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Rieder M, Kreifels P, Stuplich J, Ziupa D, Servatius H, Nicolai L, Castiglione A, Zweier C, Asatryan B, Odening KE. Genotype-Specific ECG-Based Risk Stratification Approaches in Patients With Long-QT Syndrome. Front Cardiovasc Med 2022; 9:916036. [PMID: 35911527 PMCID: PMC9329832 DOI: 10.3389/fcvm.2022.916036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Background Congenital long-QT syndrome (LQTS) is a major cause of sudden cardiac death (SCD) in young individuals, calling for sophisticated risk assessment. Risk stratification, however, is challenging as the individual arrhythmic risk varies pronouncedly, even in individuals carrying the same variant. Materials and Methods In this study, we aimed to assess the association of different electrical parameters with the genotype and the symptoms in patients with LQTS. In addition to the heart-rate corrected QT interval (QTc), markers for regional electrical heterogeneity, such as QT dispersion (QTmax-QTmin in all ECG leads) and delta Tpeak/end (Tpeak/end V5 – Tpeak/end V2), were assessed in the 12-lead ECG at rest and during exercise testing. Results QTc at rest was significantly longer in symptomatic than asymptomatic patients with LQT2 (493.4 ms ± 46.5 ms vs. 419.5 ms ± 28.6 ms, p = 0.004), but surprisingly not associated with symptoms in LQT1. In contrast, post-exercise QTc (minute 4 of recovery) was significantly longer in symptomatic than asymptomatic patients with LQT1 (486.5 ms ± 7.0 ms vs. 463.3 ms ± 16.3 ms, p = 0.04), while no such difference was observed in patients with LQT2. Enhanced delta Tpeak/end and QT dispersion were only associated with symptoms in LQT1 (delta Tpeak/end 19.0 ms ± 18.1 ms vs. −4.0 ms ± 4.4 ms, p = 0.02; QT-dispersion: 54.3 ms ± 10.2 ms vs. 31.4 ms ± 10.4 ms, p = 0.01), but not in LQT2. Delta Tpeak/end was particularly discriminative after exercise, where all symptomatic patients with LQT1 had positive and all asymptomatic LQT1 patients had negative values (11.8 ± 7.9 ms vs. −7.5 ± 1.7 ms, p = 0.003). Conclusion Different electrical parameters can distinguish between symptomatic and asymptomatic patients in different genetic forms of LQTS. While the classical “QTc at rest” was only associated with symptoms in LQT2, post-exercise QTc helped distinguish between symptomatic and asymptomatic patients with LQT1. Enhanced regional electrical heterogeneity was only associated with symptoms in LQT1, but not in LQT2. Our findings indicate that genotype-specific risk stratification approaches based on electrical parameters could help to optimize risk assessment in LQTS.
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Affiliation(s)
- Marina Rieder
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Paul Kreifels
- Department of Cardiology and Angiology I, Faculty of Medicine, University Heart Center Freiburg-Bad Krozingen, University of Freiburg, Freiburg, Germany
| | - Judith Stuplich
- Department of Cardiology and Angiology I, Faculty of Medicine, University Heart Center Freiburg-Bad Krozingen, University of Freiburg, Freiburg, Germany
| | - David Ziupa
- Department of Cardiology and Angiology I, Faculty of Medicine, University Heart Center Freiburg-Bad Krozingen, University of Freiburg, Freiburg, Germany
| | - Helge Servatius
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Luisa Nicolai
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Alessandro Castiglione
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Christiane Zweier
- Department of Human Genetics, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Babken Asatryan
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Katja E Odening
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
- Department of Physiology, University of Bern, Bern, Switzerland
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2
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Odening KE, van der Linde HJ, Ackerman MJ, Volders PGA, ter Bekke RMA. OUP accepted manuscript. Eur Heart J 2022; 43:3018-3028. [PMID: 35445703 PMCID: PMC9443984 DOI: 10.1093/eurheartj/ehac135] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 02/23/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation–contraction coupling. However, the mutual influencing of excitation–contraction and mechano-electrical feedback in the beating heart, here designated ‘electromechanical reciprocity’, remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed—by volume loading during the rapid filling phase—when repolarization is still ongoing. This creates a ‘sensitized’ electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.
