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Myklebust L, Monopoli G, Balaban G, Aabel EW, Ribe M, Castrini AI, Hasselberg NE, Bugge C, Five C, Haugaa K, Maleckar MM, Arevalo H. Stretch of the papillary insertion triggers reentrant arrhythmia: an in silico patient study. Front Physiol 2024; 15:1447938. [PMID: 39224207 PMCID: PMC11366717 DOI: 10.3389/fphys.2024.1447938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Accepted: 08/01/2024] [Indexed: 09/04/2024] Open
Abstract
Background The electrophysiological mechanism connecting mitral valve prolapse (MVP), premature ventricular complexes and life-threatening ventricular arrhythmia is unknown. A common hypothesis is that stretch activated channels (SACs) play a significant role. SACs can trigger depolarizations or shorten repolarization times in response to myocardial stretch. Through these mechanisms, pathological traction of the papillary muscle (PM), as has been observed in patients with MVP, may induce irregular electrical activity and result in reentrant arrhythmia. Methods Based on a patient with MVP and mitral annulus disjunction, we modeled the effect of excessive PM traction in a detailed medical image-derived ventricular model by activating SACs in the PM insertion region. By systematically varying the onset of SAC activation following sinus pacing, we identified vulnerability windows for reentry with 1 ms resolution. We explored how reentry was affected by the SAC reversal potential ( E SAC ) and the size of the region with simulated stretch (SAC region). Finally, the effect of global or focal fibrosis, modeled as reduction in tissue conductivity or mesh splitting (fibrotic microstructure), was investigated. Results In models with healthy tissue or fibrosis modeled solely as CV slowing, we observed two vulnerable periods of reentry: ForE SAC of -10 and -30 mV, SAC activated during the T-wave could cause depolarization of the SAC region which lead to reentry. ForE SAC of -40 and -70 mV, SAC activated during the QRS complex could result in early repolarization of the SAC region and subsequent reentry. In models with fibrotic microstructure in the SAC region, we observed micro-reentries and a larger variability in which times of SAC activation triggered reentry. In these models, 86% of reentries were triggered during the QRS complex or T-wave. We only observed reentry for sufficiently large SAC regions ( > = 8 mm radius in models with healthy tissue). Conclusion Stretch of the PM insertion region following sinus activation may initiate ventricular reentry in patients with MVP, with or without fibrosis. Depending on the SAC reversal potential and timing of stretch, reentry may be triggered by ectopy due to SAC-induced depolarizations or by early repolarization within the SAC region.
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Affiliation(s)
- Lena Myklebust
- Computational Physiology Department, Simula Research Laboratory, Oslo, Norway
| | - Giulia Monopoli
- Computational Physiology Department, Simula Research Laboratory, Oslo, Norway
| | - Gabriel Balaban
- School of Economics Innovation and Technology, Kristiania University College, Oslo, Norway
| | - Eivind Westrum Aabel
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Margareth Ribe
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Anna Isotta Castrini
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Nina Eide Hasselberg
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Cecilie Bugge
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Christian Five
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Kristina Haugaa
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Mary M. Maleckar
- Computational Physiology Department, Simula Research Laboratory, Oslo, Norway
- ProCardio Center for Innovation, Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Hermenegild Arevalo
- Computational Physiology Department, Simula Research Laboratory, Oslo, Norway
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Trayanova NA, Lyon A, Shade J, Heijman J. Computational modeling of cardiac electrophysiology and arrhythmogenesis: toward clinical translation. Physiol Rev 2024; 104:1265-1333. [PMID: 38153307 PMCID: PMC11381036 DOI: 10.1152/physrev.00017.2023] [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: 04/05/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 12/29/2023] Open
Abstract
The complexity of cardiac electrophysiology, involving dynamic changes in numerous components across multiple spatial (from ion channel to organ) and temporal (from milliseconds to days) scales, makes an intuitive or empirical analysis of cardiac arrhythmogenesis challenging. Multiscale mechanistic computational models of cardiac electrophysiology provide precise control over individual parameters, and their reproducibility enables a thorough assessment of arrhythmia mechanisms. This review provides a comprehensive analysis of models of cardiac electrophysiology and arrhythmias, from the single cell to the organ level, and how they can be leveraged to better understand rhythm disorders in cardiac disease and to improve heart patient care. Key issues related to model development based on experimental data are discussed, and major families of human cardiomyocyte models and their applications are highlighted. An overview of organ-level computational modeling of cardiac electrophysiology and its clinical applications in personalized arrhythmia risk assessment and patient-specific therapy of atrial and ventricular arrhythmias is provided. The advancements presented here highlight how patient-specific computational models of the heart reconstructed from patient data have achieved success in predicting risk of sudden cardiac death and guiding optimal treatments of heart rhythm disorders. Finally, an outlook toward potential future advances, including the combination of mechanistic modeling and machine learning/artificial intelligence, is provided. As the field of cardiology is embarking on a journey toward precision medicine, personalized modeling of the heart is expected to become a key technology to guide pharmaceutical therapy, deployment of devices, and surgical interventions.
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Affiliation(s)
- Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland, United States
| | - Aurore Lyon
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Julie Shade
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland, United States
| | - Jordi Heijman
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
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An Investigation of Left Ventricular Valve Disorders and the Mechano-Electric Feedback Using a Synergistic Lumped Parameter Cardiovascular Numerical Model. Bioengineering (Basel) 2022; 9:bioengineering9090454. [PMID: 36135000 PMCID: PMC9495401 DOI: 10.3390/bioengineering9090454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 08/17/2022] [Accepted: 09/05/2022] [Indexed: 11/17/2022] Open
Abstract
Cardiac diseases and failure make up one of largest contributions to global mortality and significantly detriment the quality of life for millions of others. Disorders in the valves of the left ventricle are a prominent example of heart disease, with prolapse, regurgitation, and stenoses—the three main valve disorders. It is widely known that mitral valve prolapse increases the susceptibility to cardiac arrhythmia. Here, we investigate stenoses and regurgitation of the mitral and aortic valves in the left ventricle using a synergistic low-order numerical model. The model synergy derives from the incorporation of the mechanical, chemical, and electrical elements. As an alternative framework to the time-varying elastance (TVE) method, it allows feedback mechanisms at work in the heart to be considered. The TVE model imposes the ventricular pressure–volume relationship using a periodic function rather than calculating it consistently. Using our synergistic approach, the effects of valve disorders on the mechano-electric-feedback (MEF) are investigated. The MEF is the influence of cellular mechanics on the electrical activity, and significantly contributes to the generation of arrhythmia. We further investigate stenoses and regurgitation of the mitral and aortic valves and their relationship with the MEF and generation of arrhythmia. Mitral valve stenosis is found to increase the sensitivity to arrhythmia-stimulating systolic stretch, and reduces the sensitivity to diastolic stretch. Aortic valve stenosis does not change the sensitivity to arrhythmia-stimulating stretch, and regurgitation reduces it. A key result is found when valve regurgitation is accompanied by diastolic stretch. In the presence of MEF disorder, ectopic beats become far more frequent when accompanied by valve regurgitation. Therefore, arrhythmia resulting from a disorder in the MEF will be more severe when valve regurgitation is present.
