151
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Valiunas V, Cohen IS, Brink PR, Clausen C. A study of the outward background current conductance g K1, the pacemaker current conductance g f, and the gap junction conductance g j as determinants of biological pacing in single cells and in a two-cell syncytium using the dynamic clamp. Pflugers Arch 2020; 472:561-570. [PMID: 32415460 DOI: 10.1007/s00424-020-02378-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/21/2022]
Abstract
We previously demonstrated that a two-cell syncytium, composed of a ventricular myocyte and an mHCN2 expressing cell, recapitulated most properties of in vivo biological pacing induced by mHCN2-transfected hMSCs in the canine ventricle. Here, we use the two-cell syncytium, employing dynamic clamp, to study the roles of gf (pacemaker conductance), gK1 (background K+ conductance), and gj (intercellular coupling conductance) in biological pacing. We studied gf and gK1 in single HEK293 cells expressing cardiac sodium current channel Nav1.5 (SCN5A). At fixed gf, increasing gK1 hyperpolarized the cell and initiated pacing. As gK1 increased, rate increased, then decreased, finally ceasing at membrane potentials near EK. At fixed gK1, increasing gf depolarized the cell and initiated pacing. With increasing gf, rate increased reaching a plateau, then decreased, ceasing at a depolarized membrane potential. We studied gj via virtual coupling with two non-adjacent cells, a driver (HEK293 cell) in which gK1 and gf were injected without SCN5A and a follower (HEK293 cell), expressing SCN5A. At the chosen values of gK1 and gf oscillations initiated in the driver, when gj was increased synchronized pacing began, which then decreased by about 35% as gj approached 20 nS. Virtual uncoupling yielded similar insights into gj. We also studied subthreshold oscillations in physically and virtually coupled cells. When coupling was insufficient to induce pacing, passive spread of the oscillations occurred in the follower. These results show a non-monotonic relationship between gK1, gf, gj, and pacing. Further, oscillations can be generated by gK1 and gf in the absence of SCN5A.
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Affiliation(s)
- Virginijus Valiunas
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY, 11794-8661, USA.
| | - Ira S Cohen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY, 11794-8661, USA
| | - Peter R Brink
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY, 11794-8661, USA
| | - Chris Clausen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY, 11794-8661, USA
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152
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Slotvitsky MM, Tsvelaya VA, Podgurskaya AD, Agladze KI. Formation of an electrical coupling between differentiating cardiomyocytes. Sci Rep 2020; 10:7774. [PMID: 32385315 PMCID: PMC7210299 DOI: 10.1038/s41598-020-64581-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/08/2020] [Indexed: 01/02/2023] Open
Abstract
Human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) serve as an indispensable platform for the study of human cardiovascular disease is human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs). While the possibility of reproducing rare pathologies, patient-specific selection of drugs, and other issues concerning single cardiomyocytes have been well studied, little attention has been paid to the properties of the whole syncytium of CMs, in which both the functionality of individual cells and the distribution of electrophysiological connections between them are essential. The aim of this work is to directly study the ability of hiPSC-CMs to form a functional syncytium that can stably conduct an excitation wave. For that purpose, syncytium forming hiPSC-CMs were harvested and seeded (transferred) on a new substrate on different days of differentiation. The excitation conduction in a sample was characterized by the stability of the wavefront using optical mapping data. We found that the cells transferred before the 20th day of differentiation were able to organize a functional syncytium capable of further development and stable excitation conduction at high stimulation frequencies, while the cells transferred after 20 days did not form a homogeneous syncytium, and multiple instabilities of the propagating wavefront were observed with the possibility of reentry formation.
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Affiliation(s)
- M M Slotvitsky
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russian Federation
| | - V A Tsvelaya
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russian Federation
| | - A D Podgurskaya
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russian Federation
| | - K I Agladze
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141700, Russian Federation. .,M.F. Vladimirsky Moscow Regional Clinical Research Institute, Moscow, 129110, Russian Federation.
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153
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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154
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De Simone SA, Moyle S, Buccarello A, Dellenbach C, Kucera JP, Rohr S. The Role of Membrane Capacitance in Cardiac Impulse Conduction: An Optogenetic Study With Non-excitable Cells Coupled to Cardiomyocytes. Front Physiol 2020; 11:194. [PMID: 32273847 PMCID: PMC7113375 DOI: 10.3389/fphys.2020.00194] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/20/2020] [Indexed: 12/15/2022] Open
Abstract
Non-excitable cells (NECs) such as cardiac myofibroblasts that are electrotonically coupled to cardiomyocytes affect conduction velocity (θ) by representing a capacitive load (CL: increased membrane to be charged) and a resistive load (RL: partial depolarization of coupled cardiomyocytes). In this study, we untangled the relative contributions of both loading modalities to NEC-dependent arrhythmogenic conduction slowing. Discrimination between CL and RL was achieved by reversibly removing the RL component by light activation of the halorhodopsin-based hyperpolarizing membrane voltage actuator eNpHR3.0-eYFP (enhanced yellow fluorescent protein) expressed in communication-competent fibroblast-like NIH3T3 cells (3T3HR cells) that served as a model of coupled NECs. Experiments were conducted with strands of neonatal rat ventricular cardiomyocytes coated at increasing densities with 3T3HR cells. Impulse conduction along preparations stimulated at 2.5 Hz was assessed with multielectrode arrays. The relative density of 3T3HR cells was determined by dividing the area showing eYFP fluorescence by the area covered with cardiomyocytes [coverage factor (CF)]. Compared to cardiomyocytes, 3T3HR cells exhibited a depolarized membrane potential (−34 mV) that was shifted to −104 mV during activation of halorhodopsin. Without illumination, 3T3HR cells slowed θ along the preparations from ∼330 mm/s (control cardiomyocyte strands) to ∼100 mm/s (CF = ∼0.6). Illumination of the preparation increased the electrogram amplitudes and induced partial recovery of θ at CF > 0.3. Computer simulations demonstrated that the θ deficit observed during illumination was attributable in full to the CL represented by coupled 3T3HR cells with θ showing a power-law relationship to capacitance with an exponent of −0.78 (simulations) and −0.99 (experiments). The relative contribution of CL and RL to conduction slowing changed as a function of CF with CL dominating at CF ≤ ∼0.3, both mechanisms being equally important at CF = ∼0.5, and RL dominating over CL at CF > 0.5. The finding that RL did not affect θ at CFs ≤ 0.3 is explained by the circumstance that, at the respective moderate levels of cardiomyocyte depolarization, supernormal conduction stabilized propagation. The findings provide experimental estimates for the dependence of θ on membrane capacitance in general and suggest that the myocardium can absorb moderate numbers of electrotonically coupled NECs without showing substantial alterations of θ.
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Affiliation(s)
- Stefano Andrea De Simone
- Laboratory of Cellular Optics II, Department of Physiology, University of Bern, Bern, Switzerland
| | - Sarah Moyle
- Laboratory of Cellular Optics II, Department of Physiology, University of Bern, Bern, Switzerland
| | - Andrea Buccarello
- Integrative Cardiac Bioelectricity Group, Department of Physiology, University of Bern, Bern, Switzerland
| | - Christian Dellenbach
- Laboratory of Cellular Optics II, Department of Physiology, University of Bern, Bern, Switzerland
| | - Jan Pavel Kucera
- Integrative Cardiac Bioelectricity Group, Department of Physiology, University of Bern, Bern, Switzerland
| | - Stephan Rohr
- Laboratory of Cellular Optics II, Department of Physiology, University of Bern, Bern, Switzerland
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155
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Loss of insulin signaling may contribute to atrial fibrillation and atrial electrical remodeling in type 1 diabetes. Proc Natl Acad Sci U S A 2020; 117:7990-8000. [PMID: 32198206 DOI: 10.1073/pnas.1914853117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Atrial fibrillation (AF) is prevalent in diabetes mellitus (DM); however, the basis for this is unknown. This study investigated AF susceptibility and atrial electrophysiology in type 1 diabetic Akita mice using in vivo intracardiac electrophysiology, high-resolution optical mapping in atrial preparations, and patch clamping in isolated atrial myocytes. qPCR and western blotting were used to assess ion channel expression. Akita mice were highly susceptible to AF in association with increased P-wave duration and slowed atrial conduction velocity. In a second model of type 1 DM, mice treated with streptozotocin (STZ) showed a similar increase in susceptibility to AF. Chronic insulin treatment reduced susceptibility and duration of AF and shortened P-wave duration in Akita mice. Atrial action potential (AP) morphology was altered in Akita mice due to a reduction in upstroke velocity and increases in AP duration. In Akita mice, atrial Na+ current (INa) and repolarizing K+ current (IK) carried by voltage gated K+ (Kv1.5) channels were reduced. The reduction in INa occurred in association with reduced expression of SCN5a and voltage gated Na+ (NaV1.5) channels as well as a shift in INa activation kinetics. Insulin potently and selectively increased INa in Akita mice without affecting IK Chronic insulin treatment increased INa in association with increased expression of NaV1.5. Acute insulin also increased INa, although to a smaller extent, due to enhanced insulin signaling via phosphatidylinositol 3,4,5-triphosphate (PIP3). Our study reveals a critical, selective role for insulin in regulating atrial INa, which impacts susceptibility to AF in type 1 DM.
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156
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Jiang B, Yan L, Shamul JG, Hakun M, He X. Stem cell therapy of myocardial infarction: a promising opportunity in bioengineering. ADVANCED THERAPEUTICS 2020; 3:1900182. [PMID: 33665356 PMCID: PMC7928435 DOI: 10.1002/adtp.201900182] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Indexed: 02/06/2023]
Abstract
Myocardial infarction (MI) is a life-threatening disease resulting from irreversible death of cardiomyocytes (CMs) and weakening of the heart blood-pumping function. Stem cell-based therapies have been studied for MI treatment over the last two decades with promising outcome. In this review, we critically summarize the past work in this field to elucidate the advantages and disadvantages of treating MI using pluripotent stem cells (PSCs) including both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), adult stem cells, and cardiac progenitor cells. The main advantage of the latter is their cytokine production capability to modulate immune responses and control the progression of healing. However, human adult stem cells have very limited (if not 'no') capacity to differentiate into functional CMs in vitro or in vivo. In contrast, PSCs can be differentiated into functional CMs although the protocols for the cardiac differentiation of PSCs are mainly for adherent cells under 2D culture. Derivation of PSC-CMs in 3D, allowing for large-scale production of CMs via modulation of the Wnt/β-catenin signal pathway with defined chemicals and medium, may be desired for clinical translation. Furthermore, the technology of purification and maturation of the PSC-CMs may need further improvements to eliminate teratoma formation after in vivo implantation of the PSC-CMs for treating MI. In addition, in vitro derived PSC-CMs may have mechanical and electrical mismatch with the patient's cardiac tissue, which causes arrhythmia. This supports the use of PSC-derived cells committed to cardiac lineage without beating for implantation to treat MI. In this case, the PSC derived cells may utilize the mechanical, electrical, and chemical cues in the heart to further differentiate into mature/functional CMs in situ. Another major challenge facing stem cell therapy of MI is the low retention/survival of stem cells or their derivatives (e.g., PSC-CMs) in the heart for MI treatment after injection in vivo. This may be resolved by using biomaterials to engineer stem cells for reduced immunogenicity, immobilization of the cells in the heart, and increased integration with the host cardiac tissue. Biomaterials have also been applied in the derivation of CMs in vitro to increase the efficiency and maturation of differentiation. Collectively, a lot has been learned from the past failure of simply injecting intact stem cells or their derivatives in vivo for treating MI, and bioengineering stem cells with biomaterials is expected to be a valuable strategy for advancing stem cell therapy towards its widespread application for treating MI in the clinic.