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Affiliation(s)
| | - Henk J van der Linde
- Janssen Research & Development, Division of Janssen Pharmaceutica N.V., Beerse, Belgium
| | - Michael J Ackerman
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN, USA
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center+, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
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3
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Müllenbroich MC, Kelly A, Acker C, Bub G, Bruegmann T, Di Bona A, Entcheva E, Ferrantini C, Kohl P, Lehnart SE, Mongillo M, Parmeggiani C, Richter C, Sasse P, Zaglia T, Sacconi L, Smith GL. Novel Optics-Based Approaches for Cardiac Electrophysiology: A Review. Front Physiol 2021; 12:769586. [PMID: 34867476 PMCID: PMC8637189 DOI: 10.3389/fphys.2021.769586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/18/2021] [Indexed: 12/31/2022] Open
Abstract
Optical techniques for recording and manipulating cellular electrophysiology have advanced rapidly in just a few decades. These developments allow for the analysis of cardiac cellular dynamics at multiple scales while largely overcoming the drawbacks associated with the use of electrodes. The recent advent of optogenetics opens up new possibilities for regional and tissue-level electrophysiological control and hold promise for future novel clinical applications. This article, which emerged from the international NOTICE workshop in 2018, reviews the state-of-the-art optical techniques used for cardiac electrophysiological research and the underlying biophysics. The design and performance of optical reporters and optogenetic actuators are reviewed along with limitations of current probes. The physics of light interaction with cardiac tissue is detailed and associated challenges with the use of optical sensors and actuators are presented. Case studies include the use of fluorescence recovery after photobleaching and super-resolution microscopy to explore the micro-structure of cardiac cells and a review of two photon and light sheet technologies applied to cardiac tissue. The emergence of cardiac optogenetics is reviewed and the current work exploring the potential clinical use of optogenetics is also described. Approaches which combine optogenetic manipulation and optical voltage measurement are discussed, in terms of platforms that allow real-time manipulation of whole heart electrophysiology in open and closed-loop systems to study optimal ways to terminate spiral arrhythmias. The design and operation of optics-based approaches that allow high-throughput cardiac electrophysiological assays is presented. Finally, emerging techniques of photo-acoustic imaging and stress sensors are described along with strategies for future development and establishment of these techniques in mainstream electrophysiological research.
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Affiliation(s)
| | - Allen Kelly
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Corey Acker
- Center for Cell Analysis and Modeling, UConn Health, Farmington, CT, United States
| | - Gil Bub
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Tobias Bruegmann
- Institute for Cardiovascular Physiology, University Medical Center Goettingen, Goettingen, Germany
| | - Anna Di Bona
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy
| | - Emilia Entcheva
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | | | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Stephan E. Lehnart
- Heart Research Center Göttingen, University Medical Center Göttingen, Göttingen, Germany
- Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | | | - Claudia Richter
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Leonardo Sacconi
- European Laboratory for Nonlinear Spectroscopy, Sesto Fiorentino, Italy
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
- National Institute of Optics, National Research Council, Florence, Italy
| | - Godfrey L. Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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4
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Crotti L, Odening KE, Sanguinetti MC. Heritable arrhythmias associated with abnormal function of cardiac potassium channels. Cardiovasc Res 2021; 116:1542-1556. [PMID: 32227190 DOI: 10.1093/cvr/cvaa068] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/24/2020] [Accepted: 03/26/2020] [Indexed: 12/16/2022] Open
Abstract
Cardiomyocytes express a surprisingly large number of potassium channel types. The primary physiological functions of the currents conducted by these channels are to maintain the resting membrane potential and mediate action potential repolarization under basal conditions and in response to changes in the concentrations of intracellular sodium, calcium, and ATP/ADP. Here, we review the diversity and functional roles of cardiac potassium channels under normal conditions and how heritable mutations in the genes encoding these channels can lead to distinct arrhythmias. We briefly review atrial fibrillation and J-wave syndromes. For long and short QT syndromes, we describe their genetic basis, clinical manifestation, risk stratification, traditional and novel therapeutic approaches, as well as insights into disease mechanisms provided by animal and cellular models.
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Affiliation(s)
- Lia Crotti
- Center for Cardiac Arrhythmias of Genetic Origin, Istituto Auxologico Italiano, IRCCS, Milan, Italy.,Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy.,Department of Cardiovascular, Neural and Metabolic Sciences, Istituto Auxologico Italiano, IRCCS, San Luca Hospital, Milan, Italy.,Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Institute of Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Medical Faculty, Freiburg, Germany.,Department of Cardiology, Translational Cardiology, Inselspital, Bern University Hospital, and Institute of Physiology, University of Bern, Bern, Switzerland
| | - Michael C Sanguinetti
- Department of Internal Medicine, Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
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5
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Gutierrez G, Wamboldt R, Baranchuk A. The Impact of Testosterone on the QT Interval: A Systematic Review. Curr Probl Cardiol 2021; 47:100882. [PMID: 34103195 DOI: 10.1016/j.cpcardiol.2021.100882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 11/03/2022]
Abstract
Humans and mammals have sex-specific differences in cardiac electrophysiology, linked to the action of sex hormones in the cardiac muscle. These hormones can upregulate or downregulate the expression of ionic channels modulating the cardiac cycle through genomic and non-genomic interactions. Systematic search in PubMed, Medline and EMBASE including keywords pertaining to testosterone and QT interval. Included experimental studies and observation studies and case reports presenting the results of testosterone administration, excess or deficiency in humans and animals. Testosterone has been shown to shorten the action potential duration, by enhancing the expression of K+ channels and downregulating ICaL increasing the repolarization reserve of the cardiac muscle. This effect has been observed in both genders and animals. Testosterone deficient states can promote arrhythmogenesis. The evidence in this paper may be used to guide clinical considerations, such as increased clinical surveillance of patients in testosterone deficient states using ECG.
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Affiliation(s)
- Gilmar Gutierrez
- Faculty of Health Sciences, School of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Rachel Wamboldt
- Division of Internal Medicine, Kingston Health Science Center, Queen's University, Kingston, Ontario, Canada
| | - Adrian Baranchuk
- Division of Cardiology, Kingston Health Science Center, Queen's University, Kingston, Ontario, Canada.