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Pearce N, Kim EJ. Modelling the cardiac response to a mechanical stimulation using a low-order model of the heart. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:4871-4893. [PMID: 34198470 DOI: 10.3934/mbe.2021248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heart diseases are one of the leading causes of death worldwide, and a dysfunction of the cardiac electrical mechanisms is responsible for a significant portion of these deaths. One of these mechanisms, the mechano-electric feedback (MEF), is the electrical response of the heart to local mechanical changes in the environment. This electrical response, in turn, leads to macroscopic changes in heart function. In this paper, we demonstrate that the MEF plays a crucial role in mechanical generation and recovery from arrhythmia which has been observed in experimental studies. To this end, we investigate the cardiac response to a mechanical stimulation using a minimal, multiscale model of the heart which couples the organ level dynamics (left ventricular pressure and volume) and contractile dynamics. By including a mechanical stimulation into the model as a (short, sudden) impulse in the muscle microscale stress, we investigate how the timing, amplitude and duration of the impulse affect the cardiac cycle. In particular, when introduced in the diastolic period of the cardiac cycle, the pulse rate can be stabilised, and ectopic beats and bifurcation can be eliminated, either temporarily or permanently. The stimulation amplitude is a key indicator to this response. We find an optimal value of the impulse amplitude above or below which the impulse maximises the stabilisation. As a result a dysfunction of the MEF can be helped using a mechanical stimulation, by allowing the heart to recover its pumping power. On the other hand, when the mechanical stimulation is introduced towards the end of systole, arrhythmia can be generated.
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Affiliation(s)
- Nicholas Pearce
- Fluid and Complex Systems Research Centre, Coventry University, Coventry, CV1 5FB, UK
| | - Eun-Jin Kim
- Fluid and Complex Systems Research Centre, Coventry University, Coventry, CV1 5FB, UK
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Hazim A, Belhamadia Y, Dubljevic S. A Simulation Study of the Role of Mechanical Stretch in Arrhythmogenesis during Cardiac Alternans. Biophys J 2020; 120:109-121. [PMID: 33248131 PMCID: PMC7820729 DOI: 10.1016/j.bpj.2020.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 11/03/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022] Open
Abstract
The deformation of the heart tissue due to the contraction can modulate the excitation, a phenomenon referred to as mechanoelectrical feedback (MEF), via stretch-activated channels. The effects of MEF on the electrophysiology at high pacing rates are shown to be proarrhythmic in general. However, more studies need to be done to elucidate the underlying mechanism. In this work, we investigate the effects of MEF on cardiac alternans, which is an alternation in the width of the action potential that typically occurs when the heart is paced at high rates, using a biophysically detailed electromechanical model of cardiac tissue. We observe that the transition from spatially concordant alternans to spatially discordant alternans, which is more arrhythmogenic than concordant alternans, may occur in the presence of MEF and when its strength is sufficiently large. We show that this transition is due to the increase of the dispersion of conduction velocity. In addition, our results also show that the MEF effects, depending on the stretch-activated channels’ conductances and reversal potentials, can result in blocking action potential propagation.
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Affiliation(s)
- Azzam Hazim
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Youssef Belhamadia
- Department of Mathematics and Statistics, American University of Sharjah, Sharjah, United Arab Emirates
| | - Stevan Dubljevic
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada.
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Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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7
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Izu LT, Kohl P, Boyden PA, Miura M, Banyasz T, Chiamvimonvat N, Trayanova N, Bers DM, Chen-Izu Y. Mechano-electric and mechano-chemo-transduction in cardiomyocytes. J Physiol 2020; 598:1285-1305. [PMID: 31789427 PMCID: PMC7127983 DOI: 10.1113/jp276494] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/21/2019] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction (E-C) coupling is influenced by (at least) three dynamic systems that couple and feedback to one another (see Abstract Figure). Here we review the mechanical effects on cardiomyocytes that include mechano-electro-transduction (commonly referred to as mechano-electric coupling, MEC) and mechano-chemo-transduction (MCT) mechanisms at cell and molecular levels which couple to Ca2+ -electro and E-C coupling reviewed elsewhere. These feedback loops from muscle contraction and mechano-transduction to the Ca2+ homeodynamics and to the electrical excitation are essential for understanding the E-C coupling dynamic system and arrhythmogenesis in mechanically loaded hearts. This white paper comprises two parts, each reflecting key aspects from the 2018 UC Davis symposium: MEC (how mechanical load influences electrical dynamics) and MCT (how mechanical load alters cell signalling and Ca2+ dynamics). Of course, such separation is artificial since Ca2+ dynamics profoundly affect ion channels and electrogenic transporters and vice versa. In time, these dynamic systems and their interactions must become fully integrated, and that should be a goal for a comprehensive understanding of how mechanical load influences cell signalling, Ca2+ homeodynamics and electrical dynamics. In this white paper we emphasize current understanding, consensus, controversies and the pressing issues for future investigations. Space constraints make it impossible to cover all relevant articles in the field, so we will focus on the topics discussed at the symposium.
