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Tjostheim SS, Showers A, Obernberger C, Shear M. Association of sotalol versus atenolol therapy with survival in dogs with severe subaortic stenosis. J Vet Cardiol 2023; 48:19-30. [PMID: 37307692 DOI: 10.1016/j.jvc.2023.05.003] [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: 08/25/2022] [Revised: 04/17/2023] [Accepted: 05/04/2023] [Indexed: 06/14/2023]
Abstract
INTRODUCTION/OBJECTIVES Dogs with severe subaortic stenosis (SAS) are at risk of dying suddenly from fatal arrhythmias. Survival is not improved when treated with pure beta-adrenergic receptor (β)-blockers; however, the effect of other antiarrhythmic drugs on survival is unknown. Sotalol is both a β-blocker and a class III antiarrhythmic drug; the combination of these differing mechanisms may provide benefit to dogs with severe SAS. The primary objective of this study was to compare survival in dogs with severe SAS that were treated with either sotalol or atenolol. The secondary objective was to evaluate the effect of pressure gradient (PG), age, breed, and aortic regurgitation on survival. ANIMALS Forty-three client-owned dogs. MATERIALS AND METHODS Retrospective cohort study. Medical records of dogs diagnosed with severe SAS (PG ≥ 80 mmHg) between 2003 and 2020 were reviewed. RESULTS No statistical difference was identified in survival time between dogs treated with sotalol (n = 14) and those treated with atenolol (n = 29) when evaluating all-cause mortality (p=0.172) or cardiac-related mortality (p=0.157). Of the dogs that died suddenly, survival time was significantly shorter in dogs treated with sotalol compared to those treated with atenolol (p=0.046). Multivariable analysis showed that PG (p=0.002) and treatment with sotalol (p=0.050) negatively influenced survival in the dogs that died suddenly. CONCLUSIONS Sotalol did not have a significant effect on survival overall but may increase the risk of sudden death in dogs with severe SAS compared to atenolol.
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Affiliation(s)
- S S Tjostheim
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr., Madison, WI 53706, USA.
| | - A Showers
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr., Madison, WI 53706, USA
| | - C Obernberger
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr., Madison, WI 53706, USA
| | - M Shear
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr., Madison, WI 53706, USA
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2
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Anderson RD, Nayyar S, Masse S, Lambiase PD, Nanthakumar K. Wave tail mapping to guide ablation therapy for ventricular arrhythmias. Heart Rhythm 2023; 20:461-470. [PMID: 36756940 DOI: 10.1016/j.hrthm.2022.10.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/13/2022] [Accepted: 10/24/2022] [Indexed: 12/23/2022]
Affiliation(s)
- Robert D Anderson
- Hull Family Cardiac Fibrillation Management Laboratory, Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada
| | - Sachin Nayyar
- Department of Cardiology, Townsville University Hospital, James Cook University, Douglas, Queensland, Australia
| | - Stephane Masse
- Hull Family Cardiac Fibrillation Management Laboratory, Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada
| | - Pier D Lambiase
- Barts Heart Centre, Barts Health National Health Service Trust, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Kumaraswamy Nanthakumar
- Hull Family Cardiac Fibrillation Management Laboratory, Division of Cardiology, University Health Network, Toronto General Hospital, Toronto, Ontario, Canada.
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3
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Dorninger F, Kiss A, Rothauer P, Stiglbauer-Tscholakoff A, Kummer S, Fallatah W, Perera-Gonzalez M, Hamza O, König T, Bober MB, Cavallé-Garrido T, Braverman NE, Forss-Petter S, Pifl C, Bauer J, Bittner RE, Helbich TH, Podesser BK, Todt H, Berger J. Overlapping and Distinct Features of Cardiac Pathology in Inherited Human and Murine Ether Lipid Deficiency. Int J Mol Sci 2023; 24:1884. [PMID: 36768204 PMCID: PMC9914995 DOI: 10.3390/ijms24031884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/21/2023] Open
Abstract
Inherited deficiency in ether lipids, a subgroup of glycerophospholipids with unique biochemical and biophysical properties, evokes severe symptoms in humans resulting in a multi-organ syndrome. Mouse models with defects in ether lipid biosynthesis have widely been used to understand the pathophysiology of human disease and to study the roles of ether lipids in various cell types and tissues. However, little is known about the function of these lipids in cardiac tissue. Previous studies included case reports of cardiac defects in ether-lipid-deficient patients, but a systematic analysis of the impact of ether lipid deficiency on the mammalian heart is still missing. Here, we utilize a mouse model of complete ether lipid deficiency (Gnpat KO) to accomplish this task. Similar to a subgroup of human patients with rhizomelic chondrodysplasia punctata (RCDP), a fraction of Gnpat KO fetuses present with defects in ventricular septation, presumably evoked by a developmental delay. We did not detect any signs of cardiomyopathy but identified increased left ventricular end-systolic and end-diastolic pressure in middle-aged ether-lipid-deficient mice. By comprehensive electrocardiographic characterization, we consistently found reduced ventricular conduction velocity, as indicated by a prolonged QRS complex, as well as increased QRS and QT dispersion in the Gnpat KO group. Furthermore, a shift of the Wenckebach point to longer cycle lengths indicated depressed atrioventricular nodal function. To complement our findings in mice, we analyzed medical records and performed electrocardiography in ether-lipid-deficient human patients, which, in contrast to the murine phenotype, indicated a trend towards shortened QT intervals. Taken together, our findings demonstrate that the cardiac phenotype upon ether lipid deficiency is highly heterogeneous, and although the manifestations in the mouse model only partially match the abnormalities in human patients, the results add to our understanding of the physiological role of ether lipids and emphasize their importance for proper cardiac development and function.
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Affiliation(s)
- Fabian Dorninger
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Attila Kiss
- Center for Biomedical Research, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Peter Rothauer
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstrasse 13a, 1090 Vienna, Austria
| | - Alexander Stiglbauer-Tscholakoff
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Molecular and Structural Preclinical Imaging, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Stefan Kummer
- Neuromuscular Research Department, Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, 1090 Vienna, Austria
| | - Wedad Fallatah
- Department of Genetic Medicine, King AbdulAziz University, Jeddah 21589, Saudi Arabia
- Department of Human Genetics and Pediatrics, Montreal Children’s Hospital, McGill University, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada
| | - Mireia Perera-Gonzalez
- Center for Biomedical Research, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Ouafa Hamza
- Center for Biomedical Research, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Theresa König
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Michael B. Bober
- Skeletal Dysplasia Program, Nemours Children’s Hospital, 1600 Rockland Road, Wilmington, DE 19803, USA
| | - Tiscar Cavallé-Garrido
- Department of Pediatrics, Division of Cardiology, Montreal Children’s Hospital, McGill University, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada
| | - Nancy E. Braverman
- Department of Human Genetics and Pediatrics, Montreal Children’s Hospital, McGill University, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada
| | - Sonja Forss-Petter
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Christian Pifl
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Jan Bauer
- Department of Neuroimmunology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
| | - Reginald E. Bittner
- Neuromuscular Research Department, Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, 1090 Vienna, Austria
| | - Thomas H. Helbich
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Molecular and Structural Preclinical Imaging, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Bruno K. Podesser
- Center for Biomedical Research, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Hannes Todt
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstrasse 13a, 1090 Vienna, Austria
| | - Johannes Berger
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
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4
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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5
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Koya T, Watanabe M, Natsui H, Kadosaka T, Koizumi T, Nakao M, Hagiwara H, Kamada R, Temma T, Anzai T. Pharmacological nNOS inhibition modified small-conductance Ca 2+-activated K + channel without altering Ca 2+ dynamics. Am J Physiol Heart Circ Physiol 2022; 323:H869-H878. [PMID: 36149772 DOI: 10.1152/ajpheart.00252.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Atrial fibrillation (AF) is associated with electrical remodeling processes that promote a substrate for the maintenance of AF. Although the small-conductance Ca2+-activated K+ (SK) channel is a key factor in atrial electrical remodeling, the mechanism of its activation remains unclear. Regional nitric oxide (NO) production by neuronal nitric oxide synthase (nNOS) is involved in atrial electrical remodeling. In this study, atrial tachyarrhythmia (ATA) induction and optical mapping were performed on perfused rat hearts. nNOS is pharmacologically inhibited by S-methylthiocitrulline (SMTC). The influence of the SK channel was examined using a specific channel inhibitor, apamin (APA). Parameters such as action potential duration (APD), conduction velocity, and calcium transient (CaT) were evaluated using voltage and calcium optical mapping. The dominant frequency was examined in the analysis of AF dynamics. SMTC (100 nM) increased the inducibility of ATA and apamin (100 nM) mitigated nNOS inhibition-induced arrhythmogenicity. SMTC caused abbreviations and enhanced the spatial dispersion of APD, which was reversed by apamin. By contrast, conduction velocity and other parameters associated with CaT were not affected by SMTC or apamin administration. Apamin reduced the frequency of SMTC-induced ATA. In summary, nNOS inhibition abbreviates APD by modifying the SK channels. A specific SK channel blocker, apamin, mitigated APD abbreviation without alteration of CaT, implying an underlying mechanism of posttranslational modification of SK channels.NEW & NOTEWORTHY We demonstrated that pharmacological nNOS inhibition increased the atrial arrhythmia inducibility and a specific small-conductance Ca2+-activated K+ channel blocker, apamin, reversed the enhanced atrial arrhythmia inducibility. Apamin mitigated APD abbreviation without alteration of Ca2+ transient, implying an underlying mechanism of posttranslational modification of SK channels.
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Affiliation(s)
- Taro Koya
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Masaya Watanabe
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hiroyuki Natsui
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takahide Kadosaka
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takuya Koizumi
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Motoki Nakao
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hikaru Hagiwara
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Rui Kamada
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Taro Temma
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Toshihisa Anzai
- Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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6
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George RM, Guo S, Firulli BA, Rubart M, Firulli AB. Neonatal Deletion of Hand1 and Hand2 within Murine Cardiac Conduction System Reveals a Novel Role for HAND2 in Rhythm Homeostasis. J Cardiovasc Dev Dis 2022; 9:214. [PMID: 35877576 PMCID: PMC9324487 DOI: 10.3390/jcdd9070214] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/17/2022] [Accepted: 06/30/2022] [Indexed: 02/04/2023] Open
Abstract
The cardiac conduction system, a network of specialized cells, is required for the functioning of the heart. The basic helix loop helix factors Hand1 and Hand2 are required for cardiac morphogenesis and have been implicated in cardiac conduction system development and maintenance. Here we use embryonic and post-natal specific Cre lines to interrogate the role of Hand1 and Hand2 in the function of the murine cardiac conduction system. Results demonstrate that loss of HAND1 in the post-natal conduction system does not result in any change in electrocardiogram parameters or within the ventricular conduction system as determined by optical voltage mapping. Deletion of Hand2 within the post-natal conduction system results in sex-dependent reduction in PR interval duration in these mice, suggesting a novel role for HAND2 in regulating the atrioventricular conduction. Surprisingly, results show that loss of both HAND factors within the post-natal conduction system does not cause any consistent changes in cardiac conduction system function. Deletion of Hand2 in the embryonic left ventricle results in inconsistent prolongation of PR interval and susceptibility to atrial arrhythmias. Thus, these results suggest a novel role for HAND2 in homeostasis of the murine cardiac conduction system and that HAND1 loss potentially rescues the shortened HAND2 PR phenotype.
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Affiliation(s)
- Rajani M. George
- Herman B Wells Center for Pediatric Research, Departments of Pediatrics, Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN 46202, USA; (R.M.G.); (B.A.F.)
| | - Shuai Guo
- Division of Cardiology, Department of Medicine, The Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
| | - Beth A. Firulli
- Herman B Wells Center for Pediatric Research, Departments of Pediatrics, Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN 46202, USA; (R.M.G.); (B.A.F.)
| | - Michael Rubart
- Herman B Wells Center for Pediatric Research, Departments of Pediatrics, Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN 46202, USA; (R.M.G.); (B.A.F.)
- Division of Cardiology, Department of Medicine, The Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
| | - Anthony B. Firulli
- Herman B Wells Center for Pediatric Research, Departments of Pediatrics, Anatomy and Medical and Molecular Genetics, Indiana Medical School, Indianapolis, IN 46202, USA; (R.M.G.); (B.A.F.)
