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Yamamoto C, Trayanova NA. Atrial fibrillation: Insights from animal models, computational modeling, and clinical studies. EBioMedicine 2022; 85:104310. [PMID: 36309006 PMCID: PMC9619190 DOI: 10.1016/j.ebiom.2022.104310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/25/2022] [Accepted: 10/04/2022] [Indexed: 11/11/2022] Open
Abstract
Atrial fibrillation (AF) is the most common human arrhythmia, affecting millions of patients worldwide. A combination of risk factors and comorbidities results in complex atrial remodeling, which increases AF vulnerability and persistence. Insights from animal models, clinical studies, and computational modeling have advanced the understanding of the mechanisms and pathophysiology of AF. Areas of heterogeneous pathological remodeling, as well as altered electrophysiological properties, serve as a substrate for AF drivers and spontaneous activations. The complex and individualized presentation of this arrhythmia suggests that mechanisms-based personalized approaches will likely be needed to overcome current challenges in AF management. In this paper, we review the insights on the mechanisms of AF obtained from animal models and clinical studies and how computational models integrate this knowledge to advance AF clinical management. We also assess the challenges that need to be overcome to implement these mechanistic models in clinical practice.
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Affiliation(s)
- Carolyna Yamamoto
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Natalia A. Trayanova
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA,Alliance for Cardiovascular Diagnostic and Treatment Innovation (ADVANCE), Johns Hopkins University, Baltimore, MD, USA,Corresponding author. Johns Hopkins, Johns Hopkins University, United States.
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2
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Picchio V, Floris E, Derevyanchuk Y, Cozzolino C, Messina E, Pagano F, Chimenti I, Gaetani R. Multicellular 3D Models for the Study of Cardiac Fibrosis. Int J Mol Sci 2022; 23:ijms231911642. [PMID: 36232943 PMCID: PMC9569892 DOI: 10.3390/ijms231911642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/19/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022] Open
Abstract
Ex vivo modelling systems for cardiovascular research are becoming increasingly important in reducing lab animal use and boosting personalized medicine approaches. Integrating multiple cell types in complex setups adds a higher level of significance to the models, simulating the intricate intercellular communication of the microenvironment in vivo. Cardiac fibrosis represents a key pathogenetic step in multiple cardiovascular diseases, such as ischemic and diabetic cardiomyopathies. Indeed, allowing inter-cellular interactions between cardiac stromal cells, endothelial cells, cardiomyocytes, and/or immune cells in dedicated systems could make ex vivo models of cardiac fibrosis even more relevant. Moreover, culture systems with 3D architectures further enrich the physiological significance of such in vitro models. In this review, we provide a summary of the multicellular 3D models for the study of cardiac fibrosis described in the literature, such as spontaneous microtissues, bioprinted constructs, engineered tissues, and organs-on-chip, discussing their advantages and limitations. Important discoveries on the physiopathology of cardiac fibrosis, as well as the screening of novel potential therapeutic molecules, have been reported thanks to these systems. Future developments will certainly increase their translational impact for understanding and modulating mechanisms of cardiac fibrosis even further.
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Affiliation(s)
- Vittorio Picchio
- Department of Medical Surgical Sciences and Biotechnologies, Sapienza University, 04100 Latina, Italy
| | - Erica Floris
- Department of Medical Surgical Sciences and Biotechnologies, Sapienza University, 04100 Latina, Italy
| | - Yuriy Derevyanchuk
- Department of Molecular Medicine, Sapienza University, 00161 Rome, Italy
| | - Claudia Cozzolino
- Department of Medical Surgical Sciences and Biotechnologies, Sapienza University, 04100 Latina, Italy
| | - Elisa Messina
- Department of Molecular Medicine, Sapienza University, 00161 Rome, Italy
| | - Francesca Pagano
- Institute of Biochemistry and Cell Biology, National Council of Research (IBBC-CNR), 00015 Monterotondo, Italy
| | - Isotta Chimenti
- Department of Medical Surgical Sciences and Biotechnologies, Sapienza University, 04100 Latina, Italy
- Mediterranea Cardiocentro, 80122 Napoli, Italy
- Correspondence: ; Tel.: +39-077-3175-7234
| | - Roberto Gaetani
- Department of Molecular Medicine, Sapienza University, 00161 Rome, Italy
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3
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Khwaounjoo P, Sands GB, LeGrice IJ, Ramulgun G, Ashton JL, Montgomery JM, Gillis AM, Smaill BH, Trew ML. Multimodal imaging shows fibrosis architecture and action potential dispersion are predictors of arrhythmic risk in spontaneous hypertensive rats. J Physiol 2022; 600:4119-4135. [PMID: 35984854 PMCID: PMC9544618 DOI: 10.1113/jp282526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 08/08/2022] [Indexed: 11/08/2022] Open
Abstract
Hypertensive heart disease (HHD) increases risk of ventricular tachycardia (VT) and ventricular fibrillation (VF). The roles of structural vs. electrophysiological remodelling and age vs. disease progression are not fully understood. This cross-sectional study of cardiac alterations through HHD investigates mechanistic contributions to VT/VF risk. Risk was electrically assessed in Langendorff-perfused, spontaneously hypertensive rat hearts at 6, 12 and 18 months, and paced optical membrane voltage maps were acquired from the left ventricular (LV) free wall epicardium. Distributions of LV patchy fibrosis and 3D cellular architecture in representative anterior LV mid-wall regions were quantified from macroscopic and microscopic fluorescence images of optically cleared tissue. Imaging showed increased fibrosis from 6 months, particularly in the inner LV free wall. Myocyte cross-section increased at 12 months, while inter-myocyte connections reduced markedly with fibrosis. Conduction velocity decreased from 12 months, especially transverse to the myofibre direction, with rate-dependent anisotropy at 12 and 18 months, but not earlier. Action potential duration (APD) increased when clustered by age, as did APD dispersion at 12 and 18 months. Among 10 structural, functional and age variables, the most reliably linked were VT/VF risk, general LV fibrosis, a measure quantifying patchy fibrosis, and non-age clustered APD dispersion. VT/VF risk related to a quantified measure of patchy fibrosis, but age did not factor strongly. The findings are consistent with the notion that VT/VF risk is associated with rate-dependent repolarization heterogeneity caused by structural remodelling and reduced lateral electrical coupling between LV myocytes, providing a substrate for heterogeneous intramural activation as HHD progresses. KEY POINTS: There is heightened arrhythmic risk with progression of hypertensive heart disease. Risk is related to increasing left ventricular fibrosis, but the nature of this relationship has not been quantified. This study is a novel systematic characterization of changes in active electrical properties and fibrotic remodelling during progression of hypertensive heart disease in a well-established animal disease model. Arrhythmic risk is predicted by several left ventricular measures, in particular fibrosis quantity and structure, and epicardial action potential duration dispersion. Age alone is not a good predictor of risk. An improved understanding of links between arrhythmic risk and fibrotic architectures in progressive hypertensive heart disease aids better interpretation of late gadolinium-enhanced cardiac magnetic resonance imaging and electrical mapping signals.