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Affiliation(s)
- Leighton T. Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre, and Faculty of Medicine, University of Freiburg, D-79110, Germany
| | | | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
| | - Natalia Trayanova
- Department of Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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8
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Wilson SJ, Spratt JC, Hill J, Spence MS, Cosgrove C, Jones J, Strange JW, Halperin H, Walsh SJ, Hanratty CG. Incidence of “shocktopics” and asynchronous cardiac pacing in patients undergoing coronary intravascular lithotripsy. EUROINTERVENTION 2020; 15:1429-1435. [DOI: 10.4244/eij-d-19-00484] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Morotti S, Grandi E. Quantitative systems models illuminate arrhythmia mechanisms in heart failure: Role of the Na + -Ca 2+ -Ca 2+ /calmodulin-dependent protein kinase II-reactive oxygen species feedback. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2018; 11:e1434. [PMID: 30015404 DOI: 10.1002/wsbm.1434] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/29/2018] [Accepted: 06/16/2018] [Indexed: 12/22/2022]
Abstract
Quantitative systems modeling aims to integrate knowledge in different research areas with models describing biological mechanisms and dynamics to gain a better understanding of complex clinical syndromes. Heart failure (HF) is a chronic complex cardiac disease that results from structural or functional disorders impairing the ability of the ventricle to fill with or eject blood. Highly interactive and dynamic changes in mechanical, structural, neurohumoral, metabolic, and electrophysiological properties collectively predispose the failing heart to cardiac arrhythmias, which are responsible for about a half of HF deaths. Multiscale cardiac modeling and simulation integrate structural and functional data from HF experimental models and patients to improve our mechanistic understanding of this complex arrhythmia syndrome. In particular, they allow investigating how disease-induced remodeling alters the coupling of electrophysiology, Ca2+ and Na+ handling, contraction, and energetics that lead to rhythm derangements. The Ca2+ /calmodulin-dependent protein kinase II, which expression and activity are enhanced in HF, emerges as a critical hub that modulates the feedbacks between these various subsystems and promotes arrhythmogenesis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Models of Systems Properties and Processes > Mechanistic Models Models of Systems Properties and Processes > Cellular Models Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California
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Amar A, Zlochiver S, Barnea O. Mechano-electric feedback effects in a three-dimensional (3D) model of the contracting cardiac ventricle. PLoS One 2018; 13:e0191238. [PMID: 29342222 PMCID: PMC5771591 DOI: 10.1371/journal.pone.0191238] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/30/2017] [Indexed: 11/22/2022] Open
Abstract
Mechano-electric feedback affects the electrophysiological and mechanical function of the heart and the cellular, tissue, and organ properties. To determine the main factors that contribute to this effect, this study investigated the changes in the action potential characteristics of the ventricle during contraction. A model of stretch-activated channels was incorporated into a three-dimensional multiscale model of the contracting ventricle to assess the effect of different preload lengths on the electrophysiological behavior. The model describes the initiation and propagation of the electrical impulse, as well as the passive (stretch) and active (contraction) changes in the cardiac mechanics. Simulations were performed to quantify the relationship between the cellular activation and recovery patterns as well as the action potential durations at different preload lengths in normal and heart failure pathological conditions. The simulation results showed that heart failure significantly affected the excitation propagation parameters compared to normal condition. The results showed that the mechano-electrical feedback effects appear to be most important in failing hearts with low ejection fraction.
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Affiliation(s)
- Ani Amar
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Sharon Zlochiver
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Ofer Barnea
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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Quinn TA, Jin H, Lee P, Kohl P. Mechanically Induced Ectopy via Stretch-Activated Cation-Nonselective Channels Is Caused by Local Tissue Deformation and Results in Ventricular Fibrillation if Triggered on the Repolarization Wave Edge (Commotio Cordis). Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.116.004777. [PMID: 28794084 PMCID: PMC5555388 DOI: 10.1161/circep.116.004777] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 07/07/2017] [Indexed: 12/11/2022]
Abstract
Supplemental Digital Content is available in the text. Background— External chest impacts (commotio cordis) can cause mechanically induced premature ventricular excitation (PVEM) and, rarely, ventricular fibrillation (VF). Because block of stretch-sensitive ATP-inactivated potassium channels curtailed VF occurrence in a porcine model of commotio cordis, VF has been suggested to arise from abnormal repolarization caused by stretch activation of potassium channels. Alternatively, VF could result from abnormal excitation by PVEM, overlapping with normal repolarization-related electric heterogeneity. Here, we investigate mechanisms and determinants of PVEM induction and its potential role in commotio cordis–induced VF. Methods and Results— Subcontusional mechanical stimuli were applied to isolated rabbit hearts during optical voltage mapping, combined with pharmacological block of ATP-inactivated potassium or stretch-activated cation-nonselective channels. We demonstrate that local mechanical stimulation reliably triggers PVEM at the contact site, with inducibility predicted by local tissue indentation. PVEM induction is diminished by pharmacological block of stretch-activated cation-nonselective channels. In hearts where electrocardiogram T waves involve a well-defined repolarization edge traversing the epicardium, PVEM can reliably provoke VF if, and only if, the mechanical stimulation site overlaps the repolarization wave edge. In contrast, application of short-lived intraventricular pressure surges neither triggers PVEM nor changes repolarization. ATP-inactivated potassium channel block has no effect on PVEM inducibility per se, but shifts it to later time points by delaying repolarization and prolonging refractoriness. Conclusions— Local mechanical tissue deformation determines PVEM induction via stretch-activation of cation-nonselective channels, with VF induction requiring PVEM overlap with the trailing edge of a normal repolarization wave. This defines a narrow, subject-specific vulnerable window for commotio cordis–induced VF that exists both in time and in space.
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Affiliation(s)
- T Alexander Quinn
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.).
| | - Honghua Jin
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
| | - Peter Lee
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
| | - Peter Kohl
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
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12
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Quinn TA, Kohl P. Rabbit models of cardiac mechano-electric and mechano-mechanical coupling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:110-22. [PMID: 27208698 PMCID: PMC5067302 DOI: 10.1016/j.pbiomolbio.2016.05.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/01/2016] [Indexed: 12/11/2022]
Abstract
Cardiac auto-regulation involves integrated regulatory loops linking electrics and mechanics in the heart. Whereas mechanical activity is usually seen as 'the endpoint' of cardiac auto-regulation, it is important to appreciate that the heart would not function without feed-back from the mechanical environment to cardiac electrical (mechano-electric coupling, MEC) and mechanical (mechano-mechanical coupling, MMC) activity. MEC and MMC contribute to beat-by-beat adaption of cardiac output to physiological demand, and they are involved in various pathological settings, potentially aggravating cardiac dysfunction. Experimental and computational studies using rabbit as a model species have been integral to the development of our current understanding of MEC and MMC. In this paper we review this work, focusing on physiological and pathological implications for cardiac function.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Canada.
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg - Bad Krozingen, Faculty of Medicine, University of Freiburg, Freiburg, Germany; National Heart and Lung Institute, Imperial College London, London, UK
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13
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Abstract
Mechanical forces will have been omnipresent since the origin of life, and living organisms have evolved mechanisms to sense, interpret, and respond to mechanical stimuli. The cardiovascular system in general, and the heart in particular, is exposed to constantly changing mechanical signals, including stretch, compression, bending, and shear. The heart adjusts its performance to the mechanical environment, modifying electrical, mechanical, metabolic, and structural properties over a range of time scales. Many of the underlying regulatory processes are encoded intracardially and are, thus, maintained even in heart transplant recipients. Although mechanosensitivity of heart rhythm has been described in the medical literature for over a century, its molecular mechanisms are incompletely understood. Thanks to modern biophysical and molecular technologies, the roles of mechanical forces in cardiac biology are being explored in more detail, and detailed mechanisms of mechanotransduction have started to emerge. Mechano-gated ion channels are cardiac mechanoreceptors. They give rise to mechano-electric feedback, thought to contribute to normal function, disease development, and, potentially, therapeutic interventions. In this review, we focus on acute mechanical effects on cardiac electrophysiology, explore molecular candidates underlying observed responses, and discuss their pharmaceutical regulation. From this, we identify open research questions and highlight emerging technologies that may help in addressing them.