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Affiliation(s)
- Bin Jiang
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Li Yan
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - James G Shamul
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Maxwell Hakun
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
| | - Xiaoming He
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
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157
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Schwach V, Passier R. Native cardiac environment and its impact on engineering cardiac tissue. Biomater Sci 2020; 7:3566-3580. [PMID: 31338495 DOI: 10.1039/c8bm01348a] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) generally have an immature fetal-like phenotype when directly compared to isolated CMs from human hearts, despite significant advance in differentiation of human pluripotent stem cells (hPSCs) to multiple cardiac lineages. Therefore, hPSC-CMs may not accurately mimic all facets of healthy and diseased human adult CMs. During embryonic development, the cardiac extracellular matrix (ECM) experiences a gradual assembly of matrix proteins that transits along the maturation of CMs. Mimicking these dynamic stages may contribute to hPSC-CMs maturation in vitro. Thus, in this review, we describe the progressive build-up of the cardiac ECM during embryonic development, the ECM of the adult human heart and the application of natural and synthetic biomaterials for cardiac tissue engineering with hPSC-CMs.
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Affiliation(s)
- Verena Schwach
- Dept of Applied Stem Cell Technologies, TechMed Centre, University of Twente, The Netherlands.
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158
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Abstract
Determining optimal treatment strategies for complex arrhythmogenesis in AF is confounded by the lack of consensus regarding the mechanisms causing AF. Studies report different mechanisms for AF, ranging from hierarchical drivers to anarchical multiple activation wavelets. Differences in the assessment of AF mechanisms are likely due to AF being recorded across diverse models using different investigational tools, spatial scales and clinical populations. The authors review different AF mechanisms, including anatomical and functional re-entry, hierarchical drivers and anarchical multiple wavelets. They then describe different cardiac mapping techniques and analysis tools, including activation mapping, phase mapping and fibrosis identification. They explain and review different data challenges, including differences between recording devices in spatial and temporal resolutions, spatial coverage and recording surface, and report clinical outcomes using different data modalities. They suggest future research directions for investigating the mechanisms underlying human AF.
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Affiliation(s)
- Caroline H Roney
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.,Imperial Centre for Cardiac Engineering, Imperial College London, London, UK
| | - Andrew L Wit
- Imperial Centre for Cardiac Engineering, Imperial College London, London, UK.,Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, NY, US
| | - Nicholas S Peters
- Imperial Centre for Cardiac Engineering, Imperial College London, London, UK.,National Heart and Lung Institute, Imperial College London, London, UK
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159
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Second-degree atrioventricular block in an adolescent with an acute alcohol intoxication. Am J Emerg Med 2020; 38:407.e1-407.e3. [DOI: 10.1016/j.ajem.2019.158419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/24/2019] [Accepted: 08/28/2019] [Indexed: 11/23/2022] Open
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160
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Yao G, Duan D. High-resolution 3D tractography of fibrous tissue based on polarization-sensitive optical coherence tomography. Exp Biol Med (Maywood) 2020; 245:273-281. [PMID: 31813275 PMCID: PMC7370596 DOI: 10.1177/1535370219894332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Fibrous tissues play important roles in many parts of the body. Their highly organized directional structure is essential in achieving their normal biomechanical and physiological functions. Disruption of the typical fiber organization in these tissues is often linked to pathological changes and disease progression. Tractography is a specialized imaging method that can reveal the detailed fiber architecture. Here, we review recent developments in high-resolution optical tractography using Jones matrix polarization-sensitive optical coherence tomography. We also illustrate the use of this new tractography technology for visualizing depth-resolved, three-dimensional fibrous structures and quantifying tissue damages in several major fibrous tissues.
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Affiliation(s)
- Gang Yao
- Department of Biomedical, Biological & Chemical Engineering, University of Missouri, Columbia, MO 65211, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
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161
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Benson AP, Stevenson-Cocks HJ, Whittaker DG, White E, Colman MA. Multi-scale approaches for the simulation of cardiac electrophysiology: II - Tissue-level structure and function. Methods 2020; 185:60-81. [PMID: 31988002 DOI: 10.1016/j.ymeth.2020.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/15/2019] [Accepted: 01/14/2020] [Indexed: 02/06/2023] Open
Abstract
Computational models of the heart, from cell-level models, through one-, two- and three-dimensional tissue-level simplifications, to biophysically-detailed three-dimensional models of the ventricles, atria or whole heart, allow the simulation of excitation and propagation of this excitation, and have provided remarkable insight into the normal and pathological functioning of the heart. In this article we present equations for modelling cellular excitation (i.e. the cell action potential) from both a phenomenological and a biophysical perspective. Hodgkin-Huxley formalism is discussed, along with the current generation of biophysically-detailed cardiac cell models. Alternative Markovian formulations for modelling ionic currents are also presented. Equations describing propagation of this cellular excitation, through one-, two- and three-dimensional idealised or realistic tissues, are then presented. For all types of model, from cell to tissue, methods for discretisation and integration of the underlying equations are discussed. The article finishes with a discussion of two tissue-level experimental imaging techniques - diffusion tensor magnetic resonance imaging and optical imaging - that can be used to provide data for parameterisation and validation of cell- and tissue-level cardiac models.
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Affiliation(s)
- Alan P Benson
- School of Biomedical Sciences University of Leeds, Leeds LS2 9JT, UK.
| | | | - Dominic G Whittaker
- School of Biomedical Sciences University of Leeds, Leeds LS2 9JT, UK; School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Ed White
- School of Biomedical Sciences University of Leeds, Leeds LS2 9JT, UK
| | - Michael A Colman
- School of Biomedical Sciences University of Leeds, Leeds LS2 9JT, UK
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162
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Huang CLH, Wu L, Jeevaratnam K, Lei M. Update on antiarrhythmic drug pharmacology. J Cardiovasc Electrophysiol 2020; 31:579-592. [PMID: 31930579 DOI: 10.1111/jce.14347] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/22/2019] [Accepted: 01/03/2020] [Indexed: 12/28/2022]
Abstract
Cardiac arrhythmias constitute a major public health problem. Pharmacological intervention remains mainstay to their clinical management. This, in turn, depends upon systematic drug classification schemes relating their molecular, cellular, and systems effects to clinical indications and therapeutic actions. This approach was first pioneered in the 1960s Vaughan-Williams classification. Subsequent progress in cardiac electrophysiological understanding led to a lag between the fundamental science and its clinical translation, partly addressed by The working group of the European Society of Cardiology (1991), which, however, did not emerge with formal classifications. We here utilize the recent Revised Oxford Classification Scheme to review antiarrhythmic drug pharmacology. We survey drugs and therapeutic targets offered by the more recently characterized ion channels, transporters, receptors, intracellular Ca2+ handling, and cell signaling molecules. These are organized into their strategic roles in cardiac electrophysiological function. Following analysis of the arrhythmic process itself, we consider (a) pharmacological agents directly targeting membrane function, particularly the Na+ and K+ ion channels underlying depolarizing and repolarizing events in the cardiac action potential. (b) We also consider agents that modify autonomic activity that, in turn, affects both the membrane and (c) the Ca2+ homeostatic and excitation-contraction coupling processes linking membrane excitation to contractile activation. Finally, we consider (d) drugs acting on more upstream energetic and structural remodeling processes currently the subject of clinical trials. Such systematic correlations of drug actions and arrhythmic mechanisms at different molecular to systems levels of cardiac function will facilitate current and future antiarrhythmic therapy.
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Affiliation(s)
- Christopher L-H Huang
- Department of Biochemistry and Physiological Laboratory, University of Cambridge, Cambridge, UK.,Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Lin Wu
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,Department of Cardiology, Peking University First Hospital, Beijing, China
| | | | - Ming Lei
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,Department of Pharmacology, University of Oxford, Oxford, UK
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163
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Abramochkin DV, Matchkov V, Wang T. A characterization of the electrophysiological properties of the cardiomyocytes from ventricle, atrium and sinus venosus of the snake heart. J Comp Physiol B 2019; 190:63-73. [DOI: 10.1007/s00360-019-01253-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/15/2019] [Accepted: 12/08/2019] [Indexed: 12/21/2022]
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164
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Ma S, Ma J, Zhou Y, Guo L, Bai J, Zhang M. Tongguan capsule derived-herb ameliorates remodeling at infarcted border zone and reduces ventricular arrhythmias in rats after myocardial infarction. Biomed Pharmacother 2019; 120:109514. [DOI: 10.1016/j.biopha.2019.109514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 09/29/2019] [Accepted: 09/30/2019] [Indexed: 01/24/2023] Open
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165
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Seitz J, Bars C, Gitenay E, Bremondy M, Kalifa J. What Is the Relevance of Low-Voltage Maps to the Underlying Atrial Scar? JACC Clin Electrophysiol 2019; 5:1278-1279. [PMID: 31753432 DOI: 10.1016/j.jacep.2019.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 10/15/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Julien Seitz
- St. Joseph Hospital, Unité de Rythmologie Interventionnelle, Marseille, France.
| | - Clément Bars
- St. Joseph Hospital, Unité de Rythmologie Interventionnelle, Marseille, France
| | - Edouard Gitenay
- St. Joseph Hospital, Unité de Rythmologie Interventionnelle, Marseille, France
| | - Michel Bremondy
- St. Joseph Hospital, Unité de Rythmologie Interventionnelle, Marseille, France
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166
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Pouranbarani E, Weber dos Santos R, Nygren A. A robust multi-objective optimization framework to capture both cellular and intercellular properties in cardiac cellular model tuning: Analyzing different regions of membrane resistance profile in parameter fitting. PLoS One 2019; 14:e0225245. [PMID: 31730631 PMCID: PMC6857942 DOI: 10.1371/journal.pone.0225245] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 10/31/2019] [Indexed: 02/07/2023] Open
Abstract
Mathematical models of cardiac cells have been established to broaden understanding of cardiac function. In the process of developing electrophysiological models for cardiac myocytes, precise parameter tuning is a crucial step. The membrane resistance (Rm) is an essential feature obtained from cardiac myocytes. This feature reflects intercellular coupling and affects important phenomena, such as conduction velocity, and early after-depolarizations, but it is often overlooked during the phase of parameter fitting. Thus, the traditional parameter fitting that only includes action potential (AP) waveform may yield incorrect values for Rm. In this paper, a novel multi-objective parameter fitting formulation is proposed and tested that includes different regions of the Rm profile as additional objective functions for optimization. As Rm depends on the transmembrane voltage (Vm) and exhibits singularities for some specific values of Vm, analyses are conducted to carefully select the regions of interest for the proper characterization of Rm. Non-dominated sorting genetic algorithm II is utilized to solve the proposed multi-objective optimization problem. To verify the efficacy of the proposed problem formulation, case studies and comparisons are carried out using multiple models of human cardiac ventricular cells. Results demonstrate Rm is correctly reproduced by the tuned cell models after considering the curve of Rm obtained from the late phase of repolarization and Rm value calculated in the rest phase as additional objectives. However, relative deterioration of the AP fit is observed, demonstrating trade-off among the objectives. This framework can be useful for a wide range of applications, including the parameters fitting phase of the cardiac cell model development and investigation of normal and pathological scenarios in which reproducing both cellular and intercellular properties are of great importance.
