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Hussaini S, Mamyraiym Kyzy A, Schröder-Schetelig J, Lädke SL, Venkatesan V, Diaz-Maue L, Quiñonez Uribe RA, Richter C, Biktashev VN, Majumder R, Krinski V, Luther S. Efficient termination of cardiac arrhythmias using optogenetic resonant feedback pacing. CHAOS (WOODBURY, N.Y.) 2024; 34:031103. [PMID: 38526981 DOI: 10.1063/5.0191519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/03/2024] [Indexed: 03/27/2024]
Abstract
Malignant cardiac tachyarrhythmias are associated with complex spatiotemporal excitation of the heart. The termination of these life-threatening arrhythmias requires high-energy electrical shocks that have significant side effects, including tissue damage, excruciating pain, and worsening prognosis. This significant medical need has motivated the search for alternative approaches that mitigate the side effects, based on a comprehensive understanding of the nonlinear dynamics of the heart. Cardiac optogenetics enables the manipulation of cellular function using light, enhancing our understanding of nonlinear cardiac function and control. Here, we investigate the efficacy of optically resonant feedback pacing (ORFP) to terminate ventricular tachyarrhythmias using numerical simulations and experiments in transgenic Langendorff-perfused mouse hearts. We show that ORFP outperforms the termination efficacy of the optical single-pulse (OSP) approach. When using ORFP, the total energy required for arrhythmia termination, i.e., the energy summed over all pulses in the sequence, is 1 mJ. With a success rate of 50%, the energy per pulse is 40 times lower than with OSP with a pulse duration of 10 ms. We demonstrate that even at light intensities below the excitation threshold, ORFP enables the termination of arrhythmias by spatiotemporal modulation of excitability inducing spiral wave drift.
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Affiliation(s)
- S Hussaini
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen 37075, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
| | - A Mamyraiym Kyzy
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
| | - J Schröder-Schetelig
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen 37075, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
| | - S L Lädke
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
| | - V Venkatesan
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
| | - L Diaz-Maue
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
- Research Electronics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
| | - R A Quiñonez Uribe
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
| | - C Richter
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
- WG Cardiovascular Optogenetics, Lab Animal Science Unit, Leibniz Institute for Primate Research, Göttingen 37077, Germany
| | - V N Biktashev
- Department of Mathematics and Statistics, University of Exeter, Exeter EX4 4QF, United Kingdom
| | - R Majumder
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen 37075, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
| | - V Krinski
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
| | - S Luther
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organisation, Göttingen 37077, Germany
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Göttingen 37075, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Lower Saxony, Göttingen 37075, Germany
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2
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Okada JI, Washio T, Sugiura S, Hisada T. Low-energy defibrillation using a base-apex epicardial electrode. Pacing Clin Electrophysiol 2023; 46:1325-1332. [PMID: 37830313 DOI: 10.1111/pace.14832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/17/2023] [Accepted: 09/10/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND Current implantable cardioverter defibrillators (ICDs) require electric conduction with high voltage and high energy, which can impair cardiac function and induce another malignant arrhythmia. As a result, there has been a demand for an ICD that can effectively operate with lower energy to mitigate the risks of a strong electric shock. METHODS A pair of sheet-shaped electrodes covering the heart were analyzed in three configurations (top-bottom, left-right, and front-back) using a heart simulator. We also varied the distance between the two electrodes (clearance) to identify the electrode shape with the lowest defibrillation threshold (DFT). We also investigated the ICD shock waveform, shock direction, and the effect of the backside insulator of the electrode. RESULTS The DFT was high when the clearance was too small and the DFT was high even when the clearance was too large, suggesting that an optimal value clearance. The top-bottom electrodes with optimal clearance showed the lowest DFT when the biphasic shocks set the top electrode to a high potential first and then the bottom electrode was set to a high potential. An interval between a first shock waveform and a second shock waveform should be provided for low-energy defibrillation. Because the insulator prevents unnecessary current flow to the backside, the DFT of the electrodes with insulators is less than those without insulators. CONCLUSION Painless defibrillation using sheet-shaped electrodes on the epicardium is predicated on the basis of results using a heart simulator.