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Affiliation(s)
- Rémi Peyronnet
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.)
| | - Jeanne M Nerbonne
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.)
| | - Peter Kohl
- From the National Heart and Lung Institute, Imperial College London, United Kingdom (R.P., P.K.); Departments of Developmental Biology and Internal Medicine, Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO (J.M.N.); Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany (R.P., P.K.).
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14
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Arevalo HJ, Boyle PM, Trayanova NA. Computational rabbit models to investigate the initiation, perpetuation, and termination of ventricular arrhythmia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:185-94. [PMID: 27334789 DOI: 10.1016/j.pbiomolbio.2016.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/13/2016] [Indexed: 12/29/2022]
Abstract
Current understanding of cardiac electrophysiology has been greatly aided by computational work performed using rabbit ventricular models. This article reviews the contributions of multiscale models of rabbit ventricles in understanding cardiac arrhythmia mechanisms. This review will provide an overview of multiscale modeling of the rabbit ventricles. It will then highlight works that provide insights into the role of the conduction system, complex geometric structures, and heterogeneous cellular electrophysiology in diseased and healthy rabbit hearts to the initiation and maintenance of ventricular arrhythmia. Finally, it will provide an overview on the contributions of rabbit ventricular modeling on understanding the mechanisms underlying shock-induced defibrillation.
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Affiliation(s)
- Hermenegild J Arevalo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA; Simula Research Laboratory, Oslo, Norway
| | - Patrick M Boyle
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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15
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Vikulova NA, Katsnelson LB, Kursanov AG, Solovyova O, Markhasin VS. Mechano-electric feedback in one-dimensional model of myocardium. J Math Biol 2015; 73:335-66. [PMID: 26687545 DOI: 10.1007/s00285-015-0953-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 07/14/2015] [Indexed: 10/22/2022]
Abstract
We utilized our earlier developed 1D mathematical model of the heart muscle strand to study contribution of the bilateral interactions between excitation and contraction on the cellular and tissue levels to the local and global myocardium function. Numerical experiments on the model showed that an initially uniform strand, formed on the inherently identical cells, became functionally heterogeneous due to the asynchronous excitation via the electrical wave spread. Mechanical interactions between the cells and the mechano-electric feedback beat-to-beat affect the functional characteristics of coupled cardiomyocytes further, adjusting their electrical and mechanical heterogeneity to the activation timing. Model simulations showed that functional heterogeneity increases with an enlarged spatial extension of the myocardial strand (in terms of the longer slack length not a higher stretch of the strand), demonstrating a special role of the heart size in its function. Model analysis suggests that cooperative mechanisms of myofilament calcium activation contribute essentially to the generation of cellular functional heterogeneity in contracting cardiac tissue.
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Affiliation(s)
- Nathalie A Vikulova
- Laboratory of Mathematical Physiology, Institute of Immunology and Physiology, Ekaterinburg, Russia. .,Ural Federal University, Ekaterinburg, Russia.
| | - Leonid B Katsnelson
- Laboratory of Mathematical Physiology, Institute of Immunology and Physiology, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
| | - Alexander G Kursanov
- Laboratory of Mathematical Physiology, Institute of Immunology and Physiology, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
| | - Olga Solovyova
- Laboratory of Mathematical Physiology, Institute of Immunology and Physiology, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
| | - Vladimir S Markhasin
- Laboratory of Mathematical Physiology, Institute of Immunology and Physiology, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
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16
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Burton RAB, Lee P, Casero R, Garny A, Siedlecka U, Schneider JE, Kohl P, Grau V. Three-dimensional histology: tools and application to quantitative assessment of cell-type distribution in rabbit heart. Europace 2015; 16 Suppl 4:iv86-iv95. [PMID: 25362175 PMCID: PMC4217519 DOI: 10.1093/europace/euu234] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Aims Cardiac histo-anatomical organization is a major determinant of function. Changes in tissue structure are a relevant factor in normal and disease development, and form targets of therapeutic interventions. The purpose of this study was to test tools aimed to allow quantitative assessment of cell-type distribution from large histology and magnetic resonance imaging- (MRI) based datasets. Methods and results Rabbit heart fixation during cardioplegic arrest and MRI were followed by serial sectioning of the whole heart and light-microscopic imaging of trichrome-stained tissue. Segmentation techniques developed specifically for this project were applied to segment myocardial tissue in the MRI and histology datasets. In addition, histology slices were segmented into myocytes, connective tissue, and undefined. A bounding surface, containing the whole heart, was established for both MRI and histology. Volumes contained in the bounding surface (called ‘anatomical volume’), as well as that identified as containing any of the above tissue categories (called ‘morphological volume’), were calculated. The anatomical volume was 7.8 cm3 in MRI, and this reduced to 4.9 cm3 after histological processing, representing an ‘anatomical’ shrinkage by 37.2%. The morphological volume decreased by 48% between MRI and histology, highlighting the presence of additional tissue-level shrinkage (e.g. an increase in interstitial cleft space). The ratio of pixels classified as containing myocytes to pixels identified as non-myocytes was roughly 6:1 (61.6 vs. 9.8%; the remaining fraction of 28.6% was ‘undefined’). Conclusion Qualitative and quantitative differentiation between myocytes and connective tissue, using state-of-the-art high-resolution serial histology techniques, allows identification of cell-type distribution in whole-heart datasets. Comparison with MRI illustrates a pronounced reduction in anatomical and morphological volumes during histology processing.
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Affiliation(s)
- Rebecca A B Burton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Peter Lee
- Department of Physics, University of Oxford, Oxford OX1 3RH, UK
| | - Ramón Casero
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, UK
| | - Alan Garny
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Urszula Siedlecka
- The Heart Science Centre, National Heart and Lung Institute, Imperial College London, Harefield UB9 6JH, UK
| | - Jürgen E Schneider
- British Heart Foundation Experimental MR Unit, Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Peter Kohl
- The Heart Science Centre, National Heart and Lung Institute, Imperial College London, Harefield UB9 6JH, UK
| | - Vicente Grau
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, UK
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17
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Images as drivers of progress in cardiac computational modelling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:198-212. [PMID: 25117497 PMCID: PMC4210662 DOI: 10.1016/j.pbiomolbio.2014.08.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 08/02/2014] [Indexed: 11/28/2022]
Abstract
Computational models have become a fundamental tool in cardiac research. Models are evolving to cover multiple scales and physical mechanisms. They are moving towards mechanistic descriptions of personalised structure and function, including effects of natural variability. These developments are underpinned to a large extent by advances in imaging technologies. This article reviews how novel imaging technologies, or the innovative use and extension of established ones, integrate with computational models and drive novel insights into cardiac biophysics. In terms of structural characterization, we discuss how imaging is allowing a wide range of scales to be considered, from cellular levels to whole organs. We analyse how the evolution from structural to functional imaging is opening new avenues for computational models, and in this respect we review methods for measurement of electrical activity, mechanics and flow. Finally, we consider ways in which combined imaging and modelling research is likely to continue advancing cardiac research, and identify some of the main challenges that remain to be solved.
