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Li P, Zhang J, Hayashi H, Yue J, Li W, Yang C, Sun C, Shi J, Huberman-Shlaes J, Hibino N, Tian B. Monolithic silicon for high spatiotemporal translational photostimulation. Nature 2024; 626:990-998. [PMID: 38383782 DOI: 10.1038/s41586-024-07016-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 01/02/2024] [Indexed: 02/23/2024]
Abstract
Electrode-based electrical stimulation underpins several clinical bioelectronic devices, including deep-brain stimulators1,2 and cardiac pacemakers3. However, leadless multisite stimulation is constrained by the technical difficulties and spatial-access limitations of electrode arrays. Optogenetics offers optically controlled random access with high spatiotemporal capabilities, but clinical translation poses challenges4-6. Here we show tunable spatiotemporal photostimulation of cardiac systems using a non-genetic platform based on semiconductor-enabled biomodulation interfaces. Through spatiotemporal profiling of photoelectrochemical currents, we assess the magnitude, precision, accuracy and resolution of photostimulation in four leadless silicon-based monolithic photoelectrochemical devices. We demonstrate the optoelectronic capabilities of the devices through optical overdrive pacing of cultured cardiomyocytes (CMs) targeting several regions and spatial extents, isolated rat hearts in a Langendorff apparatus, in vivo rat hearts in an ischaemia model and an in vivo mouse heart model with transthoracic optical pacing. We also perform the first, to our knowledge, optical override pacing and multisite pacing of a pig heart in vivo. Our systems are readily adaptable for minimally invasive clinical procedures using our custom endoscopic delivery device, with which we demonstrate closed-thoracic operations and endoscopic optical stimulation. Our results indicate the clinical potential of the leadless, lightweight and multisite photostimulation platform as a pacemaker in cardiac resynchronization therapy (CRT), in which lead-placement complications are common.
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Affiliation(s)
- Pengju Li
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, USA
| | - Jing Zhang
- The James Franck Institute, The University of Chicago, Chicago, IL, USA
| | - Hidenori Hayashi
- Section of Cardiac Surgery, Department of Surgery, The University of Chicago, Chicago, IL, USA
| | - Jiping Yue
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Wen Li
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | - Chuanwang Yang
- The James Franck Institute, The University of Chicago, Chicago, IL, USA
| | - Changxu Sun
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, USA
| | - Jiuyun Shi
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
| | | | - Narutoshi Hibino
- Section of Cardiac Surgery, Department of Surgery, The University of Chicago, Chicago, IL, USA.
| | - Bozhi Tian
- The James Franck Institute, The University of Chicago, Chicago, IL, USA.
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
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2
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Dhakal BP, Patel NA, Garg L, Frankel DS, Hyman MC, Guandalini GS, Supple GE, Nazarian S, Kumareswaran R, Riley MP, Santangeli P, Lin D, Callans DJ, Arkles J, Schaller RD, Tschabrunn CM, Zado ES, Marchlinski FE, Dixit S. Utility of Very High-Output Pacing to Identify VT Circuits in Patients Manifesting Traditionally Inexcitable Scar. JACC Clin Electrophysiol 2023; 9:2523-2533. [PMID: 37715743 DOI: 10.1016/j.jacep.2023.08.015] [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: 06/13/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 09/18/2023]
Abstract
BACKGROUND Entrainment and pace mapping are used to identify critical components (CCs) of ventricular tachycardia (VT) circuits. In patients with dense myocardial scarring, VT circuits may elude capture at standard high pacing outputs (up to 10 mA at a 2-millisecond pulse width). OBJECTIVES The purpose of this study was to assess the utility of very high-output pacing (V-HOP, 50 mA at 2 milliseconds) for identifying CCs of VT circuits after standard high pacing output failed to elicit capture in densely scarred myocardial tissue. METHODS Our standard VT ablation approach included electroanatomic mapping for substrate characterization and entrainment and/or pace mapping to identify CCs of VT circuits. Patients that required V-HOP to capture sites of interest comprised the study cohort. Ablation endpoints were VT termination and noninducibility. RESULTS Twenty-five patients (71 ± 10 years of age, all males) undergoing 26 VT ablations met the inclusion criteria. The mean left ventricular ejection fraction was 30% ± 14%, and 85% had ischemic cardiomyopathy. V-HOP was used to successfully entrain VT in 17 patients, yielding central isthmus sites in 10 and entrance/exit sites in 4. VT terminated with radiofrequency ablation at these sites in 15 patients. In 9 patients, V-HOP identified scar locations with a delayed exit. Acute procedural success was achieved in 24 patients without any adverse events. Over a follow-up period of 16 ± 21 months, 2 patients experienced VT recurrence requiring repeat ablation during which the same location was targeted successfully in 1 patient. CONCLUSIONS In VT patients with a dense scar that is traditionally inexcitable, V-HOP can identify CCs of the re-entrant circuit and guide successful ablation.
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Affiliation(s)
- Bishnu P Dhakal
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Neel A Patel
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Lohit Garg
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David S Frankel
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Matthew C Hyman
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Gustavo S Guandalini
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Gregory E Supple
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Saman Nazarian
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ramanan Kumareswaran
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael P Riley
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Pasquale Santangeli
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David Lin
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David J Callans
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jeffrey Arkles
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert D Schaller
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Cory M Tschabrunn
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Erica S Zado
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Francis E Marchlinski
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sanjay Dixit
- Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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3
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Abuelnasr B, Stinchcombe AR. A multi-scale simulation of retinal physiology. Math Biosci 2023; 363:109053. [PMID: 37517550 DOI: 10.1016/j.mbs.2023.109053] [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: 03/31/2023] [Revised: 06/27/2023] [Accepted: 07/21/2023] [Indexed: 08/01/2023]
Abstract
We present a detailed physiological model of the (human) retina that includes the biochemistry and electrophysiology of phototransduction, neuronal electrical coupling, and the spherical geometry of the eye. The model is a parabolic-elliptic system of partial differential equations based on the mathematical framework of the bi-domain equations, which we have generalized to account for multiple cell-types. We discretize in space with non-uniform finite differences and step through time with a custom adaptive time-stepper that employs a backward differentiation formula and an inexact Newton method. A refinement study confirms the accuracy and efficiency of our numerical method. Numerical simulations using the model compare favorably with experimental findings, such as desensitization to light stimuli and calcium buffering in photoreceptors. Other numerical simulations suggest an interplay between photoreceptor gap junctions and inner segment, but not outer segment, calcium concentration. Applications of this model and simulation include analysis of retinal calcium imaging experiments, the design of electroretinograms, the design of visual prosthetics, and studies of ephaptic coupling within the retina.
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Affiliation(s)
- Belal Abuelnasr
- Department of Mathematics, University of Toronto, Toronto, ON, M5S 2E4, Canada.
| | - Adam R Stinchcombe
- Department of Mathematics, University of Toronto, Toronto, ON, M5S 2E4, Canada.
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4
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Zhang H, Patton HN, Nagahawatte ND, Athavale ON, Walcott GP, Cheng LK, Rogers JM. Optical Mapping of Virtual Electrode Polarization Pattern and Its Relationship with Pacemaker Location during Gastric Pacing . ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082999 DOI: 10.1109/embc40787.2023.10340002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Gastric rhythmic contractions are regulated by bioelectrical events known as slow waves (SW). Abnormal SW activity is associated with gastric motility disorders. Gastric pacing is a potential treatment method to restore rhythmic SW activity. However, to date, the efficacy of gastric pacing is inconsistent and the underlying mechanisms of gastric pacing are poorly understood. Optical mapping is widely used in cardiac electrophysiology studies. Its immunity to pacing artifacts offers a distinct advantage over conventional electrical mapping for studying pacing. In the present study, we first found that optical mapping can image pacing-induced virtual electrode polarization patterns in the stomach (adjacent regions of depolarized and hyperpolarized tissue). Second, we found that elicited SWs usually (15 of 16) originated from the depolarized areas of the stimulated region (virtual cathodes). To our knowledge, this is the first direct observation of virtual electrode polarization patterns in the stomach. Conclusions: Optical mapping can image virtual electrode polarization patterns during gastric pacing with high spatial resolution.Clinical Relevance- Gastric pacing is a potential therapeutic method for gastric motility disorders. This study provides direct observation of virtual electrode polarization pattern during gastric pacing and improves our understanding of the mechanisms underlying gastric pacing..
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Bowman AJ, Huang C, Schnitzer MJ, Kasevich MA. Wide-field fluorescence lifetime imaging of neuron spiking and subthreshold activity in vivo. Science 2023; 380:1270-1275. [PMID: 37347862 PMCID: PMC10361454 DOI: 10.1126/science.adf9725] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 05/16/2023] [Indexed: 06/24/2023]
Abstract
The development of voltage-sensitive fluorescent probes suggests fluorescence lifetime as a promising readout for electrical activity in biological systems. Existing approaches fail to achieve the speed and sensitivity required for voltage imaging in neuroscience applications. We demonstrated that wide-field electro-optic fluorescence lifetime imaging microscopy (EO-FLIM) allows lifetime imaging at kilohertz frame-acquisition rates, spatially resolving action potential propagation and subthreshold neural activity in live adult Drosophila. Lifetime resolutions of <5 picoseconds at 1 kilohertz were achieved for single-cell voltage recordings. Lifetime readout is limited by photon shot noise, and the method provides strong rejection of motion artifacts and technical noise sources. Recordings revealed local transmembrane depolarizations, two types of spikes with distinct fluorescence lifetimes, and phase locking of spikes to an external mechanical stimulus.
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Affiliation(s)
- Adam J Bowman
- Physics Department, Stanford University, Stanford, CA 94305, USA
| | - Cheng Huang
- James H. Clark Center, Stanford University, Stanford, CA 94305, USA
| | - Mark J Schnitzer
- James H. Clark Center, Stanford University, Stanford, CA 94305, USA
- CNC Program, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Mark A Kasevich
- Physics Department, Stanford University, Stanford, CA 94305, USA
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6
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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7
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Abstract
The global burden caused by cardiovascular disease is substantial, with heart disease representing the most common cause of death around the world. There remains a need to develop better mechanistic models of cardiac function in order to combat this health concern. Heart rhythm disorders, or arrhythmias, are one particular type of disease which has been amenable to quantitative investigation. Here we review the application of quantitative methodologies to explore dynamical questions pertaining to arrhythmias. We begin by describing single-cell models of cardiac myocytes, from which two and three dimensional models can be constructed. Special focus is placed on results relating to pattern formation across these spatially-distributed systems, especially the formation of spiral waves of activation. Next, we discuss mechanisms which can lead to the initiation of arrhythmias, focusing on the dynamical state of spatially discordant alternans, and outline proposed mechanisms perpetuating arrhythmias such as fibrillation. We then review experimental and clinical results related to the spatio-temporal mapping of heart rhythm disorders. Finally, we describe treatment options for heart rhythm disorders and demonstrate how statistical physics tools can provide insights into the dynamics of heart rhythm disorders.
