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Winbo A, Ramanan S, Eugster E, Rydberg A, Jovinge S, Skinner JR, Montgomery JM. Functional hyperactivity in long QT syndrome type 1 pluripotent stem cell-derived sympathetic neurons. Am J Physiol Heart Circ Physiol 2021; 321:H217-H227. [PMID: 34142889 DOI: 10.1152/ajpheart.01002.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic activation is an established trigger of life-threatening cardiac events in long QT syndrome type 1 (LQT1). KCNQ1 loss-of-function variants, which underlie LQT1, have been associated with both cardiac arrhythmia and neuronal hyperactivity pathologies. However, the LQT1 sympathetic neuronal phenotype is unknown. Here, we aimed to study human induced pluripotent stem cell (hiPSC)-derived sympathetic neurons (SNs) to evaluate neuronal functional phenotype in LQT1. We generated hiPSC-SNs from two patients with LQT1 with a history of sympathetically triggered arrhythmia and KCNQ1 loss-of-function genotypes (c.781_782delinsTC and p.S349W/p.R518X). Characterization of hiPSC-SNs was performed using immunohistochemistry, enzyme-linked immunosorbent assay, and whole cell patch clamp electrophysiology, and functional LQT1 hiPSC-SN phenotypes compared with healthy control (WT) hiPSC-SNs. hiPSC-SNs stained positive for tyrosine hydroxylase, peripherin, KCNQ1, and secreted norepinephrine. hiPSC-SNs at 60 ± 2.2 days in vitro had healthy resting membrane potentials (-60 ± 1.3 mV), and fired rapid action potentials with mature kinetics in response to stimulation. Significant hyperactivity in LQT1 hiPSC-SNs was evident via increased norepinephrine release, increased spontaneous action potential frequency, increased total inward current density, and reduced afterhyperpolarization, compared with age-matched WT hiPSC-SNs. A significantly higher action potential frequency upon current injection and larger synaptic current amplitudes in compound heterozygous p.S349W/p.R518X hiPSC-SNs compared with heterozygous c.781_782delinsTC hiPSC-SNs was also observed, suggesting a potential genotype-phenotype correlation. Together, our data reveal increased neurotransmission and excitability in heterozygous and compound heterozygous patient-derived LQT1 sympathetic neurons, suggesting that the cellular arrhythmogenic potential in LQT1 is not restricted to cardiomyocytes.NEW & NOTEWORTHY Here, we present the first study of patient-derived LQT1 sympathetic neurons that are norepinephrine secreting, and electrophysiologically functional, in vitro. Our data reveal a novel LQT1 sympathetic neuronal phenotype of increased neurotransmission and excitability. The identified sympathetic neuronal hyperactivity phenotype is of particular relevance as it could contribute to the mechanisms underlying sympathetically triggered arrhythmia in LQT1.
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Affiliation(s)
- Annika Winbo
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand.,Department of Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand.,The Cardiac Inherited Disease Group (CIDG), Auckland, New Zealand.,Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
| | - Suganeya Ramanan
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Emily Eugster
- DeVos Cardiovascular Research Program Spectrum Health/Van Andel Research Institute, Grand Rapids, Michigan
| | - Annika Rydberg
- Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
| | - Stefan Jovinge
- DeVos Cardiovascular Research Program Spectrum Health/Van Andel Research Institute, Grand Rapids, Michigan.,Cardiovascular Institute, Stanford University of Medicine, Stanford, California
| | - Jonathan R Skinner
- Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand.,Department of Paediatric and Congenital Cardiac Services, Starship Children's Hospital, Auckland, New Zealand.,The Cardiac Inherited Disease Group (CIDG), Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Manaaki Mānawa Centre for Heart Research, University of Auckland, Auckland, New Zealand
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Zhao J, Aslanidi O, Kuklik P, Lee G, Tse G, Niederer S, Vigmond EJ. Editorial: Recent Advances in Understanding the Basic Mechanisms of Atrial Fibrillation Using Novel Computational Approaches. Front Physiol 2019; 10:1065. [PMID: 31551796 PMCID: PMC6736575 DOI: 10.3389/fphys.2019.01065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/02/2019] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jichao Zhao
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Oleg Aslanidi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Pawel Kuklik
- Department of Cardiology, University Heart Center Hamburg, Hamburg, Germany
| | - Geoffrey Lee
- Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Cardiology, University of Melbourne, Melbourne, VIC, Australia
| | - Gary Tse
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China.,Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
| | - Steven Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Edward J Vigmond
- IMB, UMR 5251, University of Bordeaux, Pessac, France.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
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3
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Affiliation(s)
- Stanley Nattel
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal; Departments of Medicine and Pharmacology and Therapeutics, McGill University, Montreal, Canada; Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.