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Affiliation(s)
| | - Gregory B. Sands
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
| | - Ian J. LeGrice
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of PhysiologyUniversity of AucklandAucklandNew Zealand
| | - Girish Ramulgun
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,IHU‐LirycUniversity of BordeauxBordeauxFrance
| | - Jesse L. Ashton
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of PhysiologyUniversity of AucklandAucklandNew Zealand
| | | | - Anne M. Gillis
- Libin Cardiovascular Institute of AlbertaUniversity of CalgaryCalgaryAlbertaCanada
| | - Bruce H. Smaill
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
| | - Mark L. Trew
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
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Teer E, Dominick L, Mukonowenzou NC, Essop MF. HIV-Related Myocardial Fibrosis: Inflammatory Hypothesis and Crucial Role of Immune Cells Dysregulation. Cells 2022; 11:cells11182825. [PMID: 36139400 PMCID: PMC9496784 DOI: 10.3390/cells11182825] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Although the underlying mechanisms driving human immunodeficiency virus (HIV)-mediated cardiovascular diseases (CVD) onset and progression remain unclear, the role of chronic immune activation as a significant mediator is increasingly being highlighted. Chronic inflammation is a characteristic feature of CVD and considered a contributor to diastolic dysfunction, heart failure, and sudden cardiac death. This can trigger downstream effects that result in the increased release of pro-coagulant, pro-fibrotic, and pro-inflammatory cytokines. Subsequently, this can lead to an enhanced thrombotic state (by platelet activation), endothelial dysfunction, and myocardial fibrosis. Of note, recent studies have revealed that myocardial fibrosis is emerging as a mediator of HIV-related CVD. Together, such factors can eventually result in systolic and diastolic dysfunction, and an increased risk for CVD. In light of this, the current review article will focus on (a) the contributions of a chronic inflammatory state and persistent immune activation, and (b) the role of immune cells (mainly platelets) and cardiac fibrosis in terms of HIV-related CVD onset/progression. It is our opinion that such a focus may lead to the development of promising therapeutic targets for the treatment and management of CVD in HIV-positive patients.
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Affiliation(s)
- Eman Teer
- Centre for Cardio-Metabolic Research in Africa, Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Leanne Dominick
- Centre for Cardio-Metabolic Research in Africa, Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Nyasha C. Mukonowenzou
- Centre for Cardio-Metabolic Research in Africa, Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
| | - M. Faadiel Essop
- Centre for Cardio-Metabolic Research in Africa, Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa
- Correspondence: ; Tel.: +27-21-938-9388
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Premont A, Balthes S, Marr CM, Jeevaratnam K. Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation. Equine Vet J 2021; 54:262-282. [PMID: 34564902 DOI: 10.1111/evj.13518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/26/2022]
Abstract
Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.
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Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Samantha Balthes
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Celia M Marr
- Rossdales Equine Hospital and Diagnostic Centre, Newmarket, UK
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Celotto C, Sánchez C, Mountris KA, Laguna P, Pueyo E. Location of Parasympathetic Innervation Regions From Electrograms to Guide Atrial Fibrillation Ablation Therapy: An in silico Modeling Study. Front Physiol 2021; 12:674197. [PMID: 34456743 PMCID: PMC8385640 DOI: 10.3389/fphys.2021.674197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/11/2021] [Indexed: 01/18/2023] Open
Abstract
The autonomic nervous system (ANS) plays an essential role in the generation and maintenance of cardiac arrhythmias. The cardiac ANS can be divided into its extrinsic and intrinsic components, with the latter being organized in an epicardial neural network of interconnecting axons and clusters of autonomic ganglia called ganglionated plexi (GPs). GP ablation has been associated with a decreased risk of atrial fibrillation (AF) recurrence, but the accurate location of GPs is required for ablation to be effective. Although GP stimulation triggers both sympathetic and parasympathetic ANS branches, a predominance of parasympathetic activity has been shown. This study aims was to develop a method to locate atrial parasympathetic innervation sites based on measurements from a grid of electrograms (EGMs). Electrophysiological models representative of non-AF, paroxysmal AF (PxAF), and persistent AF (PsAF) tissues were developed. Parasympathetic effects were modeled by increasing the concentration of the neurotransmitter acetylcholine (ACh) in randomly distributed circles across the tissue. Different circle sizes of ACh and fibrosis geometries were considered, accounting for both uniform diffuse and non-uniform diffuse fibrosis. Computational simulations were performed, from which unipolar EGMs were computed in a 16 × 1 6 electrode mesh. Different distances of the electrodes to the tissue (0.5, 1, and 2 mm) and noise levels with signal-to-noise ratio (SNR) values of 0, 5, 10, 15, and 20 dB were tested. The amplitude of the atrial EGM repolarization wave was found to be representative of the presence or absence of ACh release sites, with larger positive amplitudes indicating that the electrode was placed over an ACh region. Statistical analysis was performed to identify the optimal thresholds for the identification of ACh sites. In all non-AF, PxAF, and PsAF tissues, the repolarization amplitude rendered successful identification. The algorithm performed better in the absence of fibrosis or when fibrosis was uniformly diffuse, with a mean accuracy of 0.94 in contrast with a mean accuracy of 0.89 for non-uniform diffuse fibrotic cases. The algorithm was robust against noise and worked for the tested ranges of electrode-to-tissue distance. In conclusion, the results from this study support the feasibility to locate atrial parasympathetic innervation sites from the amplitude of repolarization wave.
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Affiliation(s)
- Chiara Celotto
- Aragon Institute of Engineering Research-I3A-, University of Zaragoza, IIS Aragón, Zaragoza, Spain
- CIBER in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
| | - Carlos Sánchez
- Aragon Institute of Engineering Research-I3A-, University of Zaragoza, IIS Aragón, Zaragoza, Spain
- CIBER in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
| | - Konstantinos A. Mountris
- Aragon Institute of Engineering Research-I3A-, University of Zaragoza, IIS Aragón, Zaragoza, Spain
- CIBER in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
| | - Pablo Laguna
- Aragon Institute of Engineering Research-I3A-, University of Zaragoza, IIS Aragón, Zaragoza, Spain
- CIBER in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
| | - Esther Pueyo
- Aragon Institute of Engineering Research-I3A-, University of Zaragoza, IIS Aragón, Zaragoza, Spain
- CIBER in Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain
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Varma N. Perimitral ventricular tachycardia associated with remote inferior myocardial infarction. J Cardiovasc Electrophysiol 2021; 32:2228-2237. [PMID: 34191359 DOI: 10.1111/jce.15143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 05/31/2021] [Accepted: 06/18/2021] [Indexed: 12/01/2022]
Abstract
INTRODUCTION Circuits underlying ventricular tachycardias (VTs) accompanying remote inferior myocardial infarction (IMI) are regarded to be located in the scar. Rotation around the mitral annulus (MA) had also been postulated. We tested whether entrainment mapping could confirm whether MA rotation in VTs post-IMI represented a "driving circuit." METHODS Three patients with IMI (male, left ventricular ejection fraction range 13%-40%) with hemodynamically tolerated VT (cycle length 365-690 ms) were studied with activation and entrainment mapping of the MA. RESULTS Patients showed QRS morphologies reported for VTs following IMI: LBBB (left bundle branch block) pattern and/or right bundle pattern. Entrainment revealed the entire MA perimeter constituted the circuit, that is, macroreentry (path length greater than 13 cm in one case). Areas showing prolonged fractionated electrograms (accounting for over 50% of tachycardia cycle length) demonstrated concealed entrainment indicative of slow conduction through (and not around) the scar. Concealed entrainment was observed along the MA, with similar stimulus-QRS intervals when pacing during normal sinus rhythm. Radiofrequency ablation of the inferior isthmus from scar to MA (epicardially in one case) abolished tachycardia. In follow-up, two patients had no VT recurrence and maintained NYHA Class 1 functional status during several years of follow-up. The other patient continued to deteriorate with rapidly progressive HF, had recurrent VT within 3 months, proceeding to transplant within 9 months. Our findings confirm a single-loop perimitral circuit, which is largely (if not exclusively) protected by anatomical barriers. This differs from the established "figure-of-8" VT model. CONCLUSION Single-loop macroreentrant mitral annular circuits may underlie some VTs following inferior wall infarcts.
