1
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Ghosh A, Raja DCC, Badhwar N, Sriram CS, Pandurangi UM. Clinical/electrophysiologic characteristics of infranodal Wenckebach in patients with indication for permanent ventricular pacing: A prospective study. Heart Rhythm 2024:S1547-5271(24)02559-1. [PMID: 38750913 DOI: 10.1016/j.hrthm.2024.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 06/16/2024]
Abstract
BACKGROUND Infranodal Wenckebach is rare and not well characterized. OBJECTIVE We prospectively studied clinical and electrophysiologic characteristics of patients with atrioventricular (AV) Wenckebach with an indication for permanent ventricular pacing. METHODS During a 2-year period, all patients with an indication for permanent ventricular pacing underwent targeted preimplantation electrophysiologic study. Clinical and electrophysiologic characteristics at presentation and ventricular pacing percentage at 6-month follow-up were evaluated. RESULTS A total of 163 patients (median age, 68 [interquartile range, 60-74] years; male, 59%; median QRS duration, 110 [90-130] ms; complete AV block in 123 [75.5%]) were included. AV Wenckebach was noted in 22 (13.4%) patients (median age, 70 [63-76.5] years; male, 54%; median QRS duration, 120 [110-140] ms) and classified as infranodal (12/163 [7.3%]) vs AV nodal (10/163 [6.1%]). Patients with infranodal Wenckebach (infrahisian in all), compared with AV nodal Wenckebach, demonstrated higher frequency with left ventricular ejection fraction ≤40% (41.7% vs 0%; P = .04), longer median HV interval (90 vs 49 ms; P = .005), lower frequency of isolated first-degree AV block (8.3% vs 60%; P = .02), higher frequency of right bundle branch block with left anterior fascicular block (75% vs 10%; P = .003), lesser PR increment at onset of AV Wenckebach (20.5 vs 80 ms; P = .002), and onset of 2:1 AV block at longer cycle lengths (91.7% vs 20%; P = .002). CONCLUSION Of patients referred for pacemaker implantation, infranodal Wenckebach was present in 27.5% (11/40) without complete AV block. It was as frequent as AV nodal Wenckebach and associated with characteristic electrophysiologic findings.
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Affiliation(s)
- Anindya Ghosh
- Department of Cardiac Electrophysiology and Pacing, Arrhythmia Heart Failure Academy, The Madras Medical Mission, Chennai, Tamil Nadu, India
| | - Deep Chandh C Raja
- Department of Cardiac Electrophysiology and Pacing, Kauvery Hospital, Chennai, Tamil Nadu, India
| | - Nitish Badhwar
- Stanford University School of Medicine, Stanford, California
| | - Chenni S Sriram
- Division of Cardiology, Sub-section of Electrophysiology, Children's Hospital of Michigan and Detroit Medical Center, Detroit, Michigan
| | - Ulhas M Pandurangi
- Department of Cardiac Electrophysiology and Pacing, Arrhythmia Heart Failure Academy, The Madras Medical Mission, Chennai, Tamil Nadu, India.
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2
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Ramlugun GS, Kulkarni K, Pallares-Lupon N, Boukens BJ, Efimov IR, Vigmond EJ, Bernus O, Walton RD. A comprehensive framework for evaluation of high pacing frequency and arrhythmic optical mapping signals. Front Physiol 2023; 14:734356. [PMID: 36755791 PMCID: PMC9901579 DOI: 10.3389/fphys.2023.734356] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 01/09/2023] [Indexed: 01/24/2023] Open
Abstract
Introduction: High pacing frequency or irregular activity due to arrhythmia produces complex optical mapping signals and challenges for processing. The objective is to establish an automated activation time-based analytical framework applicable to optical mapping images of complex electrical behavior. Methods: Optical mapping signals with varying complexity from sheep (N = 7) ventricular preparations were examined. Windows of activation centered on each action potential upstroke were derived using Hilbert transform phase. Upstroke morphology was evaluated for potential multiple activation components and peaks of upstroke signal derivatives defined activation time. Spatially and temporally clustered activation time points were grouped in to wave fronts for individual processing. Each activation time point was evaluated for corresponding repolarization times. Each wave front was subsequently classified based on repetitive or non-repetitive events. Wave fronts were evaluated for activation time minima defining sites of wave front origin. A visualization tool was further developed to probe dynamically the ensemble activation sequence. Results: Our framework facilitated activation time mapping during complex dynamic events including transitions to rotor-like reentry and ventricular fibrillation. We showed that using fixed AT windows to extract AT maps can impair interpretation of the activation sequence. However, the phase windowing of action potential upstrokes enabled accurate recapitulation of repetitive behavior, providing spatially coherent activation patterns. We further demonstrate that grouping the spatio-temporal distribution of AT points in to coherent wave fronts, facilitated interpretation of isolated conduction events, such as conduction slowing, and to derive dynamic changes in repolarization properties. Focal origins precisely detected sites of stimulation origin and breakthrough for individual wave fronts. Furthermore, a visualization tool to dynamically probe activation time windows during reentry revealed a critical single static line of conduction slowing associated with the rotation core. Conclusion: This comprehensive analytical framework enables detailed quantitative assessment and visualization of complex electrical behavior.
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Affiliation(s)
- Girish S. Ramlugun
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Inserm, Centre de Recherche Cardio-Thoracique, Bordeaux, France
| | - Kanchan Kulkarni
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Inserm, Centre de Recherche Cardio-Thoracique, Bordeaux, France
| | - Nestor Pallares-Lupon
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Inserm, Centre de Recherche Cardio-Thoracique, Bordeaux, France
| | - Bastiaan J. Boukens
- Department of Physiology, Cardiovascular Research Institute Maastricht, University Maastricht, Maastricht, Netherlands,Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Igor R. Efimov
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States,Department of Biomedical Engineering, Northwestern University, Chicago, IL, United States,Department of Medicine, Northwestern University, Chicago, IL, United States
| | - Edward J. Vigmond
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Centre National de la Recherche Scientifique (CNRS), Institut de Mathématiques de Bordeaux, UMR5251, Bordeaux, France
| | - Olivier Bernus
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Inserm, Centre de Recherche Cardio-Thoracique, Bordeaux, France
| | - Richard D. Walton
- IHU-Liryc, Fondation Bordeaux Université, Pessac-Bordeaux, France,Univ. Bordeaux, Inserm, Centre de Recherche Cardio-Thoracique, Bordeaux, France,*Correspondence: Richard D. Walton,
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3
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Krijger Juárez C, Amin AS, Offerhaus JA, Bezzina CR, Boukens BJ. Cardiac Repolarization in Health and Disease. JACC Clin Electrophysiol 2023; 9:124-138. [PMID: 36697193 DOI: 10.1016/j.jacep.2022.09.017] [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: 05/25/2022] [Revised: 09/16/2022] [Accepted: 09/21/2022] [Indexed: 12/03/2022]
Abstract
Abnormal cardiac repolarization is at the basis of life-threatening arrhythmias in various congenital and acquired cardiac diseases. Dysfunction of ion channels involved in repolarization at the cellular level are often the underlying cause of the repolarization abnormality. The expression pattern of the gene encoding the affected ion channel dictates its impact on the shape of the T-wave and duration of the QT interval, thereby setting the stage for both the occurrence of the trigger and the substrate for maintenance of the arrhythmia. Here we discuss how research into the genetic and electrophysiological basis of repolarization has provided us with insights into cardiac repolarization in health and disease and how this in turn may provide the basis for future improved patient-specific management.
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Affiliation(s)
- Christian Krijger Juárez
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Ahmad S Amin
- Department of Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Joost A Offerhaus
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Connie R Bezzina
- Department of Experimental Cardiology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Bastiaan J Boukens
- Department of Medical Biology, Amsterdam University Medical Center, Amsterdam, the Netherlands; Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands.
