unit, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- Department of Medicine, University of Barcelona, 08036 Barcelona, Spain
| | - Pedro Brugada
- Cardiovascular Division, Free University of Brussels (UZ Brussel) VUB, B-1050 Brussels, Belgium
- Medical Centre Prof. Brugada, B-9300 Aalst, Belgium
- Arrhythmia Unit, Helicopteros Sanitarios Hospital (HSH), Puerto Banús, 29603 Marbella, Spain
| | - Chayakrit Krittanawong
- Cardiology Division, NYU Langone Health and NYU School of Medicine, New York, NY 10016, USA
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Use of Flecainide in Stable Coronary Artery Disease: An Analysis of Its Safety in Both Nonobstructive and Obstructive Coronary Artery Disease. Am J Cardiovasc Drugs 2021; 21:563-572. [PMID: 34142347 DOI: 10.1007/s40256-021-00483-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/03/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Flecainide is a class IC antiarrhythmic drug that is contraindicated in patients who have a history of myocardial infarction, but its effect on mortality and risk of proarrhythmia in patients with stable obstructive and nonobstructive epicardial coronary artery disease (CAD) has not been assessed. OBJECTIVE We sought to compare the safety of flecainide administration in patients who had angiographic evidence of either no or minimal CAD versus nonobstructive CAD, and those who underwent nuclear stress testing with perfusion defects versus those without perfusion defects. METHODS We conducted a retrospective chart review of 348 patients who were treated with flecainide for at least 1 year duration and underwent evaluation for CAD with coronary angiography or myocardial perfusion imaging (MPI) stress testing within 3 months of initiating flecainide. We compared overall mortality and proarrhythmia between varying levels of CAD and perfusion defects. RESULTS There was a similar 10-year survival between those with no or minimal CAD, nonobstructive CAD, and obstructive CAD (p = 0.6). Additionally, there was no difference in arrhythmia burden, including sustained ventricular tachycardias or frequent premature ventricular contractions (> 5% daily burden; p = 0.25). There was also no increase in mortality among those who had reversible perfusion defects >0% compared with those without, among subjects who underwent MPI (p = 0.14). On subgroup analysis, there was no increased risk in all-cause mortality with any specific coronary artery involvement, or with obstructive multivessel CAD (p = 0.89). CONCLUSION Flecainide use is not associated with an increase in either all-cause mortality or ventricular arrhythmias in low-risk patients with stable nonobstructive CAD.
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Boukens BJ, Potse M, Coronel R. Fibrosis and Conduction Abnormalities as Basis for Overlap of Brugada Syndrome and Early Repolarization Syndrome. Int J Mol Sci 2021; 22:1570. [PMID: 33557237 PMCID: PMC7913989 DOI: 10.3390/ijms22041570] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 12/16/2022] Open
Abstract
Brugada syndrome and early repolarization syndrome are both classified as J-wave syndromes, with a similar mechanism of arrhythmogenesis and with the same basis for genesis of the characteristic electrocardiographic features. The Brugada syndrome is now considered a conduction disorder based on subtle structural abnormalities in the right ventricular outflow tract. Recent evidence suggests structural substrate in patients with the early repolarization syndrome as well. We propose a unifying mechanism based on these structural abnormalities explaining both arrhythmogenesis and the electrocardiographic changes. In addition, we speculate that, with increasing technical advances in imaging techniques and their spatial resolution, these syndromes will be reclassified as structural heart diseases or cardiomyopathies.
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Affiliation(s)
- Bastiaan J. Boukens
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam Cardiovascular Sciences, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
- Department of Medical Biology, Amsterdam University Medical Center, Amsterdam Cardiovascular Sciences, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Mark Potse
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, 33600 Bordeaux, France;
- UMR5251, Institut de Mathématiques de Bordeaux, Université de Bordeaux, 33400 Talence, France
- Carmen Team, INRIA Bordeaux—Sud-Ouest, 33400 Talence, France
| | - Ruben Coronel
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam Cardiovascular Sciences, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands;
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Abstract
Pharmacologic management of atrial fibrillation (AF) is a pressing problem. This arrhythmia afflicts >5 million individuals in the United States and prevalence is estimated to rise to 12 million by 2050. Although the pill-in-the-pocket regimen for self-administered AF cardioversion introduced over a decade ago has proven useful, significant drawbacks exist. Among these are the relatively long latency of effects in the range of hours along with potential for hypotension and other adverse effects. This experience prompted development of a new strategy for increasing plasma concentrations of antiarrhythmic drugs rapidly and for a limited time, namely, pulmonary delivery. In preclinical studies in Yorkshire pigs, intratracheal administration of flecainide was shown to cause a rapid, reproducible increase in plasma drug levels. Moreover, pulmonary delivery of flecainide converted AF to normal sinus rhythm by prolonging atrial depolarization, which slows intra-atrial conduction and seems to be directly correlated with efficacy in converting AF. The rapid rise in plasma flecainide levels optimizes its anti-AF effects while minimizing adverse influences on ventricular depolarization and contractility. A more concentrated and soluble formulation of flecainide using a novel cyclodextrin complex excipient reduced net drug delivery for AF conversion when compared to the acetate formulation. Inhalation of the beta-adrenergic blocking agent metoprolol slows ventricular rate and can also terminate AF. In human subjects, oral inhalation of flecainide acetate with a hand-held, breath-actuated nebulizer results in signature prolongation of the QRS complex without serious adverse events. Thus, pulmonary delivery is a promising advance in pharmacologic approach to management of AF.
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Hoogendijk MG, Géczy T, Yap SC, Szili-Torok T. Pathophysiological Mechanisms of Premature Ventricular Complexes. Front Physiol 2020; 11:406. [PMID: 32528299 PMCID: PMC7247859 DOI: 10.3389/fphys.2020.00406] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/06/2020] [Indexed: 11/29/2022] Open
Abstract
Premature ventricular complexes (PVCs) are the most common ventricular arrhythmia. Despite the high prevalence, the cause of PVCs remains elusive in most patients. A better understanding of the underlying pathophysiological mechanism may help to steer future research. This review aims to provide an overview of the potential pathophysiological mechanisms of PVCs and their differentiation.
