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Remme CA, Heijman J, Gomez AM, Zaza A, Odening KE. 25 years of basic and translational science in EP Europace: novel insights into arrhythmia mechanisms and therapeutic strategies. Europace 2023; 25:euad210. [PMID: 37622575 PMCID: PMC10450791 DOI: 10.1093/europace/euad210] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 08/26/2023] Open
Abstract
In the last 25 years, EP Europace has published more than 300 basic and translational science articles covering different arrhythmia types (ranging from atrial fibrillation to ventricular tachyarrhythmias), different diseases predisposing to arrhythmia formation (such as genetic arrhythmia disorders and heart failure), and different interventional and pharmacological anti-arrhythmic treatment strategies (ranging from pacing and defibrillation to different ablation approaches and novel drug-therapies). These studies have been conducted in cellular models, small and large animal models, and in the last couple of years increasingly in silico using computational approaches. In sum, these articles have contributed substantially to our pathophysiological understanding of arrhythmia mechanisms and treatment options; many of which have made their way into clinical applications. This review discusses a representative selection of EP Europace manuscripts covering the topics of pacing and ablation, atrial fibrillation, heart failure and pro-arrhythmic ventricular remodelling, ion channel (dys)function and pharmacology, inherited arrhythmia syndromes, and arrhythmogenic cardiomyopathies, highlighting some of the advances of the past 25 years. Given the increasingly recognized complexity and multidisciplinary nature of arrhythmogenesis and continued technological developments, basic and translational electrophysiological research is key advancing the field. EP Europace aims to further increase its contribution to the discovery of arrhythmia mechanisms and the implementation of mechanism-based precision therapy approaches in arrhythmia management.
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Affiliation(s)
- Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC location University of Amsterdam, Heart Centre, Academic Medical Center, Room K2-104.2, Meibergdreef 11, 1105 AZ Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam, The Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine and Life Sciences, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Ana M Gomez
- Signaling and Cardiovascular Pathophysiology, UMR-S 1180, Inserm, Université Paris-Saclay, 91400 Orsay, France
| | - Antonio Zaza
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Katja E Odening
- Translational Cardiology, Department of Cardiology and Department of Physiology, Inselspital University Hospital Bern, University of Bern, 3012 Bern, Switzerland
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2
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Reiffel JA. Antiarrhythmic Drugs for Atrial Fibrillation: Selected Features of Ventricular Repolarization That Facilitate Proarrhythmic Torsades de Pointes and Favor Inpatient Initiation. J Innov Card Rhythm Manag 2021; 12:4600-4605. [PMID: 34327046 PMCID: PMC8313184 DOI: 10.19102/icrm.2021.120704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 01/15/2021] [Indexed: 12/18/2022] Open
Abstract
The management approaches to patients with atrial fibrillation (AF) include rhythm-control strategies for those patients who are symptomatic despite rate control and for selected others in whom sinus rhythm is necessary for reasons beyond current symptoms (including commercial pilots, those who are felt likely to develop symptoms as comorbidities progress, and more). First-line therapies among the rhythm-control options are antiarrhythmic drugs (AADs). For many AADs, their initiation in-hospital is either a requirement or strongly advised- especially when the patient is in AF. This article explores some of the rationale behind this requirement to give clinicians a better understanding of the reasons for this undesired inconvenience.