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18
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Solovyova O, Katsnelson LB, Konovalov PV, Kursanov AG, Vikulova NA, Kohl P, Markhasin VS. The cardiac muscle duplex as a method to study myocardial heterogeneity. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:115-28. [PMID: 25106702 PMCID: PMC4210666 DOI: 10.1016/j.pbiomolbio.2014.07.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 07/25/2014] [Indexed: 12/14/2022]
Abstract
This paper reviews the development and application of paired muscle preparations, called duplex, for the investigation of mechanisms and consequences of intra-myocardial electro-mechanical heterogeneity. We illustrate the utility of the underlying combined experimental and computational approach for conceptual development and integration of basic science insight with clinically relevant settings, using previously published and new data. Directions for further study are identified.
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Affiliation(s)
- O Solovyova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia.
| | - L B Katsnelson
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P V Konovalov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - A G Kursanov
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
| | - N A Vikulova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia
| | - P Kohl
- National Heart and Lung Institute, Imperial College of London, Heart Science Centre, Harefield Hospital, Hill End Road, Harefield UB9 6JH, UK; Department of Computer Sciences, University of Oxford, UK
| | - V S Markhasin
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya Str, Ekaterinburg 620049, Russia; Ural Federal University, 19 Mira Str, Ekaterinburg 620002, Russia
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19
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Reed A, Kohl P, Peyronnet R. Molecular candidates for cardiac stretch-activated ion channels. Glob Cardiol Sci Pract 2014; 2014:9-25. [PMID: 25405172 PMCID: PMC4220428 DOI: 10.5339/gcsp.2014.19] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/08/2014] [Indexed: 01/20/2023] Open
Abstract
The heart is a mechanically-active organ that dynamically senses its own mechanical environment. This environment is constantly changing, on a beat-by-beat basis, with additional modulation by respiratory activity and changes in posture or physical activity, and further overlaid with more slowly occurring physiological (e.g. pregnancy, endurance training) or pathological challenges (e.g. pressure or volume overload). Far from being a simple pump, the heart detects changes in mechanical demand and adjusts its performance accordingly, both via heart rate and stroke volume alteration. Many of the underlying regulatory processes are encoded intracardially, and are thus maintained even in heart transplant recipients. Over the last three decades, molecular substrates of cardiac mechanosensitivity have gained increasing recognition in the scientific and clinical communities. Nonetheless, the processes underlying this phenomenon are still poorly understood. Stretch-activated ion channels (SAC) have been identified as one contributor to mechanosensitive autoregulation of the heartbeat. They also appear to play important roles in the development of cardiac pathologies – most notably stretch-induced arrhythmias. As recently discovered, some established cardiac drugs act, in part at least, via mechanotransduction pathways suggesting SAC as potential therapeutic targets. Clearly, identification of the molecular substrate of cardiac SAC is of clinical importance and a number of candidate proteins have been identified. At the same time, experimental studies have revealed variable–and at times contrasting–results regarding their function. Further complication arises from the fact that many ion channels that are not classically defined as SAC, including voltage and ligand-gated ion channels, can respond to mechanical stimulation. Here, we summarise what is known about the molecular substrate of the main candidates for cardiac SAC, before identifying potential further developments in this area of translational research.
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Affiliation(s)
- Alistair Reed
- Medical Sciences Division, University of Oxford, United Kingdom
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20
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Trayanova NA, Boyle PM. Advances in modeling ventricular arrhythmias: from mechanisms to the clinic. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 6:209-24. [PMID: 24375958 DOI: 10.1002/wsbm.1256] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/16/2013] [Accepted: 11/12/2013] [Indexed: 11/12/2022]
Abstract
Modern cardiovascular research has increasingly recognized that heart models and simulation can help interpret an array of experimental data and dissect important mechanisms and interrelationships, with developments rooted in the iterative interaction between modeling and experimentation. This article reviews the progress made in simulating cardiac electrical behavior at the level of the organ and, specifically, in the development of models of ventricular arrhythmias and fibrillation, as well as their termination (defibrillation). The ability to construct multiscale models of ventricular arrhythmias, representing integrative behavior from the molecule to the entire organ, has enabled mechanistic inquiry into the dynamics of ventricular arrhythmias in the diseased myocardium, in understanding drug-induced proarrhythmia, and in the development of new modalities for defibrillation, to name a few. In this article, we also review the initial use of ventricular models of arrhythmia in personalized diagnosis, treatment planning, and prevention of sudden cardiac death. Implementing individualized cardiac simulations at the patient bedside is poised to become one of the most thrilling examples of computational science and engineering approaches in translational medicine.
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Affiliation(s)
- Natalia A Trayanova
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
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21
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Effects of mechano-electric feedback on scroll wave stability in human ventricular fibrillation. PLoS One 2013; 8:e60287. [PMID: 23573245 PMCID: PMC3616032 DOI: 10.1371/journal.pone.0060287] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 02/25/2013] [Indexed: 11/19/2022] Open
Abstract
Recruitment of stretch-activated channels, one of the mechanisms of mechano-electric feedback, has been shown to influence the stability of scroll waves, the waves that underlie reentrant arrhythmias. However, a comprehensive study to examine the effects of recruitment of stretch-activated channels with different reversal potentials and conductances on scroll wave stability has not been undertaken; the mechanisms by which stretch-activated channel opening alters scroll wave stability are also not well understood. The goals of this study were to test the hypothesis that recruitment of stretch-activated channels affects scroll wave stability differently depending on stretch-activated channel reversal potential and channel conductance, and to uncover the relevant mechanisms underlying the observed behaviors. We developed a strongly-coupled model of human ventricular electromechanics that incorporated human ventricular geometry and fiber and sheet orientation reconstructed from MR and diffusion tensor MR images. Since a wide variety of reversal potentials and channel conductances have been reported for stretch-activated channels, two reversal potentials, −60 mV and −10 mV, and a range of channel conductances (0 to 0.07 mS/µF) were implemented. Opening of stretch-activated channels with a reversal potential of −60 mV diminished scroll wave breakup for all values of conductances by flattening heterogeneously the action potential duration restitution curve. Opening of stretch-activated channels with a reversal potential of −10 mV inhibited partially scroll wave breakup at low conductance values (from 0.02 to 0.04 mS/µF) by flattening heterogeneously the conduction velocity restitution relation. For large conductance values (>0.05 mS/µF), recruitment of stretch-activated channels with a reversal potential of −10 mV did not reduce the likelihood of scroll wave breakup because Na channel inactivation in regions of large stretch led to conduction block, which counteracted the increased scroll wave stability due to an overall flatter conduction velocity restitution.