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7
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Rieger M, Dellenbach C, Vom Berg J, Beil-Wagner J, Maguy A, Rohr S. Enabling comprehensive optogenetic studies of mouse hearts by simultaneous opto-electrical panoramic mapping and stimulation. Nat Commun 2021; 12:5804. [PMID: 34608155 PMCID: PMC8490461 DOI: 10.1038/s41467-021-26039-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/15/2021] [Indexed: 11/09/2022] Open
Abstract
During the last decade, cardiac optogenetics has turned into an essential tool for investigating cardiac function in general and for assessing functional interactions between different myocardial cell types in particular. To advance exploitation of the unique research opportunities offered by this method, we develop a panoramic opto-electrical measurement and stimulation (POEMS) system for mouse hearts. The core of the experimental platform is composed of 294 optical fibers and 64 electrodes that form a cup which embraces the entire ventricular surface of mouse hearts and enables straightforward ‘drop&go’ experimentation. The flexible assignment of fibers and electrodes to recording or stimulation tasks permits a precise tailoring of experiments to the specific requirements of individual optogenetic constructs thereby avoiding spectral congestion. Validation experiments with hearts from transgenic animals expressing the optogenetic voltage reporters ASAP1 and ArcLight-Q239 demonstrate concordance of simultaneously recorded panoramic optical and electrical activation maps. The feasibility of single fiber optical stimulation is proven with hearts expressing the optogenetic voltage actuator ReaChR. Adaptation of the POEMS system to larger hearts and incorporation of additional sensors can be achieved by redesigning the system-core accordingly. Current cardiac mapping systems provide either electrical or optical readouts. Here the authors report a panoramic opto-electrical measurement and stimulation (POEMS) system which embraces the entire ventricular surface of mouse hearts, allowing flexible combinations of optical and electrical recording and stimulation modalities.
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Affiliation(s)
- Michael Rieger
- Department of Physiology, University of Bern, Bühlplatz 5, Bern, Switzerland
| | | | - Johannes Vom Berg
- Institute of Laboratory Animal Science, University of Zürich, Wagistrasse 12, Schlieren, Switzerland
| | - Jane Beil-Wagner
- Institute of Laboratory Animal Science, University of Zürich, Wagistrasse 12, Schlieren, Switzerland
| | - Ange Maguy
- Department of Physiology, University of Bern, Bühlplatz 5, Bern, Switzerland
| | - Stephan Rohr
- Department of Physiology, University of Bern, Bühlplatz 5, Bern, Switzerland.
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8
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Integrated transcriptomics and epigenomics reveal chamber-specific and species-specific characteristics of human and mouse hearts. PLoS Biol 2021; 19:e3001229. [PMID: 34003819 PMCID: PMC8130971 DOI: 10.1371/journal.pbio.3001229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 04/12/2021] [Indexed: 12/02/2022] Open
Abstract
DNA methylation, chromatin accessibility, and gene expression represent different levels information in biological process, but a comprehensive multiomics analysis of the mammalian heart is lacking. Here, we applied nucleosome occupancy and methylome sequencing, which detected DNA methylation and chromatin accessibility simultaneously, as well as RNA-seq, for multiomics analysis of the 4 chambers of adult and fetal human hearts, and adult mouse hearts. Our results showed conserved region-specific patterns in the mammalian heart at transcriptome and DNA methylation level. Adult and fetal human hearts showed distinct features in DNA methylome, chromatin accessibility, and transcriptome. Novel long noncoding RNAs were identified in the human heart, and the gene expression profiles of major cardiovascular diseases associated genes were displayed. Furthermore, cross-species comparisons revealed human-specific and mouse-specific differentially expressed genes between the atria and ventricles. We also reported the relationship among multiomics and found there was a bell-shaped relationship between gene-body methylation and expression in the human heart. In general, our study provided comprehensive spatiotemporal and evolutionary insights into the regulation of gene expression in the heart. Multi-omic analyses of the four chambers of the human and mouse heart, including transcriptome, DNA methylation and chromatin accessibility, reveals characteristic patterns of gene regulation at the level of heart regions.
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9
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Papageorgiou N, Srinivasan NT. Dynamic High-density Functional Substrate Mapping Improves Outcomes in Ischaemic Ventricular Tachycardia Ablation: Sense Protocol Functional Substrate Mapping and Other Functional Mapping Techniques. Arrhythm Electrophysiol Rev 2021; 10:38-44. [PMID: 33936742 PMCID: PMC8076974 DOI: 10.15420/aer.2020.28] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Post-infarct-related ventricular tachycardia (VT) occurs due to reentry over surviving fibres within ventricular scar tissue. The mapping and ablation of patients in VT remains a challenge when VT is poorly tolerated and in cases in which VT is non-sustained or not inducible. Conventional substrate mapping techniques are limited by the ambiguity of substrate characterisation methods and the variety of mapping tools, which may record signals differently based on their bipolar spacing and electrode size. Real world data suggest that outcomes from VT ablation remain poor in terms of freedom from recurrent therapy using conventional techniques. Functional substrate mapping techniques, such as single extrastimulus protocol mapping, identify regions of unmasked delayed potentials, which, by nature of their dynamic and functional components, may play a critical role in sustaining VT. These methods may improve substrate mapping of VT, potentially making ablation safer and more reproducible, and thereby improving the outcomes. Further large-scale studies are needed.
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Affiliation(s)
- Nikolaos Papageorgiou
- Department of Cardiac Electrophysiology, Barts Heart Centre, St Bartholomew's Hospital, London, UK
| | - Neil T Srinivasan
- Department of Cardiac Electrophysiology, Barts Heart Centre, St Bartholomew's Hospital, London, UK.,Institute of Cardiovascular Science, University College London, London, UK.,Department of Cardiac Electrophysiology, Essex Cardiothoracic Centre, Basildon, UK
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10
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Saadeh K, Shivkumar K, Jeevaratnam K. Targeting the β-adrenergic receptor in the clinical management of congenital long QT syndrome. Ann N Y Acad Sci 2020; 1474:27-46. [PMID: 32901453 DOI: 10.1111/nyas.14425] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/10/2020] [Accepted: 06/09/2020] [Indexed: 01/01/2023]
Abstract
The long QT syndrome (LQTS) is largely treated pharmacologically with β-blockers, despite the role of sympathetic activity in LQTS being poorly understood. Using the trigger-substrate model of cardiac arrhythmias in this review, we amalgamate current experimental and clinical data from both animal and human studies to explain the mechanism of adrenergic stimulation and blockade on LQT arrhythmic risk and hence assess the efficacy of β-adrenoceptor blockade in the management of LQTS. In LQTS1 and LQTS2, sympathetic stimulation increases arrhythmic risk by enhancing early afterdepolarizations and transmural dispersion of repolarization. β-Blockers successfully reduce cardiac events by reducing these triggers and substrates; however, these effects are less marked in LQTS2 compared with LQTS1. In LQTS3, clinical and experimental investigations of the effects of sympathetic stimulation and β-blocker use have produced contradictory findings, resulting in significant clinical uncertainty. We offer explanations for these contradicting results relating to study sample size, the dose of the β-blocker administered associated with its off-target Na+ channel effects, as well as the type of β-blocker used. We conclude that the antiarrhythmic efficacy of β-blockers is a genotype-specific phenomenon, and hence the use of β-blockers in clinical practice should be genotype dependent.
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Affiliation(s)
- Khalil Saadeh
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Kalyanam Shivkumar
- UCLA Cardiac Arrhythmia Centre, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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11
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Kim TY, Jeng P, Hwang J, Pfeiffer Z, Patel D, Cooper LL, Kossidas K, Centracchio J, Peng X, Koren G, Qu Z, Choi BR. Short-Long Heart Rate Variation Increases Dispersion of Action Potential Duration in Long QT Type 2 Transgenic Rabbit Model. Sci Rep 2019; 9:14849. [PMID: 31619700 PMCID: PMC6795902 DOI: 10.1038/s41598-019-51230-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/24/2019] [Indexed: 01/21/2023] Open
Abstract
The initiation of polymorphic ventricular tachycardia in long QT syndrome type 2 (LQT2) has been associated with a characteristic ECG pattern of short-long RR intervals. We hypothesize that this characteristic pattern increases APD dispersion in LQT2, thereby promoting arrhythmia. We investigated APD dispersion and its dependence on two previous cycle lengths (CLs) in transgenic rabbit models of LQT2, LQT1, and their littermate controls (LMC) using random stimulation protocols. The results show that the short-long RR pattern was associated with a larger APD dispersion in LQT2 but not in LQT1 rabbits. The multivariate analyses of APD as a function of two previous CLs (APDn = C + α1CLn−1 + α2CLn−2) showed that α1 (APD restitution slope) is largest and heterogeneous in LQT2 but uniform in LQT1, enhancing APD dispersion under long CLn−1 in LQT2. The α2 (short-term memory) was negative in LQT2 while positive in LQT1, and the spatial pattern of α1 was inversely correlated to α2 in LQT2, which explains why a short-long combination causes a larger APD dispersion in LQT2 but not in LQT1 rabbits. In conclusion, short-long RR pattern increased APD dispersion only in LQT2 rabbits through heterogeneous APD restitution and the short-term memory, underscoring the genotype-specific triggering of arrhythmias in LQT syndrome.
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Affiliation(s)
- Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Paul Jeng
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - JungMin Hwang
- College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - Zachary Pfeiffer
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Divyang Patel
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Leroy L Cooper
- Biology Department, Vassar College, Poughkeepsie, NY, USA
| | - Konstantinos Kossidas
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Jason Centracchio
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Xuwen Peng
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA.
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12
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Wang W, Zhang S, Ni H, Garratt CJ, Boyett MR, Hancox JC, Zhang H. Mechanistic insight into spontaneous transition from cellular alternans to arrhythmia-A simulation study. PLoS Comput Biol 2018; 14:e1006594. [PMID: 30500818 PMCID: PMC6291170 DOI: 10.1371/journal.pcbi.1006594] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/12/2018] [Accepted: 10/23/2018] [Indexed: 02/01/2023] Open
Abstract
Cardiac electrical alternans (CEA), manifested as T-wave alternans in ECG, is a clinical biomarker for predicting cardiac arrhythmias and sudden death. However, the mechanism underlying the spontaneous transition from CEA to arrhythmias remains incompletely elucidated. In this study, multiscale rabbit ventricular models were used to study the transition and a potential role of INa in perpetuating such a transition. It was shown CEA evolved into either concordant or discordant action potential (AP) conduction alternans in a homogeneous one-dimensional tissue model, depending on tissue AP duration and conduction velocity (CV) restitution properties. Discordant alternans was able to cause conduction failure in the model, which was promoted by impaired sodium channel with either a reduced or increased channel current. In a two-dimensional homogeneous tissue model, a combined effect of rate- and curvature-dependent CV broke-up alternating wavefronts at localised points, facilitating a spontaneous transition from CEA to re-entry. Tissue inhomogeneity or anisotropy further promoted break-up of re-entry, leading to multiple wavelets. Similar observations have also been seen in human atrial cellular and tissue models. In conclusion, our results identify a mechanism by which CEA spontaneously evolves into re-entry without a requirement for premature ventricular complexes or pre-existing tissue heterogeneities, and demonstrated the important pro-arrhythmic role of impaired sodium channel activity. These findings are model-independent and have potential human relevance.