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Affiliation(s)
- Jun-Ichi Okada
- UT-Heart Inc., Setagaya-ku, Tokyo, Japan
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-shi, Chiba, Japan
| | - Takumi Washio
- UT-Heart Inc., Setagaya-ku, Tokyo, Japan
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-shi, Chiba, Japan
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Biasi N, Seghetti P, Mercati M, Tognetti A. A smoothed boundary bidomain model for cardiac simulations in anatomically detailed geometries. PLoS One 2023; 18:e0286577. [PMID: 37294777 PMCID: PMC10256234 DOI: 10.1371/journal.pone.0286577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 05/18/2023] [Indexed: 06/11/2023] Open
Abstract
This manuscript presents a novel finite difference method to solve cardiac bidomain equations in anatomical models of the heart. The proposed method employs a smoothed boundary approach that represents the boundaries between the heart and the surrounding medium as a spatially diffuse interface of finite thickness. The bidomain boundary conditions are implicitly implemented in the smoothed boundary bidomain equations presented in the manuscript without the need of a structured mesh that explicitly tracks the heart-torso boundaries. We reported some significant examples assessing the method's accuracy using nontrivial test geometries and demonstrating the applicability of the method to complex anatomically detailed human cardiac geometries. In particular, we showed that our approach could be employed to simulate cardiac defibrillation in a human left ventricle comprising fiber architecture. The main advantage of the proposed method is the possibility of implementing bidomain boundary conditions directly on voxel structures, which makes it attractive for three dimensional, patient specific simulations based on medical images. Moreover, given the ease of implementation, we believe that the proposed method could provide an interesting and feasible alternative to finite element methods, and could find application in future cardiac research guiding electrotherapy with computational models.
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Affiliation(s)
- Niccolò Biasi
- Information Engineering Department, University of Pisa, Pisa, Italy
| | - Paolo Seghetti
- Health Science Interdisciplinary Center, Scuola Superiore Sant’Anna, Pisa, Italy
- National Research Council, Institute of Clinical Physiology, Pisa, Italy
| | - Matteo Mercati
- Information Engineering Department, University of Pisa, Pisa, Italy
| | - Alessandro Tognetti
- Information Engineering Department, University of Pisa, Pisa, Italy
- Research Centre “E. Piaggio”, University of Pisa, Pisa, Italy
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Buchan S, Kar R, John M, Post A, Razavi M. Electrical Stimulation for Low-Energy Termination of Cardiac Arrhythmias: a Review. Cardiovasc Drugs Ther 2023; 37:323-340. [PMID: 34363570 DOI: 10.1007/s10557-021-07236-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/02/2021] [Indexed: 11/24/2022]
Abstract
Cardiac arrhythmias are a leading cause of morbidity and mortality in the developed world, estimated to be responsible for hundreds of thousands of deaths annually. Our understanding of the electrophysiological mechanisms of such arrhythmias has grown since they were formally characterized in the late nineteenth century, and this has led to the development of numerous devices and therapies that have markedly improved outcomes for patients affected by such conditions. Despite these advancements, the application of a single large shock remains the clinical standard for treating deadly tachyarrhythmias. Such defibrillating shocks are undoubtedly effective in terminating such arrhythmias; however, they are applied without forewarning, contributing to the patient's stress and anxiety; they can be intensely painful; and they can have adverse psychological and physiological effects on patients. In recent years, there has been interest in developing defibrillation protocols that can terminate arrhythmias without crossing the human pain threshold for energy delivery, generally estimated to be between 0.1 and 1 J. In this article, we review existing literature on the development of such low-energy defibrillation methods and their underlying mechanisms, in an attempt to broadly describe the current landscape of these technologies.
