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Geanacopoulos AT, Zielonka B, Fox MT, Kerr S, Chambers KD, Przybylski R, Burns MM. Pediatric antiarrhythmics and toxicity: A clinical review. J Am Coll Emerg Physicians Open 2024; 5:e13090. [PMID: 38371660 PMCID: PMC10869663 DOI: 10.1002/emp2.13090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/24/2023] [Accepted: 11/29/2023] [Indexed: 02/20/2024] Open
Abstract
Antiarrhythmic medications are fundamental in the acute and chronic management of pediatric arrhythmias. Particularly in the pediatric patient population, associated antiarrhythmic toxicities represent important potential adverse effects. Emergency medicine clinicians must be skilled in the detection, workup, and management of antiarrhythmic toxicity. This is a clinical review of the indications, pharmacology, adverse effects, and toxicologic treatment of antiarrhythmics commonly used in the pediatric patient population.
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Affiliation(s)
- Alexandra T. Geanacopoulos
- Division of Emergency MedicineBoston Children's HospitalBostonMassachusettsUSA
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
| | - Benjamin Zielonka
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
- Department of CardiologyBoston Children's HospitalBostonMassachusettsUSA
| | - Miriam T. Fox
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
| | - Sarah Kerr
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
| | | | - Robert Przybylski
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
- Department of CardiologyBoston Children's HospitalBostonMassachusettsUSA
| | - Michele M. Burns
- Division of Emergency MedicineBoston Children's HospitalBostonMassachusettsUSA
- Department of PediatricsHarvard Medical SchoolBostonMassachusettsUSA
- Harvard Medical Toxicology ProgramBoston Children's HospitalBostonMassachusettsUSA
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2
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Burashnikov A, Di Diego JM, Patocskai B, Echt DS, Belardinelli L, Antzelevitch C. Effect of Flecainide and Ibutilide Alone and in Combination to Terminate and Prevent Recurrence of Atrial Fibrillation. Circ Arrhythm Electrophysiol 2024; 17:e012454. [PMID: 38146652 DOI: 10.1161/circep.123.012454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/30/2023] [Indexed: 12/27/2023]
Abstract
BACKGROUND There is a need for improved approaches to rhythm control therapy of atrial fibrillation (AF). METHODS The effectiveness of flecainide (1.5 µmol/L) and ibutilide (20 nmol/L), alone and in combination, to cardiovert and prevent AF recurrence was studied in canine-isolated coronary-perfused right atrioventricular preparations. We also examined the safety of the combination of flecainide (1.5 µmol/L) and ibutilide (50 nmol/L) using canine left ventricular wedge preparations. RESULTS Sustained AF (>1 hour) was inducible in 100%, 60%, 20%, and 0% of atria in the presence of acetylcholine alone, acetylcholine+ibutilide, acetylcholine+flecainide, and acetylcholine+ibutilide+flecainide, respectively. When used alone, flecainide and ibutilide cardioverted sustained AF in 40% and 20% of atria, respectively, but in 100% of atria when used in combination. Ibutilide prolonged atrial and ventricular effective refractory period by 15% and 8%, respectively, at a cycle length of 500 ms (P<0.05 for both). Flecainide increased the effective refractory period in atria by 27% (P<0.01) but by only 2% in the ventricles. The combination of the 2 drugs lengthened the effective refractory period by 42% in atria (P<0.01) but by only 7% (P<0.05) in the ventricles. In left ventricular wedges, ibutilide prolonged QT and Tpeak-Tend intervals by 25 and 55%, respectively (P<0.05 for both; cycle length, 2000 ms). The addition of flecainide (1.5 µmol/L) partially reversed these effects (P<0.05 for both parameters versus ibutilide alone). Torsades de Pointes score was relatively high with ibutilide alone and low with the drug combination. CONCLUSIONS In our experimental model, a combination of flecainide and ibutilide significantly improves cardioversion and prevents the recurrence of AF compared with monotherapies with little to no risk for the development of long-QT-mediated ventricular proarrhythmia.
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Affiliation(s)
- Alexander Burashnikov
- Lankenau Institute for Medical Research, Wynnewood, PA (A.B., J.M.D.D., B.P., C.A.)
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA (A.B., C.A.)
| | - José M Di Diego
- Lankenau Institute for Medical Research, Wynnewood, PA (A.B., J.M.D.D., B.P., C.A.)
| | - Bence Patocskai
- Lankenau Institute for Medical Research, Wynnewood, PA (A.B., J.M.D.D., B.P., C.A.)
| | - Debra S Echt
- InCarda Therapeutics, Inc, Newark, CA (D.S.E., L.B.)
| | | | - Charles Antzelevitch
- Lankenau Institute for Medical Research, Wynnewood, PA (A.B., J.M.D.D., B.P., C.A.)
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA (A.B., C.A.)
- Lankenau Heart Institute, Main Line Health System, Wynnewood, PA (C.A.)
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Gao H, Yang F, Sattari K, Du X, Fu T, Fu S, Liu X, Lin J, Sun Y, Yao J. Bioinspired two-in-one nanotransistor sensor for the simultaneous measurements of electrical and mechanical cellular responses. SCIENCE ADVANCES 2022; 8:eabn2485. [PMID: 36001656 PMCID: PMC9401615 DOI: 10.1126/sciadv.abn2485] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 07/11/2022] [Indexed: 05/21/2023]
Abstract
The excitation-contraction dynamics in cardiac tissue are the most important physiological parameters for assessing developmental state. We demonstrate integrated nanoelectronic sensors capable of simultaneously probing electrical and mechanical cellular responses. The sensor is configured from a three-dimensional nanotransistor with its conduction channel protruding out of the plane. The structure promotes not only a tight seal with the cell for detecting action potential via field effect but also a close mechanical coupling for detecting cellular force via piezoresistive effect. Arrays of nanotransistors are integrated to realize label-free, submillisecond, and scalable interrogation of correlated cell dynamics, showing advantages in tracking and differentiating cell states in drug studies. The sensor can further decode vector information in cellular motion beyond typical scalar information acquired at the tissue level, hence offering an improved tool for cell mechanics studies. The sensor enables not only improved bioelectronic detections but also reduced invasiveness through the two-in-one converging integration.