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Affiliation(s)
- Wouter-Jan Rappel
- Department of Physics, University of California San Diego, La Jolla, CA 92037
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8
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Wang B, Shah M, Williams LN, de Jongh Curry AL, Hong Y, Zhang G, Liao J. Acellular Myocardial Scaffolds and Slices Fabrication, and Method for Applying Mechanical and Electrical Simulation to Tissue Construct. Methods Mol Biol 2022; 2485:55-70. [PMID: 35618898 PMCID: PMC9811994 DOI: 10.1007/978-1-0716-2261-2_4] [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] [Indexed: 01/07/2023]
Abstract
Cardiac tissue engineering/regeneration using decellularized myocardium has attracted great research attention due to its potential benefit to myocardial infarction (MI) treatment. Here, we described an optimal decellularization protocol to generate 3D porcine myocardial scaffolds with well-preserved cardiomyocyte lacunae, myocardial slices as a biomimetic cell culture and delivery platform, and a multi-stimulation bioreactor that is able to provide coordinated mechanical and electrical stimulations for facilitating cardiac construct development.
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Affiliation(s)
- Bo Wang
- Joint Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin, Milwaukee, WI, USA
| | - Mickey Shah
- Department of Biomedical Engineering, The University of Akron, Akron, OH, USA
| | - Lakiesha N Williams
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | | | - Yi Hong
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA
| | - Ge Zhang
- Department of Biomedical Engineering, The University of Akron, Akron, OH, USA.
| | - Jun Liao
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA.
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9
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Roth BJ. Bidomain modeling of electrical and mechanical properties of cardiac tissue. BIOPHYSICS REVIEWS 2021; 2:041301. [PMID: 38504719 PMCID: PMC10903405 DOI: 10.1063/5.0059358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/15/2021] [Indexed: 03/21/2024]
Abstract
Throughout the history of cardiac research, there has been a clear need to establish mathematical models to complement experimental studies. In an effort to create a more complete picture of cardiac phenomena, the bidomain model was established in the late 1970s to better understand pacing and defibrillation in the heart. This mathematical model has seen ongoing use in cardiac research, offering mechanistic insight that could not be obtained from experimental pursuits. Introduced from a historical perspective, the origins of the bidomain model are reviewed to provide a foundation for researchers new to the field and those conducting interdisciplinary research. The interplay of theory and experiment with the bidomain model is explored, and the contributions of this model to cardiac biophysics are critically evaluated. Also discussed is the mechanical bidomain model, which is employed to describe mechanotransduction. Current challenges and outstanding questions in the use of the bidomain model are addressed to give a forward-facing perspective of the model in future studies.
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Affiliation(s)
- Bradley J. Roth
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
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10
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Post AD, Buchan S, John M, Safavi-Naeini P, Cosgriff-Hernández E, Razavi M. Reconstituting electrical conduction in soft tissue: the path to replace the ablationist. Europace 2021; 23:1892-1902. [PMID: 34477862 DOI: 10.1093/europace/euab187] [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: 03/23/2021] [Accepted: 07/08/2021] [Indexed: 11/13/2022] Open
Abstract
Cardiac arrhythmias are a leading cause of morbidity and mortality in the developed world. A common mechanism underlying many of these arrhythmias is re-entry, which may occur when native conduction pathways are disrupted, often by myocardial infarction. Presently, re-entrant arrhythmias are most commonly treated with antiarrhythmic drugs and myocardial ablation, although both treatment methods are associated with adverse side effects and limited efficacy. In recent years, significant advancements in the field of biomaterials science have spurred increased interest in the development of novel therapies that enable restoration of native conduction in damaged or diseased myocardium. In this review, we assess the current landscape of materials-based approaches to eliminating re-entrant arrhythmias. These approaches potentially pave the way for the eventual replacement of myocardial ablation as a preferred therapy for such pathologies.
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Affiliation(s)
- Allison D Post
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX 77030, USA
| | - Skylar Buchan
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX 77030, USA
| | - Mathews John
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX 77030, USA
| | - Payam Safavi-Naeini
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX 77030, USA
| | | | - Mehdi Razavi
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX 77030, USA.,Department of Cardiology, Baylor College of Medicine, Houston, TX, USA
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11
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Dell'Era G, Gravellone M, Scacchi S, Franzone PC, Pavarino LF, Boggio E, Prenna E, De Vecchi F, Occhetta E, Devecchi C, Patti G. A clinical-in silico study on the effectiveness of multipoint bicathodic and cathodic-anodal pacing in cardiac resynchronization therapy. Comput Biol Med 2021; 136:104661. [PMID: 34332350 DOI: 10.1016/j.compbiomed.2021.104661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 11/18/2022]
Abstract
Up to one-third of patients undergoing cardiac resynchronization therapy (CRT) are nonresponders. Multipoint bicathodic and cathodic-anodal left ventricle (LV) stimulations could overcome this clinical challenge, but their effectiveness remains controversial. Here we evaluate the performance of such stimulations through both in vivo and in silico experiments, the latter based on computer electromechanical modeling. Seven patients, all candidates for CRT, received a quadripolar LV lead. Four stimulations were tested: right ventricular (RVS); conventional single point biventricular (S-BS); multipoint biventricular bicathodic (CC-BS) and multipoint biventricular cathodic-anodal (CA-BS). The following parameters were processed: QRS duration; maximal time derivative of arterial pressure (dPdtmax); systolic arterial pressure (Psys); and stroke volume (SV). Echocardiographic data of each patient were then obtained to create an LV geometric model. Numerical simulations were based on a strongly coupled Bidomain electromechanical coupling model. Considering the in vivo parameters, when comparing S-BS to RVS, there was no significant decrease in SV (from 45 ± 11 to 44 ± 20 ml) and 6% and 4% increases of dPdtmax and Psys, respectively. Focusing on in silico parameters, with respect to RVS, S-BS exhibited a significant increase of SV, dPdtmax and Psys. Neither the in vivo nor in silico results showed any significant hemodynamic and electrical difference among S-BS, CC-BS and CA-BS configurations. These results show that CC-BS and CA-BS yield a comparable CRT performance, but they do not always yield improvement in terms of hemodynamic parameters with respect to S-BS. The computational results confirmed the in vivo observations, thus providing theoretical support to the clinical experiments.
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Affiliation(s)
- G Dell'Era
- Cardiologia 1, Azienda Ospedaliera Universitaria "Maggiore Della Carità", Novara, Italy
| | - M Gravellone
- Divisione di Cardiologia, Ospedale Degli Infermi, Biella, Italy
| | - S Scacchi
- Dipartimento di Matematica, Università Degli Studi di Milano, Via Saldini 50, 20133, Milano, Italy.
| | - P Colli Franzone
- Dipartimento di Matematica, Università Degli Studi di Pavia, Via Ferrata 1, 27100, Pavia, Italy
| | - L F Pavarino
- Dipartimento di Matematica, Università Degli Studi di Pavia, Via Ferrata 1, 27100, Pavia, Italy
| | - E Boggio
- Divisione di Cardiologia, Ospedale Degli Infermi, Biella, Italy
| | - E Prenna
- Cardiologia 1, Azienda Ospedaliera Universitaria "Maggiore Della Carità", Novara, Italy
| | - F De Vecchi
- Divisione di Cardiologia, Ospedale Sant'Andrea, Vercelli, Italy
| | - E Occhetta
- Divisione di Cardiologia, Ospedale Sant'Andrea, Vercelli, Italy
| | - C Devecchi
- Divisione di Cardiologia, Ospedale Sant'Andrea, Vercelli, Italy
| | - G Patti
- Cardiologia 1, Azienda Ospedaliera Universitaria "Maggiore Della Carità", Novara, Italy; Dipartimento di Medicina Traslazionale, Università Del Piemonte Orientale, Novara, Italy
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12
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Boscamp NS, Liberman L, Silver ES. Anodal stimulation in pediatric patients with permanent epicardial ventricular pacemakers. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2021; 44:1593-1598. [PMID: 34287953 DOI: 10.1111/pace.14323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/08/2021] [Accepted: 07/18/2021] [Indexed: 11/27/2022]
Abstract
OBJECTIVES We aimed to measure the frequency and factors associated with anodal stimulation in a pediatric population with epicardial pacing leads. BACKGROUND In bipolar pacemakers, capture of the myocardium typically occurs at the cathode. However, AS with capture at the anode has been described. This has not been described in epicardial pacemakers. METHODS Retrospective data were collected from patients ≤ 21 years of age with permanent bipolar epicardial ventricular pacemakers from 1/2017 to 1/2018. AS was defined as a clear change on surface ECG in at least one of the 12 leads assessed by two blinded pediatric electrophysiologists. RESULTS Twenty-four bipolar leads in 23 patients were included in the study. One patient had both biventricular leads tested. Median age was 7.1 years (IQR 5.0-10.9), weight was 20.9 kg (IQR 16.5-33.5), and 65% were male. Testing was performed at a median of 2.8 years (IQR 1.6-6.1) after implant. Congenital heart disease was present in 57%. Complete heart block was the pacemaker indication in 78%. AS was identified in 16/24 (67%) of leads tested. Identification of AS was associated with presence of congenital heart disease (p = 0.004) and 3DD between electrodes (p = 0.04). CONCLUSIONS AS is common in pediatric patients and was associated with a history of congenital heart disease and greater estimated 3DD between electrodes. The prevalent nature of AS may allow clinicians to utilize existing pacemakers as multisite pacing systems.