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Affiliation(s)
- Elnaz Pouranbarani
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
| | - Rodrigo Weber dos Santos
- Department of Computer Science and the Graduate Program of Computational Modeling, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Anders Nygren
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
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167
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Rottmann M, Kleber AG, Barkagan M, Sroubek J, Leshem E, Shapira-Daniels A, Buxton AE, Anter E. Activation During Sinus Rhythm in Ventricles With Healed Infarction: Differentiation Between Arrhythmogenic and Nonarrhythmogenic Scar. Circ Arrhythm Electrophysiol 2019; 12:e007879. [PMID: 31597477 DOI: 10.1161/circep.119.007879] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND In infarct-related ventricular tachycardia (VT), the circuit often corresponds to a location characterized by activation slowing during sinus rhythm (SR). However, the relationship between activation slowing during SR and vulnerability for reentry and correlation to components of the VT circuit are unknown. This study examined the relationship between activation slowing during SR and vulnerability for reentry and correlated these areas with components of the circuit. METHODS In a porcine model of healed infarction, the spatial distribution of endocardial activation velocity was compared between SR and VT. Isthmus sites were defined using activation and entrainment mapping as areas exhibiting diastolic activity within the circuit while bystanders were defined as areas displaying diastolic activity outside the circuit. RESULTS Of 15 swine, 9 had inducible VT (5.2±3.0 per animal) while in 6 swine VT could not be induced despite stimulation from 4 RV and LV sites at 2 drive trains with 6 extra-stimuli down to refractoriness. Infarcts with VT had a greater magnitude of activation slowing during SR. A minimal endocardial activation velocity cutoff ≤0.1 m/s differentiated inducible from noninducible infarctions (P=0.015). Regions of maximal endocardial slowing during SR corresponded to the VT isthmus (area under curve=0.84 95% CI, 0.78-0.90) while bystander sites exhibited near-normal activation during SR. VT circuits were complex with 41.7% exhibiting discontinuous propagation with intramural bridges of slow conduction and delayed quasi-simultaneous endocardial activation. Regions forming the VT isthmus borders had faster activation during SR while regions forming the inner isthmus were activated faster during VT. CONCLUSIONS Endocardial activation slowing during SR may differentiate infarctions vulnerable for VT from those less vulnerable for VT. Sites of slow activation during SR correspond to sites forming the VT isthmus but not to bystander sites.
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Affiliation(s)
- Markus Rottmann
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Andre G Kleber
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Michael Barkagan
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Jakub Sroubek
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Eran Leshem
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Ayelet Shapira-Daniels
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Alfred E Buxton
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Elad Anter
- Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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168
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Sengupta S, Rothenberg KE, Li H, Hoffman BD, Bursac N. Altering integrin engagement regulates membrane localization of K ir2.1 channels. J Cell Sci 2019; 132:jcs225383. [PMID: 31391240 PMCID: PMC6771140 DOI: 10.1242/jcs.225383] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 07/31/2019] [Indexed: 12/26/2022] Open
Abstract
How ion channels localize and distribute on the cell membrane remains incompletely understood. We show that interventions that vary cell adhesion proteins and cell size also affect the membrane current density of inward-rectifier K+ channels (Kir2.1; encoded by KCNJ2) and profoundly alter the action potential shape of excitable cells. By using micropatterning to manipulate the localization and size of focal adhesions (FAs) in single HEK293 cells engineered to stably express Kir2.1 channels or in neonatal rat cardiomyocytes, we establish a robust linear correlation between FA coverage and the amplitude of Kir2.1 current at both the local and whole-cell levels. Confocal microscopy showed that Kir2.1 channels accumulate in membrane proximal to FAs. Selective pharmacological inhibition of key mediators of protein trafficking and the spatially dependent alterations in the dynamics of Kir2.1 fluorescent recovery after photobleaching revealed that the Kir2.1 channels are transported to the cell membrane uniformly, but are preferentially internalized by endocytosis at sites that are distal from FAs. Based on these results, we propose adhesion-regulated membrane localization of ion channels as a fundamental mechanism of controlling cellular electrophysiology via mechanochemical signals, independent of the direct ion channel mechanogating.
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Affiliation(s)
- Swarnali Sengupta
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | | | - Hanjun Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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169
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Colli-Franzone P, Gionti V, Pavarino L, Scacchi S, Storti C. Role of infarct scar dimensions, border zone repolarization properties and anisotropy in the origin and maintenance of cardiac reentry. Math Biosci 2019; 315:108228. [DOI: 10.1016/j.mbs.2019.108228] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 07/13/2019] [Accepted: 07/14/2019] [Indexed: 10/26/2022]
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170
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Abstract
Optical mapping of electrical activity in the heart is based on voltage-sensitive and lipophilic fluorescence dyes. Optical signals recorded from cardiac cells correlate well with their transmembrane potentials. High spatiotemporal resolution, wide field mapping, and high sensitivity to transmembrane potential enable detailed characterization of action potential initiation and propagation. Optical mapping is used to study complex patterns of excitation propagation, including propagation across the sinoatrial and atrioventricular nodes and during atrial and ventricular arrhythmias.Optical mapping is used to study the role of reentrant activity in atrial and ventricular fibrillation.
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171
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Pashakhanloo F, Herzka DA, Halperin H, McVeigh ER, Trayanova NA. Role of 3-Dimensional Architecture of Scar and Surviving Tissue in Ventricular Tachycardia: Insights From High-Resolution Ex Vivo Porcine Models. Circ Arrhythm Electrophysiol 2019; 11:e006131. [PMID: 29880529 DOI: 10.1161/circep.117.006131] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 04/05/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND An improved knowledge of the spatial organization of infarct structure and its contribution to ventricular tachycardia (VT) is important for designing optimal treatments. This study explores the relationship between the 3-dimensional structure of the healed infarct and the VT reentrant pathways in high-resolution models of infarcted porcine hearts. METHODS Structurally detailed models of infarcted ventricles were reconstructed from ex vivo late gadolinium enhancement and diffusion tensor magnetic resonance imaging data of 8 chronically infarcted porcine hearts at submillimeter resolution (0.25×0.25×0.5 mm3). To characterize the 3-dimensional structure of surviving tissue in the zone of infarct, a novel scar-mapped thickness metric was introduced. Further, using the ventricular models, electrophysiological simulations were conducted to determine and analyze the 3-dimensional VT pathways that were established in each of the complex infarct morphologies. RESULTS The scar-mapped thickness metric revealed the heterogeneous organization of infarct and enabled us to systematically characterize the distribution of surviving tissue thickness in 8 hearts. Simulation results demonstrated the involvement of a subendocardial tissue layer of varying thickness in the majority of VT pathways. Importantly, they revealed that VT pathways are most frequently established within thin surviving tissue structures of thickness ≤2.2 mm (90th percentile) surrounding the scar. CONCLUSIONS The combination of high-resolution imaging data and ventricular simulations revealed the 3-dimensional distribution of surviving tissue surrounding the scar and demonstrated its involvement in VT pathways. The new knowledge obtained in this study contributes toward a better understanding of infarct-related VT.
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Affiliation(s)
| | - Daniel A Herzka
- Department of Biomedical Engineering (F.P., D.A.H., E.R.M., N.A.T.)
| | | | - Elliot R McVeigh
- Department of Biomedical Engineering (F.P., D.A.H., E.R.M., N.A.T.).,Johns Hopkins University, Baltimore, MD. Departments of Bioengineering, Medicine, and Radiology, University of California, San Diego, La Jolla (E.R.M.)
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172
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Factors Promoting Conduction Slowing as Substrates for Block and Reentry in Infarcted Hearts. Biophys J 2019; 117:2361-2374. [PMID: 31521328 PMCID: PMC6990374 DOI: 10.1016/j.bpj.2019.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/03/2019] [Accepted: 08/05/2019] [Indexed: 01/11/2023] Open
Abstract
The development of effective and safe therapies for scar-related ventricular tachycardias requires a detailed understanding of the mechanisms underlying the conduction block that initiates electrical re-entries associated with these arrhythmias. Conduction block has been often associated with electrophysiological changes that prolong action potential duration (APD) within the border zone (BZ) of chronically infarcted hearts. However, experimental evidence suggests that remodeling processes promoting conduction slowing as opposed to APD prolongation mark the chronic phase. In this context, the substrate for the initial block at the mouth of an isthmus/diastolic channel leading to ventricular tachycardia is unclear. The goal of this study was to determine whether electrophysiological parameters associated with conduction slowing can cause block and re-entry in the BZ. In silico experiments were conducted on two-dimensional idealized infarct tissue as well as on a cohort of postinfarction porcine left ventricular models constructed from ex vivo magnetic resonance imaging scans. Functional conduction slowing in the BZ was modeled by reducing sodium current density, whereas structural conduction slowing was represented by decreasing tissue conductivity and including fibrosis. The arrhythmogenic potential of APD prolongation was also tested as a basis for comparison. Within all models, the combination of reduced sodium current with structural remodeling more often degenerated into re-entry and, if so, was more likely to be sustained for more cycles. Although re-entries were also detected in experiments with prolonged APD, they were often not sustained because of the subsequent block caused by long-lasting repolarization. Functional and structural conditions associated with slow conduction rather than APD prolongation form a potent substrate for arrhythmogenesis at the isthmus/BZ of chronically infarcted hearts. Reduced excitability led to block while slow conduction shortened the wavelength of propagation, facilitating the sustenance of re-entries. These findings provide important insights for models of patient-specific risk stratification and therapy planning.
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173
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Houck PD, Jones B, Patel R, Olsovsky G. Pathophysiology of narrow complex dilated cardiomyopathy insight derived from the velocity equation: velocity = distance/time. BMJ Case Rep 2019; 12:12/8/e229339. [PMID: 31387863 PMCID: PMC6685373 DOI: 10.1136/bcr-2019-229339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The pathophysiology of narrow complex dilated cardiomyopathy is not defined, so therapeutic options are limited. By utilising the velocity equation, the pathophysiology of narrow complex cardiomyopathy allows above normal conduction propagation velocities. There are two pathophysiological theories that allow above normal conduction velocities and failure to capture the myocardium: (1)insulating fibres of the conduction system extending beyond the apex and (2) reduction of axon branching. A patient with narrow complex cardiomyopathy was subjected to graded increase in amplitude and pulse width pacing to overcome the failure of native conduction to capture the myocardium. Peak systolic strain maps demonstrated a progressive increase in apical contractility with increasing pulse width and amplitude. Ejection fraction improved from 17% to 31%. Understanding the pathophysiology of narrow complex cardiomyopathy leads to proposed therapies. One potential pacing therapy is multi-lead pacing at high amplitude and pulse width to capture myocardial cells not captured by native conduction.
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Affiliation(s)
- Philip D Houck
- Department of Medicine Division of Cardiology, Baylor Scott & White Health, Temple, Texas, USA
| | - Billy Jones
- Department of Medicine Division of Cardiology, Baylor Scott & White Health, Temple, Texas, USA
| | - Rikin Patel
- Department of Medicine Division of Cardiology, Baylor Scott & White Health, Temple, Texas, USA
| | - Greg Olsovsky
- Department of Medicine Division of Cardiology, Baylor Scott & White Health, Temple, Texas, USA
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174
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Kim H, Kim MK, Jang H, Kim B, Kim DR, Lee CH. Sensor-Instrumented Scaffold Integrated with Microporous Spongelike Ultrabuoy for Long-Term 3D Mapping of Cellular Behaviors and Functions. ACS NANO 2019; 13:7898-7904. [PMID: 31244034 DOI: 10.1021/acsnano.9b02291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Real-time monitoring of cellular behaviors and functions with sensor-instrumented scaffolds can provide a profound impact on fundamental studies of the underlying biophysics and disease modeling. Although quantitative measurement of predictive data for in vivo tests and physiologically relevant information in these contexts is important, the long-term reliable monitoring of cellular functions in three-dimensional (3D) environments is limited by the required set under wet cell culture conditions that are unfavorable to electronic instrument settings. Here, we introduce an ultrabuoyant 3D instrumented scaffold that can remain afloat on the surface of culture medium and thereby provides favorable environments for the entire electronic components in the air while the cells reside and grow underneath. This setting enables high-fidelity recording of electrical cell-substrate impedance and electrophysiological signals for a long period of time (weeks). Comprehensive in vitro studies reveal the utility of this platform as an effective tool for drug screening and tissue development.