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3
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Bers DM, Xiang YK, Zaccolo M. Whole-Cell cAMP and PKA Activity are Epiphenomena, Nanodomain Signaling Matters. Physiology (Bethesda) 2020; 34:240-249. [PMID: 31165682 DOI: 10.1152/physiol.00002.2019] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Novel targeted fluorescent biosensors provide key insights into very local nanodomains of cAMP and PKA activity, and how they respond differently to β-adrenergic activation in cardiac myocytes. This unique spatiotemporal detail in living cells is not available with biochemical measurements of total cellular cAMP and PKA, and provides unique physiological insights.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California , Davis, California
| | - Yang K Xiang
- Department of Pharmacology, University of California , Davis, California
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford , Oxford , United Kingdom
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4
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Sampedro-Puente DA, Fernandez-Bes J, Szentandrássy N, Nánási P, Taggart P, Pueyo E. Time Course of Low-Frequency Oscillatory Behavior in Human Ventricular Repolarization Following Enhanced Sympathetic Activity and Relation to Arrhythmogenesis. Front Physiol 2020; 10:1547. [PMID: 32009971 PMCID: PMC6971219 DOI: 10.3389/fphys.2019.01547] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/09/2019] [Indexed: 11/21/2022] Open
Abstract
Background and Objectives: Recent studies in humans and dogs have shown that ventricular repolarization exhibits a low-frequency (LF) oscillatory pattern following enhanced sympathetic activity, which has been related to arrhythmic risk. The appearance of LF oscillations in ventricular repolarization is, however, not immediate, but it may take up to some minutes. This study seeks to characterize the time course of the action potential (AP) duration (APD) oscillatory behavior in response to sympathetic provocations, unveil its underlying mechanisms and establish a potential link to arrhythmogenesis under disease conditions. Materials and Methods: A representative set of human ventricular computational models coupling cellular electrophysiology, calcium dynamics, β-adrenergic signaling, and mechanics was built. Sympathetic provocation was modeled via phasic changes in β-adrenergic stimulation (β-AS) and mechanical stretch at Mayer wave frequencies within the 0.03–0.15 Hz band. Results: Our results show that there are large inter-individual differences in the time lapse for the development of LF oscillations in APD following sympathetic provocation, with some cells requiring just a few seconds and other cells needing more than 3 min. Whereas, the oscillatory response to phasic mechanical stretch is almost immediate, the response to β-AS is much more prolonged, in line with experimentally reported evidences, thus being this component the one driving the slow development of APD oscillations following enhanced sympathetic activity. If β-adrenoceptors are priorly stimulated, the time for APD oscillations to become apparent is remarkably reduced, with the oscillation time lapse being an exponential function of the pre-stimulation level. The major mechanism underlying the delay in APD oscillations appearance is related to the slow IKs phosphorylation kinetics, with its relevance being modulated by the IKs conductance of each individual cell. Cells presenting short oscillation time lapses are commonly associated with large APD oscillation magnitudes, which facilitate the occurrence of pro-arrhythmic events under disease conditions involving calcium overload and reduced repolarization reserve. Conclusions: The time course of LF oscillatory behavior of APD in response to increased sympathetic activity presents high inter-individual variability, which is associated with different expression and PKA phosphorylation kinetics of the IKs current. Short time lapses in the development of APD oscillations are associated with large oscillatory magnitudes and pro-arrhythmic risk under disease conditions.
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Affiliation(s)
| | | | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Péter Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Esther Pueyo
- BSICOS Group, I3A, IIS Aragón, University of Zaragoza, Zaragoza, Spain.,Center for Biomedical Research in the Network in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
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5