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Affiliation(s)
- Nicholas S Boscamp
- Division of Pediatric Cardiology, Morgan Stanley Children's Hospital of New York, Columbia University Irving Medical Center, New York, New York, USA
| | - Leonardo Liberman
- Division of Pediatric Cardiology, Morgan Stanley Children's Hospital of New York, Columbia University Irving Medical Center, New York, New York, USA
| | - Eric S Silver
- Division of Pediatric Cardiology, Morgan Stanley Children's Hospital of New York, Columbia University Irving Medical Center, New York, New York, USA
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13
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Cusimano N, Gerardo-Giorda L, Gizzi A. A space-fractional bidomain framework for cardiac electrophysiology: 1D alternans dynamics. CHAOS (WOODBURY, N.Y.) 2021; 31:073123. [PMID: 34340362 DOI: 10.1063/5.0050897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Cardiac electrophysiology modeling deals with a complex network of excitable cells forming an intricate syncytium: the heart. The electrical activity of the heart shows recurrent spatial patterns of activation, known as cardiac alternans, featuring multiscale emerging behavior. On these grounds, we propose a novel mathematical formulation for cardiac electrophysiology modeling and simulation incorporating spatially non-local couplings within a physiological reaction-diffusion scenario. In particular, we formulate, a space-fractional electrophysiological framework, extending and generalizing similar works conducted for the monodomain model. We characterize one-dimensional excitation patterns by performing an extended numerical analysis encompassing a broad spectrum of space-fractional derivative powers and various intra- and extracellular conductivity combinations. Our numerical study demonstrates that (i) symmetric properties occur in the conductivity parameters' space following the proposed theoretical framework, (ii) the degree of non-local coupling affects the onset and evolution of discordant alternans dynamics, and (iii) the theoretical framework fully recovers classical formulations and is amenable for parametric tuning relying on experimental conduction velocity and action potential morphology.
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Affiliation(s)
| | | | - Alessio Gizzi
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
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14
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Clementy N, Bodin A, Bisson A, Teixeira-Gomes AP, Roger S, Angoulvant D, Labas V, Babuty D. The Defibrillation Conundrum: New Insights into the Mechanisms of Shock-Related Myocardial Injury Sustained from a Life-Saving Therapy. Int J Mol Sci 2021; 22:5003. [PMID: 34066832 PMCID: PMC8125879 DOI: 10.3390/ijms22095003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 11/16/2022] Open
Abstract
Implantable cardiac defibrillators (ICDs) are recommended to prevent the risk of sudden cardiac death. However, shocks are associated with an increased mortality with a dose response effect, and a strategy of reducing electrical therapy burden improves the prognosis of implanted patients. We review the mechanisms of defibrillation and its consequences, including cell damage, metabolic remodeling, calcium metabolism anomalies, and inflammatory and pro-fibrotic remodeling. Electrical shocks do save lives, but also promote myocardial stunning, heart failure, and pro-arrhythmic effects as seen in electrical storms. Limiting unnecessary implantations and therapies and proposing new methods of defibrillation in the future are recommended.
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Affiliation(s)
- Nicolas Clementy
- Service de Cardiologie, Hôpital Trousseau, Université de Tours, 37044 Tours, France; (A.B.); (A.B.); (D.A.); (D.B.)
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France;
| | - Alexandre Bodin
- Service de Cardiologie, Hôpital Trousseau, Université de Tours, 37044 Tours, France; (A.B.); (A.B.); (D.A.); (D.B.)
| | - Arnaud Bisson
- Service de Cardiologie, Hôpital Trousseau, Université de Tours, 37044 Tours, France; (A.B.); (A.B.); (D.A.); (D.B.)
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France;
| | - Ana-Paula Teixeira-Gomes
- Plate-forme de Chirurgie et d’Imagerie pour la Recherche et l’Enseignement (CIRE), INRA, Université de Tours, CHU de Tours, 37380 Nouzilly, France; (A.-P.T.-G.); (V.L.)
| | - Sebastien Roger
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France;
| | - Denis Angoulvant
- Service de Cardiologie, Hôpital Trousseau, Université de Tours, 37044 Tours, France; (A.B.); (A.B.); (D.A.); (D.B.)
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France;
| | - Valérie Labas
- Plate-forme de Chirurgie et d’Imagerie pour la Recherche et l’Enseignement (CIRE), INRA, Université de Tours, CHU de Tours, 37380 Nouzilly, France; (A.-P.T.-G.); (V.L.)
| | - Dominique Babuty
- Service de Cardiologie, Hôpital Trousseau, Université de Tours, 37044 Tours, France; (A.B.); (A.B.); (D.A.); (D.B.)
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France;
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15
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Tomii N, Yamazaki M, Ashihara T, Nakazawa K, Shibata N, Honjo H, Sakuma I. Spatial phase discontinuity at the center of moving cardiac spiral waves. Comput Biol Med 2021; 130:104217. [PMID: 33516959 DOI: 10.1016/j.compbiomed.2021.104217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 01/10/2021] [Accepted: 01/10/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Precise analysis of cardiac spiral wave (SW) dynamics is essential for effective arrhythmia treatment. Although the phase singularity (PS) point in the spatial phase map has been used to determine the cardiac SW center for decades, quantitative detection algorithms that assume PS as a point fail to trace complex and rapid PS dynamics. Through a detailed analysis of numerical simulations, we examined our hypothesis that a boundary of spatial phase discontinuity induced by a focal conduction block exists around the moving SW center in the phase map. METHOD In a numerical simulation model of a 2D cardiac sheet, three different types of SWs (short wavelength; long wavelength; and low excitability) were induced by regulating ion channels. Discontinuities of all boundaries among adjacent cells at each instance were evaluated by calculating the phase bipolarity (PB). The total amount of phase transition (PTA) in each cell during the study period was evaluated. RESULTS Pivoting, drifting, and shifting SWs were observed in the short-wavelength, low-excitability, and long-wavelength models, respectively. For both the drifting and shifting cases, long high-PB edges were observed on the SW trajectories. In all cases, the conduction block (CB) was observed at the same boundaries. These were also identical to the boundaries in the PTA maps. CONCLUSIONS The analysis of the simulations revealed that the conduction block at the center of a moving SW induces discontinuous boundaries in spatial phase maps that represent a more appropriate model of the SW center than the PS point.
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Affiliation(s)
- Naoki Tomii
- Faculty of Medicine, The University of Tokyo, 7 -3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
| | - Masatoshi Yamazaki
- School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takashi Ashihara
- Shiga University of Medical Science, Setatsukinowa-cho, Otsu-city, Shiga, 520-2192, Japan
| | - Kazuo Nakazawa
- Morinomiya University of Medical Sciences, 1-26-16 Minami-Kohoku, Suminoe-ku, Osaka City, 559-8611, Japan
| | - Nitaro Shibata
- Shinjuku Mitsui Building Clinic, 2-1-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo, 163-0404, Japan
| | - Haruo Honjo
- Research Institute of Environmental Medicine, Nagoya University, Furo-cho Chikusa-ku, Nagoya City, Aichi, 464-8601, Japan
| | - Ichiro Sakuma
- School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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16
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Wang H, Wang J, Cai G, Liu Y, Qu Y, Wu T. A Physical Perspective to the Inductive Function of Myelin-A Missing Piece of Neuroscience. Front Neural Circuits 2021; 14:562005. [PMID: 33536878 PMCID: PMC7848263 DOI: 10.3389/fncir.2020.562005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 12/09/2020] [Indexed: 11/21/2022] Open
Abstract
Starting from the inductance in neurons, two physical origins are discussed, which are the coil inductance of myelin and the piezoelectric effect of the cell membrane. The direct evidence of the coil inductance of myelin is the opposite spiraling phenomenon between adjacent myelin sheaths confirmed by previous studies. As for the piezoelectric effect of the cell membrane, which has been well-known in physics, the direct evidence is the mechanical wave accompany with action potential. Therefore, a more complete physical nature of neural signals is provided. In conventional neuroscience, the neural signal is a pure electrical signal. In our new theory, the neural signal is an energy pulse containing electrical, magnetic, and mechanical components. Such a physical understanding of the neural signal and neural systems significantly improve the knowledge of the neurons. On the one hand, we achieve a corrected neural circuit of an inductor-capacitor-capacitor (LCC) form, whose frequency response and electrical characteristics have been validated by previous studies and the modeling fitting of artifacts in our experiments. On the other hand, a number of phenomena observed in neural experiments are explained. In particular, they are the mechanism of magnetic nerve stimulations and ultrasound nerve stimulations, the MRI image contrast issue and Anode Break Excitation. At last, the biological function of myelin is summarized. It is to provide inductance in the process of neural signal, which can enhance the signal speed in peripheral nervous systems and provide frequency modulation function in central nervous systems.
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Affiliation(s)
- Hao Wang
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jiahui Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Guangyi Cai
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yonghong Liu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yansong Qu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Tianzhun Wu
- Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China.,Key Laboratory of Health Bioinformatics, Chinese Academy of Sciences, Shenzhen, China
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17
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Del Corso G, Verzicco R, Viola F. Sensitivity analysis of an electrophysiology model for the left ventricle. J R Soc Interface 2020; 17:20200532. [PMID: 33109017 DOI: 10.1098/rsif.2020.0532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Modelling the cardiac electrophysiology entails dealing with the uncertainties related to the input parameters such as the heart geometry and the electrical conductivities of the tissues, thus calling for an uncertainty quantification (UQ) of the results. Since the chambers of the heart have different shapes and tissues, in order to make the problem affordable, here we focus on the left ventricle with the aim of identifying which of the uncertain inputs mostly affect its electrophysiology. In a first phase, the uncertainty of the input parameters is evaluated using data available from the literature and the output quantities of interest (QoIs) of the problem are defined. According to the polynomial chaos expansion, a training dataset is then created by sampling the parameter space using a quasi-Monte Carlo method whereas a smaller independent dataset is used for the validation of the resulting metamodel. The latter is exploited to run a global sensitivity analysis with nonlinear variance-based indices and thus reduce the input parameter space accordingly. Thereafter, the uncertainty probability distribution of the QoIs are evaluated using a direct UQ strategy on a larger dataset and the results discussed in the light of the medical knowledge.