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Affiliation(s)
- Wei Wang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Shanzhuo Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Haibo Ni
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Clifford J. Garratt
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Mark R. Boyett
- Manchester Heart Centre, Manchester Royal Infirmary, Manchester, United Kingdom
| | - Jules C. Hancox
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Physiology, Pharmacology and Neuroscience, and Cardiovascular Research Laboratories, School of Medical Sciences, University of Bristol, Bristol, United Kingdom
| | - Henggui Zhang
- Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
- 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, Sichuan, China
- Space Institute of Southern China, Shenzhen, China
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13
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Wen Q, Gandhi K, Capel RA, Hao G, O'Shea C, Neagu G, Pearcey S, Pavlovic D, Terrar DA, Wu J, Faggian G, Camelliti P, Lei M. Transverse cardiac slicing and optical imaging for analysis of transmural gradients in membrane potential and Ca 2+ transients in murine heart. J Physiol 2018; 596:3951-3965. [PMID: 29928770 PMCID: PMC6117587 DOI: 10.1113/jp276239] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/12/2018] [Indexed: 11/18/2022] Open
Abstract
Key points A robust cardiac slicing approach was developed for optical mapping of transmural gradients in transmembrane potential (Vm) and intracellular Ca2+ transient (CaT) of murine heart. Significant transmural gradients in Vm and CaT were observed in the left ventricle. Frequency‐dependent action potentials and CaT alternans were observed in all ventricular regions with rapid pacing, with significantly greater incidence in the endocardium than epicardium. The observations demonstrate the feasibility of our new approach to cardiac slicing for systematic analysis of intrinsic transmural and regional gradients in Vm and CaT.
Abstract Transmural and regional gradients in membrane potential and Ca2+ transient in the murine heart are largely unexplored. Here, we developed and validated a robust approach which combines transverse ultra‐thin cardiac slices and high resolution optical mapping to enable systematic analysis of transmural and regional gradients in transmembrane potential (Vm) and intracellular Ca2+ transient (CaT) across the entire murine ventricles. The voltage dye RH237 or Ca2+ dye Rhod‐2 AM were loaded through the coronary circulation using a Langendorff perfusion system. Short‐axis slices (300 μm thick) were prepared from the entire ventricles (from the apex to the base) by using a high‐precision vibratome. Action potentials (APs) and CaTs were recorded with optical mapping during steady‐state baseline and rapid pacing. Significant transmural gradients in Vm and CaT were observed in the left ventricle, with longer AP duration (APD50 and APD75) and CaT duration (CaTD50 and CaTD75) in the endocardium compared with that in the epicardium. No significant regional gradients were observed along the apico‐basal axis of the left ventricle. Interventricular gradients were detected with significantly shorter APD50, APD75 and CaTD50 in the right ventricle compared with left ventricle and ventricular septum. During rapid pacing, AP and CaT alternans were observed in most ventricular regions, with significantly greater incidence in the endocardium in comparison with epicardium. In conclusion, these observations demonstrate the feasibility of our new approach to cardiac slicing for systematic analysis of intrinsic transmural and regional gradients in Vm and CaT in murine ventricular tissue. A robust cardiac slicing approach was developed for optical mapping of transmural gradients in transmembrane potential (Vm) and intracellular Ca2+ transient (CaT) of murine heart. Significant transmural gradients in Vm and CaT were observed in the left ventricle. Frequency‐dependent action potentials and CaT alternans were observed in all ventricular regions with rapid pacing, with significantly greater incidence in the endocardium than epicardium. The observations demonstrate the feasibility of our new approach to cardiac slicing for systematic analysis of intrinsic transmural and regional gradients in Vm and CaT.
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Affiliation(s)
- Q Wen
- Institution of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - K Gandhi
- Medical School, University of Verona, Verona, Italy
| | - Rebecca A Capel
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - G Hao
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, 6400, China
| | - C O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - G Neagu
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - S Pearcey
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - D Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Derek A Terrar
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - J Wu
- Institution of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - G Faggian
- Medical School, University of Verona, Verona, Italy
| | | | - M Lei
- Department of Pharmacology, University of Oxford, Oxford, UK.,Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, 6400, China
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14
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Overexpression of Cx43 in cells of the myocardial scar: Correction of post-infarct arrhythmias through heterotypic cell-cell coupling. Sci Rep 2018; 8:7145. [PMID: 29739982 PMCID: PMC5940892 DOI: 10.1038/s41598-018-25147-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 04/06/2018] [Indexed: 12/16/2022] Open
Abstract
Ventricular tachycardia (VT) is the most common and potentially lethal complication following myocardial infarction (MI). Biological correction of the conduction inhomogeneity that underlies re-entry could be a major advance in infarction therapy. As minimal increases in conduction of infarcted tissue markedly influence VT susceptibility, we reasoned that enhanced propagation of the electrical signal between non-excitable cells within a resolving infarct might comprise a simple means to decrease post-infarction arrhythmia risk. We therefore tested lentivirus-mediated delivery of the gap-junction protein Connexin 43 (Cx43) into acute myocardial lesions. Cx43 was expressed in (myo)fibroblasts and CD45+ cells within the scar and provided prominent and long lasting arrhythmia protection in vivo. Optical mapping of Cx43 injected hearts revealed enhanced conduction velocity within the scar, indicating Cx43-mediated electrical coupling between myocytes and (myo)fibroblasts. Thus, Cx43 gene therapy, by direct in vivo transduction of non-cardiomyocytes, comprises a simple and clinically applicable biological therapy that markedly reduces post-infarction VT.
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15
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Cao H, Wang X, Ying S, Huang C. AMPKα2 deficiency enhanced susceptibility to ventricular arrhythmias in mice by the role of β-adrenoceptor signaling. Exp Biol Med (Maywood) 2018; 243:708-714. [PMID: 29597876 DOI: 10.1177/1535370218767389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
AMP-activated protein kinase-α2 is the main catalytic subunit of the heart, which is mainly located in cardiac myocytes. The effect of AMP-activated protein kinase-α2 on the cardiac electrophysiology is barely studied. From the previous study, it is possible that AMP-activated protein kinase-α2 may have some effect on the electrophysiology of the heart. To prove the hypothesis, we used the AMP-activated protein kinase-α2 knockout (AMPKα2-/-) mice to estimate the electrophysiological characteristics of AMPKα2-/- mice and try to find the mechanism between them. We used AMP-activated protein kinase-α2 gene knockout (AMPKα2-/-) mice and control wild-type mice as the experimental animals. In the experiment, we measured the monophasic action potential duration and test the inducibility to ventricular arrhythmia in isolated mice heart with and without β-adrenoceptor antagonist metoprolol. Meanwhile, plasma concentration of catecholamine was collected. We found that AMPKα2-/- significantly shortened 90% repolarization of monophasic action potential (MAP) (MAPD90) than wild-type (47.4 ± 2.6 ms vs. 55.5 ± 2.4 ms, n = 10, P < 0.05) and were more vulnerable to be induced to ventricular arrhythmias (70% (7/10) vs. 10% (1/10), P < 0.05), accompanied by the higher concentration of catecholamine (epinephrine: 1.75 ± 0.18 nmol/L vs. 0.68 ± 0.10 nmol/L n = 10, P < 0.05; norepinephrine: 9.56 ± 0.71 nmol/L vs. 2.52 ± 0.31 nmol/L n = 10, P < 0.05). The shortening of MAPD90 and increased inducibility to ventricular arrhythmias of AMPKα2-/- could almost be abolished when perfusion with β-adrenoceptor antagonist metoprolol. It indicated that the β-adrenoceptor activation resulting from catecholamine release was mainly responsible for the relating changes of electrophysiology of AMPKα2-/-. It had great clinical significance, as in patients who had problem with AMP-activated protein kinase-α2 gene, we might use β-adrenoceptor antagonists as the prevention of arrhythmias in future. Impact statement As far as we know, this is the first time the role of AMP-activated protein kinase-α2 (AMPKα2) on the cardiac electrophysiology is explored, and we found that the β-adrenoceptor activation resulting from catecholamine release was mainly responsible for the changes of electrophysiology related to the absence of AMPKα2. This has great clinical significance, as in patients who have problems with AMPKα2 gene, we may use β-adrenoceptor antagonists for the prevention of arrhythmias in future.
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Affiliation(s)
- Hong Cao
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,2 Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Xin Wang
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Shaozheng Ying
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Congxin Huang
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
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16
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Yeo JM, Tse V, Kung J, Lin HY, Lee YT, Kwan J, Yan BP, Tse G. Isolated heart models for studying cardiac electrophysiology: a historical perspective and recent advances. J Basic Clin Physiol Pharmacol 2018; 28:191-200. [PMID: 28063261 DOI: 10.1515/jbcpp-2016-0110] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/12/2016] [Indexed: 01/25/2023]
Abstract
Experimental models used in cardiovascular research range from cellular to whole heart preparations. Isolated whole hearts show higher levels of structural and functional integration than lower level models such as tissues or cellular fragments. Cardiovascular diseases are multi-factorial problems that are dependent on highly organized structures rather than on molecular or cellular components alone. This article first provides a general introduction on the animal models of cardiovascular diseases. It is followed by a detailed overview and a historical perspective of the different isolated heart systems with a particular focus on the Langendorff perfusion method for the study of cardiac arrhythmias. The choice of species, perfusion method, and perfusate composition are discussed in further detail with particular considerations of the theoretical and practical aspects of experimental settings.
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Affiliation(s)
- Jie Ming Yeo
- School of Medicine, Imperial College London, London
| | - Vivian Tse
- Department of Physiology, McGill University, Montreal, Quebec
| | - Judy Kung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Hiu Yu Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Yee Ting Lee
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Joseph Kwan
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R
| | - Bryan P Yan
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne
| | - Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R
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17
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London B. United We Stand; Divided We Fibrillate? Circ Res 2017; 121:1302-1303. [PMID: 29217706 DOI: 10.1161/circresaha.117.312176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Barry London
- From the Division of Cardiovascular Medicine, University of Iowa, Iowa City.
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18
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Goergen CJ, Chen HH, Sakadžić S, Srinivasan VJ, Sosnovik DE. Microstructural characterization of myocardial infarction with optical coherence tractography and two-photon microscopy. Physiol Rep 2017; 4:4/18/e12894. [PMID: 27650248 PMCID: PMC5037910 DOI: 10.14814/phy2.12894] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/07/2016] [Indexed: 11/24/2022] Open
Abstract
Myocardial infarction leads to complex changes in the fiber architecture of the heart. Here, we present a novel optical approach to characterize these changes in intact hearts in three dimensions. Optical coherence tomography (OCT) was used to derive a depth‐resolved field of orientation on which tractography was performed. Tractography of healthy myocardium revealed a smooth linear transition in fiber inclination or helix angle from the epicardium to endocardium. Conversely, in infarcted hearts, no coherent microstructure could be identified in the infarct with OCT. Additional characterization of the infarct was performed by the measurement of light attenuation and with two‐photon microscopy. Myofibers were imaged using autofluorescence and collagen fibers using second harmonic generation. This revealed the presence of two distinct microstructural patterns in areas of the infarct with high light attenuation. In the presence of residual myofibers, the surrounding collagen fibers were aligned in a coherent manner parallel to the myofibers. In the absence of residual myofibers, the collagen fibers were randomly oriented and lacked any microstructural coherence. The presence of residual myofibers thus exerts a profound effect on the microstructural properties of the infarct scar and consequently the risk of aneurysm formation and arrhythmias. Catheter‐based approaches to segment and image myocardial microstructure in humans are feasible and could play a valuable role in guiding the development of strategies to improve infarct healing.
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Affiliation(s)
- Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts
| | - Howard H Chen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts Cardiovascular Research Center, Department of Medicine, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts
| | - Vivek J Srinivasan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts Department of Biomedical Engineering, University of California Davis, Davis, California
| | - David E Sosnovik
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts Cardiovascular Research Center, Department of Medicine, Massachusetts General Hospital Harvard Medical School, Charlestown, Massachusetts
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19
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Vaseghi M, Salavatian S, Rajendran PS, Yagishita D, Woodward WR, Hamon D, Yamakawa K, Irie T, Habecker BA, Shivkumar K. Parasympathetic dysfunction and antiarrhythmic effect of vagal nerve stimulation following myocardial infarction. JCI Insight 2017; 2:86715. [PMID: 28814663 DOI: 10.1172/jci.insight.86715] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 07/06/2017] [Indexed: 01/22/2023] Open
Abstract
Myocardial infarction causes sympathetic activation and parasympathetic dysfunction, which increase risk of sudden death due to ventricular arrhythmias. Mechanisms underlying parasympathetic dysfunction are unclear. The aim of this study was to delineate consequences of myocardial infarction on parasympathetic myocardial neurotransmitter levels and the function of parasympathetic cardiac ganglia neurons, and to assess electrophysiological effects of vagal nerve stimulation on ventricular arrhythmias in a chronic porcine infarct model. While norepinephrine levels decreased, cardiac acetylcholine levels remained preserved in border zones and viable myocardium of infarcted hearts. In vivo neuronal recordings demonstrated abnormalities in firing frequency of parasympathetic neurons of infarcted animals. Neurons that were activated by parasympathetic stimulation had low basal firing frequency, while neurons that were suppressed by left vagal nerve stimulation had abnormally high basal activity. Myocardial infarction increased sympathetic inputs to parasympathetic convergent neurons. However, the underlying parasympathetic cardiac neuronal network remained intact. Augmenting parasympathetic drive with vagal nerve stimulation reduced ventricular arrhythmia inducibility by decreasing ventricular excitability and heterogeneity of repolarization of infarct border zones, an area with known proarrhythmic potential. Preserved acetylcholine levels and intact parasympathetic neuronal pathways can explain the electrical stabilization of infarct border zones with vagal nerve stimulation, providing insight into its antiarrhythmic benefit.