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Wang L, Morotti S, Tapa S, Francis Stuart SD, Jiang Y, Wang Z, Myles RC, Brack KE, Ng GA, Bers DM, Grandi E, Ripplinger CM. Different paths, same destination: divergent action potential responses produce conserved cardiac fight-or-flight response in mouse and rabbit hearts. J Physiol 2019; 597:3867-3883. [PMID: 31215643 DOI: 10.1113/jp278016] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/17/2019] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Cardiac electrophysiology and Ca2+ handling change rapidly during the fight-or-flight response to meet physiological demands. Despite dramatic differences in cardiac electrophysiology, the cardiac fight-or-flight response is highly conserved across species. In this study, we performed physiological sympathetic nerve stimulation (SNS) while optically mapping cardiac action potentials and intracellular Ca2+ transients in innervated mouse and rabbit hearts. Despite similar heart rate and Ca2+ handling responses between mouse and rabbit hearts, we found notable species differences in spatio-temporal repolarization dynamics during SNS. Species-specific computational models revealed that these electrophysiological differences allowed for enhanced Ca2+ handling (i.e. enhanced inotropy) in each species, suggesting that electrophysiological responses are fine-tuned across species to produce optimal cardiac fight-or-flight responses. ABSTRACT Sympathetic activation of the heart results in positive chronotropy and inotropy, which together rapidly increase cardiac output. The precise mechanisms that produce the electrophysiological and Ca2+ handling changes underlying chronotropic and inotropic responses have been studied in detail in isolated cardiac myocytes. However, few studies have examined the dynamic effects of physiological sympathetic nerve activation on cardiac action potentials (APs) and intracellular Ca2+ transients (CaTs) in the intact heart. Here, we performed bilateral sympathetic nerve stimulation (SNS) in fully innervated, Langendorff-perfused rabbit and mouse hearts. Dual optical mapping with voltage- and Ca2+ -sensitive dyes allowed for analysis of spatio-temporal AP and CaT dynamics. The rabbit heart responded to SNS with a monotonic increase in heart rate (HR), monotonic decreases in AP and CaT duration (APD, CaTD), and a monotonic increase in CaT amplitude. The mouse heart had similar HR and CaT responses; however, a pronounced biphasic APD response occurred, with initial prolongation (50.9 ± 5.1 ms at t = 0 s vs. 60.6 ± 4.1 ms at t = 15 s, P < 0.05) followed by shortening (46.5 ± 9.1 ms at t = 60 s, P = NS vs. t = 0). We determined the biphasic APD response in mouse was partly due to dynamic changes in HR during SNS and was exacerbated by β-adrenergic activation. Simulations with species-specific cardiac models revealed that transient APD prolongation in mouse allowed for greater and more rapid CaT responses, suggesting more rapid increases in contractility; conversely, the rabbit heart requires APD shortening to produce optimal inotropic responses. Thus, while the cardiac fight-or-flight response is highly conserved between species, the underlying mechanisms orchestrating these effects differ significantly.
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Affiliation(s)
- Lianguo Wang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Srinivas Tapa
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | | | - Yanyan Jiang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Zhen Wang
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Rachel C Myles
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow, UK
| | - Kieran E Brack
- Department of Cardiovascular Sciences, University of Leicester, NIHR Leicester Biomedical Research Centre, Leicester, UK
| | - G André Ng
- Department of Cardiovascular Sciences, University of Leicester, NIHR Leicester Biomedical Research Centre, Leicester, UK
| | - Donald M Bers
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, School of Medicine, University of California, Davis, USA
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6
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Grandi E, Ripplinger CM. Antiarrhythmic mechanisms of beta blocker therapy. Pharmacol Res 2019; 146:104274. [PMID: 31100336 DOI: 10.1016/j.phrs.2019.104274] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/04/2019] [Accepted: 05/13/2019] [Indexed: 02/07/2023]
Abstract
Sympathetic activity plays an important role in modulation of cardiac rhythm. Indeed, while exerting positive tropic effects in response to physiologic and pathologic stressors, β-adrenergic stimulation influences cardiac electrophysiology and can lead to disturbances of the heart rhythm and potentially lethal arrhythmias, particularly in pathological settings. For this reason, β-blockers are widely utilized clinically as antiarrhythmics. In this review, the molecular mechanisms of β-adrenergic action in the heart, the cellular and tissue level cardiac responses to β-adrenergic stimulation, and the clinical use of β-blockers as antiarrhythmic agents are reviewed. We emphasize the complex interaction between cardiomyocyte signaling, contraction, and electrophysiology occurring over multiple time- and spatial-scales during pathophysiological responses to β-adrenergic stimulation. An integrated understanding of this complex system is essential for optimizing therapies aimed at preventing arrhythmias.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, United States.
