1
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Pullinger TK, Sobie EA. Cell-to-cell heterogeneity in ion channel conductance impacts substrate vulnerability to arrhythmia. Am J Physiol Heart Circ Physiol 2024; 327:H242-H254. [PMID: 38758124 DOI: 10.1152/ajpheart.00645.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 05/06/2024] [Accepted: 05/15/2024] [Indexed: 05/18/2024]
Abstract
Determining whether an ectopic depolarization will lead to a self-perpetuating arrhythmia is of critical importance in determining arrhythmia risk, so it is necessary to understand what factors impact substrate vulnerability. This study sought to explore the impact of cell-to-cell heterogeneity in ion channel conductance on substrate vulnerability to arrhythmia by measuring the duration of the vulnerable window in computational models of one-dimensional cables of ventricular cardiomyocytes. We began by using a population of uniform cable models to determine the mechanisms underlying the vulnerable window phenomenon. We found that in addition to the known importance of GNa, the conductances GCa,L and GKr also play a minor role in determining the vulnerable window duration. We also found that a steeper slope of the repolarizing action potential during the vulnerable window correlated with a shorter vulnerable window duration in uniform cables. We applied our understanding from these initial simulations to an investigation of the vulnerable window in heterogeneous cable models. The heterogeneous cables displayed a great deal of intra-cable variation in vulnerable window duration, highly sensitive to the cardiomyocytes in the local environment of the ectopic stimulus. Coupling strength modulated not only the magnitude of the vulnerable window duration but also the extent of intra-tissue variability in vulnerable window duration.NEW & NOTEWORTHY We investigate the impact of cell-to-cell heterogeneity in ion channel conductance on substrate vulnerability to arrhythmia by measuring the vulnerable window duration in computational cardiomyocyte cable models. We demonstrate a wide range of intra-cable variability in vulnerable window duration (VWD) and show how this is changed by ion channel block and coupling strength perturbations.
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Affiliation(s)
- Taylor K Pullinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Eric A Sobie
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States
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2
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Ran A, Hu S, Huang X, Quan L, Liu M, Liu H. Neural network aided extended Kalman filtering for inverse imaging of cardiac transmembrane potential. Phys Med Biol 2024; 69:135011. [PMID: 38843814 DOI: 10.1088/1361-6560/ad550e] [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: 01/09/2024] [Accepted: 06/06/2024] [Indexed: 06/27/2024]
Abstract
Objective.The aim of this study is to address the limitations in reconstructing the electrical activity of the heart from the body surface electrocardiogram, which is an ill-posed inverse problem. Current methods often assume values commonly used in the literature in the absence ofa prioriknowledge, leading to errors in the model. Furthermore, most methods ignore the dynamic activation process inherent in cardiomyocytes during the cardiac cycle.Approach.To overcome these limitations, we propose an extended Kalman filter (EKF)-based neural network approach to dynamically reconstruct cardiac transmembrane potential (TMP). Specifically, a recurrent neural network is used to establish the state estimation equation of the EKF, while a convolutional neural network is used as the measurement equation. The Jacobi matrix of the network undergoes a correction feedback process to obtain the Kalman gain.Main results.After repeated iterations, the final estimated state vector, i.e. the reconstructed image of the TMP, is obtained. The results from both the final simulation and real experiments demonstrate the robustness and accurate quantification of the model.Significance.This study presents a new approach to cardiac TMP reconstruction that offers higher accuracy and robustness compared to traditional methods. The use of neural networks and EKFs allows dynamic modelling that takes into account the activation processes inherent in cardiomyocytes and does not requirea prioriknowledge of inputs such as forward transition matrices.
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Affiliation(s)
- Ao Ran
- State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang University, Hangzhou, People's Republic of China
| | - Shujin Hu
- State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang University, Hangzhou, People's Republic of China
| | - Xufeng Huang
- State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang University, Hangzhou, People's Republic of China
| | - Liuliu Quan
- Department of Medical Oncology, National Cancer Center/ National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, People's Republic of China
| | - Muqing Liu
- State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang University, Hangzhou, People's Republic of China
| | - Huafeng Liu
- State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang University, Hangzhou, People's Republic of China
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3
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Zhang Y, Zhang Z, Qu Z. Curvature-mediated source and sink effects on the genesis of premature ventricular complexes in long QT syndrome. Am J Physiol Heart Circ Physiol 2024; 326:H1350-H1365. [PMID: 38551483 DOI: 10.1152/ajpheart.00004.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 03/13/2024] [Accepted: 03/25/2024] [Indexed: 05/08/2024]
Abstract
Premature ventricular complexes (PVCs) are spontaneous excitations occurring in the ventricles of the heart that are associated with ventricular arrhythmias and sudden cardiac death. Under long QT conditions, PVCs can be mediated by repolarization gradient (RG) and early afterdepolarizations (EADs), yet the effects of heterogeneities or geometry of the RG or EAD regions on PVC genesis remain incompletely understood. In this study, we use computer simulation to systematically investigate the effects of the curvature of the RG border region on PVC genesis under long QT conditions. We show that PVCs can be either promoted or suppressed by negative or positive RG border curvature depending on the source and sink conditions. When the origin of oscillation is in the source region and the source is too strong, a positive RG border curvature can promote PVCs by causing the source area to oscillate. When the origin of oscillation is in the sink region, a negative RG border curvature can promote PVCs by causing the sink area to oscillate. Furthermore, EAD-mediated PVCs are also promoted by negative border curvature. We also investigate the effects of wavefront curvature and show that PVCs are promoted by convex but suppressed by concave wavefronts; however, the effect of wavefront curvature is much smaller than that of RG border curvature. In conclusion, besides the increase of RG and occurrence of EADs caused by QT prolongation, the geometry of the RG border plays important roles in PVC genesis, which can greatly increase the risk of arrhythmias in cardiac diseases.NEW & NOTEWORTHY The effects of the curvature or geometry of the repolarization gradient region and wavefront curvature on the genesis of premature ventricular complexes are systematically investigated using computer modeling and simulation. Premature ventricular complexes can be promoted by either positive or negative curvature of the gradient region depending on the source and sink conditions. The underlying mechanisms of the curvature effects are revealed, which provides mechanistic insights into arrhythmogenesis in cardiac diseases.
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Affiliation(s)
- Yuhao Zhang
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, People's Republic of China
| | - Zhaoyang Zhang
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, People's Republic of China
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States
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4
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Roman-Campos D, Marin-Neto JA, Santos-Miranda A, Kong N, D’Avila A, Rassi A. Arrhythmogenic Manifestations of Chagas Disease: Perspectives From the Bench to Bedside. Circ Res 2024; 134:1379-1397. [PMID: 38723031 PMCID: PMC11081486 DOI: 10.1161/circresaha.124.324507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/13/2024]
Abstract
Chagas cardiomyopathy caused by infection with the intracellular parasite Trypanosoma cruzi is the most common and severe expression of human Chagas disease. Heart failure, systemic and pulmonary thromboembolism, arrhythmia, and sudden cardiac death are the principal clinical manifestations of Chagas cardiomyopathy. Ventricular arrhythmias contribute significantly to morbidity and mortality and are the major cause of sudden cardiac death. Significant gaps still exist in the understanding of the pathogenesis mechanisms underlying the arrhythmogenic manifestations of Chagas cardiomyopathy. This article will review the data from experimental studies and translate those findings to draw hypotheses about clinical observations. Human- and animal-based studies at molecular, cellular, tissue, and organ levels suggest 5 main pillars of remodeling caused by the interaction of host and parasite: immunologic, electrical, autonomic, microvascular, and contractile. Integrating these 5 remodeling processes will bring insights into the current knowledge in the field, highlighting some key features for future management of this arrhythmogenic disease.
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Affiliation(s)
- Danilo Roman-Campos
- Departamento de Biofísica, Escola Paulsita de Medicina, Laboratório de Cardiobiologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil (D.R-C)
| | - José Antonio Marin-Neto
- Unidade de Hemodinâmica e Cardiologia Intervencionista, Escola de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil (J.A.M-N.)
| | - Artur Santos-Miranda
- Departamento de Fisiologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil (A.S.-M)
| | - Nathan Kong
- Departamento de Biofísica, Escola Paulsita de Medicina, Laboratório de Cardiobiologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil (D.R-C)
- Unidade de Hemodinâmica e Cardiologia Intervencionista, Escola de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil (J.A.M-N.)
- Departamento de Fisiologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil (A.S.-M)
- Hospital do Coração Anis Rassi, Goiânia, GO, Brazil (A.R.J.)
| | - André D’Avila
- Departamento de Biofísica, Escola Paulsita de Medicina, Laboratório de Cardiobiologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil (D.R-C)
- Unidade de Hemodinâmica e Cardiologia Intervencionista, Escola de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil (J.A.M-N.)
- Departamento de Fisiologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil (A.S.-M)
- Hospital do Coração Anis Rassi, Goiânia, GO, Brazil (A.R.J.)
| | - Anis Rassi
- Hospital do Coração Anis Rassi, Goiânia, GO, Brazil (A.R.J.)
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Załęska-Kocięcka M, Wojdyńska Z, Kalisz M, Litwiniuk A, Mączewski M, Leszek P, Paterek A. Epicardial fat and ventricular arrhythmias. Heart Rhythm 2024; 21:206-212. [PMID: 37972673 DOI: 10.1016/j.hrthm.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 11/03/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
The arrhythmogenic role of epicardial adipose tissue (EAT) in atrial arrhythmias is well established, but its effect on ventricular arrhythmias has been significantly less investigated. Since ventricular arrhythmias are thought to cause 75%-80% of cases of sudden cardiac death, this is not a trivial issue. We provide an overview of clinical data as well as experimental and molecular data linking EAT to ventricular arrhythmias, attempting to dissect possible mechanisms and indicate future directions of research and possible clinical implications. However, despite a wealth of data indicating the role of epicardial and intramyocardial fat in the induction and propagation of ventricular arrhythmias, unfortunately there is currently no direct evidence that indeed EAT triggers arrhythmia or can be a target for antiarrhythmic strategies.
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Affiliation(s)
- Marta Załęska-Kocięcka
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Zuzanna Wojdyńska
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Małgorzata Kalisz
- Department of Clinical Neuroendocrinology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Anna Litwiniuk
- Department of Clinical Neuroendocrinology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Michał Mączewski
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Przemysław Leszek
- Heart Failure and Transplantology Department, Mechanical Circulatory Support and Transplant Department, National Institute of Cardiology, Warsaw, Poland
| | - Aleksandra Paterek
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland.
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6
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Wang R, Qu Z, Huang X. Dissecting the roles of calcium cycling and its coupling with voltage in the genesis of early afterdepolarizations in cardiac myocyte models. PLoS Comput Biol 2024; 20:e1011930. [PMID: 38416778 PMCID: PMC10927084 DOI: 10.1371/journal.pcbi.1011930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 03/11/2024] [Accepted: 02/19/2024] [Indexed: 03/01/2024] Open
Abstract
Early afterdepolarizations (EADs) are abnormal depolarizations during the plateau phase of the action potential, which are known to be associated with lethal arrhythmias in the heart. There are two major hypotheses for EAD genesis based on experimental observations, i.e., the voltage (Vm)-driven and intracellular calcium (Ca)-driven mechanisms. In ventricular myocytes, Ca and Vm are bidirectionally coupled, which can affect each other's dynamics and result in new dynamics, however, the roles of Ca cycling and its coupling with Vm in the genesis of EADs have not been well understood. In this study, we use an action potential model that is capable of independent Vm and Ca oscillations to investigate the roles of Vm and Ca coupling in EAD genesis. Four different mechanisms of EADs are identified, which are either driven by Vm oscillations or Ca oscillations alone, or oscillations caused by their interactions. We also use 5 other ventricular action potential models to assess these EAD mechanisms and show that EADs in these models are mainly Vm-driven. These mechanistic insights from our simulations provide a theoretical base for understanding experimentally observed EADs and EAD-related arrhythmogenesis.