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6
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Himel HD, Cupelli M, Boutjdir M, El-Sherif N. Voltage/Calcium Uncoupling Underlies Sustained Torsade de Pointes Ventricular Tachyarrhythmia in an Experimental Model of Long QT Syndrome. Front Physiol 2021; 12:617847. [PMID: 33584347 PMCID: PMC7876465 DOI: 10.3389/fphys.2021.617847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/12/2021] [Indexed: 11/23/2022] Open
Abstract
Background Clinical experience showed that the majority of Torsade de Pointes (TdP) ventricular tachyarrhythmia (VT) in patients with long QT syndrome (LQTS) are self-terminating (ST), but the few that are non-self-terminating (NST) are potentially fatal. A paramount issue in clinical arrhythmology is to understand the electrophysiological mechanism of ST vs. NST TdP VT. Methods We investigated the electrophysiological mechanism of ST vs. NST TdP VT in the guinea pig Anthopleurin-A experimental model of LQTS, a close surrogate model of congenital LQT3. We utilized simultaneous optical recordings of membrane voltage (Vm) and intracellular calcium (Cai) and a robust analytical method based on spatiotemporal entropy difference (Ed) to investigate the hypothesis that early Vm/Cai uncoupling during TdP VT can play a primary role in perpetuation of VT episodes. Results We analyzed a total of 35 episodes of TdP VT from 14 guinea pig surrogate models of LQTS, including 23 ST and 12 NST VTs. Ed values for NST VT were significantly higher than Ed values for ST VT. Analysis of wave front topology during the early phase of ST VT showed the Cai wave front following closely Vm wave front consistent with a lower degree of Ed. In contrast, NST VT was associated with uncoupling of Vm/Cai wave fronts during the first 2 or 3 cycles of VT associated with early wave break propagation pattern. Conclusions Utilizing a robust analytical method we showed that, in comparison to ST TdP VT, NST VT was consistently predated by early uncoupling of Vm/Cai that destabilized wave front propagation and can explain a sustained complex reentrant excitation pattern.
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Affiliation(s)
- Herman D Himel
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States
| | - Michael Cupelli
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States
| | - Mohamed Boutjdir
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States.,School of Medicine, New York University, New York, NY, United States
| | - Nabil El-Sherif
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States
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7
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Borowiec K, Kowalski M, Kumor M, Duliban J, Śmigielski W, Hoffman P, Biernacka EK. Prolonged left ventricular contraction duration in apical segments as a marker of arrhythmic risk in patients with long QT syndrome. Europace 2020; 22:1279-1286. [PMID: 32529202 DOI: 10.1093/europace/euaa107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/08/2019] [Accepted: 04/10/2020] [Indexed: 12/25/2022] Open
Abstract
AIMS Long QT syndrome (LQTS) is an inherited cardiac ion channelopathy predisposing to life-threatening ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate left ventricular mechanical abnormalities in LQTS patients and establish a potential role of strain as a marker of arrhythmic risk. METHODS AND RESULTS We included 47 patients with genetically confirmed LQTS (22 LQT1, 20 LQT2, 3 LQT3, and 2 SCN3B) and 25 healthy controls. A history of cardiac events was present in 30 LQTS subjects. Tissue Doppler and speckle tracking echocardiography were performed and contraction duration was measured by radial and longitudinal strain. The radial strain characteristic was subdivided into two planes - the basal and the apical. Left ventricular ejection fraction and global longitudinal strain were normal in LQTS patients. Mean contraction duration was longer in LQTS patients compared with controls in regard to basal radial strain (491 ± 57 vs. 437 ± 55 ms, P < 0.001), apical radial strain (450 ± 53 vs. 407 ± 53 ms, P = 0.002), and longitudinal strain (445 ± 34 vs. 423 ± 43 ms, P = 0.02). Moreover, contraction duration obtained from apical radial strain analysis was longer in symptomatic compared with asymptomatic LQTS mutation carriers (462 ± 49 vs. 429 ± 55 ms, P = 0.024), as well as in subject with mutations other than LQT1 considered to be at higher risk (468 ± 50 vs. 429 ± 49 ms, P = 0.01). CONCLUSION Myocardial contraction duration is prolonged for both radial and longitudinal directions in LQTS patients. Regional left ventricular function analysis may contribute to risk stratification. Apical radial deformation seems to select subjects at higher risk of arrhythmic events.