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Affiliation(s)
- Mark G Hoogendijk
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Tamás Géczy
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Sing-Chien Yap
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Tamas Szili-Torok
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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Marum AA, Silva BA, Bortolotto AL, Silva AC, de Antonio VZ, Belardinelli L, Verrier RL. Optimizing flecainide plasma concentration profile for atrial fibrillation conversion while minimizing adverse ventricular effects by rapid, low-dose intratracheal or intravenous administration. Int J Cardiol 2019; 274:170-174. [PMID: 30217428 DOI: 10.1016/j.ijcard.2018.09.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/21/2018] [Accepted: 09/07/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND We investigated whether rapid administration of a low dose of flecainide, either intratracheally or intravenously (IV), could accelerate conversion of atrial fibrillation (AF) while reducing adverse ventricular effects. METHODS Flecainide was delivered via intratracheal administration at 1.5 mg/kg bolus and compared to IV infusion at 1.0 mg/kg over 2 min (lower-dose, rapid) and 2.0 mg/kg over 10 min (ESC guideline) in closed-chest, anesthetized Yorkshire pigs. Catheters were fluoroscopically positioned in right atrium to measure atrial depolarization (Pa) duration and left ventricle (LV) to measure QRS complex duration and contractility (LV dP/dt) during atrial pacing at 140 beats/min. Flecainide was delivered intratracheally via a catheter positioned at the bifurcation of the main bronchi. AF was induced by intrapericardial administration of acetylcholine followed by burst pacing. RESULTS Flecainide reduced AF duration similarly by intratracheal and IV delivery. Peak plasma levels were comparable but Tmax differed and coincided with peaks in Pa prolongation. The area under the curve indicating sustained plasma levels was greater for higher-dose, slow IV flecainide than for either intratracheal instillation (by 32%) or lower-dose, rapid IV infusion (by 88%). As a result, higher-dose, slow IV flecainide caused 58% (p < 0.03) and 48% (p < 0.006) greater increases in QRS complex duration and 61% and 96% (both, p < 0.02) greater reductions in contractility compared to intratracheal and lower-dose, rapid IV flecainide, respectively. CONCLUSION Lower-dose, rapid flecainide, delivered either intratracheally or IV, optimizes the plasma concentration profile for effective conversion of AF while minimizing adverse effects on QRS complex duration and LV contractility.
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Affiliation(s)
- Alexandre A Marum
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Bruna A Silva
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Alexandre L Bortolotto
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Anderson C Silva
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Victor Z de Antonio
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | | | - Richard L Verrier
- Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Environmental Sciences, Harvard School of Public Health, Boston, MA, United States of America; Harvard Medical School, Boston, MA, United States of America.
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Verrier RL, Bortolotto AL, Silva BA, Marum AA, Stocco FG, Evaristo E, de Antonio VZ, Silva AC, Belardinelli L. Accelerated conversion of atrial fibrillation to normal sinus rhythm by pulmonary delivery of flecainide acetate in a porcine model. Heart Rhythm 2018; 15:1882-1888. [DOI: 10.1016/j.hrthm.2018.06.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Indexed: 12/14/2022]
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10
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McPheeters MT, Wang YT, Werdich AA, Jenkins MW, Laurita KR. An infrared optical pacing system for screening cardiac electrophysiology in human cardiomyocytes. PLoS One 2017; 12:e0183761. [PMID: 28837652 PMCID: PMC5570338 DOI: 10.1371/journal.pone.0183761] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 08/10/2017] [Indexed: 01/05/2023] Open
Abstract
Human cardiac myocytes derived from pluripotent stem cells (hCM) have invigorated interest in genetic disease mechanisms and cardiac safety testing; however, the technology to fully assess electrophysiological function in an assay that is amenable to high throughput screening has lagged. We describe a fully contactless system using optical pacing with an infrared (IR) laser and multi-site high fidelity fluorescence imaging to assess multiple electrophysiological parameters from hCM monolayers in a standard 96-well plate. Simultaneous multi-site action potentials (FluoVolt) or Ca2+ transients (Fluo4-AM) were measured, from which high resolution maps of conduction velocity and action potential duration (APD) were obtained in a single well. Energy thresholds for optical pacing were determined for cell plating density, laser spot size, pulse width, and wavelength and found to be within ranges reported previously for reliable pacing. Action potentials measured using FluoVolt and a microelectrode exhibited the same morphology and rate of depolarization. Importantly, we show that this can be achieved accurately with minimal damage to hCM due to optical pacing or fluorescence excitation. Finally, using this assay we demonstrate that hCM exhibit reproducible changes in repolarization and impulse conduction velocity for Flecainide and Quinidine, two well described reference compounds. In conclusion, we demonstrate a high fidelity electrophysiological screening assay that incorporates optical pacing with IR light to control beating rate of hCM monolayers.