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Affiliation(s)
- Hongyan Gao
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Feiyu Yang
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Kianoosh Sattari
- Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA
| | - Xian Du
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Tianda Fu
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Shuai Fu
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Xiaomeng Liu
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Jian Lin
- Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA
| | - Yubing Sun
- Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, Amherst, MA 01003, USA
- Department of Biomedical Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
| | - Jun Yao
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, Amherst, MA 01003, USA
- Department of Biomedical Engineering, University of Massachusetts, Amherst, Amherst, MA 01003, USA
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4
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Osadchii OE. Electrocardiographic marker of the cardiac action potential triangulation induced by antiarrhythmic drugs in perfused guinea-pig heart. Exp Physiol 2022; 107:864-878. [PMID: 35561081 DOI: 10.1113/ep090349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/09/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Can triangular appearance of ventricular action potential, indicating proarrhythmic profile of antiarrhythmic agent, be approximated by specific changes on ECG? What is the main finding and its importance? The triangulation of the ventricular action potential seen when antiarrhythmic drugs induce a greater lengthening of the late repolarization compared to the initial repolarization in epicardium, is closely approximated by a greater prolongation of the T wave upslope relative to the interval between the J point and the start of the T wave (the JTstart interval) on ECG. These findings may improve the power of ECG assessments in predicting the drug-induced arrhythmia resulting from slowed phase 3 repolarization. ABSTRACT Antiarrhythmic drugs prescribed to treat atrial fibrillation can occasionally precipitate ventricular tachyarrhythmia through a prominent slowing of the phase 3 repolarization. The latter results in the triangular shape of ventricular action potential, indicating high arrhythmic risks. However, clinically, the utilility of triangulation assessments for predicting arrhythmia is limited owing to the invasive nature of the ventricular action potential recordings. This study examined whether the triangulation effect can be detected indirectly from ECG analysis. Epicardial monophasic action potentials and ECG were simultaneously recorded in perfused guinea-pig hearts. With antiarrhythmics (dofetilide, quinidine, procainamide and flecainide), a prolongation of the initial repolarization seen in the action potential recordings was closely approximated by lengthening of the interval bewteen the J point and the start of the T wave (the JTstart interval) on ECG, whereas a prolongation of the late repolarization was paralleled by widening of the T wave upslope. Dofetilide, quinidine and procainamide induced a prominent slowing of the phase 3 repolarization in epicardium, leading to triangulation of the action potential. These effects were accompanied by a greater prolongation of the T wave upslope compared to the JTstart interval. Flecainide elicited a proportional prolongation of the initial and the late ventricular repolarization, and therefore failed to induce triangulation, based on analysis of both epicardial action potential and ECG profiles. Collectively, these findings suggest that the ratio between the durations of the T wave upslope and the JTstart interval may represent ECG metric of the ventricular action potential triangulation induced by antiarrhythmic drugs. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Oleg E Osadchii
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark.,Department of Pharmacology, Kuban State Medical University, Sedin Street 4, Krasnodar, 350063, Russia
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5
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O' Brien S, Holmes AP, Johnson DM, Kabir SN, O' Shea C, O' Reilly M, Avezzu A, Reyat JS, Hall AW, Apicella C, Ellinor PT, Niederer S, Tucker NR, Fabritz L, Kirchhof P, Pavlovic D. Increased atrial effectiveness of flecainide conferred by altered biophysical properties of sodium channels. J Mol Cell Cardiol 2022; 166:23-35. [PMID: 35114252 DOI: 10.1016/j.yjmcc.2022.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/13/2022] [Accepted: 01/26/2022] [Indexed: 11/25/2022]
Abstract
Atrial fibrillation (AF) affects over 1% of the population and is a leading cause of stroke and heart failure in the elderly. A feared side effect of sodium channel blocker therapy, ventricular pro-arrhythmia, appears to be relatively rare in patients with AF. The biophysical reasons for this relative safety of sodium blockers are not known. Our data demonstrates intrinsic differences between atrial and ventricular cardiac voltage-gated sodium currents (INa), leading to reduced maximum upstroke velocity of action potential and slower conduction, in left atria compared to ventricle. Reduced atrial INa is only detected at physiological membrane potentials and is driven by alterations in sodium channel biophysical properties and not by NaV1.5 protein expression. Flecainide displayed greater inhibition of atrial INa, greater reduction of maximum upstroke velocity of action potential, and slowed conduction in atrial cells and tissue. Our work highlights differences in biophysical properties of sodium channels in left atria and ventricles and their response to flecainide. These differences can explain the relative safety of sodium channel blocker therapy in patients with atrial fibrillation.
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Affiliation(s)
- Sian O' Brien
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Andrew P Holmes
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK; School of Biomedical Sciences, Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Daniel M Johnson
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK; School of Life, Health and Chemical Sciences, The Open University, Walton Hall, Milton Keynes, UK
| | - S Nashitha Kabir
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Christopher O' Shea
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Molly O' Reilly
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Adelisa Avezzu
- School of Biomedical Engineering & Imaging Sciences, Kings' College London, London, UK
| | - Jasmeet S Reyat
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Amelia W Hall
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02129, USA; Cardiovascular Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Clara Apicella
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK
| | - Patrick T Ellinor
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02129, USA; Cardiovascular Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Steven Niederer
- School of Biomedical Engineering & Imaging Sciences, Kings' College London, London, UK
| | - Nathan R Tucker
- Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02129, USA; Cardiovascular Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Masonic Medical Research Institute, Utica, NY, 13501, USA
| | - Larissa Fabritz
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK; University Center of Cardiovascular Science, University Heart and Vascular Center UKE, Hamburg, Germany; Department of Cardiology, University Heart and Vascular Center UKE, Hamburg, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany
| | - Paulus Kirchhof
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK; Department of Cardiology, University Heart and Vascular Center UKE, Hamburg, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany
| | - Davor Pavlovic
- Institute of Cardiovascular Science, University of Birmingham, Birmingham, UK.
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Flecainide in Ventricular Arrhythmias: From Old Myths to New Perspectives. J Clin Med 2021; 10:jcm10163696. [PMID: 34441994 PMCID: PMC8397118 DOI: 10.3390/jcm10163696] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/10/2021] [Accepted: 08/18/2021] [Indexed: 11/21/2022] Open
Abstract
Flecainide is an IC antiarrhythmic drug (AAD) that received in 1984 Food and Drug Administration approval for the treatment of sustained ventricular tachycardia (VT) and subsequently for rhythm control of atrial fibrillation (AF). Currently, flecainide is mainly employed for sinus rhythm maintenance in AF and the treatment of idiopathic ventricular arrhythmias (IVA) in absence of ischaemic and structural heart disease on the basis of CAST data. Recent studies enrolling patients with different structural heart diseases demonstrated good effectiveness and safety profile of flecainide. The purpose of this review is to assess current evidence for appropriate and safe use of flecainide, 30 years after CAST data, in the light of new diagnostic and therapeutic tools in the field of ischaemic and non-ischaemic heart disease.
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7
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Kodirov SA, Brachmann J, Safonova TA, Zhuravlev VL. Inactivation of Native K Channels. J Membr Biol 2021; 255:13-31. [PMID: 34383081 DOI: 10.1007/s00232-021-00195-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 06/30/2021] [Indexed: 01/12/2023]
Abstract
We have experimented with isolated cardiomyocytes of mollusks Helix. During the whole-cell patch-clamp recordings of K+ currents a considerable decrease in amplitude was observed upon repeated voltage steps at 0.96 Hz. For these experiments, ventricular cells were depolarized to identical + 20 mV from a holding potential of - 50 mV. The observed spontaneous inhibition of outward currents persisted in the presence of 4-aminopyridine, tetraethylammonium chloride or E-4031, the selective class III antiarrhythmic agent that blocks HERG channels. Similar tendency was retained when components of currents sensitive to either 4-AP or TEA were mathematically subtracted. Waveforms of currents sensitive to 1 and 10 micromolar concentration of E-4031 were distinct comprising prevailingly those activated during up to 200 ms pulses. The outward current activated by a voltage ramp at 60 mV x s-1 rate revealed an inward rectification around + 20 mV. This feature closely resembles those of the mammalian cardiac delayed rectifier IKr.
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Affiliation(s)
- Sodikdjon A Kodirov
- Department of Cardiology, Medical University Hospital Heidelberg, 69120, Heidelberg, Germany. .,Department of General Physiology, Saint Petersburg University, 199034, Saint Petersburg, Russia. .,Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA. .,Department of Biophysics, Saint Petersburg University, 199034, Saint Petersburg, Russia. .,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisboa, Portugal.
| | - Johannes Brachmann
- Department of Cardiology, Medical University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Tatiana A Safonova
- Department of General Physiology, Saint Petersburg University, 199034, Saint Petersburg, Russia
| | - Vladimir L Zhuravlev
- Department of Cardiology, Medical University Hospital Heidelberg, 69120, Heidelberg, Germany.,Department of General Physiology, Saint Petersburg University, 199034, Saint Petersburg, Russia
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8
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Huang M, Liao Z, Li X, Yang Z, Fan X, Li Y, Zhao Z, Lang S, Cyganek L, Zhou X, Akin I, Borggrefe M, El-Battrawy I. Effects of Antiarrhythmic Drugs on hERG Gating in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes From a Patient With Short QT Syndrome Type 1. Front Pharmacol 2021; 12:675003. [PMID: 34025432 PMCID: PMC8138577 DOI: 10.3389/fphar.2021.675003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/26/2021] [Indexed: 12/17/2022] Open
Abstract
Aims: The short QT syndrome type 1 (SQT1) is linked to hERG channel mutations (e.g., N588K). Drug effects on hERG channel gating kinetics in SQT1-cells have not been investigated. Methods: This study used hiPSC-CMs of a healthy donor and a SQT1-patient carrying the N588K mutation and patch clamp to examine the drug effects on hERG channel gating kinetics. Results: Ajmaline, amiodarone, ivabradine, flecainide, quinidine, mexiletine and ranolazine inhibited the hERG channel current (IKr) less strongly in hiPSC-CMs from the SQTS1-patient (SQT1-hiPSC-CMs) comparing with cells from the healthy donor (donor-hiPSC-CMs). Quinidine and mexiletine reduced, but ajmaline, amiodarone, ivabradine and ranolazine increased the time to peak of IKr similarly in SQT1-hiPSC-CMs and donor-hiPSC-CMs. Although regarding the shift of activation and inactivation curves, tested drugs showed differential effects in donor- and SQT1-hiPSC-CMs, quinidine, ajmaline, ivabradine and mexiletine but not amiodarone, flecainide and ranolazine reduced the window current in SQT1-hiPSC-CMs. Quinidine, ajmaline, ivabradine and mexiletine differentially changed the time constant of recovery from inactivation, but all of them increased the time constant of deactivation in SQT1-hiPSC-CMs. Conclusion: The window current-reducing and deactivation-slowing effects may be important for the antiarrhythmic effect of ajmaline, ivabradine, quinidine and mexiletine in SQT1-cells. This information may be helpful for selecting drugs for treating SQT1-patients with hERG channel mutation.