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22
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Quinn TA, Kohl P. Combining wet and dry research: experience with model development for cardiac mechano-electric structure-function studies. Cardiovasc Res 2013; 97:601-11. [PMID: 23334215 PMCID: PMC3583260 DOI: 10.1093/cvr/cvt003] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 01/08/2013] [Accepted: 01/15/2013] [Indexed: 11/17/2022] Open
Abstract
Since the development of the first mathematical cardiac cell model 50 years ago, computational modelling has become an increasingly powerful tool for the analysis of data and for the integration of information related to complex cardiac behaviour. Current models build on decades of iteration between experiment and theory, representing a collective understanding of cardiac function. All models, whether computational, experimental, or conceptual, are simplified representations of reality and, like tools in a toolbox, suitable for specific applications. Their range of applicability can be explored (and expanded) by iterative combination of 'wet' and 'dry' investigation, where experimental or clinical data are used to first build and then validate computational models (allowing integration of previous findings, quantitative assessment of conceptual models, and projection across relevant spatial and temporal scales), while computational simulations are utilized for plausibility assessment, hypotheses-generation, and prediction (thereby defining further experimental research targets). When implemented effectively, this combined wet/dry research approach can support the development of a more complete and cohesive understanding of integrated biological function. This review illustrates the utility of such an approach, based on recent examples of multi-scale studies of cardiac structure and mechano-electric function.
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Affiliation(s)
- T Alexander Quinn
- National Heart and Lung Institute, Imperial College London, Heart Science Centre, Harefield UB9 6JH, UK.
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23
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Rosa AO, Yamaguchi N, Morad M. Mechanical regulation of native and the recombinant calcium channel. Cell Calcium 2013; 53:264-74. [PMID: 23357406 DOI: 10.1016/j.ceca.2012.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 12/25/2012] [Indexed: 11/30/2022]
Abstract
L-type calcium channels are modulated by a host of mechanisms that include voltage, calcium ions (Ca(2+) dependent inactivation and facilitation), cytosolic proteins (CAM, CAMKII, PKA, PKC, etc.), and oxygen radicals. Here we describe yet another Ca(2+) channel regulatory mechanism that is induced by pressure-flow (PF) forces of ∼25dyn/cm(2) producing 35-60% inhibition of channel current. Only brief periods (300ms) of such PF pulses were required to suppress reversibly the current. Recombinant Ca(2+) channels (α1c77/β2a/α2δ and α1c77/β1/α2δ), expressed in HEK293 cells, were similarly suppressed by PF pulses. To examine whether Ca(2+) released by PF pulses triggered from different sub-cellular compartments (SR, ER, mitochondria) underlies the inhibitory effect of PF on the channel current, pharmacological agents and ionic substitutions were employed to probe this possibility. No significant difference in effectiveness of PF pulses to suppress ICa or IBa (used to inhibit CICR) was found between control cells and those exposed to U73122 and 2-APB (PLC and IP3R pathway modulators), thapsigargin and BAPTA (SERCA2a modulator), dinitrophenol, FCCP and Ru360 (mitochondrial inhibitors), l-NAME (NOS inhibitor signaling), cAMP and Pertussis toxin (Gi protein modulator). We concluded that the rapid and reversible modulation of the Ca(2+) channel by PF pulses is independent of intracellular release of Ca(2+) and Ca(2+) dependent inactivation of the channel and may represent direct mechanical regulatory effect on the channel protein in addition to previously reported Ca(2+)-release or entry dependent mechanism.
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Affiliation(s)
- Angelo O Rosa
- Cardiac Signaling Center, University of South Carolina, Charleston, SC 29425, USA
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24
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Gauthier LD, Greenstein JL, Winslow RL. Toward an integrative computational model of the Guinea pig cardiac myocyte. Front Physiol 2012; 3:244. [PMID: 22783206 PMCID: PMC3389778 DOI: 10.3389/fphys.2012.00244] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/14/2012] [Indexed: 11/22/2022] Open
Abstract
The local control theory of excitation-contraction (EC) coupling asserts that regulation of calcium (Ca2+) release occurs at the nanodomain level, where openings of single L-type Ca2+ channels (LCCs) trigger openings of small clusters of ryanodine receptors (RyRs) co-localized within the dyad. A consequence of local control is that the whole-cell Ca2+ transient is a smooth continuous function of influx of Ca2+ through LCCs. While this so-called graded release property has been known for some time, its functional importance to the integrated behavior of the cardiac ventricular myocyte has not been fully appreciated. We previously formulated a biophysically based model, in which LCCs and RyRs interact via a coarse-grained representation of the dyadic space. The model captures key features of local control using a low-dimensional system of ordinary differential equations. Voltage-dependent gain and graded Ca2+ release are emergent properties of this model by virtue of the fact that model formulation is closely based on the sub-cellular basis of local control. In this current work, we have incorporated this graded release model into a prior model of guinea pig ventricular myocyte electrophysiology, metabolism, and isometric force production. The resulting integrative model predicts the experimentally observed causal relationship between action potential (AP) shape and timing of Ca2+ and force transients, a relationship that is not explained by models lacking the graded release property. Model results suggest that even relatively subtle changes in AP morphology that may result, for example, from remodeling of membrane transporter expression in disease or spatial variation in cell properties, may have major impact on the temporal waveform of Ca2+ transients, thus influencing tissue level electromechanical function.
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Affiliation(s)
- Laura Doyle Gauthier
- Department of Biomedical Engineering, Institute for Computational Medicine, The Johns Hopkins University School of Medicine and Whiting School of Engineering Baltimore, MD, USA
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25
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Dau N, Cavanaugh J, Bir C, Link M. Evaluation of injury criteria for the prediction of commotio cordis from lacrosse ball impacts. STAPP CAR CRASH JOURNAL 2011; 55:251-279. [PMID: 22869311 DOI: 10.4271/2011-22-0010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Commotio Cordis (CC) is the second leading cause of mortality in youth sports. Impacts occurring directly over the left ventricle (LV) during a vulnerable period of the cardiac cycle can cause ventricular fibrillation (VF), which results in CC. In order to better understand the pathophysiology of CC, and develop a mechanical model for CC, appropriate injury criteria need to be developed. This effort consisted of impacts to seventeen juvenile porcine specimens (mass 21-45 kg). Impacts were delivered over the cardiac silhouette during the venerable period of the cardiac cycle. Four impact speeds were used: 13.4, 17.9, 22.4, and 26.8 m/s. The impactor was a lacrosse ball on an aluminum shaft instrumented with an accelerometer (mass 188 g-215 g). The impacts were recorded using high-speed video. LV pressure was measured with a catheter. Univariate binary logistic regression analyses were performed to evaluate the predictive ability of ten injury criteria. A total of 187 impacts were used in the analysis. The criteria were evaluated on their predictive ability based on Somers' D (D) and Goodman-Kruskal gamma (γ). Injury risk functions were created for all criteria using a 2-parameter Weibull distribution using survival analysis. The best criteria for predicting CC were impact force (D=0.52, and γ=0.52) force*compression (D=0.49, and γ=0.49), and impact power (D=0.49, and γ=0.49). All of these criteria proved significant in predicting the probability of CC from projectile impacts in youth sports (p<0.01). Force proved to be the most predictive of the ten criteria evaluated.