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Affiliation(s)
- Matthew T. McPheeters
- Pediatrics, Case Western Reserve University, Cleveland, Ohio, United States of America
- Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Yves T. Wang
- Pediatrics, Case Western Reserve University, Cleveland, Ohio, United States of America
- Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Andreas A. Werdich
- Brigham and Women's Hospital/Harvard Medical School, Cardiovascular Division, Boston, Massachusetts, United States of America
| | - Michael W. Jenkins
- Pediatrics, Case Western Reserve University, Cleveland, Ohio, United States of America
- Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Kenneth R. Laurita
- Brigham and Women's Hospital/Harvard Medical School, Cardiovascular Division, Boston, Massachusetts, United States of America
- Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio, United States of America
- Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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12
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Barot SK, Seslar SP, Dolgner S, Mazor SS. A case of neonatal single twin flecainide toxicity after therapeutic in utero exposure for fetal SVT. TOXICOLOGY COMMUNICATIONS 2017. [DOI: 10.1080/24734306.2017.1411322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Sabiha K. Barot
- Department of Emergency Medicine, University of Washington, Seattle, WA, USA
| | - Stephen P. Seslar
- Department of Pediatrics, Division of Pediatric Cardiology, Seattle Children's Hospital, University of Washington, Seattle, WA, USA
| | - Stephen Dolgner
- Department of Pediatrics, Division of Pediatric Cardiology, Seattle Children's Hospital, University of Washington, Seattle, WA, USA
| | - Suzan S. Mazor
- Department of Pediatrics, Division of Emergency Medicine, Seattle Children's Hospital, University of Washington, Seattle, WA, USA
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13
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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14
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Zhao YH, Huang HX, Liu P, Du YH, Wang P, Wang W, Wu Y, Wang L, Ma CS, Liu HR. β 1 -Adrenoceptor autoantibodies increase the susceptibility to ventricular arrhythmias involving abnormal repolarization in guinea-pigs. Exp Physiol 2016; 102:25-33. [PMID: 27862484 DOI: 10.1113/ep085778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 11/04/2016] [Indexed: 01/14/2023]
Abstract
NEW FINDINGS What is the central question of this study? High titres of autoantibodies against the second extracellular loop of the β1 -adrenergic receptor (β1 -AAs) can be detected in the sera of patients with ventricular arrhythmias, but a causal relationship between β1 -AAs and ventricular arrhythmias has not been established. What is the main finding and its importance? Monoclonal β1 -AAs (β1 -AR mAbs) were used in the experiments. We showed that β1 -AR mAbs increased susceptibility to ventricular arrhythmias and induced repolarization abnormalities. Antibody adsorption of β1 -AAs will be a potential new therapeutic strategy for ventricular arrhythmias in patients with high titres of β1 -AAs. High titres of autoantibodies against the second extracellular loop of the β1 -adrenergic receptor (β1 -AAs) can be detected in sera from patients with ventricular arrhythmias, but a causal relationship between β1 -AAs and ventricular arrhythmias has not been established. In this work, ECGs of guinea-pigs and isolated guinea-pig hearts were recorded. Ventricular tachycardia (VT) and ventricular fibrillation (VF) were evoked by programmed electrical stimulation of the left ventricular epicardium of isolated guinea-pig hearts. The monophasic action potential and effective refractory period of the left ventricle were recorded in paced isolated guinea-pig hearts. Furthermore, to increase the specificity, monoclonal autoantibodies against the second extracellular loop of the β1 -adrenergic receptor (β1 -AR mAbs) were used in all experiments. The results showed that β1 -AR mAbs induced premature ventricular contractions in guinea-pigs and isolated guinea-pig hearts. In addition, β1 -AR mAbs decreased the threshold of VT/VF and prolonged the duration of VT/VF. Furthermore, β1 -AR mAbs shortened the corrected QT interval and effective refractory period, and prolonged late-phase repolarization of the monophasic action potential (MAPD90-30 ). These changes in electrophysiological parameters might be attributed, at least in part, to the arrhythmogenicity of β1 -AR mAbs.
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Affiliation(s)
- Yu-Hui Zhao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China.,Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Hai-Xia Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Ping Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Yun-Hui Du
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Peng Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Wen Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Ye Wu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Li Wang
- Department of Physiology, School of Basic Medical Sciences, Shanxi Medical University, Shanxi, 030001, China
| | - Chang-Sheng Ma
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, National Clinical Research Center for Cardiovascular Diseases, Beijing, 100029, China
| | - Hui-Rong Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Metabolic Disturbance Related Cardiovascular Disease, Beijing, 100069, China
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15
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Justo F, Fuller H, Nearing BD, Rajamani S, Belardinelli L, Verrier RL. Inhibition of the cardiac late sodium current with eleclazine protects against ischemia-induced vulnerability to atrial fibrillation and reduces atrial and ventricular repolarization abnormalities in the absence and presence of concurrent adrenergic stimulation. Heart Rhythm 2016; 13:1860-7. [DOI: 10.1016/j.hrthm.2016.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Indexed: 12/19/2022]
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16
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Haghjoo M, Arya A, Emkanjoo Z, Sadr-Ameli MA. Clinical and Electrophysiologic Profile of Brugada Syndrome in Iranian Patients. Asian Cardiovasc Thorac Ann 2016; 13:241-6. [PMID: 16112997 DOI: 10.1177/021849230501300311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Clinical and electrophysiologic characteristics of 20 patients (15 males; mean age, 42 ± 9 years) with Brugada syndrome were studied. Electrocardiographic abnormalities (spontaneous in 6 and provoked in 14) were recognized in 5 symptomatic and 15 asymptomatic patients. Mean PR (188 ± 18 vs. 184 ± 24 ms) and QT (362 ± 34 vs. 382 ± 28 ms) intervals and ST-segment elevation (2.28 ± 0.42 vs. 2.70 ± 0.77 mm) were similar in both groups. The PR interval was slightly longer in males than females (191 ± 21 vs.168 ± 18 ms, p = 0.042), but ST-segment elevation (2.70 ± 0.78 vs. 2.24 ± 0.26 mm) was similar. The HV interval was longer in males than females (57 ± 4 vs. 50 ± 4 ms, p = 0.047). Ventricular arrhythmias were induced in 40% of asymptomatic patients. There was no significant difference in age, sex, PR interval, ST-segment elevation, or HV interval between inducible and non-inducible patients. A defibrillator was implanted in 8 patients. During 16 ± 2 months of follow-up, one symptomatic patient had appropriate device therapy. None of the asymptomatic and non-inducible patients experienced a cardiac event. Electrophysiologic data have no role in predicting inducibility in programmed stimulation.
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Affiliation(s)
- Majid Haghjoo
- Department of Pacemaker and Electrophysiology, Shahid Rajaie Cardiovascular Center, Mellat Park, Vali-E-Asr Avenue, Tehran 1996911151, Iran.
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Antzelevitch C, Patocskai B. Brugada Syndrome: Clinical, Genetic, Molecular, Cellular, and Ionic Aspects. Curr Probl Cardiol 2016; 41:7-57. [PMID: 26671757 PMCID: PMC4737702 DOI: 10.1016/j.cpcardiol.2015.06.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.