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Affiliation(s)
- Mengying Huang
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Zhenxing Liao
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,North Sichuan Medical College, Nanchong, China
| | - Xin Li
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Zhen Yang
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,North Sichuan Medical College, Nanchong, China
| | - Xuehui Fan
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yingrui Li
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Zhihan Zhao
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Siegfried Lang
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Lukas Cyganek
- DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany.,Stem Cell Unit, Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
| | - Xiaobo Zhou
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Ibrahim Akin
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Martin Borggrefe
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany
| | - Ibrahim El-Battrawy
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Sites, Heidelberg-Mannheim and Göttingen, Mannheim, Germany
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Lavalle C, Magnocavallo M, Straito M, Santini L, Forleo GB, Grimaldi M, Badagliacca R, Lanata L, Ricci RP. Flecainide How and When: A Practical Guide in Supraventricular Arrhythmias. J Clin Med 2021; 10:1456. [PMID: 33918105 PMCID: PMC8036302 DOI: 10.3390/jcm10071456] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/19/2021] [Accepted: 03/29/2021] [Indexed: 11/29/2022] Open
Abstract
Transcatheter ablation was increasingly and successfully used to treat symptomatic drug refractory patients affected by supraventricular arrhythmias. Antiarrhythmic drug treatment still plays a major role in patient management, alone or combined with non-pharmacological therapies. Flecainide is an IC antiarrhythmic drug approved in 1984 from the Food and Drug Administration for the suppression of sustained ventricular tachycardia and later for acute cardioversion of atrial fibrillation and for sinus rhythm maintenance. Currently, flecainide is mostly used for sinus rhythm maintenance in atrial fibrillation (AF) patients without structural cardiomyopathy although recent studies enrolling different patient populations have demonstrated a good effectiveness and safety profile. How should we interpret the results of the CAST after the latest evidence? Is it possible to expand the indications of flecainide, and therefore, its use? This review aims to highlight the main characteristics of flecainide, as well as its optimal clinical use, delineating drug indications and contraindications and appropriate monitoring, based on the most recent evidence.
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Affiliation(s)
- Carlo Lavalle
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, “Sapienza” University of Rome, Policlinico Umberto I, 00161 Rome, Italy; (M.M.); (M.S.); (R.B.)
| | - Michele Magnocavallo
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, “Sapienza” University of Rome, Policlinico Umberto I, 00161 Rome, Italy; (M.M.); (M.S.); (R.B.)
| | - Martina Straito
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, “Sapienza” University of Rome, Policlinico Umberto I, 00161 Rome, Italy; (M.M.); (M.S.); (R.B.)
| | - Luca Santini
- Department of Cardiology, Ospedale GB Grassi, 00121 Ostia, Italy;
| | | | - Massimo Grimaldi
- Department of Cardiology, Ospedale Generale Regionale F. Miulli, Acquaviva delle Fonti, 70021 Bari, Italy;
| | - Roberto Badagliacca
- Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, “Sapienza” University of Rome, Policlinico Umberto I, 00161 Rome, Italy; (M.M.); (M.S.); (R.B.)
| | - Luigi Lanata
- Medical Affairs Department, Dompé Farmaceutici SpA, 20057 Milan, Italy;
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10
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Li H, Fang J, Wei X, Xu D, Zhang T, Xiang Y, Chen HJ, Liu F, Xie X, Wang P, Hu N. Specific recognition of ion channel blocker by high-content cardiomyocyte electromechanical integrated correlation. Biosens Bioelectron 2020; 162:112273. [DOI: 10.1016/j.bios.2020.112273] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/29/2020] [Accepted: 05/02/2020] [Indexed: 12/22/2022]
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11
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Kodirov SA, Zhuravlev VL, Brachmann J. Prevailing Effects of Ibutilide on Fast Delayed Rectifier K + Channel. J Membr Biol 2019; 252:609-616. [PMID: 31584122 DOI: 10.1007/s00232-019-00098-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 07/29/2019] [Indexed: 11/27/2022]
Abstract
Effects of ibutilide, a class III antiarrhythmic drug, on delayed rectifier potassium currents (IK) in freshly isolated guinea pig ventricular myocytes were studied. Experiments were performed using the whole-cell configuration of patch-clamp technique under blockade of L-type calcium currents (Cav1). Ibutilide at concentrations ranging between 10 nM and 100 µM inhibited IKr in dose-dependent manner with a half maximal effective concentration of 2.03 ± 0.74 µM (n = 5-10). The amplitude of tail currents activated by prepulse to + 20 mV was decreased from 253 ± 52 to 130 ± 25 pA (n = 8, p < 0.01) in the presence of 1 µM ibutilide. The envelope test revealed time-dependent changes in ratio of IK-tail/ΔIK during 0.2-2 s pulse durations in the absence of drug. With ibutilide, regardless of pulse duration, a relatively constant ratio was estimated, indicative of predominant involvement of IKr component. The slow IKs persisted to greater extent even at 100 μM ibutilide revealing a distinguishable selectivity toward the IKr component.
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Affiliation(s)
- Sodikdjon A Kodirov
- Department of Cardiology, University Hospital Heidelberg, 69120, Heidelberg, Germany. .,Department of Physiology, Saint Petersburg University, Saint Petersburg, Russia, 199034. .,Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St., 02-093, Warsaw, Poland. .,Department of Cardiology, Klinikum Coburg, Teaching Hospital of the University of Würzburg, Coburg, Germany.
| | - Vladimir L Zhuravlev
- Department of Cardiology, University Hospital Heidelberg, 69120, Heidelberg, Germany.,Department of Physiology, Saint Petersburg University, Saint Petersburg, Russia, 199034
| | - Johannes Brachmann
- Department of Cardiology, University Hospital Heidelberg, 69120, Heidelberg, Germany.,Department of Cardiology, Klinikum Coburg, Teaching Hospital of the University of Würzburg, Coburg, Germany
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Thuma JB, Hooper SL. Choline and NMDG directly reduce outward currents: reduced outward current when these substances replace Na + is alone not evidence of Na +-activated K + currents. J Neurophysiol 2018; 120:3217-3233. [PMID: 30354793 DOI: 10.1152/jn.00871.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Choline chloride is often, and N-methyl-d-glucamine (NMDG) sometimes, used to replace sodium chloride in studies of sodium-activated potassium channels. Given the high concentrations used in sodium replacement protocols, it is essential to test that it is not the replacement substances themselves, as opposed to the lack of sodium, that cause any observed effects. We therefore compared, in lobster stomatogastric neurons and leech Retzius cells, the effects of applying salines in which choline chloride replaced sodium chloride, and in which choline hydroxide or sucrose was added to normal saline. We also tested, in stomatogastric neurons, the effect of adding NMDG to normal saline. These protocols allowed us to measure the direct effects (i.e., effects not due to changes in sodium concentration or saline osmolarity or ionic strength) of choline on stomatogastric and leech currents, and of NMDG on stomatogastric currents. Choline directly reduced transient and sustained depolarization-activated outward currents in both species, and NMDG directly reduced transient depolarization-activated outward currents in stomatogastric neurons. Experiments with lower choline concentrations showed that adding as little as 150 mM (stomatogastric) or 5 mM (leech) choline reduced at least some depolarization-activated outward currents. Reductions in outward current with choline chloride or NMDG replacement alone are thus not evidence of sodium-activated potassium currents. NEW & NOTEWORTHY We show that choline or N-methyl-d-glucamine (NMDG) directly (i.e., not due to changes in extracellular sodium) decrease outward currents. Prior work studying sodium-activated potassium channels in which sodium was replaced with choline or NMDG without an addition control may therefore be artifactual.