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Affiliation(s)
- Niraj Varma
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, USA
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Mikhailov AV, Kalyanasundaram A, Li N, Scott SS, Artiga EJ, Subr MM, Zhao J, Hansen BJ, Hummel JD, Fedorov VV. Comprehensive evaluation of electrophysiological and 3D structural features of human atrial myocardium with insights on atrial fibrillation maintenance mechanisms. J Mol Cell Cardiol 2020; 151:56-71. [PMID: 33130148 DOI: 10.1016/j.yjmcc.2020.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 12/14/2022]
Abstract
Atrial fibrillation (AF) occurrence and maintenance is associated with progressive remodeling of electrophysiological (repolarization and conduction) and 3D structural (fibrosis, fiber orientations, and wall thickness) features of the human atria. Significant diversity in AF etiology leads to heterogeneous arrhythmogenic electrophysiological and structural substrates within the 3D structure of the human atria. Since current clinical methods have yet to fully resolve the patient-specific arrhythmogenic substrates, mechanism-based AF treatments remain underdeveloped. Here, we review current knowledge from in-vivo, ex-vivo, and in-vitro human heart studies, and discuss how these studies may provide new insights on the synergy of atrial electrophysiological and 3D structural features in AF maintenance. In-vitro studies on surgically acquired human atrial samples provide a great opportunity to study a wide spectrum of AF pathology, including functional changes in single-cell action potentials, ion channels, and gene/protein expression. However, limited size of the samples prevents evaluation of heterogeneous AF substrates and reentrant mechanisms. In contrast, coronary-perfused ex-vivo human hearts can be studied with state-of-the-art functional and structural technologies, such as high-resolution near-infrared optical mapping and contrast-enhanced MRI. These imaging modalities can resolve atrial arrhythmogenic substrates and their role in reentrant mechanisms maintaining AF and validate clinical approaches. Nonetheless, longitudinal studies are not feasible in explanted human hearts. As no approach is perfect, we suggest that combining the strengths of direct human atrial studies with high fidelity approaches available in the laboratory and in realistic patient-specific computer models would elucidate deeper knowledge of AF mechanisms. We propose that a comprehensive translational pipeline from ex-vivo human heart studies to longitudinal clinically relevant AF animal studies and finally to clinical trials is necessary to identify patient-specific arrhythmogenic substrates and develop novel AF treatments.
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Affiliation(s)
- Aleksei V Mikhailov
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Arrhythmology Research Department, Almazov National Medical Research Centre, Saint-Petersburg, Russia
| | - Anuradha Kalyanasundaram
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ning Li
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Shane S Scott
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Esthela J Artiga
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Megan M Subr
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Brian J Hansen
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - John D Hummel
- Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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Hansen BJ, Zhao J, Helfrich KM, Li N, Iancau A, Zolotarev AM, Zakharkin SO, Kalyanasundaram A, Subr M, Dastagir N, Sharma R, Artiga EJ, Salgia N, Houmsse MM, Kahaly O, Janssen PML, Mohler PJ, Mokadam NA, Whitson BA, Afzal MR, Simonetti OP, Hummel JD, Fedorov VV. Unmasking Arrhythmogenic Hubs of Reentry Driving Persistent Atrial Fibrillation for Patient-Specific Treatment. J Am Heart Assoc 2020; 9:e017789. [PMID: 33006292 PMCID: PMC7792422 DOI: 10.1161/jaha.120.017789] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background Atrial fibrillation (AF) driver mechanisms are obscured to clinical multielectrode mapping approaches that provide partial, surface‐only visualization of unstable 3‐dimensional atrial conduction. We hypothesized that transient modulation of refractoriness by pharmacologic challenge during multielectrode mapping improves visualization of hidden paths of reentrant AF drivers for targeted ablation. Methods and Results Pharmacologic challenge with adenosine was tested in ex vivo human hearts with a history of AF and cardiac diseases by multielectrode and high‐resolution subsurface near‐infrared optical mapping, integrated with 3‐dimensional structural imaging and heart‐specific computational simulations. Adenosine challenge was also studied on acutely terminated AF drivers in 10 patients with persistent AF. Ex vivo, adenosine stabilized reentrant driver paths within arrhythmogenic fibrotic hubs and improved visualization of reentrant paths, previously seen as focal or unstable breakthrough activation pattern, for targeted AF ablation. Computational simulations suggested that shortening of atrial refractoriness by adenosine may (1) improve driver stability by annihilating spatially unstable functional blocks and tightening reentrant circuits around fibrotic substrates, thus unmasking the common reentrant path; and (2) destabilize already stable reentrant drivers along fibrotic substrates by accelerating competing fibrillatory wavelets or secondary drivers. In patients with persistent AF, adenosine challenge unmasked hidden common reentry paths (9/15 AF drivers, 41±26% to 68±25% visualization), but worsened visualization of previously visible reentry paths (6/15, 74±14% to 34±12%). AF driver ablation led to acute termination of AF. Conclusions Our ex vivo to in vivo human translational study suggests that transiently altering atrial refractoriness can stabilize reentrant paths and unmask arrhythmogenic hubs to guide targeted AF driver ablation treatment.
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Affiliation(s)
- Brian J Hansen
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | | | - Katelynn M Helfrich
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Ning Li
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Alexander Iancau
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH
| | - Alexander M Zolotarev
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Skolkovo Institute of Science and Technology Moscow Russia
| | - Stanislav O Zakharkin
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH
| | - Anuradha Kalyanasundaram
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Megan Subr
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH
| | | | | | - Esthela J Artiga
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Nicholas Salgia
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH
| | - Mustafa M Houmsse
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH
| | - Omar Kahaly
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Department of Internal Medicine The Ohio State University Wexner Medical Center Columbus OH
| | - Paul M L Janssen
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Peter J Mohler
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
| | - Nahush A Mokadam
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Division of Cardiac Surgery The Ohio State University Wexner Medical Center Columbus OH
| | - Bryan A Whitson
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Division of Cardiac Surgery The Ohio State University Wexner Medical Center Columbus OH
| | - Muhammad R Afzal
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Department of Internal Medicine The Ohio State University Wexner Medical Center Columbus OH
| | - Orlando P Simonetti
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Department of Biomedical Engineering The Ohio State University Wexner Medical Center Columbus OH
| | - John D Hummel
- Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH.,Department of Internal Medicine The Ohio State University Wexner Medical Center Columbus OH
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology and Frick Center for Heart Failure and Arrhythmia The Ohio State University Wexner Medical Center Columbus OH.,Davis Heart & Lung Research InstituteThe Ohio State University Wexner Medical Center Columbus OH
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10
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Wisnoskey BJ, Varma N. Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate. Heart Rhythm O2 2020; 1:85-95. [PMID: 34113862 PMCID: PMC8183968 DOI: 10.1016/j.hroo.2020.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background Cardiac resynchronization therapy (CRT) uses left ventricular (LV) pacing to restore rapid synchronized LV activation when it is delayed in patients with myocardial disease. Objective Although intrinsic LV activation delays are understood, little is known about reactions to LV stimulation and whether they are affected by QRS duration (QRSd), morphology, LV substrate, or choice of electrode pair. The purpose of this study was to test these interactions. Methods In 120 heart failure patients with left bundle branch block (LBBB) and QRS >120 ms receiving CRT with quadripolar LV leads, device-based measurements of intrinsic activation delay (qLV) and paced inter- (and intra-) LV conduction times were evaluated at the proximal and distal LV bipoles. Results During intrinsic conduction, qLV varied little between the proximal and distal pairs in patients with LBBB (n = 120; age 68 ± 11 years; 63% male; ejection fraction 25% ± 7%; 33% ischemic cardiomyopathy; QRSd 162 ± 19 ms). A minority (30%) had conduction barriers (ie, gradients) (ΔqLV 29 ± 8 ms vs 9 ± 5 ms in patients without gradients; P <.01), which occurred equally in ischemic and nonischemic patients. A majority were functional (and not scar-mediated), as they resolved with pacing in most patients (75%). Importantly, LV-paced conduction times were unrelated to baseline QRS morphology (LBBB 166 ± 30 ms vs RBBB control 172 ± 30 ms; P = NS), longer than intrinsic conduction (166 ± 30 ms vs 129 ± 28 ms; P <.01), and varied significantly by electrode pair (ie, small distances) and etiology. Correlation between intrinsic activation delay (qLV) and LV-paced conduction time was poor (R2 = 0.278; P <.05). Conclusion LV-paced effect, which is core to CRT, is unpredictable based on conventionally used measures and should be considered during CRT optimization.