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Affiliation(s)
| | - Roberto Verzicco
- Gran Sasso Science Institute (GSSI), L'Aquila, Italy.,University of Rome Tor Vergata, Rome, Italy.,POF Group, University of Twente, Enschede, The Netherlands
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18
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Eles JR, Stieger KC, Kozai TDY. The temporal pattern of Intracortical Microstimulation pulses elicits distinct temporal and spatial recruitment of cortical neuropil and neurons. J Neural Eng 2020; 18. [PMID: 33075762 DOI: 10.1088/1741-2552/abc29c] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 10/19/2020] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The spacing or distribution of stimulation pulses of therapeutic neurostimulation waveforms-referred to here as the Temporal Pattern (TP)-has emerged as an important parameter for tuning the response to deep-brain stimulation and intracortical microstimulation (ICMS). While it has long been assumed that modulating the TP of ICMS may be effective by altering the rate coding of the neural response, it is unclear how it alters the neural response at the neural network level. The present study is designed to elucidate the neural response to TP at the network level. APPROACH We use in vivo two-photon imaging of ICMS in mice expressing the calcium sensor Thy1-GCaMP or the glutamate sensor hSyn-iGluSnFr to examine the layer II/III neural response to stimulations with different TPs. We study the neuronal calcium and glutamate response to TPs with the same average frequency (10Hz) and same total charge injection, but varying degrees of bursting. We also investigate one control pattern with an average frequency of 100Hz and 10X the charge injection. MAIN RESULTS Stimulation trains with the same average frequency (10 Hz) and same total charge injection but distinct temporal patterns recruits distinct sets of neurons. More-than-half (60% of 309 cells) prefer one temporal pattern over the other. Despite their distinct spatial recruitment patterns, both cells exhibit similar ability to follow 30s trains of both TPs without failing, and they exhibit similar levels of glutamate release during stimulation. Both neuronal calcium and glutamate release train to the bursting TP pattern (~21-fold increase in relative power at the frequency of bursting. Bursting also results in a statistically significant elevation in the correlation between somatic calcium activity and neuropil activity, which we explore as a metric for inhibitory-excitatory tone. Interestingly, soma-neuropil correlation during the bursting pattern is a statistically significant predictor of cell preference for TP, which exposes a key link between inhibitory-excitatory tone. Finally, using mesoscale imaging, we show that both TPs result in distal inhibition during stimulation, which reveals complex spatial and temporal interactions between temporal pattern and inhibitory-excitatory tone in ICMS. SIGNIFICANCE Our results may ultimately suggest that TP is a valuable parameter space to modulate inhibitory-excitatory tone as well as distinct network activity in ICMS. This presents a broader mechanism of action than rate coding, as previously thought. By implicating these additional mechanisms, TP may have broader utility in the clinic and should be pursued to expand the efficacy of ICMS therapies.
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Affiliation(s)
- James R Eles
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, UNITED STATES
| | - Kevin C Stieger
- Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, UNITED STATES
| | - Takashi D Yoshida Kozai
- Department of Bioengineering, University of Pittsburgh, 3501 Fifth Ave, 5059-BST3, Pittsburgh, PA 15213, USA, Pittsburgh, Pennsylvania, UNITED STATES
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19
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Chiou YA, Cheng LK, Lin SF. Effects of high-frequency biphasic shocks on ventricular vulnerability and defibrillation outcomes through synchronized virtual electrode responses. PLoS One 2020; 15:e0232529. [PMID: 32357163 PMCID: PMC7194403 DOI: 10.1371/journal.pone.0232529] [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: 10/30/2019] [Accepted: 04/16/2020] [Indexed: 11/19/2022] Open
Abstract
Electrical defibrillation is a well-established treatment for cardiac dysrhythmias. Studies have suggested that shock-induced spatial sawtooth patterns and virtual electrodes are responsible for defibrillation efficacy. We hypothesize that high-frequency shocks enhance defibrillation efficacy by generating temporal sawtooth patterns and using rapid virtual electrodes synchronized with shock frequency. High-speed optical mapping was performed on isolated rat hearts at 2000 frames/s. Two defibrillation electrodes were placed on opposite sides of the ventricles. An S1-S2 pacing protocol was used to induce ventricular tachyarrhythmia (VTA). High-frequency shocks of equal energy but varying frequencies of 125–1000 Hz were used to evaluate VTA vulnerability and defibrillation success rate. The 1000-Hz shock had the highest VTA induction rate in the shorter S1-S2 intervals (50 and 100 ms) and the highest VTA defibrillation rate (70%) among all frequencies. Temporal sawtooth patterns and synchronous shock-induced virtual electrode responses could be observed with frequencies of up to 1000 Hz. The improved defibrillation outcome with high-frequency shocks suggests a lower energy requirement than that of low-frequency shocks for successful ventricular defibrillation.
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Affiliation(s)
- Yu-An Chiou
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu, Taiwan
| | - Li-Kuan Cheng
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu, Taiwan
| | - Shien-Fong Lin
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu, Taiwan
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu, Taiwan
- * E-mail:
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20
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Shibata N, Inada S, Nakazawa K, Tomii N, Yamazaki M, Seno H, Honjo H, Sakuma I. Mechanism of Electrical Defibrillation: Current Status and Future Perspective. ADVANCED BIOMEDICAL ENGINEERING 2020. [DOI: 10.14326/abe.9.125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Nitaro Shibata
- Department of Cardiology, Shinjuku Mitsui Building Clinic
| | - Shin Inada
- Faculty of Health Sciences, Morinomiya University of Medical Sciences
| | - Kazuo Nakazawa
- Faculty of Health Sciences, Morinomiya University of Medical Sciences
| | - Naoki Tomii
- Department of Bioengineering, The University of Tokyo
| | | | - Hiroshi Seno
- Department of Bioengineering, The University of Tokyo
| | - Haruo Honjo
- Research Institute of Environmental Medicine, Nagoya University
| | - Ichiro Sakuma
- Department of Bioengineering, The University of Tokyo
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21
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Moreno A, Walton RD, Constantin M, Bernus O, Vigmond EJ, Bayer JD. Wide-area low-energy surface stimulation of large mammalian ventricular tissue. Sci Rep 2019; 9:15863. [PMID: 31676789 PMCID: PMC6825186 DOI: 10.1038/s41598-019-51364-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/30/2019] [Indexed: 11/09/2022] Open
Abstract
The epicardial and endocardial surfaces of the heart are attractive targets to administer antiarrhythmic electrotherapies. Electrically stimulating wide areas of the surfaces of small mammalian ventricles is straightforward given the relatively small scale of their myocardial dimensions compared to the tissue space constant and electrical field. However, it has yet to be proven for larger mammalian hearts with tissue properties and ventricular dimensions closer to humans. Our goal was to address the feasibility and impact of wide-area electrical stimulation on the ventricular surfaces of large mammalian hearts at different stimulus strengths. This was accomplished by placing long line electrodes on the ventricular surfaces of pig hearts that span wide areas, and activating them individually. Stimulus efficacy was assessed and compared between surfaces, and tissue viability was evaluated. Activation time was dependent on stimulation strength and location, achieving uniform linear stimulation at 9x threshold strength. Endocardial stimulation activated more tissue transmurally than epicardial stimulation, which could be considered a potential target for future cardiac electrotherapies. Overall, our results indicate that electrically stimulating wide areas of the ventricular surfaces of large mammals is achievable with line electrodes, minimal tissue damage, and energies under the human pain threshold (100 mJ).
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Affiliation(s)
- Angel Moreno
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France.,Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, UMR5251, Bordeaux, France
| | - Richard D Walton
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France.,Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, U1045, Bordeaux, France.,INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
| | - Marion Constantin
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France.,Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, U1045, Bordeaux, France.,INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
| | - Olivier Bernus
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France.,Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, U1045, Bordeaux, France.,INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
| | - Edward J Vigmond
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France.,Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, UMR5251, Bordeaux, France
| | - Jason D Bayer
- IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université. Pessac, Bordeaux, France. .,Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, UMR5251, Bordeaux, France. .,L'Institut de Rythmologie et Modélisation Cardiaque (LIRYC), Hôpital Xavier Arnozan, Avenue du Haut Lévêque, 33604, Pessac, France.
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22
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Abstract
Optical mapping of electrical activity in the heart is based on voltage-sensitive and lipophilic fluorescence dyes. Optical signals recorded from cardiac cells correlate well with their transmembrane potentials. High spatiotemporal resolution, wide field mapping, and high sensitivity to transmembrane potential enable detailed characterization of action potential initiation and propagation. Optical mapping is used to study complex patterns of excitation propagation, including propagation across the sinoatrial and atrioventricular nodes and during atrial and ventricular arrhythmias.Optical mapping is used to study the role of reentrant activity in atrial and ventricular fibrillation.
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23
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Funken M, Malan D, Sasse P, Bruegmann T. Optogenetic Hyperpolarization of Cardiomyocytes Terminates Ventricular Arrhythmia. Front Physiol 2019; 10:498. [PMID: 31105593 PMCID: PMC6491897 DOI: 10.3389/fphys.2019.00498] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/08/2019] [Indexed: 01/04/2023] Open
Abstract
Cardiac defibrillation to terminate lethal ventricular arrhythmia (VA) is currently performed by applying high energy electrical shocks. In cardiac tissue, electrical shocks induce simultaneously de- and hyperpolarized areas and only depolarized areas are considered to be responsible for VA termination. Because electrical shocks do not allow proper control over spatial extent and level of membrane potential changes, the effects of hyperpolarization have not been explored in the intact heart. In contrast, optogenetic methods allow cell type-selective induction of de- and hyperpolarization with unprecedented temporal and spatial control. To investigate effects of cardiomyocyte hyperpolarization on VA termination, we generated a mouse line with cardiomyocyte-specific expression of the light-driven proton pump ArchT. Isolated cardiomyocytes showed light-induced outward currents and hyperpolarization. Free-running VA were evoked by electrical stimulation of explanted hearts perfused with low K+ and the KATP channel opener Pinacidil. Optogenetic hyperpolarization was induced by epicardial illumination, which terminated VA with an average efficacy of ∼55%. This value was significantly higher compared to control hearts without illumination or ArchT expression (p = 0.0007). Intracellular recordings with sharp electrodes within the intact heart revealed hyperpolarization and faster action potential upstroke upon illumination, which should fasten conduction. However, conduction speed was lower during illumination suggesting enhanced electrical sink by hyperpolarization underlying VA termination. Thus, selective hyperpolarization in cardiomyocytes is able to terminate VA with a completely new mechanism of increased electrical sink. These novel insights could improve our mechanistic understanding and treatment strategies of VA termination.