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Affiliation(s)
| | - Bence Patocskai
- Masonic Medical Research Laboratory, Utica, NY 13501
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
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18
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Barman M. Proarrhythmic Effects Of Antiarrhythmic Drugs: Case Study Of Flecainide Induced Ventricular Arrhythmias During Treatment Of Atrial Fibrillation. J Atr Fibrillation 2015; 8:1091. [PMID: 27957216 DOI: 10.4022/jafib.1091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 12/19/2015] [Accepted: 12/27/2015] [Indexed: 02/02/2023]
Abstract
PURPOSE Flecainide is a class 1C antiarrhythmic drug especially used for the management of supraventricular arrhythmia. Flecainide also has a recognized proarrhythmic effect in patients treated for ventricular tachycardia. It is used to treat a variety of cardiac arrhythmias including paroxysmal atrial fibrillation, paroxysmal supraventricular tachycardia and ventricular tachycardia. Flecainide has local anesthetic effects and belongs to the class 1C AADs that block sodium channels, thereby slowing conduction through the heart. It selectively increases anterograde and retrograde accessory pathway refractoriness. The action of flecainide in the heart prolongs the PR interval and widens the QRS complex. The proarrhythmic effects however noted are not widely reported. METHOD We report a case of paroxysmal atrial fibrillation with structurally normal heart who was treated with oral Flecainide. There were no adverse events and no QTc prolongation was noted on ECG. Despite subjective improvement a repeat Holter detected him to have multiple short non sustained ventricular arrhythmias. RESULTS Development of ventricular arrhythmias, salvos and non-sustained ventricular tachycardia after a month of initiation of oral flecainide detected by 24 hours ECG Holter lead to discontinuation of flecainide and subsequent early electrophysiological studies and successful ablation. CONCLUSION Initiation of oral Flecainide in a case of atrial fibrillation with subjective improvement and regular ECG monitoring, no QTc prolongation can still lead to development of dangerous ventricular arrhythmias. A cautious approach and thorough investigations and follow up are recommended.
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Affiliation(s)
- M Barman
- Department of Cardiology, Al Ahli Hospital, PO Box 6401, Doha, Qatar
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Tse G, Yeo JM. Conduction abnormalities and ventricular arrhythmogenesis: The roles of sodium channels and gap junctions. IJC HEART & VASCULATURE 2015; 9:75-82. [PMID: 26839915 PMCID: PMC4695916 DOI: 10.1016/j.ijcha.2015.10.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/19/2015] [Indexed: 01/12/2023]
Abstract
Ventricular arrhythmias arise from disruptions in the normal orderly sequence of electrical activation and recovery of the heart. They can be categorized into disorders affecting predominantly cellular depolarization or repolarization, or those involving action potential (AP) conduction. This article briefly discusses the factors causing conduction abnormalities in the form of unidirectional conduction block and reduced conduction velocity (CV). It then examines the roles that sodium channels and gap junctions play in AP conduction. Finally, it synthesizes experimental results to illustrate molecular mechanisms of how abnormalities in these proteins contribute to such conduction abnormalities and hence ventricular arrhythmogenesis, in acquired pathologies such as acute ischaemia and heart failure, as well as inherited arrhythmic syndromes.
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Affiliation(s)
- Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, SW7 2AZ, UK
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20
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Effects of neferine on Kv4.3 channels expressed in HEK293 cells and ex vivo electrophysiology of rabbit hearts. Acta Pharmacol Sin 2015; 36:1451-61. [PMID: 26592512 DOI: 10.1038/aps.2015.83] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/26/2015] [Indexed: 01/16/2023] Open
Abstract
AIM Neferine is an isoquinoline alkaloid isolated from seed embryos of Nelumbo nucifera (Gaertn), which has a variety of biological activities. In this study we examined the effects of neferine on Kv4.3 channels, a major contributor to the transient outward current (I(to)) in rabbit heart, and on ex vivo electrophysiology of rabbit hearts. METHODS Whole-cell Kv4.3 currents were recorded in HEK293 cells expressing human cardiac Kv4.3 channels using patch-clamp technique. Arterially perfused wedges of rabbit left ventricles (LV) were prepared, and transmembrane action potentials were simultaneously recorded from epicardial (Epi) and endocardial (Endo) sites with floating microelectrodes together with transmural electrocardiography (ECG). RESULTS Neferine (0.1-100 μmol/L) dose-dependently and reversibly inhibited Kv4.3 currents (the IC50 value was 8.437 μmol/L, and the maximal inhibition at 100 μmol/L was 44.12%). Neferine (10 μmol/L) caused a positive shift of the steady-state activation curve of Kv4.3 currents, and a negative shift of the steady-state inactivation curve. Furthermore, neferine (10 μmol/L) accelerated the inactivation but not the activation of Kv4.3 currents, and markedly slowed the recovery of Kv4.3 currents from inactivation. Neferine-induced blocking of Kv4.3 currents was frequency-dependent. In arterially perfused wedges of rabbit LV, neferine (1, 3, and 10 μmol/L) dose-dependently prolonged the QT intervals and action potential durations (APD) at both Epi and Endo sites, and caused dramatic increase of APD10 at Epi sites. CONCLUSION Neferine inhibits Kv4.3 channels likely by blocking the open state and inactivating state channels, which contributes to neferine-induced dramatic increase of APD10 at Epi sites of rabbit heart.