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Affiliation(s)
- Marmar Vaseghi
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and.,Molecular Cellular and Integrative Physiology Interdepartmental Program, UCLA, Los Angeles, California, USA
| | - Siamak Salavatian
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and.,Molecular Cellular and Integrative Physiology Interdepartmental Program, UCLA, Los Angeles, California, USA
| | - Pradeep S Rajendran
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and.,Molecular Cellular and Integrative Physiology Interdepartmental Program, UCLA, Los Angeles, California, USA
| | - Daigo Yagishita
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and
| | | | - David Hamon
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and
| | | | - Tadanobu Irie
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and
| | - Beth A Habecker
- Department of Physiology & Pharmacology and.,Department of Medicine Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Kalyanam Shivkumar
- Cardiac Arrhythmia Center.,Neurocardiology Research Center of Excellence, and.,Molecular Cellular and Integrative Physiology Interdepartmental Program, UCLA, Los Angeles, California, USA
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20
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Kember G, Ardell JL, Shivkumar K, Armour JA. Recurrent myocardial infarction: Mechanisms of free-floating adaptation and autonomic derangement in networked cardiac neural control. PLoS One 2017; 12:e0180194. [PMID: 28692680 PMCID: PMC5503241 DOI: 10.1371/journal.pone.0180194] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 06/12/2017] [Indexed: 12/20/2022] Open
Abstract
The cardiac nervous system continuously controls cardiac function whether or not pathology is present. While myocardial infarction typically has a major and catastrophic impact, population studies have shown that longer-term risk for recurrent myocardial infarction and the related potential for sudden cardiac death depends mainly upon standard atherosclerotic variables and autonomic nervous system maladaptations. Investigative neurocardiology has demonstrated that autonomic control of cardiac function includes local circuit neurons for networked control within the peripheral nervous system. The structural and adaptive characteristics of such networked interactions define the dynamics and a new normal for cardiac control that results in the aftermath of recurrent myocardial infarction and/or unstable angina that may or may not precipitate autonomic derangement. These features are explored here via a mathematical model of cardiac regulation. A main observation is that the control environment during pathology is an extrapolation to a setting outside prior experience. Although global bounds guarantee stability, the resulting closed-loop dynamics exhibited while the network adapts during pathology are aptly described as 'free-floating' in order to emphasize their dependence upon details of the network structure. The totality of the results provide a mechanistic reasoning that validates the clinical practice of reducing sympathetic efferent neuronal tone while aggressively targeting autonomic derangement in the treatment of ischemic heart disease.
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Affiliation(s)
- Guy Kember
- Dept. of Engineering Mathematics and Internetworking/Faculty of Engineering/Dalhousie University, Halifax, NS, Canada
- * E-mail:
| | - Jeffrey L. Ardell
- David Geffen School of Medicine/Cardiac Arrhythmia Center, University of California – Los Angeles (UCLA), Los Angeles, CA, United States of America
| | - Kalyanam Shivkumar
- David Geffen School of Medicine/Cardiac Arrhythmia Center, University of California – Los Angeles (UCLA), Los Angeles, CA, United States of America
| | - J. Andrew Armour
- David Geffen School of Medicine/Cardiac Arrhythmia Center, University of California – Los Angeles (UCLA), Los Angeles, CA, United States of America
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21
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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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22
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Edwards AG, Louch WE. Species-Dependent Mechanisms of Cardiac Arrhythmia: A Cellular Focus. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2017; 11:1179546816686061. [PMID: 28469490 PMCID: PMC5392019 DOI: 10.1177/1179546816686061] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/20/2016] [Indexed: 12/17/2022]
Abstract
Although ventricular arrhythmia remains a leading cause of morbidity and mortality, available antiarrhythmic drugs have limited efficacy. Disappointing progress in the development of novel, clinically relevant antiarrhythmic agents may partly be attributed to discrepancies between humans and animal models used in preclinical testing. However, such differences are at present difficult to predict, requiring improved understanding of arrhythmia mechanisms across species. To this end, we presently review interspecies similarities and differences in fundamental cardiomyocyte electrophysiology and current understanding of the mechanisms underlying the generation of afterdepolarizations and reentry. We specifically highlight patent shortcomings in small rodents to reproduce cellular and tissue-level arrhythmia substrate believed to be critical in human ventricle. Despite greater ease of translation from larger animal models, discrepancies remain and interpretation can be complicated by incomplete knowledge of human ventricular physiology due to low availability of explanted tissue. We therefore point to the benefits of mathematical modeling as a translational bridge to understanding and treating human arrhythmia.
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Affiliation(s)
- Andrew G Edwards
- Center for Biomedical Computing, Simula Research Laboratory, Lysaker, Norway.,Center for Cardiological Innovation, Simula Research Laboratory, Lysaker, Norway.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo, Oslo, Norway
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23
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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24
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Ramratnam M, Salama G, Sharma RK, Wang DWR, Smith SH, Banerjee SK, Huang XN, Gifford LM, Pruce ML, Gabris BE, Saba S, Shroff SG, Ahmad F. Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization. PLoS One 2016; 11:e0167681. [PMID: 27936050 PMCID: PMC5147943 DOI: 10.1371/journal.pone.0167681] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/18/2016] [Indexed: 02/06/2023] Open
Abstract
Most studies of the mechanisms leading to hereditary dilated cardiomyopathy (DCM) have been performed in reconstituted in vitro systems. Genetically engineered murine models offer the opportunity to dissect these mechanisms in vivo. We generated a gene-targeted knock-in murine model of the autosomal dominant Arg141Trp (R141W) mutation in Tnnt2, which was first described in a human family with DCM. Mice heterozygous for the mutation (Tnnt2R141W/+) recapitulated the human phenotype, developing left ventricular dilation and reduced contractility. There was a gene dosage effect, so that the phenotype in Tnnt2R141W/+mice was attenuated by transgenic overexpression of wildtype Tnnt2 mRNA transcript. Male mice exhibited poorer survival than females. Biomechanical studies on skinned fibers from Tnnt2R141W/+ hearts showed a significant decrease in pCa50 (-log[Ca2+] required for generation of 50% of maximal force) relative to wildtype hearts, indicating Ca2+ desensitization. Optical mapping studies of Langendorff-perfused Tnnt2R141W/+ hearts showed marked increases in diastolic and peak systolic intracellular Ca2+ ([Ca2+]i), and prolonged systolic rise and diastolic fall of [Ca2+]i. Perfused Tnnt2R141W/+ hearts had slower intrinsic rates in sinus rhythm and reduced peak heart rates in response to isoproterenol. Tnnt2R141W/+ hearts exhibited a reduction in phosphorylated phospholamban relative to wildtype mice. However, crossing Tnnt2R141W/+ mice with phospholamban knockout (Pln-/-) mice, which exhibit increased Ca2+ transients and contractility, had no effect on the DCM phenotype. We conclude that the Tnnt2 R141W mutation causes a Ca2+ desensitization and mice adapt by increasing Ca2+-transient amplitudes, which impairs Ca2+ handling dynamics, metabolism and responses to β-adrenergic activation.
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Affiliation(s)
- Mohun Ramratnam
- Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison, WI, United States of America
- Cardiology Section, Medical Service, William. S. Middleton Memorial Veterans Hospital, Madison, WI, United States of America
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Guy Salama
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Ravi K. Sharma
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - David Wen Rui Wang
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Stephen H. Smith
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Sanjay K. Banerjee
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Xueyin N. Huang
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Lindsey M. Gifford
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA, United States of America
| | - Michele L. Pruce
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Bethann E. Gabris
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Samir Saba
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Sanjeev G. Shroff
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Ferhaan Ahmad
- UPMC Heart and Vascular Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Abboud Cardiovascular Research Center, University of Iowa, Iowa City, IA, United States of America
- * E-mail:
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25
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Optogenetics design of mechanistically-based stimulation patterns for cardiac defibrillation. Sci Rep 2016; 6:35628. [PMID: 27748433 PMCID: PMC5066272 DOI: 10.1038/srep35628] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/04/2016] [Indexed: 12/31/2022] Open
Abstract
Current rescue therapies for life-threatening arrhythmias ignore the pathological electro-anatomical substrate and base their efficacy on a generalized electrical discharge. Here, we developed an all-optical platform to examine less invasive defibrillation strategies. An ultrafast wide-field macroscope was developed to optically map action potential propagation with a red-shifted voltage sensitive dye in whole mouse hearts. The macroscope was implemented with a random-access scanning head capable of drawing arbitrarily-chosen stimulation patterns with sub-millisecond temporal resolution allowing precise epicardial activation of Channelrhodopsin2 (ChR2). We employed this optical system in the setting of ventricular tachycardia to optimize mechanistic, multi-barrier cardioversion/defibrillation patterns. Multiple regions of conduction block were created with a very high cardioversion efficiency but with lower energy requirements as compared to whole ventricle interventions to interrupt arrhythmias. This work demonstrates that defibrillation energies can be substantially reduced by applying discrete stimulation patterns and promotes the progress of current anti-arrhythmic strategies.
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26
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Choy L, Yeo JM, Tse V, Chan SP, Tse G. Cardiac disease and arrhythmogenesis: Mechanistic insights from mouse models. IJC HEART & VASCULATURE 2016; 12:1-10. [PMID: 27766308 PMCID: PMC5064289 DOI: 10.1016/j.ijcha.2016.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/02/2016] [Indexed: 12/19/2022]
Abstract
The mouse is the second mammalian species, after the human, in which substantial amount of the genomic information has been analyzed. With advances in transgenic technology, mutagenesis is now much easier to carry out in mice. Consequently, an increasing number of transgenic mouse systems have been generated for the study of cardiac arrhythmias in ion channelopathies and cardiomyopathies. Mouse hearts are also amenable to physical manipulation such as coronary artery ligation and transverse aortic constriction to induce heart failure, radiofrequency ablation of the AV node to model complete AV block and even implantation of a miniature pacemaker to induce cardiac dyssynchrony. Last but not least, pharmacological models, despite being simplistic, have enabled us to understand the physiological mechanisms of arrhythmias and evaluate the anti-arrhythmic properties of experimental agents, such as gap junction modulators, that may be exert therapeutic effects in other cardiac diseases. In this article, we examine these in turn, demonstrating that primary inherited arrhythmic syndromes are now recognized to be more complex than abnormality in a particular ion channel, involving alterations in gene expression and structural remodelling. Conversely, in cardiomyopathies and heart failure, mutations in ion channels and proteins have been identified as underlying causes, and electrophysiological remodelling are recognized pathological features. Transgenic techniques causing mutagenesis in mice are extremely powerful in dissecting the relative contributions of different genes play in producing disease phenotypes. Mouse models can serve as useful systems in which to explore how protein defects contribute to arrhythmias and direct future therapy.