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Affiliation(s)
- Hyungjun Kim
- Weldon School of Biomedical Engineering , Purdue University , 206 South Martin Jischke Drive , West Lafayette , Indiana 47907 , United States
| | - Min Ku Kim
- Weldon School of Biomedical Engineering , Purdue University , 206 South Martin Jischke Drive , West Lafayette , Indiana 47907 , United States
| | - Hanmin Jang
- School of Mechanical Engineering , Hanyang University , 222 Wangsimni-ro , Seongdong-gu, Seoul 04763 , Republic of Korea
| | - Bongjoong Kim
- School of Mechanical Engineering , Purdue University , 610 Purdue Mall , West Lafayette , Indiana 47907 , United States
| | - Dong Rip Kim
- School of Mechanical Engineering , Hanyang University , 222 Wangsimni-ro , Seongdong-gu, Seoul 04763 , Republic of Korea
| | - Chi Hwan Lee
- Weldon School of Biomedical Engineering , Purdue University , 206 South Martin Jischke Drive , West Lafayette , Indiana 47907 , United States
- School of Mechanical Engineering , Purdue University , 610 Purdue Mall , West Lafayette , Indiana 47907 , United States
- Department of Speech, Language, and Hearing Sciences , Purdue University , West Lafayette , Indiana 47907 , United States
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175
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Lee AWC, Nguyen UC, Razeghi O, Gould J, Sidhu BS, Sieniewicz B, Behar J, Mafi-Rad M, Plank G, Prinzen FW, Rinaldi CA, Vernooy K, Niederer S. A rule-based method for predicting the electrical activation of the heart with cardiac resynchronization therapy from non-invasive clinical data. Med Image Anal 2019; 57:197-213. [PMID: 31326854 PMCID: PMC6746621 DOI: 10.1016/j.media.2019.06.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/20/2019] [Accepted: 06/27/2019] [Indexed: 12/13/2022]
Abstract
Background Cardiac Resynchronization Therapy (CRT) is one of the few effective treatments for heart failure patients with ventricular dyssynchrony. The pacing location of the left ventricle is indicated as a determinant of CRT outcome. Objective Patient specific computational models allow the activation pattern following CRT implant to be predicted and this may be used to optimize CRT lead placement. Methods In this study, the effects of heterogeneous cardiac substrate (scar, fast endocardial conduction, slow septal conduction, functional block) on accurately predicting the electrical activation of the LV epicardium were tested to determine the minimal detail required to create a rule based model of cardiac electrophysiology. Non-invasive clinical data (CT or CMR images and 12 lead ECG) from eighteen patients from two centers were used to investigate the models. Results Validation with invasive electro-anatomical mapping data identified that computer models with fast endocardial conduction were able to predict the electrical activation with a mean distance errors of 9.2 ± 0.5 mm (CMR data) or (CT data) 7.5 ± 0.7 mm. Conclusion This study identified a simple rule-based fast endocardial conduction model, built using non-invasive clinical data that can be used to rapidly and robustly predict the electrical activation of the heart. Pre-procedural prediction of the latest electrically activating region to identify the optimal LV pacing site could potentially be a useful clinical planning tool for CRT procedures.
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Affiliation(s)
- A W C Lee
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
| | - U C Nguyen
- Department of Physiology, Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands; Department of Cardiology, Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands
| | - O Razeghi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - J Gould
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - B S Sidhu
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - B Sieniewicz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - J Behar
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Bart's Heart Centre, St. Bartholomew's Hospital, London, United Kingdom
| | - M Mafi-Rad
- Department of Cardiology, Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands
| | - G Plank
- Department of Biophysics, Medical University of Graz, Graz, Austria
| | - F W Prinzen
- Department of Physiology, Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands
| | - C A Rinaldi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - K Vernooy
- Department of Cardiology, Maastricht University Medical Center (MUMC+), Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands; Department of Cardiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - S Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
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176
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A fundamental evaluation of the electrical properties and function of cardiac transverse tubules. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118502. [PMID: 31269418 DOI: 10.1016/j.bbamcr.2019.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/07/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
This work discusses active and passive electrical properties of transverse (T-)tubules in ventricular cardiomyocytes to understand the physiological roles of T-tubules. T-tubules are invaginations of the lateral membrane that provide a large surface for calcium-handling proteins to facilitate sarcomere shortening. Higher heart rates correlate with higher T-tubular densities in mammalian ventricular cardiomyocytes. We assess ion dynamics in T-tubules and the effects of sodium current in T-tubules on the extracellular potential, which leads to a partial reduction of the sodium current in deep segments of a T-tubule. We moreover reflect on the impact of T-tubules on macroscopic conduction velocity, integrating fundamental principles of action potential propagation and conduction. We also theoretically assess how the conduction velocity is affected by different T-tubular sodium current densities. Lastly, we critically assess literature on ion channel expression to determine whether action potentials can be initiated in T-tubules.
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177
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Ma S, Ma J, Mai X, Zhao X, Guo L, Zhang M. Danqi soft capsule prevents infarct border zone remodelling and reduces susceptibility to ventricular arrhythmias in post-myocardial infarction rats. J Cell Mol Med 2019; 23:5454-5465. [PMID: 31232519 PMCID: PMC6653321 DOI: 10.1111/jcmm.14428] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/11/2019] [Accepted: 04/19/2019] [Indexed: 12/15/2022] Open
Abstract
Danqi soft capsule (DQ) is a traditional Chinese medicine containing Salvia miltiorrhiza and Panax notoginseng; it is safe and efficient in treating ischaemic heart diseases. The purpose of the present study was to assess whether DQ could prevent infarct border zone (IBZ) remodelling and decrease ventricular arrhythmias occurrence in post‐myocardial infarction (MI) stage. MI was induced by a ligation of the left anterior descending coronary artery. DQ was administered to the post‐MI rats started from 1 week after MI surgery for 4 weeks. The results showed that DQ treatment significantly attenuated tachyarrhythmia induction rates and arrhythmia score in post‐MI rats. In echocardiography, DQ improved left ventricular (LV) systolic and diastolic function. Histological assessment revealed that DQ significantly reduced fibrotic areas and myocyte areas, and increased connexin (Cx) 43 positive areas in IBZ. Western blot revealed that DQ treatment significantly reduced the protein expression levels of type I and III collagens, α‐smooth muscle actin (α‐SMA), transforming growth factor‐β1 (TGF‐β1) and Smad3 phosphorylation, while increasing Cx43 amounts. Overall, these findings mainly indicated that DQ intervention regulates interstitial fibrosis, Cx43 expression and myocyte hypertrophy by TGF‐β1/Smad3 pathway in IBZ, inhibits LV remodelling and reduces vulnerability to tachyarrhythmias after MI. This study presents a proof of concept for novel antiarrhythmic strategies in preventing IBZ remodelling, modifying the healed arrhythmogenic substrate and thus reducing susceptibility to ventricular arrhythmias in the late post‐MI period.
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Affiliation(s)
- Shiyu Ma
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,Guangzhou Key Laboratory of Chinese Medicine for Prevention and Treatment of Myocardial Infarction, Guangzhou, China
| | - Jin Ma
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Xiaoyi Mai
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,Guangzhou Key Laboratory of Chinese Medicine for Prevention and Treatment of Myocardial Infarction, Guangzhou, China
| | - Xujie Zhao
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Liheng Guo
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Minzhou Zhang
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,Guangzhou Key Laboratory of Chinese Medicine for Prevention and Treatment of Myocardial Infarction, Guangzhou, China
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178
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Sasse P, Funken M, Beiert T, Bruegmann T. Optogenetic Termination of Cardiac Arrhythmia: Mechanistic Enlightenment and Therapeutic Application? Front Physiol 2019; 10:675. [PMID: 31244670 PMCID: PMC6563676 DOI: 10.3389/fphys.2019.00675] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
Optogenetic methods enable selective de- and hyperpolarization of cardiomyocytes expressing light-sensitive proteins within the myocardium. By using light, this technology provides very high spatial and temporal precision, which is in clear contrast to electrical stimulation. In addition, cardiomyocyte-specific expression would allow pain-free stimulation. In light of these intrinsic technical advantages, optogenetic methods provide an intriguing opportunity to understand and improve current strategies to terminate cardiac arrhythmia as well as for possible pain-free arrhythmia termination in patients in the future. In this review, we give a concise introduction to optogenetic stimulation of cardiomyocytes and the whole heart and summarize the recent progress on optogenetic defibrillation and cardioversion to terminate cardiac arrhythmia. Toward this aim, we specifically focus on the different mechanisms of optogenetic arrhythmia termination and how these might influence the prerequisites for success. Furthermore, we critically discuss the clinical perspectives and potential patient populations, which might benefit from optogenetic defibrillation devices.
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Affiliation(s)
- Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Maximilian Funken
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Department of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Thomas Beiert
- Department of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Research Training Group 1873, University of Bonn, Bonn, Germany.,Institute of Cardiovascular Physiology, University Medical Center, Georg August University Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK), Partner site Göttingen, Göttingen, Germany
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179
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Salvarani N, Crasto S, Miragoli M, Bertero A, Paulis M, Kunderfranco P, Serio S, Forni A, Lucarelli C, Dal Ferro M, Larcher V, Sinagra G, Vezzoni P, Murry CE, Faggian G, Condorelli G, Di Pasquale E. The K219T-Lamin mutation induces conduction defects through epigenetic inhibition of SCN5A in human cardiac laminopathy. Nat Commun 2019; 10:2267. [PMID: 31118417 PMCID: PMC6531493 DOI: 10.1038/s41467-019-09929-w] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 04/06/2019] [Indexed: 12/14/2022] Open
Abstract
Mutations in LMNA, which encodes the nuclear proteins Lamin A/C, can cause cardiomyopathy and conduction disorders. Here, we employ induced pluripotent stem cells (iPSCs) generated from human cells carrying heterozygous K219T mutation on LMNA to develop a disease model. Cardiomyocytes differentiated from these iPSCs, and which thus carry K219T-LMNA, have altered action potential, reduced peak sodium current and diminished conduction velocity. Moreover, they have significantly downregulated Nav1.5 channel expression and increased binding of Lamin A/C to the promoter of SCN5A, the channel's gene. Coherently, binding of the Polycomb Repressive Complex 2 (PRC2) protein SUZ12 and deposition of the repressive histone mark H3K27me3 are increased at SCN5A. CRISPR/Cas9-mediated correction of the mutation re-establishes sodium current density and SCN5A expression. Thus, K219T-LMNA cooperates with PRC2 in downregulating SCN5A, leading to decreased sodium current density and slower conduction velocity. This mechanism may underlie the conduction abnormalities associated with LMNA-cardiomyopathy.
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Affiliation(s)
- Nicolò Salvarani
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Silvia Crasto
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Michele Miragoli
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
- Department of Medicine and Surgery, University of Parma, Parma, 43121, Italy
| | - Alessandro Bertero
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, 98109, WA, USA
| | - Marianna Paulis
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Paolo Kunderfranco
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Simone Serio
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Alberto Forni
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Carla Lucarelli
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Matteo Dal Ferro
- Cardiovascular Department, "Ospedali Riuniti" and University of Trieste, Trieste, 34129, Italy
| | - Veronica Larcher
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Gianfranco Sinagra
- Cardiovascular Department, "Ospedali Riuniti" and University of Trieste, Trieste, 34129, Italy
| | - Paolo Vezzoni
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy
| | - Charles E Murry
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, 98109, WA, USA
| | - Giuseppe Faggian
- Division of Cardiac Surgery, University of Verona, Verona, 37129, Italy
| | - Gianluigi Condorelli
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy.
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy.
- Humanitas University, Rozzano (MI), 20089, Italy.
| | - Elisa Di Pasquale
- Institute of Genetic and Biomedical Research (IRGB), UOS of Milan, National Research Council of Italy, Milan, 20138, Italy.
- Department of Cardiovascular Medicine and Laboratory of Medical Biotechnology, Humanitas Clinical and Research Center - IRCCS, Rozzano (MI), 20089, Italy.