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Affiliation(s)
- Jeffrey B Thuma
- Department of Biological Sciences, Irvine Hall, Ohio University , Athens, Ohio
| | - Scott L Hooper
- Department of Biological Sciences, Irvine Hall, Ohio University , Athens, Ohio
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13
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Hu N, Wang T, Wan H, Zhuang L, Kettenhofen R, Zhang X, Zhang YS, Xu W, Gossmann M, Bohlen H, Hou X, Wang P. Synchronized electromechanical integration recording of cardiomyocytes. Biosens Bioelectron 2018; 117:354-365. [DOI: 10.1016/j.bios.2018.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/27/2018] [Accepted: 06/06/2018] [Indexed: 10/14/2022]
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14
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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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15
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Mizusawa Y, Morita H, Adler A, Havakuk O, Thollet A, Maury P, Wang DW, Hong K, Gandjbakhch E, Sacher F, Hu D, Amin AS, Lahrouchi N, Tan HL, Antzelevitch C, Probst V, Viskin S, Wilde AA. Prognostic significance of fever-induced Brugada syndrome. Heart Rhythm 2016; 13:1515-20. [DOI: 10.1016/j.hrthm.2016.03.044] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Indexed: 11/15/2022]
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Bannister ML, Alvarez-Laviada A, Thomas NL, Mason SA, Coleman S, du Plessis CL, Moran AT, Neill-Hall D, Osman H, Bagley MC, MacLeod KT, George CH, Williams AJ. Effect of flecainide derivatives on sarcoplasmic reticulum calcium release suggests a lack of direct action on the cardiac ryanodine receptor. Br J Pharmacol 2016; 173:2446-59. [PMID: 27237957 PMCID: PMC4945764 DOI: 10.1111/bph.13521] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/16/2016] [Accepted: 05/17/2016] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Flecainide is a use-dependent blocker of cardiac Na(+) channels. Mechanistic analysis of this block showed that the cationic form of flecainide enters the cytosolic vestibule of the open Na(+) channel. Flecainide is also effective in the treatment of catecholaminergic polymorphic ventricular tachycardia but, in this condition, its mechanism of action is contentious. We investigated how flecainide derivatives influence Ca(2) (+) -release from the sarcoplasmic reticulum through the ryanodine receptor channel (RyR2) and whether this correlates with their effectiveness as blockers of Na(+) and/or RyR2 channels. EXPERIMENTAL APPROACH We compared the ability of fully charged (QX-FL) and neutral (NU-FL) derivatives of flecainide to block individual recombinant human RyR2 channels incorporated into planar phospholipid bilayers, and their effects on the properties of Ca(2) (+) sparks in intact adult rat cardiac myocytes. KEY RESULTS Both QX-FL and NU-FL were partial blockers of the non-physiological cytosolic to luminal flux of cations through RyR2 channels but were significantly less effective than flecainide. None of the compounds influenced the physiologically relevant luminal to cytosol cation flux through RyR2 channels. Intracellular flecainide or QX-FL, but not NU-FL, reduced Ca(2) (+) spark frequency. CONCLUSIONS AND IMPLICATIONS Given its inability to block physiologically relevant cation flux through RyR2 channels, and its lack of efficacy in blocking the cytosolic-to-luminal current, the effect of QX-FL on Ca(2) (+) sparks is likely, by analogy with flecainide, to result from Na(+) channel block. Our data reveal important differences in the interaction of flecainide with sites in the cytosolic vestibules of Na(+) and RyR2 channels.
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Affiliation(s)
- Mark L Bannister
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Anita Alvarez-Laviada
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, UK
| | - N Lowri Thomas
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Sammy A Mason
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Sharon Coleman
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Christo L du Plessis
- Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, UK
| | - Abbygail T Moran
- Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, UK
| | - David Neill-Hall
- Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, UK
| | - Hasnah Osman
- School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - Mark C Bagley
- Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, UK
| | - Kenneth T MacLeod
- Myocardial Function Section, National Heart and Lung Institute, Imperial College London, London, UK
| | - Christopher H George
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Alan J Williams
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff, UK
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Osadchii OE. Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart. SCAND CARDIOVASC J 2015; 50:28-35. [DOI: 10.3109/14017431.2015.1099721] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Oleg E. Osadchii
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
- Department of Health Science and Technology, University of Aalborg, Aalborg, Denmark
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Melgari D, Zhang Y, El Harchi A, Dempsey CE, Hancox JC. Molecular basis of hERG potassium channel blockade by the class Ic antiarrhythmic flecainide. J Mol Cell Cardiol 2015; 86:42-53. [PMID: 26159617 PMCID: PMC4564290 DOI: 10.1016/j.yjmcc.2015.06.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/19/2015] [Accepted: 06/30/2015] [Indexed: 11/02/2022]
Abstract
The class Ic antiarrhythmic drug flecainide inhibits KCNH2-encoded "hERG" potassium channels at clinically relevant concentrations. The aim of this study was to elucidate the underlying molecular basis of this action. Patch clamp recordings of hERG current (IhERG) were made from hERG expressing cells at 37°C. Wild-type (WT) IhERG was inhibited with an IC50 of 1.49μM and this was not significantly altered by reversing the direction of K(+) flux or raising external [K(+)]. The use of charged and uncharged flecainide analogues showed that the charged form of the drug accesses the channel from the cell interior to produce block. Promotion of WT IhERG inactivation slowed recovery from inhibition, whilst the N588K and S631A attenuated-inactivation mutants exhibited IC50 values 4-5 fold that of WT IhERG. The use of pore-helix/selectivity filter (T623A, S624A V625A) and S6 helix (G648A, Y652A, F656A) mutations showed <10-fold shifts in IC50 for all but V625A and F656A, which respectively exhibited IC50s 27-fold and 142-fold their WT controls. Docking simulations using a MthK-based homology model suggested an allosteric effect of V625A, since in low energy conformations flecainide lay too low in the pore to interact directly with that residue. On the other hand, the molecule could readily form π-π stacking interactions with aromatic residues and particularly with F656. We conclude that flecainide accesses the hERG channel from the cell interior on channel gating, binding low in the inner cavity, with the S6 F656 residue acting as a principal binding determinant.
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Affiliation(s)
- Dario Melgari
- School of Physiology & Pharmacology, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Yihong Zhang
- School of Physiology & Pharmacology, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Aziza El Harchi
- School of Physiology & Pharmacology, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Christopher E Dempsey
- School of Biochemistry, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Jules C Hancox
- School of Physiology & Pharmacology, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.
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Salvage SC, King JH, Chandrasekharan KH, Jafferji DIG, Guzadhur L, Matthews HR, Huang CL, Fraser JA. Flecainide exerts paradoxical effects on sodium currents and atrial arrhythmia in murine RyR2-P2328S hearts. Acta Physiol (Oxf) 2015; 214:361-75. [PMID: 25850710 PMCID: PMC4510817 DOI: 10.1111/apha.12505] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/03/2014] [Accepted: 04/01/2015] [Indexed: 12/30/2022]
Abstract
Aims Cardiac ryanodine receptor mutations are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), and some, including RyR2-P2328S, also predispose to atrial fibrillation. Recent work associates reduced atrial Nav1.5 currents in homozygous RyR2-P2328S (RyR2S/S) mice with slowed conduction and increased arrhythmogenicity. Yet clinically, and in murine models, the Nav1.5 blocker flecainide reduces ventricular arrhythmogenicity in CPVT. We aimed to determine whether, and how, flecainide influences atrial arrhythmogenicity in RyR2S/S mice and their wild-type (WT) littermates. Methods We explored effects of 1 μm flecainide on WT and RyR2S/S atria. Arrhythmic incidence, action potential (AP) conduction velocity (CV), atrial effective refractory period (AERP) and AP wavelength (λ = CV × AERP) were measured using multi-electrode array recordings in Langendorff-perfused hearts; Na+ currents (INa) were recorded using loose patch clamping of superfused atria. Results RyR2S/S showed more frequent atrial arrhythmias, slower CV, reduced INa and unchanged AERP compared to WT. Flecainide was anti-arrhythmic in RyR2S/S but pro-arrhythmic in WT. It increased INa in RyR2S/S atria, whereas it reduced INa as expected in WT. It increased AERP while sparing CV in RyR2S/S, but reduced CV while sparing AERP in WT. Thus, RyR2S/S hearts have low λ relative to WT; flecainide then increases λ in RyR2S/S but decreases λ in WT. Conclusions Flecainide (1 μm) rescues the RyR2-P2328S atrial arrhythmogenic phenotype by restoring compromised INa and λ, changes recently attributed to increased sarcoplasmic reticular Ca2+ release. This contrasts with the increased arrhythmic incidence and reduced INa and λ with flecainide in WT.