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CARNEIRO JULIANASARAN, BENTO AFONSOSALVES, BACIC DANILO, NEARING BRUCED, RAJAMANI SRIDHARAN, BELARDINELLI LUIZ, VERRIER RICHARDL. The Selective Cardiac Late Sodium Current Inhibitor GS-458967 Suppresses Autonomically Triggered Atrial Fibrillation in an Intact Porcine Model. J Cardiovasc Electrophysiol 2015; 26:1364-9. [DOI: 10.1111/jce.12824] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 08/18/2015] [Accepted: 08/24/2015] [Indexed: 12/19/2022]
Affiliation(s)
- JULIANA SARAN CARNEIRO
- Beth Israel Deaconess Medical Center; Boston Massachusetts USA
- Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - AFONSO S. ALVES BENTO
- Beth Israel Deaconess Medical Center; Boston Massachusetts USA
- Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - DANILO BACIC
- Beth Israel Deaconess Medical Center; Boston Massachusetts USA
- Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - BRUCE D. NEARING
- Beth Israel Deaconess Medical Center; Boston Massachusetts USA
- Harvard Medical School; Boston Massachusetts USA
| | | | | | - RICHARD L. VERRIER
- Beth Israel Deaconess Medical Center; Boston Massachusetts USA
- Harvard Medical School; Boston Massachusetts USA
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Basis for the Induction of Tissue-Level Phase-2 Reentry as a Repolarization Disorder in the Brugada Syndrome. BIOMED RESEARCH INTERNATIONAL 2015; 2015:197586. [PMID: 26583094 PMCID: PMC4637010 DOI: 10.1155/2015/197586] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/21/2015] [Accepted: 08/23/2015] [Indexed: 11/20/2022]
Abstract
Aims. Human action potentials in the Brugada syndrome have been characterized by delayed or even complete loss of dome formation, especially in the right ventricular epicardial layers. Such a repolarization pattern is believed to trigger phase-2 reentry (P2R); however, little is known about the conditions necessary for its initiation. This study aims to determine the specific mechanisms that facilitate P2R induction in Brugada-affected cardiac tissue in humans. Methods. Ionic models for Brugada syndrome in human epicardial cells were developed and used to study the induction of P2R in cables, sheets, and a three-dimensional model of the right ventricular free wall. Results. In one-dimensional cables, P2R can be induced by adjoining lost-dome and delayed-dome regions, as mediated by tissue excitability and transmembrane voltage profiles, and reduced coupling facilitates its induction. In two and three dimensions, sustained reentry can arise when three regions (delayed-dome, lost-dome, and normal epicardium) are present. Conclusions. Not only does P2R induction by Brugada syndrome require regions of action potential with delayed-dome and lost-dome, but in order to generate a sustained reentry from a triggered waveback multiple factors are necessary, including heterogeneity in action potential distribution, tissue coupling, direction of stimulation, the shape of the late plateau, the duration of lost-dome action potentials, and recovery of tissue excitability, which is predominantly modulated by tissue coupling.
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23
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Flecainide-induced prolongation of ventricular repolarization contributes to the proarrhythmic profile of action. Int J Cardiol 2015; 197:81-2. [DOI: 10.1016/j.ijcard.2015.06.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/18/2015] [Indexed: 11/20/2022]
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Apps A, Miller CP, Fellows S, Jones M. Cardiac devices with class 1C antiarrhythmics: a potentially toxic combination. BMJ Case Rep 2015; 2015:bcr-2015-210598. [PMID: 26286909 DOI: 10.1136/bcr-2015-210598] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A patient taking regular flecainide for paroxysmal atrial fibrillation presented with broad complex tachycardia and circulatory compromise. With no history of pacemaker insertion and no pacing spikes visible on the ECG, this was presumed to be ventricular tachycardia and treated with electrical cardioversion, leading to p-wave asystole. An indwelling pacemaker was now recognised and ventricular capture was eventually attained by significantly increasing ventricular lead output. Invasive haemodynamic support was required due to new ventricular systolic dysfunction. Pacing thresholds and ventricular function normalised within 72 h consistent with flecainide toxicity; levels were shown to be toxic. Pacemaker interrogation revealed evidence of an undiagnosed atrial flutter, at presentation this was likely slowed by flecainide toxicity to a rate below the pacemaker mode switch, such that it was tracked in the ventricle at the upper tracking rate (120 bpm). Cardioversion terminated the arrhythmia but raised the capture threshold of the ventricle above the maximum lead output.
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Affiliation(s)
- Andrew Apps
- Department of Cardiology, Buckinghamshire Healthcare NHS Trust, High Wycombe, Bucks, UK
| | | | - Sarah Fellows
- Department of Cardiology, Buckinghamshire Healthcare NHS Trust, High Wycombe, Bucks, UK
| | - Michael Jones
- Department of Cardiology, John Radcliffe Hospital, Oxford, UK
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Patocskai B, Antzelevitch C. Novel Therapeutic Strategies for the Management of Ventricular Arrhythmias Associated with the Brugada Syndrome. Expert Opin Orphan Drugs 2015; 3:633-651. [PMID: 27559494 PMCID: PMC4993532 DOI: 10.1517/21678707.2015.1037280] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by prominent J waves appearing as distinct coved type ST segment elevation in the right precordial leads of the ECG. It is associated with a high risk for sudden cardiac death. AREAS COVERED We discuss 1) ECG manifestations of BrS which can be unmasked or aggravated by sodium channel blockers, febrile states, vagotonic agents, as well as tricyclic and tetracyclic antidepressants; 2) Genetic basis of BrS; 3) Ionic and cellular mechanisms underlying BrS; 4) Therapy involving devices including an implantable cardioverter defibrillator (ICD); 5) Therapy involving radiofrequency ablation; and 6) Therapy involving pharmacological therapy which is aimed at producing an inward shift in the balance of the currents active during phase 1 of the right ventricular action potential either by boosting calcium channel current (isoproterenol, cilostazol and milrinone) or by inhibition of transient outward current Ito (quinidine, bepridil and the Chinese herb extract Wenxin Keli). EXPERT OPINION This review provides an overview of the clinical and molecular aspects of BrS with a focus on approaches to therapy. Available data suggest that agents capable of inhibiting the transient outward current Ito can exert an ameliorative effect regardless of the underlying cause.
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Affiliation(s)
- Bence Patocskai
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
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26
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Bonatti R, Silva AFG, Batatinha JAP, Sobrado LF, Machado AD, Varone BB, Nearing BD, Belardinelli L, Verrier RL. Selective late sodium current blockade with GS-458967 markedly reduces ischemia-induced atrial and ventricular repolarization alternans and ECG heterogeneity. Heart Rhythm 2014; 11:1827-35. [DOI: 10.1016/j.hrthm.2014.06.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Indexed: 12/19/2022]
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27
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Mashar M, Kwok AJ, Pinder R, Sabir I. The Brugada syndrome revisited. Trends Cardiovasc Med 2013; 24:191-6. [PMID: 24332084 DOI: 10.1016/j.tcm.2013.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 02/03/2023]
Abstract
The Brugada syndrome is a rare but well-defined cause of sudden cardiac death. The key underlying abnormality is a decrease in net depolarising current due to a genetic defect, though recent evidence also implicates structural abnormalities in some patients. Diagnosis requires a Brugada-type ECG as well as typical clinical features: such clinical considerations are currently key in guiding risk stratification and hence management. Whilst pharmacological therapies are under investigation, the only intervention with a robust evidence base remains insertion of an implantable cardioverter defibrillator. Further research will be required to allow more effective risk stratification and hence more rational therapy.