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Affiliation(s)
- Lois Choy
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, SW7 2AZ, UK
| | - Vivian Tse
- Department of Physiology, McGill University, Canada
| | - Shing Po Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
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27
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Goff RP, Howard BT, Quallich SG, Iles TL, Iaizzo PA. The novel in vitro reanimation of isolated human and large mammalian heart-lung blocs. BMC PHYSIOLOGY 2016; 16:4. [PMID: 27259478 PMCID: PMC4893289 DOI: 10.1186/s12899-016-0023-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 05/24/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND In vitro isolated heart preparations are valuable tools for the study of cardiac anatomy and physiology, as well as for preclinical device testing. Such preparations afford investigators a high level of hemodynamic control, independent of host or systemic interactions. Here we hypothesize that recovered human and swine heart-lung blocs can be reanimated using a clear perfusate and elicit viable cardiodynamic and pulmonic function. Further, this approach will facilitate multimodal imaging, which is particularly valuable for the study of both functional anatomy and device-tissue interactions. Five human and 18 swine heart-lung preparations were procured using techniques analogous to those for cardiac transplant. Specimens were then rewarmed and reperfused using modifications of a closed circuit, isolated, beating and ventilated heart-lung preparation. Positive pressure mechanical ventilation was also employed, and epicardial defibrillation was applied to elicit native cardiac sinus rhythm. Videoscopy, fluoroscopy, ultrasound, and infrared imaging were performed for anatomical and experimental study. RESULTS Systolic and diastolic left ventricular pressures observed for human and swine specimens were 68/2 ± 11/7 and 74/3 ± 17/5 mmHg, respectively, with associated native heart rates of 80 ± 7 and 96 ± 16 beats per minute. High-resolution imaging within functioning human pulmonary vasculature was obtained among other anatomies of interest. Note that one human specimen elicited poor cardiac performance post defibrillation. CONCLUSIONS We report the first dynamic videoscopic images of the pulmonary vasculature during viable cardiopulmonary function in isolated reanimated heart-lung blocs. This experimental approach provides unique in vitro opportunities for the study of novel medical therapeutics applied to large mammalian, including human, heart-lung specimens.
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Affiliation(s)
- Ryan P Goff
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Brian T Howard
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Stephen G Quallich
- Departments of Biomedical Engineering, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.,Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Tinen L Iles
- Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA
| | - Paul A Iaizzo
- Departments of Surgery, University of Minnesota, 420 Delaware St. SE, B172 Mayo, Minneapolis, MN, 55455, USA.
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28
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Ruiz M, Gélinas R, Vaillant F, Lauzier B, Des Rosiers C. Metabolic Tracing Using Stable Isotope-Labeled Substrates and Mass Spectrometry in the Perfused Mouse Heart. Methods Enzymol 2015; 561:107-47. [PMID: 26358903 DOI: 10.1016/bs.mie.2015.06.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There has been a resurgence of interest for the field of cardiac metabolism catalyzed by evidence demonstrating a role of metabolic dysregulation in the pathogenesis of heart disease as well as the increased need for new therapeutic targets for patients with these diseases. In this regard, measuring substrate fluxes is critical in providing insight into the dynamics of cellular metabolism and in delineating the regulation of metabolite production and utilization. This chapter provides a comprehensive description of concepts, guidelines, and tips to assess metabolic fluxes relevant to energy substrate metabolism using (13)C-labeled substrates and (13)C-isotopomer analysis by gas chromatography-mass spectrometry (GC-MS), and the ex vivo working heart as study model. The focus will be on the mouse and on flux parameters, which are commonly assessed in the field, namely, those relevant to substrate selection for energy metabolism, specifically the relative contribution of carbohydrate (glucose, lactate, and pyruvate) and fatty acid oxidation to acetyl-CoA formation for citrate synthesis, glycolysis, as well as anaplerosis. We provide detailed procedures for the heart isolation and perfusion in the working mode as well as for sample processing for metabolite extraction and analysis by GC-MS and subsequent data processing for calculation of metabolic flux parameters. Finally, we address practical considerations and discuss additional applications and future challenges.
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Affiliation(s)
- Matthieu Ruiz
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada; Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Roselle Gélinas
- Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Fanny Vaillant
- IHU Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux, Université de Bordeaux, Bordeaux, France; Inserm U1045 Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France
| | | | - Christine Des Rosiers
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada; Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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29
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Gautam M, Fujita D, Kimura K, Ichikawa H, Izawa A, Hirose M, Kashihara T, Yamada M, Takahashi M, Ikeda U, Shiba Y. Transplantation of adipose tissue-derived stem cells improves cardiac contractile function and electrical stability in a rat myocardial infarction model. J Mol Cell Cardiol 2015; 81:139-49. [PMID: 25724725 DOI: 10.1016/j.yjmcc.2015.02.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 01/08/2023]
Abstract
The transplantation of adipose tissue-derived stem cells (ADSCs) improves cardiac contractility after myocardial infarction (MI); however, little is known about the electrophysiological consequences of transplantation. The purpose of this study was to clarify whether the transplantation of ADSCs increases or decreases the incidence of ventricular tachyarrhythmias (VT) in a rat model of MI. MI was induced experimentally by permanent occlusion of the left anterior descending artery of Lewis rats. ADSCs were harvested from GFP-transgenic rats, and were cultured until passage four. ADSCs (10×10(6)) resuspended in 100μL saline or pro-survival cocktail (PSC), which enhances cardiac graft survival, were injected directly into syngeneic rat hearts 1week after MI. The recipients of ADSCs suspended in PSC had a larger graft area compared with those receiving ASDCs suspended in saline at 1week post-transplantation (number of graft cells/section: 148.7±10.6 vs. 22.4±3.4, p<0.05, n=5/group). Thereafter, all ADSC recipients were transplanted with ASDCs in PSC. ADSCs were transplanted into infarcted hearts, and the mechanical and electrophysiological functions were assessed. Echocardiography revealed that ADSC recipients had improved contractile function compared with those receiving PSC vehicle (fractional shortening: 21.1±0.9 vs. 14.1±1.2, p<0.05, n≥12/group). Four weeks post-transplantation, VT was induced via in vivo programmed electrical stimulation. The recipients of ADSCs showed a significantly lower incidence of induced VT compared with the control (31.3% vs. 83.3%, p<0.05, n≥12/group). To understand the electrical activity following transplantation, we performed ex vivo optical mapping using a voltage sensitive dye, and found that ADSC transplantation decreased conduction velocity and its dispersion in the peri-infarct area. These results suggest that ADSC transplantation improved cardiac mechanical and electrophysiological functions in subacute MI.
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Affiliation(s)
- Milan Gautam
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan
| | - Daiki Fujita
- Department of Anatomy and Organ Technology, Shinshu University, Matsumoto, Japan; Department of Biotechnology and Biomedical Engineering, Institute for Biomedical Sciences, Shinshu University, Matsumoto, Japan
| | - Kazuhiro Kimura
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan
| | - Hinako Ichikawa
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan
| | - Atsushi Izawa
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan
| | - Masamichi Hirose
- Department of Molecular and Cellular Pharmacology, Iwate Medical University, Iwate, Japan
| | | | | | - Masafumi Takahashi
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Uichi Ikeda
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan
| | - Yuji Shiba
- Department of Cardiovascular Medicine, Shinshu University, Matsumoto, Japan; Department of Biotechnology and Biomedical Engineering, Institute for Biomedical Sciences, Shinshu University, Matsumoto, Japan.
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30
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Clemen CS, Stöckigt F, Strucksberg KH, Chevessier F, Winter L, Schütz J, Bauer R, Thorweihe JM, Wenzel D, Schlötzer-Schrehardt U, Rasche V, Krsmanovic P, Katus HA, Rottbauer W, Just S, Müller OJ, Friedrich O, Meyer R, Herrmann H, Schrickel JW, Schröder R. The toxic effect of R350P mutant desmin in striated muscle of man and mouse. Acta Neuropathol 2015; 129:297-315. [PMID: 25394388 PMCID: PMC4309020 DOI: 10.1007/s00401-014-1363-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/14/2014] [Accepted: 10/30/2014] [Indexed: 01/09/2023]
Abstract
Mutations of the human desmin gene on chromosome 2q35 cause autosomal dominant, autosomal recessive and sporadic forms of protein aggregation myopathies and cardiomyopathies. We generated R349P desmin knock-in mice, which harbor the ortholog of the most frequently occurring human desmin missense mutation R350P. These mice develop age-dependent desmin-positive protein aggregation pathology, skeletal muscle weakness, dilated cardiomyopathy, as well as cardiac arrhythmias and conduction defects. For the first time, we report the expression level and subcellular distribution of mutant versus wild-type desmin in our mouse model as well as in skeletal muscle specimens derived from human R350P desminopathies. Furthermore, we demonstrate that the missense-mutant desmin inflicts changes of the subcellular localization and turnover of desmin itself and of direct desmin-binding partners. Our findings unveil a novel principle of pathogenesis, in which not the presence of protein aggregates, but disruption of the extrasarcomeric intermediate filament network leads to increased mechanical vulnerability of muscle fibers. These structural defects elicited at the myofiber level finally impact the entire organ and subsequently cause myopathy and cardiomyopathy.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/pathology
- Arrhythmias, Cardiac/physiopathology
- Cardiomyopathies/pathology
- Cardiomyopathies/physiopathology
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Dilated/physiopathology
- Cytoskeleton/metabolism
- Cytoskeleton/pathology
- Desmin/genetics
- Desmin/metabolism
- Disease Models, Animal
- Escherichia coli
- Gene Knock-In Techniques
- Heart Ventricles/pathology
- Heart Ventricles/physiopathology
- Humans
- Mice, Transgenic
- Muscle Weakness/pathology
- Muscle Weakness/physiopathology
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Muscular Dystrophies/pathology
- Muscular Dystrophies/physiopathology
- Mutation, Missense
- Myocardium/pathology
- RNA, Messenger/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sf9 Cells
- Spodoptera
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Affiliation(s)
- Christoph S. Clemen
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Florian Stöckigt
- Department of Internal Medicine II, University Hospital Bonn, 53105 Bonn, Germany
| | - Karl-Heinz Strucksberg
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Institute of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Frederic Chevessier
- Institute of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Lilli Winter
- Institute of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Johanna Schütz
- Institute of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Ralf Bauer
- Department of Internal Medicine III, University Hospital Heidelberg, 69120 Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | | | - Daniela Wenzel
- Institute of Physiology I, Life and Brain Center, University of Bonn, 53127 Bonn, Germany
| | | | - Volker Rasche
- Department of Internal Medicine II, University Hospital Ulm, 89081 Ulm, Germany
- Core Facility Small Animal Imaging, University of Ulm, 89081 Ulm, Germany
| | - Pavle Krsmanovic
- Functional Architecture of the Cell, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Hugo A. Katus
- Department of Internal Medicine III, University Hospital Heidelberg, 69120 Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | - Wolfgang Rottbauer
- Department of Internal Medicine II, University Hospital Ulm, 89081 Ulm, Germany
| | - Steffen Just
- Department of Internal Medicine II, University Hospital Ulm, 89081 Ulm, Germany
| | - Oliver J. Müller
- Department of Internal Medicine III, University Hospital Heidelberg, 69120 Heidelberg, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Heidelberg, Germany
| | - Oliver Friedrich
- Institute of Medical Biotechnology, University of Erlangen, 91052 Erlangen, Germany
| | - Rainer Meyer
- Institute of Physiology II, Medical Faculty, University of Bonn, 53115 Bonn, Germany
| | - Harald Herrmann
- Functional Architecture of the Cell, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Jan Wilko Schrickel
- Department of Internal Medicine II, University Hospital Bonn, 53105 Bonn, Germany
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
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31
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Lu XL, Rubart M. Micron-scale voltage and [Ca(2+)]i imaging in the intact heart. Front Physiol 2014; 5:451. [PMID: 25520663 PMCID: PMC4251286 DOI: 10.3389/fphys.2014.00451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 11/03/2014] [Indexed: 12/03/2022] Open
Abstract
Studies in isolated cardiomyocytes have provided tremendous information at the cellular and molecular level concerning regulation of transmembrane voltage (Vm) and intracellular calcium ([Ca2+]i). The ability to use the information gleaned to gain insight into the function of ion channels and Ca2+ handling proteins in a more complex system, e.g., the intact heart, has remained a challenge. We have developed laser scanning fluorescence microscopy-based approaches to monitor, at the sub-cellular to multi-cellular level in the immobilized, Langendorff-perfused mouse heart, dynamic changes in [Ca2+]i and Vm. This article will review the use of single- or dual-photon laser scanning microscopy [Ca2+]i imaging in conjunction with transgenic reporter technology to (a) interrogate the extent to which transplanted, donor-derived myocytes or cardiac stem cell-derived de novo myocytes are capable of forming a functional syncytium with the pre-existing myocardium, using entrainment of [Ca2+]i transients by the electrical activity of the recipient heart as a surrogate for electrical coupling, and (b) characterize the Ca2+ handling phenotypes of cellular implants. Further, we will review the ability of laser scanning fluorescence microscopy in conjunction with a fast-response voltage-sensitive to resolve, on a subcellular level in Langendorff-perfused mouse hearts, Vm dynamics that typically occur during the course of a cardiac action potential. Specifically, the utility of this technique to measure microscopic-scale voltage gradients in the normal and diseased heart is discussed.