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Affiliation(s)
- Rui Wang
- Department of Physics, South China University of Technology, Guangzhou, China
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Xiaodong Huang
- Department of Physics, South China University of Technology, Guangzhou, China
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7
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Wang X, Landaw J, Qu Z. Intracellular ion accumulation in the genesis of complex action potential dynamics under cardiac diseases. Phys Rev E 2024; 109:024410. [PMID: 38491656 PMCID: PMC11325458 DOI: 10.1103/physreve.109.024410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/19/2024] [Indexed: 03/18/2024]
Abstract
Intracellular ions, including sodium (Na^{+}), calcium (Ca^{2+}), and potassium (K^{+}), etc., accumulate slowly after a change of the state of the heart, such as a change of the heart rate. The goal of this study is to understand the roles of slow ion accumulation in the genesis of cardiac memory and complex action-potential duration (APD) dynamics that can lead to lethal cardiac arrhythmias. We carry out numerical simulations of a detailed action potential model of ventricular myocytes under normal and diseased conditions, which exhibit memory effects and complex APD dynamics. We develop a low-dimensional iterated map (IM) model to describe the dynamics of Na^{+}, Ca^{2+}, and APD and use it to uncover the underlying dynamical mechanisms. The development of the IM model is informed by simulation results under the normal condition. We then use the IM model to perform linear stability analyses and computer simulations to investigate the bifurcations and complex APD dynamics, which depend on the feedback loops between APD and intracellular Ca^{2+} and Na^{+} concentrations and the steepness of the APD response to the ion concentrations. When the feedback between APD and Ca^{2+} concentration is positive, a Hopf bifurcation leading to periodic oscillatory behavior occurs as the steepness of the APD response to the ion concentrations increases. The negative feedback loop between APD and Na^{+} concentration is required for the Hopf bifurcation. When the feedback between APD and Ca^{2+} concentration is negative, period-doubling bifurcations leading to high periodicity and chaos occurs. In this case, Na^{+} accumulation plays little role in the dynamics. Finally, we carry out simulations of the detailed action potential model under two diseased conditions, which exhibit steep APD responses to ion concentrations. Under both conditions, Hopf bifurcations leading to slow oscillations or period-doubling bifurcations leading to high periodicity and chaotic APD dynamics occur, depending on the strength of the ion pump-Na^{+}-Ca^{2+} exchanger. Using functions reconstructed from the simulation data, the IM model accurately captures the bifurcations and dynamics under the two diseased conditions. In conclusion, besides using computer simulations of a detailed high-dimensional action-potential model to investigate the effects of slow ion accumulation and short-term memory on bifurcations and genesis of complex APD dynamics in cardiac myocytes under diseased conditions, this study also provides a low-dimensional mathematical tool, i.e., the IM model, to allow stability analyses for uncovering the underlying mechanisms.
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Affiliation(s)
- Xinyu Wang
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Julian Landaw
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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8
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Rodriguez-Rivera GJ, Post A, John M, Buchan S, Bernard D, Razavi M, Cosgriff-Hernandez E. Injectable hydrogel electrodes as conduction highways to restore native pacing. Nat Commun 2024; 15:64. [PMID: 38167848 PMCID: PMC10762156 DOI: 10.1038/s41467-023-44419-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
There is an urgent clinical need for a treatment regimen that addresses the underlying pathophysiology of ventricular arrhythmias, the leading cause of sudden cardiac death. The current report describes the design of an injectable hydrogel electrode and successful deployment in a pig model with access far more refined than any current pacing modalities allow. In addition to successful cardiac capture and pacing, analysis of surface ECG tracings and three-dimensional electroanatomic mapping revealed a QRS morphology comparable to native sinus rhythm, strongly suggesting the hydrogel electrode captures the deep septal bundle branches and Purkinje fibers. In an ablation model, electroanatomic mapping data demonstrated that the activation wavefront from the hydrogel reaches the mid-myocardium and endocardium much earlier than current single-point pacing modalities. Such uniform activation of broad swaths of tissue enables an opportunity to minimize the delayed myocardial conduction of heterogeneous tissue that underpins re-entry. Collectively, these studies demonstrate the feasibility of a new pacing modality that most closely resembles native conduction with the potential to eliminate lethal re-entrant arrhythmias and provide painless defibrillation.
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Affiliation(s)
| | - Allison Post
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA
| | - Mathews John
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA
| | - Skylar Buchan
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA
| | - Drew Bernard
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA
| | - Mehdi Razavi
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA.
- Division of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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9
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Kolk MZH, Ruipérez-Campillo S, Alvarez-Florez L, Deb B, Bekkers EJ, Allaart CP, Van Der Lingen ALCJ, Clopton P, Išgum I, Wilde AAM, Knops RE, Narayan SM, Tjong FVY. Dynamic prediction of malignant ventricular arrhythmias using neural networks in patients with an implantable cardioverter-defibrillator. EBioMedicine 2024; 99:104937. [PMID: 38118401 PMCID: PMC10772563 DOI: 10.1016/j.ebiom.2023.104937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/20/2023] [Accepted: 12/12/2023] [Indexed: 12/22/2023] Open
Abstract
BACKGROUND Risk stratification for ventricular arrhythmias currently relies on static measurements that fail to adequately capture dynamic interactions between arrhythmic substrate and triggers over time. We trained and internally validated a dynamic machine learning (ML) model and neural network that extracted features from longitudinally collected electrocardiograms (ECG), and used these to predict the risk of malignant ventricular arrhythmias. METHODS A multicentre study in patients implanted with an implantable cardioverter-defibrillator (ICD) between 2007 and 2021 in two academic hospitals was performed. Variational autoencoders (VAEs), which combine neural networks with variational inference principles, and can learn patterns and structure in data without explicit labelling, were trained to encode the mean ECG waveforms from the limb leads into 16 variables. Supervised dynamic ML models using these latent ECG representations and clinical baseline information were trained to predict malignant ventricular arrhythmias treated by the ICD. Model performance was evaluated on a hold-out set, using time-dependent receiver operating characteristic (ROC) and calibration curves. FINDINGS 2942 patients (61.7 ± 13.9 years, 25.5% female) were included, with a total of 32,129 ECG recordings during a mean follow-up of 43.9 ± 35.9 months. The mean time-varying area under the ROC curve for the dynamic model was 0.738 ± 0.07, compared to 0.639 ± 0.03 for a static (i.e. baseline-only model). Feature analyses indicated dynamic changes in latent ECG representations, particularly those affecting the T-wave morphology, were of highest importance for model predictions. INTERPRETATION Dynamic ML models and neural networks effectively leverage routinely collected longitudinal ECG recordings for personalised and updated predictions of malignant ventricular arrhythmias, outperforming static models. FUNDING This publication is part of the project DEEP RISK ICD (with project number 452019308) of the research programme Rubicon which is (partly) financed by the Dutch Research Council (NWO). This research is partly funded by the Amsterdam Cardiovascular Sciences (personal grant F.V.Y.T).
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Affiliation(s)
- Maarten Z H Kolk
- Department of Clinical and Experimental Cardiology, Amsterdam UMC Location University of Amsterdam, Heart Center, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam, the Netherlands
| | - Samuel Ruipérez-Campillo
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA; Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology Zurich (ETHz), Gloriastrasse 35, Zurich, Switzerland; ITACA Institute, Universtitat Politècnica de València, Camino de Vera S/n, Valencia, Spain
| | - Laura Alvarez-Florez
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center Location University of Amsterdam, Meibergdreef 9, Amsterdam, the Netherlands
| | - Brototo Deb
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Erik J Bekkers
- Faculty of Science, University of Amsterdam, Science Park 904, Amsterdam, the Netherlands
| | - Cornelis P Allaart
- Department of Cardiology, Amsterdam UMC, Location VU Medical Center, De Boelelaan 1118, Amsterdam, the Netherlands
| | | | - Paul Clopton
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Ivana Išgum
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center Location University of Amsterdam, Meibergdreef 9, Amsterdam, the Netherlands; Faculty of Science, University of Amsterdam, Science Park 904, Amsterdam, the Netherlands; Department of Radiology and Nuclear Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, Amsterdam, the Netherlands
| | - Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Amsterdam UMC Location University of Amsterdam, Heart Center, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam, the Netherlands
| | - Reinoud E Knops
- Department of Clinical and Experimental Cardiology, Amsterdam UMC Location University of Amsterdam, Heart Center, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam, the Netherlands
| | - Sanjiv M Narayan
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Fleur V Y Tjong
- Department of Clinical and Experimental Cardiology, Amsterdam UMC Location University of Amsterdam, Heart Center, Meibergdreef 9, Amsterdam, the Netherlands; Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA; Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam, the Netherlands.
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10
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Liu MB, Ajijola OA. The promise of cardiac neuromodulation: can computational modelling bridge the gap? J Physiol 2023; 601:3693-3694. [PMID: 37535053 PMCID: PMC10529398 DOI: 10.1113/jp285309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/04/2023] Open
Affiliation(s)
- Michael B Liu
- Division of Cardiovascular Medicine, Stanford University, Palo Alto, CA, USA
| | - Olujimi A Ajijola
- UCLA Cardiac Arrhythmia Center, University of California, Los Angeles, CA, USA
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11
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Wang C, Hao W. Cardiac arrhythmia and immune response in COVID-19 patients. Allergol Immunopathol (Madr) 2023; 51:63-70. [PMID: 37422781 DOI: 10.15586/aei.v51i4.883] [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: 03/30/2023] [Accepted: 04/15/2023] [Indexed: 07/11/2023]
Abstract
The coronavirus disease 2019 (COVID-19) pandemic has presented substantial challenges for providing health care due to the numerous complications on the respiratory and cardiovascular systems of people. Cardiac arrhythmia is one of the cardiac complications, and it was observed in COVID-19 patients. Moreover, arrhythmia and cardiac arrest are common in COVID-19 patients in the intensive care unit. The occurrence of cardiac arrhythmia in COVID-19 patients is associated with hypoxia, cytokine storm, myocardial ischemia and inflammatory disease such as congestive heart failure. It is necessary to know the occurrence and mechanisms of tachyarrhythmia and bradyarrhythmia in patients with COVID-19 infection for their proper management. This review provides an overview of the association between COVID-19 and arrhythmias by detailing possible pathophysiological mechanisms.
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Affiliation(s)
- Chunlian Wang
- Institute for Prevention and Control of Chronic Non-communicable Diseases, Harbin Center for Disease Control and Prevention, Harbin, China
| | - Wenqiang Hao
- The Second Ward of Internal Medicine, The Second Hospital of Heilongjiang Province, Harbin, China; ;
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12
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Khederlou H, Azimi Pirsaraei SV, Rabbani E, Motedayen M. Correlations between Cardiovascular Risk Factors and Ventricular Arrhythmias Following Primary Percutaneous Coronary Intervention in Patients with ST-Elevation Myocardial Infarction. J Tehran Heart Cent 2023; 18:122-128. [PMID: 37637277 PMCID: PMC10459337 DOI: 10.18502/jthc.v18i2.13322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 03/28/2023] [Indexed: 08/29/2023] Open
Abstract
Background Ventricular arrhythmias (VAs), which result from acute myocardial infarction and revascularization, are preventable causes of sudden cardiac death. This study aimed to determine the incidence, types, and risk factors of VAs in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI). Methods This cross-sectional study was conducted at the cardiology department of a tertiary care cardiac center in Zanjan, Iran. All the patients were monitored during hospitalization, and the incidence of cardiac arrhythmias and the outcomes were recorded. Results Among 315 patients, the mean age was 62.14±10.11 years, and 76.2% were male. Male gender was significantly associated with VA occurrence (P=0.038). Among the patients, 50.5% had VAs, of which 26.4% were sustained ventricular tachycardia (sustained VT) and ventricular fibrillation (VF). Sustained VT and VF, but not total arrhythmias, were more common in anterior infarctions. Most arrhythmias occurred during the first 12 hours, and frequent premature ventricular contractions (43.3%) and idioventricular rhythm (20.1%) were the most common. A history of PCI and coronary artery bypass grafting (CABG) was associated with substantially reduced arrhythmias (P=0.017 and P=0.013, respectively). However, cardiovascular risk factors exerted no statistically significant effects on the VA type. Conclusion Approximately half of our patients experienced reperfusion-induced VAs. Overall, gender and a history of PCI and CABG were significantly associated with VA occurrence. Therefore, males and patients without a positive history of PCI and CABG should receive antiarrhythmic drugs as a precaution.
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Affiliation(s)
- Hamid Khederlou
- Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Elaheh Rabbani
- School of Public Health, Iran University of Medical Sciences, Tehran, Iran
| | - Morteza Motedayen
- Department of Cardiology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
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13
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Lin J, Qu Z, Huang X. Bifurcations to transient and oscillatory excitations in inhomogeneous excitable media: Insights into arrhythmogenesis in long QT syndrome. Phys Rev E 2023; 107:034402. [PMID: 37073009 PMCID: PMC10583175 DOI: 10.1103/physreve.107.034402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 02/21/2023] [Indexed: 04/20/2023]
Abstract
Ventricular arrhythmias are the leading cause of sudden cardiac death. Understanding the mechanisms of arrhythmia initiation is important for developing effective therapeutics for prevention. Arrhythmias can be induced via premature external stimuli or occur spontaneously via dynamical instabilities. Computer simulations have shown that a large repolarization gradient due to regional prolongation of the action potential duration can result in instabilities leading to premature excitations and arrhythmias, but the bifurcation remains to be elucidated. In this study we carry out numerical simulations and linear stability analyses using a one-dimensional heterogeneous cable consisting of the FitzHugh-Nagumo model. We show that a Hopf bifurcation leads to local oscillations, which, once their amplitudes are large enough, lead to spontaneous propagating excitations. Depending on the degree of heterogeneities, these excitations can range from one to many and to be sustained oscillations, manifesting as premature ventricular contractions (PVCs) and sustained arrhythmias. The dynamics depends on the repolarization gradient and the length of the cable. Complex dynamics is also induced by the repolarization gradient. The mechanistic insights from the simple model may help in the understanding of the genesis of PVCs and arrhythmias in long QT syndrome.