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Affiliation(s)
| | - Niraj Varma
- Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio
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11
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Trew ML, Engelman ZJ, Caldwell BJ, Lever NA, LeGrice IJ, Smaill BH. Cardiac intramural electrical mapping reveals focal delays but no conduction velocity slowing in the peri-infarct region. Am J Physiol Heart Circ Physiol 2019; 317:H743-H753. [PMID: 31419152 DOI: 10.1152/ajpheart.00154.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Altered electrical behavior alongside healed myocardial infarcts (MIs) is associated with increased risk of sudden cardiac death. However, the multidimensional mechanisms are poorly understood and described. This study characterizes, for the first time, the intramural spread of electrical activation in the peri-infarct region of chronic reperfusion MIs. Four sheep were studied 13 wk after antero-apical reperfusion infarction. Extracellular potentials (ECPs) were recorded in a ~20 × 20-mm2 region adjacent to the infarct boundary (25 plunge needles <0.5-mm diameter with 15 electrodes at 1-mm centers) during multisite stimulation. Infarct geometry and electrode locations were reconstructed from magnetic resonance images. Three-dimensional activation spread was characterized by local activation times and interpolated ECP fields (n = 191 records). Control data were acquired in 4 non-infarcted sheep (n = 96 records). Electrodes were distributed uniformly around 15 ± 5% of the intramural infarct boundary. There were marked changes in pacing success and ECP morphology across a functional border zone (BZ) ±2 mm from the boundary. Stimulation adjacent to the infarct boundary was associated with low-amplitude electrical activity within the BZ and delayed activation of surrounding myocardium. Bulk tissue depolarization occurred 3.5-14.6 mm from the pacing site for 39% of stimuli with delays of 4-37 ms, both significantly greater than control (P < 0.0001). Conduction velocity (CV) adjacent to the infarct was not reduced compared with control, consistent with structure-only computer model results. Insignificant CV slowing, irregular stimulus-site specific activation delays, and obvious indirect activation pathways strongly suggest that the substrate for conduction abnormalities in chronic MI is predominantly structural in nature.NEW & NOTEWORTHY Intramural in vivo measurements of peri-infarct electrical activity were not available before this study. We use pace-mapping in a three-dimensional electrode array to show that a subset of stimuli in the peri-infarct region initiates coordinated myocardial activation some distance from the stimulus site with substantial associated time delays. This is site dependent and heterogeneous and occurs for <50% of ectopic stimuli in the border zone. Furthermore, once coordinated activation is initiated, conduction velocity adjacent to the infarct boundary is not significantly different from control. These results give new insights to peri-infarct electrical activity and do not support the widespread view of uniform electrical remodeling in the border zone of chronic myocardial infarcts, with depressed conduction velocity throughout.
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Affiliation(s)
- Mark L Trew
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Zoar J Engelman
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Bryan J Caldwell
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Nigel A Lever
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Auckland Hospital, Auckland, New Zealand
| | - Ian J LeGrice
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Bruce H Smaill
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.,Department of Physiology, University of Auckland, Auckland, New Zealand
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12
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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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13
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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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14
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Pedrotty DM, Kuzmenko V, Karabulut E, Sugrue AM, Livia C, Vaidya VR, McLeod CJ, Asirvatham SJ, Gatenholm P, Kapa S. Three-Dimensional Printed Biopatches With Conductive Ink Facilitate Cardiac Conduction When Applied to Disrupted Myocardium. Circ Arrhythm Electrophysiol 2019; 12:e006920. [DOI: 10.1161/circep.118.006920] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Dawn M. Pedrotty
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
- Division of Cardiovascular Medicine, Department of Medicine, University of Pennsylvania, Philadelphia (D.M.P.)
| | - Volodymyr Kuzmenko
- Department of Microtechnology (V.K.), Nanoscience and Wallenberg Wood Science Center, Chalmers University, Gothenburg, Sweden
| | - Erdem Karabulut
- Department of Chemistry and Chemical Engineering (E.K., P.G.), Nanoscience and Wallenberg Wood Science Center, Chalmers University, Gothenburg, Sweden
| | - Alan M. Sugrue
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
| | - Christopher Livia
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
| | - Vaibhav R. Vaidya
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
| | - Christopher J. McLeod
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
| | - Samuel J. Asirvatham
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
| | - Paul Gatenholm
- Department of Chemistry and Chemical Engineering (E.K., P.G.), Nanoscience and Wallenberg Wood Science Center, Chalmers University, Gothenburg, Sweden
- CELLHEAL, Blacksburg, VA (P.G.)
| | - Suraj Kapa
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN (D.M.P., A.M.S., C.L., V.R.V., C.J.M., S.J.A., S.K.)
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15
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Abstract
Cardiac resynchronization therapy with left ventricular coronary sinus or epicardial pacing is an established therapy for patients with systolic heart failure and intraventricular conduction system delay, particularly left bundle branch block. Despite large-scale randomized trials demonstrating the efficacy of this therapy, clinical and echocardiographic nonresponse rates remain as high as up to 40%. His bundle pacing (HBP) has reemerged as a means to provide physiologic resynchronization in patients with bundle branch block by correcting QRS by direct capture of the His-Purkinje system. This critical appraisal reviews early clinical data, evaluates possible mechanism, and identifies areas for future investigation for HBP in resynchronization.
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Affiliation(s)
- Gaurav A Upadhyay
- The University of Chicago Medicine, Center for Arrhythmia Care, Heart and Vascular Center, 5841 South Maryland Avenue, Chicago, IL 60637, USA
| | - Roderick Tung
- The University of Chicago Medicine, Center for Arrhythmia Care, Heart and Vascular Center, 5841 South Maryland Avenue, Chicago, IL 60637, USA.
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16
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Colman MA, Perez Alday EA, Holden AV, Benson AP. Trigger vs. Substrate: Multi-Dimensional Modulation of QT-Prolongation Associated Arrhythmic Dynamics by a hERG Channel Activator. Front Physiol 2017; 8:757. [PMID: 29046643 PMCID: PMC5632683 DOI: 10.3389/fphys.2017.00757] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022] Open
Abstract
Background: Prolongation of the QT interval of the electrocardiogram (ECG), underlain by prolongation of the action potential duration (APD) at the cellular level, is linked to increased vulnerability to cardiac arrhythmia. Pharmacological management of arrhythmia associated with QT prolongation is typically achieved through attempting to restore APD to control ranges, reversing the enhanced vulnerability to Ca2+-dependent afterdepolarisations (arrhythmia triggers) and increased transmural dispersion of repolarisation (arrhythmia substrate) associated with APD prolongation. However, such pharmacological modulation has been demonstrated to have limited effectiveness. Understanding the integrative functional impact of pharmacological modulation requires simultaneous investigation of both the trigger and substrate. Methods: We implemented a multi-scale (cell and tissue) in silico approach using a model of the human ventricular action potential, integrated with a model of stochastic 3D spatiotemporal Ca2+ dynamics, and parameter modification to mimic prolonged QT conditions. We used these models to examine the efficacy of the hERG activator MC-II-157c in restoring APD to control ranges, examined its effects on arrhythmia triggers and substrates, and the interaction of these arrhythmia triggers and substrates. Results: QT prolongation conditions promoted the development of spontaneous release events underlying afterdepolarisations during rapid pacing. MC-II-157c applied to prolonged QT conditions shortened the APD, inhibited the development of afterdepolarisations and reduced the probability of afterdepolarisations manifesting as triggered activity in single cells. In tissue, QT prolongation resulted in an increased transmural dispersion of repolarisation, which manifested as an increased vulnerable window for uni-directional conduction block. In some cases, MC-II-157c further increased the vulnerable window through its effects on INa. The combination of stochastic release event modulation and transmural dispersion of repolarisation modulation by MC-II-157c resulted in an integrative behavior wherein the arrhythmia trigger is reduced but the arrhythmia substrate is increased, leading to variable and non-linear overall vulnerability to arrhythmia. Conclusion: The relative balance of reduced trigger and increased substrate underlies a multi-dimensional role of MC-II-157c in modulation of cardiac arrhythmia vulnerability associated with prolonged QT interval.
