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De Coster T, Teplenin AS, Feola I, Bart CI, Ramkisoensing AA, den Ouden BL, Ypey DL, Trines SA, Panfilov AV, Zeppenfeld K, de Vries AAF, Pijnappels DA. 'Trapped re-entry' as source of acute focal atrial arrhythmias. Cardiovasc Res 2024; 120:249-261. [PMID: 38048392 PMCID: PMC10939464 DOI: 10.1093/cvr/cvad179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 08/21/2023] [Accepted: 10/07/2023] [Indexed: 12/06/2023] Open
Abstract
AIMS Diseased atria are characterized by functional and structural heterogeneities, adding to abnormal impulse generation and propagation. These heterogeneities are thought to lie at the origin of fractionated electrograms recorded during sinus rhythm (SR) in atrial fibrillation (AF) patients and are assumed to be involved in the onset and perpetuation (e.g. by re-entry) of this disorder. The underlying mechanisms, however, remain incompletely understood. Here, we tested whether regions of dense fibrosis could create an electrically isolated conduction pathway (EICP) in which re-entry could be established via ectopy and local block to become 'trapped'. We also investigated whether this could generate local fractionated electrograms and whether the re-entrant wave could 'escape' and cause a global tachyarrhythmia due to dynamic changes at a connecting isthmus. METHODS AND RESULTS To precisely control and explore the geometrical properties of EICPs, we used light-gated depolarizing ion channels and patterned illumination for creating specific non-conducting regions in silico and in vitro. Insight from these studies was used for complementary investigations in virtual human atria with localized fibrosis. We demonstrated that a re-entrant tachyarrhythmia can exist locally within an EICP with SR prevailing in the surrounding tissue and identified conditions under which re-entry could escape from the EICP, thereby converting a local latent arrhythmic source into an active driver with global impact on the heart. In a realistic three-dimensional model of human atria, unipolar epicardial pseudo-electrograms showed fractionation at the site of 'trapped re-entry' in coexistence with regular SR electrograms elsewhere in the atria. Upon escape of the re-entrant wave, acute arrhythmia onset was observed. CONCLUSIONS Trapped re-entry as a latent source of arrhythmogenesis can explain the sudden onset of focal arrhythmias, which are able to transgress into AF. Our study might help to improve the effectiveness of ablation of aberrant cardiac electrical signals in clinical practice.
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Affiliation(s)
- Tim De Coster
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Alexander S Teplenin
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Iolanda Feola
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Cindy I Bart
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Arti A Ramkisoensing
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Bram L den Ouden
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Dirk L Ypey
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Serge A Trines
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Alexander V Panfilov
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
- Department of Physics and Astronomy, Ghent University, 9000 Ghent, Belgium
- Biomed Laboratory, Ural Federal University, 620002 Ekaterinburg, Russia
- World-Class Research Center ‘Digital Biodesign and Personalized Healthcare’, I. M. Sechenov First Moscow State Medical University, 119146 Moscow, Russia
| | - Katja Zeppenfeld
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, PO 9600, 2333 ZA Leiden, The Netherlands
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Chi J, Wu N, Li P, Hu J, Cai H, Lin C, Lai Y, Yang H, Huang J, Li M, Xu L. Hygrothermal stress increases malignant arrhythmias susceptibility by inhibiting the LKB1-AMPK-Cx43 pathway. Sci Rep 2024; 14:5010. [PMID: 38424223 PMCID: PMC10904738 DOI: 10.1038/s41598-024-55804-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 02/27/2024] [Indexed: 03/02/2024] Open
Abstract
High mortality due to hygrothermal stress during heat waves is mostly linked to cardiovascular malfunction, the most serious of which are malignant arrhythmias. However, the mechanism associated with hygrothermal stress leading to malignant arrhythmias remains unclear. The energy metabolism regulated by liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) and the electrical signaling based on gap junction protein, connexin43 (Cx43), plays important roles in the development of cardiac arrhythmias. In order to investigate whether hygrothermal stress induces arrhythmias via the LKB1-AMPK-Cx43 pathway, Sprague-Dawley rats were exposed to high temperature and humidity for constructing the hygrothermal stress model. A final choice of 40 °C and 85% humidity was made by pre-exploration based on different gradient environmental conditions with reference to arrhythmia event-inducing stability and risk of sudden death. Then, the incidence of arrhythmic events, as well as the expression, phosphorylation at Ser368, and distribution of Cx43 in the myocardium, were examined. Meanwhile, the adenosine monophosphate-activated protein kinase activator, Acadesine, was also administered to investigate the role played by AMPK in the process. Our results showed that hygrothermal stress induced malignant arrhythmias such as ventricular tachycardia, ventricular fibrillation, and severe atrioventricular block. Besides, hygrothermal stress decreased the phosphorylation of Cx43 at Ser368, induced proarrhythmic redistribution of Cx43 from polar to lateral sides of the cardiomyocytes, and also caused LKB1 and phosphorylated-AMPK expression to be less abundant. While, pretreatment with Acadesine significantly actived the LKB1-AMPK-Cx43 pathway and thus ameliorated malignant arrhythmias, indicating that the hygrothermal stress-induced arrhythmias is associated with the redistribution of gap junctions in cardiomyocytes and the organism's energy metabolism.