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Affiliation(s)
- Skylar Buchan
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX, 77030, USA
| | - Ronit Kar
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX, 77030, USA.,Department of Biomedical Engineering, The University of Texas At Austin, Austin, TX, 78712, USA
| | - Mathews John
- Electrophysiology Clinical Research and Innovations, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX, 77030, USA
| | - Allison Post
- 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. .,Division of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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5
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Das TS, Wilson D. Optimal entrainment for removal of pinned spiral waves. Phys Rev E 2022; 105:064213. [PMID: 35854563 DOI: 10.1103/physreve.105.064213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Cardiac fibrillation is caused by self-sustaining spiral waves that occur in the myocardium, some of which can be pinned to anatomical obstacles, making them more difficult to eliminate. A small electrical stimulation is often sufficient to unpin these spirals but only if it is applied during the vulnerable unpinning window. Even if these unpinning windows can be inferred from data, when multiple pinned spirals exist, their unpinning windows will not generally overlap. Using phase-based reduction techniques, we formulate and solve an optimal control problem to yield a time-varying external voltage gradient that can synchronize a collection of spiral waves that are pinned to a collection of heterogeneous obstacles. Upon synchronization, the unpinning windows overlap so that they can be simultaneously unpinned by applying an external voltage gradient pulse at an appropriate moment. Numerical validation is presented in bidomain model simulations. Results represent a proof-of-concept illustration of the proposed unpinning strategy which explicitly incorporates heterogeneity in the problem formulation and requires no real-time feedback about the system state.
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Affiliation(s)
- Tuhin Subhra Das
- Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Dan Wilson
- Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee 37996, USA
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Kulangareth NV, Magtibay K, Massé S, Krishnakumar Nair, Dorian P, Nanthakumar K, Umapathy K. An In-Silico model for evaluating the directional shock vectors in terminating and modulating rotors. Comput Biol Med 2022; 146:105665. [DOI: 10.1016/j.compbiomed.2022.105665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/03/2022] [Accepted: 05/19/2022] [Indexed: 11/27/2022]
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Mazumder O, Banerjee R, Roy D, Mukherjee A, Ghose A, Khandelwal S, Sinha A. Computational Model for Therapy Optimization of Wearable Cardioverter Defibrillator: Shockable Rhythm Detection and Optimal Electrotherapy. Front Physiol 2021; 12:787180. [PMID: 34955894 PMCID: PMC8703044 DOI: 10.3389/fphys.2021.787180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/08/2021] [Indexed: 11/15/2022] Open
Abstract
Wearable cardioverter defibrillator (WCD) is a life saving, wearable, noninvasive therapeutic device that prevents fatal ventricular arrhythmic propagation that leads to sudden cardiac death (SCD). WCD are frequently prescribed to patients deemed to be at high arrhythmic risk but the underlying pathology is potentially reversible or to those who are awaiting an implantable cardioverter-defibrillator. WCD is programmed to detect appropriate arrhythmic events and generate high energy shock capable of depolarizing the myocardium and thus re-initiating the sinus rhythm. WCD guidelines dictate very high reliability and accuracy to deliver timely and optimal therapy. Computational model-based process validation can verify device performance and benchmark the device setting to suit personalized requirements. In this article, we present a computational pipeline for WCD validation, both in terms of shock classification and shock optimization. For classification, we propose a convolutional neural network-"Long Short Term Memory network (LSTM) full form" (Convolutional neural network- Long short term memory network (CNN-LSTM)) based deep neural architecture for classifying shockable rhythms like Ventricular Fibrillation (VF), Ventricular Tachycardia (VT) vs. other kinds of non-shockable rhythms. The proposed architecture has been evaluated on two open access ECG databases and the classification accuracy achieved is in adherence to American Heart Association standards for WCD. The computational model developed to study optimal electrotherapy response is an in-silico cardiac model integrating cardiac hemodynamics functionality and a 3D volume conductor model encompassing biophysical simulation to compute the effect of shock voltage on myocardial potential distribution. Defibrillation efficacy is simulated for different shocking electrode configurations to assess the best defibrillator outcome with minimal myocardial damage. While the biophysical simulation provides the field distribution through Finite Element Modeling during defibrillation, the hemodynamic module captures the changes in left ventricle functionality during an arrhythmic event. The developed computational model, apart from acting as a device validation test-bed, can also be used for the design and development of personalized WCD vests depending on subject-specific anatomy and pathology.