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7
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Prajapati C, Ojala M, Aalto-Setälä K. Divergent effects of adrenaline in human induced pluripotent stem cell-derived cardiomyocytes obtained from hypertrophic cardiomyopathy. Dis Model Mech 2018; 11:dmm.032896. [PMID: 29361520 PMCID: PMC5894949 DOI: 10.1242/dmm.032896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/22/2017] [Indexed: 12/26/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disease that affects the heart muscle with diverse clinical outcomes. HCM can cause sudden cardiac death (SCD) during or immediately after mild to rigorous physical activity in young patients. However, the mechanism causing SCD as a result of exercise remains unknown, but exercise-induced ventricular arrhythmias are thought to be responsible for this fatal consequence. To understand the disease mechanism behind HCM in a better way, we generated patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from HCM patients carrying either the MYBPC3-Gln1061X or TPM1-Asp175Asn mutation. We extensively investigated the effects of low to high concentrations of adrenaline on action potential characteristics, and the occurrence of arrhythmias in the presence of various concentrations of adrenaline and in wash-out condition. We classified and quantified different types of arrhythmias observed in hiPSC-CMs, and found that the occurrence of arrhythmias was dependent on concentrations of adrenaline and positions of mutations in genes causing HCM. In addition, we observed ventricular tachycardia types of arrhythmias in hiPSC-CMs carrying the TPM1-Asp175Asn mutation. We additionally examined the antiarrhythmic potency of bisoprolol in HCM-specific hiPSC-CMs. However, bisoprolol could not reduce the occurrence of arrhythmias during administration or during the wash-out condition of adrenaline in HCM-specific hiPSC-CMs. Our study demonstrates hiPSC-CMs as a promising tool for studying HCM. The experimental design used in this study could be suitable and beneficial for studying other components and drugs related to cardiac disease in general. Summary: Different concentrations of adrenaline have divergent effects during and immediately after administration in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) obtained from hypertrophic cardiomyopathy (HCM) patients. Bisoprolol could not reduce the arrhythmias in HCM-specific hiPSC-CMs.
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Affiliation(s)
| | - Marisa Ojala
- BioMediTech, University of Tampere, 33014 Tampere, Finland
| | - Katriina Aalto-Setälä
- BioMediTech, University of Tampere, 33014 Tampere, Finland .,Faculty of Medicine and Life Science, University of Tampere, 33014 Tampere, Finland.,Heart Hospital, Tampere University Hospital, 33521 Tampere, Finland
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8
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Autonomic conflict exacerbates long QT associated ventricular arrhythmias. J Mol Cell Cardiol 2018; 116:145-154. [PMID: 29408217 PMCID: PMC5855091 DOI: 10.1016/j.yjmcc.2018.02.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 01/19/2018] [Accepted: 02/01/2018] [Indexed: 11/27/2022]
Abstract
This study tested the hypothesis that concomitant sympathetic and parasympathetic stimulation (“autonomic conflict”) may act as a trigger for arrhythmias in long QT syndrome (LQTS). Studies were performed in isolated innervated rabbit hearts treated with clofilium (100 nmol/L); a potassium channel blocker. The influence of vagus nerve stimulation (VNS) on spontaneous ventricular arrhythmias was assessed in the absence/presence of sustained noradrenaline perfusion (100 nmol/L) and with sudden adrenergic stress (injections of noradrenaline into the perfusion line). Hearts were instrumented for a pseudo-electrocardiogram and monophasic action potential recordings. VNS, which slows heart rate, was associated with a stimulation frequency-dependent incidence of spontaneous early after-depolarisations (EADs) and ventricular tachycardia (VT), best predicted by the duration of the electrocardiographic T-wave and by triangulation of the ventricular action potential. In the presence of sustained (steady-state) noradrenaline perfusion, the incidence of EADs and VT with VNS was decreased from 73/55% to 45/27%, respectively. However, sudden adrenergic stress, imposed during periods of sustained VNS, was associated with a transient increase in the incidence of severity of observed arrhythmias, as indicated by an increase in the average arrhythmias score (1.6 ± 0.4 vs. 2.1 ± 0.7, p = .01). Analysis of electrophysiological parameters suggests that sudden adrenergic stress is associated with a transient prolongation, and increased triangulation, of the ventricular action potential, which may predispose to triggered activity. This study demonstrates that autonomic conflict is a pro-arrhythmic stimulus in LQTS. However, combined adrenergic and parasympathetic stimulation has a complex relationship with arrhythmogenicity, with differences in the effects of steady-state adrenergic activation vs. sudden adrenergic stress. Long QT syndrome associated arrhythmias were studied with dual autonomic stimulation. EADs and TdP were triggered by increased vagal tone. Sudden adrenergic stress increased the severity of observed arrhythmias. Arrhythmias were prevented by sustained adrenergic stimulation. The sequence of autonomic stimulation influences the severity of long QT arrhythmias.