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Affiliation(s)
- Jianing Chi
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China
- Guangzhou Key Laboratory of Cardiac Rehabilitation, Guangzhou, China
| | - Ningxia Wu
- Graduate School, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Pengfei Li
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
| | - Jiaman Hu
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
- School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China
| | - Hua Cai
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
- Graduate School, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Cailong Lin
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China
- School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yingying Lai
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China
- School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China
| | - Han Yang
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
| | - Jianyu Huang
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China
| | - Min Li
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China
| | - Lin Xu
- The First School of Clinical Medicine, Southern Medical University, Guangzhou, China.
- Department of Geriatric Cardiology, General Hospital of Southern Theater Command, Guangzhou, China.
- Branch of National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Guangzhou, China.
- Guangzhou Key Laboratory of Cardiac Rehabilitation, Guangzhou, China.
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3
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Colman MA, Benson AP. A simple approach for image-based modelling of the heart that enables robust simulation of highly heterogeneous electrical excitation. Sci Rep 2023; 13:15119. [PMID: 37704647 PMCID: PMC10499818 DOI: 10.1038/s41598-023-39244-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/21/2023] [Indexed: 09/15/2023] Open
Abstract
Remodelling of cardiac tissue structure, including intercellular electrical coupling, is a major determinant of the complex and heterogeneous excitation patterns associated with cardiac arrhythmias. Evaluation of the precise mechanisms by which local tissue structure determines global arrhythmic excitation patterns is a major challenge that may be critically important for the development of effective treatment strategies. Computational modelling is a key tool in the study of cardiac arrhythmias, yet the established approaches for organ-scale modelling are unsuitable to capture the impact of local conduction heterogeneities; a novel approach is required to provide this multi-scale mechanistic insight. We present a fundamentally simple yet powerful approach to simulate electrical excitation in highly heterogeneous whole-heart models that exploits the underlying discreteness of the myocardium. Preliminary simulations demonstrate that this approach can capture lower conduction velocities and reproduce wave breakdown and the development of re-entry in a range of conditions.
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Affiliation(s)
- Michael A Colman
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK.
| | - Alan P Benson
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK
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Xu L, Khoshknab M, Berger RD, Chrispin J, Dixit S, Santangeli P, Callans D, Marchlinski FE, Zimmerman SL, Han Y, Trayanova N, Desjardins B, Nazarian S. Lipomatous Metaplasia Enables Ventricular Tachycardia by Reducing Current Loss Within the Protected Corridor. JACC Clin Electrophysiol 2022; 8:1274-1285. [PMID: 36266004 PMCID: PMC11148646 DOI: 10.1016/j.jacep.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/23/2022] [Accepted: 07/01/2022] [Indexed: 11/19/2022]
Abstract
BACKGROUND Post-myocardial infarction ventricular tachycardia (VT) is due to re-entry through surviving conductive myocardial corridors across infarcted tissue. However, not all conductive corridors participate in re-entry. OBJECTIVES This study sought to test the hypothesis that critical VT corridors are more likely to traverse near lipomatous metaplasia (LM) and that current loss is reduced during impulse propagation through such corridors. METHODS Among 30 patients in the Prospective 2-center INFINITY (Intra-Myocardial Fat Deposition and Ventricular Tachycardia in Cardiomyopathy) study, potential VT-viable corridors within myocardial scar or LM were computed from late gadolinium enhancement cardiac magnetic resonance images. Because late gadolinium enhancement highlights both scar and LM, LM was distinguished from scar by using computed tomography. The SD of the current along each corridor was measured. RESULTS Scar exhibited lower impedance than LM (median Z-score -0.22 [IQR: -0.84 to 0.35] vs -0.07 [IQR: -0.67 to 0.54]; P < 0.001). Among all 381 corridors, 84 were proven to participate in VT re-entry circuits, 83 (99%) of which traversed or were adjacent to LM. In comparison, only 13 (4%) non-VT corridors were adjacent to LM. Critical corridors adjacent to LM displayed lower SD of current compared with noncritical corridors through scar but distant from LM (2.0 [IQR: 1.0 to 3.4] μA vs 8.4 [IQR: 5.5 to 12.8] μA; P < 0.001). CONCLUSIONS Corridors critical to VT circuitry traverse infarcted tissue through or near LM. This association is likely mediated by increased regional resistance and reduced current loss as impulses traverse corridors adjacent to LM.