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Affiliation(s)
- Karolina Borowiec
- Department of Congenital Heart Diseases, Institute of Cardiology, Alpejska 42, 04-628 Warsaw, Poland
| | - Mirosław Kowalski
- Department of Congenital Heart Diseases, Institute of Cardiology, Alpejska 42, 04-628 Warsaw, Poland
| | - Magdalena Kumor
- Department of Congenital Heart Diseases, Institute of Cardiology, Alpejska 42, 04-628 Warsaw, Poland
| | - Joanna Duliban
- Department of Congenital Heart Diseases, Institute of Cardiology, Alpejska 42, 04-628 Warsaw, Poland
| | - Witold Śmigielski
- Department of Demography and Social Gerontology, University of Lodz, Rewolucji 1905 r. 41, 90-214 Lodz, Poland
| | - Piotr Hoffman
- Department of Congenital Heart Diseases, Institute of Cardiology, Alpejska 42, 04-628 Warsaw, Poland
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8
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Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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9
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Lebert J, Christoph J. Synchronization-based reconstruction of electromechanical wave dynamics in elastic excitable media. CHAOS (WOODBURY, N.Y.) 2019; 29:093117. [PMID: 31575136 DOI: 10.1063/1.5101041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 08/19/2019] [Indexed: 06/10/2023]
Abstract
The heart is an elastic excitable medium, in which mechanical contraction is triggered by nonlinear waves of electrical excitation, which diffuse rapidly through the heart tissue and subsequently activate the cardiac muscle cells to contract. These highly dynamic excitation wave phenomena have yet to be fully observed within the depths of the heart muscle, as imaging technology is unable to penetrate the tissue and provide panoramic, three-dimensional visualizations necessary for adequate study. As a result, the electrophysiological mechanisms that are associated with the onset and progression of severe heart rhythm disorders such as atrial or ventricular fibrillation remain insufficiently understood. Here, we present a novel synchronization-based data assimilation approach with which it is possible to reconstruct excitation wave dynamics within the volume of elastic excitable media by observing spatiotemporal deformation patterns, which occur in response to excitation. The mechanical data are assimilated in a numerical replication of the measured elastic excitable system, and within this replication, the data drive the intrinsic excitable dynamics, which then coevolve and correspond to a reconstruction of the original dynamics. We provide a numerical proof-of-principle and demonstrate the performance of the approach by recovering even complicated three-dimensional scroll wave patterns, including vortex filaments of electrical excitation from within a deformable bulk tissue with fiber anisotropy. In the future, the reconstruction approach could be combined with high-speed imaging of the heart's mechanical contractions to estimate its electrophysiological activity for diagnostic purposes.
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Affiliation(s)
- Jan Lebert
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 42a-Heart Research Building, 37075 Göttingen, Germany
| | - Jan Christoph
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 42a-Heart Research Building, 37075 Göttingen, Germany
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10
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Sampedro-Puente DA, Fernandez-Bes J, Porter B, van Duijvenboden S, Taggart P, Pueyo E. Mechanisms Underlying Interactions Between Low-Frequency Oscillations and Beat-to-Beat Variability of Celullar Ventricular Repolarization in Response to Sympathetic Stimulation: Implications for Arrhythmogenesis. Front Physiol 2019; 10:916. [PMID: 31427979 PMCID: PMC6687852 DOI: 10.3389/fphys.2019.00916] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 07/04/2019] [Indexed: 12/12/2022] Open
Abstract
Background and Objectives: Enhanced beat-to-beat variability of ventricular repolarization (BVR) has been linked to arrhythmias and sudden cardiac death. Recent experimental studies on human left ventricular epicardial electrograms have shown that BVR closely interacts with low-frequency (LF) oscillations of activation recovery interval during sympathetic provocation. In this work human ventricular computational cell models are developed to reproduce the experimentally observed interactions between BVR and its LF oscillations, to assess underlying mechanisms and to establish a relationship with arrhythmic risk. Materials and Methods: A set of human ventricular action potential (AP) models covering a range of experimental electrophysiological characteristics was constructed. These models incorporated stochasticity in major ionic currents as well as descriptions of β-adrenergic stimulation and mechanical effects to investigate the AP response to enhanced sympathetic activity. Statistical methods based on Automatic Relevance Determination and Canonical Correlation Analysis were developed to unravel individual and common factors contributing to BVR and LF patterning of APD in response to sympathetic provocation. Results: Simulated results reproduced experimental evidences on the interactions between BVR and LF oscillations of AP duration (APD), with replication of the high inter-individual variability observed in both phenomena. ICaL, IKr and IK1 currents were identified as common ionic modulators of the inter-individual differences in BVR and LF oscillatory behavior and were shown to be crucial in determining susceptibility to arrhythmogenic events. Conclusions: The calibrated family of human ventricular cell models proposed in this study allows reproducing experimentally reported interactions between BVR and LF oscillations of APD. Ionic factors involving ICaL, IKr and IK1 currents are found to underlie correlated increments in both phenomena in response to sympathetic provocation. A link to arrhythmogenesis is established for concomitantly elevated levels of BVR and its LF oscillations.