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Affiliation(s)
- S. C. Salvage
- Physiological Laboratory University of Cambridge Cambridge UK
| | - J. H. King
- Physiological Laboratory University of Cambridge Cambridge UK
| | | | | | - L. Guzadhur
- Department of Biochemistry University of Cambridge Cambridge UK
| | - H. R. Matthews
- Physiological Laboratory University of Cambridge Cambridge UK
| | - C. L.‐H. Huang
- Physiological Laboratory University of Cambridge Cambridge UK
- Department of Biochemistry University of Cambridge Cambridge UK
| | - J. A. Fraser
- Physiological Laboratory University of Cambridge Cambridge UK
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Kirchhoff JE, Goldin Diness J, Sheykhzade M, Grunnet M, Jespersen T. Synergistic antiarrhythmic effect of combining inhibition of Ca2+-activated K+ (SK) channels and voltage-gated Na+ channels in an isolated heart model of atrial fibrillation. Heart Rhythm 2015; 12:409-18. [DOI: 10.1016/j.hrthm.2014.12.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Indexed: 11/28/2022]
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Abnormal sodium current properties contribute to cardiac electrical and contractile dysfunction in a mouse model of myotonic dystrophy type 1. Neuromuscul Disord 2014; 25:308-20. [PMID: 25613807 DOI: 10.1016/j.nmd.2014.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 11/14/2014] [Accepted: 11/24/2014] [Indexed: 11/21/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is the most common neuromuscular disorder and is associated with cardiac conduction defects. However, the mechanisms of cardiac arrhythmias in DM1 are unknown. We tested the hypothesis that abnormalities in the cardiac sodium current (INa) are involved, and used a transgenic mouse model reproducing the expression of triplet expansion observed in DM1 (DMSXL mouse). The injection of the class-I antiarrhythmic agent flecainide induced prominent conduction abnormalities and significantly lowered the radial tissular velocities and strain rate in DMSXL mice compared to WT. These abnormalities were more pronounced in 8-month-old mice than in 3-month-old mice. Ventricular action potentials recorded by standard glass microelectrode technique exhibited a lower maximum upstroke velocity [dV/dt](max) in DMSXL. This decreased [dV/dt](max) was associated with a 1.7 fold faster inactivation of INa in DMSXL myocytes measured by the whole-cell patch-clamp technique. Finally in the DMSXL mouse, no mutation in the Scn5a gene was detected and neither cardiac fibrosis nor abnormalities of expression of the sodium channel protein were observed. Therefore, alterations in the sodium current markedly contributed to electrical conduction block in DM1. This result should guide pharmaceutical and clinical research toward better therapy for the cardiac arrhythmias associated with DM1.
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Gibson JK, Yue Y, Bronson J, Palmer C, Numann R. Human stem cell-derived cardiomyocytes detect drug-mediated changes in action potentials and ion currents. J Pharmacol Toxicol Methods 2014; 70:255-67. [DOI: 10.1016/j.vascn.2014.09.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 09/02/2014] [Accepted: 09/04/2014] [Indexed: 10/24/2022]
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Rampe D, Brown AM. A history of the role of the hERG channel in cardiac risk assessment. J Pharmacol Toxicol Methods 2013; 68:13-22. [DOI: 10.1016/j.vascn.2013.03.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/14/2013] [Accepted: 03/14/2013] [Indexed: 01/25/2023]
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Apostolakis S, Oeff M, Tebbe U, Fabritz L, Breithardt G, Kirchhof P. Flecainide acetate for the treatment of atrial and ventricular arrhythmias. Expert Opin Pharmacother 2013; 14:347-57. [DOI: 10.1517/14656566.2013.759212] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Flecainide-Induced Proarrhythmia Is Attributed to Abnormal Changes in Repolarization and Refractoriness in Perfused Guinea-Pig Heart. J Cardiovasc Pharmacol 2012; 60:456-66. [DOI: 10.1097/fjc.0b013e31826b86cf] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Osadchii OE. Impact of Na+ channel blockers on transmural dispersion of refractoriness and arrhythmic susceptibility in guinea-pig left ventricle. Eur J Pharmacol 2012; 691:173-81. [DOI: 10.1016/j.ejphar.2012.07.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/27/2012] [Accepted: 07/02/2012] [Indexed: 02/03/2023]
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Abstract
Flecainide is a class Ic antiarrhythmic agent that has an important role as part of rhythm control strategies in patients with atrial fibrillation (AF). Early clinical data on the use of flecainide showed an increase in arrhythmias and mortality compared with placebo in patients with a previous myocardial infarction and asymptomatic or mildly symptomatic ventricular arrhythmias. These findings only apply to a specific group of patients with left ventricular dysfunction and ischaemic heart disease, but had a negative impact on the use of class Ic antiarrhythmics across all indications and patient groups. The aim of this review was to evaluate the available safety data for flecainide in the literature and to assess its current use in patients with AF. Current European guidelines now recommend the use of flecainide in carefully selected groups of patients with AF who do not have structural heart disease. This includes for the cardioversion of recent-onset AF, pretreatment prior to direct current cardioversion, out-of-hospital acute oral therapy ('pill-in-the-pocket' approach) and for the ongoing maintenance of sinus rhythm. Potential cardiac adverse effects of flecainide include proarrhythmia, conduction abnormalities and negative inotropic effects. Dizziness is the most frequent non-cardiac side effect, followed by blurred vision and difficulty focusing; these are almost all mild, transient and tolerable. Data from recent clinical trials in patients with supraventricular arrhythmias suggest that flecainide has a good tolerability profile in groups of appropriately selected patients. Caution is required when using flecainide in patients with renal dysfunction, and there are a number of drug interactions, but these are well documented and manageable. Overall, flecainide is a good choice for the pharmacological management of AF. It has a good safety record and low incidence of adverse effects, rare end-organ toxicity and a low risk of ventricular proarrhythmia. To ensure that the benefits of treatment outweigh any potential risks, careful patient selection and monitoring is required.
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Affiliation(s)
- Juan Tamargo
- Department of Pharmacology, School of Medicine, Universidad Complutense, Madrid, Spain.
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Osadchii OE. Effects of ventricular pacing protocol on electrical restitution assessments in guinea-pig heart. Exp Physiol 2012; 97:807-21. [DOI: 10.1113/expphysiol.2012.065219] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Aréchiga-Figueroa IA, Rodríguez-Martínez M, Sánchez-Chapula JA. Voltage-dependent potassium currents in feline sino-atrial node myocytes. Pflugers Arch 2011; 462:385-96. [DOI: 10.1007/s00424-011-0984-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/30/2011] [Accepted: 06/06/2011] [Indexed: 11/28/2022]
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Nerbonne JM. Molecular Analysis of Voltage‐Gated K
+
Channel Diversity and Functioning in the Mammalian Heart. Compr Physiol 2011. [DOI: 10.1002/cphy.cp020115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Aliot E, Capucci A, Crijns HJ, Goette A, Tamargo J. Twenty-five years in the making: flecainide is safe and effective for the management of atrial fibrillation. Europace 2010; 13:161-73. [PMID: 21138930 PMCID: PMC3024037 DOI: 10.1093/europace/euq382] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia in clinical practise and its prevalence is increasing. Over the last 25 years, flecainide has been used extensively worldwide, and its capacity to reduce AF symptoms and provide long-term restoration of sinus rhythm (SR) has been well documented. The increased mortality seen in patients treated with flecainide in the Cardiac Arrhythmia Suppression Trial (CAST) study, published in 1991, still deters many clinicians from using flecainide, denying many new AF patients a valuable treatment option. There is now a body of evidence that clearly demonstrates that flecainide has a favourable safety profile in AF patients without significant left ventricular disease or coronary heart disease. As a result of this evidence, flecainide is now recommended as one of the first-line treatment options for restoring and maintaining SR in patients with AF under current treatment guidelines. The objective of this article is to review the literature pertaining to the pharmacological characteristics, safety and efficacy of flecainide, and to place this drug in the context of current therapeutic management strategies for AF.
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Affiliation(s)
- Etienne Aliot
- Département de Cardiologie, CHU de Nancy, Hôpital de Brabois, rue du Morvan, 54511 Vandoeuvre-lès-Nancy Cedex, France.