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180
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Left atrial voltage mapping: defining and targeting the atrial fibrillation substrate. J Interv Card Electrophysiol 2019; 56:213-227. [PMID: 31076965 PMCID: PMC6900285 DOI: 10.1007/s10840-019-00537-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 03/12/2019] [Indexed: 12/23/2022]
Abstract
Low atrial endocardial bipolar voltage, measured during catheter ablation for atrial fibrillation (AF), is a commonly used surrogate marker for the presence of atrial fibrosis. Low voltage shows many useful associations with clinical outcomes, comorbidities and has links to trigger sites for AF. Several contemporary trials have shown promise in targeting low voltage areas as the substrate for AF ablation; however, the results have been mixed. In order to understand these results, a thorough understanding of voltage mapping techniques, the relationship between low voltage and the pathophysiology of AF, as well as the inherent limitations in voltage measurement are needed. Two key questions must be answered in order to optimally apply voltage mapping as the road map for ablation. First, are the inherent limitations of voltage mapping small enough as to be ignored when targeting specific tissue based on voltage? Second, can conventional criteria, using a binary threshold for voltage amplitude, truly define the extent of the atrial fibrotic substrate? Here, we review the latest clinical evidence with regard to voltage-based ablation procedures before analysing the utility and limitations of voltage mapping. Finally, we discuss omnipole mapping and dynamic voltage attenuation as two possible approaches to resolving these issues.
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181
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Cronin EM, Bogun FM, Maury P, Peichl P, Chen M, Namboodiri N, Aguinaga L, Leite LR, Al-Khatib SM, Anter E, Berruezo A, Callans DJ, Chung MK, Cuculich P, d'Avila A, Deal BJ, Della Bella P, Deneke T, Dickfeld TM, Hadid C, Haqqani HM, Kay GN, Latchamsetty R, Marchlinski F, Miller JM, Nogami A, Patel AR, Pathak RK, Saenz Morales LC, Santangeli P, Sapp JL, Sarkozy A, Soejima K, Stevenson WG, Tedrow UB, Tzou WS, Varma N, Zeppenfeld K. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias. Heart Rhythm 2019; 17:e2-e154. [PMID: 31085023 PMCID: PMC8453449 DOI: 10.1016/j.hrthm.2019.03.002] [Citation(s) in RCA: 186] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Indexed: 01/10/2023]
Abstract
Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.
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Affiliation(s)
| | | | | | - Petr Peichl
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Minglong Chen
- Jiangsu Province Hospital, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Narayanan Namboodiri
- Sree Chitra Institute for Medical Sciences and Technology, Thiruvananthapuram, India
| | | | | | | | - Elad Anter
- Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | | | | | | | | | - Andre d'Avila
- Hospital Cardiologico SOS Cardio, Florianopolis, Brazil
| | - Barbara J Deal
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | | | | | | | - Claudio Hadid
- Hospital General de Agudos Cosme Argerich, Buenos Aires, Argentina
| | - Haris M Haqqani
- University of Queensland, The Prince Charles Hospital, Chermside, Australia
| | - G Neal Kay
- University of Alabama at Birmingham, Birmingham, Alabama
| | | | | | - John M Miller
- Indiana University School of Medicine, Krannert Institute of Cardiology, Indianapolis, Indiana
| | | | - Akash R Patel
- University of California San Francisco Benioff Children's Hospital, San Francisco, California
| | | | | | | | - John L Sapp
- Queen Elizabeth II Health Sciences Centre, Halifax, Canada
| | - Andrea Sarkozy
- University Hospital Antwerp, University of Antwerp, Antwerp, Belgium
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182
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Hendon CP, Lye TH, Yao X, Gan Y, Marboe CC. Optical coherence tomography imaging of cardiac substrates. Quant Imaging Med Surg 2019; 9:882-904. [PMID: 31281782 PMCID: PMC6571187 DOI: 10.21037/qims.2019.05.09] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 05/06/2019] [Indexed: 01/02/2023]
Abstract
Cardiovascular disease is the leading cause of morbidity and mortality in the United States. Knowledge of a patient's heart structure will help to plan procedures, potentially identifying arrhythmia substrates, critical structures to avoid, detect transplant rejection, and reduce ambiguity when interpreting electrograms and functional measurements. Similarly, basic research of numerous cardiac diseases would greatly benefit from structural imaging at cellular scale. For both applications imaging on the scale of a myocyte is needed, which is approximately 100 µm × 10 µm. The use of optical coherence tomography (OCT) as a tool for characterizing cardiac tissue structure and function has been growing in the past two decades. We briefly review OCT principles and highlight important considerations when imaging cardiac muscle. In particular, image penetration, tissue birefringence, and light absorption by blood during in vivo imaging are important factors when imaging the heart with OCT. Within the article, we highlight applications of cardiac OCT imaging including imaging heart tissue structure in small animal models, quantification of myofiber organization, monitoring of radiofrequency ablation (RFA) lesion formation, structure-function analysis enabled by functional extensions of OCT and multimodal analysis and characterizing important substrates within the human heart. The review concludes with a summary and future outlook of OCT imaging the heart, which is promising with progress in optical catheter development, functional extensions of OCT, and real time image processing to enable dynamic imaging and real time tracking during therapeutic procedures.
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Affiliation(s)
| | | | | | - Yu Gan
- Columbia University, New York, NY, USA
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183
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Connolly A, Williams S, Rhode K, Rinaldi CA, Bishop MJ. Conceptual Intra-Cardiac Electrode Configurations That Facilitate Directional Cardiac Stimulation for Optimal Electrotherapy. IEEE Trans Biomed Eng 2019; 66:1259-1268. [PMID: 31021745 PMCID: PMC7054045 DOI: 10.1109/tbme.2018.2871863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Electrotherapy remains the most effective direct therapy against lethal cardiac arrhythmias. When an arrhythmic event is sensed, either strong electric shocks or controlled rapid pacing is automatically applied directly to the heart via an implanted cardioverter defibrillator (ICDs). Despite their success, ICDs remain a highly non-optimal therapy: the strong shocks required for defibrillation cause significant extra-cardiac stimulation, resulting in pain and long-term tissue damage, and can also limit battery life. When used in anti-tachycardia pacing mode, ICDs are also often ineffective, as the pacing electrode can be far away from the centre of the arrhythmia, making it hard for the paced wave to interrupt and terminate it. METHODS In this paper, we present two conceptual intra-cardiac directional electrode configurations in silico based on novel arrangements of pairs of positive-negative electrodes. Both configurations have the potential to cause preferential excitation on specific regions of the heart. RESULTS We demonstrate how the properties of the induced field varies spatially around the electrodes and how it depends upon the specific arrangements of dipole electrode pairs. The results show that when tested within anatomically-realistic rabbit ventricular models, both electrode configurations produce strong virtual electrodes on the targeted endocardial surfaces, with weaker virtual electrodes produced elsewhere. CONCLUSIONS The proposed electrode configurations may facilitate targeted far-field anti-tachycardia pacing and/or defibrillation, which may be useful in cases where conventional anti-tachycardia pacing fails. In addition, the conceptual electrode designs intrinsically confine the electric field to the immediate vicinity of the electrodes, and may, thus, minimize pain due to unnecessary extra-cardiac stimulation.
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184
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Campos FO, Orini M, Taggart P, Hanson B, Lambiase PD, Porter B, Rinaldi CA, Gill J, Bishop MJ. Characterizing the clinical implementation of a novel activation-repolarization metric to identify targets for catheter ablation of ventricular tachycardias using computational models. Comput Biol Med 2019; 108:263-275. [PMID: 31009930 PMCID: PMC6538827 DOI: 10.1016/j.compbiomed.2019.03.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/08/2019] [Accepted: 03/19/2019] [Indexed: 11/24/2022]
Abstract
Identification of targets for catheter ablation of ventricular tachycardias (VTs) remains a significant challenge. VTs are often driven by re-entrant circuits resulting from a complex interaction between the front (activation) and tail (repolarization) of the electrical wavefront. Most mapping techniques do not take into account the tissue repolarization which may hinder the detection of ablation targets. The re-entry vulnerability index (RVI), a recently proposed mapping procedure, incorporates both activation and repolarization times to uncover VT circuits. The method showed potential in a series of experiments, but it still requires further development to enable its incorporation into a clinical protocol. Here, in-silico experiments were conducted to thoroughly assess RVI maps constructed under clinically-relevant mapping conditions. Within idealized as well as anatomically realistic infarct models, we show that parameters of the algorithm such as the search radius can significantly alter the specificity and sensitivity of the RVI maps. When constructed on sparse grids obtained following various placements of clinical recording catheters, RVI maps can identify vulnerable regions as long as two electrodes were placed on both sides of the line of block. Moreover, maps computed during pacing without inducing VT can reveal areas of abnormal repolarization and slow conduction but not directly vulnerability. In conclusion, the RVI algorithm can detect re-entrant circuits during VT from low resolution mapping grids resembling the clinical setting. Furthermore, RVI maps may provide information about the underlying tissue electrophysiology to guide catheter ablation without the need of inducing potentially harmful VT during the clinical procedure. Finally, the ability of the RVI maps to identify vulnerable regions with specificity in high resolution computer models could potentially improve the prediction of optimal ablation targets of simulation-based strategies. Safe and accurate detection of targets for catheter ablation remains a challenge. We conducted a thorough assessment of the Re-entry Vulnerability Index (RVI). Parameters of the algorithm can alter the specificity and sensitivity of RVI maps. When constructed on sparse grids RVI maps could still detect arrhythmogenic sites. In absence of arrhythmia, RVI maps revealed abnormal sites, but not vulnerability.
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Affiliation(s)
- Fernando O Campos
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Michele Orini
- The Heart Hospital, University College London, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Peter Taggart
- The Heart Hospital, University College London, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, United Kingdom; Electrophysiology Department, Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom
| | - Bradley Porter
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Department of Cardiology, Guys and St Thomas' NHS Trust, London, United Kingdom
| | | | - Jaswinder Gill
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Department of Cardiology, Guys and St Thomas' NHS Trust, London, United Kingdom
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom. https://kclpure.kcl.ac.uk/portal/martin.bishop.html
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185
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Kudryashova N, Nizamieva A, Tsvelaya V, Panfilov AV, Agladze KI. Self-organization of conducting pathways explains electrical wave propagation in cardiac tissues with high fraction of non-conducting cells. PLoS Comput Biol 2019; 15:e1006597. [PMID: 30883540 PMCID: PMC6438583 DOI: 10.1371/journal.pcbi.1006597] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 03/28/2019] [Accepted: 02/04/2019] [Indexed: 02/04/2023] Open
Abstract
Cardiac fibrosis occurs in many forms of heart disease and is considered to be one of the main arrhythmogenic factors. Regions with a high density of fibroblasts are likely to cause blocks of wave propagation that give rise to dangerous cardiac arrhythmias. Therefore, studies of the wave propagation through these regions are very important, yet the precise mechanisms leading to arrhythmia formation in fibrotic cardiac tissue remain poorly understood. Particularly, it is not clear how wave propagation is organized at the cellular level, as experiments show that the regions with a high percentage of fibroblasts (65-75%) are still conducting electrical signals, whereas geometric analysis of randomly distributed conducting and non-conducting cells predicts connectivity loss at 40% at the most (percolation threshold). To address this question, we used a joint in vitro-in silico approach, which combined experiments in neonatal rat cardiac monolayers with morphological and electrophysiological computer simulations. We have shown that the main reason for sustainable wave propagation in highly fibrotic samples is the formation of a branching network of cardiomyocytes. We have successfully reproduced the morphology of conductive pathways in computer modelling, assuming that cardiomyocytes align their cytoskeletons to fuse into cardiac syncytium. The electrophysiological properties of the monolayers, such as conduction velocity, conduction blocks and wave fractionation, were reproduced as well. In a virtual cardiac tissue, we have also examined the wave propagation at the subcellular level, detected wavebreaks formation and its relation to the structure of fibrosis and, thus, analysed the processes leading to the onset of arrhythmias. Cardiac arrhythmias are one of the major causes of death in the industrialized world. The most dangerous ones are often caused by the blocks of propagation of electrical signals. One of the common factors that contribute to the likelihood of these blocks, is a condition called cardiac fibrosis. In fibrosis, excitable cardiac tissue is partially replaced with the inexcitable and non-conducting connective tissue. The precise mechanisms leading to arrhythmia formation in fibrotic cardiac tissue remain poorly understood. Therefore, it is important to study wave propagation in fibrosis from cellular to tissue level. In this paper, we study tissues with high densities of non-conducting cells in experiments and computer simulations. We have observed a paradoxical ability of the tissue with extremely high portion of non-conducting cells (up to 75%) to conduct electrical signals and contract synchronously, whereas geometric analysis of randomly distributed cells predicted connectivity loss at 40% at the most. To explain this phenomenon, we have studied the patterns that cardiac cells form in the tissue and reproduced their self-organisation in a computer model. Our virtual model also took into account the polygonal shapes of the spreading cells and explained high arrhythmogenicity of fibrotic tissue.