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8
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Qian S, Connolly A, Mendonca-Costa C, Campos F, Williams SE, Whitaker J, Rinaldi CA, Bishop MJ. An in-silico assessment of efficacy of two novel intra-cardiac electrode configurations versus traditional anti-tachycardia pacing therapy for terminating sustained ventricular tachycardia. Comput Biol Med 2021; 139:104987. [PMID: 34741904 PMCID: PMC8669079 DOI: 10.1016/j.compbiomed.2021.104987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/24/2021] [Accepted: 10/24/2021] [Indexed: 11/06/2022]
Abstract
The implanted cardioverter defibrillator (ICD) is an effective direct therapy for the treatment of cardiac arrhythmias, including ventricular tachycardia (VT). Anti-tachycardia pacing (ATP) is often applied by the ICD as the first mode of therapy, but is often found to be ineffective, particularly for fast VTs. In such cases, strong, painful and damaging backup defibrillation shocks are applied by the device. Here, we propose two novel electrode configurations: "bipolar" and "transmural" which both combine the concept of targeted shock delivery with the advantage of reduced energy required for VT termination. We perform an in silico study to evaluate the efficacy of VT termination by applying one single (low-energy) monophasic shock from each novel configuration, comparing with conventional ATP therapy. Both bipolar and transmural configurations are able to achieve a higher efficacy (93% and 85%) than ATP (45%), with energy delivered similar to and two orders of magnitudes smaller than conventional ICD defibrillation shocks, respectively. Specifically, the transmural configuration (which applies the shock vector directly across the scar substrate sustaining the VT) is most efficient, requiring typically less than 1 J shock energy to achieve a high efficacy. The efficacy of both bipolar and transmural configurations are higher when applied to slow VTs (100% and 97%) compared to fast VTs (57% and 29%). Both novel electrode configurations introduced are able to improve electrotherapy efficacy while reducing the overall number of required therapies and need for strong backup shocks.
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Affiliation(s)
- Shuang Qian
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom.
| | - Adam Connolly
- Invicro, Burlington Danes Building, Du Cane Rd, London, W12 0N, United Kingdom
| | - Caroline Mendonca-Costa
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom
| | - Fernando Campos
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom
| | - Steven E Williams
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom
| | - John Whitaker
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom; Department of Cardiology, Guy's and St Thomas' Hospital, London, SE1 7EH, United Kingdom
| | - Christopher A Rinaldi
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom; Department of Cardiology, Guy's and St Thomas' Hospital, London, SE1 7EH, United Kingdom
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, 4th Floor, Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Road, London, SE1 7EH, United Kingdom
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Kulangareth NV, Umapathy K. Effect of Shock Vector Orientation in Modulating and Terminating Rotors - a Simulation Study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:5488-5491. [PMID: 34892367 DOI: 10.1109/embc46164.2021.9630733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The main treatment option for Ventricular Fibrillation (VF), especially in out-of-hospital cardiac arrests (OHCA) is defibrillation. Typically, the survival-to-discharge rates are very poor for OHCA. Existing studies have shown that rotors may be the sources of arrhythmia and ablating them could modulate or terminate VF. However, tracking rotors and ablating them is not a feasible solution in a OHCA scenario. Hence, if the sources (or rotors) can be regionally localized non-invasively and this information can be used to direct the orientation of the shock vectors, it may aid the termination of rotors and defibrillation success. In this work, using computational modeling, we present our initial results on testing the effect of shock vector orientation on modulating (or) terminating rotors. A combination of Sovilj's and Aliev Panfilov's monodomain cardiac models were used in inducing rotors and testing the effect of shock vector magnitude and direction. Based on our simulation results on an average with four experimental trials, a shock vector directed in the perpendicular direction along the axis of the rotor terminated the rotor with 16% lesser magnitude than parallel direction and 38% lesser magnitude than in oblique direction.Clinical Relevance- A rotor localization dependent defibrillation strategy may aid the defibrillation protocol procedures to improve the survival rates. Based on the four experimental trials, the results indicate shock vectors oriented perpendicular to the axis of the rotors were efficient in modulating or terminating rotors with lower magnitude than other directions.