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Affiliation(s)
| | | | - Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | | | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Esther Pueyo
- BSICOS Group, I3A, IIS Aragón, University of Zaragoza, Zaragoza, Spain.,CIBER-BBN, Madrid, Spain
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11
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Ziupa D, Menza M, Koppermann S, Moss R, Beck J, Franke G, Perez Feliz S, Brunner M, Mayer S, Bugger H, Koren G, Zehender M, Jung BA, Seemann G, Foell D, Bode C, Odening KE. Electro-mechanical (dys-)function in long QT syndrome type 1. Int J Cardiol 2019; 274:144-151. [DOI: 10.1016/j.ijcard.2018.07.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/18/2018] [Accepted: 07/06/2018] [Indexed: 01/28/2023]
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12
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Thomas D, Christ T, Fabritz L, Goette A, Hammwöhner M, Heijman J, Kockskämper J, Linz D, Odening KE, Schweizer PA, Wakili R, Voigt N. German Cardiac Society Working Group on Cellular Electrophysiology state-of-the-art paper: impact of molecular mechanisms on clinical arrhythmia management. Clin Res Cardiol 2018; 108:577-599. [PMID: 30306295 DOI: 10.1007/s00392-018-1377-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/24/2018] [Indexed: 12/19/2022]
Abstract
Cardiac arrhythmias remain a common challenge and are associated with significant morbidity and mortality. Effective and safe rhythm control strategies are a primary, yet unmet need in everyday clinical practice. Despite significant pharmacological and technological advances, including catheter ablation and device-based therapies, the development of more effective alternatives is of significant interest to increase quality of life and to reduce symptom burden, hospitalizations and mortality. The mechanistic understanding of pathophysiological pathways underlying cardiac arrhythmias has advanced profoundly, opening up novel avenues for mechanism-based therapeutic approaches. Current management of arrhythmias, however, is primarily guided by clinical and demographic characteristics of patient groups as opposed to individual, patient-specific mechanisms and pheno-/genotyping. With this state-of-the-art paper, the Working Group on Cellular Electrophysiology of the German Cardiac Society aims to close the gap between advanced molecular understanding and clinical decision-making in cardiac electrophysiology. The significance of cellular electrophysiological findings for clinical arrhythmia management constitutes the main focus of this document. Clinically relevant knowledge of pathophysiological pathways of arrhythmias and cellular mechanisms of antiarrhythmic interventions are summarized. Furthermore, the specific molecular background for the initiation and perpetuation of atrial and ventricular arrhythmias and mechanism-based strategies for therapeutic interventions are highlighted. Current "hot topics" in atrial fibrillation are critically appraised. Finally, the establishment and support of cellular and translational electrophysiology programs in clinical rhythmology departments is called for to improve basic-science-guided patient management.
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Affiliation(s)
- Dierk Thomas
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany. .,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiovascular Medicine, Division of Rhythmology, University Hospital Münster, Münster, Germany
| | - Andreas Goette
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Matthias Hammwöhner
- St. Vincenz-Hospital, Paderborn, Germany.,Working Group: Molecular Electrophysiology, University Hospital Magdeburg, Magdeburg, Germany
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.,Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jens Kockskämper
- Biochemical and Pharmacological Center (BPC) Marburg, Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Dominik Linz
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, SA, Australia.,Experimental Electrophysiology, University Hospital of Saarland, Homburg, Saar, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute for Experimental Cardiovascular Medicine, Heart Center University of Freiburg, Freiburg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.,HCR (Heidelberg Center for Heart Rhythm Disorders), Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany.,Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany
| | - Reza Wakili
- Department of Cardiology and Vascular Medicine, Medical Faculty, West German Heart Center, University Hospital Essen, Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University Göttingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. .,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Göttingen, Germany.
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13
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Charisopoulou D, Koulaouzidis G, Rydberg A, Henein MY. Abnormal ventricular repolarization in long QT syndrome carriers is related to short left ventricular filling time and attenuated stroke volume response during exercise. Echocardiography 2018; 35:1116-1123. [PMID: 29648704 DOI: 10.1111/echo.13891] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Long QT syndrome (LQTS) carriers are characterized by abnormal ventricular repolarization, prolonged systole, and mechanical dispersion. Prolonged left ventricular (LV) systole has been shown to result in disproportionate shortening of LV filling in other conditions. The aim of this study was to assess LV filling, diastolic function, and stroke volume (SV) response to dynamic exercise, in a group of LQTS carriers. METHODS Forty-seven LQTS carriers (45 ± 15 years, 20 symptomatic) and 35 healthy individuals underwent bicycle stress echocardiogram. Electrocardiographic and echocardiographic measurements were obtained at rest, peak exercise, and 4 minutes into recovery. RESULTS Long QT syndrome carriers and controls did not differ in age, gender, heart rate, QRS duration, or LV ejection fraction. At rest, LQTS carriers had longer QTc and shorter filling time (FT). At peak exercise, QTc increased and remained longer than controls at recovery. A negative correlation was found between QTc and FT (r = -.398, P = .001) with greater fall in FT in LQTS carriers than in controls at peak exercise (-23% ± 10 vs +2% ± 3, P < .0001). FT correlated with SV (r = +.27, P = .001), which increased more in controls than in LQTS carriers (+32% ± 4 vs +2% ± 1, P < .05). These differences were more pronounced in symptomatic LQTS carriers who had shorter FT and smaller SV at peak exercise and during recovery compared to asymptomatics (P < .05). CONCLUSIONS Long QT syndrome carriers have longer QTc, but also shorter FT. These disturbances worsen at peak exercise (particularly in symptomatics) compromising LV filling and SV, hence a potential pathomechanism for adverse events.