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9
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Gemmell P, Burrage K, Rodríguez B, Quinn TA. Rabbit-specific computational modelling of ventricular cell electrophysiology: Using populations of models to explore variability in the response to ischemia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:169-84. [PMID: 27320382 PMCID: PMC5405055 DOI: 10.1016/j.pbiomolbio.2016.06.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 06/13/2016] [Indexed: 11/04/2022]
Abstract
Computational modelling, combined with experimental investigations, is a powerful method for investigating complex cardiac electrophysiological behaviour. The use of rabbit-specific models, due to the similarities of cardiac electrophysiology in this species with human, is especially prevalent. In this paper, we first briefly review rabbit-specific computational modelling of ventricular cell electrophysiology, multi-cellular simulations including cellular heterogeneity, and acute ischemia. This mini-review is followed by an original computational investigation of variability in the electrophysiological response of two experimentally-calibrated populations of rabbit-specific ventricular myocyte action potential models to acute ischemia. We performed a systematic exploration of the response of the model populations to varying degrees of ischemia and individual ischemic parameters, to investigate their individual and combined effects on action potential duration and refractoriness. This revealed complex interactions between model population variability and ischemic factors, which combined to enhance variability during ischemia. This represents an important step towards an improved understanding of the role that physiological variability may play in electrophysiological alterations during acute ischemia.
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Affiliation(s)
- Philip Gemmell
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Oxford, UK; School of Mathematical Sciences and ARC Centre of Excellence, ACEMS, Queensland University of Technology, Brisbane, Australia
| | - Blanca Rodríguez
- Department of Computer Science, University of Oxford, Oxford, UK
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, 5850 College St, Lab 3F, Halifax, NS B3H 4R2, Canada; School of Biomedical Engineering, Dalhousie University, 5850 College St, Lab 3F, Halifax, NS B3H 4R2, Canada.
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10
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Nguyen TP, Sovari AA, Pezhouman A, Iyer S, Cao H, Ko CY, Bapat A, Vahdani N, Ghanim M, Fishbein MC, Karagueuzian HS. Increased susceptibility of spontaneously hypertensive rats to ventricular tachyarrhythmias in early hypertension. J Physiol 2016; 594:1689-707. [PMID: 26775607 DOI: 10.1113/jp271318] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/07/2015] [Indexed: 01/19/2023] Open
Abstract
Hypertension is a risk factor for sudden cardiac death caused by ventricular tachycardia and fibrillation (VT/VF). We hypothesized that, in early hypertension, the susceptibility to stress-induced VT/VF increases. We compared the susceptibility of 5- to 6-month-old male spontaneously hypertensive rats (SHR) and age/sex-matched normotensive rats (NR) to VT/VF during challenge with oxidative stress (H2 O2 ; 0.15 mmol l(-1) ). We found that only SHR hearts exhibited left ventricular fibrosis and hypertrophy. H2 O2 promoted VT in all 30 SHR but none of the NR hearts. In 33% of SHR cases, focal VT degenerated to VF within 3 s. Simultaneous voltage-calcium optical mapping of Langendorff-perfused SHR hearts revealed that H2 O2 -induced VT/VF arose spontaneously from focal activations at the base and mid left ventricular epicardium. Microelectrode recording of SHR hearts showed that VT was initiated by early afterdepolarization (EAD)-mediated triggered activity. However, despite the increased susceptibility of SHR hearts to VT/VF, patch clamped isolated SHR ventricular myocytes developed EADs and triggered activity to the same extent as NR ventricular myocytes, except with larger EAD amplitude. During the early stages of hypertension, when challenged with oxidative stress, SHR hearts showed an increased ventricular arrhythmogenicity that stems primarily from tissue remodelling (hypertrophy, fibrosis) rather than cellular electrophysiological changes. Our findings highlight the need for early hypertension treatment to minimize myocardial fibrosis, ventricular hypertrophy, and arrhythmias.