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Affiliation(s)
- Lingyu Xu
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Mirmilad Khoshknab
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ronald D Berger
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA; Department of Cardiology, Johns Hopkins University, Baltimore Maryland, USA
| | - Jonathan Chrispin
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA; Department of Cardiology, Johns Hopkins University, Baltimore Maryland, USA
| | - Sanjay Dixit
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Pasquale Santangeli
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - David Callans
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Francis E Marchlinski
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Stefan L Zimmerman
- Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore Maryland, USA
| | - Yuchi Han
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Natalia Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Benoit Desjardins
- Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Saman Nazarian
- Cardiovascular Medicine Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
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Junge S, Schmieder F, Sasse P, Czarske J, Torres-Mapa ML, Heisterkamp A. Holographic optogenetic stimulation with calcium imaging as an all optical tool for cardiac electrophysiology. JOURNAL OF BIOPHOTONICS 2022; 15:e202100352. [PMID: 35397155 DOI: 10.1002/jbio.202100352] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/25/2022] [Accepted: 04/06/2022] [Indexed: 06/14/2023]
Abstract
All optical approaches to control and read out the electrical activity in a cardiac syncytium can improve our understanding of cardiac electrophysiology. Here, we demonstrate optogenetic stimulation of cardiomyocytes with high spatial precision using light foci generated with a ferroelectric spatial light modulator. Computer generated holograms binarized by bidirectional error diffusion create multiple foci with more even intensity distribution compared with thresholding approach. We evoke the electrical activity of cardiac HL1 cells expressing the channelrhodopsin-2 variant, ChR2(H134R) using single and multiple light foci and at the same time visualize the action potential using a calcium sensitive indicator called Cal-630. We show that localized regions in the cardiac monolayer can be stimulated enabling us to initiate signal propagation from a precise location. Furthermore, we demonstrate that probing the cardiac cells with multiple light foci enhances the excitability of the cardiac network. This approach opens new applications in manipulating and visualizing the electrical activity in a cardiac syncytium.
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Affiliation(s)
- Sebastian Junge
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Felix Schmieder
- Faculty of Electrical and Computer Engineering, Laboratory of Measurement and Sensor System Technique and Competence Center Biomedical Computational Laser Systems (BIOLAS), TU Dresden, Dresden, Germany
| | - Philipp Sasse
- Medical Faculty, Institute of Physiology I, University of Bonn, Bonn, Germany
| | - Jürgen Czarske
- Faculty of Electrical and Computer Engineering, Laboratory of Measurement and Sensor System Technique and Competence Center Biomedical Computational Laser Systems (BIOLAS), TU Dresden, Dresden, Germany
- Faculty of Physics, School of Science and Excellence Cluster Physics of Life, TU Dresden, Dresden, Germany
| | - Maria Leilani Torres-Mapa
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
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Billur D, Olgar Y, Turan B. Intracellular Redistribution of Left Ventricular Connexin 43 Contributes to the Remodeling of Electrical Properties of the Heart in Insulin-resistant Elderly Rats. J Histochem Cytochem 2022; 70:447-462. [PMID: 35608408 DOI: 10.1369/00221554221101661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The correlation between long-QT and connexin 43 (Cx43) status and localization in elderly rats was determined to demonstrate a correlation between insulin resistance (I-R), ischemia-reperfusion, aging, and heart dysfunction. Male Wistar rats are grouped as 24-month-old rats (Aged-group), those with metabolic syndrome (8 months old; MetS-group), or controls (8 months old; Con-group). Both experimental groups have long-QT and low heart rate. Immunohistochemical imaging and quantification showed marked decreases in Cx43 staining of intercalated disc with less localizations in the Aged-group and MetS-group. The lateralization of Cx43 on longitudinal cell membrane was significantly high in the MetS-group than in the Con-group with no significant change in the Aged-group. Its significant cytoplasmic internalization was higher in the Aged-group than in the MetS-group. There were marked decreases in phospho-Cx43 (pCx43) staining of intercalated disc with less localizations in both groups than in the Con-group. Furthermore, lateralization of pCx43 was significantly low in the Aged-group and MetS-group, whereas there were no significant changes in the cytoplasmic internalization of both groups compared with the Con-group. Furthermore, the ratio of pCx43 to Cx43 was significantly small in both groups. We determined increases in RhoA and endothelin-1 in both groups, further supporting decreases in pCx43. Our data indicate the important role of I-R on long-QT in aging heart through alterations in both Cx43 protein level and localizations, leading to an abnormal spreading of ventricular repolarization in I-R heart.