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10
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Sehgal S, Foulkes AJ. Numerical analysis of subcritical Hopf bifurcations in the two-dimensional FitzHugh-Nagumo model. Phys Rev E 2020; 102:012212. [PMID: 32795073 DOI: 10.1103/physreve.102.012212] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/24/2020] [Indexed: 11/07/2022]
Abstract
It had been shown that the transition from a rigidly rotating spiral wave to a meandering spiral wave is via a Hopf bifurcation. Many studies have shown that these bifurcations are supercritical, but, by using simulations in a comoving frame of reference, we present numerical results which show that subcritical bifurcations are also present within FitzHugh-Nagumo. We show that a hysteresis region is present at the boundary of the rigidly rotating spiral waves and the meandering spiral waves for a particular set of parameters, a feature of FitzHugh-Nagumo that has previously not been reported. Furthermore, we present a evidence that this bifurcation is highly sensitive to initial conditions, and it is possible to convert one solution in the hysteresis loop to the other.
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Affiliation(s)
- S Sehgal
- School of Mathematics, Computer Science and Engineering, Liverpool Hope University, Liverpool, United Kingdom
| | - A J Foulkes
- School of Mathematics, Computer Science and Engineering, Liverpool Hope University, Liverpool, United Kingdom
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11
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Holden AV, Begg GA, Bounford K, Stegemann B, Tayebjee MH. Phase Entrainment of Induced Ventricular Fibrillation: A Human Feasibility and Proof of Concept Study. J Atr Fibrillation 2019; 12:2217. [PMID: 32435345 DOI: 10.4022/jafib.2217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/19/2019] [Accepted: 09/21/2019] [Indexed: 11/10/2022]
Abstract
Cardioversion and defibrillation by a single high energy shock applied by myocardial or body surface electrodes is painful, causes long term tissue damage, and is associated with worsening long term outcomes, but is almost always required for treatment of ventricular fibrillation . As a initial step towards developing methods that can terminate ventricular arrhythmias painlessly, we aim to determine if pacing stimuli at a rate of 5/s applied via an implantable cardiac defibrillator (ICD) can modify human ventricular fibrillation. In 8 patients undergoing defibrillation testing of a new/exchanged intracardiac defibrillator, five seconds of pacing at five stimuli per second was applied during the 10-20 seconds of induced ventricular fibrillation before the defibrillation shock was automatically applied, and the cardiac electrograms recorded and analyzed. The high frequency pacing did not entrain the ventricular fibrillation, but altered the dominant frequency in all 8 patients, and modulated the phase computed via the Hilbert Transform, in four of the patients. In this pilot study we demonstrate that high frequency pacing applied via ICD electrodes during VF can alter the dominant frequency and modulate the probability density of the phase of the electrogram of the ventricular fibrillation.
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Affiliation(s)
- Arun V Holden
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT; UK
| | - Gordon A Begg
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
| | - Katrina Bounford
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
| | - Berthold Stegemann
- Medtronic Plc, Bakken Research Center, Endepolsdomein 5, 6229 GW Maastricht, The Netherlands
| | - Muzahir H Tayebjee
- West Yorkshire Arrhythmia Service, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX, UK
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Bowler LA, Gavaghan DJ, Mirams GR, Whiteley JP. Representation of Multiple Cellular Phenotypes Within Tissue-Level Simulations of Cardiac Electrophysiology. Bull Math Biol 2019; 81:7-38. [PMID: 30291590 PMCID: PMC6320359 DOI: 10.1007/s11538-018-0516-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 07/31/2018] [Indexed: 12/12/2022]
Abstract
Distinct electrophysiological phenotypes are exhibited by biological cells that have differentiated into particular cell types. The usual approach when simulating the cardiac electrophysiology of tissue that includes different cell types is to model the different cell types as occupying spatially distinct yet coupled regions. Instead, we model the electrophysiology of well-mixed cells by using homogenisation to derive an extension to the commonly used monodomain or bidomain equations. These new equations permit spatial variations in the distribution of the different subtypes of cells and will reduce the computational demands of solving the governing equations. We validate the homogenisation computationally, and then use the new model to explain some experimental observations from stem cell-derived cardiomyocyte monolayers.