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4
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Keefe JA, Moore OM, Ho KS, Wehrens XHT. Role of Ca 2+ in healthy and pathologic cardiac function: from normal excitation-contraction coupling to mutations that cause inherited arrhythmia. Arch Toxicol 2023; 97:73-92. [PMID: 36214829 PMCID: PMC10122835 DOI: 10.1007/s00204-022-03385-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/15/2022] [Indexed: 01/19/2023]
Abstract
Calcium (Ca2+) ions are a key second messenger involved in the rhythmic excitation and contraction of cardiomyocytes throughout the heart. Proper function of Ca2+-handling proteins is required for healthy cardiac function, whereas disruption in any of these can cause cardiac arrhythmias. This comprehensive review provides a broad overview of the roles of Ca2+-handling proteins and their regulators in healthy cardiac function and the mechanisms by which mutations in these proteins contribute to inherited arrhythmias. Major Ca2+ channels and Ca2+-sensitive regulatory proteins involved in cardiac excitation-contraction coupling are discussed, with special emphasis on the function of the RyR2 macromolecular complex. Inherited arrhythmia disorders including catecholaminergic polymorphic ventricular tachycardia, long QT syndrome, Brugada syndrome, short QT syndrome, and arrhythmogenic right-ventricular cardiomyopathy are discussed with particular emphasis on subtypes caused by mutations in Ca2+-handling proteins.
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Affiliation(s)
- Joshua A Keefe
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Oliver M Moore
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kevin S Ho
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA. .,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA. .,Center for Space Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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5
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Stoks J, Bear LR, Vijgen J, Dendale P, Peeters R, Volders PGA, Cluitmans MJM. Understanding repolarization in the intracardiac unipolar electrogram: A long-lasting controversy revisited. Front Physiol 2023; 14:1158003. [PMID: 37089414 PMCID: PMC10119409 DOI: 10.3389/fphys.2023.1158003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/24/2023] [Indexed: 04/25/2023] Open
Abstract
Background: The optimal way to determine repolarization time (RT) from the intracardiac unipolar electrogram (UEG) has been a topic of debate for decades. RT is typically determined by either the Wyatt method or the "alternative method," which both consider UEG T-wave slope, but differently. Objective: To determine the optimal method to measure RT on the UEG. Methods: Seven pig hearts surrounded by an epicardial sock with 100 electrodes were Langendorff-perfused with selective cannulation of the left anterior descending (LAD) coronary artery and submersed in a torso-shaped tank containing 256 electrodes on the torso surface. Repolarization was prolonged in the non-LAD-regions by infusing dofetilide and shortened in the LAD-region using pinacidil. RT was determined by the Wyatt (tWyatt) and alternative (tAlt) methods, in both invasive (recorded with epicardial electrodes) and in non-invasive UEGs (reconstructed with electrocardiographic imaging). tWyatt and tAlt were compared to local effective refractory period (ERP). Results: With contact mapping, mean absolute error (MAE) of tWyatt and tAlt vs. ERP were 21 ms and 71 ms, respectively. Positive T-waves typically had an earlier ERP than negative T-waves, in line with theory. tWyatt -but not tAlt-shortened by local infusion of pinacidil. Similar results were found for the non-invasive UEGs (MAE of tWyatt and tAlt vs. ERP were 30 ms and 92 ms, respectively). Conclusion: The Wyatt method is the most accurate to determine RT from (non) invasive UEGs, based on novel and historical analyses. Using it to determine RT could unify and facilitate repolarization assessment and amplify its role in cardiac electrophysiology.
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Affiliation(s)
- Job Stoks
- Department of Cardiology, CARIM, Maastricht University Medical Center+, Maastricht, Netherlands
- Department of Advanced Computing Sciences, Maastricht University, Maastricht, Netherlands
- Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Laura R. Bear
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Johan Vijgen
- Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Paul Dendale
- Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium
| | - Ralf Peeters
- Department of Advanced Computing Sciences, Maastricht University, Maastricht, Netherlands
| | - Paul G. A. Volders
- Department of Cardiology, CARIM, Maastricht University Medical Center+, Maastricht, Netherlands
| | - Matthijs J. M. Cluitmans
- Department of Cardiology, CARIM, Maastricht University Medical Center+, Maastricht, Netherlands
- *Correspondence: Matthijs J. M. Cluitmans,
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6
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Cluitmans MJM, Bayer J, Bear LR, ter Bekke RMA, Heijman J, Coronel R, Volders PGA. The circle of reentry: Characteristics of trigger-substrate interaction leading to sudden cardiac arrest. Front Cardiovasc Med 2023; 10:1121517. [PMID: 37139119 PMCID: PMC10150924 DOI: 10.3389/fcvm.2023.1121517] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 03/28/2023] [Indexed: 05/05/2023] Open
Abstract
Sudden cardiac death is often caused by ventricular arrhythmias driven by reentry. Comprehensive characterization of the potential triggers and substrate in survivors of sudden cardiac arrest has provided insights into the trigger-substrate interaction leading to reentry. Previously, a "Triangle of Arrhythmogenesis", reflecting interactions between substrate, trigger and modulating factors, has been proposed to reason about arrhythmia initiation. Here, we expand upon this concept by separating the trigger and substrate characteristics in their spatial and temporal components. This yields four key elements that are required for the initiation of reentry: local dispersion of excitability (e.g., the presence of steep repolarization time gradients), a critical relative size of the region of excitability and the region of inexcitability (e.g., a sufficiently large region with early repolarization), a trigger that originates at a time when some tissue is excitable and other tissue is inexcitable (e.g., an early premature complex), and which occurs from an excitable region (e.g., from a region with early repolarization). We discuss how these findings yield a new mechanistic framework for reasoning about reentry initiation, the "Circle of Reentry." In a patient case of unexplained ventricular fibrillation, we then illustrate how a comprehensive clinical investigation of these trigger-substrate characteristics may help to understand the associated arrhythmia mechanism. We will also discuss how this reentry initiation concept may help to identify patients at risk, and how similar reasoning may apply to other reentrant arrhythmias.
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Affiliation(s)
- Matthijs J. M. Cluitmans
- Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
- Philips Research, Eindhoven, Netherlands
- Correspondence: Matthijs J. M. Cluitmans
| | | | | | - Rachel M. A. ter Bekke
- Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Jordi Heijman
- Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Ruben Coronel
- Department of Experimental Cardiology, Amsterdam University Medical Centre, Amsterdam, Netherlands
| | - Paul G. A. Volders
- Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
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7
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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8
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Han Y, Xiong C, Zhang LZ, Wang YD, Yang G, Guo Z. Antagonism of N/OFQ attenuates externalization of β1-adrenergic receptor and ventricular arrhythmias in acute myocardial ischemia rat model. Eur J Pharmacol 2022; 929:175139. [PMID: 35809655 DOI: 10.1016/j.ejphar.2022.175139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/02/2022] [Accepted: 07/02/2022] [Indexed: 11/18/2022]
Abstract
Nociceptin/orphanin FQ (N/OFQ) and adrenergic activations play roles in promoting cardiac arrhythmia in acute myocardial ischemia but whether N/OFQ and β1-adrenergic activities interact and how they interact in the arrhythmogenesis are still unknown. We designed this study to investigate the potential interaction of N/OFQ and β1-adrenergic activities and the underlying mechanism in arrhythmogenesis in acute myocardial ischemia. Ventricular arrhythmia was evaluated in anaesthetized rats following permanent coronary artery occlusion (CAO), in presence and absence of UFP-101 (a selective antagonist of N/OFQ receptor). The changes of β1-adrenergic receptor (β1-AR) in plasma membrane of cardiomyocytes were quantitatively evaluated and the relations with the alterations of phosphorylated Raf kinase inhibitor protein (p-RKIP) and phosphorylated connexin 43 (p-Cx43) were investigated. The ventricular arrhythmia was 59% less in the animals pre-treated with UFP-101 than the placebo-treated control (difference of means = -2.41; 95% confidence interval (CI) -2.84 to -1.99; P < 0.001). Meanwhile, p-RKIP and membrane β1-AR in the myocardium were downregulated by 59% and 24%, respectively (p-RKIP: difference of means = -6.91; 95% CI -8.38 to -5.45; P < 0.001; membrane β1-AR difference of means = -27.06; 95% CI -29.89 to -24.23; P < 0.001). Artificial upregulation of RKIP by didymin significant increased β1-AR in plasma membrane of the cardiomyocytes in the animals prone to ventricular arrhythmia. The findings may suggest that activation of N/OFQ receptor in acute myocardial ischemia induces upregulation of p-RKIP, externalization of β1-adrenergic receptor and downregulation of p-Cx43 in the cardiomyocytes, which promotes ventricular arrhythmia.