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Affiliation(s)
| | | | - Belma Turan
- Department of Biophysics.,Faculty of Medicine, Ankara University, Ankara, Turkey, and Department of Biophysics, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey
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Mechanisms Underlying Antiarrhythmic Properties of Cardioprotective Agents Impacting Inflammation and Oxidative Stress. Int J Mol Sci 2022; 23:ijms23031416. [PMID: 35163340 PMCID: PMC8835881 DOI: 10.3390/ijms23031416] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/21/2022] [Accepted: 01/25/2022] [Indexed: 01/27/2023] Open
Abstract
The prevention of cardiac life-threatening ventricular fibrillation and stroke-provoking atrial fibrillation remains a serious global clinical issue, with ongoing need for novel approaches. Numerous experimental and clinical studies suggest that oxidative stress and inflammation are deleterious to cardiovascular health, and can increase heart susceptibility to arrhythmias. It is quite interesting, however, that various cardio-protective compounds with antiarrhythmic properties are potent anti-oxidative and anti-inflammatory agents. These most likely target the pro-arrhythmia primary mechanisms. This review and literature-based analysis presents a realistic view of antiarrhythmic efficacy and the molecular mechanisms of current pharmaceuticals in clinical use. These include the sodium-glucose cotransporter-2 inhibitors used in diabetes treatment, statins in dyslipidemia and naturally protective omega-3 fatty acids. This approach supports the hypothesis that prevention or attenuation of oxidative and inflammatory stress can abolish pro-arrhythmic factors and the development of an arrhythmia substrate. This could prove a powerful tool of reducing cardiac arrhythmia burden.
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Verheule S, Schotten U. Electrophysiological Consequences of Cardiac Fibrosis. Cells 2021; 10:cells10113220. [PMID: 34831442 PMCID: PMC8625398 DOI: 10.3390/cells10113220] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/09/2021] [Accepted: 11/12/2021] [Indexed: 12/27/2022] Open
Abstract
For both the atria and ventricles, fibrosis is generally recognized as one of the key determinants of conduction disturbances. By definition, fibrosis refers to an increased amount of fibrous tissue. However, fibrosis is not a singular entity. Various forms can be distinguished, that differ in distribution: replacement fibrosis, endomysial and perimysial fibrosis, and perivascular, endocardial, and epicardial fibrosis. These different forms typically result from diverging pathophysiological mechanisms and can have different consequences for conduction. The impact of fibrosis on propagation depends on exactly how the patterns of electrical connections between myocytes are altered. We will therefore first consider the normal patterns of electrical connections and their regional diversity as determinants of propagation. Subsequently, we will summarize current knowledge on how different forms of fibrosis lead to a loss of electrical connectivity in order to explain their effects on propagation and mechanisms of arrhythmogenesis, including ectopy, reentry, and alternans. Finally, we will discuss a histological quantification of fibrosis. Because of the different forms of fibrosis and their diverging effects on electrical propagation, the total amount of fibrosis is a poor indicator for the effect on conduction. Ideally, an assessment of cardiac fibrosis should exclude fibrous tissue that does not affect conduction and differentiate between the various types that do; in this article, we highlight practical solutions for histological analysis that meet these requirements.
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Long Y, Li Y, Lu Z. Atrioventricular accessory pathway unmasked by heart valve replacement. Ann Noninvasive Electrocardiol 2021; 27:e12911. [PMID: 34783420 PMCID: PMC9107084 DOI: 10.1111/anec.12911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/27/2021] [Accepted: 10/17/2021] [Indexed: 11/28/2022] Open
Abstract
A 50‐year‐old male patient with a history of severe valvular regurgitation underwent mitral and aortic valve replacement surgery 3 months ago. Preoperative 12‐lead electrocardiogram presented atrial flutter (AFL) and atrial fibrillation. AFL complicated with ventricular pre‐excitation was observed on current admission. The potential mechanisms underlying these changes were considered multifaceted, and valve replacement procedure may be a rare incentive factor.
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Affiliation(s)
- Yanli Long
- Department of Cardiothoracic Surgery, Wuhan Asia Heart Hospital Affiliated to Wuhan University of Science and Technology, Wuhan, China
| | - Yi Li
- Division of Cardiology, Department of Internal Medicine, Institute of Myocardial Injury and Repair, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Zhibing Lu
- Division of Cardiology, Department of Internal Medicine, Institute of Myocardial Injury and Repair, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
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10
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Han B, Trew ML, Zgierski-Johnston CM. Cardiac Conduction Velocity, Remodeling and Arrhythmogenesis. Cells 2021; 10:cells10112923. [PMID: 34831145 PMCID: PMC8616078 DOI: 10.3390/cells10112923] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/14/2021] [Accepted: 10/22/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiac electrophysiological disorders, in particular arrhythmias, are a key cause of morbidity and mortality throughout the world. There are two basic requirements for arrhythmogenesis: an underlying substrate and a trigger. Altered conduction velocity (CV) provides a key substrate for arrhythmogenesis, with slowed CV increasing the probability of re-entrant arrhythmias by reducing the length scale over which re-entry can occur. In this review, we examine methods to measure cardiac CV in vivo and ex vivo, discuss underlying determinants of CV, and address how pathological variations alter CV, potentially increasing arrhythmogenic risk. Finally, we will highlight future directions both for methodologies to measure CV and for possible treatments to restore normal CV.