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4
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Badone B, Ronchi C, Kotta MC, Sala L, Ghidoni A, Crotti L, Zaza A. Calmodulinopathy: Functional Effects of CALM Mutations and Their Relationship With Clinical Phenotypes. Front Cardiovasc Med 2018; 5:176. [PMID: 30619883 PMCID: PMC6297375 DOI: 10.3389/fcvm.2018.00176] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/22/2018] [Indexed: 12/16/2022] Open
Abstract
In spite of the widespread role of calmodulin (CaM) in cellular signaling, CaM mutations lead specifically to cardiac manifestations, characterized by remarkable electrical instability and a high incidence of sudden death at young age. Penetrance of the mutations is surprisingly high, thus postulating a high degree of functional dominance. According to the clinical patterns, arrhythmogenesis in CaM mutations can be attributed, in the majority of cases, to either prolonged repolarization (as in long-QT syndrome, LQTS phenotype), or to instability of the intracellular Ca2+ store (as in catecholamine-induced tachycardias, CPVT phenotype). This review discusses how mutations affect CaM signaling function and how this may relate to the distinct arrhythmia phenotypes/mechanisms observed in patients; this involves mechanistic interpretation of negative dominance and mutation-specific CaM-target interactions. Knowledge of the mechanisms involved may allow critical approach to clinical manifestations and aid in the development of therapeutic strategies for "calmodulinopathies," a recently identified nosological entity.
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Affiliation(s)
- Beatrice Badone
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Carlotta Ronchi
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Maria-Christina Kotta
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Luca Sala
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Alice Ghidoni
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Lia Crotti
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
- Department of Cardiovascular, Neural and Metabolic Sciences, San Luca Hospital, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Antonio Zaza
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
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Bögeholz N, Pauls P, Bauer BK, Schulte JS, Frommeyer G, Dechering DG, Boknik P, Kirchhefer U, Müller FU, Pott C, Eckardt L. Overexpression of the Na + /Ca 2+ exchanger influences ouabain-mediated spontaneous Ca 2+ activity but not positive inotropy. Fundam Clin Pharmacol 2018; 33:43-51. [PMID: 30092622 DOI: 10.1111/fcp.12404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 07/16/2018] [Accepted: 08/01/2018] [Indexed: 12/01/2022]
Abstract
Administration of digitalis in heart failure (HF) increases quality of life but does not carry a prognostic benefit. Digitalis is an indirect inhibitor of the Na+ /Ca2+ exchanger (NCX), which is overexpressed in HF. We therefore used the cardiac glycoside ouabain in Ca2+ imaging experiments and patch-clamp experiments in isolated ventricular myocytes from nonfailing transgenic NCX overexpressor mice (OE). In field-stimulated myocytes, ouabain (1-100 μm) increased the amplitude of the Ca2+ transient in OE and wild-type (WT) similarly. Ouabain-mediated spontaneous Ca2+ -activity was significantly more pronounced in OE compared to WT myocytes at higher concentrations (100 μm). Also, at very high concentrations (1000 μm) of ouabain, the number of cells with hypercontraction leading to cell death was higher in OE. Ouabain (10 μm) shortened the action potential duration in both genotypes. Our findings suggest that the proarrhythmic but not the inotropic effects of cardiac glycosides are enhanced by increased NCX expression. This may offer an explanation for the observed lack of prognostic benefit but increased quality of life in HF, which is accompanied by NCX upregulation.