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Affiliation(s)
- Louise A Bowler
- Department of Computer Science, University of Oxford, Oxford, UK
| | - David J Gavaghan
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Gary R Mirams
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
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Sachetto Oliveira R, Martins Rocha B, Burgarelli D, Meira W, Constantinides C, Weber Dos Santos R. Performance evaluation of GPU parallelization, space-time adaptive algorithms, and their combination for simulating cardiac electrophysiology. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2913. [PMID: 28636811 DOI: 10.1002/cnm.2913] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 06/09/2017] [Accepted: 06/16/2017] [Indexed: 05/23/2023]
Abstract
The use of computer models as a tool for the study and understanding of the complex phenomena of cardiac electrophysiology has attained increased importance nowadays. At the same time, the increased complexity of the biophysical processes translates into complex computational and mathematical models. To speed up cardiac simulations and to allow more precise and realistic uses, 2 different techniques have been traditionally exploited: parallel computing and sophisticated numerical methods. In this work, we combine a modern parallel computing technique based on multicore and graphics processing units (GPUs) and a sophisticated numerical method based on a new space-time adaptive algorithm. We evaluate each technique alone and in different combinations: multicore and GPU, multicore and GPU and space adaptivity, multicore and GPU and space adaptivity and time adaptivity. All the techniques and combinations were evaluated under different scenarios: 3D simulations on slabs, 3D simulations on a ventricular mouse mesh, ie, complex geometry, sinus-rhythm, and arrhythmic conditions. Our results suggest that multicore and GPU accelerate the simulations by an approximate factor of 33×, whereas the speedups attained by the space-time adaptive algorithms were approximately 48. Nevertheless, by combining all the techniques, we obtained speedups that ranged between 165 and 498. The tested methods were able to reduce the execution time of a simulation by more than 498× for a complex cellular model in a slab geometry and by 165× in a realistic heart geometry simulating spiral waves. The proposed methods will allow faster and more realistic simulations in a feasible time with no significant loss of accuracy.
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Affiliation(s)
- Rafael Sachetto Oliveira
- Departamento de Ciência da Computação, Universidade Federal de São João de Rei, São João del-rei MG, Brazil
| | - Bernardo Martins Rocha
- Departamento de Ciência da Computação e Programa em Modelagem Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil
| | - Denise Burgarelli
- Departamento de Matemática, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Wagner Meira
- Departamento de Ciência da Computação, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Rodrigo Weber Dos Santos
- Departamento de Ciência da Computação e Programa em Modelagem Computacional, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil
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A Computer Simulation Study of Anatomy Induced Drift of Spiral Waves in the Human Atrium. BIOMED RESEARCH INTERNATIONAL 2015; 2015:731386. [PMID: 26587545 PMCID: PMC4637448 DOI: 10.1155/2015/731386] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/09/2014] [Indexed: 12/03/2022]
Abstract
The interaction of spiral waves of excitation with atrial anatomy remains unclear. This simulation study isolates the role of atrial anatomical structures on spiral wave spontaneous drift in the human atrium. We implemented realistic and idealised 3D human atria models to investigate the functional impact of anatomical structures on the long-term (∼40 s) behaviour of spiral waves. The drift of a spiral wave was quantified by tracing its tip trajectory, which was correlated to atrial anatomical features. The interaction of spiral waves with the following idealised geometries was investigated: (a) a wedge-like structure with a continuously varying atrial wall thickness; (b) a ridge-like structure with a sudden change in atrial wall thickness; (c) multiple bridge-like structures consisting of a bridge connected to the atrial wall. Spiral waves drifted from thicker to thinner regions and along ridge-like structures. Breakthrough patterns caused by pectinate muscles (PM) bridges were also observed, albeit infrequently. Apparent anchoring close to PM-atrial wall junctions was observed. These observations were similar in both the realistic and the idealised models. We conclude that spatially altering atrial wall thickness is a significant cause of drift of spiral waves. PM bridges cause breakthrough patterns and induce transient anchoring of spiral waves.
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15
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Jin L, Wang J, Song B, Wu X, Fang Z. Low-energy defibrillation with multi-electrodes stimulation: A simulation study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2015:5688-5691. [PMID: 26737583 DOI: 10.1109/embc.2015.7319683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The objective of this study is to explore the possible ways to reduce defibrillation energy and further reveal the mechanism of electric defibrillation. A bidomain simulation study was performed on a rabbit whole-ventricle electrophysiological model and the feasibility of the defibrillation strategy with multi-electrodes stimulation was verified. Simulation results indicate that the new approach is effective in low-energy defibrillation.