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Affiliation(s)
- Dafni Charisopoulou
- Department of Public Health and Clinical Medicine, Umea University and Heart Centre, Umea, Sweden.,Department of Paediatric Cardiology, Evelina London Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - George Koulaouzidis
- Department of Public Health and Clinical Medicine, Umea University and Heart Centre, Umea, Sweden
| | - Annika Rydberg
- Department of Clinical Sciences, Paediatrics, Umea University, Umea, Sweden
| | - Michael Y Henein
- Department of Public Health and Clinical Medicine, Umea University and Heart Centre, Umea, Sweden.,Molecular & Clinical Sciences Research Institute, St George University, London, UK
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Dressler FF, Brado J, Odening KE. Electromechanical heterogeneity in the heart : A key to long QT syndrome? Herzschrittmacherther Elektrophysiol 2018; 29:43-47. [PMID: 29234865 DOI: 10.1007/s00399-017-0544-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/24/2017] [Indexed: 06/07/2023]
Abstract
In the healthy heart, physiological heterogeneities in structure and in electrical and mechanical activity are crucial for normal, efficient excitation and pumping. Alterations of heterogeneity have been linked to arrhythmogenesis in various cardiac disorders such as long QT syndrome (LQTS). This inherited arrhythmia disorder is caused by mutations in different ion channel genes and is characterized by (heterogeneously) prolonged cardiac repolarization and increased risk for ventricular tachycardia, syncope and sudden cardiac death. Cardiac electrical and mechanical function are not independent of each other but interact in a bidirectional manner by electromechanical and mechano-electrical coupling. Therefore, changes in either process will affect the other. Recent experimental and clinical evidence suggests that LQTS, which is primarily considered an "electrical" disorder, also exhibits features of disturbed mechanical function and heterogeneity, which in turn appears to correlate with the risk of arrhythmia in the individual patient. In this review, we give a short overview of the current knowledge about physiological and pathological, long QT-related electrical and mechanical heterogeneity in the heart. Also, their respective roles for future risk prediction approaches in LQTS are discussed.
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Affiliation(s)
- F F Dressler
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - J Brado
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Medizinische Klinik und Poliklinik I, Klinikum der Universität München, Munich, Germany
| | - K E Odening
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106, Freiburg, Germany.
- Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- Institute for Experimental Cardiovascular Medicine, Heart Center, University of Freiburg, Freiburg, Germany.
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15
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Velten M, Heyob KM, Wold LE, Rogers LK. Perinatal inflammation induces sex-related differences in cardiovascular morbidities in mice. Am J Physiol Heart Circ Physiol 2018; 314:H573-H579. [PMID: 29212791 PMCID: PMC5899262 DOI: 10.1152/ajpheart.00484.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/29/2017] [Accepted: 11/30/2017] [Indexed: 01/03/2023]
Abstract
Sex-related differences in cardiovascular health and disease have been identified, with males having a higher incidence of cardiovascular events but females more likely to develop arrhythmias. Adverse fetal environments are now accepted as a cause for the development of cardiovascular diseases in adulthood, but sex-related differences in response to adverse fetal environments have not been extensively explored. The combination of both in utero and postnatal exposure to inflammation is highly relevant for the infant that is born preterm or has clinical complications at birth or in early postnatal life. We have previously observed cardiac contractile deficiencies and dysregulation of Ca2+-handling proteins in our model of maternal lipopolysaccharide (LPS) and neonatal hyperoxia exposures (LPS/O2). This investigation tested the hypothesis that there are sex-related differences in the adult pathologies after exposure to perinatal inflammation. Using pressure-volume assessments, males exposed to LPS/O2 had more pronounced contractile deficiencies than similarly exposed females, but females tended to have long PR intervals. While both sexes demonstrated decreases in α-myosin heavy chain and connexin 43 after LPS/O2 exposure compared with saline/room air controls, females indicated aberrant increases in microRNA 208a, microRNA 208b, and desmin expression. Our study supports our hypothesis that early life exposure to inflammation results in sex-dependent deficits in cardiovascular function. NEW & NOTEWORTHY Sex-specific differences in cardiovascular disease are recognized, but the mechanisms and origins are not well understood. Adverse maternal environments can influence cardiac development and later cardiovascular disease. This study identifies sex-dependent differences in cardiac disease associated with perinatal inflammation.
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Affiliation(s)
- Markus Velten
- Department of Anesthesiology and Intensive Care Medicine, Rheinische Friedrich Wilhelms University, University Medical Center , Bonn , Germany
| | - Kathryn M Heyob
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, The Ohio State University , Columbus, Ohio
| | | | - Lynette K Rogers
- Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, The Ohio State University , Columbus, Ohio
- The Ohio State University , Columbus, Ohio
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Report on the Ion Channel Symposium : Organized by the German Cardiac Society Working Group on Cellular Electrophysiology (AG 18). Herzschrittmacherther Elektrophysiol 2018; 29:4-13. [PMID: 29313139 DOI: 10.1007/s00399-017-0549-4] [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: 11/03/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
To support scientific exchange and activity in the field of cardiac cellular electrophysiology, the German Cardiac Society Working Group on Cellular Electrophysiology (AG 18) established a two-day symposium to be held every 2 years. The second Ion Channel Symposium entitled "Göttingen Channels 2017-Of Benches and Beds" took place in Göttingen from September 22nd to 23rd under the auspices of the German Cardiac Society. A group of national and international experts presented scientific advances in cardiac electrophysiology and rhythmology. The symposium's primary focus was the significance of cellular electrophysiology findings for the optimization of diagnostic and therapeutic strategies against cardiac arrhythmias. To this end, speakers, chairpersons and attendees discussed the contribution of specific molecular alterations to the initiation and perpetuation of atrial and ventricular arrhythmias. Furthermore, the meeting highlighted how discoveries in electrophysiological research may lead to novel therapeutic targets. The interdisciplinary assessment of mechanisms and therapeutic strategies of cardiac arrhythmias represented a key feature of the meeting. A unique combination of topics and speakers representing both basic science and clinical electrophysiology ensured the scientific success of the "Göttingen Channels 2017" symposium. The next Ion Channel Symposium is planned to be hosted by the incoming co-chair of the German Cardiac Society Working Group on Cellular Electrophysiology in fall 2019.