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Indik JH, Woosley RL. Pharmacokinetics/Pharmacodynamics of Antiarrhythmic Drugs. Card Electrophysiol Clin 2010; 2:341-358. [PMID: 28770794 DOI: 10.1016/j.ccep.2010.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This article describes the pharmacology of antiarrhythmic medications. Although these medications are broadly considered in terms of their blockade of either sodium or potassium channels, they act by a variety of pharmacodynamic mechanisms. Elimination may be via hepatic metabolism or renal mechanisms, or a combination. In particular, interactions between antiarrhythmic medications and other drugs that interfere with hepatic metabolism by P450 enzymes is a source for toxicity.
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Affiliation(s)
- Julia H Indik
- Department of Medicine, Sarver Heart Center, University of Arizona College of Medicine, 1501 North Campbell Avenue, Tucson, AZ 85724-5037, USA
| | - Raymond L Woosley
- Department of Medicine, Sarver Heart Center, University of Arizona College of Medicine, 1501 North Campbell Avenue, Tucson, AZ 85724-5037, USA; The Critical Path Institute, 1730 East River Road, #200, Tucson, AZ 85718, USA
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Flecainide increases Kir2.1 currents by interacting with cysteine 311, decreasing the polyamine-induced rectification. Proc Natl Acad Sci U S A 2010; 107:15631-6. [PMID: 20713726 DOI: 10.1073/pnas.1004021107] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Both increase and decrease of cardiac inward rectifier current (I(K1)) are associated with severe cardiac arrhythmias. Flecainide, a widely used antiarrhythmic drug, exhibits ventricular proarrhythmic effects while effectively controlling ventricular arrhythmias associated with mutations in the gene encoding Kir2.1 channels that decrease I(K1) (Andersen syndrome). Here we characterize the electrophysiological and molecular basis of the flecainide-induced increase of the current generated by Kir2.1 channels (I(Kir2.1)) and I(K1) recorded in ventricular myocytes. Flecainide increases outward I(Kir2.1) generated by homotetrameric Kir2.1 channels by decreasing their affinity for intracellular polyamines, which reduces the inward rectification of the current. Flecainide interacts with the HI loop of the cytoplasmic domain of the channel, Cys311 being critical for the effect. This explains why flecainide does not increase I(Kir2.2) and I(Kir2.3), because Kir2.2 and Kir2.3 channels do not exhibit a Cys residue at the equivalent position. We further show that incubation with flecainide increases expression of functional Kir2.1 channels in the membrane, an effect also determined by Cys311. Indeed, flecainide pharmacologically rescues R67W, but not R218W, channel mutations found in Andersen syndrome patients. Moreover, our findings provide noteworthy clues about the structural determinants of the C terminus cytoplasmic domain of Kir2.1 channels involved in the control of gating and rectification.
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Voigt N, Rozmaritsa N, Trausch A, Zimniak T, Christ T, Wettwer E, Matschke K, Dobrev D, Ravens U. Inhibition of IK,ACh current may contribute to clinical efficacy of class I and class III antiarrhythmic drugs in patients with atrial fibrillation. Naunyn Schmiedebergs Arch Pharmacol 2009; 381:251-9. [PMID: 19760273 DOI: 10.1007/s00210-009-0452-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 08/28/2009] [Indexed: 12/19/2022]
Abstract
Inward rectifier potassium currents I(K1) and acetylcholine activated I(K,ACh) are implicated in atrial fibrillation (AF) pathophysiology. In chronic AF (cAF), I(K,ACh) develops a receptor-independent, constitutively active component that together with increased I(K1) is considered to support maintenance of AF. Here, we tested whether class I (propafenone, flecainide) and class III (dofetilide, AVE0118) antiarrhythmic drugs inhibit atrial I(K1) and I(K,ACh) in patients with and without cAF. I(K1) and I(K,ACh) were measured with voltage clamp technique in atrial myocytes from 58 sinus rhythm (SR) and 35 cAF patients. The M-receptor agonist carbachol (CCh; 2 microM) was employed to activate I(K,ACh). In SR, basal current was not affected by either drug indicating no effect of these compounds on I(K1). In contrast, all tested drugs inhibited CCh-activated I(K,ACh) in a concentration-dependent manner. In cAF, basal current was confirmed to be larger than in SR (at -80 mV, -15.2 +/- 1.2 pA/pF, n = 88/35 vs. -6.5 +/- 0.4 pA/pF, n = 194/58 [myocytes/patients]; P < 0.05), whereas CCh-activated I(K,ACh) was smaller (-4.1 +/- 0.5 pA/pF vs. -9.5 +/- 0.6 pA/pF; P < 0.05). In cAF, receptor-independent constitutive I(K,ACh) contributes to increased basal current, which was reduced by flecainide and AVE0118 only. This may be due to inhibition of constitutively active I(K,ACh) channels. In cAF, all tested drugs reduced CCh-activated I(K,ACh). We conclude that in cAF, flecainide and AVE0118 reduce receptor-independent, constitutively active I(K,ACh), suggesting that they may block I(K,ACh) channels, whereas propafenone and dofetilide likely inhibit M-receptors. The efficacy of flecainide to terminate AF may in part result from blockade of I(K,ACh).
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Affiliation(s)
- Niels Voigt
- Department of Pharmacology and Toxicology, Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
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Killeen MJ. Drug-induced arrhythmias and sudden cardiac death: implications for the pharmaceutical industry. Drug Discov Today 2009; 14:589-97. [PMID: 19508921 DOI: 10.1016/j.drudis.2009.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 03/01/2009] [Accepted: 03/02/2009] [Indexed: 01/23/2023]
Abstract
Following a series of high profile withdrawals from the market, the ability of medications to induce potentially fatal arrhythmias is a significant problem facing the pharmaceutical industry. Current preclinical cardiac safety assays are based on the assumption that blockade of a single repolarizing K(+) channel alone precipitates drug-induced arrhythmias, however, current findings point to a range of more complex arrhythmogenic mechanisms. This review begins by exploring clinical findings and potential mechanisms underlying drug-induced sudden cardiac death and then goes on to assess current and explore future strategies to detect cardiotoxicity at the preclinical stage.
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Himmel HM. Mechanisms Involved in Cardiac Sensitization by Volatile Anesthetics: General Applicability to Halogenated Hydrocarbons? Crit Rev Toxicol 2008; 38:773-803. [DOI: 10.1080/10408440802237664] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Wang X, Xu R, Abernathey G, Taylor J, Alzghoul M, Hannon K, Hockerman GH, Pond AL. Kv11.1 channel subunit composition includes minK and varies developmentally in mouse cardiac muscle. Dev Dyn 2008; 237:2430-7. [DOI: 10.1002/dvdy.21671] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Different Effects of Antiarrhythmic Drugs on the Rate-Dependency of QT Interval: A Study With Amiodarone and Flecainide. J Cardiovasc Pharmacol 2007; 50:535-40. [DOI: 10.1097/fjc.0b013e3181451473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Clements-Jewery H, Kanaganayagam GS, Kabra R, Curtis MJ. Actions of flecainide on susceptibility to phase-2 ventricular arrhythmias during infarct evolution in rat isolated perfused hearts. Br J Pharmacol 2006; 147:468-75. [PMID: 16415912 PMCID: PMC1616984 DOI: 10.1038/sj.bjp.0706633] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The mechanism of flecainide-induced unexpected death remains uncertain. Phase-2 ventricular arrhythmias occur during infarct evolution. We examined whether flecainide (0.74 and 1.48 microM, representing the peak unbound plasma and total blood concentrations, respectively, at 'therapeutic' dosage) has proarrhythmic activity on phase-2 arrhythmia susceptibility during infarct evolution. To achieve this, we used the Langendorff-perfused rat heart preparation (n=8 per group) in which baseline phase-2 arrhythmia susceptibility is low. Left main coronary occlusion evoked phase-1 (acute ischaemia-induced) ventricular arrhythmias including fibrillation (VF) in all hearts. By 90 min, hearts were relatively arrhythmia-free. Randomized and blinded switch of perfusion to flecainide at 90 min caused no increase over baseline in the incidence of VF, tachycardia (VT) or premature beats (VPB) during the following 150 min of ischaemia, or during reperfusion (begun 240 min after the onset of ischaemia). In separate hearts, catecholamines (313 nM norepinephrine and 75 nM epinephrine) were co-perfused with flecainide from 90 min of ischaemia. Catecholamine perfusion increased heart rate, coronary flow and QT interval, and shortened PR interval (all P<0.05), actions that were not altered by flecainide. Catecholamine perfusion caused a weak nonsignificant increase in phase-2 VPB, VT and VF incidence, but there was no proarrhythmic interaction with flecainide. In conclusion, the present findings suggest that the increased risk of death associated with clinical use of flecainide is not due to facilitation of phase-2 ventricular arrhythmias.