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Affiliation(s)
- Xiao-Long Lu
- Riley Heart Research Center, Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine Indianapolis, IN, USA
| | - Michael Rubart
- Riley Heart Research Center, Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine Indianapolis, IN, USA
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Yu TY, Syeda F, Holmes AP, Osborne B, Dehghani H, Brain KL, Kirchhof P, Fabritz L. An automated system using spatial oversampling for optical mapping in murine atria. Development and validation with monophasic and transmembrane action potentials. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:340-8. [PMID: 25130572 PMCID: PMC4210664 DOI: 10.1016/j.pbiomolbio.2014.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 12/19/2022]
Abstract
We developed and validated a new optical mapping system for quantification of electrical activation and repolarisation in murine atria. The system makes use of a novel 2nd generation complementary metal-oxide-semiconductor (CMOS) camera with deliberate oversampling to allow both assessment of electrical activation with high spatial and temporal resolution (128 × 2048 pixels) and reliable assessment of atrial murine repolarisation using post-processing of signals. Optical recordings were taken from isolated, superfused and electrically stimulated murine left atria. The system reliably describes activation sequences, identifies areas of functional block, and allows quantification of conduction velocities and vectors. Furthermore, the system records murine atrial action potentials with comparable duration to both monophasic and transmembrane action potentials in murine atria.
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Affiliation(s)
- Ting Yue Yu
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK; Doctoral Training Centre for Physical Sciences of Imaging in the Biomedical Sciences (PSIBS), University of Birmingham, UK
| | - Fahima Syeda
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Andrew P Holmes
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Benjamin Osborne
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Hamid Dehghani
- Doctoral Training Centre for Physical Sciences of Imaging in the Biomedical Sciences (PSIBS), University of Birmingham, UK; School of Computer Science, College of Engineering and Physical Sciences, University of Birmingham, UK
| | - Keith L Brain
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Paulus Kirchhof
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK
| | - Larissa Fabritz
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, UK.
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Filippi S, Gizzi A, Cherubini C, Luther S, Fenton FH. Mechanistic insights into hypothermic ventricular fibrillation: the role of temperature and tissue size. Europace 2014; 16:424-34. [PMID: 24569897 PMCID: PMC3934849 DOI: 10.1093/europace/euu031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 01/27/2014] [Indexed: 12/26/2022] Open
Abstract
AIMS Hypothermia is well known to be pro-arrhythmic, yet it has beneficial effects as a resuscitation therapy and valuable during intracardiac surgeries. Therefore, we aim to study the mechanisms that induce fibrillation during hypothermia. A better understanding of the complex spatiotemporal dynamics of heart tissue as a function of temperature will be useful in managing the benefits and risks of hypothermia. METHODS AND RESULTS We perform two-dimensional numerical simulations by using a minimal model of cardiac action potential propagation fine-tuned on experimental measurements. The model includes thermal factors acting on the ionic currents and the gating variables to correctly reproduce experimentally recorded restitution curves at different temperatures. Simulations are implemented using WebGL, which allows long simulations to be performed as they run close to real time. We describe (i) why fibrillation is easier to induce at low temperatures, (ii) that there is a minimum size required for fibrillation that depends on temperature, (iii) why the frequency of fibrillation decreases with decreasing temperature, and (iv) that regional cooling may be an anti-arrhythmic therapy for small tissue sizes however it may be pro-arrhythmic for large tissue sizes. CONCLUSION Using a mathematical cardiac cell model, we are able to reproduce experimental observations, quantitative experimental results, and discuss possible mechanisms and implications of electrophysiological changes during hypothermia.
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Affiliation(s)
- Simonetta Filippi
- Nonlinear Physics and Mathematical Modeling Laboratory, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
- International Center for Relativistic Astrophysics—I.C.R.A, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
| | - Alessio Gizzi
- Nonlinear Physics and Mathematical Modeling Laboratory, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
- International Center for Relativistic Astrophysics—I.C.R.A, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
| | - Christian Cherubini
- Nonlinear Physics and Mathematical Modeling Laboratory, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
- International Center for Relativistic Astrophysics—I.C.R.A, University Campus Bio-Medico of Rome, Via A. del Portillo 21, I-00128 Rome, Italy
| | - Stefan Luther
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, D-37077 Göttingen, Germany
| | - Flavio H. Fenton
- School of Physics, Georgia Institute of Technology, 837 State Street Atlanta, Atlanta, GA 30332, USA
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Lujan HL, DiCarlo SE. Cardiac electrophysiology and the susceptibility to sustained ventricular tachycardia in intact, conscious mice. Am J Physiol Heart Circ Physiol 2014; 306:H1213-21. [PMID: 24561859 DOI: 10.1152/ajpheart.00780.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac electrophysiological dysfunction is a major cause of death in humans. Accordingly, electrophysiological testing is routinely performed in intact, conscious, humans to evaluate arrhythmias and disorders of cardiac conduction. However, to date, in vivo electrophysiological studies in mice are limited to anesthetized open-chest or closed-chest preparations. However, cardiac electrophysiology in anesthetized mice or mice with surgical trauma may not adequately represent what occurs in conscious mice. Accordingly, an intact, conscious murine model of cardiac electrophysiology has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of cardiac electrophysiology. The conscious mouse model permits measurements of atrioventricular interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, Wenckebach cycle length, the ventricular effective refractory period (VERP) and the electrical stimulation threshold to induce sustained ventricular tachyarrhythmias in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This is an important consideration because anesthesia and surgical trauma markedly reduced cardiac output and heart rate as well as altered cardiac electrophysiology parameters. Most importantly, anesthesia and surgical trauma significantly increased the VERP and virtually eliminated the ability to induce sustained ventricular tachyarrhythmias. Accordingly, the methodology allows for the accurate documentation of cardiac electrophysiology in complex, conscious mice and may be adopted for advancing the concepts and ideas that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Sayadi O, Merchant FM, Puppala D, Mela T, Singh JP, Heist EK, Owen C, Armoundas AA. A novel method for determining the phase of T-wave alternans: diagnostic and therapeutic implications. Circ Arrhythm Electrophysiol 2013; 6:818-26. [PMID: 23884196 DOI: 10.1161/circep.113.000114] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND T-wave alternans (TWA) has been implicated in the pathogenesis of ventricular arrhythmias and sudden cardiac death. However, to estimate and suppress TWA effectively, the phase of TWA must be accurately determined. METHODS AND RESULTS We developed a method that computes the beat-by-beat integral of the T-wave morphology, over time points within the T-wave with positive alternans. Then, we estimated the signed derivative of the T-wave integral sequence, which allows the classification of each beat to a binary phase index. In animal studies, we found that this method was able to accurately identify the T-wave phase in artificially induced alternans (P<0.0001). The coherence of the phase increased consistently after acute ischemia induction in all body-surface and intracardiac leads (P<0.0001). Also, we developed a phase-resetting detection algorithm that enhances the diagnostic utility of TWA. We further established an algorithm that uses the phase of TWA to deliver appropriate polarity-pacing pulses (all interventions compared with baseline, P<0.0001 for alternans voltage; P<0.0001 for K(score)), to suppress TWA. Finally, we demonstrated that using the phase of TWA we can suppress spontaneous TWA during acute ischemia; 77.6% for alternans voltage (P<0.0001) and 92.5% for K(score) (P<0.0001). CONCLUSIONS We developed a method to quantify the temporal variability of the TWA phase. This method is expected to enhance the utility of TWA in predicting ventricular arrhythmias and sudden cardiac death and raises the possibility of using upstream therapies to abort a ventricular tachyarrhythmia before its onset.
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Kim JJ, Němec J, Papp R, Strongin R, Abramson JJ, Salama G. Bradycardia alters Ca(2+) dynamics enhancing dispersion of repolarization and arrhythmia risk. Am J Physiol Heart Circ Physiol 2013; 304:H848-60. [PMID: 23316064 DOI: 10.1152/ajpheart.00787.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bradycardia prolongs action potential (AP) durations (APD adaptation), enhances dispersion of repolarization (DOR), and promotes tachyarrhythmias. Yet, the mechanisms responsible for enhanced DOR and tachyarrhythmias remain largely unexplored. Ca(2+) transients and APs were measured optically from Langendorff rabbit hearts at high (150 × 150 μm(2)) or low (1.5 × 1.5 cm(2)) magnification while pacing at a physiological (120 beats/min) or a slow heart rate (SHR = 50 beats/min). Western blots and pharmacological interventions were used to elucidate the regional effects of bradycardia. As a result, bradycardia (SHR 50 beats/min) increased APDs gradually (time constant τf→s = 48 ± 9.2 s) and caused a secondary Ca(2+) release (SCR) from the sarcoplasmic reticulum during AP plateaus, occurring at the base on average of 184.4 ± 9.7 ms after the Ca(2+) transient upstroke. In subcellular imaging, SCRs were temporally synchronous and spatially homogeneous within myocytes. In diastole, SHR elicited variable asynchronous sarcoplasmic reticulum Ca(2+) release events leading to subcellular Ca(2+) waves, detectable only at high magnification. SCR was regionally heterogeneous, correlated with APD prolongation (P < 0.01, n = 5), enhanced DOR (r = 0.9277 ± 0.03, n = 7), and was gradually reversed by pacing at 120 beats/min along with APD shortening (P < 0.05, n = 5). A stabilizer of leaky ryanodine receptors (RyR2), 3-(4-benzylcyclohexyl)-1-(7-methoxy-2,3-dihydrobenzo[f][1,4]thiazepin-4(5H)-yl)propan-1-one (K201; 1 μM), suppressed SCR and reduced APD at the base, thereby reducing DOR (P < 0.02, n = 5). Ventricular ectopy induced by bradycardia (n = 5/15) was suppressed by K201. Western blot analysis revealed spatial differences of voltage-gated L-type Ca(2+) channel protein (Cav1.2α), Na(+)-Ca(2+) exchange (NCX1), voltage-gated Na(+) channel (Nav1.5), and rabbit ether-a-go-go-related (rERG) protein [but not RyR2 or sarcoplasmic reticulum Ca(2+) ATPase 2a] that correlate with the SCR distribution and explain the molecular basis for SCR heterogeneities. In conclusion, acute bradycardia elicits synchronized subcellular SCRs of sufficient magnitude to overcome the source-sink mismatch and to promote afterdepolarizations.
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Affiliation(s)
- Jong J Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Total beta-adrenoceptor knockout slows conduction and reduces inducible arrhythmias in the mouse heart. PLoS One 2012; 7:e49203. [PMID: 23133676 PMCID: PMC3486811 DOI: 10.1371/journal.pone.0049203] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/05/2012] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Beta-adrenoceptors (β-AR) play an important role in the neurohumoral regulation of cardiac function. Three β-AR subtypes (β(1), β(2), β(3)) have been described so far. Total deficiency of these adrenoceptors (TKO) results in cardiac hypotrophy and negative inotropy. TKO represents a unique mouse model mimicking total unselective medical β-blocker therapy in men. Electrophysiological characteristics of TKO have not yet been investigated in an animal model. METHODS In vivo electrophysiological studies using right heart catheterisation were performed in 10 TKO mice and 10 129SV wild type control mice (WT) at the age of 15 weeks. Standard surface ECG, intracardiac and electrophysiological parameters, and arrhythmia inducibility were analyzed. RESULTS The surface ECG of TKO mice revealed a reduced heart rate (359.2±20.9 bpm vs. 461.1±33.3 bpm; p<0.001), prolonged P wave (17.5±3.0 ms vs. 15.1±1.2 ms; p = 0.019) and PQ time (40.8±2.4 ms vs. 37.3±3.0 ms; p = 0.013) compared to WT. Intracardiac ECG showed a significantly prolonged infra-Hisian conductance (HV-interval: 12.9±1.4 ms vs. 6.8±1.0 ms; p<0.001). Functional testing showed prolonged atrial and ventricular refractory periods in TKO (40.5±15.5 ms vs. 21.3±5.8 ms; p = 0.004; and 41.0±9.7 ms vs. 28.3±6.6 ms; p = 0.004, respectively). In TKO both the probability of induction of atrial fibrillation (12% vs. 24%; p<0.001) and of ventricular tachycardias (0% vs. 26%; p<0.001) were significantly reduced. CONCLUSION TKO results in significant prolongations of cardiac conduction times and refractory periods. This was accompanied by a highly significant reduction of atrial and ventricular arrhythmias. Our finding confirms the importance of β-AR in arrhythmogenesis and the potential role of unspecific beta-receptor-blockade as therapeutic target.