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Affiliation(s)
- Maximilian Funken
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Department of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Daniela Malan
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Research Training Group 1873, University of Bonn, Bonn, Germany.,Institute of Cardiovascular Physiology, University Medical Center, Georg-August-University Göttingen, Göttingen, Germany.,DZHK (German Research Centre for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
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24
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Love MR, Sripetchwandee J, Palee S, Chattipakorn SC, Mower MM, Chattipakorn N. Effects of biphasic and monophasic electrical stimulation on mitochondrial dynamics, cell apoptosis, and cell proliferation. J Cell Physiol 2018; 234:816-824. [PMID: 30078226 DOI: 10.1002/jcp.26897] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/13/2018] [Indexed: 12/20/2022]
Abstract
Currently, electrical stimulation (ES) is used to induce changes in various tissues and cellular processes, but its effects on mitochondrial dynamics and mechanisms are unknown. The aim of this study was to compare the effects of monophasic and biphasic, anodal, and cathodal ES on apoptosis, proliferation, and mitochondrial dynamics in neuroblastoma SH-SY5Y cells. Cells were cultured and treated with ES. Alamar blue assay was performed to measure cell proliferation. The proteins expression of apoptotic-related proteins Bcl-2 associated X (Bax), B cell lymphoma 2 (Bcl-2), optic-atrophy-1 (OPA1), mitofusin2 (Mfn2), phosphorylated dynamin-related protein 1 at serine 616 (p-DRP1), and total dynamin-related protein 1 (Total-DRP1) were also determined. The results showed that monophasic anodal and biphasic anodal/cathodal (Bi Anod) ES for 1 hr at 125 pulses per minute (2.0 Hz) produced the most significant increase in cell proliferation. In addition, monophasic anodal and Bi Anod ES treated cells displayed a significant increase in the levels of anti-apoptotic protein Bcl-2, whereas the Bax levels were not changed. Moreover, the levels of Mfn2 were increased in the cells treated by Bi Anod, and OPA1 was increased by monophasic anodal and Bi Anod ES, indicating increased mitochondrial fusion in these ES-treated cells. However, the levels of mitochondrial fission indicated by DRP1 remained unchanged compared with non-stimulated cells. These findings were confirmed through visualization of mitochondria using Mitotracker Deep Red, demonstrating that monophasic anodal and Bi Anod ES could induce pro-survival effects in SH-SY5Y cells through increasing cell proliferation and mitochondrial fusion. Future research is needed to validate these findings for the clinical application of monophasic anodal and Bi Anod ES.
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Affiliation(s)
- Maria R Love
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Faculty of Biological Sciences, The University of Manchester, Manchester, United Kingdom
| | - Jirapas Sripetchwandee
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand
| | - Siripong Palee
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand
| | - Siriporn C Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand.,Department of Oral Biology and Diagnostic Science, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand
| | - Morton M Mower
- Department of Medicine, University of Colorado, Denver, Colorado
| | - Nipon Chattipakorn
- Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai, Thailand
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Tomii N, Yamazaki M, Arafune T, Kamiya K, Nakazawa K, Honjo H, Shibata N, Sakuma I. Interaction of phase singularities on the spiral wave tail: reconsideration of capturing the excitable gap. Am J Physiol Heart Circ Physiol 2018. [DOI: 10.1152/ajpheart.00558.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The action mechanism of stimulation toward spiral waves (SWs) owing to the complex excitation patterns that occur just after point stimulation has not yet been experimentally clarified. This study sought to test our hypothesis that the effect of capturing excitable gap of SWs by stimulation can also be explained as the interaction of original phase singularity (PS) and PSs induced by the stimulation on the wave tail (WT) of the original SW. Phase variance analysis was used to quantitatively analyze the postshock PS trajectories. In a two-dimensional subepicardial layer of Langendorff-perfused rabbit hearts, optical mapping was used to record the excitation pattern during stimulation. After a SW was induced by S1–S2 shock, single biphasic point stimulation S3 was applied. In 70 of the S1-S2-S3 stimulation episodes applied on 6 hearts, the original PS was clearly observed just before the S3 point stimulation in 37 episodes. Pairwise PSs were newly induced by the S3 in 20 episodes. The original PS collided with the newly induced PSs in 16 episodes; otherwise, they did not interact with the original PS. SW shift occurred most efficiently when the S3 shock was applied at the relative refractory period, and PS shifted in the direction of the WT. In conclusion, quantitative tracking of PS clarified that stimulation in desirable conditions induces pairwise PSs on WT and that the collision of PSs causes SW shift along the WT. The results of this study indicate the importance of the interaction of shock-induced excitation with the WT for effective stimulation. NEW & NOTEWORTHY The quantitative analysis of spiral wave dynamics during stimulation clarified the action mechanism of capturing the excitable gap, i.e., the induction of pairwise phase singularities on the wave tail and spiral wave shift along the wave tail as a result of these interactions. The importance of the wave tail for effective stimulation was revealed.
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Affiliation(s)
- Naoki Tomii
- Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Tatsuhiko Arafune
- Department of Science and Engineering, Tokyo Denki University, Tokyo, Japan
| | - Kaichiro Kamiya
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Kazuo Nakazawa
- National Cerebral and Cardiovascular Research Center, Osaka, Japan
| | - Haruo Honjo
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | | | - Ichiro Sakuma
- Department of Engineering, The University of Tokyo, Tokyo, Japan
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Pathmanathan P, Gray RA. Validation and Trustworthiness of Multiscale Models of Cardiac Electrophysiology. Front Physiol 2018; 9:106. [PMID: 29497385 PMCID: PMC5818422 DOI: 10.3389/fphys.2018.00106] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/31/2018] [Indexed: 02/06/2023] Open
Abstract
Computational models of cardiac electrophysiology have a long history in basic science applications and device design and evaluation, but have significant potential for clinical applications in all areas of cardiovascular medicine, including functional imaging and mapping, drug safety evaluation, disease diagnosis, patient selection, and therapy optimisation or personalisation. For all stakeholders to be confident in model-based clinical decisions, cardiac electrophysiological (CEP) models must be demonstrated to be trustworthy and reliable. Credibility, that is, the belief in the predictive capability, of a computational model is primarily established by performing validation, in which model predictions are compared to experimental or clinical data. However, there are numerous challenges to performing validation for highly complex multi-scale physiological models such as CEP models. As a result, credibility of CEP model predictions is usually founded upon a wide range of distinct factors, including various types of validation results, underlying theory, evidence supporting model assumptions, evidence from model calibration, all at a variety of scales from ion channel to cell to organ. Consequently, it is often unclear, or a matter for debate, the extent to which a CEP model can be trusted for a given application. The aim of this article is to clarify potential rationale for the trustworthiness of CEP models by reviewing evidence that has been (or could be) presented to support their credibility. We specifically address the complexity and multi-scale nature of CEP models which makes traditional model evaluation difficult. In addition, we make explicit some of the credibility justification that we believe is implicitly embedded in the CEP modeling literature. Overall, we provide a fresh perspective to CEP model credibility, and build a depiction and categorisation of the wide-ranging body of credibility evidence for CEP models. This paper also represents a step toward the extension of model evaluation methodologies that are currently being developed by the medical device community, to physiological models.
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Affiliation(s)
- Pras Pathmanathan
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
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27
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Buran P, Bär M, Alonso S, Niedermayer T. Control of electrical turbulence by periodic excitation of cardiac tissue. CHAOS (WOODBURY, N.Y.) 2017; 27:113110. [PMID: 29195336 DOI: 10.1063/1.5010787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Electrical turbulence in cardiac tissue is associated with arrhythmias such as life-threatening ventricular fibrillation. Recent experimental studies have shown that a sequence of low-energy electrical far-field pulses is able to terminate fibrillation more gently than a single high-energy pulse which causes severe side effects. During this low-energy antifibrillation pacing (LEAP), only tissue near sufficiently large conduction heterogeneities, such as large coronary arteries, is activated. In order to optimize LEAP, we performed extensive simulations of cardiac tissue perforated by blood vessels, employing two alternative cellular models that exhibit electrical turbulence at a similar length scale. Moreover, the scale of blood vessels in our two-dimensional simulations was chosen such that the threshold for single pulse defibrillation matches experimental values. For each of the 100 initial conditions, we tested different electrical field strengths, pulse shapes, numbers of pulses, and periods between the pulses. LEAP is successful for both models, albeit with substantial differences. One model exhibits a spectrum of chaotic activity featuring a narrow peak around a dominant frequency. In this case, the optimal period between low-energy pulses matches this frequency and LEAP greatly reduces the required energy for successful defibrillation. For pulses with larger energies, the system is perturbed such that underdrive pacing becomes advantageous. The spectrum of the second model features a broader peak, resulting in a less pronounced optimal pacing period and a decreased energy reduction. In both cases, pacing with five or six pulses which are separated by the dominant period maximizes the energy reduction.
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Affiliation(s)
- Pavel Buran
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany
| | - Markus Bär
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany
| | - Sergio Alonso
- Department of Physics, Universitat Politècnica de Catalunya, Av. Dr. Marañón 44, 08028 Barcelona, Spain
| | - Thomas Niedermayer
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany
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28
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Galappaththige SK, Gray RA, Roth BJ. Modeling bipolar stimulation of cardiac tissue. CHAOS (WOODBURY, N.Y.) 2017; 27:093920. [PMID: 28964126 PMCID: PMC5577008 DOI: 10.1063/1.5000163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
Unipolar stimulation of cardiac tissue is often used in the design of cardiac pacemakers because of the low current required to depolarize the surrounding tissue at rest. However, the advantages of unipolar over bipolar stimulation are not obvious at shorter coupling intervals when the tissue near the pacing electrode is relatively refractory. Therefore, this paper analyzes bipolar stimulation of cardiac tissue. The strength-interval relationship for bipolar stimulation is calculated using the bidomain model and a recently developed parsimonious ionic current model. The strength-interval curves obtained using different electrode separations and arrangements (electrodes placed parallel to the fibers versus perpendicular to the fibers) indicate that bipolar stimulation results in more complex activation patterns compared to unipolar stimulation. An unusually low threshold stimulus current is observed when the electrodes are close to each other (a separation of 1 mm) because of break excitation. Unlike for unipolar stimulation, anode make excitation is not present during bipolar stimulation, and an abrupt switch from anode break to cathode make excitation can cause dramatic changes in threshold with very small changes in the interval. These results could impact the design of implantable pacemakers and defibrillators.