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Affiliation(s)
- Nils Bögeholz
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Paul Pauls
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany.,Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Bastian K Bauer
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Jan S Schulte
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Gerrit Frommeyer
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Dirk G Dechering
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Frank U Müller
- Institut für Pharmakologie und Toxikologie, Universität Münster, Domagkstraße 12, 48149, Münster, Germany
| | - Christian Pott
- Department of Cardiology, Schüchtermann-Klinik, Ulmenallee 5-11, 49214, Bad Rothenfelde, Germany
| | - Lars Eckardt
- Klinik für Kardiologie II: Rhythmologie, Universitätsklinikum Münster, Albert-Schweitzer-Campus 1, Gebäude A1, 48149, Münster, Germany
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Abstract
In cardiac electrophysiology, there exist many sources of inter- and intra-personal variability. These include variability in conditions and environment, and genotypic and molecular diversity, including differences in expression and behavior of ion channels and transporters, which lead to phenotypic diversity (e.g., variable integrated responses at the cell, tissue, and organ levels). These variabilities play an important role in progression of heart disease and arrhythmia syndromes and outcomes of therapeutic interventions. Yet, the traditional in silico framework for investigating cardiac arrhythmias is built upon a parameter/property-averaging approach that typically overlooks the physiological diversity. Inspired by work done in genetics and neuroscience, new modeling frameworks of cardiac electrophysiology have been recently developed that take advantage of modern computational capabilities and approaches, and account for the variance in the biological data they are intended to illuminate. In this review, we outline the recent advances in statistical and computational techniques that take into account physiological variability, and move beyond the traditional cardiac model-building scheme that involves averaging over samples from many individuals in the construction of a highly tuned composite model. We discuss how these advanced methods have harnessed the power of big (simulated) data to study the mechanisms of cardiac arrhythmias, with a special emphasis on atrial fibrillation, and improve the assessment of proarrhythmic risk and drug response. The challenges of using in silico approaches with variability are also addressed and future directions are proposed.
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Affiliation(s)
| | | | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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7
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Ortega FA, Grandi E, Krogh-Madsen T, Christini DJ. Applications of Dynamic Clamp to Cardiac Arrhythmia Research: Role in Drug Target Discovery and Safety Pharmacology Testing. Front Physiol 2018; 8:1099. [PMID: 29354069 PMCID: PMC5758594 DOI: 10.3389/fphys.2017.01099] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 12/13/2017] [Indexed: 12/31/2022] Open
Abstract
Dynamic clamp, a hybrid-computational-experimental technique that has been used to elucidate ionic mechanisms underlying cardiac electrophysiology, is emerging as a promising tool in the discovery of potential anti-arrhythmic targets and in pharmacological safety testing. Through the injection of computationally simulated conductances into isolated cardiomyocytes in a real-time continuous loop, dynamic clamp has greatly expanded the capabilities of patch clamp outside traditional static voltage and current protocols. Recent applications include fine manipulation of injected artificial conductances to identify promising drug targets in the prevention of arrhythmia and the direct testing of model-based hypotheses. Furthermore, dynamic clamp has been used to enhance existing experimental models by addressing their intrinsic limitations, which increased predictive power in identifying pro-arrhythmic pharmacological compounds. Here, we review the recent advances of the dynamic clamp technique in cardiac electrophysiology with a focus on its future role in the development of safety testing and discovery of anti-arrhythmic drugs.
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Affiliation(s)
- Francis A Ortega
- Physiology, Biophysics, and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, United States
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Trine Krogh-Madsen
- Greenberg Division of Cardiology, Weill Cornell Medical College, New York, NY, United States
| | - David J Christini
- Physiology, Biophysics, and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, United States.,Greenberg Division of Cardiology, Weill Cornell Medical College, New York, NY, United States
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8
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Vidmar D, Krummen DE, Hayase J, Narayan SM, Ho G, Rappel WJ. Spatiotemporal Progression of Early Human Ventricular Fibrillation. JACC Clin Electrophysiol 2017; 3:1437-46. [PMID: 29238755 DOI: 10.1016/j.jacep.2017.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Objectives The objective of this study was to evaluate the spatio-temporal organization and progression of human ventricular fibrillation (VF) in the left (LV) and right (RV) ventricles. Background Studies suggest that localized sources contribute to VF maintenance, but the evolution of VF episodes has not been quantified. Methods Synchrony between electrograms recorded from 25 patients with induced VF is computed and used to define the Asynchronous Index (ASI), indicating regions which are out-of-step with surrounding tissue. Computer simulations show that ASI can identify the location of VF-maintaining sources, where larger values of ASImax correlate with more stable sources. Results Automated synchrony analysis shows elevated values of ASI in a majority of self-terminating episodes (LV: 8/9, RV: 7/8) and sustained episodes (LV: 11/11, RV: 12/12). The locations of ASImax in sustained episodes co-localize with rotor cores when rotational activity is simultaneously present in phase maps (LV: 8/8, RV: 5/7, p<.05). The distribution of ASImax differentiates self-terminating from sustained episodes (mean ASImax = 0.60±0.14 and 0.70±0.16, respectively; p=0.01). Across sustained episodes the LV exhibits an increase in ASImax with time. Conclusions Quantitative analysis identifies localized asynchronous regions that correlate with sources in VF, with sustained episodes evolving to exhibit more stable activation in the LV. This successive increase in stability indicates a stabilizing agent may be responsible for perpetuating fibrillation in a "migrate-and-capture" mechanism in the LV.