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Affiliation(s)
- Hugh Clements-Jewery
- Cardiovascular Division, Kings College London, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH
| | | | - Ruchi Kabra
- Cardiovascular Division, Kings College London, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH
| | - Michael J Curtis
- Cardiovascular Division, Kings College London, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH
- Author for correspondence:
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Wehrens XHT. Structural determinants of potassium channel blockade and drug-induced arrhythmias. Handb Exp Pharmacol 2006:123-57. [PMID: 16610343 DOI: 10.1007/3-540-29715-4_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cardiac K+ channels play an important role in the regulation of the shape and duration of the action potential. They have been recognized as targets for the actions of neurotransmitters, hormones, and anti-arrhythmic drugs that prolong the action potential duration (APD) and increase refractoriness. However, pharmacological therapy, often for the purpose of treating syndromes unrelated to cardiac disease, can also increase the vul- nerability of some patients to life-threatening rhythm disturbances. This may be due to an underlying propensity stemming from inherited mutations or polymorphisms, or structural abnormalities that provide a substrate allowing for the initiation of arrhythmic triggers. A number of pharmacological agents that have proved useful in the treatment of allergic reactions, gastrointestinal disorders, and psychotic disorders, among others, have been shown to reduce repolarizing K+ currents and prolong the Q-T interval on the electrocardiogram. Understanding the structural determinants of K+ channel blockade might provide new insights into the mechanism and rate-dependent effects of drugs on cellular physiology. Drug-induced disruption of cellular repolarization underlies electrocardiographic abnormalities that are diagnostic indicators of arrhythmia susceptibility.
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Affiliation(s)
- X H T Wehrens
- Center for Molecular Cardiology, Dept. of Physiology and Cellular Biophysics, College of Physicians and Surgeons of Columbia University, 630 West 168th Street, P&S 9-401, New York, NY 10032, USA.
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Abstract
The heart is a rhythmic electromechanical pump, the functioning of which depends on action potential generation and propagation, followed by relaxation and a period of refractoriness until the next impulse is generated. Myocardial action potentials reflect the sequential activation and inactivation of inward (Na(+) and Ca(2+)) and outward (K(+)) current carrying ion channels. In different regions of the heart, action potential waveforms are distinct, owing to differences in Na(+), Ca(2+), and K(+) channel expression, and these differences contribute to the normal, unidirectional propagation of activity and to the generation of normal cardiac rhythms. Changes in channel functioning, resulting from inherited or acquired disease, affect action potential repolarization and can lead to the generation of life-threatening arrhythmias. There is, therefore, considerable interest in understanding the mechanisms that control cardiac repolarization and rhythm generation. Electrophysiological studies have detailed the properties of the Na(+), Ca(2+), and K(+) currents that generate cardiac action potentials, and molecular cloning has revealed a large number of pore forming (alpha) and accessory (beta, delta, and gamma) subunits thought to contribute to the formation of these channels. Considerable progress has been made in defining the functional roles of the various channels and in identifying the alpha-subunits encoding these channels. Much less is known, however, about the functioning of channel accessory subunits and/or posttranslational processing of the channel proteins. It has also become clear that cardiac ion channels function as components of macromolecular complexes, comprising the alpha-subunits, one or more accessory subunit, and a variety of other regulatory proteins. In addition, these macromolecular channel protein complexes appear to interact with the actin cytoskeleton and/or the extracellular matrix, suggesting important functional links between channel complexes, as well as between cardiac structure and electrical functioning. Important areas of future research will be the identification of (all of) the molecular components of functional cardiac ion channels and delineation of the molecular mechanisms involved in regulating the expression and the functioning of these channels in the normal and the diseased myocardium.
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Affiliation(s)
- Jeanne M Nerbonne
- Dept. of Molecular Biology and Pharmacology, Washington University Medical School, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Suto F, Zhu W, Cahill SA, Greenwald I, Navarro ALC, Gross GJ. Ventricular rate determines early bradycardic electrical remodeling. Heart Rhythm 2005; 2:293-300. [PMID: 15851321 DOI: 10.1016/j.hrthm.2004.12.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 12/14/2004] [Indexed: 11/19/2022]
Abstract
OBJECTIVES The purpose of this study was to isolate chronic ventricular rate as the primary determinant of early bradycardic ventricular electrical remodeling. BACKGROUND Ventricular repolarization delay predisposing to potentially lethal tachydysrhythmias occurs during chronic bradycardia. Prolonged QT intervals and torsades de pointes are associated with down-regulated ventricular myocyte delayed rectifier potassium (K(+)) currents. METHODS Transcatheter AV node ablation in rabbits was followed by chronic right ventricular pacing at either 140 bpm (n = 16) or the near-physiologic rate of 280 bpm (n = 9). ECG QT intervals were assessed in vivo at days 0 and 8 of paced AV block. Repolarizing currents in isolated left and right ventricular myocytes were assessed using whole-cell patch clamp technique. RESULTS Bradycardic rabbits had increased steady-state QT intervals (230 +/- 6 ms vs 206 +/- 7 ms [mean +/- SE], day 8 vs day 0; P < .001). Biventricular myocyte expression of the delayed rectifier K(+) currents I(Kr) and I(Ks) was down-regulated in bradycardic rabbits, with no change in the transient outward current I(to) or inwardly rectifying current I(K1). None of these changes were observed in rabbits paced at 280 bpm. Pause-dependent torsades de pointes was documented in one bradycardic animal on day 8. No heart failure or ventricular hypertrophy was apparent. CONCLUSIONS Bradycardic ventricular electrical remodeling proceeds independently of structural remodeling, heart failure, or AV synchrony and is prevented by maintenance of near-physiologic ventricular rate.
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Affiliation(s)
- Fumiaki Suto
- Cardiovascular Research Programme, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
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Aiba T, Shimizu W, Inagaki M, Noda T, Miyoshi S, Ding WG, Zankov DP, Toyoda F, Matsuura H, Horie M, Sunagawa K. Cellular and ionic mechanism for drug-induced long QT syndrome and effectiveness of verapamil. J Am Coll Cardiol 2005; 45:300-7. [PMID: 15653031 DOI: 10.1016/j.jacc.2004.09.069] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Accepted: 09/28/2004] [Indexed: 11/17/2022]
Abstract
OBJECTIVES We examined the cellular and ionic mechanism for QT prolongation and subsequent Torsade de Pointes (TdP) and the effect of verapamil under conditions mimicking KCNQ1 (I(Ks) gene) defect linked to acquired long QT syndrome (LQTS). BACKGROUND Agents with an I(Kr)-blocking effect often induce marked QT prolongation in patients with acquired LQTS. Previous reports demonstrated a relationship between subclinical mutations in cardiac K+ channel genes and a risk of drug-induced TdP. METHODS Transmembrane action potentials from epicardial (EPI), midmyocardial (M), and endocardial (ENDO) cells were simultaneously recorded, together with a transmural electrocardiogram, at a basic cycle length of 2,000 ms in arterially perfused feline left ventricular preparations. RESULTS The I(Kr) block (E-4031: 1 micromol/l) under control conditions (n = 5) prolonged the QT interval but neither increased transmural dispersion of repolarization (TDR) nor induced arrhythmias. However, the I(Kr) blocker under conditions with I(Ks) suppression by chromanol 293B 10 micromol/l mimicking the KCNQ1 defect (n = 10) preferentially prolonged action potential duration (APD) in EPI rather than M or ENDO, thereby dramatically increasing the QT interval and TDR. Spontaneous or epinephrine-induced early afterdepolarizations (EADs) were observed in EPI, and subsequent TdP occurred only under both I(Ks) and I(Kr) suppression. Verapamil (0.1 to 5.0 micromol/l) dose-dependently abbreviated APD in EPI more than in M and ENDO, thereby significantly decreasing the QT interval, TDR, and suppressing EADs and TdP. CONCLUSIONS Subclinical I(Ks) dysfunction could be a risk of drug-induced TdP. Verapamil is effective in decreasing the QT interval and TDR and in suppressing EADs, thus preventing TdP in the model of acquired LQTS.