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Affiliation(s)
- Yi Han
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China
| | - Chang Xiong
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Lin-Zhong Zhang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China
| | - Yi-Di Wang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Guang Yang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Zheng Guo
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China; Key Laboratory of Cellular Physiology (Shanxi Medical University), National Education Commission, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China.
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9
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Cluitmans MJM, Bear LR, Nguyên UC, van Rees B, Stoks J, Ter Bekke RMA, Mihl C, Heijman J, Lau KD, Vigmond E, Bayer J, Belterman CNW, Abell E, Labrousse L, Rogier J, Bernus O, Haïssaguerre M, Hassink RJ, Dubois R, Coronel R, Volders PGA. Noninvasive detection of spatiotemporal activation-repolarization interactions that prime idiopathic ventricular fibrillation. Sci Transl Med 2021; 13:eabi9317. [PMID: 34788076 DOI: 10.1126/scitranslmed.abi9317] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Matthijs J M Cluitmans
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands.,Philips Research, 5656 AE Eindhoven, Netherlands
| | | | - Uyên C Nguyên
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
| | - Bianca van Rees
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
| | - Job Stoks
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
| | - Rachel M A Ter Bekke
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
| | - Casper Mihl
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands.,Department of Radiology, Maastricht University Medical Centre, 6200 MD Maastricht, Netherlands
| | - Jordi Heijman
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
| | - Kevin D Lau
- Philips Research, 5656 AE Eindhoven, Netherlands
| | | | | | - Charly N W Belterman
- Department of Experimental Cardiology, Amsterdam University Medical Centre, 1105 AZ Amsterdam, Netherlands
| | | | - Louis Labrousse
- IHU LIRYC, 33600 Pessac, France.,University of Bordeaux, 33000 Bordeaux, France.,Hôpital Haut Lévêque, University Hospital of Bordeaux, 33604 Bordeaux, France
| | - Julien Rogier
- IHU LIRYC, 33600 Pessac, France.,University of Bordeaux, 33000 Bordeaux, France.,Hôpital Haut Lévêque, University Hospital of Bordeaux, 33604 Bordeaux, France
| | - Olivier Bernus
- IHU LIRYC, 33600 Pessac, France.,University of Bordeaux, 33000 Bordeaux, France
| | - Michel Haïssaguerre
- IHU LIRYC, 33600 Pessac, France.,University of Bordeaux, 33000 Bordeaux, France.,Hôpital Haut Lévêque, University Hospital of Bordeaux, 33604 Bordeaux, France
| | - Rutger J Hassink
- Department of Cardiology, University Medical Centre Utrecht, 3584 CX Utrecht, Netherlands
| | | | - Ruben Coronel
- IHU LIRYC, 33600 Pessac, France.,Department of Experimental Cardiology, Amsterdam University Medical Centre, 1105 AZ Amsterdam, Netherlands
| | - Paul G A Volders
- Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, Netherlands
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10
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Szlovák J, Tomek J, Zhou X, Tóth N, Veress R, Horváth B, Szentandrássy N, Levijoki J, Papp JG, Herring N, Varró A, Eisner DA, Rodriguez B, Nagy N. Blockade of sodium‑calcium exchanger via ORM-10962 attenuates cardiac alternans. J Mol Cell Cardiol 2021; 153:111-122. [PMID: 33383036 PMCID: PMC8035081 DOI: 10.1016/j.yjmcc.2020.12.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 12/08/2020] [Accepted: 12/21/2020] [Indexed: 12/27/2022]
Abstract
Repolarization alternans, a periodic oscillation of long-short action potential duration, is an important source of arrhythmogenic substrate, although the mechanisms driving it are insufficiently understood. Despite its relevance as an arrhythmia precursor, there are no successful therapies able to target it specifically. We hypothesized that blockade of the sodium‑calcium exchanger (NCX) could inhibit alternans. The effects of the selective NCX blocker ORM-10962 were evaluated on action potentials measured with microelectrodes from canine papillary muscle preparations, and calcium transients measured using Fluo4-AM from isolated ventricular myocytes paced to evoke alternans. Computer simulations were used to obtain insight into the drug's mechanisms of action. ORM-10962 attenuated cardiac alternans, both in action potential duration and calcium transient amplitude. Three morphological types of alternans were observed, with differential response to ORM-10962 with regards to APD alternans attenuation. Analysis of APD restitution indicates that calcium oscillations underlie alternans formation. Furthermore, ORM-10962 did not markedly alter APD restitution, but increased post-repolarization refractoriness, which may be mediated by indirectly reduced L-type calcium current. Computer simulations reproduced alternans attenuation via ORM-10962, suggesting that it is acts by reducing sarcoplasmic reticulum release refractoriness. This results from the ORM-10962-induced sodium‑calcium exchanger block accompanied by an indirect reduction in L-type calcium current. Using a computer model of a heart failure cell, we furthermore demonstrate that the anti-alternans effect holds also for this disease, in which the risk of alternans is elevated. Targeting NCX may therefore be a useful anti-arrhythmic strategy to specifically prevent calcium driven alternans.
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Affiliation(s)
- Jozefina Szlovák
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Hungary
| | - Jakub Tomek
- Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom; Department of Computer Science, University of Oxford, United Kingdom.
| | - Xin Zhou
- Department of Computer Science, University of Oxford, United Kingdom
| | - Noémi Tóth
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Hungary
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Hungary; Faculty of Pharmacy, University of Debrecen, Hungary
| | | | | | - Julius Gy Papp
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Neil Herring
- Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - David A Eisner
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, University of Manchester, Core Technology Facility, Manchester, UK
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
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11
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Reilly M, Bruno CD, Prudencio TM, Ciccarelli N, Guerrelli D, Nair R, Ramadan M, Luban NLC, Posnack NG. Potential Consequences of the Red Blood Cell Storage Lesion on Cardiac Electrophysiology. J Am Heart Assoc 2020; 9:e017748. [PMID: 33086931 PMCID: PMC7763412 DOI: 10.1161/jaha.120.017748] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/04/2020] [Indexed: 12/17/2022]
Abstract
Background The red blood cell (RBC) storage lesion is a series of morphological, functional, and metabolic changes that RBCs undergo following collection, processing, and refrigerated storage for clinical use. Since the biochemical attributes of the RBC unit shifts with time, transfusion of older blood products may contribute to cardiac complications, including hyperkalemia and cardiac arrest. We measured the direct effect of storage age on cardiac electrophysiology and compared it with hyperkalemia, a prominent biomarker of storage lesion severity. Methods and Results Donor RBCs were processed using standard blood-banking techniques. The supernatant was collected from RBC units, 7 to 50 days after donor collection, for evaluation using Langendorff-heart preparations (rat) or human induced pluripotent stem cell-derived cardiomyocytes. Cardiac parameters remained stable following exposure to "fresh" supernatant from red blood cell units (day 7: 5.8±0.2 mM K+), but older blood products (day 40: 9.3±0.3 mM K+) caused bradycardia (baseline: 279±5 versus day 40: 216±18 beats per minute), delayed sinus node recovery (baseline: 243±8 versus day 40: 354±23 ms), and increased the effective refractory period of the atrioventricular node (baseline: 77±2 versus day 40: 93±7 ms) and ventricle (baseline: 50±3 versus day 40: 98±10 ms) in perfused hearts. Beating rate was also slowed in human induced pluripotent stem cell-derived cardiomyocytes after exposure to older supernatant from red blood cell units (-75±9%, day 40 versus control). Similar effects on automaticity and electrical conduction were observed with hyperkalemia (10-12 mM K+). Conclusions This is the first study to demonstrate that "older" blood products directly impact cardiac electrophysiology, using experimental models. These effects are likely caused by biochemical alterations in the supernatant from red blood cell units that occur over time, including, but not limited to hyperkalemia. Patients receiving large volume and/or rapid transfusions may be sensitive to these effects.