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Affiliation(s)
| | | | - Richard Pinder
- School of Public Health, Imperial College London, London, UK
| | - Ian Sabir
- Downing College, Cambridge, UK; Physiological Laboratory, Rayne Institute, University of Cambridge, St. Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.
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28
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Bohora S. Drug Therapy For Preventing Ventricular Arrhythmia In Brugada syndrome: Do We Have The Answers Yet? Indian Pacing Electrophysiol J 2013; 13:166-9. [PMID: 24130424 PMCID: PMC3775319 DOI: 10.1016/s0972-6292(16)30667-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Shomu Bohora
- U N Mehta Institute of Cardiology and Research Centre. Ahmedabad
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29
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Khoueiry G, Abi Rafeh N, Sullivan E, Saiful F, Jaffery Z, Kenigsberg DN, Krishnan SC, Khanal S, Bekheit S, Kowalski M. Do omega-3 polyunsaturated fatty acids reduce risk of sudden cardiac death and ventricular arrhythmias? A meta-analysis of randomized trials. Heart Lung 2013; 42:251-6. [PMID: 23714269 DOI: 10.1016/j.hrtlng.2013.03.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Omega-3 polyunsaturated fatty acids (PUFA) have demonstrated to have antiarrhythmic properties. However, randomized studies have shown inconsistent results. OBJECTIVE We aimed to analyze the effect of omega-3 PUFA on preventing potentially fatal ventricular arrhythmias and sudden cardiac death. METHODS Randomized trials comparing omega-3 PUFA to placebo and reporting sudden cardiac death (SCD) or first implanted cardioverter-defibrillator (ICD) event for ventricular tachycardia or fibrillation were included in this study. A meta-analysis using a random effects model was performed and results were expressed in terms of Odds Ratio (OR) and 95% Confidence Interval (CI) after evaluating for interstudy heterogeneity using I(2). The reported data were extracted on the basis of the intention-to-treat principle. RESULTS A total of 32,919 patients were included in nine trials; 16,465 patients received omega-3 PUFA and 16,454 received placebo. When comparing omega-3 PUFA to placebo, there was nonsignificant risk reduction of SCD or ventricular arrhythmias (OR = 0.82 [95% CI: 0.60-1.21], p = 0.21 I(2) = 49.7%). CONCLUSION Dietary supplementation with omega-3 PUFA does not affect the risk of SCD or ventricular arrhythmias.
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Affiliation(s)
- Georges Khoueiry
- Department of Cardiology, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756-0001, USA.
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Lü CM, Zhang ZX, Li L, Tang JM, Feng HX. Study on the relationship between myocardial ischemia assessed by 24-hour ambulatory electrocardiogram and ventricular premature beat originating from different positions in older adults. Eur Geriatr Med 2012. [DOI: 10.1016/j.eurger.2012.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
An early repolarization (ER) pattern in the ECG, distinguished by J-point elevation, slurring of the terminal part of the QRS and ST-segment elevation has long been recognized and considered to be a benign electrocardiographic manifestation. Experimental studies conducted over a decade ago suggested that some cases of ER may be associated with malignant arrhythmias. Validation of this hypothesis was provided by recent studies demonstrating that an ER pattern in the inferior or inferolateral leads is associated with increased risk for life-threatening arrhythmias, termed ER syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BS) and ERS, these syndromes have been grouped under the term "J wave syndromes". ERS and BS share similar ECG characteristics, clinical outcomes and risk factors, as well as a common arrhythmic platform related to amplification of I(to)-mediated J waves. Although BS and ERS differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression. Although most subjects exhibiting an ER pattern are at minimal to no risk, mounting evidence suggests that careful attention should be paid to subjects with "high risk" ER. The challenge ahead is to be able to identify those at risk for sudden cardiac death. Here I review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes.
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Affiliation(s)
- Charles Antzelevitch
- Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY 13501, USA.
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32
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Abstract
The J wave, a deflection that follows the QRS complex of the surface electrocardiogram, is usually partially buried in the R wave in humans, appearing as a J-point elevation. An early repolarization (ER) pattern characterized by J-point elevation, slurring of the terminal part of the QRS, and ST-segment elevation has long been recognized and considered to be totally benign. Recent studies have presented evidence demonstrating that an ER pattern in inferior leads or inferolateral leads is associated with increased risk for life-threatening arrhythmias, named early repolarization syndrome. Early repolarization syndrome and Brugada syndrome share similar electrocardiographic characteristics, clinical outcomes, risk factors, as well as a common arrhythmic platform related to amplification of I(to)-mediated J waves. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression, termed J-wave syndromes. Early repolarization syndrome has been proposed to be divided into 3 subtypes: type 1, displaying an ER pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and rarely seen in ventricular fibrillation survivors; type 2, displaying an ER pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; whereas type 3, displaying an ER pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms.
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Supplemental Studies for Cardiovascular Risk Assessment in Safety Pharmacology: A Critical Overview. Cardiovasc Toxicol 2011; 11:285-307. [DOI: 10.1007/s12012-011-9133-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Napolitano C, Antzelevitch C. Phenotypical manifestations of mutations in the genes encoding subunits of the cardiac voltage-dependent L-type calcium channel. Circ Res 2011; 108:607-18. [PMID: 21372292 DOI: 10.1161/circresaha.110.224279] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The L-type cardiac calcium channel (LTCC) plays a prominent role in the electric and mechanical function of the heart. Mutations in the LTCC have been associated with a number of inherited cardiac arrhythmia syndromes, including Timothy, Brugada, and early repolarization syndromes. Elucidation of the genetic defects associated with these syndromes has led to a better understanding of molecular and cellular mechanisms and the development of novel therapeutic approaches to dealing with the arrhythmic manifestations. This review provides an overview of the molecular structure and function of the LTCC, the genetic defects in these channels known to contribute to inherited disorders, and the underlying molecular and cellular mechanisms contributing to the development of life-threatening arrhythmias.