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Affiliation(s)
- Takeshi Aiba
- Department of Cardiovascular Dynamics, Research Institute, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan
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Cahill SA, Gross GJ. Propafenone and Its Metabolites Preferentially Inhibit IKrin Rabbit Ventricular Myocytes. J Pharmacol Exp Ther 2003; 308:59-65. [PMID: 14569067 DOI: 10.1124/jpet.103.057844] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Propafenone is an antiarrhythmic agent with recognized cardiac myocyte repolarizing K+ current inhibitory effects. It has two known electropharmacologically active metabolites, 5-hydroxy- and N-depropylpropafenone, whose K+ current inhibitory effects are less thoroughly elucidated than those of the parent compound. This study characterizes and directly compares the pharmacologic interaction of all three compounds with two key repolarizing K+ currents, the rapidly activating delayed rectifier IKr and the transient outward current Ito, using the whole-cell patch-clamp technique in isolated rabbit ventricular myocytes. All three agents potently inhibited IKr with IC50 values of 0.80 +/-0.14, 1.88 +/-0.21, and 5.78 +/-1.24 microM for propafenone, 5-hydroxypropafenone, and N-depropylpropafenone, respectively, based on reduction of peak tail current amplitude following repolarization from +50 mV to -30 mV. IKr inhibition was concentration- and weakly voltage-dependent, with a time course from channel activation that was well described by a single exponential model and consistent with open channel block. Propafenone and its 5-hydroxy and N-depropyl metabolites also blocked Ito with IC50 values of 7.27 +/-0.53, 40.29 +/-7.55, and 44.26 +/-5.73 microM, respectively, at +50 mV. No significant drug effects were observed with respect to Ito voltage dependence of steady-state inactivation or time course of recovery from inactivation. The preferential interaction of propafenone and its metabolites with IKr relative to Ito in ventricular myocytes sheds new light on the anti- and proarrhythmic activity of propafenone in vivo.
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Affiliation(s)
- Sean A Cahill
- Department of Pediatrics and Child Health, University of Manitoba, Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Center, Winnipeg, Canada
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Clancy CE, Kurokawa J, Tateyama M, Wehrens XHT, Kass RS. K+ channel structure-activity relationships and mechanisms of drug-induced QT prolongation. Annu Rev Pharmacol Toxicol 2003; 43:441-61. [PMID: 12540747 DOI: 10.1146/annurev.pharmtox.43.100901.140245] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pharmacological intervention, often for the purpose of treating syndromes unrelated to cardiac disease, can increase the vulnerability of some patients to life-threatening rhythm disturbances. This may be due to an underlying propensity stemming from genetic defects or polymorphisms, or structural abnormalities that provide a substrate allowing for the initiation of arrhythmic triggers. A number of pharmacological agents that have proven useful in the treatment of allergic reactions, gastrointestinal disorders, and psychotic disorders, among others, have been shown to reduce repolarizing K(+) currents and prolong the QT interval on the electrocardiogram. Understanding the structural determinants of K(+) channel blockade may provide new insights into the mechanism and rate-dependent effects of drugs on cellular physiology. Drug-induced disruption of cellular repolarization underlies electrocardiographic abnormalities that are diagnostic indicators of arrhythmia susceptibility.
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Affiliation(s)
- Colleen E Clancy
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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47
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Finley MR, Lillich JD, Gilmour RF, Freeman LC. Structural and functional basis for the long QT syndrome: relevance to veterinary patients. J Vet Intern Med 2003; 17:473-88. [PMID: 12892298 DOI: 10.1111/j.1939-1676.2003.tb02468.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Long QT syndrome (LQTS) is a condition characterized by prolongation of ventricular repolarization and is manifested clinically by lengthening of the QT interval on the surface ECG. Whereas inherited forms of LQTS associated with mutations in the genes that encode ion channel proteins are identified only in humans, the acquired form of LQTS occurs in humans and companion animal species. Often, acquired LQTS is associated with drug-induced block of the cardiac K+ current designated I(Kr). However, not all drugs that induce potentially fatal ventricular arrhythmias antagonize I(Kr), and not all drugs that block I(Kr), are associated with ventricular arrhythmias. In clinical practice, the extent of QT interval prolongation and risk of ventricular arrhythmia associated with antagonism of I(Kr) are modulated by pharmacokinetic and pharmacodynamic variables. Veterinarians can influence some of the potential risk factors (eg, drug dosage, route of drug administration, presence or absence of concurrent drug therapy, and patient electrolyte status) but not all (eg, patient gender/genetic background). Veterinarians need to be aware of the potential for acquired LQTS during therapy with drugs identified as blockers of HERG channels and I(Kr).
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Affiliation(s)
- Melissa R Finley
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5802, USA
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Amitzur G, Shenkar N, Leor J, Novikov I, Eldar M. Modulation of ventricular fibrillation in isolated perfused heart by dofetilide. J Cardiovasc Pharmacol 2003; 41:838-48. [PMID: 12775960 DOI: 10.1097/00005344-200306000-00003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The authors studied the involvement of IKr potassium current in ventricular fibrillation during perfusion. Electrophysiologic parameters were measured before and after dofetilide administration (2.5, 7.5, and 12.5 x 10-7 M, n = 8) in isolated perfused feline hearts. During pacing, these parameters included epicardial conduction time, refractoriness, and the fastest rate for 1:1 pacing/response capture. During 8 minutes of electrically induced tachyarrhythmias, they included heart rate and normalized entropy reflecting the degree of organization. In all groups, arrhythmia rate was slower in the right ventricle than in the left ventricle. Dofetilide decreased the arrhythmia rate more than it increased organization, reduced its maintenance, or increased difficulty in initiation. Refractoriness was prolonged in a reverse use-dependent way which was less than 1:1 pacing/response capture. Unexpectedly, a moderate prolongation of conduction time was observed. Inverse correlation was found between the arrhythmia rate and changes in refractoriness and conduction time and between the degree of organization and refractoriness (both ventricles) and conduction time (right ventricle). Dofetilide, which intensively blocks IKr current and unexpectedly suppressed conduction, has different quantitative effects on fibrillation features. These changes in fibrillation suggest that these effects are mainly associated with refractoriness prolongation and do not seem to be attenuated by conduction suppression.
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Affiliation(s)
- Giora Amitzur
- Neufeld Cardiac Research Institute, Sheba Medical Center, Tel Hashomer 52621, Israel.
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Aiba T, Shimizu W, Inagaki M, Hidaka I, Tatewaki T, Sunagawa K. Transmural heterogeneity of the action potential configuration in the feline left ventricle. Circ J 2003; 67:449-54. [PMID: 12736486 DOI: 10.1253/circj.67.449] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There are M cells in the canine, rabbit, guinea pig, and human left ventricle (LV), but it is not known if they are present in the feline LV. Arterially perfused feline LV preparations were used for the recording of transmembrane action potentials from the epicardium (Epi), midmyocardium (M) and endomyocardium (Endo) under control conditions (n=12) and in the presence of I(Ks) blocker (chromanol 293B: 10 micromol/L, n=6) or I(Kr) blocker (E-4031: 2 micromol/L, n=6). The steady-state action potential duration at 90% repolarization and cycle length (APD90/CL) relation was obtained and fitted by the hyperbolic function APD(90) = CL/[(a x CL) + b]. In control, the shortest and longest action potential duration (APD) were observed in Epi and M, respectively, and the APD(90)/CL-relation curve was steeper in the M or Endo than in the Epi. Chromanol 293B prolonged APD in Epi, but not in M or Endo, resulting in no significant difference of the APD(90)/CL-relation curve among the 3 regions. E-4031 markedly, but homogeneously, prolonged APD in all regions, giving rise to decreased transmural dispersion of repolarization. In conclusion, there exists an M cell layer with a longer APD than the Epi and Endo layers and there is transmural electrical heterogeneity in the feline LV; however, the response to I(Kr) blocker is different from that of the canine LV probably because of species differences in the I(Kr) and I(Ks).
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Affiliation(s)
- Takeshi Aiba
- Department of Cardiovascular Dynamics, Research Institute, National Cardiovascular Center, Suita, Japan
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50
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Physiology and Molecular Biology of Ion Channels Contributing to Ventricular Repolarization. CONTEMPORARY CARDIOLOGY 2003. [DOI: 10.1007/978-1-59259-362-0_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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