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Affiliation(s)
- Michael A Colman
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - Erick A Perez Alday
- Division of Cardiovascular Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Arun V Holden
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - Alan P Benson
- School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
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17
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Zhao J, Hansen BJ, Wang Y, Csepe TA, Sul LV, Tang A, Yuan Y, Li N, Bratasz A, Powell KA, Kilic A, Mohler PJ, Janssen PML, Weiss R, Simonetti OP, Hummel JD, Fedorov VV. Three-dimensional Integrated Functional, Structural, and Computational Mapping to Define the Structural "Fingerprints" of Heart-Specific Atrial Fibrillation Drivers in Human Heart Ex Vivo. J Am Heart Assoc 2017; 6:JAHA.117.005922. [PMID: 28862969 PMCID: PMC5586436 DOI: 10.1161/jaha.117.005922] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Structural remodeling of human atria plays a key role in sustaining atrial fibrillation (AF), but insufficient quantitative analysis of human atrial structure impedes the treatment of AF. We aimed to develop a novel 3-dimensional (3D) structural and computational simulation analysis tool that could reveal the structural contributors to human reentrant AF drivers. METHODS AND RESULTS High-resolution panoramic epicardial optical mapping of the coronary-perfused explanted intact human atria (63-year-old woman, chronic hypertension, heart weight 608 g) was conducted during sinus rhythm and sustained AF maintained by spatially stable reentrant AF drivers in the left and right atrium. The whole atria (107×61×85 mm3) were then imaged with contrast-enhancement MRI (9.4 T, 180×180×360-μm3 resolution). The entire 3D human atria were analyzed for wall thickness (0.4-11.7 mm), myofiber orientations, and transmural fibrosis (36.9% subendocardium; 14.2% midwall; 3.4% subepicardium). The 3D computational analysis revealed that a specific combination of wall thickness and fibrosis ranges were primarily present in the optically defined AF driver regions versus nondriver tissue. Finally, a 3D human heart-specific atrial computer model was developed by integrating 3D structural and functional mapping data to test AF induction, maintenance, and ablation strategies. This 3D model reproduced the optically defined reentrant AF drivers, which were uninducible when fibrosis and myofiber anisotropy were removed from the model. CONCLUSIONS Our novel 3D computational high-resolution framework may be used to quantitatively analyze structural substrates, such as wall thickness, myofiber orientation, and fibrosis, underlying localized AF drivers, and aid the development of new patient-specific treatments.
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Affiliation(s)
- Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Brian J Hansen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Yufeng Wang
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Thomas A Csepe
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Lidiya V Sul
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Alan Tang
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Yiming Yuan
- Auckland Bioengineering Institute, The University of Auckland, New Zealand
| | - Ning Li
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Anna Bratasz
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Kimerly A Powell
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Ahmet Kilic
- Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Peter J Mohler
- Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Paul M L Janssen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Raul Weiss
- Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Orlando P Simonetti
- Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - John D Hummel
- Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH .,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH
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18
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Fibrosis and Atrial Fibrillation: Computerized and Optical Mapping; A View into the Human Atria at Submillimeter Resolution. JACC Clin Electrophysiol 2017; 3:531-546. [PMID: 29159313 DOI: 10.1016/j.jacep.2017.05.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent studies strongly suggest that the majority of atrial fibrillation (AF) patients with diagnosed or subclinical cardiac diseases have established or even pre-existing fibrotic structural remodeling, which may lead to conduction abnormalities and reentrant activity that sustain AF. As conventional treatments fail to treat AF in far too many cases, an urgent need exists to identify specific structural arrhythmogenic fibrosis patterns, which may maintain AF, in order to identify effective ablation targets for AF treatment. However, the existing challenge is to define what exact structural remodeling within the complex 3D human atrial wall is arrhythmogenic, as well as linking arrhythmogenic fibrosis to an underlying mechanism of AF maintenance in the clinical setting. This review is focused on the role of 3D fibrosis architecture in the mechanisms of AF maintenance revealed by submillimeter, high-resolution ex-vivo imaging modalities directly of human atria, as well as from in-silico 3D computational techniques that can be able to overcome in-vivo clinical limitations. The systematic integration of functional and structural imaging ex-vivo may inform the necessary integration of electrode and structural mapping in-vivo. A holistic view of AF driver mechanisms may begin to identify the defining characteristics or "fingerprints" of reentrant AF drivers, such as 3D fibrotic architecture, in order to design optimal patient-specific ablation strategies.
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19
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Ajijola OA, Lux RL, Khahera A, Kwon O, Aliotta E, Ennis DB, Fishbein MC, Ardell JL, Shivkumar K. Sympathetic modulation of electrical activation in normal and infarcted myocardium: implications for arrhythmogenesis. Am J Physiol Heart Circ Physiol 2017; 312:H608-H621. [PMID: 28087519 DOI: 10.1152/ajpheart.00575.2016] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 11/22/2022]
Abstract
The influence of cardiac sympathetic innervation on electrical activation in normal and chronically infarcted ventricular myocardium is not understood. Yorkshire pigs with normal hearts (NL, n = 12) or anterior myocardial infarction (MI, n = 9) underwent high-resolution mapping of the anteroapical left ventricle at baseline and during left and right stellate ganglion stimulation (LSGS and RSGS, respectively). Conduction velocity (CV), activation times (ATs), and directionality of propagation were measured. Myocardial fiber orientation was determined using diffusion tensor imaging and histology. Longitudinal CV (CVL) was increased by RSGS (0.98 ± 0.11 vs. 1.2 ± 0.14m/s, P < 0.001) but not transverse CV (CVT). This increase was abrogated by β-adrenergic receptor and gap junction (GJ) blockade. Neither CVL nor CVT was increased by LSGS. In the peri-infarct region, both RSGS and LSGS shortened ARIs in sinus rhythm (423 ± 37 vs. 322 ± 30 ms, P < 0.001, and 423 ± 36 vs. 398 ± 36 ms, P = 0.035, respectively) and altered activation patterns in all animals. CV, as estimated by mean ATs, increased in a directionally dependent manner by RSGS (14.6 ± 1.2 vs. 17.3 ± 1.6 ms, P = 0.015), associated with GJ lateralization. RSGS and LSGS inhomogeneously modulated AT and induced relative or absolute functional activation delay in parts of the mapped regions in 75 and 67%, respectively, in MI animals, and in 0 and 15%, respectively, in control animals (P < 0.001 for both). In conclusion, sympathoexcitation increases CV in normal myocardium and modulates activation propagation in peri-infarcted ventricular myocardium. These data demonstrate functional control of arrhythmogenic peri-infarct substrates by sympathetic nerves and in part explain the temporal nature of arrhythmogenesis.NEW & NOTEWORTHY This study demonstrates regional control of conduction velocity in normal hearts by sympathetic nerves. In infarcted hearts, however, not only is modulation of propagation heterogeneous, some regions showed paradoxical conduction slowing. Sympathoexcitation altered propagation in all infarcted hearts studied, and we describe the temporal arrhythmogenic potential of these findings.Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/sympathetic-nerves-and-cardiac-propagation/.