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Affiliation(s)
| | - Richard A Gray
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland 20993, USA
| | - Bradley J Roth
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
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29
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Rossi S, Griffith BE. Incorporating inductances in tissue-scale models of cardiac electrophysiology. CHAOS (WOODBURY, N.Y.) 2017; 27:093926. [PMID: 28964127 PMCID: PMC5585078 DOI: 10.1063/1.5000706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/17/2017] [Indexed: 06/07/2023]
Abstract
In standard models of cardiac electrophysiology, including the bidomain and monodomain models, local perturbations can propagate at infinite speed. We address this unrealistic property by developing a hyperbolic bidomain model that is based on a generalization of Ohm's law with a Cattaneo-type model for the fluxes. Further, we obtain a hyperbolic monodomain model in the case that the intracellular and extracellular conductivity tensors have the same anisotropy ratio. In one spatial dimension, the hyperbolic monodomain model is equivalent to a cable model that includes axial inductances, and the relaxation times of the Cattaneo fluxes are strictly related to these inductances. A purely linear analysis shows that the inductances are negligible, but models of cardiac electrophysiology are highly nonlinear, and linear predictions may not capture the fully nonlinear dynamics. In fact, contrary to the linear analysis, we show that for simple nonlinear ionic models, an increase in conduction velocity is obtained for small and moderate values of the relaxation time. A similar behavior is also demonstrated with biophysically detailed ionic models. Using the Fenton-Karma model along with a low-order finite element spatial discretization, we numerically analyze differences between the standard monodomain model and the hyperbolic monodomain model. In a simple benchmark test, we show that the propagation of the action potential is strongly influenced by the alignment of the fibers with respect to the mesh in both the parabolic and hyperbolic models when using relatively coarse spatial discretizations. Accurate predictions of the conduction velocity require computational mesh spacings on the order of a single cardiac cell. We also compare the two formulations in the case of spiral break up and atrial fibrillation in an anatomically detailed model of the left atrium, and we examine the effect of intracellular and extracellular inductances on the virtual electrode phenomenon.
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Affiliation(s)
- Simone Rossi
- Department of Mathematics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Boyce E Griffith
- Departments of Mathematics and Biomedical Engineering and McAllister Heart Institute, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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30
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Ji YC, Uzelac I, Otani N, Luther S, Gilmour RF, Cherry EM, Fenton FH. Synchronization as a mechanism for low-energy anti-fibrillation pacing. Heart Rhythm 2017; 14:1254-1262. [DOI: 10.1016/j.hrthm.2017.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Indexed: 10/19/2022]
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31
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Zhang M, Guo B. Electroactive 3D Scaffolds Based on Silk Fibroin and Water-Borne Polyaniline for Skeletal Muscle Tissue Engineering. Macromol Biosci 2017; 17. [DOI: 10.1002/mabi.201700147] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/23/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Mengyao Zhang
- Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Baolin Guo
- Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
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32
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Cardiac strength-interval curves calculated using a bidomain tissue with a parsimonious ionic current. PLoS One 2017; 12:e0171144. [PMID: 28222136 PMCID: PMC5319764 DOI: 10.1371/journal.pone.0171144] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 01/13/2017] [Indexed: 11/19/2022] Open
Abstract
The strength-interval curve plays a major role in understanding how cardiac tissue responds to an electrical stimulus. This complex behavior has been studied previously using the bidomain formulation incorporating the Beeler-Reuter and Luo-Rudy dynamic ionic current models. The complexity of these models renders the interpretation and extrapolation of simulation results problematic. Here we utilize a recently developed parsimonious ionic current model with only two currents—a sodium current that activates rapidly upon depolarization INa and a time-independent inwardly rectifying repolarization current IK—which reproduces many experimentally measured action potential waveforms. Bidomain tissue simulations with this ionic current model reproduce the distinctive dip in the anodal (but not cathodal) strength-interval curve. Studying model variants elucidates the necessary and sufficient physiological conditions to predict the polarity dependent dip: a voltage and time dependent INa, a nonlinear rectifying repolarization current, and bidomain tissue with unequal anisotropy ratios.
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33
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Rossi S, Buccarello A, Ershler PR, Lux RL, Callegari S, Corradi D, Carnevali L, Sgoifo A, Miragoli M, Musso E, Macchi E. Effect of anisotropy on ventricular vulnerability to unidirectional block and reentry by single premature stimulation during normal sinus rhythm in rat heart. Am J Physiol Heart Circ Physiol 2016; 312:H584-H607. [PMID: 28011584 DOI: 10.1152/ajpheart.00366.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 12/05/2016] [Accepted: 12/20/2016] [Indexed: 11/22/2022]
Abstract
Single high-intensity premature stimuli when applied to the ventricles during ventricular drive of an ectopic site, as in Winfree's "pinwheel experiment," usually induce reentry arrhythmias in the normal heart, while single low-intensity stimuli barely do. Yet ventricular arrhythmia vulnerability during normal sinus rhythm remains largely unexplored. With a view to define the role of anisotropy on ventricular vulnerability to unidirectional conduction block and reentry, we revisited the pinwheel experiment with reduced constraints in the in situ rat heart. New features included single premature stimulation during normal sinus rhythm, stimulation and unipolar potential mapping from the same high-resolution epicardial electrode array, and progressive increase in stimulation strength and prematurity from diastolic threshold until arrhythmia induction. Measurements were performed with 1-ms cathodal stimuli at multiple test sites (n = 26) in seven rats. Stimulus-induced virtual electrode polarization during sinus beat recovery phase influenced premature ventricular responses. Specifically, gradual increase in stimulus strength and prematurity progressively induced make, break, and graded-response stimulation mechanisms. Hence unidirectional conduction block occurred as follows: 1) along fiber direction, on right and left ventricular free walls (n = 23), initiating figure-eight reentry (n = 17) and tachycardia (n = 12), and 2) across fiber direction, on lower interventricular septum (n = 3), initiating spiral wave reentry (n = 2) and tachycardia (n = 1). Critical time window (55.1 ± 4.7 ms, 68.2 ± 6.0 ms) and stimulus strength lower limit (4.9 ± 0.6 mA) defined vulnerability to reentry. A novel finding of this study was that ventricular tachycardia evolves and is maintained by episodes of scroll-like wave and focal activation couplets. We also found that single low-intensity premature stimuli can induce repetitive ventricular response (n = 13) characterized by focal activations.NEW & NOTEWORTHY We performed ventricular cathodal point stimulation during sinus rhythm by progressively increasing stimulus strength and prematurity. Virtual electrode polarization and recovery gradient progressively induced make, break, and graded-response stimulation mechanisms. Unidirectional conduction block occurred along or across fiber direction, initiating figure-eight or spiral wave reentry, respectively, and tachycardia sustained by scroll wave and focal activations.
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Affiliation(s)
- S Rossi
- Department of Life Sciences, Università degli Studi, Parma, Italy.,CERT, Center of Excellence for Toxicological Research, Department of Clinical and Experimental Medicine, Università degli Studi, Parma, Italy
| | - A Buccarello
- Department of Life Sciences, Università degli Studi, Parma, Italy
| | - P R Ershler
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - R L Lux
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - S Callegari
- Azienda Unità Sanitaria Locale, Unit of Cardiology, Parma, Italy
| | - D Corradi
- Department of Biomedical, Biotechnological, and Translational Sciences, Unit of Pathology, Università degli Studi, Parma, Italy.,CERT, Center of Excellence for Toxicological Research, Department of Clinical and Experimental Medicine, Università degli Studi, Parma, Italy
| | - L Carnevali
- Department of Life Sciences, Università degli Studi, Parma, Italy
| | - A Sgoifo
- Department of Life Sciences, Università degli Studi, Parma, Italy
| | - M Miragoli
- CERT, Center of Excellence for Toxicological Research, Department of Clinical and Experimental Medicine, Università degli Studi, Parma, Italy.,Humanitas Clinical and Research Center, Rozzano (Milan), Italy; and
| | - E Musso
- Department of Life Sciences, Università degli Studi, Parma, Italy.,Cardiac Stem Cell Interdepartmental Center "CISTAC," Università degli Studi, Parma, Italy
| | - E Macchi
- Department of Life Sciences, Università degli Studi, Parma, Italy; .,CERT, Center of Excellence for Toxicological Research, Department of Clinical and Experimental Medicine, Università degli Studi, Parma, Italy.,Cardiac Stem Cell Interdepartmental Center "CISTAC," Università degli Studi, Parma, Italy
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DANDAMUDI GOPI, VIJAYARAMAN PUGAZHENDHI. The Complexity of the His Bundle: Understanding Its Anatomy and Physiology through the Lens of the Past and the Present. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2016; 39:1294-1297. [DOI: 10.1111/pace.12925] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 07/18/2016] [Accepted: 07/20/2016] [Indexed: 12/01/2022]
Affiliation(s)
- GOPI DANDAMUDI
- Indiana University School of Medicine; Indianapolis Indiana
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35
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Oyama MA, Hezzell MJ, Laughlin DS, Thorn CL, Kraus MS, Gelzer AR. Anodal stimulation in two dogs with transvenous permanent bipolar pacemakers. J Vet Cardiol 2016; 18:398-404. [PMID: 27613649 DOI: 10.1016/j.jvc.2016.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/05/2016] [Accepted: 07/24/2016] [Indexed: 11/20/2022]
Abstract
Management of symptomatic bradyarrhythmias such as complete atrioventricular block often involves permanent implantation of a transvenous pacemaker. Both during and after implantation, the operator can telemetrically assess and adjust a variety of electrical parameters associated with the pacemaker function in order to optimize the sensitivity, reliability, and power consumption of the device. Herein, we report an unexpected change in the paced electrocardiographic QRS complex morphology in two dogs undergoing bipolar pacing associated with changes in the pacemaker output amplitude settings first detected during threshold testing. The exclusivity of the electrocardiographic changes solely on pacemaker output settings, consistency between the surface electrocardiogram and ventricular endocardial electrogram, and resolution of this phenomenon when dogs were re-programmed to unipolar pacing is consistent with depolarization of the ventricular myocardium by the anodal electrode of the pacing lead at high pacemaker amplitudes. Anodal stimulation is a potential cause of varying QRS complex morphology witnessed during pacemaker evaluation and interrogation.