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Affiliation(s)
- Thao P Nguyen
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
| | - Ali A Sovari
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine.,Present address: Department of Medicine, Cedars-Sinai Medical Centre, Los Angeles, CA, USA
| | - Arash Pezhouman
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
| | - Shankar Iyer
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
| | - Hong Cao
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine.,Present address: Department of Physiology, Wuhan University, Wuhan, China
| | - Christopher Y Ko
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
| | - Aneesh Bapat
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine.,Present address: Department of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Nooshin Vahdani
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine.,Present address: School of Pharmacy, West Coast University, Los Angeles, CA, USA
| | - Mostafa Ghanim
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
| | - Michael C Fishbein
- Department of Pathology, UCLA David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Hrayr S Karagueuzian
- UCLA Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine
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11
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Winter J, Shattock MJ. Geometrical considerations in cardiac electrophysiology and arrhythmogenesis. Europace 2015; 18:320-31. [PMID: 26585597 DOI: 10.1093/europace/euv307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/14/2015] [Indexed: 11/14/2022] Open
Abstract
The rate of repolarization (RRepol) and so the duration of the cardiac action potential are determined by the balance of inward and outward currents across the cardiac membrane (net ionic current). Plotting action potential duration (APD) as a function of the RRepol reveals an inverse non-linear relationship, arising from the geometric association between these two factors. From the RRepol-APD relationship, it can be observed that a longer action potential will exhibit a greater propensity to shorten, or prolong, for a given change in the RRepol (i.e. net ionic current), when compared with one that is initially shorter. This observation has recently been used to explain why so many interventions that prolong the action potential exert a greater effect at slow rates (reverse rate-dependence). In this article, we will discuss the broader implications of this simple principle and examine how common experimental observations on the electrical behaviour of the myocardium may be explained in terms of the RRepol-APD relationship. An argument is made, with supporting published evidence, that the non-linear relationship between the RRepol and APD is a fundamental, and largely overlooked, property of the myocardium. The RRepol-APD relationship appears to explain why interventions and disease with seemingly disparate mechanisms of action have similar electrophysiological consequences. Furthermore, the RRepol-APD relationship predicts that prolongation of the action potential, by slowing repolarization, will promote conditions of dynamic electrical instability, exacerbating several electrophysiological phenomena associated with arrhythmogenesis, namely, the rate dependence of dispersion of repolarization, APD restitution, and electrical alternans.
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Affiliation(s)
- James Winter
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
| | - Michael J Shattock
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
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12
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Gomez JF, Cardona K, Trenor B. Lessons learned from multi-scale modeling of the failing heart. J Mol Cell Cardiol 2015; 89:146-59. [PMID: 26476237 DOI: 10.1016/j.yjmcc.2015.10.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/07/2015] [Accepted: 10/14/2015] [Indexed: 12/26/2022]
Abstract
Heart failure constitutes a major public health problem worldwide. Affected patients experience a number of changes in the electrical function of the heart that predispose to potentially lethal cardiac arrhythmias. Due to the multitude of electrophysiological changes that may occur during heart failure, the scientific literature is complex and sometimes ambiguous, perhaps because these findings are highly dependent on the etiology, the stage of heart failure, and the experimental model used to study these changes. Nevertheless, a number of common features of failing hearts have been documented. Prolongation of the action potential (AP) involving ion channel remodeling and alterations in calcium handling have been established as the hallmark characteristics of myocytes isolated from failing hearts. Intercellular uncoupling and fibrosis are identified as major arrhythmogenic factors. Multi-scale computational simulations are a powerful tool that complements experimental and clinical research. The development of biophysically detailed computer models of single myocytes and cardiac tissues has contributed greatly to our understanding of processes underlying excitation and repolarization in the heart. The electrical, structural, and metabolic remodeling that arises in cardiac tissues during heart failure has been addressed from different computational perspectives to further understand the arrhythmogenic substrate. This review summarizes the contributions from computational modeling and simulation to predict the underlying mechanisms of heart failure phenotypes and their implications for arrhythmogenesis, ranging from the cellular level to whole-heart simulations. The main aspects of heart failure are presented in several related sections. An overview of the main electrophysiological and structural changes that have been observed experimentally in failing hearts is followed by the description and discussion of the simulation work in this field at the cellular level, and then in 2D and 3D cardiac structures. The implications for arrhythmogenesis in heart failure are also discussed including therapeutic measures, such as drug effects and cardiac resynchronization therapy. Finally, the future challenges in heart failure modeling and simulation will be discussed.