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Affiliation(s)
- Bo Han
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, 79110 Freiburg im Breisgau, Germany;
- Faculty of Medicine, University of Freiburg, 79110 Freiburg im Breisgau, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Department of Cardiovascular Surgery, The Fourth People’s Hospital of Jinan, 250031 Jinan, China
| | - Mark L. Trew
- Auckland Bioengineering Institute, University of Auckland, Auckland 1010, New Zealand;
| | - Callum M. Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, 79110 Freiburg im Breisgau, Germany;
- Faculty of Medicine, University of Freiburg, 79110 Freiburg im Breisgau, Germany
- Correspondence:
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11
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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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12
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Remodeling of Cardiac Gap Junctional Cell-Cell Coupling. Cells 2021; 10:cells10092422. [PMID: 34572071 PMCID: PMC8465208 DOI: 10.3390/cells10092422] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 12/29/2022] Open
Abstract
The heart works as a functional syncytium, which is realized via cell-cell coupling maintained by gap junction channels. These channels connect two adjacent cells, so that action potentials can be transferred. Each cell contributes a hexameric hemichannel (=connexon), formed by protein subuntis named connexins. These hemichannels dock to each other and form the gap junction channel. This channel works as a low ohmic resistor also allowing the passage of small molecules up to 1000 Dalton. Connexins are a protein family comprising of 21 isoforms in humans. In the heart, the main isoforms are Cx43 (the 43 kDa connexin; ubiquitous), Cx40 (mostly in atrium and specific conduction system), and Cx45 (in early developmental states, in the conduction system, and between fibroblasts and cardiomyocytes). These gap junction channels are mainly located at the polar region of the cardiomyocytes and thus contribute to the anisotropic pattern of cardiac electrical conductivity. While in the beginning the cell–cell coupling was considered to be static, similar to an anatomically defined structure, we have learned in the past decades that gap junctions are also subject to cardiac remodeling processes in cardiac disease such as atrial fibrillation, myocardial infarction, or cardiomyopathy. The underlying remodeling processes include the modulation of connexin expression by e.g., angiotensin, endothelin, or catecholamines, as well as the modulation of the localization of the gap junctions e.g., by the direction and strength of local mechanical forces. A reduction in connexin expression can result in a reduced conduction velocity. The alteration of gap junction localization has been shown to result in altered pathways of conduction and altered anisotropy. In particular, it can produce or contribute to non-uniformity of anisotropy, and thereby can pre-form an arrhythmogenic substrate. Interestingly, these remodeling processes seem to be susceptible to certain pharmacological treatment.
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Oknińska M, Paterek A, Bierła J, Czarnowska E, Mączewski M, Mackiewicz U. Effect of age and sex on the incidence of ventricular arrhythmia in a rat model of acute ischemia. Biomed Pharmacother 2021; 142:111983. [PMID: 34392089 DOI: 10.1016/j.biopha.2021.111983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND The impact of sex and age on the arrhythmic susceptibility within the setting of acute ischemia is masked by the fact that acute coronary events result from coronary artery disease appearing with age much earlier among men than among women. METHODS AND RESULTS LAD ligation or sham operations were performed in rats of both sexes at the age 3 and 24 months. An ECG was recorded continuously for 6 h after the operation. The number of early and late premature ventricular beats (PVBs), episodes of ventricular tachycardia (VT) and fibrillation (VF), heart rate, QRS, QT and Tpeak-Tend duration were analysed. Epicardial action potentials were recorded in vivo, Ca2+ signaling was evaluated in isolated cardiomyocytes, fibrosis and connexin-43 expression and localization were measured in the septum. PVBs, VT and VF episodes are much more common in older males than in young males and females independently from their age. Fibrosis with varying intensity in different muscle layers, hypertrophy of cardiomyocytes, reduced number of gap junctions and their appearance on the lateral myocyte membrane, QT prolongation, increase transmural dispersion of repolarisation and a decreased function of SERCA2a may increase the propensity to arrhythmia within the setting of acute ischemia. CONCLUSION We show that the male sex, especially in case of older individuals is a strong predictor of increased arrhythmic susceptibility within the acute ischemia setting regardless of its impact on the occurrence of cardiovascular diseases. A personalized sex-dependent prevention treatment is needed to reduce the mortality in acute phases of myocardial infarction.
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Affiliation(s)
- Marta Oknińska
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Aleksandra Paterek
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Joanna Bierła
- Department of Pathology, The Children's Memorial Health Institute, Aleja Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Elżbieta Czarnowska
- Department of Pathology, The Children's Memorial Health Institute, Aleja Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Michał Mączewski
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Urszula Mackiewicz
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland.