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16
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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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17
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Konakanchi D, de Jongh Curry AL, Dokos S. Effects of macroscopic heterogeneity on propagation in a computationally inexpensive 2D model of the heart. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2014; 2014:4320-4323. [PMID: 25570948 DOI: 10.1109/embc.2014.6944580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have developed a computationally inexpensive, two-dimensional, bidomain model of the heart to demonstrate the effect of tissue heterogeneity on propagation of cardiac impulses generated by the sino-atrial node (SAN). The geometry consists of a thin sheet of cardiac tissue with designated areas that represent the SAN and atria. The SAN auto-generates continuous impulses that result in waves of normal propagation throughout the tissue. On the introduction of heterogeneous patches with low tissue conductivities, the rhythm of the waveform becomes irregular. The study suggests that simplified and computationally inexpensive models can be insightful tools to better understand the mechanisms that cause atrial fibrillation (AF) and hence more effective treatment methods.
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18
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Dierckx H, Verschelde H. Effective dynamics of twisted and curved scroll waves using virtual filaments. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062907. [PMID: 24483531 DOI: 10.1103/physreve.88.062907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Indexed: 06/03/2023]
Abstract
Scroll waves are three-dimensional excitation patterns that rotate around a central filament curve; they occur in many physical, biological, and chemical systems. We explicitly derive the equations of motion for scroll wave filaments in reaction-diffusion systems with isotropic diffusion up to third order in the filament's twist and curvature. The net drift components define at every instance of time a virtual filament which lies close to the instantaneous filament. Importantly, virtual filaments obey simpler, time-independent laws of motion which we analytically derive here and illustrate with numerical examples. Stability analysis of scroll waves is performed using virtual filaments, showing that filament curvature and twist add as quadratic terms to the nominal filament tension. Applications to oscillating chemical reactions and cardiac tissue are discussed.
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Affiliation(s)
- Hans Dierckx
- Department of Mathematical Physics and Astronomy, Ghent University, Krijgslaan 281 S9 WE05, 9000 Ghent, Belgium
| | - Henri Verschelde
- Department of Mathematical Physics and Astronomy, Ghent University, Krijgslaan 281 S9 WE05, 9000 Ghent, Belgium
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19
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Lenk C, Einax M, Maass P. Irregular excitation patterns in reaction-diffusion systems due to perturbation by secondary pacemakers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:042904. [PMID: 23679486 DOI: 10.1103/physreve.87.042904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Indexed: 06/02/2023]
Abstract
Spatiotemporal excitation patterns in the FitzHugh-Nagumo model are studied, which result from the disturbance of a primary pacemaker by a secondary pacemaker. The primary and secondary pacemakers generate regular waves with frequencies f(pace) and f(pert), respectively. The pacemakers are spatially separated, but waves emanating from them encounter each other via a small bridge. This leads to three different types I-III of irregular excitation patterns in disjunct domains of the f(pace)-f(pert) plane. Types I and II are caused by detachments of waves coming from the two pacemakers at corners of the bridge. Type III irregularities are confined to a boundary region of the system and originate from a partial penetration of the primary waves into a space, where circular wave fronts from the secondary pacemaker prevail. For this type, local frequencies can significantly exceed f(pace) and f(pert). The degree of irregularity found for the three different types is quantified by the entropy of the local frequency distribution and an order parameter for phase coherence.
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Affiliation(s)
- Claudia Lenk
- Institut für Chemie und Biotechnik, Technische Universität Ilmenau, 98684 Ilmenau, Germany.