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Affiliation(s)
- Juan F Gomez
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Karen Cardona
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Beatriz Trenor
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
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Negroni JA, Morotti S, Lascano EC, Gomes AV, Grandi E, Puglisi JL, Bers DM. β-adrenergic effects on cardiac myofilaments and contraction in an integrated rabbit ventricular myocyte model. J Mol Cell Cardiol 2015; 81:162-75. [PMID: 25724724 DOI: 10.1016/j.yjmcc.2015.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/10/2015] [Accepted: 02/17/2015] [Indexed: 12/21/2022]
Abstract
A five-state model of myofilament contraction was integrated into a well-established rabbit ventricular myocyte model of ion channels, Ca(2+) transporters and kinase signaling to analyze the relative contribution of different phosphorylation targets to the overall mechanical response driven by β-adrenergic stimulation (β-AS). β-AS effect on sarcoplasmic reticulum Ca(2+) handling, Ca(2+), K(+) and Cl(-) currents, and Na(+)/K(+)-ATPase properties was included based on experimental data. The inotropic effect on the myofilaments was represented as reduced myofilament Ca(2+) sensitivity (XBCa) and titin stiffness, and increased cross-bridge (XB) cycling rate (XBcy). Assuming independent roles of XBCa and XBcy, the model reproduced experimental β-AS responses on action potentials and Ca(2+) transient amplitude and kinetics. It also replicated the behavior of force-Ca(2+), release-restretch, length-step, stiffness-frequency and force-velocity relationships, and increased force and shortening in isometric and isotonic twitch contractions. The β-AS effect was then switched off from individual targets to analyze their relative impact on contractility. Preventing β-AS effects on L-type Ca(2+) channels or phospholamban limited Ca(2+) transients and contractile responses in parallel, while blocking phospholemman and K(+) channel (IKs) effects enhanced Ca(2+) and inotropy. Removal of β-AS effects from XBCa enhanced contractile force while decreasing peak Ca(2+) (due to greater Ca(2+) buffering), but had less effect on shortening. Conversely, preventing β-AS effects on XBcy preserved Ca(2+) transient effects, but blunted inotropy (both isometric force and especially shortening). Removal of titin effects had little impact on contraction. Finally, exclusion of β-AS from XBCa and XBcy while preserving effects on other targets resulted in preserved peak isometric force response (with slower kinetics) but nearly abolished enhanced shortening. β-AS effects on XBCa and XBcy have greater impact on isometric and isotonic contraction, respectively.
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Affiliation(s)
- Jorge A Negroni
- Department of Comparative, Cellular and Molecular Biology, Universidad Favaloro, Buenos Aires, Argentina.
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, CA, USA
| | - Elena C Lascano
- Department of Comparative, Cellular and Molecular Biology, Universidad Favaloro, Buenos Aires, Argentina
| | - Aldrin V Gomes
- Department of Neurobiology, Physiology and Behavior, University of California Davis, CA, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, CA, USA
| | - José L Puglisi
- Department of Pharmacology, University of California Davis, CA, USA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, CA, USA.
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Severi S, Rodriguez B, Zaza A. Computational cardiac electrophysiology is ready for prime time. Europace 2014; 16:382-3. [DOI: 10.1093/europace/euu044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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