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Affiliation(s)
- Marissa Reilly
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
| | - Chantal D. Bruno
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Division of Critical Care MedicineChildren’s National HospitalWashingtonDC
| | - Tomas M. Prudencio
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
| | - Nina Ciccarelli
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
| | - Devon Guerrelli
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
| | - Raj Nair
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
| | - Manelle Ramadan
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
| | - Naomi L. C. Luban
- Division of Hematology and Laboratory MedicineChildren’s National HospitalWashingtonDC
- Department of PediatricsGeorge Washington UniversitySchool of MedicineWashingtonDC
- Department of PathologyGeorge Washington UniversitySchool of MedicineWashingtonDC
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical InnovationChildren’s National HospitalWashingtonDC
- Children’s National Heart InstituteChildren’s National HospitalWashingtonDC
- Department of PediatricsGeorge Washington UniversitySchool of MedicineWashingtonDC
- Department of Pharmacology & PhysiologyGeorge Washington UniversitySchool of MedicineWashingtonDC
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12
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13
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Tomek J, Bueno-Orovio A, Passini E, Zhou X, Minchole A, Britton O, Bartolucci C, Severi S, Shrier A, Virag L, Varro A, Rodriguez B. Development, calibration, and validation of a novel human ventricular myocyte model in health, disease, and drug block. eLife 2019; 8:48890. [PMID: 31868580 PMCID: PMC6970534 DOI: 10.7554/elife.48890] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022] Open
Abstract
Human-based modelling and simulations are becoming ubiquitous in biomedical science due to their ability to augment experimental and clinical investigations. Cardiac electrophysiology is one of the most advanced areas, with cardiac modelling and simulation being considered for virtual testing of pharmacological therapies and medical devices. Current models present inconsistencies with experimental data, which limit further progress. In this study, we present the design, development, calibration and independent validation of a human-based ventricular model (ToR-ORd) for simulations of electrophysiology and excitation-contraction coupling, from ionic to whole-organ dynamics, including the electrocardiogram. Validation based on substantial multiscale simulations supports the credibility of the ToR-ORd model under healthy and key disease conditions, as well as drug blockade. In addition, the process uncovers new theoretical insights into the biophysical properties of the L-type calcium current, which are critical for sodium and calcium dynamics. These insights enable the reformulation of L-type calcium current, as well as replacement of the hERG current model.
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Affiliation(s)
- Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Alfonso Bueno-Orovio
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Xin Zhou
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Ana Minchole
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Oliver Britton
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Chiara Bartolucci
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Bologna, Italy
| | - Stefano Severi
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Bologna, Italy
| | - Alvin Shrier
- Department of Physiology, McGill University, Montreal, Canada
| | - Laszlo Virag
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Andras Varro
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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Ledezma CA, Zhou X, Rodríguez B, Tan PJ, Díaz-Zuccarini V. A modeling and machine learning approach to ECG feature engineering for the detection of ischemia using pseudo-ECG. PLoS One 2019; 14:e0220294. [PMID: 31404081 PMCID: PMC6690680 DOI: 10.1371/journal.pone.0220294] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 07/12/2019] [Indexed: 11/19/2022] Open
Abstract
Early detection of coronary heart disease (CHD) has the potential to prevent the millions of deaths that this disease causes worldwide every year. However, there exist few automatic methods to detect CHD at an early stage. A challenge in the development of these methods is the absence of relevant datasets for their training and validation. Here, the ten Tusscher-Panfilov 2006 model and the O’Hara-Rudy model for human myocytes were used to create two populations of models that were in concordance with data obtained from healthy individuals (control populations) and included inter-subject variability. The effects of ischemia were subsequently included in the control populations to simulate the effects of mild and severe ischemic events on single cells, full ischemic cables of cells and cables of cells with various sizes of ischemic regions. Action potential and pseudo-ECG biomarkers were measured to assess how the evolution of ischemia could be quantified. Finally, two neural network classifiers were trained to identify the different degrees of ischemia using the pseudo-ECG biomarkers. The control populations showed action potential and pseudo-ECG biomarkers within the physiological ranges and the trends in the biomarkers commonly identified in ischemic patients were observed in the ischemic populations. On the one hand, inter-subject variability in the ischemic pseudo-ECGs precluded the detection and classification of early ischemic events using any single biomarker. On the other hand, the neural networks showed sensitivity and positive predictive value above 95%. Additionally, the neural networks revealed that the biomarkers that were relevant for the detection of ischemia were different from those relevant for its classification. This work showed that a computational approach could be used, when data is scarce, to validate proof-of-concept machine learning methods to detect ischemic events.
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Affiliation(s)
- Carlos A. Ledezma
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Xin Zhou
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodríguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - P. J. Tan
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Vanessa Díaz-Zuccarini
- Department of Mechanical Engineering, University College London, London, United Kingdom
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, W1W 7TS, UK
- * E-mail:
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15
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Kuzmin VS, Abramov AA, Egorov YV, Rosenshtraukh LV. Hypothermia-Induced Postrepolarization Refractoriness Is the Reason of the Atrial Myocardium Tolerance to the Bioelectrical Activity Disorders in the Hibernating and Active Ground Squirrel Citellus undulatus. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2019; 486:63-68. [PMID: 31317446 DOI: 10.1134/s0012496619030050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 11/23/2022]
Abstract
The electrophysiological mechanism of the atrial myocardium resistance to the cold-induced arrhythmias was studied in the hibernating ground squirrel Citellus undulatus. The atrial action potentials (APs) and refractoriness were recorded with microelectrodes in isolated multicellular preparations of the atrial myocardium taken from the hibernating and summer active ground squirrels (HS and SAS, respectively) at 37, 27, and 17°С to estimate the AP and refractoriness durations. In both HS and SAS, hypothermia increased the duration of the AP and refractoriness period (APD and RD, respectively), and in both animal groups RD was longer than APD under hypothermia but not at 37°С. This last observation can be a result of the postrepolarization refractoriness (PRR), which seems to contribute substantially to the atrial myocardium tolerance of the hibernating animals to the hypothermia-induced arrhythmias because it prevents afterdepolarizations.
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Affiliation(s)
- V S Kuzmin
- Institute of Experimental Cardiology, Russian Research and Production Cardiological Complex, Ministry of Health, 121552, Moscow, Russia.
| | - A A Abramov
- Institute of Experimental Cardiology, Russian Research and Production Cardiological Complex, Ministry of Health, 121552, Moscow, Russia
| | - Yu V Egorov
- Institute of Experimental Cardiology, Russian Research and Production Cardiological Complex, Ministry of Health, 121552, Moscow, Russia
| | - L V Rosenshtraukh
- Institute of Experimental Cardiology, Russian Research and Production Cardiological Complex, Ministry of Health, 121552, Moscow, Russia
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16
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Lawson BA, Burrage K, Burrage P, Drovandi CC, Bueno-Orovio A. Slow Recovery of Excitability Increases Ventricular Fibrillation Risk as Identified by Emulation. Front Physiol 2018; 9:1114. [PMID: 30210355 PMCID: PMC6121112 DOI: 10.3389/fphys.2018.01114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 07/25/2018] [Indexed: 12/28/2022] Open
Abstract
Purpose: Rotor stability and meandering are key mechanisms determining and sustaining cardiac fibrillation, with important implications for anti-arrhythmic drug development. However, little is yet known on how rotor dynamics are modulated by variability in cellular electrophysiology, particularly on kinetic properties of ion channel recovery. Methods: We propose a novel emulation approach, based on Gaussian process regression augmented with machine learning, for data enrichment, automatic detection, classification, and analysis of re-entrant biomarkers in cardiac tissue. More than 5,000 monodomain simulations of long-lasting arrhythmic episodes with Fenton-Karma ionic dynamics, further enriched by emulation to 80 million electrophysiological scenarios, were conducted to investigate the role of variability in ion channel densities and kinetics in modulating rotor-driven arrhythmic behavior. Results: Our methods predicted the class of excitation behavior with classification accuracy up to 96%, and emulation effectively predicted frequency, stability, and spatial biomarkers of functional re-entry. We demonstrate that the excitation wavelength interpretation of re-entrant behavior hides critical information about rotor persistence and devolution into fibrillation. In particular, whereas action potential duration directly modulates rotor frequency and meandering, critical windows of excitability are identified as the main determinants of breakup. Further novel electrophysiological insights of particular relevance for ventricular arrhythmias arise from our multivariate analysis, including the role of incomplete activation of slow inward currents in mediating tissue rate-dependence and dispersion of repolarization, and the emergence of slow recovery of excitability as a significant promoter of this mechanism of dispersion and increased arrhythmic risk. Conclusions: Our results mechanistically explain pro-arrhythmic effects of class Ic anti-arrhythmics in the ventricles despite their established role in the pharmacological management of atrial fibrillation. This is mediated by their slow recovery of excitability mode of action, promoting incomplete activation of slow inward currents and therefore increased dispersion of repolarization, given the larger influence of these currents in modulating the action potential in the ventricles compared to the atria. These results exemplify the potential of emulation techniques in elucidating novel mechanisms of arrhythmia and further application to cardiac electrophysiology.