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Affiliation(s)
- Carlo Napolitano
- Executive Director and Director of Research, Gordon K. Moe Scholar, Masonic Medical Research Laboratory, 2150 Bleecker St, Utica, NY 13501, USA.
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35
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Martin CA, Zhang Y, Grace AA, Huang CLH. Increased right ventricular repolarization gradients promote arrhythmogenesis in a murine model of Brugada syndrome. J Cardiovasc Electrophysiol 2011; 21:1153-9. [PMID: 20384647 PMCID: PMC3084998 DOI: 10.1111/j.1540-8167.2010.01767.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Repolarization Gradients in Brugada Syndrome.Introduction: Brugada syndrome (BrS) is associated with loss of Na+ channel function and increased risks of a ventricular tachycardia exacerbated by flecainide but reduced by quinidine. Previous studies in nongenetic models have implicated both altered conduction times and repolarization gradients in this arrhythmogenicity. We compared activation latencies and spatial differences in action potential recovery between different ventricular regions in a murine Scn5a+/− BrS model, and investigated the effect of flecainide and quinidine upon these. Methods and Results: Langendorff-perfused wild-type and Scn5a+/− hearts were subjected to regular pacing and a combination of programmed electrical stimulation techniques. Monophasic action potentials were recorded from the right (RV) and left ventricular (LV) epicardium and endocardium before and following flecainide (10 μM) or quinidine (5 μM) treatment, and activation latencies measured. Transmural repolarization gradients were then calculated from the difference between neighboring endocardial and epicardial action potential durations (APDs). Scn5a+/− hearts showed decreased RV epicardial APDs, accentuating RV, but not LV, transmural gradients. This correlated with increased arrhythmic tendencies compared with wild-type. Flecainide increased RV transmural gradients, while quinidine decreased them, in line with their respective pro- and antiarrhythmic effects. In contrast, Scna5+/− hearts showed slowed conduction times in both RV and LV, exacerbated not only by flecainide but also by quinidine, in contrast to their differing effects on arrhythmogenesis. Conclusion: We use a murine genetic model of BrS to systematically analyze LV and RV action potential kinetics for the first time. This establishes a key role for accentuated transmural gradients, specifically in the RV, in its arrhythmogenicity. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1153-1159)
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge, United Kingdom.
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Antzelevitch C, Burashnikov A. Overview of Basic Mechanisms of Cardiac Arrhythmia. Card Electrophysiol Clin 2011; 3:23-45. [PMID: 21892379 DOI: 10.1016/j.ccep.2010.10.012] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Antzelevitch C, Dumaine R. Electrical Heterogeneity in the Heart: Physiological, Pharmacological and Clinical Implications. Compr Physiol 2011. [DOI: 10.1002/cphy.cp020117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Current-to-load mismatch, Brugada ECG pattern, and the associated arrhythmogenesis. Heart Rhythm 2011; 8:119-20. [DOI: 10.1016/j.hrthm.2010.09.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Indexed: 11/20/2022]
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Matthews GDK, Martin CA, Grace AA, Zhang Y, Huang CLH. Regional variations in action potential alternans in isolated murine Scn5a (+/-) hearts during dynamic pacing. Acta Physiol (Oxf) 2010; 200:129-46. [PMID: 20384594 DOI: 10.1111/j.1748-1716.2010.02138.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AIM clinical observations suggest that alternans in action potential (AP) characteristics presages breakdown of normal ordered cardiac electrical activity culminating in ventricular arrhythmogenesis. We compared such temporal nonuniformities in monophasic action potential (MAP) waveforms in left (LV) and right ventricular (RV) epicardia and endocardia of Langendorff-perfused murine wild-type (WT), and Scn5a(+/-) hearts modelling Brugada syndrome (BrS) for the first time. METHODS a dynamic pacing protocol imposed successively incremented steady pacing rates between 5.5 and 33 Hz. A signal analysis algorithm detected sequences of >10 beats showing alternans. Results were compared before and following the introduction of flecainide (10 microm) and quinidine (5 microm) known to exert pro- and anti-arrhythmic effects in BrS. RESULTS sustained and transient amplitude and duration alternans were both frequently followed by ventricular ectopic beats and ventricular tachycardia or fibrillation. Diastolic intervals (DIs) that coincided with onsets of transient (tr) or sustained (ss) alternans in MAP duration (DI*) and amplitude (DI') were determined. Kruskal-Wallis tests followed by Bonferroni-corrected Mann-Whitney U-tests were applied to these DI results sorted by recording site, pharmacological conditions or experimental populations. WT hearts showed no significant heterogeneities in any DI. Untreated Scn5a (+/-) hearts showed earlier onsets of transient but not sustained duration alternans in LV endocardium compared with RV endocardium or LV epicardium. Flecainide administration caused earlier onsets of both transient and sustained duration alternans selectively in the RV epicardium in the Scn5a (+/-) hearts. CONCLUSION these findings in a genetic model thus implicate RV epicardial changes in the arrhythmogenicity produced by flecainide challenge in previously asymptomatic clinical BrS.
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Affiliation(s)
- G D K Matthews
- Physiological Laboratory, University of Cambridge, Cambridge
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Abstract
The J wave, also referred to as an Osborn wave, is a deflection immediately following the QRS complex of the surface ECG. When partially buried in the R wave, the J wave appears as J-point elevation or ST-segment elevation. Several lines of evidence have suggested that arrhythmias associated with an early repolarization pattern in the inferior or mid to lateral precordial leads, Brugada syndrome, or arrhythmias associated with hypothermia and the acute phase of ST-segment elevation myocardial infarction are mechanistically linked to abnormalities in the manifestation of the transient outward current (I(to))-mediated J wave. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J-wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression that we propose be termed J-wave syndromes. This review summarizes our current state of knowledge concerning J-wave syndromes, bridging basic and clinical aspects. We propose to divide early repolarization syndrome into three subtypes: type 1, which displays an early repolarization pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and is rarely seen in ventricular fibrillation survivors; type 2, which displays an early repolarization pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; and type 3, which displays an early repolarization pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms.