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Affiliation(s)
- Nathan Dau
- Wayne State University Bioengineering Center, Detroit, MI 48201, USA.
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26
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Trayanova NA, Rice JJ. Cardiac electromechanical models: from cell to organ. Front Physiol 2011; 2:43. [PMID: 21886622 PMCID: PMC3154390 DOI: 10.3389/fphys.2011.00043] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 07/12/2011] [Indexed: 11/13/2022] Open
Abstract
The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computational physiology and medicine. This review focuses on electromechanical (EM) models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single-cell models and the second half addresses organ models. At the subcellular level, myofilament models represent actin–myosin interaction and Ca-based activation. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered to be the cellular basis of the Frank–Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of the field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction–diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and defibrillation.
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Affiliation(s)
- Natalia A Trayanova
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
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27
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Lee P, Bollensdorff C, Quinn TA, Wuskell JP, Loew LM, Kohl P. Single-sensor system for spatially resolved, continuous, and multiparametric optical mapping of cardiac tissue. Heart Rhythm 2011; 8:1482-91. [PMID: 21459161 PMCID: PMC3167353 DOI: 10.1016/j.hrthm.2011.03.061] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 03/28/2011] [Indexed: 11/28/2022]
Abstract
Background Simultaneous optical mapping of multiple electrophysiologically relevant parameters in living myocardium is desirable for integrative exploration of mechanisms underlying heart rhythm generation under normal and pathophysiologic conditions. Current multiparametric methods are technically challenging, usually involving multiple sensors and moving parts, which contributes to high logistic and economic thresholds that prevent easy application of the technique. Objective The purpose of this study was to develop a simple, affordable, and effective method for spatially resolved, continuous, simultaneous, and multiparametric optical mapping of the heart, using a single camera. Methods We present a new method to simultaneously monitor multiple parameters using inexpensive off-the-shelf electronic components and no moving parts. The system comprises a single camera, commercially available optical filters, and light-emitting diodes (LEDs), integrated via microcontroller-based electronics for frame-accurate illumination of the tissue. For proof of principle, we illustrate measurement of four parameters, suitable for ratiometric mapping of membrane potential (di-4-ANBDQPQ) and intracellular free calcium (fura-2), in an isolated Langendorff-perfused rat heart during sinus rhythm and ectopy, induced by local electrical or mechanical stimulation. Results The pilot application demonstrates suitability of this imaging approach for heart rhythm research in the isolated heart. In addition, locally induced excitation, whether stimulated electrically or mechanically, gives rise to similar ventricular propagation patterns. Conclusion Combining an affordable camera with suitable optical filters and microprocessor-controlled LEDs, single-sensor multiparametric optical mapping can be practically implemented in a simple yet powerful configuration and applied to heart rhythm research. The moderate system complexity and component cost is destined to lower the threshold to broader application of functional imaging and to ease implementation of more complex optical mapping approaches, such as multiparametric panoramic imaging. A proof-of-principle application confirmed that although electrically and mechanically induced excitation occur by different mechanisms, their electrophysiologic consequences downstream from the point of activation are not dissimilar.
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Affiliation(s)
- Peter Lee
- Cardiac Mechano-Electric Feedback Lab, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Abstract
Recent developments in cardiac simulation have rendered the heart the most highly integrated example of a virtual organ. We are on the brink of a revolution in cardiac research, one in which computational modeling of proteins, cells, tissues, and the organ permit linking genomic and proteomic information to the integrated organ behavior, in the quest for a quantitative understanding of the functioning of the heart in health and disease. The goal of this review is to assess the existing state-of-the-art in whole-heart modeling and the plethora of its applications in cardiac research. General whole-heart modeling approaches are presented, and the applications of whole-heart models in cardiac electrophysiology and electromechanics research are reviewed. The article showcases the contributions that whole-heart modeling and simulation have made to our understanding of the functioning of the heart. A summary of the future developments envisioned for the field of cardiac simulation and modeling is also presented. Biophysically based computational modeling of the heart, applied to human heart physiology and the diagnosis and treatment of cardiac disease, has the potential to dramatically change 21st century cardiac research and the field of cardiology.
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Affiliation(s)
- Natalia A Trayanova
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21218, USA.
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Abstract
One of the most important components of mechanoelectric coupling is stretch-activated channels, sarcolemmal channels that open upon mechanical stimuli. Uncovering the mechanisms by which stretch-activated channels contribute to ventricular arrhythmogenesis under a variety of pathologic conditions is hampered by the lack of experimental methodologies that can record the 3-dimensional electromechanical activity simultaneously at high spatiotemporal resolution. Computer modeling provides such an opportunity. The goal of this review is to illustrate the utility of sophisticated, physiologically realistic, whole heart computer simulations in determining the role of mechanoelectric coupling in ventricular arrhythmogenesis. We first present the various ways by which stretch-activated channels have been modeled and demonstrate how these channels affect cardiac electrophysiologic properties. Next, we use an electrophysiologic model of the rabbit ventricles to understand how so-called commotio cordis, the mechanical impact to the precordial region of the heart, can initiate ventricular tachycardia via the recruitment of stretch-activated channels. Using the same model, we also provide mechanistic insight into the termination of arrhythmias by precordial thump under normal and globally ischemic conditions. Lastly, we use a novel anatomically realistic dynamic 3-dimensional coupled electromechanical model of the rabbit ventricles to gain insight into the role of electromechanical dysfunction in arrhythmogenesis during acute regional ischemia.