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14
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Verzaal NJ, Massé S, Downar E, Nanthakumar K, Delhaas T, Prinzen FW. Exploring the cause of conduction delays in patients with repaired Tetralogy of Fallot. Europace 2021; 23:i105-i112. [PMID: 33751080 DOI: 10.1093/europace/euaa400] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 12/04/2020] [Indexed: 11/13/2022] Open
Abstract
AIMS Cardiac dyssynchrony in patients with repaired Tetralogy of Fallot (rToF) has been attributed to right bundle branch block (RBBB), fibrosis and/or the patches that are inserted during repair surgery. We aimed to investigate the basis of abnormal activation in rToF patients by mapping the electrical activation sequence during sinus rhythm (SR) and right ventricular (RV) pacing. METHODS AND RESULTS A total of 17 patients were studied [13 with rToF, 2 with left bundle branch block (LBBB), and 2 without RBBB or LBBB (non-BBB)] during medically indicated cardiac surgery. During SR and RV pacing, measurements were performed using 112-electrode RV endocardial balloons (rToF only) and biventricular epicardial sock arrays (four of the rToF and all non-rToF patients). During SR, functional lines of block occurred in five rToF patients, while RV pacing caused functional blocks in four rToF patients. The line of block persisted during both SR and RV pacing in only 2 out of 13 rToF patients. Compared to SR, RV pacing increased dispersion of septal activation, but not dispersion of endocardial and epicardial activation of the RV free wall. During pacing, RV and left ventricular activation dispersion in rToF patients were comparable to that of the non-rToF patients. CONCLUSION The results of the present study indicate that the delayed activation in the right ventricle of rToF patients is predominantly due to block(s) in the Purkinje system and that conduction in RV tissue is fairly normal.
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Affiliation(s)
- Nienke J Verzaal
- Department of Physiology, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada
| | - Eugene Downar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, University Health Network, 200 Elizabeth Street, Toronto, Ontario M5G 2C4, Canada
| | - Tammo Delhaas
- Department of Biomedical Engineering, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
| | - Frits W Prinzen
- Department of Physiology, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
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15
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Zhang L, Guo Y, Xiaokereti J, Cao G, Li H, Sun H, Li K, Zhou X, Tang B. Ganglionated Plexi Ablation Suppresses Chronic Obstructive Sleep Apnea-Related Atrial Fibrillation by Inhibiting Cardiac Autonomic Hyperactivation. Front Physiol 2021; 12:640295. [PMID: 33897452 PMCID: PMC8063039 DOI: 10.3389/fphys.2021.640295] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/02/2021] [Indexed: 12/19/2022] Open
Abstract
Background: Previous studies have reported that right pulmonary artery ganglionated plexi (GP) ablation could suppress the onset of atrial fibrillation (AF) associated with obstructive sleep apnea (OSA) within 1 h. Objective: This study aimed to investigate the effect of superior left GP (SLGP) ablation on AF in a chronic OSA canine model. Methods and Results: Fifteen beagles were randomly divided into three groups: control group (CTRL), OSA group (OSA), and OSA + GP ablation group (OSA + GP). All animals were intubated under general anesthesia, and ventilation-apnea events were subsequently repeated 4 h/day and 6 days/week for 12 weeks to establish a chronic OSA model. SLGP were ablated at the end of 8 weeks. SLGP ablation could attenuate the atrial effective refractory period (ERP) reduction and decrease ERP dispersion, the window of vulnerability, and AF inducibility. In addition, chronic OSA leads to left atrial (LA) enlargement, decreased left ventricular (LV) ejection fraction, glycogen deposition, increased necrosis, and myocardial fibrosis. SLGP ablation reduced the LA size and ameliorated LV dysfunction, while myocardial fibrosis could not be reversed. Additionally, SLGP ablation mainly reduced sympathovagal hyperactivity and post-apnea blood pressure and heart rate increases and decreased the expression of neural growth factor (NGF), tyrosine hydroxylase (TH), and choline acetyltransferase (CHAT) in the LA and SLGP. After SLGP ablation, the nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway, cholesterol metabolism pathway, and ferroptosis pathway were notably downregulated compared with OSA. Conclusions: SLGP ablation suppressed AF in a chronic OSA model by sympathovagal hyperactivity inhibition. However, there were no significant changes in myocardial fibrosis.