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Kawano H, Matsumoto Y, Arakawa S, Satoh O, Hayano M. Premature atrial contraction induces torsades de pointes in a patient of Takotsubo cardiomyopathy with QT prolongation. Intern Med 2010; 49:1767-73. [PMID: 20720356 DOI: 10.2169/internalmedicine.49.3237] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Although the prognosis for patients with stress-induced cardiomyopathy (Takotsubo cardiomyopathy) is relatively good, some patients with this syndrome develop torsades de pointes, which can be fatal. The present report describes a patient with Takotsubo cardiomyopathy and torsades de pointes induced by premature atrial contraction associated with QT interval prolongation, hypokalemia and hypomagnesemia.
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Affiliation(s)
- Hiroaki Kawano
- Department of Cardiology, Nagasaki Rosai Hospital, Sasebo, Japan.
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Selective gamma-ketoaldehyde scavengers protect Nav1.5 from oxidant-induced inactivation. J Mol Cell Cardiol 2009; 48:352-9. [PMID: 19962379 DOI: 10.1016/j.yjmcc.2009.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 11/10/2009] [Accepted: 11/24/2009] [Indexed: 11/23/2022]
Abstract
The cardiac sodium channel (SCN5A, Na(V)1.5) is a key determinant of electrical impulse conduction in cardiac tissue. Acute myocardial infarction leads to diminished sodium channel availability, both because of decreased channel expression and because of greater inactivation of channels already present. Myocardial infarction leads to significant increases in reactive oxygen species and their downstream effectors including lipoxidation products. The effects of reactive oxygen species on Na(V)1.5 function in whole hearts can be modeled in cultured myocytes, where oxidants shift the availability curve of I(Na) to hyperpolarized potentials, decreasing cardiac sodium current at the normal activation threshold. We recently examined potential mediators of the oxidant-induced inactivation and found that one specific lipoxidation product, the isoketals, recapitulated the effects of oxidant on sodium currents. Isoketals are highly reactive gamma-ketoaldehydes formed by the peroxidation of arachidonic acid that covalently modify the lysine residues of proteins. We now confirm that exposure to oxidants induces lipoxidative modification of Na(V)1.5 and that the selective isoketal scavengers block voltage-dependent changes in sodium current by the oxidant tert-butylhydroperoxide, both in cells heterologously expressing Na(V)1.5 and in a mouse cardiac myocyte cell line (HL-1). Thus, inhibition of this lipoxidative modification pathway is sufficient to protect the sodium channel from oxidant induced inactivation and suggests the potential use of isoketal scavengers as novel therapeutics to prevent arrhythmogenesis during myocardial infarction.
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Instability in action potential morphology underlies phase 2 reentry: A mathematical modeling study. Heart Rhythm 2009; 6:813-22. [PMID: 19467510 DOI: 10.1016/j.hrthm.2009.02.043] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 02/25/2009] [Indexed: 11/22/2022]
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Suh WM, Fowler SJ, Yeh T, Krishnan SC. Successful catheter ablation of focal ventricular fibrillation originating from the right ventricle. J Interv Card Electrophysiol 2009; 26:139-42. [DOI: 10.1007/s10840-009-9368-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 02/09/2009] [Indexed: 10/20/2022]
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Ehrlich JR. Arrhythmogenic Brugada syndrome substrate: a proof of principle. Cardiovasc Res 2009; 81:635-6. [PMID: 19136529 DOI: 10.1093/cvr/cvp008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
The Brugada syndrome, first described as a new clinical entity in 1992, is widely recognized today as a form of inherited sudden cardiac arrest. The past 16 years witnessed a progressive increase in the number of reported cases and a dramatic proliferation of articles serving to define the clinical, genetic, cellular, ionic, and molecular aspects of the disease. This article provides a brief overview of recent advances in our understanding of the clinical presentation and molecular and cellular mechanisms and an update of existing controversies.
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Sabir IN, Killeen MJ, Grace AA, Huang CLH. Ventricular arrhythmogenesis: Insights from murine models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:208-18. [DOI: 10.1016/j.pbiomolbio.2008.10.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Clinical use of and future perspectives on antiarrhythmic drugs. Eur J Clin Pharmacol 2008; 64:1139-46. [PMID: 18762931 DOI: 10.1007/s00228-008-0555-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Accepted: 08/14/2008] [Indexed: 12/19/2022]
Abstract
Cardiac arrhythmias are associated with significant morbidity and mortality. Antiarrhythmic drug therapy was traditionally the mainstay of arrhythmia treatment; however, the limited efficacy and proarrhythmic potential of conventional antiarrhythmic drugs has generated interest in new approaches to the treatment of arrhythmias. Over the last decade, there has been improved characterization of the molecular pathways that culminate in arrhythmias. By analyzing mechanisms that increase susceptibility to arrhythmias in individuals with genetic syndromes, it might be possible to not only improve current therapies but also to develop novel approaches to treat and prevent common arrhythmias.
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Sicouri S, Antzelevitch C. Sudden cardiac death secondary to antidepressant and antipsychotic drugs. Expert Opin Drug Saf 2008; 7:181-94. [PMID: 18324881 DOI: 10.1517/14740338.7.2.181] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A number of antipsychotic and antidepressant drugs are known to increase the risk of ventricular arrhythmias and sudden cardiac death. Based largely on a concern over QT prolongation and the development of life-threatening arrhythmias, a number of antipsychotic drugs have been temporarily or permanently withdrawn from the market or their use restricted. Some antidepressants and antipsychotics have been linked to QT prolongation and the development of Torsade de pointes arrhythmias, whereas others have been associated with a Brugada syndrome phenotype and the development of polymorphic ventricular arrhythmias. This review examines the mechanisms and predisposing factors underlying the development of cardiac arrhythmias, and sudden cardiac death, associated with antidepressant and antipsychotic drugs in clinical use.
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Affiliation(s)
- Serge Sicouri
- Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, New York, NY 13501-1787, USA
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Abstract
Abnormalities in heart rhythm continue to cause high rates of illness and death. Better treatment could be provided by solving two main challenges: the early identification of patients who are at risk, and the characterization of molecular pathways that culminate in arrhythmias. By analysing mechanisms that increase susceptibility to arrhythmia in individuals with genetic syndromes, it might be possible to improve current therapies and to develop new ways to treat and prevent common arrhythmias.
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