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Land S, Niederer SA, Aronsen JM, Espe EKS, Zhang L, Louch WE, Sjaastad I, Sejersted OM, Smith NP. An analysis of deformation-dependent electromechanical coupling in the mouse heart. J Physiol 2012; 590:4553-69. [PMID: 22615436 PMCID: PMC3477757 DOI: 10.1113/jphysiol.2012.231928] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 05/17/2012] [Indexed: 01/20/2023] Open
Abstract
To investigate the effects of the coupling between excitation and contraction on whole-organ function, we have developed a novel biophysically based multiscale electromechanical model of the murine heart. Through comparison with a comprehensive in vivo experimental data set, we show good agreement with pressure and volume measurements at both physiological temperatures and physiological pacing frequencies. This whole-organ model was used to investigate the effects of material and haemodynamic properties introduced at the tissue level, as well as emergent function of our novel cell contraction model. Through a comprehensive sensitivity analysis at both the cellular and whole organ level, we demonstrate the sensitivity of the model's results to its parameters and the constraining effect of experimental data. These results demonstrate the fundamental importance of length- and velocity-dependent feedback to the cellular scale for whole-organ function, and we show that a strong velocity dependence of tension is essential for explaining the differences between measured single cell tension and whole-organ pressure transients.
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Affiliation(s)
- Sander Land
- Department of Computer Science, University of Oxford, Oxford, UK
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Askar SFA, Bingen BO, Schalij MJ, Swildens J, Atsma DE, Schutte CI, de Vries AAF, Zeppenfeld K, Ypey DL, Pijnappels DA. Similar arrhythmicity in hypertrophic and fibrotic cardiac cultures caused by distinct substrate-specific mechanisms. Cardiovasc Res 2012; 97:171-81. [PMID: 22977008 DOI: 10.1093/cvr/cvs290] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Cardiac hypertrophy and fibrosis are associated with potentially lethal arrhythmias. As these substrates often occur simultaneously in one patient, distinguishing between pro-arrhythmic mechanisms is difficult. This hampers understanding of underlying pro-arrhythmic mechanisms and optimal treatment. This study investigates and compares arrhythmogeneity and underlying pro-arrhythmic mechanisms of either cardiac hypertrophy or fibrosis in in vitro models. METHODS AND RESULTS Fibrosis was mimicked by free myofibroblast (MFB) proliferation in neonatal rat ventricular monolayers. Cultures with inhibited MFB proliferation were used as control or exposed to phenylephrine to induce hypertrophy. At Day 9, cultures were studied with patch-clamp and optical-mapping techniques and assessed for protein expression. In hypertrophic (n = 111) and fibrotic cultures (n = 107), conduction and repolarization were slowed. Triggered activity was commonly found in these substrates and led to high incidences of spontaneous re-entrant arrhythmias [67.5% hypertrophic, 78.5% fibrotic vs. 2.9% in controls (n = 102)] or focal arrhythmias (39.1, 51.7 vs. 8.8%, respectively). Kv4.3 and Cx43 protein expression levels were decreased in hypertrophy but unaffected in fibrosis. Depolarization of cardiomyocytes (CMCs) was only found in fibrotic cultures (-48 ± 7 vs. -66 ± 7 mV in control, P < 0.001). L-type calcium-channel blockade prevented arrhythmias in hypertrophy, but caused conduction block in fibrosis. Targeting heterocellular coupling by low doses of gap-junction uncouplers prevented arrhythmias by accelerating repolarization only in fibrotic cultures. CONCLUSION Cultured hypertrophic or fibrotic myocardial tissues generated similar focal and re-entrant arrhythmias. These models revealed electrical remodelling of CMCs as a pro-arrhythmic mechanism of hypertrophy and MFB-induced depolarization of CMCs as a pro-arrhythmic mechanism of fibrosis. These findings provide novel mechanistic insight into substrate-specific arrhythmicity.
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Affiliation(s)
- Saïd F A Askar
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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Brines L, Such-Miquel L, Gallego D, Trapero I, del Canto I, Zarzoso M, Soler C, Pelechano F, Cánoves J, Alberola A, Such L, Chorro FJ. Modifications of mechanoelectric feedback induced by 2,3-butanedione monoxime and Blebbistatin in Langendorff-perfused rabbit hearts. Acta Physiol (Oxf) 2012; 206:29-41. [PMID: 22497862 DOI: 10.1111/j.1748-1716.2012.02441.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/16/2011] [Accepted: 03/26/2012] [Indexed: 11/30/2022]
Abstract
AIM Myocardial stretching is an arrhythmogenic factor. Optical techniques and mechanical uncouplers are used to study the mechanoelectric feedback. The aim of this study is to determine whether the mechanical uncouplers 2,3-butanedione monoxime and Blebbistatin hinder or modify the electrophysiological effects of acute mechanical stretch. METHODS The ventricular fibrillation (VF) modifications induced by acute mechanical stretch were studied in 27 Langendorff-perfused rabbit hearts using epicardial multiple electrodes and mapping techniques under control conditions (n = 9) and during the perfusion of 2,3-butanedione monoxime (15 mM) (n = 9) or Blebbistatin (10 μm) (n = 9). RESULTS In the control series, myocardial stretch increased the complexity of the activation maps and the dominant frequency (DF) of VF from 13.1 ± 2.0 Hz to 19.1 ± 3.1 Hz (P < 0.001, 46% increment). At baseline, the activation maps showed less complexity in both the 2,3-butanedione monoxime and Blebbistatin series, and the DF was lower in the 2,3-butanedione monoxime series (11.4 ± 1.2 Hz; P < 0.05). The accelerating effect of mechanical stretch was abolished under 2,3-butanedione monoxime (maximum DF = 11.7 ± 2.4 Hz, 5% increment, ns vs baseline, P < 0.0001 vs. control series) and reduced under Blebbistatin (maximum DF = 12.9 ± 0.7 Hz, 8% increment, P < 0.01 vs. baseline, P < 0.0001 vs. control series). The variations in complexity of the activation maps under stretch were not significant in the 2,3-butanedione monoxime series and were significantly attenuated under Blebbistatin. CONCLUSION The accelerating effect and increased complexity of myocardial activation during VF induced by acute mechanical stretch are abolished under the action of 2,3-butanedione monoxime and reduced under the action of Blebbistatin.
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Affiliation(s)
- L. Brines
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - L. Such-Miquel
- Department of Physiotherapy; Valencia University, Estudi General; Valencia; Spain
| | - D. Gallego
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - I. Trapero
- Department of Infirmary; Valencia University, Estudi General; Valencia; Spain
| | - I. del Canto
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - M. Zarzoso
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - C. Soler
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - F. Pelechano
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - J. Cánoves
- Service of Cardiology; Valencia University Clinic Hospital; INCLIVA, Valencia; Spain
| | - A. Alberola
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - L. Such
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
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Tao W, Shi J, Dorn GW, Wei L, Rubart M. Spatial variability in T-tubule and electrical remodeling of left ventricular epicardium in mouse hearts with transgenic Gαq overexpression-induced pathological hypertrophy. J Mol Cell Cardiol 2012; 53:409-19. [PMID: 22728217 DOI: 10.1016/j.yjmcc.2012.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 05/18/2012] [Accepted: 06/13/2012] [Indexed: 10/28/2022]
Abstract
Pathological left ventricular hypertrophy (LVH) is consistently associated with prolongation of the ventricular action potentials. A number of previous studies, employing various experimental models of hypertrophy, have revealed marked differences in the effects of hypertrophy on action potential duration (APD) between myocytes from endocardial and epicardial layers of the LV free wall. It is not known, however, whether pathological LVH is also accompanied by redistribution of APD among myocytes from the same layer in the LV free wall. In the experiments here, LV epicardial action potential remodeling was examined in a mouse model of decompensated LVH, produced by cardiac-restricted transgenic Gαq overexpression. Confocal linescanning-based optical recordings of propagated action potentials from individual in situ cardiomyocytes across the outer layer of the anterior LV epicardium demonstrated spatially non-uniform action potential prolongation in transgenic hearts, giving rise to alterations in spatial dispersion of epicardial repolarization. Local density and distribution of anti-Cx43 mmune reactivity in Gαq hearts were unchanged compared to wild-type hearts, suggesting preservation of intercellular coupling. Confocal microscopy also revealed heterogeneous disorganization of T-tubules in epicardial cardiomyocytes in situ. These data provide evidence of the existence of significant electrical and structural heterogeneity within the LV epicardial layer of hearts with transgenic Gαq overexpression-induced hypertrophy, and further support the notion that a small portion of electrically well connected LV tissue can maintain dispersion of action potential duration through heterogeneity in the activities of sarcolemmal ionic currents that control repolarization. It remains to be examined whether other experimental models of pathological LVH, including pressure overload LVH, similarly exhibit alterations in T-tubule organization and/or dispersion of repolarization within distinct layers of LV myocardium.
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Affiliation(s)
- Wen Tao
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202-5225, USA
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Liao R, Podesser BK, Lim CC. The continuing evolution of the Langendorff and ejecting murine heart: new advances in cardiac phenotyping. Am J Physiol Heart Circ Physiol 2012; 303:H156-67. [PMID: 22636675 DOI: 10.1152/ajpheart.00333.2012] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The isolated retrograde-perfused Langendorff heart and the isolated ejecting heart have, over many decades, resulted in fundamental discoveries that form the underpinnings of our current understanding of the biology and physiology of the heart. These two experimental methodologies have proven invaluable in studying pharmacological effects on myocardial function, metabolism, and vascular reactivity and in the investigation of clinically relevant disease states such as ischemia-reperfusion injury, diabetes, obesity, and heart failure. With the advent of the genomics era, the isolated mouse heart preparation has gained prominence as an ex vivo research tool for investigators studying the impact of gene modification in the intact heart. This review summarizes the historical development of the isolated heart and provides a practical guide for the establishment of the Langendorff and ejecting heart preparations with a particular emphasis on the murine heart. In addition, current applications and novel methods of recording cardiovascular parameters in the isolated heart preparation will be discussed. With continued advances in methodological recordings, the isolated mouse heart preparation will remain physiologically relevant for the foreseeable future, serving as an integral bridge between in vitro assays and in vivo approaches.
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Affiliation(s)
- Ronglih Liao
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
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Suzuki T, Shioya T, Murayama T, Sugihara M, Odagiri F, Nakazato Y, Nishizawa H, Chugun A, Sakurai T, Daida H, Morimoto S, Kurebayashi N. Multistep ion channel remodeling and lethal arrhythmia precede heart failure in a mouse model of inherited dilated cardiomyopathy. PLoS One 2012; 7:e35353. [PMID: 22514734 PMCID: PMC3325934 DOI: 10.1371/journal.pone.0035353] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 03/14/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Patients with inherited dilated cardiomyopathy (DCM) frequently die with severe heart failure (HF) or die suddenly with arrhythmias, although these symptoms are not always observed at birth. It remains unclear how and when HF and arrhythmogenic changes develop in these DCM mutation carriers. In order to address this issue, properties of the myocardium and underlying gene expressions were studied using a knock-in mouse model of human inherited DCM caused by a deletion mutation ΔK210 in cardiac troponinT. METHODOLOGY/PRINCIPAL FINDINGS By 1 month, DCM mice had already enlarged hearts, but showed no symptoms of HF and a much lower mortality than at 2 months or later. At around 2 months, some would die suddenly with no clear symptoms of HF, whereas at 3 months, many of the survivors showed evident symptoms of HF. In isolated left ventricular myocardium (LV) from 2 month-mice, spontaneous activity frequently occurred and action potential duration (APD) was prolonged. Transient outward (I(to)) and ultrarapid delayed rectifier K(+) (I(Kur)) currents were significantly reduced in DCM myocytes. Correspondingly, down-regulation of Kv4.2, Kv1.5 and KChIP2 was evident in mRNA and protein levels. In LVs at 3-months, more frequent spontaneous activity, greater prolongation of APD and further down-regulation in above K(+) channels were observed. At 1 month, in contrast, infrequent spontaneous activity and down-regulation of Kv4.2, but not Kv1.5 or KChIP2, were observed. CONCLUSIONS/SIGNIFICANCE Our results suggest that at least three steps of electrical remodeling occur in the hearts of DCM model mice, and that the combined down-regulation of Kv4.2, Kv1.5 and KChIP2 prior to the onset of HF may play an important role in the premature sudden death in this DCM model. DCM mice at 1 month or before, on the contrary, are associated with low risk of death in spite of inborn disorder and enlarged heart.