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Affiliation(s)
- Jianying Lin
- Department of physics, South China University of Technology, Guangzhou 510641, China
| | - Zhilin Qu
- Department of Medicine, University of California, Los Angeles, California 90095, USA
| | - Xiaodong Huang
- Department of physics, South China University of Technology, Guangzhou 510641, China
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14
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Kolk MZH, Deb B, Ruipérez-Campillo S, Bhatia NK, Clopton P, Wilde AAM, Narayan SM, Knops RE, Tjong FVY. Machine learning of electrophysiological signals for the prediction of ventricular arrhythmias: systematic review and examination of heterogeneity between studies. EBioMedicine 2023; 89:104462. [PMID: 36773349 PMCID: PMC9945642 DOI: 10.1016/j.ebiom.2023.104462] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/19/2023] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND Ventricular arrhythmia (VA) precipitating sudden cardiac arrest (SCD) is among the most frequent causes of death and pose a high burden on public health systems worldwide. The increasing availability of electrophysiological signals collected through conventional methods (e.g. electrocardiography (ECG)) and digital health technologies (e.g. wearable devices) in combination with novel predictive analytics using machine learning (ML) and deep learning (DL) hold potential for personalised predictions of arrhythmic events. METHODS This systematic review and exploratory meta-analysis assesses the state-of-the-art of ML/DL models of electrophysiological signals for personalised prediction of malignant VA or SCD, and studies potential causes of bias (PROSPERO, reference: CRD42021283464). Five electronic databases were searched to identify eligible studies. Pooled estimates of the diagnostic odds ratio (DOR) and summary area under the curve (AUROC) were calculated. Meta-analyses were performed separately for studies using publicly available, ad-hoc datasets, versus targeted clinical data acquisition. Studies were scored on risk of bias by the PROBAST tool. FINDINGS 2194 studies were identified of which 46 were included in the systematic review and 32 in the meta-analysis. Pooling of individual models demonstrated a summary AUROC of 0.856 (95% CI 0.755-0.909) for short-term (time-to-event up to 72 h) prediction and AUROC of 0.876 (95% CI 0.642-0.980) for long-term prediction (time-to-event up to years). While models developed on ad-hoc sets had higher pooled performance (AUROC 0.919, 95% CI 0.867-0.952), they had a high risk of bias related to the re-use and overlap of small ad-hoc datasets, choices of ML tool and a lack of external model validation. INTERPRETATION ML and DL models appear to accurately predict malignant VA and SCD. However, wide heterogeneity between studies, in part due to small ad-hoc datasets and choice of ML model, may reduce the ability to generalise and should be addressed in future studies. FUNDING This publication is part of the project DEEP RISK ICD (with project number 452019308) of the research programme Rubicon which is (partly) financed by the Dutch Research Council (NWO). This research is partly funded by the Amsterdam Cardiovascular Sciences (personal grant F.V.Y.T).
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Affiliation(s)
- Maarten Z H Kolk
- Amsterdam UMC Location University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart failure & arrhythmias, Amsterdam, The Netherlands
| | - Brototo Deb
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | | | - Neil K Bhatia
- Department of Cardiology, Emory University, Atlanta, GA, USA
| | - Paul Clopton
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Arthur A M Wilde
- Amsterdam UMC Location University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart failure & arrhythmias, Amsterdam, The Netherlands
| | - Sanjiv M Narayan
- Department of Medicine and Cardiovascular Institute, Stanford University, Stanford, CA, USA
| | - Reinoud E Knops
- Amsterdam UMC Location University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart failure & arrhythmias, Amsterdam, The Netherlands
| | - Fleur V Y Tjong
- Amsterdam UMC Location University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Meibergdreef 9, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Heart failure & arrhythmias, Amsterdam, The Netherlands.
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15
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Jiang X, Ning P, Yan F, Wang J, Cai W, Yang F. Impact of myeloid differentiation protein 1 on cardiovascular disease. Biomed Pharmacother 2023; 157:114000. [PMID: 36379121 DOI: 10.1016/j.biopha.2022.114000] [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: 09/05/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/13/2022] Open
Abstract
Cardiovascular disease remains the leading cause of disability and mortality worldwide and a significant global burden. Many lines of evidence suggest complex remodeling responses to cardiovascular disease, such as myocardial ischemia, hypertension and valve disease, which lead to poor clinical outcomes, including heart failure, arrhythmia and sudden cardiac death (SCD). The mechanisms underlying cardiac remodeling are closely related to reactive oxygen species (ROS) and inflammation. Myeloid differentiation protein 1 (MD1) is a secreted glycoprotein known as lymphocyte antigen 86. The complex of MD1 and radioprotective 105 (RP105) is an important regulator of inflammation and is involved in the modulation of vascular remodeling and atherosclerotic plaque development. A recent study suggested that the expression of MD1 in hypertrophic cardiomyopathy (HCM) patients is decreased compared with that in donor hearts. Therefore, MD1 may play an important role in the pathological processes of cardiovascular disease and have potential clinical value. Here, this review aims to discuss the current knowledge regarding the role of MD1 in the regulation of cardiac pathophysiology.
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Affiliation(s)
- Xiaobo Jiang
- Geriatric Diseases Institute of Chengdu, Department of Cardiology, Chengdu Fifth People's Hospital, Chengdu 611137, China; The Second Clinical Medical College, Affiliated Fifth People's Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Peng Ning
- The Second Clinical Medical College, Affiliated Fifth People's Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China; Geriatric Diseases Institute of Chengdu, Department of Endocrinology, Chengdu Fifth People's Hospital, Chengdu 611137, China.
| | - Fang Yan
- Geriatric Department, Chengdu Fifth People's Hospital, Chengdu 611137, China; Center for Medicine Research and Translation, Chengdu Fifth People's Hospital, Chengdu 611137, China.
| | - Jianfeng Wang
- Geriatric Diseases Institute of Chengdu, Department of Cardiology, Chengdu Fifth People's Hospital, Chengdu 611137, China; The Second Clinical Medical College, Affiliated Fifth People's Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Wei Cai
- Geriatric Diseases Institute of Chengdu, Department of Cardiology, Chengdu Fifth People's Hospital, Chengdu 611137, China; The Second Clinical Medical College, Affiliated Fifth People's Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Fan Yang
- The Second Clinical Medical College, Affiliated Fifth People's Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China; Geriatric Diseases Institute of Chengdu, Department of Endocrinology, Chengdu Fifth People's Hospital, Chengdu 611137, China.
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16
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Holmes M, Hurley ME, Sheard TMD, Benson AP, Jayasinghe I, Colman MA. Increased SERCA2a sub-cellular heterogeneity in right-ventricular heart failure inhibits excitation-contraction coupling and modulates arrhythmogenic dynamics. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210317. [PMID: 36189801 PMCID: PMC9527927 DOI: 10.1098/rstb.2021.0317] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/21/2021] [Indexed: 12/14/2022] Open
Abstract
The intracellular calcium handling system of cardiomyocytes is responsible for controlling excitation-contraction coupling (ECC) and has been linked to pro-arrhythmogenic cellular phenomena in conditions such as heart failure (HF). SERCA2a, responsible for intracellular uptake, is a primary regulator of calcium homeostasis, and remodelling of its function has been proposed as a causal factor underlying cellular and tissue dysfunction in disease. Whereas adaptations to the global (i.e. whole-cell) expression of SERCA2a have been previously investigated in the context of multiple diseases, the role of its spatial profile in the sub-cellular volume has yet to be elucidated. We present an approach to characterize the sub-cellular heterogeneity of SERCA2a and apply this approach to quantify adaptations to the length-scale of heterogeneity (the distance over which expression is correlated) associated with right-ventricular (RV)-HF. These characterizations informed simulations to predict the functional implications of this heterogeneity, and its remodelling in disease, on ECC, the dynamics of calcium-transient alternans and the emergence of spontaneous triggered activity. Image analysis reveals that RV-HF is associated with an increase in length-scale and its inter-cellular variability; simulations predict that this increase in length-scale can reduce ECC and critically modulate the vulnerability to both alternans and triggered activity. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- M. Holmes
- Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - M. E. Hurley
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - T. M. D. Sheard
- School of Biosciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - A. P. Benson
- Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK
| | - I. Jayasinghe
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Biosciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - M. A. Colman
- Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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17
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Qu Z, Yan D, Song Z. Modeling Calcium Cycling in the Heart: Progress, Pitfalls, and Challenges. Biomolecules 2022; 12:1686. [PMID: 36421700 PMCID: PMC9687412 DOI: 10.3390/biom12111686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Intracellular calcium (Ca) cycling in the heart plays key roles in excitation-contraction coupling and arrhythmogenesis. In cardiac myocytes, the Ca release channels, i.e., the ryanodine receptors (RyRs), are clustered in the sarcoplasmic reticulum membrane, forming Ca release units (CRUs). The RyRs in a CRU act collectively to give rise to discrete Ca release events, called Ca sparks. A cell contains hundreds to thousands of CRUs, diffusively coupled via Ca to form a CRU network. A rich spectrum of spatiotemporal Ca dynamics is observed in cardiac myocytes, including Ca sparks, spark clusters, mini-waves, persistent whole-cell waves, and oscillations. Models of different temporal and spatial scales have been developed to investigate these dynamics. Due to the complexities of the CRU network and the spatiotemporal Ca dynamics, it is challenging to model the Ca cycling dynamics in the cardiac system, particularly at the tissue sales. In this article, we review the progress of modeling of Ca cycling in cardiac systems from single RyRs to the tissue scale, the pros and cons of the current models and different modeling approaches, and the challenges to be tackled in the future.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, A2-237 CHS, 650 Charles E. Young Drive South, Los Angeles, CA 90095, USA
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Dasen Yan
- Peng Cheng Laboratory, Shenzhen 518066, China
| | - Zhen Song
- Peng Cheng Laboratory, Shenzhen 518066, China
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18
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Chai-Hu-San-Shen Capsule Ameliorates Ventricular Arrhythmia Through Inhibition of the CaMKII/FKBP12.6/RyR2/Ca 2+ Signaling Pathway in Rats with Myocardial Ischemia. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2022; 2022:2670473. [PMID: 36225189 PMCID: PMC9550443 DOI: 10.1155/2022/2670473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/18/2022] [Indexed: 11/18/2022]
Abstract
Ventricular arrhythmia is one of the main causes of sudden cardiac death, especially after myocardial ischemia. Previous studies have shown that Chai-Hu-San-Shen capsule (CHSSC) can reduce the incidence of ventricular arrhythmias following myocardial ischemia, however, the mechanisms of it are unclear. In present study, we explored the mechanism of CHSSC ameliorates ventricular arrhythmia following myocardial ischemia via inhibiting the CaMKII/FKBP12.6/RyR2/Ca2+ signaling pathway. In vivo, a myocardial ischemia rat model was established and treated with CHSSC to evaluate the therapeutic effect of CHSSC. In vitro, we established an ischemia model in H9C2 cells and treated with CHSSC, KN-93, or H-89. Then, intracellular Ca2+ content, the expression of RyR2, and the interaction between FKBP12.6 and RyR2 were detected. The results showed that CHSSC could delay the occurrence of ventricular arrhythmias and shorten the duration of ventricular arrhythmias. After myocardial ischemia, the intracellular Ca2+ content was increased, and CHSSC treatment mitigated this increase, down-regulated the levels of p-CaMKII, CaMKII, p-RyR2, and RyR2, and up-regulated the levels of p-RyR2 (Ser2808) and p-RyR2 (Ser2814). Co-immunoprecipitation showed an interaction between FKBP12.6 and RyR2, and CHSSC up-regulated the content of the FKBP12.6-RyR2 complex in ischemic cells. In conclusion, our study showed that CaMKII activation led to hyperphosphorylation of RyR2 (Ser2814) and RyR2 (Ser2808) during cardiomyocyte ischemia, which resulted in dissociation of the FKBP12.6-RyR2 complex, and increased intracellular Ca2+ content, which may contribute to the development of ventricular arrhythmias. CHSSC may reduce the incidence of ventricular arrhythmias following myocardial ischemia through inhibition of the CaMKII/RyR2/FKBP12.6/Ca2+ signaling pathway.