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Affiliation(s)
- Ling Zhang
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Yankai Guo
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Department of Cardiology, The Fifth Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Jiasuoer Xiaokereti
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Guiqiu Cao
- Department of Cardiology, The Fifth Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Hongliang Li
- Section of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Huaxin Sun
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Kai Li
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Xianhui Zhou
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Baopeng Tang
- Xinjiang Key Laboratory of Cardiac Electrophysiology and Cardiac Remodeling, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China.,Cardiac Pacing and Electrophysiology Department, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
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16
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Segovia-Roldan M, Diez ER, Pueyo E. Melatonin to Rescue the Aged Heart: Antiarrhythmic and Antioxidant Benefits. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:8876792. [PMID: 33791076 PMCID: PMC7984894 DOI: 10.1155/2021/8876792] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/16/2021] [Accepted: 01/23/2021] [Indexed: 12/19/2022]
Abstract
Aging comes with gradual loss of functions that increase the vulnerability to disease, senescence, and death. The mechanisms underlying these processes are linked to a prolonged imbalance between damage and repair. Damaging mechanisms include oxidative stress, mitochondrial dysfunction, chronodisruption, inflammation, and telomere attrition, as well as genetic and epigenetic alterations. Several endogenous tissue repairing mechanisms also decrease. These alterations associated with aging affect the entire organism. The most devastating manifestations involve the cardiovascular system and may lead to lethal cardiac arrhythmias. Together with structural remodeling, electrophysiological and intercellular communication alterations during aging predispose to arrhythmic events. Despite the knowledge on repairing mechanisms in the cardiovascular system, effective antiaging strategies able to reduce the risk of arrhythmias are still missing. Melatonin is a promising therapeutic candidate due to its pleiotropic actions. This indoleamine regulates chronobiology and endocrine physiology. Of relevance, melatonin is an antiaging, antioxidant, antiapoptotic, antiarrhythmic, immunomodulatory, and antiproliferative molecule. This review focuses on the protective effects of melatonin on age-induced cardiac functional and structural alterations, potentially becoming a new fountain of youth for the heart.
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Affiliation(s)
- Margarita Segovia-Roldan
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), I3A, Universidad de Zaragoza, IIS Aragón and CIBER-BBN, Spain
| | | | - Esther Pueyo
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), I3A, Universidad de Zaragoza, IIS Aragón and CIBER-BBN, Spain
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17
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Jiang LP, Lin JJ, Zhuang TP, Wang WW, Wu HZ, Zhang FL. Effects of ivabradine on ventricular electrophysiological remodeling after myocardial infarction in rats. Arch Med Sci 2020; 19:1497-1507. [PMID: 37732052 PMCID: PMC10507765 DOI: 10.5114/aoms.2020.101181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/22/2020] [Indexed: 09/22/2023] Open
Abstract
Introduction This study aims to investigate the effects of ivabradine (IVA) on ventricular electrophysiological remodeling after myocardial infarction (MI) in rats. Material and methods A total of 60 male Sprague-Dawley rats were randomly divided into five groups: an MI group, an IVA group, a metoprolol (MET) group, an IVA + MET group, and a sham group. After a four-week intervention, the ventricular electrophysiological parameters were detected by multichannel electrophysiological polygraph. Then, the morphological characteristics were evaluated using hematoxylin and eosin (H&E) and Masson's staining, and the expression of phosphorylated connexin 43 (p-Cx43) in the left ventricular wall was detected through immunohistochemistry and the Western blot test. Results The electrophysiological examination revealed that the induction rate and fatality rate of ventricular tachycardia (VT)/ventricular fibrillation (VF) were lower in both the IVA and the MET group, compared with the MI group (6/12, 6/12 vs. 10/11; and 1/12, 1/12 vs. 5/11; all p < 0.05), as well as the IVA + MET group (1/11 vs. 10/11, p < 0.01; and 1/11 vs. 5/11, p < 0.05). The induction rate of VT/VF was lower in the IVA + MET group, compared to the MET group (1/11 vs. 6/12, p < 0.05). H&E and Masson's staining revealed that compared with the MI group, the left ventricular infarction area was lower in the IVA, MET, and IVA + MET groups (p < 0.05, p < 0.05, and p < 0.01, respectively), while collagen volume fraction (CVF) also was lower in the other groups (all p < 0.01). The left ventricular infarction area and CVF both were lower in the IVA + MET group, compared to the MET group (p < 0.05 and p < 0.01, respectively). The immunohistochemistry and Western blot revealed that p-Cx43 expression was higher in the treatment groups, compared with the MI group (all p < 0.01). Conclusions IVA can reduce the incidence of ventricular arrhythmia after MI in male rats by improving both structural and electrical remodeling, and the combination of IVA and MET is even more effective.