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Affiliation(s)
- Brodie A Lawson
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kevin Burrage
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia.,Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Pamela Burrage
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Christopher C Drovandi
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
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17
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Skibsbye L, Bengaard AK, Uldum-Nielsen AM, Boddum K, Christ T, Jespersen T. Inhibition of Small Conductance Calcium-Activated Potassium (SK) Channels Prevents Arrhythmias in Rat Atria During β-Adrenergic and Muscarinic Receptor Activation. Front Physiol 2018; 9:510. [PMID: 29922167 PMCID: PMC5996028 DOI: 10.3389/fphys.2018.00510] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/20/2018] [Indexed: 01/18/2023] Open
Abstract
Sympathetic and vagal activation is linked to atrial arrhythmogenesis. Here we investigated the small conductance Ca2+-activated K+ (SK)-channel pore-blocker N-(pyridin-2-yl)-4-(pyridine-2-yl)thiazol-2-amine (ICA) on action potential (AP) and atrial fibrillation (AF) parameters in isolated rat atria during β-adrenergic [isoprenaline (ISO)] and muscarinic M2 [carbachol (CCh)] activation. Furthermore, antiarrhythmic efficacy of ICA was benchmarked toward the class-IC antiarrhythmic drug flecainide (Fleca). ISO increased the spontaneous beating frequency but did not affect other AP parameters. As expected, CCh hyperpolarized resting membrane potential (-6.2 ± 0.9 mV), shortened APD90 (24.2 ± 1.6 vs. 17.7 ± 1.1 ms), and effective refractory period (ERP; 20.0 ± 1.3 vs. 15.8 ± 1.3 ms). The duration of burst pacing triggered AF was unchanged in the presence of CCh compared to control atria (12.8 ± 5.3 vs. 11.2 ± 3.6 s), while β-adrenergic activation resulted in shorter AF durations (3.3 ± 1.7 s) and lower AF-frequency compared to CCh. Treatment with ICA (10 μM) in ISO -stimulated atria prolonged APD90 and ERP, while the AF burden was reduced (7.1 ± 5.5 vs. 0.1 ± 0.1 s). In CCh-stimulated atria, ICA treatment also resulted in APD90 and ERP prolongation and shorter AF durations. Fleca treatment in CCh-stimulated atria prolonged APD90 and ERP and abbreviated the AF duration to a similar extent as with ICA. Muscarinic activated atria constitutes a more arrhythmogenic substrate than β-adrenoceptor activated atria. Pharmacological inhibition of SK channels by ICA is effective under both conditions and equally efficacious to Fleca.
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Affiliation(s)
- Lasse Skibsbye
- Cardiac Physiology Laboratory, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne K Bengaard
- Cardiac Physiology Laboratory, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - A M Uldum-Nielsen
- Cardiac Physiology Laboratory, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kim Boddum
- Cardiac Physiology Laboratory, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, DZHK: German Centre for Cardiovascular Research, Hamburg, Germany
| | - Thomas Jespersen
- Cardiac Physiology Laboratory, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Pott A, Bock S, Berger IM, Frese K, Dahme T, Keßler M, Rinné S, Decher N, Just S, Rottbauer W. Mutation of the Na +/K +-ATPase Atp1a1a.1 causes QT interval prolongation and bradycardia in zebrafish. J Mol Cell Cardiol 2018; 120:42-52. [PMID: 29750993 DOI: 10.1016/j.yjmcc.2018.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/24/2018] [Accepted: 05/07/2018] [Indexed: 02/01/2023]
Abstract
The genetic underpinnings that orchestrate the vertebrate heart rate are not fully understood yet, but of high clinical importance, since diseases of cardiac impulse formation and propagation are common and severe human arrhythmias. To identify novel regulators of the vertebrate heart rate, we deciphered the pathogenesis of the bradycardia in the homozygous zebrafish mutant hiphop (hip) and identified a missense-mutation (N851K) in Na+/K+-ATPase α1-subunit (atp1a1a.1). N851K affects zebrafish Na+/K+-ATPase ion transport capacity, as revealed by in vitro pump current measurements. Inhibition of the Na+/K+-ATPase in vivo indicates that hip rather acts as a hypomorph than being a null allele. Consequently, reduced Na+/K+-ATPase function leads to prolonged QT interval and refractoriness in the hip mutant heart, as shown by electrocardiogram and in vivo electrical stimulation experiments. We here demonstrate for the first time that Na+/K+-ATPase plays an essential role in heart rate regulation by prolonging myocardial repolarization.
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Affiliation(s)
- Alexander Pott
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Sarah Bock
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Ina M Berger
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Karen Frese
- Department of Internal Medicine III, Heidelberg University Medical Center, Heidelberg, Germany
| | - Tillman Dahme
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Mirjam Keßler
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Niels Decher
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Steffen Just
- Molecular Cardiology, Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany.
| | - Wolfgang Rottbauer
- Department of Internal Medicine II, Ulm University Medical Center, Ulm, Germany.
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Mechano-electrical feedback in the clinical setting: Current perspectives. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:365-375. [DOI: 10.1016/j.pbiomolbio.2017.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 12/13/2022]
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20
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Murphy SR, Wang L, Wang Z, Domondon P, Lang D, Habecker BA, Myles RC, Ripplinger CM. β-Adrenergic Inhibition Prevents Action Potential and Calcium Handling Changes during Regional Myocardial Ischemia. Front Physiol 2017; 8:630. [PMID: 28894423 PMCID: PMC5581400 DOI: 10.3389/fphys.2017.00630] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022] Open
Abstract
β-adrenergic receptor (β-AR) blockers may be administered during acute myocardial infarction (MI), as they reduce energy demand through negative chronotropic and inotropic effects and prevent ischemia-induced arrhythmogenesis. However, the direct effects of β-AR blockers on ventricular electrophysiology and intracellular Ca2+ handling during ischemia remain unknown. Using optical mapping of transmembrane potential (with RH237) and sarcoplasmic reticulum (SR) Ca2+ (with the low-affinity indicator Fluo-5N AM), the effects of 15 min of regional ischemia were assessed in isolated rabbit hearts (n = 19). The impact of β-AR inhibition on isolated hearts was assessed by pre-treatment with 100 nM propranolol (Prop) prior to ischemia (n = 7). To control for chronotropy and inotropy, hearts were continuously paced at 3.3 Hz and contraction was inhibited with 20 μM blebbistatin. Untreated ischemic hearts displayed prototypical shortening of action potential duration (APD80) in the ischemic zone (IZ) compared to the non-ischemic zone (NI) at 10 and 15 min ischemia, whereas APD shortening was prevented with Prop. Untreated ischemic hearts also displayed significant changes in SR Ca2+ handling in the IZ, including prolongation of SR Ca2+ reuptake and SR Ca2+ alternans, which were prevented with Prop pre-treatment. At 5 min ischemia, Prop pre-treated hearts also showed larger SR Ca2+ release amplitude in the IZ compared to untreated hearts. These results suggest that even when controlling for chronotropic and inotropic effects, β-AR inhibition has a favorable effect during acute regional ischemia via direct effects on APD and Ca2+ handling.