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19
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Qu Z, Liu MB, Olcese R, Karagueuzian H, Garfinkel A, Chen PS, Weiss JN. R-on-T and the initiation of reentry revisited: Integrating old and new concepts. Heart Rhythm 2022; 19:1369-1383. [PMID: 35364332 PMCID: PMC11334931 DOI: 10.1016/j.hrthm.2022.03.1224] [Citation(s) in RCA: 2] [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: 01/20/2022] [Revised: 03/11/2022] [Accepted: 03/23/2022] [Indexed: 12/29/2022]
Abstract
Initiation of reentry requires 2 factors: (1) a triggering event, most commonly focal excitations such as premature ventricular complexes (PVCs); and (2) a vulnerable substrate with regional dispersion of refractoriness and/or excitability, such as occurs during the T wave of the electrocardiogram when some areas of the ventricle have repolarized and recovered excitability but others have not. When the R wave of a PVC coincides in time with the T wave of the previous beat, this timing can lead to unidirectional block and initiation of reentry, known as the R-on-T phenomenon. Classically, the PVC triggering reentry has been viewed as arising focally from 1 region and propagating into another region whose recovery is delayed, resulting in unidirectional conduction block and reentry initiation. However, more recent evidence indicates that PVCs also can arise from the T wave itself. In the latter case, the PVC initiating reentry is not a separate event from the T wave but rather is causally generated from the repolarization gradient that manifests as the T wave. We call the former an "R-to-T" mechanism and the latter an "R-from-T" mechanism, which are initiation mechanisms distinct from each other. Both are important components of the R-on-T phenomenon and need to be taken into account when designing antiarrhythmic strategies. Strategies targeting suppression of triggers alone or vulnerable substrate alone may be appropriate in some instances but not in others. Preventing R-from-T arrhythmias requires suppressing the underlying dynamic tissue instabilities responsible for producing both triggers and substrate vulnerability simultaneously. The same principles are likely to apply to supraventricular arrhythmias.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California.
| | - Michael B Liu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Riccardo Olcese
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Hrayr Karagueuzian
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Alan Garfinkel
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Integrative Biology and Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Peng-Sheng Chen
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - James N Weiss
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California
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20
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Arsenos P, Gatzoulis KA, Tsiachris D, Dilaveris P, Sideris S, Sotiropoulos I, Archontakis S, Antoniou CK, Kordalis A, Skiadas I, Toutouzas K, Vlachopoulos C, Tousoulis D, Tsioufis K. Arrhythmic risk stratification in ischemic, non-ischemic and hypertrophic cardiomyopathy: A two-step multifactorial, electrophysiology study inclusive approach. World J Cardiol 2022; 14:139-151. [PMID: 35432775 PMCID: PMC8968455 DOI: 10.4330/wjc.v14.i3.139] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 10/28/2021] [Accepted: 02/23/2022] [Indexed: 02/06/2023] Open
Abstract
Annual arrhythmic sudden cardiac death ranges from 0.6% to 4% in ischemic cardiomyopathy (ICM), 1% to 2% in non-ischemic cardiomyopathy (NICM), and 1% in hypertrophic cardiomyopathy (HCM). Towards a more effective arrhythmic risk stratification (ARS) we hereby present a two-step ARS with the usage of seven non-invasive risk factors: Late potentials presence (≥ 2/3 positive criteria), premature ventricular contractions (≥ 30/h), non-sustained ventricular tachycardia (≥ 1episode/24 h), abnormal heart rate turbulence (onset ≥ 0% and slope ≤ 2.5 ms) and reduced deceleration capacity (≤ 4.5 ms), abnormal T wave alternans (≥ 65μV), decreased heart rate variability (SDNN < 70ms), and prolonged QTc interval (> 440 ms in males and > 450 ms in females) which reflect the arrhythmogenic mechanisms for the selection of the intermediate arrhythmic risk patients in the first step. In the second step, these intermediate-risk patients undergo a programmed ventricular stimulation (PVS) for the detection of inducible, truly high-risk ICM and NICM patients, who will benefit from an implantable cardioverter defibrillator. For HCM patients, we also suggest the incorporation of the PVS either for the low HCM Risk-score patients or for the patients with one traditional risk factor in order to improve the inadequate sensitivity of the former and the low specificity of the latter.
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Affiliation(s)
- Petros Arsenos
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Konstantinos A Gatzoulis
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | | | - Polychronis Dilaveris
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Skevos Sideris
- Department of Cardiology, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Ilias Sotiropoulos
- Department of Cardiology, Hippokration Hospital, Athens 11527, Attika, Greece
| | | | | | - Athanasios Kordalis
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Ioannis Skiadas
- Fifth Department of Cardiology, Hygeia Hospital, Marousi 15123, Attika, Greece
| | - Konstantinos Toutouzas
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Charalambos Vlachopoulos
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Dimitrios Tousoulis
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
| | - Konstantinos Tsioufis
- First Department of Cardiology, National and Kapodistrian University of Athens, Hippokration Hospital, Athens 11527, Attika, Greece
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21
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Affiliation(s)
- Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California.
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22
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Zhang Z, Chen PS, Weiss JN, Qu Z. Why Is Only Type 1 Electrocardiogram Diagnostic of Brugada Syndrome? Mechanistic Insights From Computer Modeling. Circ Arrhythm Electrophysiol 2022; 15:e010365. [PMID: 34963310 PMCID: PMC8766947 DOI: 10.1161/circep.121.010365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Three types of characteristic ST-segment elevation are associated with Brugada syndrome but only type 1 is diagnostic. Why only type 1 ECG is diagnostic remains unanswered. METHODS Computer simulations were performed in single cells, 1-dimensional cables, and 2-dimensional tissues to investigate the effects of the peak and late components of the transient outward potassium current (Ito), sodium current, and L-type calcium current (ICa,L) as well as other potassium currents on the genesis of ECG morphologies and phase 2 reentry (P2R). RESULTS Although a sufficiently large peak Ito was required to result in the type 1 ECG pattern and P2R, increasing the late component of Ito converted type 1 ECG to type 2 ECG and suppressed P2R. Increasing the peak Ito promoted spiral wave breakup, potentiating the transition from tachycardia to fibrillation, but increasing the late Ito prevented spiral wave breakup by flattening the action potential duration restitution and preventing P2R. A sufficiently large ICa,L conductance was needed for P2R to occur, but once above the critical conductance, blocking ICa,L promoted P2R. However, selectively blocking the window and late components of ICa,L suppressed P2R, countering the effect of the late Ito. Blocking either the peak or late components of sodium current promoted P2R, with the late sodium current blockade having the larger effect. As expected, increasing other potassium currents potentiated P2R, with ATP-sensitive potassium current exhibiting a larger effect than rapid and slow component of the delayed rectifier potassium current. CONCLUSIONS The peak Ito promotes type 1 ECG and P2R, whereas the late Ito converts type 1 ECG to type 2 ECG and suppresses P2R. Blocking the peak ICa,L and either the peak or the late sodium current promotes P2R, whereas blocking the window and late ICa,L suppresses P2R. These results provide important insights into the mechanisms of arrhythmogenesis and potential therapeutic targets for treatment of Brugada syndrome. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Zhaoyang Zhang
- Department of physics, School of Physical Science and Technology, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Peng-Sheng Chen
- Department of Cardiology, Cedars Sinai Medical Center, Los Aneles, CA 90048, USA
| | - James N. Weiss
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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23
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Guryanov MI, Pusev RS, Guryanova NM, Kharitonova EA, Yablonsky PK. Organized Structure of Ventricular Fibrillation during Prolonged Heart Perfusion in Dogs. Sovrem Tekhnologii Med 2021; 12:26-30. [PMID: 34795976 PMCID: PMC8596255 DOI: 10.17691/stm2020.12.3.03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Indexed: 11/14/2022] Open
Abstract
The aim of the study was to identify the organized ventricular fibrillation (VF) activity in the dog heart and characterize its quantitative parameters during prolonged heart perfusion.
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Affiliation(s)
- M I Guryanov
- Professor, Department of Basic and Specific Medical Sciences, Faculty of Medicine; Saint Petersburg State University, 79 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russia
| | - R S Pusev
- Associate Professor, Department of Informatics, Saint Petersburg School of Physics, Mathematics, and Computer Science; National Research University Higher School of Economics, 16 Soyuza Pechatnikov St., Saint Petersburg, 199008, Russia
| | - N M Guryanova
- PhD Student, Department of Pharmacology, Faculty of Medicine; Saint Petersburg State University, 79 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russia
| | - E A Kharitonova
- Associate Professor, Department of Basic and Specific Medical Sciences, Faculty of Medicine; Saint Petersburg State University, 79 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russia
| | - P K Yablonsky
- Professor, Director; Saint Petersburg Research Institute of Phthisiopulmonology, Ministry of Health the Russian Federation, 24 Ligovsky Avenue, Saint Petersburg, 191036, Russia; Head of the Department of Hospital Surgery; Saint Petersburg State University, 7-9 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russia; Dean of the Faculty of Medicine; Saint Petersburg State University, 79 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russia
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24
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Morotti S, Liu C, Hegyi B, Ni H, Fogli Iseppe A, Wang L, Pritoni M, Ripplinger CM, Bers DM, Edwards AG, Grandi E. Quantitative cross-species translators of cardiac myocyte electrophysiology: Model training, experimental validation, and applications. SCIENCE ADVANCES 2021; 7:eabg0927. [PMID: 34788089 PMCID: PMC8598003 DOI: 10.1126/sciadv.abg0927] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 09/28/2021] [Indexed: 05/13/2023]
Abstract
Animal experimentation is key in the evaluation of cardiac efficacy and safety of novel therapeutic compounds. However, interspecies differences in the mechanisms regulating excitation-contraction coupling can limit the translation of experimental findings from animal models to human physiology and undermine the assessment of drugs’ efficacy and safety. Here, we built a suite of translators for quantitatively mapping electrophysiological responses in ventricular myocytes across species. We trained these statistical operators using a broad dataset obtained by simulating populations of our biophysically detailed computational models of action potential and Ca2+ transient in mouse, rabbit, and human. We then tested our translators against experimental data describing the response to stimuli, such as ion channel block, change in beating rate, and β-adrenergic challenge. We demonstrate that this approach is well suited to predicting the effects of perturbations across different species or experimental conditions and suggest its integration into mechanistic studies and drug development pipelines.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Haibo Ni
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Alex Fogli Iseppe
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Lianguo Wang
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Marco Pritoni
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Andrew G. Edwards
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
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25
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Huang SY, Chen YC, Kao YH, Lu YY, Lin YK, Higa S, Chen SA, Chen YJ. Calcium dysregulation increases right ventricular outflow tract arrhythmogenesis in rabbit model of chronic kidney disease. J Cell Mol Med 2021; 25:11264-11277. [PMID: 34761510 PMCID: PMC8650029 DOI: 10.1111/jcmm.17052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 10/24/2021] [Accepted: 11/01/2021] [Indexed: 12/03/2022] Open
Abstract
Chronic kidney disease (CKD) increases the risk of arrhythmia. The right ventricular outflow tract (RVOT) is a crucial site of ventricular tachycardia (VT) origination. We hypothesize that CKD increases RVOT arrhythmogenesis through its effects on calcium dysregulation. We analysed measurements obtained using conventional microelectrodes, patch clamp, confocal microscopy, western blotting, immunohistochemical examination and lipid peroxidation for both control and CKD (induced by 150 mg/kg neomycin and 500 mg/kg cefazolin daily) rabbit RVOT tissues or cardiomyocytes. The RVOT of CKD rabbits exhibited a short action potential duration, high incidence of tachypacing (20 Hz)‐induced sustained VT, and long duration of isoproterenol and tachypacing‐induced sustained and non‐sustained VT. Tachypacing‐induced sustained and non‐sustained VT in isoproterenol‐treated CKD RVOT tissues were attenuated by KB‐R7943 and partially inhibited by KN93 and H89. The CKD RVOT myocytes had high levels of phosphorylated CaMKII and PKA, and an increased expression of tyrosine hydroxylase‐positive neural density. The CKD RVOT myocytes exhibited large levels of Ito, IKr, NCX and L‐type calcium currents, calcium leak and malondialdehyde but low sodium current, SERCA2a activity and SR calcium content. The RVOT in CKD with oxidative stress and autonomic neuron hyperactivity exhibited calcium handling abnormalities, which contributed to the induction of VT.