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Affiliation(s)
- Nina Kudryashova
- Laboratory of Biophysics of Excitable Systems, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Aygul Nizamieva
- Laboratory of Biophysics of Excitable Systems, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Valeriya Tsvelaya
- Laboratory of Biophysics of Excitable Systems, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Alexander V. Panfilov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
- Laboratory of Computational Biology and Medicine, Ural Federal University, Ekaterinburg, Russia
| | - Konstantin I. Agladze
- Laboratory of Biophysics of Excitable Systems, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- * E-mail:
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186
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Slotvitsky M, Tsvelaya V, Frolova S, Dementyeva E, Agladze K. Arrhythmogenicity Test Based on a Human-Induced Pluripotent Stem Cell (iPSC)-Derived Cardiomyocyte Layer. Toxicol Sci 2019; 168:70-77. [PMID: 30388253 DOI: 10.1093/toxsci/kfy274] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In vitro screening for potential side effects of drugs on human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) is a cutting-edge technology in pharmaceutical industry. International groups are currently considering using iPSC-CM as a part of comprehensive battery for an accurate and complex mechanistic-based assessment of the proarrhythmic potential of drugs. Despite iPSC-CMs expression and phenotype differences from mature adult CMs screening for drug-induced prolonged QT interval is now routinely carried and also recommended by ICH. The revelation of the mechanism of how the elongation of the QT interval is associated with the occurrence of an arrhythmia should extend the prospects of screening. To address this problem, a comprehensive tissue-based test for arrhythmogenicity is needed. Induced pluripotent stem (iPS) cells from a healthy individual were differentiated into a CM monolayer that was identified by immunocytochemistry and the patch-clamp technique also considering of the potential impact of the developing phenotype of the iPSC-CMs. To study the occurrence of reentry as a precursor to arrhythmias, a standard obstacle was created in the cell layer. With the aid of optical mapping, the measure of arrhythmogenicity was determined, as defined by the probability of a reentry occurrence for the particular frequency of stimulation. A change in the potassium current corresponding to LQTS type 2 at frequencies matching high heart rates was demonstrated visually and quantitatively. Also, the efficiency of this method for quantifying both the effectiveness and ineffectiveness of drugs for a particular donor and for determining the donor's cardiovascular disease risk zone was tested.
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Affiliation(s)
- Mihail Slotvitsky
- Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
| | - Valeria Tsvelaya
- Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
| | - Sheida Frolova
- Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
| | - Elena Dementyeva
- Institute of Cytology and Genetics.,Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.,Meshalkin National Medical Research Center, Ministry of Health of Russian Federation, Novosibirsk, Russia
| | - Konstantin Agladze
- Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
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187
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Bertuoli P, Ordoño J, Armelin E, Pérez-Amodio S, Baldissera AF, Ferreira CA, Puiggalí J, Engel E, del Valle LJ, Alemán C. Electrospun Conducting and Biocompatible Uniaxial and Core-Shell Fibers Having Poly(lactic acid), Poly(ethylene glycol), and Polyaniline for Cardiac Tissue Engineering. ACS OMEGA 2019; 4:3660-3672. [PMID: 31459579 PMCID: PMC6648110 DOI: 10.1021/acsomega.8b03411] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 01/30/2019] [Indexed: 06/10/2023]
Abstract
Electroactive and biocompatible fibrous scaffolds have been prepared and characterized using polyaniline (PAni) doped with dodecylbenzenesulfonic acid (DBSA) combined with poly(lactic acid) (PLA) and PLA/poly(ethylene glycol) (PEG) mixtures. The composition of simple and core-shell fibers, which have been obtained by both uniaxial and coaxial electrospinning, respectively, has been corroborated by Fourier-transform infrared and micro-Raman spectroscopies. Morphological studies suggest that the incorporation of PEG enhances the packing of PLA and PAni chains, allowing the regulation of the thickness of the fibers. PAni and PEG affect the thermal and electrical properties of the fibers, both decreasing the glass transition temperature and increasing the electrical conductivity. Interestingly, the incorporation of PEG improves the PAni-containing paths associated with the conduction properties. Although dose response curves evidence the high cytotoxicity of PAni/DBSA, cell adhesion and cell proliferation studies on PLA/PAni fibers show a reduction of such harmful effects as the conducting polymer is mainly retained inside the fibers through favorable PAni···PLA interactions. The incorporation of PEG into uniaxial fibers resulted in an increment of the cell mortality, which has been attributed to its rapid dissolution into the culture medium and the consequent enhancement of PAni release. In opposition, the delivery of PAni decreases and, therefore, the biocompatibility of the fibers increases when a shell coating the PAni-containing system is incorporated through coaxial electrospinning. Finally, morphological and functional studies using cardiac cells indicated that these fibrous scaffolds are suitable for cardiac tissue engineering applications.
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Affiliation(s)
- Paula
T. Bertuoli
- Programa
de Pós-Graduação em Engenharia de Minas,
Metalúrgica e Materiais (PPGE3M), and Departamento de Materiais (DEMAT), Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves,
9500, 91501-970 Porto Alegre, Rio Grande do Sul, Brazil
- Departament
d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
- Barcelona
Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, 08019 Barcelona, Spain
| | - Jesús Ordoño
- Institute
for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, 08028 Barcelona, Spain
- CIBER
en Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza 50018, Spain
| | - Elaine Armelin
- Departament
d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
- Barcelona
Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, 08019 Barcelona, Spain
| | - Soledad Pérez-Amodio
- Institute
for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, 08028 Barcelona, Spain
- CIBER
en Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza 50018, Spain
- Materials
Science and Metallurgical Engineering, EEBE, Universitat Politècnica de Catalunya (UPC), C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
| | - Alessandra F. Baldissera
- Programa
de Pós-Graduação em Engenharia de Minas,
Metalúrgica e Materiais (PPGE3M), and Departamento de Materiais (DEMAT), Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves,
9500, 91501-970 Porto Alegre, Rio Grande do Sul, Brazil
| | - Carlos. A. Ferreira
- Programa
de Pós-Graduação em Engenharia de Minas,
Metalúrgica e Materiais (PPGE3M), and Departamento de Materiais (DEMAT), Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves,
9500, 91501-970 Porto Alegre, Rio Grande do Sul, Brazil
| | - Jordi Puiggalí
- Departament
d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
- Barcelona
Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, 08019 Barcelona, Spain
| | - Elisabeth Engel
- Institute
for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, 08028 Barcelona, Spain
- CIBER
en Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza 50018, Spain
- Materials
Science and Metallurgical Engineering, EEBE, Universitat Politècnica de Catalunya (UPC), C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
| | - Luis J. del Valle
- Departament
d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
- Barcelona
Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, 08019 Barcelona, Spain
| | - Carlos Alemán
- Departament
d’Enginyeria Química, EEBE, Universitat Politècnica de Catalunya, C/Eduard Maristany, 10-14, Ed. I2, 08019 Barcelona, Spain
- Barcelona
Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Eduard Maristany, 10-14, 08019 Barcelona, Spain
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188
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Imboden M, de Coulon E, Poulin A, Dellenbach C, Rosset S, Shea H, Rohr S. High-speed mechano-active multielectrode array for investigating rapid stretch effects on cardiac tissue. Nat Commun 2019; 10:834. [PMID: 30783104 PMCID: PMC6381132 DOI: 10.1038/s41467-019-08757-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 01/24/2019] [Indexed: 11/25/2022] Open
Abstract
Systematic investigations of the effects of mechano-electric coupling (MEC) on cellular cardiac electrophysiology lack experimental systems suitable to subject tissues to in-vivo like strain patterns while simultaneously reporting changes in electrical activation. Here, we describe a self-contained motor-less device (mechano-active multielectrode-array, MaMEA) that permits the assessment of impulse conduction along bioengineered strands of cardiac tissue in response to dynamic strain cycles. The device is based on polydimethylsiloxane (PDMS) cell culture substrates patterned with dielectric actuators (DEAs) and compliant gold ion-implanted extracellular electrodes. The DEAs induce uniaxial stretch and compression in defined regions of the PDMS substrate at selectable amplitudes and with rates up to 18 s−1. Conduction along cardiomyocyte strands was found to depend linearly on static strain according to cable theory while, unexpectedly, being completely independent on strain rates. Parallel operation of multiple MaMEAs provides for systematic high-throughput investigations of MEC during spatially patterned mechanical perturbations mimicking in-vivo conditions. While strain is known to affect cardiac electrophysiology, experimental systems to interrogate the effect of rapid strain cycles on cardiac tissue are lacking. Here the authors introduce a multielectrode array that can induce rapid dynamic strain cycles on cardiomyocyte strands and see effects of strain amplitude but not strain rate on impulse conduction.
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Affiliation(s)
- Matthias Imboden
- Soft Transducers Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), 2002, Neuchâtel, Switzerland. .,Department of Physiology, University of Bern, Bühlplatz 5, 3012, Bern, Switzerland.
| | - Etienne de Coulon
- Department of Physiology, University of Bern, Bühlplatz 5, 3012, Bern, Switzerland
| | - Alexandre Poulin
- Soft Transducers Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), 2002, Neuchâtel, Switzerland
| | - Christian Dellenbach
- Department of Physiology, University of Bern, Bühlplatz 5, 3012, Bern, Switzerland
| | - Samuel Rosset
- Soft Transducers Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), 2002, Neuchâtel, Switzerland
| | - Herbert Shea
- Soft Transducers Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), 2002, Neuchâtel, Switzerland
| | - Stephan Rohr
- Department of Physiology, University of Bern, Bühlplatz 5, 3012, Bern, Switzerland.
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189
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Pan Z, Ai T, Chang PC, Liu Y, Liu J, Maruyama M, Homsi M, Fishbein MC, Rubart M, Lin SF, Xiao D, Chen H, Chen PS, Shou W, Li BY. Atrial fibrillation and electrophysiology in transgenic mice with cardiac-restricted overexpression of FKBP12. Am J Physiol Heart Circ Physiol 2019; 316:H371-H379. [PMID: 30499712 PMCID: PMC6397388 DOI: 10.1152/ajpheart.00486.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 11/19/2018] [Accepted: 11/19/2018] [Indexed: 12/19/2022]
Abstract
Cardiomyocyte-restricted overexpression of FK506-binding protein 12 transgenic (αMyHC-FKBP12) mice develop spontaneous atrial fibrillation (AF). The aim of the present study is to explore the mechanisms underlying the occurrence of AF in αMyHC-FKBP12 mice. Spontaneous AF was documented by telemetry in vivo and Langendorff-perfused hearts of αMyHC-FKBP12 and littermate control mice in vitro. Atrial conduction velocity was evaluated by optical mapping. The patch-clamp technique was applied to determine the potentially altered electrophysiology in atrial myocytes. Channel protein expression levels were evaluated by Western blot analyses. Spontaneous AF was recorded in four of seven αMyHC-FKBP12 mice but in none of eight nontransgenic (NTG) controls. Atrial conduction velocity was significantly reduced in αMyHC-FKBP12 hearts compared with NTG hearts. Interestingly, the mean action potential duration at 50% but not 90% was significantly prolonged in αMyHC-FKBP12 atrial myocytes compared with their NTG counterparts. Consistent with decreased conduction velocity, average peak Na+ current ( INa) density was dramatically reduced and the INa inactivation curve was shifted by approximately +7 mV in αMyHC-FKBP12 atrial myocytes, whereas the activation and recovery curves were unaltered. The Nav1.5 expression level was significantly reduced in αMyHC-FKBP12 atria. Furthermore, we found increases in atrial Cav1.2 protein levels and peak L-type Ca2+ current density and increased levels of fibrosis in αMyHC-FKBP12 atria. In summary, cardiomyocyte-restricted overexpression of FKBP12 reduces the atrial Nav1.5 expression level and mean peak INa, which is associated with increased peak L-type Ca2+ current and interstitial fibrosis in atria. The combined electrophysiological and structural changes facilitated the development of local conduction block and altered action potential duration and spontaneous AF. NEW & NOTEWORTHY This study addresses a long-standing riddle regarding the role of FK506-binding protein 12 in cardiac physiology. The work provides further evidence that FK506-binding protein 12 is a critical component for regulating voltage-gated sodium current and in so doing has an important role in arrhythmogenic physiology, such as atrial fibrillation.