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20
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Yamazaki M, Honjo H, Ashihara T, Harada M, Sakuma I, Nakazawa K, Trayanova N, Horie M, Kalifa J, Jalife J, Kamiya K, Kodama I. Regional cooling facilitates termination of spiral-wave reentry through unpinning of rotors in rabbit hearts. Heart Rhythm 2011; 9:107-14. [PMID: 21839044 DOI: 10.1016/j.hrthm.2011.08.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
BACKGROUND Moderate global cooling of myocardial tissue was shown to destabilize 2-dimensional (2-D) reentry and facilitate its termination. OBJECTIVE This study sought to test the hypothesis that regional cooling destabilizes rotors and facilitates termination of spontaneous and DC shock-induced subepicardial reentry in isolated, endocardially ablated rabbit hearts. METHODS Fluorescent action potential signals were recorded from 2-D subepicardial ventricular myocardium of Langendorff-perfused rabbit hearts. Regional cooling (by 5.9°C ± 1.3°C) was applied to the left ventricular anterior wall using a transparent cooling device (10 mm in diameter). RESULTS Regional cooling during constant stimulation (2.5 Hz) prolonged the action potential duration (by 36% ± 9%) and slightly reduced conduction velocity (by 4% ± 4%) in the cooled region. Ventricular tachycardias (VTs) induced during regional cooling terminated earlier than those without cooling (control): VTs lasting >30 seconds were reduced from 17 of 39 to 1 of 61. When regional cooling was applied during sustained VTs (>120 seconds), 16 of 33 (48%) sustained VTs self-terminated in 12.5 ± 5.1 seconds. VT termination was the result of rotor destabilization, which was characterized by unpinning, drift toward the periphery of the cooled region, and subsequent collision with boundaries. The DC shock intensity required for cardioversion of the sustained VTs decreased significantly by regional cooling (22.8 ± 4.1 V, n = 16, vs 40.5 ± 17.6 V, n = 21). The major mode of reentry termination by DC shocks was phase resetting in the absence of cooling, whereas it was unpinning in the presence of cooling. CONCLUSION Regional cooling facilitates termination of 2-D reentry through unpinning of rotors.
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Affiliation(s)
- Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Chikusa-ku, Nagoya, Japan
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Bishop MJ, Plank G, Burton RAB, Schneider JE, Gavaghan DJ, Grau V, Kohl P. Development of an anatomically detailed MRI-derived rabbit ventricular model and assessment of its impact on simulations of electrophysiological function. Am J Physiol Heart Circ Physiol 2009; 298:H699-718. [PMID: 19933417 PMCID: PMC2822578 DOI: 10.1152/ajpheart.00606.2009] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent advances in magnetic resonance (MR) imaging technology have unveiled a wealth of information regarding cardiac histoanatomical complexity. However, methods to faithfully translate this level of fine-scale structural detail into computational whole ventricular models are still in their infancy, and, thus, the relevance of this additional complexity for simulations of cardiac function has yet to be elucidated. Here, we describe the development of a highly detailed finite-element computational model (resolution: approximately 125 microm) of rabbit ventricles constructed from high-resolution MR data (raw data resolution: 43 x 43 x 36 microm), including the processes of segmentation (using a combination of level-set approaches), identification of relevant anatomical features, mesh generation, and myocyte orientation representation (using a rule-based approach). Full access is provided to the completed model and MR data. Simulation results were compared with those from a simplified model built from the same images but excluding finer anatomical features (vessels/endocardial structures). Initial simulations showed that the presence of trabeculations can provide shortcut paths for excitation, causing regional differences in activation after pacing between models. Endocardial structures gave rise to small-scale virtual electrodes upon the application of external field stimulation, which appeared to protect parts of the endocardium in the complex model from strong polarizations, whereas intramural virtual electrodes caused by blood vessels and extracellular cleft spaces appeared to reduce polarization of the epicardium. Postshock, these differences resulted in the genesis of new excitation wavefronts that were not observed in more simplified models. Furthermore, global differences in the stimulus recovery rates of apex/base regions were observed, causing differences in the ensuing arrhythmogenic episodes. In conclusion, structurally simplified models are well suited for a large range of cardiac modeling applications. However, important differences are seen when behavior at microscales is relevant, particularly when examining the effects of external electrical stimulation on tissue electrophysiology and arrhythmia induction. This highlights the utility of histoanatomically detailed models for investigations of cardiac function, in particular for future patient-specific modeling.
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Affiliation(s)
- Martin J Bishop
- University of Oxford Computing Laboratory, Parks Road, Oxford OX1 3QD, UK.
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