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Affiliation(s)
- Takeshi Suzuki
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takao Shioya
- Department of Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Takashi Murayama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Masami Sugihara
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Fuminori Odagiri
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yuji Nakazato
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroto Nishizawa
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Akihito Chugun
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroyuki Daida
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Sachio Morimoto
- Department of Clinical Pharmacology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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Ferreiro M, Petrosky AD, Escobar AL. Intracellular Ca2+ release underlies the development of phase 2 in mouse ventricular action potentials. Am J Physiol Heart Circ Physiol 2011; 302:H1160-72. [PMID: 22198177 DOI: 10.1152/ajpheart.00524.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ventricular action potential (AP) is characterized by a fast depolarizing phase followed by a repolarization that displays a second upstroke known as phase 2. This phase is generally not present in mouse ventricular myocytes. Thus we performed colocalized electrophysiological and optical recordings of APs in Langendorff-perfused mouse hearts founding a noticeable phase 2. Ryanodine as well as nifedipine reduced phase 2. Our hypothesis is that a depolarizing current activated by Ca(2+) released from the sarcoplasmic reticulum (SR) rather than the "electrogenicity" of the L-type Ca(2+) current is crucial in the generation of mouse ventricular phase 2. When Na(+) was partially replaced by Li(+) in the extracellular perfusate or the organ was cooled down, phase 2 was reduced. These results suggest that the Na(+)/Ca(2+) exchanger functioning in the forward mode is driving the depolarizing current that defines phase 2. Phase 2 appears to be an intrinsic characteristic of single isolated myocytes and not an emergent property of the tissue. As in whole heart experiments, ventricular myocytes impaled with microelectrodes displayed a large phase 2 that significantly increases when temperature was raised from 22 to 37°C. We conclude that mouse ventricular APs display a phase 2; however, changes in Ca(2+) dynamics and thermodynamic parameters also diminish phase 2, mostly by impairing the Na(+)/Ca(2+) exchanger. In summary, these results provide important insights about the role of Ca(2+) release in AP ventricular repolarization under physiological and pathological conditions.
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Affiliation(s)
- Marcela Ferreiro
- Biological Engineering and Small Scale Technologies Program, School of Engineering, University of California, Merced, CA 95343, USA
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45
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Petkova-Kirova PS, London B, Salama G, Rasmusson RL, Bondarenko VE. Mathematical modeling mechanisms of arrhythmias in transgenic mouse heart overexpressing TNF-α. Am J Physiol Heart Circ Physiol 2011; 302:H934-52. [PMID: 22081697 DOI: 10.1152/ajpheart.00493.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transgenic mice overexpressing tumor necrosis factor-α (TNF-α mice) possess many of the features of human heart failure, such as dilated cardiomyopathy, impaired Ca(2+) handling, arrhythmias, and decreased survival. Although TNF-α mice have been studied extensively with a number of experimental methods, the mechanisms of heart failure are not completely understood. We created a mathematical model that reproduced experimentally observed changes in the action potential (AP) and Ca(2+) handling of isolated TNF-α mice ventricular myocytes. To study the contribution of the differences in ion currents, AP, Ca(2+) handling, and intercellular coupling to the development of arrhythmias in TNF-α mice, we further created several multicellular model tissues with combinations of wild-type (WT)/reduced gap junction conductance, WT/prolonged AP, and WT/decreased Na(+) current (I(Na)) amplitude. All model tissues were examined for susceptibility to Ca(2+) alternans, AP propagation block, and reentry. Our modeling results demonstrated that, similar to experimental data in TNF-α mice, Ca(2+) alternans in TNF-α tissues developed at longer basic cycle lengths. The greater susceptibility to Ca(2+) alternans was attributed to the prolonged AP, resulting in larger inactivation of I(Na), and to the decreased SR Ca(2+) uptake and corresponding smaller SR Ca(2+) load. Simulations demonstrated that AP prolongation induces an increased susceptibility to AP propagation block. Programmed stimulation of the model tissues with a premature impulse showed that reduced gap junction conduction increased the vulnerable window for initiation reentry, supporting the idea that reduced intercellular coupling is the major factor for reentrant arrhythmias in TNF-α mice.
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Affiliation(s)
- Polina S Petkova-Kirova
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Lang D, Sulkin M, Lou Q, Efimov IR. Optical mapping of action potentials and calcium transients in the mouse heart. J Vis Exp 2011:3275. [PMID: 21946907 PMCID: PMC3230201 DOI: 10.3791/3275] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The mouse heart is a popular model for cardiovascular studies due to the existence of low cost technology for genetic engineering in this species. Cardiovascular physiological phenotyping of the mouse heart can be easily done using fluorescence imaging employing various probes for transmembrane potential (Vm), calcium transients (CaT), and other parameters. Excitation-contraction coupling is characterized by action potential and intracellular calcium dynamics; therefore, it is critically important to map both Vm and CaT simultaneously from the same location on the heart1-4. Simultaneous optical mapping from Langendorff perfused mouse hearts has the potential to elucidate mechanisms underlying heart failure, arrhythmias, metabolic disease, and other heart diseases. Visualization of activation, conduction velocity, action potential duration, and other parameters at a myriad of sites cannot be achieved from cellular level investigation but is well solved by optical mapping1,5,6. In this paper we present the instrumentation setup and experimental conditions for simultaneous optical mapping of Vm and CaT in mouse hearts with high spatio-temporal resolution using state-of-the-art CMOS imaging technology. Consistent optical recordings obtained with this method illustrate that simultaneous optical mapping of Langendorff perfused mouse hearts is both feasible and reliable.
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Affiliation(s)
- Di Lang
- Department of Biomedical Engineering, Washington University in St. Louis, USA
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Martin CA, Grace AA, Huang CLH. Refractory dispersion promotes conduction disturbance and arrhythmias in a Scn5a (+/-) mouse model. Pflugers Arch 2011; 462:495-504. [PMID: 21779762 PMCID: PMC3170477 DOI: 10.1007/s00424-011-0989-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 06/10/2011] [Accepted: 06/15/2011] [Indexed: 11/29/2022]
Abstract
Accentuated right ventricular (RV) gradients in action potential duration (APD) have been implicated in the arrhythmogenicity observed in Brugada syndrome in studies assuming that ventricular effective refractory periods (VERPs) vary in concert with APDs. The present experiments use a genetically modified mouse model to explore spatial heterogeneities in VERP that in turn might affect conduction velocity, thereby causing arrhythmias. Activation latencies, APDs and VERPs recorded during programmed S1S2 protocols were compared in RV and left ventricular (LV) epicardia and endocardia of Langendorff-perfused wild-type (WT) and Scn5a+/− hearts. Scn5a+/− and WT hearts showed similar patterns of shorter VERPs in RV than LV epicardia, and in epicardia than endocardia. However, Scn5a+/− hearts showed longer VERPs, despite shorter APD90s, than WT in all regions examined. The pro- and anti-arrhythmic agents flecainide and quinidine increased regional VERPs despite respectively decreasing and increasing the corresponding APD90s particularly in Scn5a+/− RV epicardia. In contrast, Scn5a+/− hearts showed greater VERP gradients between neighbouring regions, particularly RV transmural gradients, than WT (9.1 ± 1.1 vs. 5.7 ± 0.5 ms, p < 0.05, n = 12). Flecainide increased (to 21 ± 0.9 ms, p < 0.05, n = 6) but quinidine decreased (to 4.5 ± 0.5 ms, p < 0.05, n = 6) these gradients, particularly across the Scn5a+/− RV. Finally, Scn5a+/− hearts showed greater conduction slowing than WT following S2 stimuli, particularly with flecainide administration. Rather than arrhythmogenesis resulting from increased transmural repolarization gradients in an early, phase 2, reentrant excitation mechanism, the present findings implicate RV VERP gradients in potential reentrant mechanisms involving impulse conduction slowed by partial refractoriness.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge, CB2 3EG, UK.
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Weiss EH, Merchant FM, d'Avila A, Foley L, Reddy VY, Singh JP, Mela T, Ruskin JN, Armoundas AA. A novel lead configuration for optimal spatio-temporal detection of intracardiac repolarization alternans. Circ Arrhythm Electrophysiol 2011; 4:407-17. [PMID: 21430127 DOI: 10.1161/circep.109.934208] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Electric alternans is a pattern of variation in the shape of ECG waveform that occurs every other beat. In humans, alternation in ventricular repolarization, known as repolarization alternans (RA), has been associated with increased vulnerability to ventricular tachycardia/fibrillation and sudden cardiac death. METHODS AND RESULTS This study investigates the spatio-temporal variability of intracardiac RA and its relationship to body surface RA in an acute myocardial ischemia model in swine. We developed a real-time multichannel repolarization signal acquisition, display, and analysis system to record ECG signals from catheters in the right ventricle, coronary sinus, left ventricle, and epicardial surface before and after circumflex coronary artery balloon occlusion. We found that RA is detectable within 4 minutes after the onset ischemia and is most prominently seen during the first half of the repolarization interval. Ischemia-induced RA was detectable on unipolar and bipolar leads (both in near- and far-field configurations) and on body surface leads. Far-field bipolar intracardiac leads were more sensitive for RA detection than body surface leads, with the probability of body surface RA detection increasing as the number of intracardiac leads detecting RA increased, approaching 100% when at least three intracardiac leads detected RA. We developed a novel, clinically applicable intracardiac lead system based on a triangular arrangement of leads spanning the right ventricular and coronary sinus catheters, which provided the highest sensitivity for intracardiac RA detection when compared with any other far-field bipolar sensing configurations. CONCLUSIONS In conclusion, intracardiac alternans, a complex spatio-temporal phenomenon associated with arrhythmia susceptibility and sudden cardiac death, can be reliably detected through a novel triangular right ventricular-coronary sinus lead configuration.
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Affiliation(s)
- Eric H Weiss
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, USA
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Salama G, Akar FG. Deciphering Arrhythmia Mechanisms - Tools of the Trade. Card Electrophysiol Clin 2011; 3:11-21. [PMID: 21572551 PMCID: PMC3093299 DOI: 10.1016/j.ccep.2010.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Pathophysiological remodeling of cardiac function occurs at multiple levels, spanning the spectrum from molecular and sub-cellular changes to those occurring at the organ-system levels. Of key importance to arrhythmias are changes in electrophysiological and calcium handling properties at the tissue level. In this review, we discuss how high-resolution optical action potential and calcium transient imaging has advanced our understanding of basic arrhythmia mechanisms associated with multiple cardiovascular disorders, including the long QT syndrome, heart failure, and ischemia-reperfusion injury. We focus on the role of repolarization gradients (section 1) and calcium mediated triggers (section 2) in the initiation and maintenance of complex arrhythmias in these settings.
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Affiliation(s)
- Guy Salama
- University of Pittsburgh, The Cardiovascular Institute, Pittsburgh, PA, 15261
| | - Fadi G. Akar
- Mount Sinai School of Medicine, New York, NY 10029, Tel: 212-241-9251; FAX: 212-241-4080
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50
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Nerbonne JM. Molecular Analysis of Voltage‐Gated K
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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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