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Affiliation(s)
- Shannon R Murphy
- Department of Pharmacology, University of California, DavisDavis, CA, United States
| | - Lianguo Wang
- Department of Pharmacology, University of California, DavisDavis, CA, United States
| | - Zhen Wang
- Department of Pharmacology, University of California, DavisDavis, CA, United States
| | - Philip Domondon
- Department of Biomedical Engineering, University of California, DavisDavis, CA, United States
| | - Di Lang
- Department of Pharmacology, University of California, DavisDavis, CA, United States
| | - Beth A Habecker
- Department of Physiology and Pharmacology, Oregon Health & Science UniversityPortland, OR, United States
| | - Rachel C Myles
- Institute of Cardiovascular and Medical Sciences, University of GlasgowGlasgow, United Kingdom
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, DavisDavis, CA, United States
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Spatiotemporal characterization of the transition from sinus rhythm to ventricular fibrillation during an acute ischemic event in the intact human heart by whole-heart sock-mapping. HeartRhythm Case Rep 2017; 3:259-263. [PMID: 28736709 PMCID: PMC5509912 DOI: 10.1016/j.hrcr.2017.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Coronel R. Restitution slope is determined by the steady state action potential duration: law and disorder. Cardiovasc Res 2017; 113:705-707. [PMID: 28444140 DOI: 10.1093/cvr/cvx080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ruben Coronel
- Department of Experimental Cardiology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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Dutta S, Mincholé A, Quinn TA, Rodriguez B. Electrophysiological properties of computational human ventricular cell action potential models under acute ischemic conditions. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 129:40-52. [PMID: 28223156 DOI: 10.1016/j.pbiomolbio.2017.02.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/30/2016] [Accepted: 02/15/2017] [Indexed: 11/18/2022]
Abstract
Acute myocardial ischemia is one of the main causes of sudden cardiac death. The mechanisms have been investigated primarily in experimental and computational studies using different animal species, but human studies remain scarce. In this study, we assess the ability of four human ventricular action potential models (ten Tusscher and Panfilov, 2006; Grandi et al., 2010; Carro et al., 2011; O'Hara et al., 2011) to simulate key electrophysiological consequences of acute myocardial ischemia in single cell and tissue simulations. We specifically focus on evaluating the effect of extracellular potassium concentration and activation of the ATP-sensitive inward-rectifying potassium current on action potential duration, post-repolarization refractoriness, and conduction velocity, as the most critical factors in determining reentry vulnerability during ischemia. Our results show that the Grandi and O'Hara models required modifications to reproduce expected ischemic changes, specifically modifying the intracellular potassium concentration in the Grandi model and the sodium current in the O'Hara model. With these modifications, the four human ventricular cell AP models analyzed in this study reproduce the electrophysiological alterations in repolarization, refractoriness, and conduction velocity caused by acute myocardial ischemia. However, quantitative differences are observed between the models and overall, the ten Tusscher and modified O'Hara models show closest agreement to experimental data.
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Affiliation(s)
- Sara Dutta
- Department of Computer Science, University of Oxford, Oxford, UK.
| | - Ana Mincholé
- Department of Computer Science, University of Oxford, Oxford, UK
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, UK
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Abstract
In this review, the pro- and anti-arrhythmic effects of a diet rich in fish oil fatty acids and of hypercholesterolemia will be discussed in relation to two major mechanisms of arrhythmogenesis (triggered activity and re-entry). Whereas a diet rich in fish oil is pro-arrhythmic in relation to re-entry based arrhythmias (as occur in acute myocardial ischemia) and anti-arrhythmic in relation to triggered activity based arrhythmias (as occur in heart failure), the reverse is true for hypercholesterolemia. Changing the lipid composition of cardiomyocytes likely has powerful pro- or anti-arrhythmic consequences, depending on the mechanism of arrhythmias, and has corresponding therapeutic potential.
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Affiliation(s)
- R Coronel
- Dept. Exp. Cardiology, Academic Medical Center, Amsterdam, The Netherlands; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac Bordeaux, France.
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25
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Rodriguez B, Carusi A, Abi-Gerges N, Ariga R, Britton O, Bub G, Bueno-Orovio A, Burton RAB, Carapella V, Cardone-Noott L, Daniels MJ, Davies MR, Dutta S, Ghetti A, Grau V, Harmer S, Kopljar I, Lambiase P, Lu HR, Lyon A, Minchole A, Muszkiewicz A, Oster J, Paci M, Passini E, Severi S, Taggart P, Tinker A, Valentin JP, Varro A, Wallman M, Zhou X. Human-based approaches to pharmacology and cardiology: an interdisciplinary and intersectorial workshop. Europace 2016; 18:1287-98. [PMID: 26622055 PMCID: PMC5006958 DOI: 10.1093/europace/euv320] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/20/2015] [Indexed: 12/12/2022] Open
Abstract
Both biomedical research and clinical practice rely on complex datasets for the physiological and genetic characterization of human hearts in health and disease. Given the complexity and variety of approaches and recordings, there is now growing recognition of the need to embed computational methods in cardiovascular medicine and science for analysis, integration and prediction. This paper describes a Workshop on Computational Cardiovascular Science that created an international, interdisciplinary and inter-sectorial forum to define the next steps for a human-based approach to disease supported by computational methodologies. The main ideas highlighted were (i) a shift towards human-based methodologies, spurred by advances in new in silico, in vivo, in vitro, and ex vivo techniques and the increasing acknowledgement of the limitations of animal models. (ii) Computational approaches complement, expand, bridge, and integrate in vitro, in vivo, and ex vivo experimental and clinical data and methods, and as such they are an integral part of human-based methodologies in pharmacology and medicine. (iii) The effective implementation of multi- and interdisciplinary approaches, teams, and training combining and integrating computational methods with experimental and clinical approaches across academia, industry, and healthcare settings is a priority. (iv) The human-based cross-disciplinary approach requires experts in specific methodologies and domains, who also have the capacity to communicate and collaborate across disciplines and cross-sector environments. (v) This new translational domain for human-based cardiology and pharmacology requires new partnerships supported financially and institutionally across sectors. Institutional, organizational, and social barriers must be identified, understood and overcome in each specific setting.
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Affiliation(s)
- Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, UK
| | | | - Najah Abi-Gerges
- AnaBios Corporation, San Diego Science Center, San Diego, CA 92109, USA
| | - Rina Ariga
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Oliver Britton
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Gil Bub
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | - Rebecca A B Burton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | | | - Matthew J Daniels
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | | | - Sara Dutta
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Andre Ghetti
- AnaBios Corporation, San Diego Science Center, San Diego, CA 92109, USA
| | - Vicente Grau
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Stephen Harmer
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
| | - Ivan Kopljar
- Discovery Sciences, Dis&Dev Research, Janssen Pharmaceutical NV, Beerse, Belgium
| | - Pier Lambiase
- Institute of Cardiovascular Science, University College London, Bars Heart Centre, London, UK
| | - Hua Rong Lu
- Discovery Sciences, Dis&Dev Research, Janssen Pharmaceutical NV, Beerse, Belgium
| | - Aurore Lyon
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Ana Minchole
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Anna Muszkiewicz
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Julien Oster
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Michelangelo Paci
- Department of Electronics and Communications Engineering, Tampere University of Technology, BioMediTech, Tampere, Finland
| | - Elisa Passini
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Stefano Severi
- Department of Electrical, Electronic and Information Engineering, University of Bologna, Cesena 47521, Italy
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, Bars Heart Centre, London, UK
| | - Andy Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, UK
| | | | | | | | - Xin Zhou
- Department of Computer Science, University of Oxford, Oxford, UK
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26
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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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Effects of central sympathetic activation on repolarization-dispersion during short-term myocardial ischemia in anesthetized rats. Life Sci 2015; 144:170-7. [PMID: 26679103 DOI: 10.1016/j.lfs.2015.12.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Revised: 11/08/2015] [Accepted: 12/07/2015] [Indexed: 12/28/2022]
Abstract
AIMS Sympathetic activation during myocardial ischemia enhances arrhythmogenesis, but the underlying pathophysiologic mechanisms remain unclear. We investigated the central sympathetic effects on ventricular repolarization during the early-period post-coronary artery occlusion. MAIN METHODS We studied 12 Wistar rats (254±2 g) for 30 min following left coronary artery ligation, with (n=6) or without (n=6) pretreatment with the central sympatholytic agent clonidine. Mapping of left and right ventricular epicardial electrograms was performed with a 32-electrode array. As an index of sympathetic activation, heart rate variability in the frequency domain was calculated. Heart rate and repolarization duration were measured with a custom-made recording and analysis software, followed by calculation of intra- and inter-ventricular dispersion of repolarization. KEY FINDINGS Heart rate and heart rate variability indicated lower sympathetic activation in clonidine-treated rats during ischemia. Repolarization duration in the left ventricle prolonged after clonidine at baseline, independently of heart rate, but no differences were present 30 min post-ligation. Dispersion of repolarization in the right ventricle remained stable during ischemia, whereas it increased in the left ventricle, equally in both groups. A similar trend was observed for inter-ventricular dispersion, without differences between groups. SIGNIFICANCE In addition to intra-ventricular repolarization-dispersion, anterior-wall myocardial ischemia may also increase inter-ventricular repolarization-dispersion. Progressive central sympathetic activation occurs during myocardial ischemia, but it does not affect intra- or inter-ventricular dispersion of ventricular repolarization during the early phase. Further research is warranted on the potential effects during subsequent time-periods.