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Affiliation(s)
- Zhenwei Pan
- Department of Pharmacology, Harbin Medical University, Heilonjiang, China
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Tomohiko Ai
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Po-Cheng Chang
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
- The Second Section of Cardiology, Departments of Medicine, Chang Gung Memorial Hospital and Chang Gung University School of Medicine , Taoyuan , Taiwan
| | - Ying Liu
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
| | - Jijia Liu
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
- The Second Xiangya Hospital, South Central University School of Medicine , China
| | - Mitsunori Maruyama
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Mohamed Homsi
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Michael C Fishbein
- Department of Pathology and Laboratory Medicine, University of California , Los Angeles, California
| | - Michael Rubart
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
| | - Shien-Fong Lin
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Deyong Xiao
- Fountain Valley Biotechnology, Inc., Dalian Hi-Tech District, Dalian , China
| | - Hanying Chen
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
| | - Peng-Sheng Chen
- Krannert Institute for Cardiology and the Division of Cardiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Weinian Shou
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
| | - Bai-Yan Li
- Department of Pharmacology, Harbin Medical University, Heilonjiang, China
- Wells Center for Pediatric Research, Indiana University School of Medicine , Indianapolis, Indiana
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190
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Dallet C, Roney C, Martin R, Kitamura T, Puyo S, Duchateau J, Dumas-Pomier C, Ravon G, Bear L, Derval N, Sacher F, Vigmond E, Haissaguerre M, Hocini M, Dubois R. Cardiac Propagation Pattern Mapping With Vector Field for Helping Tachyarrhythmias Diagnosis With Clinical Tridimensional Electro-Anatomical Mapping Tools. IEEE Trans Biomed Eng 2019; 66:373-382. [DOI: 10.1109/tbme.2018.2841340] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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191
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A Mathematical Model of the Human Cardiac Na + Channel. J Membr Biol 2019; 252:77-103. [PMID: 30637460 DOI: 10.1007/s00232-018-00058-x] [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: 08/11/2018] [Accepted: 12/31/2018] [Indexed: 01/07/2023]
Abstract
Sodium ion channel is a membrane protein that plays an important role in excitable cells, as it is responsible for the initiation of action potentials. Understanding the electrical characteristics of sodium channels is essential in predicting their behavior under different physiological conditions. We investigated several Markov models for the human cardiac sodium channel NaV1.5 to derive a minimal mathematical model that describes the reported experimental data obtained using major voltage clamp protocols. We obtained simulation results for peak current-voltage relationships, the voltage dependence of normalized ion channel conductance, steady-state inactivation, activation and deactivation kinetics, fast and slow inactivation kinetics, and recovery from inactivation kinetics. Good agreement with the experimental data provides us with the mechanisms of the fast and slow inactivation of the human sodium channel and the coupling of its inactivation states to the closed and open states in the activation pathway.
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192
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Cantwell CD, Mohamied Y, Tzortzis KN, Garasto S, Houston C, Chowdhury RA, Ng FS, Bharath AA, Peters NS. Rethinking multiscale cardiac electrophysiology with machine learning and predictive modelling. Comput Biol Med 2019; 104:339-351. [PMID: 30442428 PMCID: PMC6334203 DOI: 10.1016/j.compbiomed.2018.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/04/2018] [Accepted: 10/14/2018] [Indexed: 11/17/2022]
Abstract
We review some of the latest approaches to analysing cardiac electrophysiology data using machine learning and predictive modelling. Cardiac arrhythmias, particularly atrial fibrillation, are a major global healthcare challenge. Treatment is often through catheter ablation, which involves the targeted localised destruction of regions of the myocardium responsible for initiating or perpetuating the arrhythmia. Ablation targets are either anatomically defined, or identified based on their functional properties as determined through the analysis of contact intracardiac electrograms acquired with increasing spatial density by modern electroanatomic mapping systems. While numerous quantitative approaches have been investigated over the past decades for identifying these critical curative sites, few have provided a reliable and reproducible advance in success rates. Machine learning techniques, including recent deep-learning approaches, offer a potential route to gaining new insight from this wealth of highly complex spatio-temporal information that existing methods struggle to analyse. Coupled with predictive modelling, these techniques offer exciting opportunities to advance the field and produce more accurate diagnoses and robust personalised treatment. We outline some of these methods and illustrate their use in making predictions from the contact electrogram and augmenting predictive modelling tools, both by more rapidly predicting future states of the system and by inferring the parameters of these models from experimental observations.
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Affiliation(s)
- Chris D Cantwell
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; Department of Aeronautics, Imperial College London, South Kensington Campus, London, UK.
| | - Yumnah Mohamied
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
| | - Konstantinos N Tzortzis
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
| | - Stef Garasto
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, South Kensington Campus, London, UK
| | - Charles Houston
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
| | - Rasheda A Chowdhury
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
| | - Fu Siong Ng
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
| | - Anil A Bharath
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; Department of Bioengineering, Imperial College London, South Kensington Campus, London, UK
| | - Nicholas S Peters
- ElectroCardioMaths Group, Imperial College Centre for Cardiac Engineering, Imperial College London, London, UK; National Heart and Lung Institute, Imperial College London, South Kensington Campus, London, UK
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193
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Nayyar S, Downar E, Beheshti M, Liang T, Massé S, Magtibay K, Bhaskaran A, Saeed Y, Vigmond E, Nanthakumar K. Information theory to tachycardia therapy: electrogram entropy predicts diastolic microstructure of reentrant ventricular tachycardia. Am J Physiol Heart Circ Physiol 2019; 316:H134-H144. [DOI: 10.1152/ajpheart.00581.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is no known strategy to differentiate which multicomponent electrograms in sinus rhythm maintain reentrant ventricular tachycardia (VT). Low entropy in the voltage breakdown of a multicomponent electrogram can localize conditions suitable for reentry but has not been validated against the classic VT activation mapping. We examined whether low entropy in a late and diversely activated ventricular scar region characterizes and differentiates the diastolic path of VT and represents protected tissue channels devoid of side branches. Intraoperative bipolar electrogram (BiEGM) activation and entropy maps were obtained during sinus rhythm in 17 patients with ischemic cardiomyopathy and compared with diastolic activation paths of VT (total of 39 VTs). Mathematical modeling of a zigzag main channel with side branches was also used to further validate structural representation of low entropy in the ventricular scar. A median of one region per patient (range: 1–2 regions) was identified in sinus rhythm, in which BiEGMwith the latest mean activation time and adjacent minimum entropy were assembled together in a high-activation dispersion region. These regions accurately recognized diastolic paths of 34 VTs, often to multiple inducible VTs within a single individual arrhythmogenic region. In mathematical modeling, side branching from the main channel had a strong influence on the BiEGMcomposition along the main channel. The BiEGMobtained from a long unbranched channel had the lowest entropy compared with those with multiple side branches. In conclusion, among a population of multicomponent sinus electrograms, those that demonstrate low entropy and are delayed colocalize to critical long-protected channels of VT. This information is pertinent for planning VT ablation in sinus rhythm.NEW & NOTEWORTHY Entropy is a measure to quantify breakdown in information. Electrograms from a protected tissue channel can only possess a few states in their voltage and thus less information. In contrast, current-load interactions from side branches in unprotected channels introduce a number of dissimilar voltage deflections and thus high information. We compare here a mapping approach based on entropy against a rigorous reference standard of activation mapping during VT and entropy was assessed in sinus rhythm.
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Affiliation(s)
- Sachin Nayyar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Eugene Downar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Mohammadali Beheshti
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Timothy Liang
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Karl Magtibay
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Abhishek Bhaskaran
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
| | - Yawer Saeed
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada
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194
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Jansen HJ, Mackasey M, Moghtadaei M, Liu Y, Kaur J, Egom EE, Tuomi JM, Rafferty SA, Kirkby AW, Rose RA. NPR-C (Natriuretic Peptide Receptor-C) Modulates the Progression of Angiotensin II–Mediated Atrial Fibrillation and Atrial Remodeling in Mice. Circ Arrhythm Electrophysiol 2019; 12:e006863. [DOI: 10.1161/circep.118.006863] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Hailey J. Jansen
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
| | - Martin Mackasey
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
| | - Motahareh Moghtadaei
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia (M. Moghtadaei, E.E.E., S.A.R.)
| | - Yingjie Liu
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
| | - Jaspreet Kaur
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
| | - Emmanuel E. Egom
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia (M. Moghtadaei, E.E.E., S.A.R.)
| | - Jari M. Tuomi
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada (J.M.T.)
| | - Sara A. Rafferty
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia (M. Moghtadaei, E.E.E., S.A.R.)
| | - Adam W. Kirkby
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
| | - Robert A. Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
- Department of Physiology and Pharmacology (H.J.J., M. Mackasey, Y.L., J.K., A.W.K., R.A.R.), Cumming School of Medicine, University of Calgary, Alberta
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195
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Wilders R. Cellular Mechanisms of Sinus Node Dysfunction in Carriers of the SCN5A-E161K Mutation and Role of the H558R Polymorphism. Front Physiol 2018; 9:1795. [PMID: 30618807 PMCID: PMC6305593 DOI: 10.3389/fphys.2018.01795] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/29/2018] [Indexed: 12/16/2022] Open
Abstract
Background: Carriers of the E161K mutation in the SCN5A gene, encoding the NaV1.5 pore-forming α-subunit of the ion channel carrying the fast sodium current (INa), show sinus bradycardia and occasional exit block. Voltage clamp experiments in mammalian expression systems revealed a mutation-induced 2.5- to 4-fold reduction in INa peak current density as well as a +19 mV shift and reduced steepness of the steady-state activation curve. The highly common H558R polymorphism in NaV1.5 limits this shift to +13 mV, but also introduces a -10 mV shift in steady-state inactivation. Aim: We assessed the cellular mechanism by which the E161K mutation causes sinus node dysfunction in heterozygous mutation carriers as well as the potential role of the H558R polymorphism. Methods: We incorporated the mutation-induced changes in INa into the Fabbri-Severi model of a single human sinoatrial node cell and the Maleckar et al. human atrial cell model, and carried out simulations under control conditions and over a wide range of acetylcholine levels. Results: In absence of the H558R polymorphism, the E161K mutation increased the basic cycle length of the sinoatrial node cell from 813 to 866 ms. In the simulated presence of 10 and 25 nM acetylcholine, basic cycle length increased from 1027 to 1131 and from 1448 to 1795 ms, respectively. The increase in cycle length was the result of a significant slowing of diastolic depolarization. The mutation-induced reduction in INa window current had reduced the contribution of the mutant component of INa to the net membrane current during diastolic depolarization to effectively zero. Highly similar results were obtained in presence of the H558R polymorphism. Atrial excitability was reduced, both in absence and presence of the H558R polymorphism, as reflected by an increase in threshold stimulus current and a concomitant decrease in capacitive current of the atrial cell. Conclusion: We conclude that the experimentally identified mutation-induced changes in INa can explain the clinically observed sinus bradycardia and potentially the occasional exit block. Furthermore, we conclude that the common H558R polymorphism does not significantly alter the effects of the E161K mutation and can thus not explain the reduced penetrance of the E161K mutation.