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Affiliation(s)
- Shih-Yu Huang
- Division of Cardiac Electrophysiology, Cardiovascular Center, Cathay General Hospital, Taipei City, Taiwan.,School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei City, Taiwan
| | - Yu-Hsun Kao
- Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei City, Taiwan.,Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei City, Taiwan
| | - Yen-Yu Lu
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Division of Cardiology, Department of Internal Medicine, Sijhih Cathay General Hospital, New Taipei City, Taiwan
| | - Yung-Kuo Lin
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei City, Taiwan.,Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei City, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Urasoe, Japan
| | - Shih-Ann Chen
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei City, Taiwan.,Cardiovascular Center, Taichung Veterans General Hospital, Taichung City, 40705, Taiwan
| | - Yi-Jen Chen
- Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei City, Taiwan.,Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei City, Taiwan.,Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei City, Taiwan.,Cardiovascular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei City, Taiwan
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26
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Oknińska M, Paterek A, Zambrowska Z, Mackiewicz U, Mączewski M. Effect of Ivabradine on Cardiac Ventricular Arrhythmias: Friend or Foe? J Clin Med 2021; 10:4732. [PMID: 34682854 PMCID: PMC8537674 DOI: 10.3390/jcm10204732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/24/2021] [Accepted: 10/08/2021] [Indexed: 12/12/2022] Open
Abstract
Life-threatening ventricular arrhythmias, such as ventricular tachycardia and ventricular fibrillation remain an ongoing clinical problem and their prevention and treatment require optimization. Conventional antiarrhythmic drugs are associated with significant proarrhythmic effects that often outweigh their benefits. Another option, the implantable cardioverter defibrillator, though clearly the primary therapy for patients at high risk of ventricular arrhythmias, is costly, invasive, and requires regular monitoring. Thus there is a clear need for new antiarrhythmic treatment strategies. Ivabradine, a heartrate-reducing agent, an inhibitor of HCN channels, may be one of such options. In this review we discuss emerging data from experimental studies that indicate new mechanism of action of this drug and further areas of investigation and potential use of ivabradine as an antiarrhythmic agent. However, clinical evidence is limited, and the jury is still out on effects of ivabradine on cardiac ventricular arrhythmias in the clinical setting.
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Affiliation(s)
| | | | | | | | - Michał Mączewski
- Centre of Postgraduate Medical Education, Department of Clinical Physiology, ul. Marymoncka 99/103, 01-813 Warsaw, Poland; (M.O.); (A.P.); (Z.Z.); (U.M.)
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27
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Zhang Z, Qu Z. Life and death saddles in the heart. Phys Rev E 2021; 103:062406. [PMID: 34271754 PMCID: PMC10066710 DOI: 10.1103/physreve.103.062406] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 05/25/2021] [Indexed: 11/07/2022]
Abstract
Saddle points are responsible for threshold phenomena of many biological systems. In the heart, saddle points determine the normal excitability and conduction, but are also responsible for certain abnormal action potential behaviors associated with lethal arrhythmias. We investigate the dynamical mechanisms for the genesis of lethal extra heartbeats in heterogeneous cardiac tissue under two diseased conditions. For both conditions, the lethal events occur when the system is close to the saddle point, implying the pivotal role of the saddle point in cardiac arrhythmogenesis.
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Affiliation(s)
- Zhaoyang Zhang
- Department of Medicine, University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine, University of California, Los Angeles, California 90095, USA.,Department of Computational Medicine, University of California, Los Angeles, California 90095, USA
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28
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Barrio R, Martínez MÁ, Pueyo E, Serrano S. Dynamical analysis of early afterdepolarization patterns in a biophysically detailed cardiac model. CHAOS (WOODBURY, N.Y.) 2021; 31:073137. [PMID: 34340346 DOI: 10.1063/5.0055965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Arrhythmogenic early afterdepolarizations (EADs) are investigated in a biophysically detailed mathematical model of a rabbit ventricular myocyte, providing their location in the parameter phase space and describing their dynamical mechanisms. Simulations using the Sato model, defined by 27 state variables and 177 parameters, are conducted to generate electrical action potentials (APs) for different values of the pacing cycle length and other parameters related to sodium and calcium concentrations. A detailed study of the different AP patterns with or without EADs is carried out, showing the presence of a high variety of temporal AP configurations with chaotic and quasiperiodic behaviors. Regions of bistability are identified and, importantly, linked to transitions between different behaviors. Using sweeping techniques, one-, two-, and three-parameter phase spaces are provided, allowing ascertainment of the role of the selected parameters as well as location of the transition regions. A Devil's staircase, with symbolic sequence analysis, is proposed to describe transitions in the ratio between the number of voltage (EAD and AP) peaks and the number of APs. To conclude, the obtained results are linked to recent studies for low-dimensional models and a conjecture is made for the internal dynamical structure of the transition region from non-EAD to EAD behavior using fold and cusp bifurcations and maximal canards.
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Affiliation(s)
- Roberto Barrio
- Department of Applied Mathematics and IUMA, Computational Dynamics Group, University of Zaragoza, E-50009 Zaragoza, Spain
| | - M Ángeles Martínez
- Department of Applied Mathematics and IUMA, Computational Dynamics Group, University of Zaragoza, E-50009 Zaragoza, Spain
| | - Esther Pueyo
- I3A, University of Zaragoza, IIS Aragón and CIBER-BBN, E-50018 Zaragoza, Spain
| | - Sergio Serrano
- Department of Applied Mathematics and IUMA, Computational Dynamics Group, University of Zaragoza, E-50009 Zaragoza, Spain
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29
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Cha MJ, Seo JW, Kim HJ, Kim MK, Yoon HS, Jo SW, Oh S, Chang JH. Early Changes in Rat Heart After High-Dose Irradiation: Implications for Antiarrhythmic Effects of Cardiac Radioablation. J Am Heart Assoc 2021; 10:e019072. [PMID: 33660526 PMCID: PMC8174197 DOI: 10.1161/jaha.120.019072] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Background Noninvasive cardiac radioablation is employed to treat ventricular arrhythmia. However, myocardial changes leading to early‐period antiarrhythmic effects induced by high‐dose irradiation are unknown. This study investigated dose‐responsive histologic, ultrastructural, and functional changes within 1 month after irradiation in rat heart. Methods and Results Whole hearts of wild‐type Lewis rats (N=95) were irradiated with single fraction 20, 25, 30, 40, or 50 Gy and explanted at 1 day or 1, 2, 3, or 4 weeks’ postirradiation. Microscopic pathologic changes of cardiac structures by light microscope with immunohistopathologic staining, ultrastructure by electron microscopy, and functional evaluation by ECG and echocardiography were studied. Despite high‐dose irradiation, no myocardial necrosis and apoptosis were observed. Intercalated discs were widened and disrupted, forming uneven and twisted junctions between adjacent myocytes. Diffuse vacuolization peaked at 3 weeks, suggesting irradiation dose‐responsiveness, which was correlated with interstitial and intracellular edema. CD68 immunostaining accompanying vacuolization suggested mononuclear cell infiltration. These changes were prominent in working myocardium but not cardiac conduction tissue. Intracardiac conduction represented by PR and QTc intervals on ECG was delayed compared with baseline measurements. ST segment was initially depressed and gradually elevated. Ventricular chamber dimensions and function remained intact without pericardial effusion. Conclusions Mononuclear cell–related intracellular and extracellular edema with diffuse vacuolization and intercalated disc widening were observed within 1 month after high‐dose irradiation. ECG indicated intracardiac conduction delay with prominent ST‐segment changes. These observations suggest that early antiarrhythmic effects after cardiac radioablation result from conduction disturbances and membrane potential alterations without necrosis.
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Affiliation(s)
- Myung-Jin Cha
- Division of Cardiology Department of Internal Medicine Seoul National University Hospital Seoul South Korea
| | - Jeong-Wook Seo
- Departments of Pathology Seoul National University Hospital Seoul South Korea
| | - Hak Jae Kim
- Department of Radiation Oncology Seoul National University College of Medicine Seoul Korea.,Department of Radiation Oncology Seoul National University Hospital Seoul South Korea.,Cancer Research InstituteSeoul National University College of Medicine Seoul Korea
| | - Moo-Kang Kim
- Division of Cardiology Department of Internal Medicine Seoul National University Hospital Seoul South Korea
| | - Hye-Sun Yoon
- Division of Cardiology Department of Internal Medicine Seoul National University Hospital Seoul South Korea
| | - Seong Won Jo
- Seoul National University College of Medicine Seoul Korea
| | - Seil Oh
- Division of Cardiology Department of Internal Medicine Seoul National University Hospital Seoul South Korea
| | - Ji Hyun Chang
- Department of Radiation Oncology Seoul National University College of Medicine Seoul Korea.,Department of Radiation Oncology Seoul National University Hospital Seoul South Korea
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30
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Landaw J, Yuan X, Chen PS, Qu Z. The transient outward potassium current plays a key role in spiral wave breakup in ventricular tissue. Am J Physiol Heart Circ Physiol 2021; 320:H826-H837. [PMID: 33385322 PMCID: PMC8082802 DOI: 10.1152/ajpheart.00608.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 11/22/2022]
Abstract
Spiral wave reentry as a mechanism of lethal ventricular arrhythmias has been widely demonstrated in animal experiments and recordings from human hearts. It has been shown that in structurally normal hearts spiral waves are unstable, breaking up into multiple wavelets via dynamical instabilities. However, many of the second-generation action potential models give rise only to stable spiral waves, raising issues regarding the underlying mechanisms of spiral wave breakup. In this study, we carried out computer simulations of two-dimensional homogeneous tissues using five ventricular action potential models. We show that the transient outward potassium current (Ito), although it is not required, plays a key role in promoting spiral wave breakup in all five models. As the maximum conductance of Ito increases, it first promotes spiral wave breakup and then stabilizes the spiral waves. In the absence of Ito, speeding up the L-type calcium kinetics can prevent spiral wave breakup, however, with the same speedup kinetics, spiral wave breakup can be promoted by increasing Ito. Increasing Ito promotes single-cell dynamical instabilities, including action potential duration alternans and chaos, and increasing Ito further suppresses these action potential dynamics. These cellular properties agree with the observation that increasing Ito first promotes spiral wave breakup and then stabilizes spiral waves in tissue. Implications of our observations to spiral wave dynamics in the real hearts and action potential model improvements are discussed.NEW & NOTEWORTHY Spiral wave breakup manifesting as multiple wavelets is a mechanism of ventricular fibrillation. It has been known that spiral wave breakup in cardiac tissue can be caused by a steeply sloped action potential duration restitution curve, a property mainly determined by the recovery of L-type calcium current. Here, we show that the transient outward potassium current (Ito) is another current that plays a key role in spiral wave breakup, that is, spiral waves can be stable for low and high maximum Ito conductance but breakup occurs for intermediate maximum Ito conductance. Since Ito is present in normal hearts of many species and required for Brugada syndrome, it may play an important role in the spiral wave stability and arrhythmogenesis under both normal condition and Brugada syndrome.
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Affiliation(s)
- Julian Landaw
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xiaoping Yuan
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Information Engineering School, Hangzhou Dianzi University, Hangzhou, People's Republic of China
| | | | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
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31
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JIN LIAN, HUANG YANQI, ZHU HONGLEI, GENG ZIHUI, WU XIAOMEI. KEY FACTORS TO THE RATE DEPENDENCE OF EARLY AFTERDEPOLARIZATIONS: A SIMULATION STUDY. J MECH MED BIOL 2021. [DOI: 10.1142/s0219519421500020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Early afterdepolarizations (EADs) in cardiac myocytes have been reported to be associated with a series of cardiac arrhythmias. The generation of EADs has a high correlation with the excitation period, leading to repolarization dispersion over the cardiac tissue. However, the mechanism of EAD rate dependence has not been thoroughly revealed. In this study, the simulation approach was used to investigate the mechanism underlying EAD rate dependence. The results indicated that the gating variable of the delayed rectifier potassium current ([Formula: see text]-gate) and the intracellular sodium ion concentration ([Na[Formula: see text]][Formula: see text] were key factors contributing to EAD rate dependence. Also, different mathematical models showed different types of EAD rate dependence, which needs to be considered in the future simulation research related to EADs.