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17
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Ravens U, Aalkjaer C. Cardiac heterogeneity and drug-provoked arrhythmias. Acta Physiol (Oxf) 2017; 221:157-159. [PMID: 28613434 DOI: 10.1111/apha.12907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- U. Ravens
- Institute of Experimental Cardiovascular Medicine; University Heart Center Freiburg - Bad Krozingen; University of Freiburg; Freiburg Germany
| | - C. Aalkjaer
- Department of Biomedicine; Aarhus University; Aarhus Denmark
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18
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Abstract
PURPOSE OF REVIEW In this chapter we will discuss the most recent and relevant evidences published in the field of inherited arrhythmogenic disorders, focusing on the so called 'channelopathies' that are associated with sudden cardiac death (SCD) in children: long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome (BrS), and catecholaminergic polymorphic ventricular tachycardia (CPVT). RECENT FINDINGS We will discuss the latest diagnostic criteria for channelopathies released by the European Society of Cardiology, the new data on BrS in children and the recent evidence supporting a genotype-specific therapy for LQTS type 3. Moreover, we will present further insights into the risk stratification of the children affected by LQTS, analyzing the role of imaging for the prediction of life-threatening arrhythmias. In addition, we will offer a perspective on how to deal with genetic results in families affected by SCD at very young ages. SUMMARY The selected publications will aid pediatricians in their clinical work when managing little patients with inherited arrhythmias, providing the most recent information for diagnosis, risk stratification, and management.
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19
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Brado J, Dechant MJ, Menza M, Komancsek A, Lang CN, Bugger H, Foell D, Jung BA, Stiller B, Bode C, Odening KE. Phase-contrast magnet resonance imaging reveals regional, transmural, and base-to-apex dispersion of mechanical dysfunction in patients with long QT syndrome. Heart Rhythm 2017; 14:1388-1397. [PMID: 28479515 DOI: 10.1016/j.hrthm.2017.04.045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Indexed: 01/23/2023]
Abstract
BACKGROUND Regional dispersion of prolonged repolarization is a hallmark of long QT syndrome (LQTS). We have also revealed regional heterogeneities in mechanical dysfunction in transgenic rabbit models of LQTS. OBJECTIVE In this clinical pilot study, we investigated whether patients with LQTS exhibit dispersion of mechanical/diastolic dysfunction. METHODS Nine pediatric patients with genotyped LQTS (12.2 ± 3.3 years) and 9 age- and sex-matched healthy controls (10.6 ± 1.5 years) were subjected to phase-contrast magnetic resonance imaging to analyze radial (Vr) and longitudinal (Vz) myocardial velocities during systole and diastole in the left ventricle (LV) base, mid, and apex. Twelve-lead electrocardiograms were recorded to assess the heart rate-corrected QT (QTc) interval. RESULTS The QTc interval was longer in patients with LQTS than in controls (469.1 ± 39.4 ms vs 417.8 ± 24.4 ms; P < .01). Patients with LQTS demonstrated prolonged radial and longitudinal time-to-diastolic peak velocities (TTP), a marker for prolonged contraction duration, in the LV base, mid, and apex. The longer QTc interval positively correlated with longer time-to-diastolic peak velocities (correlation coefficient 0.63; P < .01). Peak diastolic velocities were reduced in LQTS in the LV mid and apex, indicating impaired diastolic relaxation. In patients with LQTS, regional (TTPmax-min) and transmural (TTPVz-Vr) dispersion of contraction duration was increased in the LV apex (TTPVz_max-min: 38.9 ± 25.5 ms vs 20.2 ± 14.7 ms; P = .07; TTPVz-Vr: -21.7 ± 14.5 ms vs -8.7 ± 11.3 ms; P < .05). The base-to-apex longitudinal relaxation sequence was reversed in patients with LQTS compared with controls (TTPVz_base-apex: 14.4 ± 14.9 ms vs -10.1 ± 12.7 ms; P < .01). CONCLUSION Patients with LQTS exhibit diastolic dysfunction with reduced diastolic velocities and prolonged contraction duration. Mechanical dispersion is increased in LQTS with an increased regional and transmural dispersion of contraction duration and altered apicobasal longitudinal relaxation sequence. LQTS is an electromechanical disorder, and phase-contrast magnetic resonance imaging Heterogeneity in mechanical dysfunction enables a detailed assessment of mechanical consequences of LQTS.