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Affiliation(s)
- M A Oyama
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA.
| | - M J Hezzell
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA
| | - D S Laughlin
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA
| | - C L Thorn
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA
| | - M S Kraus
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA
| | - A R Gelzer
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey St., Philadelphia, PA 19104, USA
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36
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Tomii N, Yamazaki M, Arafune T, Honjo H, Shibata N, Sakuma I. Detection Algorithm of Phase Singularity Using Phase Variance Analysis for Epicardial Optical Mapping Data. IEEE Trans Biomed Eng 2016; 63:1795-1803. [DOI: 10.1109/tbme.2015.2502726] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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37
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Alonso S, Bär M, Echebarria B. Nonlinear physics of electrical wave propagation in the heart: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096601. [PMID: 27517161 DOI: 10.1088/0034-4885/79/9/096601] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The beating of the heart is a synchronized contraction of muscle cells (myocytes) that is triggered by a periodic sequence of electrical waves (action potentials) originating in the sino-atrial node and propagating over the atria and the ventricles. Cardiac arrhythmias like atrial and ventricular fibrillation (AF,VF) or ventricular tachycardia (VT) are caused by disruptions and instabilities of these electrical excitations, that lead to the emergence of rotating waves (VT) and turbulent wave patterns (AF,VF). Numerous simulation and experimental studies during the last 20 years have addressed these topics. In this review we focus on the nonlinear dynamics of wave propagation in the heart with an emphasis on the theory of pulses, spirals and scroll waves and their instabilities in excitable media with applications to cardiac modeling. After an introduction into electrophysiological models for action potential propagation, the modeling and analysis of spatiotemporal alternans, spiral and scroll meandering, spiral breakup and scroll wave instabilities like negative line tension and sproing are reviewed in depth and discussed with emphasis on their impact for cardiac arrhythmias.
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Affiliation(s)
- Sergio Alonso
- Physikalisch-Technische Bundesanstalt, Abbestr. 2-12 10587, Berlin, Germany. Department of Physics, Universitat Politècnica de Catalunya, Av. Dr. Marañón 44, E-08028 Barcelona, Spain
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38
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Xu Y, Guan J. Biomaterial property-controlled stem cell fates for cardiac regeneration. Bioact Mater 2016; 1:18-28. [PMID: 29744392 PMCID: PMC5883968 DOI: 10.1016/j.bioactmat.2016.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/17/2016] [Accepted: 03/19/2016] [Indexed: 12/13/2022] Open
Abstract
Myocardial infarction (MI) affects more than 8 million people in the United States alone. Due to the insufficient regeneration capacity of the native myocardium, one widely studied approach is cardiac tissue engineering, in which cells are delivered with or without biomaterials and/or regulatory factors to fully regenerate the cardiac functions. Specifically, in vitro cardiac tissue engineering focuses on using biomaterials as a reservoir for cells to attach, as well as a carrier of various regulatory factors such as growth factors and peptides, providing high cell retention and a proper microenvironment for cells to migrate, grow and differentiate within the scaffolds before implantation. Many studies have shown that the full establishment of a functional cardiac tissue in vitro requires synergistic actions between the seeded cells, the tissue culture condition, and the biochemical and biophysical environment provided by the biomaterials-based scaffolds. Proper electrical stimulation and mechanical stretch during the in vitro culture can induce the ordered orientation and differentiation of the seeded cells. On the other hand, the various scaffolds biochemical and biophysical properties such as polymer composition, ligand concentration, biodegradability, scaffold topography and mechanical properties can also have a significant effect on the cellular processes. Cell therapy is an attractive approach for cardiac regeneration after myocardial infarction. Biomaterials are used as cell carriers. This review highlights how biochemical and biophysical properties of biomaterials affect cell fates.
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Affiliation(s)
- Yanyi Xu
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
| | - Jianjun Guan
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
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39
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Shalbaf F, Du P, Lovell NH, Dokos S, Vaghefi E. A 3D-continuum bidomain model of retinal electrical stimulation using an anatomically detailed mesh. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:2291-4. [PMID: 26736750 DOI: 10.1109/embc.2015.7318850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A continuum bidomain model of sub-retinal electrical stimulation on an anatomically detailed mesh of retina is presented. The underlying geometry is made up of 256 B-scans of optical coherence tomography (OCT) images of a healthy human retina, covering approximately 6×2 mm(2) centered on the macula. The OCT images are initially segmented and digitized into five major retinal layers comprising passive and active retinal cell types. This computational mesh is then used to model a subretinal hexapolar biphasic electrical stimulation. Our results indicate that the ultra-structure of the retina results in an asymmetric spatial extracellular potential distribution, leading to an irregular pattern of retinal ganglion cell activation. This finding is in contrast to focal circular activation previously reported in retinal electrical stimulation modeling with a uniform mesh.
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40
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Yin PT, Han E, Lee KB. Engineering Stem Cells for Biomedical Applications. Adv Healthc Mater 2016; 5:10-55. [PMID: 25772134 PMCID: PMC5810416 DOI: 10.1002/adhm.201400842] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/14/2015] [Indexed: 12/19/2022]
Abstract
Stem cells are characterized by a number of useful properties, including their ability to migrate, differentiate, and secrete a variety of therapeutic molecules such as immunomodulatory factors. As such, numerous pre-clinical and clinical studies have utilized stem cell-based therapies and demonstrated their tremendous potential for the treatment of various human diseases and disorders. Recently, efforts have focused on engineering stem cells in order to further enhance their innate abilities as well as to confer them with new functionalities, which can then be used in various biomedical applications. These engineered stem cells can take on a number of forms. For instance, engineered stem cells encompass the genetic modification of stem cells as well as the use of stem cells for gene delivery, nanoparticle loading and delivery, and even small molecule drug delivery. The present Review gives an in-depth account of the current status of engineered stem cells, including potential cell sources, the most common methods used to engineer stem cells, and the utilization of engineered stem cells in various biomedical applications, with a particular focus on tissue regeneration, the treatment of immunodeficiency diseases, and cancer.
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Affiliation(s)
- Perry T Yin
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, NJ, 08854, USA
| | - Edward Han
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, M5S 3G9, Canada
| | - Ki-Bum Lee
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, NJ, 08854, USA
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ, 08854, USA
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41
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Xie F, Varghese F, Pakhomov AG, Semenov I, Xiao S, Philpott J, Zemlin C. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields. PLoS One 2015; 10:e0144833. [PMID: 26658139 PMCID: PMC4687652 DOI: 10.1371/journal.pone.0144833] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 11/24/2015] [Indexed: 01/28/2023] Open
Abstract
Background Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations. Methods We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume. Results In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters. Conclusions Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation.
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Affiliation(s)
- Fei Xie
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America.,Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Frency Varghese
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America.,Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Andrei G Pakhomov
- Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Iurii Semenov
- Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Shu Xiao
- Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
| | - Jonathan Philpott
- Department of Surgery, Eastern Virginia Medical School, Norfolk, Virginia, United States of America
| | - Christian Zemlin
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America.,Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America
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42
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Bingen BO, Askar SFA, Neshati Z, Feola I, Panfilov AV, de Vries AAF, Pijnappels DA. Constitutively Active Acetylcholine-Dependent Potassium Current Increases Atrial Defibrillation Threshold by Favoring Post-Shock Re-Initiation. Sci Rep 2015; 5:15187. [PMID: 26487066 PMCID: PMC4613729 DOI: 10.1038/srep15187] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 09/22/2015] [Indexed: 11/10/2022] Open
Abstract
Electrical cardioversion (ECV), a mainstay in atrial fibrillation (AF) treatment, is unsuccessful in up to 10–20% of patients. An important aspect of the remodeling process caused by AF is the constitutive activition of the atrium-specific acetylcholine-dependent potassium current (IK,ACh → IK,ACh-c), which is associated with ECV failure. This study investigated the role of IK,ACh-c in ECV failure and setting the atrial defibrillation threshold (aDFT) in optically mapped neonatal rat cardiomyocyte monolayers. AF was induced by burst pacing followed by application of biphasic shocks of 25–100 V to determine aDFT. Blocking IK,ACh-c by tertiapin significantly decreased DFT, which correlated with a significant increase in wavelength during reentry. Genetic knockdown experiments, using lentiviral vectors encoding a Kcnj5-specific shRNA to modulate IK,ACh-c, yielded similar results. Mechanistically, failed ECV was attributed to incomplete phase singularity (PS) removal or reemergence of PSs (i.e. re-initiation) through unidirectional propagation of shock-induced action potentials. Re-initiation occurred at significantly higher voltages than incomplete PS-removal and was inhibited by IK,ACh-c blockade. Whole-heart mapping confirmed our findings showing a 60% increase in ECV success rate after IK,ACh-c blockade. This study provides new mechanistic insight into failing ECV of AF and identifies IK,ACh-c as possible atrium-specific target to increase ECV effectiveness, while decreasing its harmfulness.