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Morgan R, Colman MA, Chubb H, Seemann G, Aslanidi OV. Slow Conduction in the Border Zones of Patchy Fibrosis Stabilizes the Drivers for Atrial Fibrillation: Insights from Multi-Scale Human Atrial Modeling. Front Physiol 2016; 7:474. [PMID: 27826248 PMCID: PMC5079097 DOI: 10.3389/fphys.2016.00474] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 10/03/2016] [Indexed: 01/12/2023] Open
Abstract
Introduction: The genesis of atrial fibrillation (AF) and success of AF ablation therapy have been strongly linked with atrial fibrosis. Increasing evidence suggests that patient-specific distributions of fibrosis may determine the locations of electrical drivers (rotors) sustaining AF, but the underlying mechanisms are incompletely understood. This study aims to elucidate a missing mechanistic link between patient-specific fibrosis distributions and AF drivers. Methods: 3D atrial models integrated human atrial geometry, rule-based fiber orientation, region-specific electrophysiology, and AF-induced ionic remodeling. A novel detailed model for an atrial fibroblast was developed, and effects of myocyte-fibroblast (M-F) coupling were explored at single-cell, 1D tissue and 3D atria levels. Left atrial LGE MRI datasets from 3 chronic AF patients were segmented to provide the patient-specific distributions of fibrosis. The data was non-linearly registered and mapped to the 3D atria model. Six distinctive fibrosis levels (0-healthy tissue, 5-dense fibrosis) were identified based on LGE MRI intensity and modeled as progressively increasing M-F coupling and decreasing atrial tissue coupling. Uniform 3D atrial model with diffuse (level 2) fibrosis was considered for comparison. Results: In single cells and tissue, the largest effect of atrial M-F coupling was on the myocyte resting membrane potential, leading to partial inactivation of sodium current and reduction of conduction velocity (CV). In the 3D atria, further to the M-F coupling, effects of fibrosis on tissue coupling greatly reduce atrial CV. AF was initiated by fast pacing in each 3D model with either uniform or patient-specific fibrosis. High variation in fibrosis distributions between the models resulted in varying complexity of AF, with several drivers emerging. In the diffuse fibrosis models, waves randomly meandered through the atria, whereas in each the patient-specific models, rotors stabilized in fibrotic regions. The rotors propagated slowly around the border zones of patchy fibrosis (levels 3-4), failing to spread into inner areas of dense fibrosis. Conclusion: Rotors stabilize in the border zones of patchy fibrosis in 3D atria, where slow conduction enable the development of circuits within relatively small regions. Our results can provide a mechanistic explanation for the clinical efficacy of ablation around fibrotic regions.
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Affiliation(s)
- Ross Morgan
- Division of Imaging Sciences and Biomedical Engineering, Department of Biomedical Engineering, King's College London London, UK
| | | | - Henry Chubb
- Division of Imaging Sciences and Biomedical Engineering, Department of Biomedical Engineering, King's College London London, UK
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center - Bad Krozingen, Medical Center - University of Freiburg Freiburg, Germany
| | - Oleg V Aslanidi
- Division of Imaging Sciences and Biomedical Engineering, Department of Biomedical Engineering, King's College London London, UK
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Affiliation(s)
- Jordi Heijman
- Faculty of Health, Medicine & Life Sciences, Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart & Vascular Center, University Duisburg-Essen, Essen, Germany
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11
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Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice, yet our understanding of the mechanisms that initiate and sustain this arrhythmia remains quite poor. Over the last 50 years, various mechanisms of AF have been proposed, yet none has been consistently observed in both experimental studies and in humans. Recently, there has been increasing interest in understanding how spiral waves or rotors - which are specific, organised forms of functional reentry - sustain human AF and how they might be therapeutic targets for catheter-based ablation. The following review describes the historical understanding of reentry and AF mechanisms from earlier in the 20th century, advances in our understanding of mechanisms that are able to sustain AF with a focus on rotors and complex fractionated atrial electrograms (CFAEs), and how the study of AF mechanisms has resulted in new strategies for treating AF with novel forms of catheter ablation.