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Affiliation(s)
- Olujimi A Ajijola
- Cardiac Arrhythmia Center, University of California, Los Angeles, California; .,Neurocardiology Research Center of Excellence, University of California, Los Angeles, California
| | - Robert L Lux
- Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Anadjeet Khahera
- Cardiac Arrhythmia Center, University of California, Los Angeles, California
| | - OhJin Kwon
- Cardiac Arrhythmia Center, University of California, Los Angeles, California
| | - Eric Aliotta
- Department of Radiology, University of California, Los Angeles, California
| | - Daniel B Ennis
- Department of Radiology, University of California, Los Angeles, California
| | - Michael C Fishbein
- Department of Pathology, University of California, Los Angeles, California; and
| | - Jeffrey L Ardell
- Cardiac Arrhythmia Center, University of California, Los Angeles, California.,Neurocardiology Research Center of Excellence, University of California, Los Angeles, California
| | - Kalyanam Shivkumar
- Cardiac Arrhythmia Center, University of California, Los Angeles, California.,Neurocardiology Research Center of Excellence, University of California, Los Angeles, California
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20
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Reentry and Ectopic Pacemakers Emerge in a Three-Dimensional Model for a Slab of Cardiac Tissue with Diffuse Microfibrosis near the Percolation Threshold. PLoS One 2016; 11:e0166972. [PMID: 27875591 PMCID: PMC5119821 DOI: 10.1371/journal.pone.0166972] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 11/07/2016] [Indexed: 02/07/2023] Open
Abstract
Arrhythmias in cardiac tissue are generally associated with irregular electrical wave propagation in the heart. Cardiac tissue is formed by a discrete cell network, which is often heterogeneous. Recently, it was shown in simulations of two-dimensional (2D) discrete models of cardiac tissue that a wave crossing a fibrotic, heterogeneous region may produce reentry and transient or persistent ectopic activity provided the fraction of conducting connections is just above the percolation threshold. Here, we investigate the occurrence of these phenomena in three-dimensions by simulations of a discrete model representing a thin slab of cardiac tissue. This is motivated (i) by the necessity to study the relevance and properties of the percolation-related mechanism for the emergence of microreentries in three dimensions and (ii) by the fact that atrial tissue is quite thin in comparison with ventricular tissue. Here, we simplify the model by neglecting details of tissue anatomy, e. g. geometries of atria or ventricles and the anisotropy in the conductivity. Hence, our modeling study is confined to the investigation of the effect of the tissue thickness as well as to the comparison of the dynamics of electrical excitation in a 2D layer with the one in a 3D slab. Our results indicate a strong and non-trivial effect of the thickness even for thin tissue slabs on the probability of microreentries and ectopic beat generation. The strong correlation of the occurrence of microreentry with the percolation threshold reported earlier in 2D layers persists in 3D slabs. Finally, a qualitative agreement of 3D simulated electrograms in the fibrotic region with the experimentally observed complex fractional atrial electrograms (CFAE) as well as strong difference between simulated electrograms in 2D and 3D were found for the cases where reentry and ectopic activity were triggered by the micro-fibrotic region.
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21
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Spencer TM, Blumenstein RF, Pryse KM, Lee SL, Glaubke DA, Carlson BE, Elson EL, Genin GM. Fibroblasts Slow Conduction Velocity in a Reconstituted Tissue Model of Fibrotic Cardiomyopathy. ACS Biomater Sci Eng 2016; 3:3022-3028. [PMID: 31119190 DOI: 10.1021/acsbiomaterials.6b00576] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Myocardial function deteriorates over the course of fibrotic cardiomyopathy, due to electrophysiological and mechanical effects of myofibroblasts that are not completely understood. Although a range of experimental model systems and associated theoretical treatments exist at the levels of isolated cardiomyocytes and planar co-cultures of myofibroblasts and cardiomyocytes, interactions between these cell types at the tissue level are less clear. We studied these interactions through an engineered heart tissue (EHT) model of fibrotic myocardium and a mathematical model of the effects of cellular composition on EHT impulse conduction velocity. The EHT model allowed for modulation of cardiomyocyte and myofibroblast volume fractions, and observation of cell behavior in a three-dimensional environment that is more similar to native heart tissue than is planar cell culture. The cardiomyocyte and myofibroblast volume fractions determined the retardation of impulse conduction (spread of the action potential) in EHTs as measured by changes of the fluorescence of the Ca2+ probe, Fluo-2. Interpretation through our model showed retardation far in excess of predictions by homogenization theory, with conduction ceasing far below the fibroblast volume fraction associated with steric percolation. Results point to an important multiscale structural role of myofibroblasts in attenuating impulse conduction in fibrotic cardiomyopathy.
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Affiliation(s)
- Teresa M Spencer
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Ryan F Blumenstein
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Kenneth M Pryse
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,Department of Biochemistry and Molecular Biophysics, 660 S. Euclid Drive, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sheng-Lin Lee
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - David A Glaubke
- Department of Biomedical Engineering, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Brian E Carlson
- Department of Molecular and Integrative Physiology, NCRC B10 A126, 2800 Plymouth Rd., University of Michigan School of Medicine, Ann Arbor, MI 48105, USA
| | - Elliot L Elson
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,Department of Biochemistry and Molecular Biophysics, 660 S. Euclid Drive, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Biomedical Engineering, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Guy M Genin
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,NSF Center for Engineering MechanoBiology, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
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22
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Alonso S, Bär M, Echebarria B. Nonlinear physics of electrical wave propagation in the heart: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096601. [PMID: 27517161 DOI: 10.1088/0034-4885/79/9/096601] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The beating of the heart is a synchronized contraction of muscle cells (myocytes) that is triggered by a periodic sequence of electrical waves (action potentials) originating in the sino-atrial node and propagating over the atria and the ventricles. Cardiac arrhythmias like atrial and ventricular fibrillation (AF,VF) or ventricular tachycardia (VT) are caused by disruptions and instabilities of these electrical excitations, that lead to the emergence of rotating waves (VT) and turbulent wave patterns (AF,VF). Numerous simulation and experimental studies during the last 20 years have addressed these topics. In this review we focus on the nonlinear dynamics of wave propagation in the heart with an emphasis on the theory of pulses, spirals and scroll waves and their instabilities in excitable media with applications to cardiac modeling. After an introduction into electrophysiological models for action potential propagation, the modeling and analysis of spatiotemporal alternans, spiral and scroll meandering, spiral breakup and scroll wave instabilities like negative line tension and sproing are reviewed in depth and discussed with emphasis on their impact for cardiac arrhythmias.
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Affiliation(s)
- Sergio Alonso
- Physikalisch-Technische Bundesanstalt, Abbestr. 2-12 10587, Berlin, Germany. Department of Physics, Universitat Politècnica de Catalunya, Av. Dr. Marañón 44, E-08028 Barcelona, Spain
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23
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Kharaziha M, Memic A, Akbari M, Brafman DA, Nikkhah M. Nano-Enabled Approaches for Stem Cell-Based Cardiac Tissue Engineering. Adv Healthc Mater 2016; 5:1533-53. [PMID: 27199266 DOI: 10.1002/adhm.201600088] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/01/2016] [Indexed: 12/20/2022]
Abstract
Cardiac diseases are the most prevalent causes of mortality in the world, putting a major economic burden on global healthcare system. Tissue engineering strategies aim at developing efficient therapeutic approaches to overcome the current challenges in prolonging patients survival upon cardiac diseases. The integration of advanced biomaterials and stem cells has offered enormous promises for regeneration of damaged myocardium. Natural or synthetic biomaterials have been extensively used to deliver cells or bioactive molecules to the site of injury in heart. Additionally, nano-enabled approaches (e.g., nanomaterials, nanofeatured surfaces) have been instrumental in developing suitable scaffolding biomaterials and regulating stem cells microenvironment to achieve functional therapeutic outcomes. This review article explores tissue engineering strategies, which have emphasized on the use of nano-enabled approaches in combination with stem cells for regeneration and repair of injured myocardium upon myocardial infarction (MI). Primarily a wide range of biomaterials, along with different types of stem cells, which have utilized in cardiac tissue engineering will be presented. Then integration of nanomaterials and surface nanotopographies with biomaterials and stem cells for myocardial regeneration will be presented. The advantages and challenges of these approaches will be reviewed and future perspective will be discussed.