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Machhada A, Ang R, Ackland GL, Ninkina N, Buchman VL, Lythgoe MF, Trapp S, Tinker A, Marina N, Gourine AV. Control of ventricular excitability by neurons of the dorsal motor nucleus of the vagus nerve. Heart Rhythm 2015; 12:2285-93. [PMID: 26051529 PMCID: PMC4631809 DOI: 10.1016/j.hrthm.2015.06.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND The central nervous origins of functional parasympathetic innervation of cardiac ventricles remain controversial. OBJECTIVE This study aimed to identify a population of vagal preganglionic neurons that contribute to the control of ventricular excitability. An animal model of synuclein pathology relevant to Parkinson's disease was used to determine whether age-related loss of the activity of the identified group of neurons is associated with changes in ventricular electrophysiology. METHODS In vivo cardiac electrophysiology was performed in anesthetized rats in conditions of selective inhibition of the dorsal vagal motor nucleus (DVMN) neurons by pharmacogenetic approach and in mice with global genetic deletion of all family members of the synuclein protein. RESULTS In rats anesthetized with urethane (in conditions of systemic beta-adrenoceptor blockade), muscarinic and neuronal nitric oxide synthase blockade confirmed the existence of a tonic parasympathetic control of cardiac excitability mediated by the actions of acetylcholine and nitric oxide. Acute DVMN silencing led to shortening of the ventricular effective refractory period (vERP), a lowering of the threshold for triggered ventricular tachycardia, and prolongation of the corrected QT (QTc) interval. Lower resting activity of the DVMN neurons in aging synuclein-deficient mice was found to be associated with vERP shortening and QTc interval prolongation. CONCLUSION Activity of the DVMN vagal preganglionic neurons is responsible for tonic parasympathetic control of ventricular excitability, likely to be mediated by nitric oxide. These findings provide the first insight into the central nervous substrate that underlies functional parasympathetic innervation of the ventricles and highlight its vulnerability in neurodegenerative diseases.
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Affiliation(s)
- Asif Machhada
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom; Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom
| | - Richard Ang
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom; William Harvey Heart Centre, Barts & The London School of Medicine and Dentistry, London, United Kingdom
| | - Gareth L Ackland
- Department of Medicine, University College London, London, United Kingdom
| | - Natalia Ninkina
- School of Biosciences, University of Cardiff, Cardiff, United Kingdom
| | | | - Mark F Lythgoe
- Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Andrew Tinker
- William Harvey Heart Centre, Barts & The London School of Medicine and Dentistry, London, United Kingdom
| | - Nephtali Marina
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.
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Abstract
Although cardiac sodium channel blocking drugs can exert antiarrhythmic actions, they can also provoke life-threatening arrhythmias through a variety of mechanisms. This review addresses the way in which drugs interact with the channel, and how these effects translate to clinical beneficial or detrimental effects. A further understanding of the details of channel function and of drug-channel interactions may lead to the development of safer and more effective antiarrhythmic therapies.
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Affiliation(s)
- Dan M Roden
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232
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Sulkin MS, Boukens BJ, Tetlow M, Gutbrod SR, Ng FS, Efimov IR. Mitochondrial depolarization and electrophysiological changes during ischemia in the rabbit and human heart. Am J Physiol Heart Circ Physiol 2014; 307:H1178-86. [PMID: 25128175 PMCID: PMC4200335 DOI: 10.1152/ajpheart.00437.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/14/2014] [Indexed: 12/31/2022]
Abstract
Instability of the inner mitochondrial membrane potential (ΔΨm) has been implicated in electrical dysfunction, including arrhythmogenesis during ischemia-reperfusion. Monitoring ΔΨm has led to conflicting results, where depolarization has been reported as sporadic and as a propagating wave. The present study was designed to resolve the aforementioned difference and determine the unknown relationship between ΔΨm and electrophysiology. We developed a novel imaging modality for simultaneous optical mapping of ΔΨm and transmembrane potential (Vm). Optical mapping was performed using potentiometric dyes on preparations from 4 mouse hearts, 14 rabbit hearts, and 7 human hearts. Our data showed that during ischemia, ΔΨm depolarization is sporadic and changes asynchronously with electrophysiological changes. Spatially, ΔΨm depolarization was associated with action potential duration shortening but not conduction slowing. Analysis of focal activity indicated that ΔΨm is not different within the myocardium where the focus originates compared with normal ventricular tissue. Overall, our data suggest that during ischemia, mitochondria maintain their function at the expense of sarcolemmal electrophysiology, but ΔΨm depolarization does not have a direct association to ischemia-induced arrhythmias.
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Affiliation(s)
- Matthew S Sulkin
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Bas J Boukens
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Megan Tetlow
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Sarah R Gutbrod
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Fu Siong Ng
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
| | - Igor R Efimov
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri
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31
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Ng FS, Holzem KM, Koppel AC, Janks D, Gordon F, Wit AL, Peters NS, Efimov IR. Adverse remodeling of the electrophysiological response to ischemia-reperfusion in human heart failure is associated with remodeling of metabolic gene expression. Circ Arrhythm Electrophysiol 2014; 7:875-82. [PMID: 25114062 DOI: 10.1161/circep.113.001477] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Ventricular arrhythmias occur more frequently in heart failure during episodes of ischemia-reperfusion although the mechanisms underlying this in humans are unclear. We assessed, in explanted human hearts, the remodeled electrophysiological response to acute ischemia-reperfusion in heart failure and its potential causes, including the remodeling of metabolic gene expression. METHODS AND RESULTS We optically mapped coronary-perfused left ventricular wedge preparations from 6 human end-stage failing hearts (F) and 6 donor hearts rejected for transplantation (D). Preparations were subjected to 30 minutes of global ischemia, followed by 30 minutes of reperfusion. Failing hearts had exaggerated electrophysiological responses to ischemia-reperfusion, with greater action potential duration shortening (P<0.001 at 8-minute ischemia; P=0.001 at 12-minute ischemia) and greater conduction slowing during ischemia, delayed recovery of electric excitability after reperfusion (F, 4.8±1.8 versus D, 1.0±0 minutes; P<0.05), and incomplete restoration of action potential duration and conduction velocity early after reperfusion. Expression of 46 metabolic genes was probed using custom-designed TaqMan arrays, using extracted RNA from 15 failing and 9 donor hearts. Ten genes important in cardiac metabolism were downregulated in heart failure, with SLC27A4 and KCNJ11 significantly downregulated at a false discovery rate of 0%. CONCLUSIONS We demonstrate, for the first time in human hearts, that the electrophysiological response to ischemia-reperfusion in heart failure is accelerated during ischemia with slower recovery after reperfusion. This can enhance spatial conduction and repolarization gradients across the ischemic border and increase arrhythmia susceptibility. This adverse response was associated with downregulation of expression of cardiac metabolic genes.