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Affiliation(s)
- LIAN JIN
- Electronic Engineering Department, Fudan University, 220 Handan Road Shanghai 200433, P. R. China
| | - YANQI HUANG
- Electronic Engineering Department, Fudan University, 220 Handan Road Shanghai 200433, P. R. China
| | - HONGLEI ZHU
- Electronic Engineering Department, Fudan University, 220 Handan Road Shanghai 200433, P. R. China
| | - ZIHUI GENG
- Electronic Engineering Department, Fudan University, 220 Handan Road Shanghai 200433, P. R. China
| | - XIAOMEI WU
- Electronic Engineering Department, Fudan University, 220 Handan Road Shanghai 200433, P. R. China
- Shanghai Engineering Research Center of Assistive Devices, 220 Handan Road, Shanghai 200433, P. R. China
- Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, 220 Handan Road, Shanghai 200433, P. R. China
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32
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Mortensen P, Gao H, Smith G, Simitev RD. Action potential propagation and block in a model of atrial tissue with myocyte-fibroblast coupling. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2021; 38:106-131. [PMID: 33412587 DOI: 10.1093/imammb/dqaa014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/20/2020] [Accepted: 12/08/2020] [Indexed: 02/07/2023]
Abstract
The electrical coupling between myocytes and fibroblasts and the spacial distribution of fibroblasts within myocardial tissues are significant factors in triggering and sustaining cardiac arrhythmias, but their roles are poorly understood. This article describes both direct numerical simulations and an asymptotic theory of propagation and block of electrical excitation in a model of atrial tissue with myocyte-fibroblast coupling. In particular, three idealized fibroblast distributions are introduced: uniform distribution, fibroblast barrier and myocyte strait-all believed to be constituent blocks of realistic fibroblast distributions. Primary action potential biomarkers including conduction velocity, peak potential and triangulation index are estimated from direct simulations in all cases. Propagation block is found to occur at certain critical values of the parameters defining each idealized fibroblast distribution, and these critical values are accurately determined. An asymptotic theory proposed earlier is extended and applied to the case of a uniform fibroblast distribution. Biomarker values are obtained from hybrid analytical-numerical solutions of coupled fast-time and slow-time periodic boundary value problems and compare well to direct numerical simulations. The boundary of absolute refractoriness is determined solely by the fast-time problem and is found to depend on the values of the myocyte potential and on the slow inactivation variable of the sodium current ahead of the propagating pulse. In turn, these quantities are estimated from the slow-time problem using a regular perturbation expansion to find the steady state of the coupled myocyte-fibroblast kinetics. The asymptotic theory gives a simple analytical expression that captures with remarkable accuracy the block of propagation in the presence of fibroblasts.
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Affiliation(s)
- Peter Mortensen
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK, and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow G12 8TA, UK
| | - Hao Gao
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - Godfrey Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow G12 8TA, UK
| | - Radostin D Simitev
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
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33
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Marchena M, Echebarria B, Shiferaw Y, Alvarez-Lacalle E. Buffering and total calcium levels determine the presence of oscillatory regimes in cardiac cells. PLoS Comput Biol 2020; 16:e1007728. [PMID: 32970668 PMCID: PMC7537911 DOI: 10.1371/journal.pcbi.1007728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 10/06/2020] [Accepted: 07/07/2020] [Indexed: 12/16/2022] Open
Abstract
Calcium oscillations and waves induce depolarization in cardiac cells which are believed to cause life-threathening arrhythimas. In this work, we study the conditions for the appearance of calcium oscillations in both a detailed subcellular model of calcium dynamics and a minimal model that takes into account just the minimal ingredients of the calcium toolkit. To avoid the effects of homeostatic changes and the interaction with the action potential we consider the somewhat artificial condition of a cell without pacing and with no calcium exchange with the extracellular medium. Both the full subcellular model and the minimal model present the same scenarios depending on the calcium load: two stationary states, one with closed ryanodine receptors (RyR) and most calcium in the cell stored in the sarcoplasmic reticulum (SR), and another, with open RyRs and a depleted SR. In between, calcium oscillations may appear. The robustness of these oscillations is determined by the amount of calsequestrin (CSQ). The lack of this buffer in the SR enhances the appearance of oscillations. The minimal model allows us to relate the stability of the oscillating state to the nullcline structure of the system, and find that its range of existence is bounded by a homoclinic and a Hopf bifurcation, resulting in a sudden transition to the oscillatory regime as the cell calcium load is increased. Adding a small amount of noise to the RyR behavior increases the parameter region where oscillations appear and provides a gradual transition from the resting state to the oscillatory regime, as observed in the subcellular model and experimentally. In cardiac cells, calcium plays a very important role. An increase in calcium levels is the trigger used by the cell to initiate contraction. Besides, calcium modulates several transmembrane currents, affecting the cell transmembrane potential. Thus, dysregulations in calcium handling have been associated with the appearance of arrhythmias. Often, this dysregulation results in the appearance of periodic calcium waves or global oscillations, providing a pro-arrhythmic substrate. In this paper, we study the onset of calcium oscillations in cardiac cells using both a detailed subcellular model of calcium dynamics and a minimal model that takes into account the essential ingredients of the calcium toolkit. Both reproduce the main experimental results and link this behavior with the presence of different steady-state solutions and bifurcations that depend on the total amount of calcium in the cell and in the level of buffering present. We expect that this work will help to clarify the conditions under which calcium oscillations appear in cardiac myocytes and, therefore, will represent a step further in the understanding of the origin of cardiac arrhythmias.
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Affiliation(s)
- Miquel Marchena
- Departament de Física, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Blas Echebarria
- Departament de Física, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona, Spain
| | - Yohannes Shiferaw
- Physics Department, California State University, Northridge, California 91330, USA
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34
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Marciszek M, Paterek A, Oknińska M, Mackiewicz U, Mączewski M. Ivabradine is as effective as metoprolol in the prevention of ventricular arrhythmias in acute non-reperfused myocardial infarction in the rat. Sci Rep 2020; 10:15027. [PMID: 32929098 PMCID: PMC7490414 DOI: 10.1038/s41598-020-71706-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/29/2020] [Indexed: 12/29/2022] Open
Abstract
Ventricular arrhythmias are a major source of early mortality in acute myocardial infarction (MI) and remain a major therapeutic challenge. Thus we investigated effects of ivabradine, a presumably specific bradycardic agent versus metoprolol, a β-blocker, at doses offering the same heart rate (HR) reduction, on ventricular arrhythmias in the acute non-reperfused MI in the rat. Immediately after MI induction a single dose of ivabradine/ metoprolol was given. ECG was continuously recorded and ventricular arrhythmias were analyzed. After 6 h epicardial monophasic action potentials (MAPs) were recorded and cardiomyocyte Ca2+ handling was assessed. Both ivabradine and metoprolol reduced HR by 17% and arrhythmic mortality (14% and 19%, respectively, versus 33% in MI, p < 0.05) and ventricular arrhythmias in post-MI rats. Both drugs reduced QTc prolongation and decreased sensitivity of ryanodine receptors in isolated cardiomyocytes, but otherwise had no effect on Ca2+ handling, velocity of conduction or repolarization. We did not find any effects of potential IKr inhibition by ivabradine in this setting. Thus Ivabradine is an equally effective antiarrhythmic agent as metoprolol in early MI in the rat. It could be potentially tested as an alternative antiarrhythmic agent in acute MI when β-blockers are contraindicated.
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Affiliation(s)
- Mariusz Marciszek
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Aleksandra Paterek
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Marta Oknińska
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Urszula Mackiewicz
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | - Michał Mączewski
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Warsaw, Poland.
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Rose P, Schleimer JH, Schreiber S. Modifications of sodium channel voltage dependence induce arrhythmia-favouring dynamics of cardiac action potentials. PLoS One 2020; 15:e0236949. [PMID: 32750067 PMCID: PMC7402508 DOI: 10.1371/journal.pone.0236949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/16/2020] [Indexed: 11/19/2022] Open
Abstract
Heart arrhythmia is a pathological condition where the sequence of electrical impulses in the heart deviates from the normal rhythm. It is often associated with specific channelopathies in cardiac tissue, yet how precisely the changes in ionic channels affect the electrical activity of cardiac cells is still an open question. Even though sodium channel mutations that underlie cardiac syndromes like the Long-Q-T and the Brugada-syndrome are known to affect a number of channel parameters simultaneously, previous studies have predominantly focused on the persistent late component of the sodium current as the causal explanation for an increased risk of heart arrhythmias in these cardiac syndromes. A systematic analysis of the impact of other important sodium channel parameters is currently lacking. Here, we investigate the reduced ten-Tusscher-model for single human epicardium ventricle cells and use mathematical bifurcation analysis to predict the dependence of the cardiac action potential on sodium channel activation and inactivation time-constants and voltage dependence. We show that, specifically, shifts of the voltage dependence of activation and inactivation curve can lead to drastic changes in the action potential dynamics, inducing oscillations of the membrane potential as well as bistability. Our results not only demonstrate a new way to induce multiple co-existing states of excitability (biexcitability) but also emphasize the critical role of the voltage dependence of sodium channel activation and inactivation curves for the induction of heart-arrhythmias.
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Affiliation(s)
- Pia Rose
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jan-Hendrik Schleimer
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Susanne Schreiber
- Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
- * E-mail:
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36
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Inanır M, Gunes Y, Sincer I, Erdal E. Evaluation of Electrocardiographic Ventricular Depolarization and Repolarization Variables in Type 1 Diabetes Mellitus. Arq Bras Cardiol 2020; 114:275-280. [PMID: 32215498 PMCID: PMC7077569 DOI: 10.36660/abc.20180343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/10/2019] [Indexed: 12/14/2022] Open
Abstract
Background The risk of cardiovascular events and sudden death increases with type 1 diabetes mellitus (T1DM). Objective To evaluate electrocardiographic markers of arrhythmias in T1DM patients. Methods Electrocardiographic parameters reflecting ventricular depolarization and repolarization, namely, QT, QTc, QTd, QTdc, Tp-e, JT, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios, of 46 patients diagnosed with T1DM were retrospectively analyzed and compared with 46 healthy age-, sex-, and body mass-matched controls. Correlations between T1DM duration, hemoglobin A1c (HbA1c), and ventricular repolarization variables were analyzed. P values lower than 0.05 were considered statistically significant. Results Diabetes duration was 16.6 ± 7.1 years, and HbA1c was 10.81% ± 3.27% in the T1DM group. In comparison with the control group, heart rate, QTc, QTd, QTdc, Tp-e and JTc intervals, Tp-e/QT ratio (p < 0.001), and Tp-e/QTc ratio (p = 0.007) were significantly higher in T1DM patients. T1DM duration and HbA1c levels were significantly correlated with QTc, QTd, QTdc, Tp-e, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios. Conclusions In T1DM patients, potential electrocardiographic repolarization predictors were significantly increased in correlation with disease duration and HbA1c levels. These findings may contribute to the understanding of sudden cardiac death in patients with T1DM.
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Affiliation(s)
- Mehmet Inanır
- Abant Izzet Baysal University Hospital, Bolu - Turkey
| | - Yilmaz Gunes
- Abant Izzet Baysal University Hospital, Bolu - Turkey
| | - Isa Sincer
- Abant Izzet Baysal University Hospital, Bolu - Turkey
| | - Emrah Erdal
- Abant Izzet Baysal University Hospital, Bolu - Turkey
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37
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Kistamás K, Veress R, Horváth B, Bányász T, Nánási PP, Eisner DA. Calcium Handling Defects and Cardiac Arrhythmia Syndromes. Front Pharmacol 2020; 11:72. [PMID: 32161540 PMCID: PMC7052815 DOI: 10.3389/fphar.2020.00072] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/24/2020] [Indexed: 12/13/2022] Open
Abstract
Calcium ions (Ca2+) play a major role in the cardiac excitation-contraction coupling. Intracellular Ca2+ concentration increases during systole and falls in diastole thereby determining cardiac contraction and relaxation. Normal cardiac function also requires perfect organization of the ion currents at the cellular level to drive action potentials and to maintain action potential propagation and electrical homogeneity at the tissue level. Any imbalance in Ca2+ homeostasis of a cardiac myocyte can lead to electrical disturbances. This review aims to discuss cardiac physiology and pathophysiology from the elementary membrane processes that can cause the electrical instability of the ventricular myocytes through intracellular Ca2+ handling maladies to inherited and acquired arrhythmias. Finally, the paper will discuss the current therapeutic approaches targeting cardiac arrhythmias.
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Affiliation(s)
- Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - David A Eisner
- Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
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Huang C, Song Z, Landaw J, Qu Z. Spatially Discordant Repolarization Alternans in the Absence of Conduction Velocity Restitution. Biophys J 2020; 118:2574-2587. [PMID: 32101718 DOI: 10.1016/j.bpj.2020.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/21/2020] [Accepted: 02/06/2020] [Indexed: 01/20/2023] Open
Abstract
Spatially discordant alternans (SDA) of action potential duration (APD) has been widely observed in cardiac tissue and is linked to cardiac arrhythmogenesis. Theoretical studies have shown that conduction velocity restitution (CVR) is required for the formation of SDA. However, this theory is not completely supported by experiments, indicating that other mechanisms may exist. In this study, we carried out computer simulations using mathematical models of action potentials to investigate the mechanisms of SDA in cardiac tissue. We show that when CVR is present and engaged, such as fast pacing from one side of the tissue, the spatial pattern of APD in the tissue undergoes either spatially concordant alternans or SDA, independent of initial conditions or tissue heterogeneities. When CVR is not engaged, such as simultaneous pacing of the whole tissue or under normal/slow heart rates, the spatial pattern of APD in the tissue can have multiple solutions, including spatially concordant alternans and different SDA patterns, depending on heterogeneous initial conditions or pre-existing repolarization heterogeneities. In homogeneous tissue, curved nodal lines are not stable, which either evolve into straight lines or disappear. However, in heterogeneous itssue, curved nodal lines can be stable, depending on their initial locations and shapes relative to the structure of the heterogeneity. Therefore, CVR-induced SDA and non-CVR-induced SDA exhibit different dynamical properties, which may be responsible for the different SDA properties observed in experimental studies and arrhythmogenesis in different clinical settings.