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Affiliation(s)
- Brian O Bingen
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Saïd F A Askar
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Zeinab Neshati
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Iolanda Feola
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands
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43
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Den Hartogh SC, Passier R. Concise Review: Fluorescent Reporters in Human Pluripotent Stem Cells: Contributions to Cardiac Differentiation and Their Applications in Cardiac Disease and Toxicity. Stem Cells 2015; 34:13-26. [DOI: 10.1002/stem.2196] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 07/14/2015] [Accepted: 07/28/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Sabine C. Den Hartogh
- Department of Anatomy and Embryology; Leiden University Medical Centre; Leiden The Netherlands
| | - Robert Passier
- Department of Anatomy and Embryology; Leiden University Medical Centre; Leiden The Netherlands
- Department of Applied Stem cell Technologies. MIRA Institute for Biomedical Technology and Technical Medicine; University of Twente, P.O.Box 217; Enschede The Netherlands
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44
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Esibov A, Chapman FW, Melnick SB, Sullivan JL, Walcott GP. Minor Variations in Electrode Pad Placement Impact Defibrillation Success. PREHOSP EMERG CARE 2015; 20:292-8. [PMID: 26383036 DOI: 10.3109/10903127.2015.1076095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Defibrillation is essential for resuscitating patients with ventricular fibrillation (VF), but shocks often fail to defibrillate. We hypothesized that small variations in pad placement affect shock success, and that defibrillation waveform and shock dose could compensate for suboptimal pad placement. In 10 swine experiments, electrode pads were attached at 3 adjacent anterolateral positions, less than 3 centimeters apart. At each position, 24 episodes of VF were induced and shocked, 8 episodes for each of 3 defibrillation therapies. This resulted in 9 tested combinations of pad position and defibrillation therapy, with 80 episodes of VF for each combination. An episode consisted of 15 seconds of untreated VF, followed by a first shock and, if necessary, a repeat shock. Episodes were separated by four minutes of recovery. Both electrode pad position and therapy order were randomized by experiment. Primary outcome was defined as successful VF termination after the first shock; secondary outcome was the cumulative success of the first and second shocks. First shock efficacy varied widely across the 9 tested combinations of pad position and defibrillation therapy, ranging from 11.3% to 86.3%. When grouped by therapy, first shock efficacy varied significantly between the 3 pad positions: 38.3%, 48.3%, 36.7% (p = 0.02, ANOVA), and, when grouped by pad position, it varied significantly between therapies: 15.0%, 32.5%, 75.8% (p < 0.001, ANOVA). Cumulative 2-shock success varied significantly with therapy (p < 0.001, ANOVA) but not with pad position (p = 0.30, ANOVA). The lowest first shock success was at one position in 6 of 10 animals, at another position in 4 of 10 animals, and never at the third position. Small variations in pad placement can significantly affect defibrillation shock efficacy. However, anatomical variation between individuals and the challenging conditions of real-world resuscitations make optimal pad placement impractical. Suboptimal pad placement can be overcome with defibrillation waveform and shock dose.
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45
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Zaglia T, Pianca N, Borile G, Da Broi F, Richter C, Campione M, Lehnart SE, Luther S, Corrado D, Miquerol L, Mongillo M. Optogenetic determination of the myocardial requirements for extrasystoles by cell type-specific targeting of ChannelRhodopsin-2. Proc Natl Acad Sci U S A 2015; 112:E4495-504. [PMID: 26204914 PMCID: PMC4538656 DOI: 10.1073/pnas.1509380112] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Extrasystoles lead to several consequences, ranging from uneventful palpitations to lethal ventricular arrhythmias, in the presence of pathologies, such as myocardial ischemia. The role of working versus conducting cardiomyocytes, as well as the tissue requirements (minimal cell number) for the generation of extrasystoles, and the properties leading ectopies to become arrhythmia triggers (topology), in the normal and diseased heart, have not been determined directly in vivo. Here, we used optogenetics in transgenic mice expressing ChannelRhodopsin-2 selectively in either cardiomyocytes or the conduction system to achieve cell type-specific, noninvasive control of heart activity with high spatial and temporal resolution. By combining measurement of optogenetic tissue activation in vivo and epicardial voltage mapping in Langendorff-perfused hearts, we demonstrated that focal ectopies require, in the normal mouse heart, the simultaneous depolarization of at least 1,300-1,800 working cardiomyocytes or 90-160 Purkinje fibers. The optogenetic assay identified specific areas in the heart that were highly susceptible to forming extrasystolic foci, and such properties were correlated to the local organization of the Purkinje fiber network, which was imaged in three dimensions using optical projection tomography. Interestingly, during the acute phase of myocardial ischemia, focal ectopies arising from this location, and including both Purkinje fibers and the surrounding working cardiomyocytes, have the highest propensity to trigger sustained arrhythmias. In conclusion, we used cell-specific optogenetics to determine with high spatial resolution and cell type specificity the requirements for the generation of extrasystoles and the factors causing ectopies to be arrhythmia triggers during myocardial ischemia.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/complications
- Arrhythmias, Cardiac/pathology
- Arrhythmias, Cardiac/physiopathology
- Cardiac Complexes, Premature/complications
- Cardiac Complexes, Premature/pathology
- Cardiac Complexes, Premature/physiopathology
- Channelrhodopsins
- Connexins/metabolism
- Coronary Vessels/pathology
- Coronary Vessels/physiopathology
- Electrophysiological Phenomena
- Humans
- Integrases/metabolism
- Ligation
- Male
- Mice, Inbred C57BL
- Mice, Transgenic
- Myocardial Ischemia/complications
- Myocardial Ischemia/pathology
- Myocardial Ischemia/physiopathology
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Optogenetics/methods
- Organ Specificity
- Purkinje Fibers/metabolism
- Purkinje Fibers/pathology
- Purkinje Fibers/physiopathology
- Gap Junction alpha-5 Protein
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Affiliation(s)
- Tania Zaglia
- Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy
| | - Nicola Pianca
- Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy
| | - Giulia Borile
- Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy
| | | | - Claudia Richter
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Gottingen, Germany
| | - Marina Campione
- Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Neuroscience Institute, Consiglio Nazionale delle Ricerche, 35121 Padova, Italy
| | - Stephan E Lehnart
- Heart Research Center Göttingen, Clinic of Cardiology and Pulmonology, University Medical Center, 37077 Gottingen, Germany; German Centre for Cardiovascular Research, partner site Göttingen, 37077 Gottingen, Germany
| | - Stefan Luther
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Gottingen, Germany; Heart Research Center Göttingen, Clinic of Cardiology and Pulmonology, University Medical Center, 37077 Gottingen, Germany; German Centre for Cardiovascular Research, partner site Göttingen, 37077 Gottingen, Germany; Institute for Nonlinear Dynamics, Georg-August-Universität Göttingen, 37077 Gottingen, Germany
| | - Domenico Corrado
- Department of Cardiologic, Thoracic and Vascular Sciences, University of Padova, 35128 Padova, Italy
| | - Lucile Miquerol
- Aix Marseille University, CNRS Institut de Biologie du Développement de Marseille UMR 7288, 13288 Marseille, France
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, 35122 Padova, Italy; Venetian Institute of Molecular Medicine, 35129 Padova, Italy; Neuroscience Institute, Consiglio Nazionale delle Ricerche, 35121 Padova, Italy;
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Optical Imaging of Cardiac Action Potential. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:299-311. [PMID: 26238058 DOI: 10.1007/978-3-319-17641-3_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This chapter reviews the major milestones and scientific achievements facilitated by optical imaging of the action potential in the heart over more than four decades since its introduction. We discuss the limitations of this technique, which sometimes are not fully recognized; the unresolved issues, such as motion artifacts, and the newest developments and future directions.
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47
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Toniolo M, Figueroa J, Castrejòn-Castrejòn S, Merino JL. Induction of tachycardia confined within a pulmonary vein by electrical cardioversion of atrial fibrillation: Is it proof of reentry? HeartRhythm Case Rep 2015; 1:225-228. [PMID: 28491554 PMCID: PMC5419328 DOI: 10.1016/j.hrcr.2015.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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48
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Galappaththige S, Roth BJ. Electrical Pacing of Cardiac Tissue Including Potassium Inward Rectification. PLoS One 2015; 10:e0127837. [PMID: 26057242 PMCID: PMC4461281 DOI: 10.1371/journal.pone.0127837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/21/2015] [Indexed: 11/19/2022] Open
Abstract
In this study cardiac tissue is stimulated electrically through a small unipolar electrode. Numerical simulations predict that around an electrode are adjacent regions of depolarization and hyperpolarization. Experiments have shown that during pacing of resting cardiac tissue the hyperpolarization is often inhibited. Our goal is to determine if the inward rectifying potassium current (IK1) causes the inhibition of hyperpolarization. Numerical simulations were carried out using the bidomain model with potassium dynamics specified to be inward rectifying. In the simulations, adjacent regions of depolarization and hyperpolarization were observed surrounding the electrode. For cathodal currents the virtual anode produces a hyperpolarization that decreases over time. For long duration pulses the current-voltage curve is non-linear, with very small hyperpolarization compared to depolarization. For short pulses, the hyperpolarization is more prominent. Without the inward potassium rectification, the current voltage curve is linear and the hyperpolarization is evident for both long and short pulses. In conclusion, the inward rectification of the potassium current explains the inhibition of hyperpolarization for long duration stimulus pulses, but not for short duration pulses.
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Affiliation(s)
- Suran Galappaththige
- Department of Physics, Oakland University, Rochester, Michigan, United States of America
| | - Bradley J. Roth
- Department of Physics, Oakland University, Rochester, Michigan, United States of America
- * E-mail:
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49
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Vandersickel N, Kazbanov IV, Defauw A, Pijnappels DA, Panfilov AV. Decreased repolarization reserve increases defibrillation threshold by favoring early afterdepolarizations in an in silico model of human ventricular tissue. Heart Rhythm 2015; 12:1088-96. [PMID: 25623180 DOI: 10.1016/j.hrthm.2015.01.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Nele Vandersickel
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium.
| | - Ivan V Kazbanov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Arne Defauw
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Daniël A Pijnappels
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Alexander V Panfilov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium; Laboratory of Mathematical Modeling in Physiology and Medicine, Ural Federal University, Ekaterinburg, Russia
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50
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Imaging of Ventricular Fibrillation and Defibrillation: The Virtual Electrode Hypothesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:343-65. [PMID: 26238060 DOI: 10.1007/978-3-319-17641-3_14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Ventricular fibrillation is the major underlying cause of sudden cardiac death. Understanding the complex activation patterns that give rise to ventricular fibrillation requires high resolution mapping of localized activation. The use of multi-electrode mapping unraveled re-entrant activation patterns that underlie ventricular fibrillation. However, optical mapping contributed critically to understanding the mechanism of defibrillation, where multi-electrode recordings could not measure activation patterns during and immediately after a shock. In addition, optical mapping visualizes the virtual electrodes that are generated during stimulation and defibrillation pulses, which contributed to the formulation of the virtual electrode hypothesis. The generation of virtual electrode induced phase singularities during defibrillation is arrhythmogenic and may lead to the induction of fibrillation subsequent to defibrillation. Defibrillating with low energy may circumvent this problem. Therefore, the current challenge is to use the knowledge provided by optical mapping to develop a low energy approach of defibrillation, which may lead to more successful defibrillation.
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