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Tran TA, Le Guennec JY, Babuty D, Bougnoux P, Tranquart F, Bouakaz A. On the mechanisms of ultrasound contrast agents-induced arrhythmias. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:1050-1056. [PMID: 19195768 DOI: 10.1016/j.ultrasmedbio.2008.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 11/02/2008] [Accepted: 11/20/2008] [Indexed: 05/27/2023]
Abstract
Recent reports have shown that imaging hard-shelled ultrasound (US) contrast agents at high mechanical indices engenders premature ventricular contractions (PVCs). We have shown that the oscillations of microbubbles next to a cell induce a mechanical pressure on its membrane resulting in the activation of stretch activated channels (SAC). The aim of this study is to demonstrate, in vivo and in vitro, the relationship between PVCs and SAC opening. Five anesthetized rats were used. PVCs were created in vivo with (1) US and a diluted solution of contrast microbubbles injected intravenously through the tail vein at a rate of 0.5 mL per min and (2) a manually induced mechanical stimulus, which consisted of stimulations by a flexible catheter introduced into the rat aorta and pushed until the left ventricle. PVCs were quantified through ECG measurements. In vitro experiments consisted of patch Clamp measurements on HL-1 heart cell line. The stimulation was carried out either manually with a glass rod or with US and microbubbles. For both in vivo and in vitro experiments, US consisted of 40-cycle waveforms at 1 MHz and peak negative pressures up to 300 kPa and exposure time varied from 1 to 2 min. We should emphasize that these parameters are different from those used in diagnostic conditions. In vivo, microbubbles and US at 300 kPa induced modification of rat's ECG while pressures below 300 kPa did not induce any PVC. US alone did not modify the rat's ECG. Similar PVCs were also created when stimulation with a catheter was applied. Regular heart beat rate was recovered immediately after the stimulation was stopped. In vitro, the mechanical stretch induced a cell membrane depolarization due to SAC opening. Similar effect was observed with US and microbubbles. The cell potential returned to its initial value when the stimulation was released. In conclusion, we presume that PVCs are generated through a cascade of events characterized by a mechanical action of oscillating microbubbles, opening of stretch activated ion channels, membrane depolarization and triggering of action potentials.
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Vigmond E, Vadakkumpadan F, Gurev V, Arevalo H, Deo M, Plank G, Trayanova N. Towards predictive modelling of the electrophysiology of the heart. Exp Physiol 2009; 94:563-77. [PMID: 19270037 DOI: 10.1113/expphysiol.2008.044073] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The simulation of cardiac electrical function is an example of a successful integrative multiscale modelling approach that is directly relevant to human disease. Today we stand at the threshold of a new era, in which anatomically detailed, tomographically reconstructed models are being developed that integrate from the ion channel to the electromechanical interactions in the intact heart. Such models hold high promise for interpretation of clinical and physiological measurements, for improving the basic understanding of the mechanisms of dysfunction in disease, such as arrhythmias, myocardial ischaemia and heart failure, and for the development and performance optimization of medical devices. The goal of this article is to present an overview of current state-of-art advances towards predictive computational modelling of the heart as developed recently by the authors of this article. We first outline the methodology for constructing electrophysiological models of the heart. We then provide three examples that demonstrate the use of these models, focusing specifically on the mechanisms for arrhythmogenesis and defibrillation in the heart. These include: (1) uncovering the role of ventricular structure in defibrillation; (2) examining the contribution of Purkinje fibres to the failure of the shock; and (3) using magnetic resonance imaging reconstructed heart models to investigate the re-entrant circuits formed in the presence of an infarct scar.
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Affiliation(s)
- Edward Vigmond
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
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Lucena JS, Rico A, Salguero M, Blanco M, Vázquez R. Commotio cordis as a result of a fight: Report of a case considered to be imprudent homicide. Forensic Sci Int 2008; 177:e1-4. [DOI: 10.1016/j.forsciint.2007.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 01/23/2007] [Accepted: 09/17/2007] [Indexed: 11/29/2022]
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Southern J, Pitt-Francis J, Whiteley J, Stokeley D, Kobashi H, Nobes R, Kadooka Y, Gavaghan D. Multi-scale computational modelling in biology and physiology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 96:60-89. [PMID: 17888502 PMCID: PMC7112301 DOI: 10.1016/j.pbiomolbio.2007.07.019] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in biotechnology and the availability of ever more powerful computers have led to the formulation of increasingly complex models at all levels of biology. One of the main aims of systems biology is to couple these together to produce integrated models across multiple spatial scales and physical processes. In this review, we formulate a definition of multi-scale in terms of levels of biological organisation and describe the types of model that are found at each level. Key issues that arise in trying to formulate and solve multi-scale and multi-physics models are considered and examples of how these issues have been addressed are given for two of the more mature fields in computational biology: the molecular dynamics of ion channels and cardiac modelling. As even more complex models are developed over the coming few years, it will be necessary to develop new methods to model them (in particular in coupling across the interface between stochastic and deterministic processes) and new techniques will be required to compute their solutions efficiently on massively parallel computers. We outline how we envisage these developments occurring.
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Affiliation(s)
- James Southern
- Fujitsu Laboratories of Europe Ltd, Hayes Park Central, Hayes End Road, Hayes, Middlesex UB4 8FE, UK.
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Li W, Kohl P, Trayanova N. Myocardial ischemia lowers precordial thump efficacy: an inquiry into mechanisms using three-dimensional simulations. Heart Rhythm 2006; 3:179-86. [PMID: 16443533 DOI: 10.1016/j.hrthm.2005.10.033] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Accepted: 10/31/2005] [Indexed: 11/20/2022]
Abstract
BACKGROUND Precordial thump is the first International Liaison Committee on Resuscitation-prescribed procedure for advanced life support in witnessed cardiac arrest. Success rates vary and, according to clinical evidence, are significantly reduced under ischemic conditions. OBJECTIVES The purpose of this study was to elucidate the mechanisms involved in termination of ventricular tachycardia (VT) by precordial thump and its decreased rate of success in ischemia using a three-dimensional realistic model of electrical behavior in the rabbit ventricles. METHODS The electrophysiologic effect of precordial thump was represented by recruitment of mechanosensitive channels in the regions affected by precordial thump. In normoxia, precordial thump opened cation nonselective stretch-activated channels (SAC-NS, reversal potential -20 mV). In ischemia, precordial thump was assumed to additionally activate ATP-sensitive K+ (K(ATP)) channels (reversal potential -95 mV). Ten randomly selected cases of VT were used, and for each case the effect of precordial thump on VT was examined for normoxia and under ischemic conditions of varying severity. RESULTS Precordial thump was found to have a 60% success rate in normoxia and 30% in ischemia. Results demonstrate that precordial thump-induced SAC-NS opening in normoxia reduced heterogeneity in transmembrane potential by partially repolarizing excited tissue and depolarizing resting myocardium, potentially causing foci of excitation that eradicate the excitable gap, thus facilitating VT termination. Decreased precordial thump efficacy in ischemia was caused by recruitment of K(ATP), which diminished the depolarizing effect of SAC-NS on resting tissue and caused pronounced action potential shortening, thus facilitating establishment of reentry. CONCLUSION This study provides mechanistic insight into precordial thump mechanisms and its reduced clinical utility in patients with myocardial ischemia.
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Affiliation(s)
- Weihui Li
- Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA.
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