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Affiliation(s)
- Jonathan W Waks
- Clinical Fellow in Cardiac Electrophysiology, Harvard Medical School, Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service, Beth Israel Deaconess Medical Center, Boston, US
| | - Mark E Josephson
- Herman C. Dana Professor of Medicine, Harvard Medical School, Chief of the Cardiovascular Division, Beth Israel Deaconess Medical Center and Director, Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service, Beth Israel Deaconess Medical Center, Boston, US
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12
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Krummen DE, Hayase J, Morris DJ, Ho J, Smetak MR, Clopton P, Rappel WJ, Narayan SM. Rotor stability separates sustained ventricular fibrillation from self-terminating episodes in humans. J Am Coll Cardiol 2014; 63:2712-21. [PMID: 24794115 DOI: 10.1016/j.jacc.2014.03.037] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 03/23/2014] [Accepted: 03/29/2014] [Indexed: 10/25/2022]
Abstract
OBJECTIVES This study mapped human ventricular fibrillation (VF) to define mechanistic differences between episodes requiring defibrillation versus those that spontaneously terminate. BACKGROUND VF is a leading cause of mortality; yet, episodes may also self-terminate. We hypothesized that the initial maintenance of human VF is dependent upon the formation and stability of VF rotors. METHODS We enrolled 26 consecutive patients (age 64 ± 10 years, n = 13 with left ventricular dysfunction) during ablation procedures for ventricular arrhythmias, using 64-electrode basket catheters in both ventricles to map VF prior to prompt defibrillation per the institutional review board-approved protocol. A total of 52 inductions were attempted, and 36 VF episodes were observed. Phase analysis was applied to identify biventricular rotors in the first 10 s or until VF terminated, whichever came first (11.4 ± 2.9 s to defibrillator charging). RESULTS Rotors were present in 16 of 19 patients with VF and in all patients with sustained VF. Sustained, but not self-limiting VF, was characterized by greater rotor stability: 1) rotors were present in 68 ± 17% of cycles in sustained VF versus 11 ± 18% of cycles in self-limiting VF (p < 0.001); and 2) maximum continuous rotations were greater in sustained (17 ± 11, range 7 to 48) versus self-limiting VF (1.1 ± 1.4, range 0 to 4, p < 0.001). Additionally, biventricular rotor locations in sustained VF were conserved across multiple inductions (7 of 7 patients, p = 0.025). CONCLUSIONS In patients with and without structural heart disease, the formation of stable rotors identifies individuals whose VF requires defibrillation from those in whom VF spontaneously self-terminates. Future work should define the mechanisms that stabilize rotors and evaluate whether rotor modulation may reduce subsequent VF risk.
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Affiliation(s)
- David E Krummen
- University of California San Diego, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California.
| | - Justin Hayase
- University of California San Diego, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California
| | - David J Morris
- University of California San Diego, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Jeffrey Ho
- University of California San Diego, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Miriam R Smetak
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Paul Clopton
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | | | - Sanjiv M Narayan
- University of California San Diego, San Diego, California; Veterans Affairs San Diego Healthcare System, San Diego, California
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13
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Martin CA, Siedlecka U, Kemmerich K, Lawrence J, Cartledge J, Guzadhur L, Brice N, Grace AA, Schwiening C, Terracciano CM, Huang CLH. Reduced Na(+) and higher K(+) channel expression and function contribute to right ventricular origin of arrhythmias in Scn5a+/- mice. Open Biol 2013; 2:120072. [PMID: 22773948 PMCID: PMC3390792 DOI: 10.1098/rsob.120072] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/11/2012] [Indexed: 12/17/2022] Open
Abstract
Brugada syndrome (BrS) is associated with ventricular tachycardia originating particularly in the right ventricle (RV). We explore electrophysiological features predisposing to such arrhythmic tendency and their possible RV localization in a heterozygotic Scn5a+/− murine model. Nav1.5 mRNA and protein expression were lower in Scn5a+/− than wild-type (WT), with a further reduction in the RV compared with the left ventricle (LV). RVs showed higher expression levels of Kv4.2, Kv4.3 and KChIP2 in both Scn5a+/− and WT. Action potential upstroke velocity and maximum Na+ current (INa) density were correspondingly decreased in Scn5a+/−, with a further reduction in the RV. The voltage dependence of inactivation was shifted to more negative values in Scn5a+/−. These findings are predictive of a localized depolarization abnormality leading to slowed conduction. Persistent Na+ current (IpNa) density was decreased in a similar pattern to INa. RV transient outward current (Ito) density was greater than LV in both WT and Scn5a+/−, and had larger time constants of inactivation. These findings were also consistent with the observation that AP durations were smallest in the RV of Scn5a+/−, fulfilling predictions of an increased heterogeneity of repolarization as an additional possible electrophysiological mechanism for arrhythmogenesis in BrS.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK.