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Affiliation(s)
- Johannes Brado
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Markus J Dechant
- Faculty of Medicine, University of Freiburg, Freiburg, Germany; Department of Pediatric Cardiology, Heart Center, University of Freiburg, Freiburg, Germany
| | - Marius Menza
- Faculty of Medicine, University of Freiburg, Freiburg, Germany; Department of Radiology and Medical Physics, Medical Center, University of Freiburg, Freiburg, Germany
| | - Adriana Komancsek
- Faculty of Medicine, University of Freiburg, Freiburg, Germany; Department of Radiology and Medical Physics, Medical Center, University of Freiburg, Freiburg, Germany
| | - Corinna N Lang
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Heiko Bugger
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Daniela Foell
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Bernd A Jung
- Department of Diagnostic and Pediatric Radiology, University Hospital of Bern, Bern, Switzerland
| | - Brigitte Stiller
- Faculty of Medicine, University of Freiburg, Freiburg, Germany; Department of Pediatric Cardiology, Heart Center, University of Freiburg, Freiburg, Germany
| | - Christoph Bode
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany; Institute for Experimental Cardiovascular Medicine, Heart Center, University of Freiburg, Freiburg, Germany.
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Lang CN, Koren G, Odening KE. Transgenic rabbit models to investigate the cardiac ion channel disease long QT syndrome. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:142-56. [PMID: 27210307 DOI: 10.1016/j.pbiomolbio.2016.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/01/2016] [Indexed: 12/13/2022]
Abstract
Long QT syndrome (LQTS) is a rare inherited channelopathy caused mainly by different mutations in genes encoding for cardiac K(+) or Na(+) channels, but can also be caused by commonly used ion-channel-blocking and QT-prolonging drugs, thus affecting a much larger population. To develop novel diagnostic and therapeutic strategies to improve the clinical management of these patients, a thorough understanding of the pathophysiological mechanisms of arrhythmogenesis and potential pharmacological targets is needed. Drug-induced and genetic animal models of various species have been generated and have been instrumental for identifying pro-arrhythmic triggers and important characteristics of the arrhythmogenic substrate in LQTS. However, due to species differences in features of cardiac electrical function, these different models do not entirely recapitulate all aspects of the human disease. In this review, we summarize advantages and shortcomings of different drug-induced and genetically mediated LQTS animal models - focusing on mouse and rabbit models since these represent the most commonly used small animal models for LQTS that can be subjected to genetic manipulation. In particular, we highlight the different aspects of arrhythmogenic mechanisms, pro-arrhythmic triggering factors, anti-arrhythmic agents, and electro-mechanical dysfunction investigated in transgenic LQTS rabbit models and their translational application for the clinical management of LQTS patients in detail. Transgenic LQTS rabbits have been instrumental to increase our understanding of the role of spatial and temporal dispersion of repolarization to provide an arrhythmogenic substrate, genotype-differences in the mechanisms for early afterdepolarization formation and arrhythmia maintenance, mechanisms of hormonal modification of arrhythmogenesis and regional heterogeneities in electro-mechanical dysfunction in LQTS.
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Affiliation(s)
- C N Lang
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Center - University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany
| | - G Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - K E Odening
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Center - University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany.
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Quinn TA, Ripplinger CM. Recent developments in biophysics & molecular biology of heart rhythm. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 120:1-2. [PMID: 26777585 DOI: 10.1016/j.pbiomolbio.2016.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Canada.
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22
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Solovyova O, Katsnelson LB, Kohl P, Panfilov AV, Tsaturyan AK, Tsyvian PB. Mechano-electric heterogeneity of the myocardium as a paradigm of its function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:249-54. [PMID: 26713555 PMCID: PMC4821177 DOI: 10.1016/j.pbiomolbio.2015.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 11/13/2015] [Accepted: 12/16/2015] [Indexed: 01/25/2023]
Abstract
Myocardial heterogeneity is well appreciated and widely documented, from sub-cellular to organ levels. This paper reviews significant achievements of the group, led by Professor Vladimir S. Markhasin, Russia, who was one of the pioneers in studying and interpreting the relevance of cardiac functional heterogeneity.
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Affiliation(s)
- Olga Solovyova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia; Ural Federal University, Ekaterinburg, Russia.
| | - Leonid B Katsnelson
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia; Ural Federal University, Ekaterinburg, Russia.
| | - Peter Kohl
- Research Centre for Cardiovascular Medicine, University of Freiburg, Germany; National Heart and Lung Institute, Imperial College of London, UK.
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23
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Holmes JW, Laksman Z, Gepstein L. Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:134-48. [PMID: 26615948 DOI: 10.1016/j.pbiomolbio.2015.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 12/31/2022]
Abstract
Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function - maintaining integrity of the heart wall against enormous mechanical forces - but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important set of tools for improving patient outcomes across a range of heart diseases, whether used in place of or as an adjunct to regenerative approaches.
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Affiliation(s)
- Jeffrey W Holmes
- Departments of Biomedical Engineering and Medicine, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.
| | - Zachary Laksman
- Cardiac Electrophysiology, University of British Columbia, Vancouver, BC, Canada
| | - Lior Gepstein
- Departments of Cardiology (Ramban Health Care Campus) and Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa, Israel
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