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Affiliation(s)
- Mahshid Kharaziha
- Biomaterials Research Group; Department of Materials Engineering; Isfahan University of Technology; Isfahan 8415683111 Iran
| | - Adnan Memic
- Center of Nanotechnology; King Abdulaziz University; Jeddah 21589 Saudi Arabia
| | - Mohsen Akbari
- Department of Mechanical Engineering; University of Victoria; Victoria BC Canada
| | - David A. Brafman
- School of Biological and Health Systems Engineering (SBHSE) Harington; Bioengineering Program; Arizona State University; Tempe Arizona 85287 USA
| | - Mehdi Nikkhah
- School of Biological and Health Systems Engineering (SBHSE) Harington; Bioengineering Program; Arizona State University; Tempe Arizona 85287 USA
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24
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Shensong Yangxin (SSYX) ameliorates disordered excitation transmission by suppressing cardiac collagen hyperplasia in rabbits with chronic myocardial infarction. ACTA ACUST UNITED AC 2016; 36:162-167. [PMID: 27072956 DOI: 10.1007/s11596-016-1560-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/26/2016] [Indexed: 01/24/2023]
Abstract
The traditional Chinese medicine Shensong Yangxin (SSYX) can improve the clinical symptoms of arrhythmia in an integrated manner. This study aimed to investigate the electrophysiological effect of SSYX on the hearts of myocardial-infarcted rabbits and further explore the mechanism by which SSYX alleviates myocardial fibrosis. Myocardial infarction (MI) was established in rabbits by ligation of the left circumflex coronary. The rabbits were treated with SSYX (0.5 g/kg/d) or saline for 8 weeks by oral administration. Microelectrode array (MEA) technology was used in vivo for extracellular electrophysiological recordings of the infarct border zone. Masson's trichrome staining was used to observe myocardial fibrosis. Western blotting was performed to evaluate the protein expression levels of collagen I (COL I) and collagen III (COL III). Quantitative real-time polymerase chain reaction (real-time PCR) was performed to evaluate the TGF-β1 and MMP-2 mRNA expression levels. The results showed that the total activation time (TAT) and the dispersion of TAT were significantly increased and the excitation propagation markedly disordered after MI. SSYX could significantly decrease TAT and the dispersion of TAT, and significantly ameliorate the chaotic spread pattern of excitation. Furthermore, SSYX treatment could significantly decrease COL I and COL III protein levels and down-regulate TGF-β1 and MMP-2 mRNA expression levels in MI rabbits. It was concluded that SSYX may ameliorate cardiac electrophysiological abnormalities in infarcted hearts by decreasing the protein levels of COL I and COL III, down-regulating the mRNA expression levels of TGF-β1 and MMP2, and thereby reducing adverse cardiac remodeling.
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25
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Ciaccio EJ, Coromilas J, Wit AL, Peters NS, Garan H. Formation of reentrant circuits in the mid-myocardial infarct border zone. Comput Biol Med 2016; 71:205-13. [DOI: 10.1016/j.compbiomed.2016.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/19/2016] [Accepted: 02/08/2016] [Indexed: 11/28/2022]
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26
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Neo M, Morris DG, Kuklik P, Lau DH, Dimitri H, Lim WW, Sanders P, Saint DA. Simultaneous conduction mapping and intracellular membrane potential recording in isolated atria. Can J Physiol Pharmacol 2015; 94:563-9. [PMID: 26771118 DOI: 10.1139/cjpp-2015-0194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a novel approach for simultaneously determining regional differences in action potential (AP) morphology and tissue electrophysiological properties in isolated atria. The epicardial surface of rat atrial preparations was placed in contact with a multi-electrode array (9 × 10 silver chloride electrodes, 0.1 mm diameter and 0.1 mm pitch). A glass microelectrode (100 MΩ) was simultaneously inserted into the endocardial surface to record intracellular AP from either of 2 regions (A, B) during pacing from 2 opposite corners of the tissue. AP duration at 80% of repolarisation and its restitution curve was significantly different only in region A (p < 0.01) when AP was initiated at different stimulation sites. Alternans in AP duration and AP amplitude, and in conduction velocity were observed during 2 separate arrhythmic episodes. This approach of combining microelectrode array and intracellular membrane potential recording may provide new insights into arrhythmogenic mechanisms in animal models of cardiovascular disease.
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Affiliation(s)
- Melissa Neo
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - David G Morris
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Pawel Kuklik
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Dennis H Lau
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Hany Dimitri
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Wei-Wen Lim
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - David A Saint
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.,Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), School of Medical Sciences, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
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27
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Richardson WJ, Clarke SA, Quinn TA, Holmes JW. Physiological Implications of Myocardial Scar Structure. Compr Physiol 2015; 5:1877-909. [PMID: 26426470 DOI: 10.1002/cphy.c140067] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Once myocardium dies during a heart attack, it is replaced by scar tissue over the course of several weeks. The size, location, composition, structure, and mechanical properties of the healing scar are all critical determinants of the fate of patients who survive the initial infarction. While the central importance of scar structure in determining pump function and remodeling has long been recognized, it has proven remarkably difficult to design therapies that improve heart function or limit remodeling by modifying scar structure. Many exciting new therapies are under development, but predicting their long-term effects requires a detailed understanding of how infarct scar forms, how its properties impact left ventricular function and remodeling, and how changes in scar structure and properties feed back to affect not only heart mechanics but also electrical conduction, reflex hemodynamic compensations, and the ongoing process of scar formation itself. In this article, we outline the scar formation process following a myocardial infarction, discuss interpretation of standard measures of heart function in the setting of a healing infarct, then present implications of infarct scar geometry and structure for both mechanical and electrical function of the heart and summarize experiences to date with therapeutic interventions that aim to modify scar geometry and structure. One important conclusion that emerges from the studies reviewed here is that computational modeling is an essential tool for integrating the wealth of information required to understand this complex system and predict the impact of novel therapies on scar healing, heart function, and remodeling following myocardial infarction.
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Affiliation(s)
- William J Richardson
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Samantha A Clarke
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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28
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Determining six cardiac conductivities from realistically large datasets. Math Biosci 2015; 266:15-22. [DOI: 10.1016/j.mbs.2015.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 05/20/2015] [Accepted: 05/22/2015] [Indexed: 11/17/2022]
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29
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van Oosterom A. A comparison of electrocardiographic imaging based on two source types. Europace 2015; 16 Suppl 4:iv120-iv128. [PMID: 25362162 DOI: 10.1093/europace/euu268] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The aim of the study to compare the performance of two major source types involved in the imaging of the electric activity of the heart on the basis of potential differences observed on the thorax. The images depict either the timing of activation and repolarization of the myocardium or the potential field on a surface closely encompassing the myocardium. The depolarization and repolarization timing on a closed surface bounding the ventricular myocardium was derived from measured body surface potentials (BSPs), an MRI-based electric volume conductor model comprising the geometry of thorax, lungs, heart surface Sh, and cavities. The solution was constrained by using a template of the local transmembrane potentials (TMPs). The latter serve as the strength of the Equivalent Double Layer (EDL) source model (SM), which was used to compute the potential field on Sh (epicardium and endocardium). The second SM is the potential distribution on the epicardium Sp, referred to here as the Equivalent Potential Distribution (EPD). Its strength was estimated directly from the BSPs. The inflection points of the estimated electrograms (ELGs) were taken as markers of the timing of local depolarization and repolarization. The endocardial potential fields estimated using both sources exhibited qualitative similarity, as did the ELGs. With reference to the one generated by the EDL source, the magnitude of the estimated endocardial EPD field was smaller, the downslopes of the ELGs were lower. The timing of depolarization estimated from the EDL-based ELGs was highly correlated with those of the TMP templates, the EPD-based correlation was lower. For the repolarization timing the corresponding test values indicated an insufficient similarity. The EDL- and EPD-based source variants deserve to be studied alongside each other in the future development of electrocardiographic imaging.