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Nishijima Y, Sridhar A, Bonilla I, Velayutham M, Khan M, Terentyeva R, Li C, Kuppusamy P, Elton TS, Terentyev D, Györke S, Zweier JL, Cardounel AJ, Carnes CA. Tetrahydrobiopterin depletion and NOS2 uncoupling contribute to heart failure-induced alterations in atrial electrophysiology. Cardiovasc Res 2011; 91:71-9. [PMID: 21460065 PMCID: PMC3112023 DOI: 10.1093/cvr/cvr087] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 02/24/2011] [Accepted: 03/25/2011] [Indexed: 01/14/2023] Open
Abstract
AIMS Heart failure is a common antecedent to atrial fibrillation; both heart failure and atrial fibrillation are associated with increased myocardial oxidative stress. Chronic canine heart failure reduces atrial action potential duration and atrial refractoriness. We hypothesized that inducible nitric oxide synthase 2 (NOS2) contributes to atrial oxidative stress and electrophysiologic alterations. METHODS AND RESULTS A 16-week canine tachypacing model of heart failure was used (n= 21). At 10 weeks, dogs were randomized to either placebo (n = 12) or active treatment (n = 9) with NOS cofactor, tetrahydrobiopterin (BH(4), 50 mg), and NOS substrate (L-arginine, 3 g) twice daily for 6 weeks. A group of matched controls (n = 7) was used for comparison. Heart failure increased atrial NOS2 and reduced atrial BH(4), while L-arginine was unchanged. Treatment reduced inducible atrial fibrillation and normalized the heart failure-induced shortening of the left atrial myocyte action potential duration. Treatment increased atrial [BH(4)] while [L-arginine] was unchanged. Treatment did not improve left ventricular function or dimensions. Heart failure-induced reductions in atrial [BH(4)] resulted in NOS uncoupling, as measured by NO and superoxide anion (O(2)(·-)) production, while BH(4) and L-arginine treatment normalized NO and O(2)(·-). Heart failure resulted in left atrial oxidative stress, which was attenuated by BH(4) and L-arginine treatment. CONCLUSION Chronic non-ischaemic heart failure results in atrial oxidative stress and electrophysiologic abnormalities by depletion of BH(4) and uncoupling of NOS2. Modulation of NOS2 activity by repletion of BH(4) may be a safe and effective approach to reduce the frequency of atrial arrhythmias during heart failure.
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Affiliation(s)
- Yoshinori Nishijima
- College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA
| | - Arun Sridhar
- Glaxo Smith Kline, Park Road, Ware, Herts SG12 0DP, UK
| | - Ingrid Bonilla
- College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA
| | - Murugesan Velayutham
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Center for Biomedical EPR Spectroscopy and Imaging, Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Mahmood Khan
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Center for Biomedical EPR Spectroscopy and Imaging, Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Radmila Terentyeva
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Chun Li
- College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA
| | - Periannan Kuppusamy
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Center for Biomedical EPR Spectroscopy and Imaging, Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Terry S. Elton
- College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Dmitry Terentyev
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Sandor Györke
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jay L. Zweier
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Center for Biomedical EPR Spectroscopy and Imaging, Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Arturo J. Cardounel
- Department of Anesthesiology, The Ohio State University, Columbus, OH 43210, USA
| | - Cynthia A. Carnes
- College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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