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Affiliation(s)
- Fu Siong Ng
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Katherine M Holzem
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Aaron C Koppel
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Deborah Janks
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Fabiana Gordon
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Andrew L Wit
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Nicholas S Peters
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.)
| | - Igor R Efimov
- From the Department of Biomedical Engineering, Washington University in Saint Louis, MO (F.S.N., K.M.H., A.C.K., D.J., I.R.E.); National Heart & Lung Institute (F.S.N., N.S.P.) and Statistical Advisory Service (F.G.), Imperial College London, London, United Kingdom; and Department of Pharmacology, Columbia University, New York, NY (A.L.W.).
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Lingman M, Hartford M, Karlsson T, Herlitz J, Rubulis A, Caidahl K, Bergfeldt L. Transient repolarization alterations dominate the initial phase of an acute anterior infarction--a vectorcardiography study. J Electrocardiol 2014; 47:478-85. [PMID: 24891262 DOI: 10.1016/j.jelectrocard.2014.04.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To study effects of ischemia-reperfusion on ventricular electrophysiology in humans by three-dimensional electrocardiography. METHODS Fifty-seven patients with first-time acute anterior ST elevation myocardial infarction were monitored from admission and >24h after symptom onset with continuous vectorcardiography (VCG; modified Frank orthogonal leads). Global ventricular depolarization and repolarization (VR) measures were compared at maximum vs. minimum ST vector magnitude (STVM) (median 208; 111-303 vs. 362; 165-1359min after symptom onset). RESULTS At maximum vs. minimum STVM the Tarea (overall VR dispersion) almost tripled (118 vs. 41μVs; p<0.0001), the T-loop bulginess was 90% greater (Tavplan 0.91 vs 0.48μV; p<0.0001), and Tpeak-end/QT was 39% larger (0.32 vs 0.23; p<0.0001). QRSarea (overall dispersion of depolarization) was 12% larger at maximum STVM, while QRS duration was 10% longer at minimum STVM. CONCLUSIONS Ischemia-reperfusion was accompanied by profound and transient alterations of VR dispersion, while changes in depolarization were modest and delayed.
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Affiliation(s)
- Markus Lingman
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Medicine, Halland Hospital, Varberg, Sweden.
| | - Marianne Hartford
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Thomas Karlsson
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Johan Herlitz
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Center of Prehospital Research in Western Sweden, University of Borås, Borås, Sweden
| | - Aigars Rubulis
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Kenneth Caidahl
- Department of Clinical Physiology, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Lennart Bergfeldt
- Institute of Medicine, Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Functional roles of KATP channel subunits in metabolic inhibition. J Mol Cell Cardiol 2013; 62:90-8. [PMID: 23624089 DOI: 10.1016/j.yjmcc.2013.04.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 03/11/2013] [Accepted: 04/15/2013] [Indexed: 11/23/2022]
Abstract
ATP-sensitive potassium channel (KATP) activation can drastically shorten action potential duration (APD) in metabolically compromised myocytes. We showed previously that SUR1 with Kir6.2 forms the functional channel in mouse atria while Kir6.2 and SUR2A predominate in ventricles. SUR1 is more sensitive to metabolic stress than SUR2A, raising the possibility that KATP in atria and ventricles may respond differently to metabolic stress. Action potential duration (APD) and calcium transient duration (CaTD) were measured simultaneously in both atria and ventricles by optical mapping of the posterior surface of Langendorff-perfused hearts from C57BL wild-type (WT; n=11), Kir6.2(-/-) (n=5), and SUR1(-/-) (n=6) mice during metabolic inhibition (MI, 0mM glucose+2mM sodium cyanide). After variable delay, MI led to significant shortening of APD in WT hearts. On average, atrial APD shortened by 60.5 ± 2.7% at 13.1 ± 2.1 min (n=6, p<0.01) after onset of MI. Ventricular APD shortening (56.4 ± 10.0% shortening at 18.2 ± 1.8 min) followed atrial APD shortening. In SUR1(-/-) hearts (n=6), atrial APD shortening was abolished, but ventricular shortening (65.0 ± 15.4% at 25.33 ± 4.48 min, p<0.01) was unaffected. In Kir6.2(-/-) hearts, two disparate responses to MI were observed; 3 of 5 hearts displayed slight shortening of APD in the ventricles (24 ± 3%, p<0.05) and atria (39.0 ± 1.9%, p<0.05) but this shortening occurred later and to much less extent than in WT (p<0.05). Marked prolongation of ventricular APD was observed in the remaining hearts (327% and 489% prolongation) and was associated with occurrence of ventricular tachyarrhythmias. The results confirm that Kir6.2 contributes to APD shortening in both atria and ventricle during metabolic stress, and that SUR1 is required for atrial APD shortening while SUR2A is required for ventricular APD shortening. Importantly, the results show that the presence of SUR1-dependent KATP in the atria results in the action potential being more susceptible to metabolically driven shortening than the ventricle.
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Quinn TA, Kohl P. Combining wet and dry research: experience with model development for cardiac mechano-electric structure-function studies. Cardiovasc Res 2013; 97:601-11. [PMID: 23334215 PMCID: PMC3583260 DOI: 10.1093/cvr/cvt003] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 01/08/2013] [Accepted: 01/15/2013] [Indexed: 11/17/2022] Open
Abstract
Since the development of the first mathematical cardiac cell model 50 years ago, computational modelling has become an increasingly powerful tool for the analysis of data and for the integration of information related to complex cardiac behaviour. Current models build on decades of iteration between experiment and theory, representing a collective understanding of cardiac function. All models, whether computational, experimental, or conceptual, are simplified representations of reality and, like tools in a toolbox, suitable for specific applications. Their range of applicability can be explored (and expanded) by iterative combination of 'wet' and 'dry' investigation, where experimental or clinical data are used to first build and then validate computational models (allowing integration of previous findings, quantitative assessment of conceptual models, and projection across relevant spatial and temporal scales), while computational simulations are utilized for plausibility assessment, hypotheses-generation, and prediction (thereby defining further experimental research targets). When implemented effectively, this combined wet/dry research approach can support the development of a more complete and cohesive understanding of integrated biological function. This review illustrates the utility of such an approach, based on recent examples of multi-scale studies of cardiac structure and mechano-electric function.
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Affiliation(s)
- T Alexander Quinn
- National Heart and Lung Institute, Imperial College London, Heart Science Centre, Harefield UB9 6JH, UK.
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Coronary artery disease and ventricular tachyarrhythmia: pathophysiology and treatment. Curr Opin Pharmacol 2013; 13:210-7. [PMID: 23357129 DOI: 10.1016/j.coph.2013.01.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/04/2013] [Accepted: 01/07/2013] [Indexed: 01/01/2023]
Abstract
Ventricular tachyarrhythmias are common consequences of coronary artery disease. During the prehospital phase of acute myocardial infarction (MI), ischemia-induced electrophysiological changes and genetic factors are responsible for their occurrence, but the precise pathophysiologic mechanisms are ill-understood. Primary percutaneous coronary interventions (PCIs) have decreased the incidence of ventricular tachyarrhythmias during subsequent stages, and future treatments ameliorating reperfusion injury may provide further progress. In the chronic phase, antiarrhythmic drug therapy targeted toward arrhythmogenic substrate has relatively limited value, but alternative approaches are still uncertain. By contrast, prompt arrhythmia termination by implantable cardioverter-defibrillators (ICDs) is highly effective, although risk-stratification algorithms in candidate patients are inadequate. This review explores current views in the pathophysiology and treatment of ventricular tachyarrhythmias at different clinical stages.
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Coronel R, Janse MJ, Opthof T, Wilde AA, Taggart P. Postrepolarization Refractoriness in Acute Ischemia and After Antiarrhythmic Drug Administration. Heart Rhythm 2012. [DOI: 10.1016/j.hrthm.2012.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Pandit SV, Noujaim SF, Jalife J. Postrepolarization refractoriness in acute ischemia and after antiarrhythmic drug administration. Heart Rhythm 2012; 9:e13-4; author reply e14. [PMID: 22426151 DOI: 10.1016/j.hrthm.2012.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Indexed: 11/15/2022]
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