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31
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Optimization of catheter ablation of atrial fibrillation: insights gained from clinically-derived computer models. Int J Mol Sci 2015; 16:10834-54. [PMID: 25984605 PMCID: PMC4463678 DOI: 10.3390/ijms160510834] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/03/2015] [Accepted: 05/06/2015] [Indexed: 12/04/2022] Open
Abstract
Atrial fibrillation (AF) is the most common heart rhythm disturbance, and its treatment is an increasing economic burden on the health care system. Despite recent intense clinical, experimental and basic research activity, the treatment of AF with current antiarrhythmic drugs and catheter/surgical therapies remains limited. Radiofrequency catheter ablation (RFCA) is widely used to treat patients with AF. Current clinical ablation strategies are largely based on atrial anatomy and/or substrate detected using different approaches, and they vary from one clinical center to another. The nature of clinical ablation leads to ambiguity regarding the optimal patient personalization of the therapy partly due to the fact that each empirical configuration of ablation lines made in a patient is irreversible during one ablation procedure. To investigate optimized ablation lesion line sets, in silico experimentation is an ideal solution. 3D computer models give us a unique advantage to plan and assess the effectiveness of different ablation strategies before and during RFCA. Reliability of in silico assessment is ensured by inclusion of accurate 3D atrial geometry, realistic fiber orientation, accurate fibrosis distribution and cellular kinetics; however, most of this detailed information in the current computer models is extrapolated from animal models and not from the human heart. The predictive power of computer models will increase as they are validated with human experimental and clinical data. To make the most from a computer model, one needs to develop 3D computer models based on the same functionally and structurally mapped intact human atria with high spatial resolution. The purpose of this review paper is to summarize recent developments in clinically-derived computer models and the clinical insights they provide for catheter ablation.
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32
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Peiker C, Pott C, Eckardt L, Kelm M, Shin DI, Willems S, Meyer C. Dual atrioventricular nodal non-re-entrant tachycardia. Europace 2015; 18:332-9. [DOI: 10.1093/europace/euv056] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/19/2015] [Indexed: 11/14/2022] Open
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33
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Hooks DA, Berte B, Yamashita S, Mahida S, Sellal JM, Aljefairi N, Frontera A, Derval N, Denis A, Hocini M, Haïssaguerre M, Jaïs P, Sacher F. New strategies for ventricular tachycardia and ventricular fibrillation ablation. Expert Rev Cardiovasc Ther 2015; 13:263-76. [DOI: 10.1586/14779072.2015.1009039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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34
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Wang K, Lee P, Mirams GR, Sarathchandra P, Borg TK, Gavaghan DJ, Kohl P, Bollensdorff C. Cardiac tissue slices: preparation, handling, and successful optical mapping. Am J Physiol Heart Circ Physiol 2015; 308:H1112-25. [PMID: 25595366 PMCID: PMC4551126 DOI: 10.1152/ajpheart.00556.2014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/14/2015] [Indexed: 01/28/2023]
Abstract
Cardiac tissue slices are becoming increasingly popular as a model system for cardiac electrophysiology and pharmacology research and development. Here, we describe in detail the preparation, handling, and optical mapping of transmembrane potential and intracellular free calcium concentration transients (CaT) in ventricular tissue slices from guinea pigs and rabbits. Slices cut in the epicardium-tangential plane contained well-aligned in-slice myocardial cell strands (“fibers”) in subepicardial and midmyocardial sections. Cut with a high-precision slow-advancing microtome at a thickness of 350 to 400 μm, tissue slices preserved essential action potential (AP) properties of the precutting Langendorff-perfused heart. We identified the need for a postcutting recovery period of 36 min (guinea pig) and 63 min (rabbit) to reach 97.5% of final steady-state values for AP duration (APD) (identified by exponential fitting). There was no significant difference between the postcutting recovery dynamics in slices obtained using 2,3-butanedione 2-monoxime or blebistatin as electromechanical uncouplers during the cutting process. A rapid increase in APD, seen after cutting, was caused by exposure to ice-cold solution during the slicing procedure, not by tissue injury, differences in uncouplers, or pH-buffers (bicarbonate; HEPES). To characterize intrinsic patterns of CaT, AP, and conduction, a combination of multipoint and field stimulation should be used to avoid misinterpretation based on source-sink effects. In summary, we describe in detail the preparation, mapping, and data analysis approaches for reproducible cardiac tissue slice-based investigations into AP and CaT dynamics.
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Affiliation(s)
- Ken Wang
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Peter Lee
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, United Kingdom
| | - Gary R Mirams
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Padmini Sarathchandra
- Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom
| | - Thomas K Borg
- Department of Regenerative Medicine and Cell Biology, University of South Carolina School of Medicine, Charleston, South Carolina; and
| | - David J Gavaghan
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Peter Kohl
- Department of Computer Science, University of Oxford, Oxford, United Kingdom; Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom
| | - Christian Bollensdorff
- Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom; Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
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35
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Reed A, Kohl P, Peyronnet R. Molecular candidates for cardiac stretch-activated ion channels. Glob Cardiol Sci Pract 2014; 2014:9-25. [PMID: 25405172 PMCID: PMC4220428 DOI: 10.5339/gcsp.2014.19] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/08/2014] [Indexed: 01/20/2023] Open
Abstract
The heart is a mechanically-active organ that dynamically senses its own mechanical environment. This environment is constantly changing, on a beat-by-beat basis, with additional modulation by respiratory activity and changes in posture or physical activity, and further overlaid with more slowly occurring physiological (e.g. pregnancy, endurance training) or pathological challenges (e.g. pressure or volume overload). Far from being a simple pump, the heart detects changes in mechanical demand and adjusts its performance accordingly, both via heart rate and stroke volume alteration. Many of the underlying regulatory processes are encoded intracardially, and are thus maintained even in heart transplant recipients. Over the last three decades, molecular substrates of cardiac mechanosensitivity have gained increasing recognition in the scientific and clinical communities. Nonetheless, the processes underlying this phenomenon are still poorly understood. Stretch-activated ion channels (SAC) have been identified as one contributor to mechanosensitive autoregulation of the heartbeat. They also appear to play important roles in the development of cardiac pathologies – most notably stretch-induced arrhythmias. As recently discovered, some established cardiac drugs act, in part at least, via mechanotransduction pathways suggesting SAC as potential therapeutic targets. Clearly, identification of the molecular substrate of cardiac SAC is of clinical importance and a number of candidate proteins have been identified. At the same time, experimental studies have revealed variable–and at times contrasting–results regarding their function. Further complication arises from the fact that many ion channels that are not classically defined as SAC, including voltage and ligand-gated ion channels, can respond to mechanical stimulation. Here, we summarise what is known about the molecular substrate of the main candidates for cardiac SAC, before identifying potential further developments in this area of translational research.
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Affiliation(s)
- Alistair Reed
- Medical Sciences Division, University of Oxford, United Kingdom
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36
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Kohl P, Gourdie RG. Fibroblast-myocyte electrotonic coupling: does it occur in native cardiac tissue? J Mol Cell Cardiol 2014; 70:37-46. [PMID: 24412581 PMCID: PMC4001130 DOI: 10.1016/j.yjmcc.2013.12.024] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 11/05/2022]
Abstract
Heterocellular electrotonic coupling between cardiac myocytes and non-excitable connective tissue cells has been a long-established and well-researched fact in vitro. Whether or not such coupling exists in vivo has been a matter of considerable debate. This paper reviews the development of experimental insight and conceptual views on this topic, describes evidence in favour of and against the presence of such coupling in native myocardium, and identifies directions for further study needed to resolve the riddle, perhaps less so in terms of principal presence which has been demonstrated, but undoubtedly in terms of extent, regulation, patho-physiological context, and actual relevance of cardiac myocyte–non-myocyte coupling in vivo. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium." Electrical coupling of cardiomyocytes and fibroblasts is well-established in vitro Whether such hetero-cellular coupling exists in vivo has been a matter of debate We review the development of experimental and conceptual insight into the topic Conclusion 1: hetero-cellular coupling in heart tissue has been shown in principle Conclusion 2: extent, regulation, context, and relevance remain to be established
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Affiliation(s)
- Peter Kohl
- Imperial College, National Heart and Lung Institute, Harefield Hospital, UB6 9JH, UK.
| | - Robert G Gourdie
- Virginia Tech, Carilion Research Institute, 2 Riverside Circle, Roanoke, VA 24015, USA
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37
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