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Affiliation(s)
- Chunli Huang
- Department of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Systems Science, Beijing Normal University, Beijing, China
| | - Zhen Song
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Julian Landaw
- Department of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Computational Medicine, University of California, Los Angeles, Los Angeles, California.
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Ginsenoside Rb1 exerts antiarrhythmic effects by inhibiting I Na and I CaL in rabbit ventricular myocytes. Sci Rep 2019; 9:20425. [PMID: 31892729 PMCID: PMC6938504 DOI: 10.1038/s41598-019-57010-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/19/2019] [Indexed: 12/18/2022] Open
Abstract
Ginsenoside Rb1 exerts its pharmacological action by regulating sodium, potassium and calcium ion channels in the membranes of nerve cells. These ion channels are also present in cardiomyocytes, but no studies have been reported to date regarding the effects of Rb1 on cardiac sodium currents (INa), L-type calcium currents (ICaL) and action potentials (APs). Additionally, the antiarrhythmic potential of Rb1 has not been assessed. In this study, we used a whole-cell patch clamp technique to assess the effect of Rb1 on these ion channels. The results showed that Rb1 inhibited INa and ICaL, reduced the action potential amplitude (APA) and maximum upstroke velocity (Vmax), and shortened the action potential duration (APD) in a concentration-dependent manner but had no effect on the inward rectifier potassium current (IK1), delayed rectifier potassium current (IK) or resting membrane potential (RMP). We also designed a pathological model at the cellular and organ level to verify the role of Rb1. The results showed that Rb1 abolished high calcium-induced delayed afterdepolarizations (DADs), depressed the increase in intracellular calcium ([Ca2+]i), relieved calcium overload and protected cardiomyocytes. Rb1 can also reduce the occurrence of ventricular premature beats (VPBs) and ventricular tachycardia (VT) in ischemia-reperfusion (I-R) injury.
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The NACA score as a predictor of ventricular cardiac arrhythmias - A retrospective six-year study. Am J Emerg Med 2019; 38:2249-2253. [PMID: 31924440 DOI: 10.1016/j.ajem.2019.12.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/20/2019] [Accepted: 12/21/2019] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Helicopter Emergency Medical Service (HEMS) conducts the evaluation of a patient's condition using NACA score before transporting the patient to hospital. The conditions inside the rescue helicopter limit or even make it impossible to conduct some medical procedures. An appropriate classification of the patient may lead to a lower possibility of occurrence of adverse events during the flight. The aim of the research was to evaluate the correlation of NACA score with the cardiac arrhythmia that may be life threatening. METHODS A retrospective observational study included a group of 47,131 patients, who were transported by HEMS services between 2012 and 2017. The research was conducted using the analysis of variance ANOVA running a post hoc test. In order to calculate the correlation of variables, Kruskal-Wallis and r-Pearson tests were carried out, interpreting the results according to J. Gilville's scale. The significance level was set at α = 0,05. RESULTS The average number of points using NACA score for the studied group was 4,06 (SD ± 1,38). Twelve heart rhythms were selected while evaluating correlations using NACA score. There was a significant relation between the ECG variable and NACA score (p = 0,003). There was a very strong correlation between NACA score and the following: VF/pVT (r-Pearson = 0,856; p = 0,006), PEA (r-Pearson = 0,810; p = 0,015) and Asystole (r-Pearson = 0,728; p = 0,026). CONCLUSIONS NACA score allows to predict the risk of occurrence of ventricular arrhythmia of the myocardium as well as cardiac arrest. The possibility of occurrence of a life-threatening rhythm is significantly higher in patients classified as NACA IV or higher.
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Liu MB, Vandersickel N, Panfilov AV, Qu Z. R-From-T as a Common Mechanism of Arrhythmia Initiation in Long QT Syndromes. Circ Arrhythm Electrophysiol 2019; 12:e007571. [PMID: 31838916 PMCID: PMC6924944 DOI: 10.1161/circep.119.007571] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/24/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Long QT syndromes (LQTS) arise from many genetic and nongenetic causes with certain characteristic ECG features preceding polymorphic ventricular tachyarrhythmias (PVTs). However, how the many molecular causes result in these characteristic ECG patterns and how these patterns are mechanistically linked to the spontaneous initiation of PVT remain poorly understood. METHODS Anatomic human ventricle and simplified tissue models were used to investigate the mechanisms of spontaneous initiation of PVT in LQTS. RESULTS Spontaneous initiation of PVT was elicited by gradually ramping up ICa,L to simulate the initial phase of a sympathetic surge or by changing the heart rate, reproducing the different genotype-dependent clinical ECG features. In LQTS type 2 (LQT2) and LQTS type 3 (LQT3), T-wave alternans was observed followed by premature ventricular complexes (PVCs). Compensatory pauses occurred resulting in short-long-short sequences. As ICa,L increased further, PVT episodes occurred, always preceded by a short-long-short sequence. However, in LQTS type 1 (LQT1), once a PVC occurred, it always immediately led to an episode of PVT. Arrhythmias in LQT2 and LQT3 were bradycardia dependent, whereas those in LQT1 were not. In all 3 genotypes, PVCs always originated spontaneously from the steep repolarization gradient region and manifested on ECG as R-on-T. We call this mechanism R-from-T, to distinguish it from the classic explanation of R-on-T arrhythmogenesis in which an exogenous PVC coincidentally encounters a repolarizing region. In R-from-T, the PVC and the T wave are causally related, where steep repolarization gradients combined with enhanced ICa,L lead to PVCs emerging from the T wave. Since enhanced ICa,L was required for R-from-T to occur, suppressing window ICa,L effectively prevented arrhythmias in all 3 genotypes. CONCLUSIONS Despite the complex molecular causes, these results suggest that R-from-T is likely a common mechanism for PVT initiation in LQTS. Targeting ICa,L properties, such as suppressing window ICa,L or preventing excessive ICa,L increase, could be an effective unified therapy for arrhythmia prevention in LQTS.
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Affiliation(s)
- Michael B. Liu
- Department of Medicine (M.B.L., Z.Q.), University of California, Los Angeles
| | - Nele Vandersickel
- Department of Physics and Astronomy, Ghent University, Belgium (N.V., A.V.P.)
| | - Alexander V. Panfilov
- Department of Physics and Astronomy, Ghent University, Belgium (N.V., A.V.P.)
- Laboratory of Computational Biology and Medicine, Ural Federal University, Ekaterinburg, Russia (A.V.P.)
| | - Zhilin Qu
- Department of Medicine (M.B.L., Z.Q.), University of California, Los Angeles
- Department of Biomathematics (Z.Q.), University of California, Los Angeles
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42
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Colman MA. Arrhythmia mechanisms and spontaneous calcium release: Bi-directional coupling between re-entrant and focal excitation. PLoS Comput Biol 2019; 15:e1007260. [PMID: 31393876 PMCID: PMC6687119 DOI: 10.1371/journal.pcbi.1007260] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/09/2019] [Indexed: 12/14/2022] Open
Abstract
Spontaneous sub-cellular calcium release events (SCRE) are conjectured to promote rapid arrhythmias associated with conditions such as heart failure and atrial fibrillation: they can underlie the emergence of spontaneous action potentials in single cells which can lead to arrhythmogenic triggers in tissue. The multi-scale mechanisms of the development of SCRE into arrhythmia triggers, and their dynamic interaction with the tissue substrate, remain elusive; rigorous and simultaneous study of dynamics from the nanometre to the centimetre scale is a major challenge. The aim of this study was to develop a computational approach to overcome this challenge and study potential bi-directional coupling between sub-cellular and tissue-scale arrhythmia phenomena. A framework comprising a hierarchy of computational models was developed, which includes detailed single-cell models describing spatio-temporal calcium dynamics in 3D, efficient non-spatial cell models, and both idealised and realistic tissue models. A phenomenological approach was implemented to reproduce SCRE morphology and variability in the efficient cell models, comprising the definition of analytical Spontaneous Release Functions (SRF) whose parameters may be randomly sampled from appropriate distributions in order to match either the 3D cell models or experimental data. Pro-arrhythmogenic pacing protocols were applied to initiate re-entry and promote calcium overload, leading to the emergence of SCRE. The SRF accurately reproduced the dynamics of SCRE and its dependence on environment variables under multiple different conditions. Sustained re-entrant excitation promoted calcium overload, and led to the emergence of focal excitations after termination. A purely functional mechanism of re-entry and focal activity localisation was demonstrated, related to the unexcited spiral wave core. In conclusion, a novel approach has been developed to dynamically model SCRE at the tissue scale, which facilitates novel, detailed multi-scale mechanistic analysis. It was revealed that complex re-entrant excitation patterns and SCRE may be bi-directionally coupled, promoting novel mechanisms of arrhythmia perpetuation.
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Affiliation(s)
- Michael A. Colman
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
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43
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Park SJ, Zhang D, Qi Y, Li Y, Lee KY, Bezzerides VJ, Yang P, Xia S, Kim SL, Liu X, Lu F, Pasqualini FS, Campbell PH, Geva J, Roberts AE, Kleber AG, Abrams DJ, Pu WT, Parker KK. Insights Into the Pathogenesis of Catecholaminergic Polymorphic Ventricular Tachycardia From Engineered Human Heart Tissue. Circulation 2019; 140:390-404. [PMID: 31311300 PMCID: PMC6750809 DOI: 10.1161/circulationaha.119.039711] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Modeling of human arrhythmias with induced pluripotent stem cell-derived cardiomyocytes has focused on single-cell phenotypes. However, arrhythmias are the emergent properties of cells assembled into tissues, and the impact of inherited arrhythmia mutations on tissue-level properties of human heart tissue has not been reported. METHODS Here, we report an optogenetically based, human engineered tissue model of catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmia caused by mutation of the cardiac ryanodine channel and triggered by exercise. We developed a human induced pluripotent stem cell-derived cardiomyocyte-based platform to study the tissue-level properties of engineered human myocardium. We investigated pathogenic mechanisms in CPVT by combining this novel platform with genome editing. RESULTS In our model, CPVT tissues were vulnerable to developing reentrant rhythms when stimulated by rapid pacing and catecholamine, recapitulating hallmark features of the disease. These conditions elevated diastolic Ca2+ levels and increased temporal and spatial dispersion of Ca2+ wave speed, creating a vulnerable arrhythmia substrate. Using Cas9 genome editing, we pinpointed a single catecholamine-driven phosphorylation event, ryanodine receptor-serine 2814 phosphorylation by Ca2+/calmodulin-dependent protein kinase II, that is required to unmask the arrhythmic potential of CPVT tissues. CONCLUSIONS Our study illuminates the molecular and cellular pathogenesis of CPVT and reveals a critical role of calmodulin-dependent protein kinase II-dependent reentry in the tissue-scale mechanism of this disease. We anticipate that this approach will be useful for modeling other inherited and acquired cardiac arrhythmias.