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Affiliation(s)
- Ronald Wilders
- Department of Medical Biology, Amsterdam University Medical Centers, Amsterdam, Netherlands
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196
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Connolly A, Kelly A, Campos FO, Myles R, Smith G, Bishop MJ. Ventricular Endocardial Tissue Geometry Affects Stimulus Threshold and Effective Refractory Period. Biophys J 2018; 115:2486-2498. [PMID: 30503533 PMCID: PMC6301915 DOI: 10.1016/j.bpj.2018.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 10/15/2018] [Accepted: 11/05/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Understanding the biophysical processes by which electrical stimuli applied to cardiac tissue may result in local activation is important in both the experimental and clinical electrophysiology laboratory environments, as well as for gaining a more in-depth knowledge of the mechanisms of focal-trigger-induced arrhythmias. Previous computational models have predicted that local myocardial tissue architecture alone may significantly modulate tissue excitability, affecting both the local stimulus current required to excite the tissue and the local effective refractory period (ERP). In this work, we present experimental validation of this structural modulation of local tissue excitability on the endocardial tissue surface, use computational models to provide mechanistic understanding of this phenomena in relation to localized changes in electrotonic loading, and demonstrate its implications for the capture of afterdepolarizations. METHODS AND RESULTS Experiments on rabbit ventricular wedge preparations showed that endocardial ridges (surfaces of negative mean curvature) had a stimulus capture threshold that was 0.21 ± 0.03 V less than endocardial grooves (surfaces of positive mean curvature) for pairwise comparison (24% reduction, corresponding to 56.2 ± 6.4% of the energy). When stimulated at the minimal stimulus strength for capture, ridge locations showed a shorter ERP than grooves (n = 6, mean pairwise difference 7.4 ± 4.2 ms). When each site was stimulated with identical-strength stimuli, the difference in ERP was further increased (mean pairwise difference 15.8 ± 5.3 ms). Computational bidomain models of highly idealized cylindrical endocardial structures qualitatively agreed with these findings, showing that such changes in excitability are driven by structural modulation in electrotonic loading, quantifying this relationship as a function of surface curvature. Simulations further showed that capture of delayed afterdepolarizations was more likely in trabecular ridges than grooves, driven by this difference in loading. CONCLUSIONS We have demonstrated experimentally and explained mechanistically in computer simulations that the ability to capture tissue on the endocardial surface depends upon the local tissue architecture. These findings have important implications for deepening our understanding of excitability differences related to anatomical structure during stimulus application that may have important applications in the translation of novel experimental optogenetics pacing strategies. The uncovered preferential vulnerability to capture of afterdepolarizations of endocardial ridges, compared to grooves, provides important insight for understanding the mechanisms of focal-trigger-induced arrhythmias.
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Affiliation(s)
- Adam Connolly
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Allen Kelly
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Fernando O Campos
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Rachel Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Godfrey Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Martin J Bishop
- Department of Bioengineering, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
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197
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Nayyar S, Kuklik P, Tomlinson G, Suszko A, Chauhan VS. Differential pacing from two sites to diagnose risk of ventricular arrhythmia and death. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2018; 42:189-200. [PMID: 30515873 DOI: 10.1111/pace.13566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 11/25/2018] [Indexed: 12/01/2022]
Abstract
BACKGROUND QRS abnormalities may not be apparent in sinus rhythm in electrically stable cardiomyopathy patients who can have quiescent but highly arrhythmogenic substrate. Here, we test the hypothesis that differential changes in QRS construction during right-ventricular apex pacing (RVP) as opposed to atrial pacing (AP) will identify latent substrate for ventricular arrhythmias (VA) and death. METHODS Forty patients with cardiomyopathy free of VA underwent baseline 114-electrode body-surface electrocardiogram during AP (100 beats per minute [bpm]) and RVP (100 and 120 bpm). The filtered-averaged QRS at each electrode was deconstructed into individual intra-QRS and post-QRS ventricular myopotentials (VMP ). The primary outcome was VA or death. Prognostic accuracy of VMP was validated using V1 to V6 leads in another prospective cohort of 44-cardiomyopathy patients. RESULTS Twenty-six patients were eligible for initial analysis. After 5 ± 2 years of follow-up, eight (31%) patients had VA (VAPos ) while rest were uneventful (VANeg ). During AP100 , VAPos patients expressed more VMP than VANeg patients (16 ± 1 vs 12 ± 1, P = 0.02). RVP100 and RVP120 in VAPos patients introduced an additional 5.5 ± 0.5 and 6.0 ± 0.5 VMP (P < 0.0001 vs AP100 ). The relative change with RVP120 versus AP100 in VANeg patients exceeded VAPos patients by 1.2 ± 0.5 VMP (P = 0.03). Increment in VMP count of <8 in lead-V5 with RVP120 compared to AP100 best predicted VA (area under curve 0.81, P = 0.01). In the validation cohort, primary outcome occurred in 13 (33%) patients. Native QRS features and AP100 alone failed to predict primary outcome. Patients with increment in VMP count of <8 in lead-V5 with RVP120 versus AP100 had 7.9-fold increased risk of primary outcome (95% confidence interval 1.01, 61.61; P = 0.049). CONCLUSION Cardiomyopathy patients at risk of VA or death perturb the QRS less than low-risk patients with differential pacing. This functional response may be useful to identify arrhythmogenic substrate.
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Affiliation(s)
- Sachin Nayyar
- Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
| | - Pawel Kuklik
- Department of Cardiology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - George Tomlinson
- Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
| | - Adrian Suszko
- Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
| | - Vijay S Chauhan
- Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
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198
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MacQueen LA, Sheehy SP, Chantre CO, Zimmerman JF, Pasqualini FS, Liu X, Goss JA, Campbell PH, Gonzalez GM, Park SJ, Capulli AK, Ferrier JP, Kosar TF, Mahadevan L, Pu WT, Parker KK. A tissue-engineered scale model of the heart ventricle. Nat Biomed Eng 2018; 2:930-941. [PMID: 31015723 PMCID: PMC6774355 DOI: 10.1038/s41551-018-0271-5] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 06/20/2018] [Indexed: 02/08/2023]
Abstract
Laboratory studies of the heart use cell and tissue cultures to dissect heart function yet rely on animal models to measure pressure and volume dynamics. Here, we report tissue-engineered scale models of the human left ventricle, made of nanofibrous scaffolds that promote native-like anisotropic myocardial tissue genesis and chamber-level contractile function. Incorporating neonatal rat ventricular myocytes or cardiomyocytes derived from human induced pluripotent stem cells, the tissue-engineered ventricles have a diastolic chamber volume of ~500 µl (comparable to that of the native rat ventricle and approximately 1/250 the size of the human ventricle), and ejection fractions and contractile work 50-250 times smaller and 104-108 times smaller than the corresponding values for rodent and human ventricles, respectively. We also measured tissue coverage and alignment, calcium-transient propagation and pressure-volume loops in the presence or absence of test compounds. Moreover, we describe an instrumented bioreactor with ventricular-assist capabilities, and provide a proof-of-concept disease model of structural arrhythmia. The model ventricles can be evaluated with the same assays used in animal models and in clinical settings.
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Affiliation(s)
- Luke A MacQueen
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Sean P Sheehy
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Christophe O Chantre
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - John F Zimmerman
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Francesco S Pasqualini
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Xujie Liu
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
| | - Josue A Goss
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Patrick H Campbell
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Grant M Gonzalez
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Sung-Jin Park
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Andrew K Capulli
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - John P Ferrier
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - T Fettah Kosar
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - L Mahadevan
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, MA, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - William T Pu
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Kevin Kit Parker
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
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199
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Rossi S, Gaeta S, Griffith BE, Henriquez CS. Muscle Thickness and Curvature Influence Atrial Conduction Velocities. Front Physiol 2018; 9:1344. [PMID: 30420809 PMCID: PMC6215968 DOI: 10.3389/fphys.2018.01344] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/06/2018] [Indexed: 12/04/2022] Open
Abstract
Electroanatomical mapping is currently used to provide clinicians with information about the electrophysiological state of the heart and to guide interventions like ablation. These maps can be used to identify ectopic triggers of an arrhythmia such as atrial fibrillation (AF) or changes in the conduction velocity (CV) that have been associated with poor cell to cell coupling or fibrosis. Unfortunately, many factors are known to affect CV, including membrane excitability, pacing rate, wavefront curvature, and bath loading, making interpretation challenging. In this work, we show how endocardial conduction velocities are also affected by the geometrical factors of muscle thickness and wall curvature. Using an idealized three-dimensional strand, we show that transverse conductivities and boundary conditions can slow down or speed up signal propagation, depending on the curvature of the muscle tissue. In fact, a planar wavefront that is parallel to a straight line normal to the mid-surface does not remain normal to the mid-surface in a curved domain. We further demonstrate that the conclusions drawn from the idealized test case can be used to explain spatial changes in conduction velocities in a patient-specific reconstruction of the left atrial posterior wall. The simulations suggest that the widespread assumption of treating atrial muscle as a two-dimensional manifold for electrophysiological simulations will not accurately represent the endocardial conduction velocities in regions of the heart thicker than 0.5 mm with significant wall curvature.
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Affiliation(s)
- Simone Rossi
- Cardiovascular Modeling and Simulation Laboratory, Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina, Chapel Hill, NC, United States
| | - Stephen Gaeta
- Clinical Cardiac Electrophysiology/Cardiology Division, Duke University Medical Center, Durham, NC, United States
| | - Boyce E. Griffith
- Cardiovascular Modeling and Simulation Laboratory, Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina, Chapel Hill, NC, United States
- Departments of Mathematics, Applied Physical Sciences, and Biomedical Engineering, University of North Carolina, Chapel Hill, NC, United States
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, United States
| | - Craig S. Henriquez
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
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200
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Abstract
BACKGROUND Among his major cardiac electrophysiological contributions, Miles Vaughan Williams (1918-2016) provided a classification of antiarrhythmic drugs that remains central to their clinical use. METHODS We survey implications of subsequent discoveries concerning sarcolemmal, sarcoplasmic reticular, and cytosolic biomolecules, developing an expanded but pragmatic classification that encompasses approved and potential antiarrhythmic drugs on this centenary of his birth. RESULTS We first consider the range of pharmacological targets, tracking these through to cellular electrophysiological effects. We retain the original Vaughan Williams Classes I through IV but subcategorize these divisions in light of more recent developments, including the existence of Na+ current components (for Class I), advances in autonomic (often G protein-mediated) signaling (for Class II), K+ channel subspecies (for Class III), and novel molecular targets related to Ca2+ homeostasis (for Class IV). We introduce new classes based on additional targets, including channels involved in automaticity, mechanically sensitive ion channels, connexins controlling electrotonic cell coupling, and molecules underlying longer-term signaling processes affecting structural remodeling. Inclusion of this widened range of targets and their physiological sequelae provides a framework for a modernized classification of established antiarrhythmic drugs based on their pharmacological targets. The revised classification allows for the existence of multiple drug targets/actions and for adverse, sometimes actually proarrhythmic, effects. The new scheme also aids classification of novel drugs under investigation. CONCLUSIONS We emerge with a modernized classification preserving the simplicity of the original Vaughan Williams framework while aiding our understanding and clinical management of cardiac arrhythmic events and facilitating future developments in this area.
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Affiliation(s)
- Ming Lei
- Department of Pharmacology, University of Oxford, United Kingdom (M.L., D.A.T.)
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (M.L., L.W.)
| | - Lin Wu
- Department of Cardiology, Peking University First Hospital, Beijing, China (L.W.)
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (M.L., L.W.)
| | - Derek A Terrar
- Department of Pharmacology, University of Oxford, United Kingdom (M.L., D.A.T.)
| | - Christopher L-H Huang
- Physiological Laboratory (C.L.-H.H.), University of Cambridge, United Kingdom
- Department of Biochemistry (C.L.-H.H.). University of Cambridge, United Kingdom
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