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Affiliation(s)
- Sung-Jin Park
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Donghui Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.).,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Yan Qi
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Yifei Li
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.).,Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu (Y.L.)
| | - Keel Yong Lee
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Vassilios J Bezzerides
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Pengcheng Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Shutao Xia
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, Hubei University, Wuhan, China (D.Z., Y.Q., P.Y., S.X.)
| | - Sean L Kim
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Xujie Liu
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Fujian Lu
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Francesco S Pasqualini
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Patrick H Campbell
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA
| | - Judith Geva
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Amy E Roberts
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Andre G Kleber
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (A.G.K.)
| | - Dominic J Abrams
- Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - William T Pu
- Harvard Stem Cell Institute (W.T.P., K.K.P.), Harvard University, Cambridge, MA.,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.)
| | - Kevin Kit Parker
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (S.-J.P., K.Y.L., S.L.K., F.S.P., P.H.C., K.K.P.), Harvard University, Cambridge, MA.,Harvard Stem Cell Institute (W.T.P., K.K.P.), Harvard University, Cambridge, MA.,Department of Cardiology, Boston Children's Hospital, MA (D.Z., Y.L., V.J.B., X.L., F.L., J.G., A.E.R., D.J.A., W.T.P., K.K.P.).,Sogang-Harvard Research Center for Disease Biophysics, Sogang University, Seoul, South Korea (K.K.P.). Dr Park is currently at the Coulter Department of Biomedical Engineering, Georgia Institute of Technology, and Emory University School of Medicine, Atlanta
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Martin B, Romero G, Salama G. Cardioprotective actions of relaxin. Mol Cell Endocrinol 2019; 487:45-53. [PMID: 30625345 DOI: 10.1016/j.mce.2018.12.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 01/19/2023]
Abstract
Relaxin is a hormone of pregnancy first discovered for its ability to induce ligament relaxation in nonpregnant guinea pig and is important for softening of the birth canal during parturition, decidualization, implantation, nipple development and increased maternal renal perfusion, glomerular filtration, and cardiac output. Subsequently, relaxin has been shown to exert multiple beneficial cardiovascular effects during pathological events such as hypertension, atrial fibrillation, heart failure and myocardial infarction, including suppression of arrhythmia and inflammation, and reversal of fibrosis. Despite extensive studies, the mechanisms underlying relaxin's effects are not well understood. Relaxin signals primarily through its G protein coupled receptor, the relaxin family peptide receptor-1, to activate multiple signaling pathways and this review summarizes our understanding of these pathways as they relate to the cardioprotective actions of relaxin, focusing on relaxin's anti-fibrotic, anti-arrhythmic and anti-inflammatory properties. Further, this review includes a brief overview of relaxin in clinical trials for heart failure and progress in the development of relaxin mimetics.
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Affiliation(s)
- Brian Martin
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Guillermo Romero
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Guy Salama
- Department of Medicine, Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, 15261, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
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45
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Grace A, Willems S, Meyer C, Verma A, Heck P, Zhu M, Shi X, Chou D, Dang L, Scharf C, Scharf G, Beatty G. High-resolution noncontact charge-density mapping of endocardial activation. JCI Insight 2019; 4:126422. [PMID: 30895945 DOI: 10.1172/jci.insight.126422] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/11/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Spatial resolution in cardiac activation maps based on voltage measurement is limited by far-field interference. Precise characterization of electrical sources would resolve this limitation; however, practical charge-based cardiac mapping has not been achieved. METHODS A prototype algorithm, developed from first principles of electrostatic field theory, derives charge density (CD) as a spatial representation of the true sources of the cardiac field. The algorithm processes multiple, simultaneous, noncontact voltage measurements within the cardiac chamber to inversely derive the global distribution of CD sources across the endocardial surface. RESULTS Comparison of CD to an established computer-simulated model of atrial conduction demonstrated feasibility in terms of spatial, temporal, and morphologic metrics. Inverse reconstruction matched simulation with median spatial errors of 1.73 mm and 2.41 mm for CD and voltage, respectively. Median temporal error was less than 0.96 ms and morphologic correlation was greater than 0.90 for both CD and voltage. Activation patterns observed in human atrial flutter reproduced those established through contact maps, with a 4-fold improvement in resolution noted for CD over voltage. Global activation maps (charge density-based) are reported in atrial fibrillation with confirmed reduction of far-field interference. Arrhythmia cycle-length slowing and termination achieved through ablation of critical points demonstrated in the maps indicates both mechanistic and pathophysiological relevance. CONCLUSION Global maps of cardiac activation based on CD enable classification of conduction patterns and localized nonpulmonary vein therapeutic targets in atrial fibrillation. The measurement capabilities of the approach have roles spanning deep phenotyping to therapeutic application. TRIAL REGISTRATION ClinicalTrials.gov NCT01875614. FUNDING The National Institute for Health Research (NIHR) Translational Research Program at Royal Papworth Hospital and Acutus Medical.
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Affiliation(s)
- Andrew Grace
- Royal Papworth Hospital Foundation Trust, Cambridge University Health Partners, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Stephan Willems
- University Heart Center, University Hospital, Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Meyer
- University Heart Center, University Hospital, Hamburg-Eppendorf, Hamburg, Germany
| | - Atul Verma
- Southlake Regional Health Center, Newmarket, University of Toronto, Ontario, Canada
| | - Patrick Heck
- Royal Papworth Hospital Foundation Trust, Cambridge University Health Partners, Cambridge, United Kingdom
| | - Min Zhu
- Acutus Medical Inc., Carlsbad, California, USA
| | - Xinwei Shi
- Acutus Medical Inc., Carlsbad, California, USA
| | | | - Lam Dang
- Cardiovascular Center, Klinik im Park, Zürich, Switzerland
| | | | - Günter Scharf
- Physics Institute, University of Zurich, Zurich, Switzerland
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Callaghan NI, Hadipour-Lakmehsari S, Lee SH, Gramolini AO, Simmons CA. Modeling cardiac complexity: Advancements in myocardial models and analytical techniques for physiological investigation and therapeutic development in vitro. APL Bioeng 2019; 3:011501. [PMID: 31069331 PMCID: PMC6481739 DOI: 10.1063/1.5055873] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 12/31/2018] [Indexed: 02/06/2023] Open
Abstract
Cardiomyopathies, heart failure, and arrhythmias or conduction blockages impact millions of patients worldwide and are associated with marked increases in sudden cardiac death, decline in the quality of life, and the induction of secondary pathologies. These pathologies stem from dysfunction in the contractile or conductive properties of the cardiomyocyte, which as a result is a focus of fundamental investigation, drug discovery and therapeutic development, and tissue engineering. All of these foci require in vitro myocardial models and experimental techniques to probe the physiological functions of the cardiomyocyte. In this review, we provide a detailed exploration of different cell models, disease modeling strategies, and tissue constructs used from basic to translational research. Furthermore, we highlight recent advancements in imaging, electrophysiology, metabolic measurements, and mechanical and contractile characterization modalities that are advancing our understanding of cardiomyocyte physiology. With this review, we aim to both provide a biological framework for engineers contributing to the field and demonstrate the technical basis and limitations underlying physiological measurement modalities for biologists attempting to take advantage of these state-of-the-art techniques.
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Affiliation(s)
| | | | | | | | - Craig A. Simmons
- Author to whom correspondence should be addressed: . Present address: Ted Rogers Centre for Heart
Research, 661 University Avenue, 14th Floor Toronto, Ontario M5G 1M1, Canada. Tel.:
416-946-0548. Fax: 416-978-7753
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47
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Jiang X, Kong B, Shuai W, Shen C, Yang F, Fu H, Huang H. Loss of MD1 exacerbates myocardial ischemia/reperfusion injury and susceptibility to ventricular arrhythmia. Eur J Pharmacol 2019; 844:79-86. [DOI: 10.1016/j.ejphar.2018.11.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 11/13/2018] [Accepted: 11/16/2018] [Indexed: 12/23/2022]
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48
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Dalia AA, Essandoh M, Cronin B, Hussain N, Gerstein NS, Schulman P. A Narrative Review for Anesthesiologists of the 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death. J Cardiothorac Vasc Anesth 2019; 33:1722-1730. [PMID: 30685157 DOI: 10.1053/j.jvca.2019.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Indexed: 11/11/2022]
Abstract
This is a review of the 2017 AHA/ACC/HRS Guidelines with guidance for intraoperative physicians. Ventricular arrhythmias occurring during the perioperative period have the potential for significant morbidity and mortality. Hence, an in-depth knowledge of VA mechanisms, prevention, and management is crucial for all clinicians caring for these at-risk patients in the perioperative period. Perioperative optimization of patients with a known or suspected VA should be tailored to the specific patient population and condition as outlined in this manuscript.
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Affiliation(s)
- Adam A Dalia
- Department of Anesthesiology, Pain Medicine, and Critical Care Medicine, The Massachusetts General Hospital, Harvard Medical School, Boston, MA.
| | - Michael Essandoh
- Department of Anesthesiology, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Brett Cronin
- Department of Anesthesiology, University of California, San Diego, CA
| | - Nasir Hussain
- Department of Anesthesiology, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Neal S Gerstein
- Department of Anesthesiology and Critical Care Medicine, School of Medicine, University of New Mexico, Albuquerque, NM
| | - Peter Schulman
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR
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49
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Huang X, Song Z, Qu Z. Determinants of early afterdepolarization properties in ventricular myocyte models. PLoS Comput Biol 2018; 14:e1006382. [PMID: 30475801 PMCID: PMC6283611 DOI: 10.1371/journal.pcbi.1006382] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/06/2018] [Accepted: 09/17/2018] [Indexed: 12/20/2022] Open
Abstract
Early afterdepolarizations (EADs) are spontaneous depolarizations during the repolarization phase of an action potential in cardiac myocytes. It is widely known that EADs are promoted by increasing inward currents and/or decreasing outward currents, a condition called reduced repolarization reserve. Recent studies based on bifurcation theories show that EADs are caused by a dual Hopf-homoclinic bifurcation, bringing in further mechanistic insights into the genesis and dynamics of EADs. In this study, we investigated the EAD properties, such as the EAD amplitude, the inter-EAD interval, and the latency of the first EAD, and their major determinants. We first made predictions based on the bifurcation theory and then validated them in physiologically more detailed action potential models. These properties were investigated by varying one parameter at a time or using parameter sets randomly drawn from assigned intervals. The theoretical and simulation results were compared with experimental data from the literature. Our major findings are that the EAD amplitude and takeoff potential exhibit a negative linear correlation; the inter-EAD interval is insensitive to the maximum ionic current conductance but mainly determined by the kinetics of ICa,L and the dual Hopf-homoclinic bifurcation; and both inter-EAD interval and latency vary largely from model to model. Most of the model results generally agree with experimental observations in isolated ventricular myocytes. However, a major discrepancy between modeling results and experimental observations is that the inter-EAD intervals observed in experiments are mainly between 200 and 500 ms, irrespective of species, while those of the mathematical models exhibit a much wider range with some models exhibiting inter-EAD intervals less than 100 ms. Our simulations show that the cause of this discrepancy is likely due to the difference in ICa,L recovery properties in different mathematical models, which needs to be addressed in future action potential model development. Early afterdepolarizations (EADs) are abnormal depolarizations during the plateau phase of action potential in cardiac myocytes, arising from a dual Hopf-homoclinic bifurcation. The same bifurcations are also responsible for certain types of bursting behaviors in other cell types, such as beta cells and neuronal cells. EADs are known to play important role in the genesis of lethal arrhythmias and have been widely studied in both experiments and computer models. However, a detailed comparison between the properties of EADs observed in experiments and those from mathematical models have not been carried out. In this study, we performed theoretical analyses and computer simulations of different ventricular action potential models as well as different species to investigate the properties of EADs and compared these properties to those observed in experiments. While the EAD properties in the action potential models capture many of the EAD properties seen in experiments, the inter-EAD intervals in the computer models differ a lot from model to model, and some of them show very large discrepancy with those observed in experiments. This discrepancy needs to be addressed in future cardiac action potential model development.
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Affiliation(s)
- Xiaodong Huang
- Department of Physics, South China University of Technology, Guangzhou, China
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Department of Biomathematics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail:
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50
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Landaw J, Qu Z. Control of voltage-driven instabilities in cardiac myocytes with memory. CHAOS (WOODBURY, N.Y.) 2018; 28:113122. [PMID: 30501225 PMCID: PMC6274634 DOI: 10.1063/1.5040854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/29/2018] [Indexed: 06/09/2023]
Abstract
Sudden cardiac death is known to be associated with dynamical instabilities in the heart, and thus control of dynamical instabilities is considered a potential therapeutic strategy. Different control methods were developed previously, including time-delayed feedback pacing control and constant diastolic interval pacing control. Experimental, theoretical, and simulation studies have examined the efficacy of these control methods in stabilizing action potential dynamics. In this study, we apply these control methods to control complex action potential (AP) dynamics under two diseased conditions: early repolarization syndrome and long QT syndrome, in which voltage-driven instabilities occur in the presence of short-term cardiac memory. In addition, we also develop a feedback pacing method to stabilize these instabilities. We perform theoretical analyses using iterated map models and carry out numerical simulations of AP models. We show that under the normal condition where the memory effect is minimal, all three methods can effectively control the action potential duration (APD) dynamics. Under the two diseased conditions where the memory effect is exacerbated, constant diastolic pacing control is least effective, while the feedback pacing control is most effective. Under a very strong memory effect, all three methods fail to stabilize the voltage-driven instabilities. The failure of effective control is due to memory and the all-or-none AP dynamics which results in very steep changes in APD.
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Affiliation(s)
- Julian Landaw
- Department of Medicine (Cardiology), University of California, Los Angeles, California 90095, USA
| | - Zhilin Qu
- Department of Medicine (Cardiology), University of California, Los Angeles, California 90095, USA
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