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Affiliation(s)
- Li-ping Jiang
- Department of General Medicine, Mengchao Hepatobiliary Hospital of Fujian Medical University, Fuzhou, China
| | - Jing-jing Lin
- Department of Cardiology, Fujian Medical University Union Hospital and Fujian Provincial Institute of Coronary Disease, Fuzhou, China
| | - Ting-pei Zhuang
- Department of Cardiology, Fujian Medical University Union Hospital and Fujian Provincial Institute of Coronary Disease, Fuzhou, China
| | - Wei-wei Wang
- Department of Cardiology, Fujian Medical University Union Hospital and Fujian Provincial Institute of Coronary Disease, Fuzhou, China
| | - Hang-zhou Wu
- Medical Insurance Office, Fujian Medical University Union Hospital, Fuzhou, China
| | - Fei-long Zhang
- Department of Cardiology, Fujian Medical University Union Hospital and Fujian Provincial Institute of Coronary Disease, Fuzhou, China
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18
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Pouranbarani E, Berg LA, Oliveira RS, Dos Santos RW, Nygren A. Improved Accuracy of Cardiac Tissue-Level Simulations by Considering Membrane Resistance as a Cellular-Level Optimization Objective. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2487-2490. [PMID: 33018511 DOI: 10.1109/embc44109.2020.9176128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cardiac cellular models are utilized as the building blocks for tissue simulation. One of the imprecisions of conventional cellular modeling, especially when the models are used in tissue-level modeling, stems from the mere consideration of cellular properties (e.g., action potential shape) in parameter tuning of the model. In our previous work, we put forward an accurate framework in which membrane resistance (Rm) reflecting inter-cellular characteristics, i.e., electrotonic effects, was considered alongside cellular features in cellular model fitting. This paper, for the first time, examines the hypothesis that considering Rm as an additional optimization objective improves the accuracy of tissue-level modeling. To study this hypothesis, after cellular-level optimization of a well-known model, source-sink mismatch configurations in a 2-dimensional model are investigated. The results demonstrate that including Rm in the optimization protocol yields a substantial improvement in the relative error of the critical transition border which is defined as the minimum window size between source and sink that wave propagates. Model developers can utilize the proposed concept during parameter tuning to increase the accuracy of models.
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19
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Oliver-Gelabert A, García-Mendívil L, Vallejo-Gil JM, Fresneda-Roldán PC, Andelová K, Fañanás-Mastral J, Vázquez-Sancho M, Matamala-Adell M, Sorribas-Berjón F, Ballester-Cuenca C, Tribulova N, Ordovás L, Raúl Diez E, Pueyo E. Automatic Quantification of Cardiomyocyte Dimensions and Connexin 43 Lateralization in Fluorescence Images. Biomolecules 2020; 10:E1334. [PMID: 32957719 PMCID: PMC7565961 DOI: 10.3390/biom10091334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/12/2020] [Accepted: 09/15/2020] [Indexed: 02/06/2023] Open
Abstract
Cardiomyocytes' geometry and connexin 43 (CX43) amount and distribution are structural features that play a pivotal role in electrical conduction. Their quantitative assessment is of high interest in the study of arrhythmias, but it is usually hampered by the lack of automatic tools. In this work, we propose a software algorithm (Myocyte Automatic Retrieval and Tissue Analyzer, MARTA) to automatically detect myocytes from fluorescent microscopy images of cardiac tissue, measure their morphological features and evaluate the expression of CX43 and its degree of lateralization. The proposed software is based on the generation of cell masks, contouring of individual cells, enclosing of cells in minimum area rectangles and splitting of these rectangles into end-to-end and middle compartments to estimate CX43 lateral-to-total ratio. Application to human ventricular tissue images shows that mean differences between automatic and manual methods in terms of cardiomyocyte length and width are below 4 μm. The percentage of lateral CX43 also agrees between automatic and manual evaluation, with the interquartile range approximately covering from 3% to 30% in both cases. MARTA is not limited by fiber orientation and has an optimized speed by using contour filtering, which makes it run hundreds of times faster than a trained expert. Developed for CX43 studies in the left ventricle, MARTA is a flexible tool applicable to morphometric and lateralization studies of other markers in any heart chamber or even skeletal muscle. This open-access software is available online.
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Affiliation(s)
- Antoni Oliver-Gelabert
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), Institute of Engineering Research (I3A), University of Zaragoza & Instituto de Investigación Sanitaria (IIS), 50018 Zaragoza, Spain; (A.O.-G.); (L.G.-M.); (L.O.)
| | - Laura García-Mendívil
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), Institute of Engineering Research (I3A), University of Zaragoza & Instituto de Investigación Sanitaria (IIS), 50018 Zaragoza, Spain; (A.O.-G.); (L.G.-M.); (L.O.)
| | - José María Vallejo-Gil
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Pedro Carlos Fresneda-Roldán
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Katarína Andelová
- Centre of Experimental Medicine, SAS, 84104 Bratislava, Slovakia; (K.A.); (N.T.)
| | - Javier Fañanás-Mastral
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Manuel Vázquez-Sancho
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Marta Matamala-Adell
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Fernando Sorribas-Berjón
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Carlos Ballester-Cuenca
- Department of Cardiovascular Surgery, University Hospital Miguel Servet, 50018 Zaragoza, Spain; (J.M.V.-G.); (P.C.F.-R.); (J.F.-M.); (M.V.-S.); (M.M.-A.); (F.S.-B.); (C.B.-C.)
| | - Narcisa Tribulova
- Centre of Experimental Medicine, SAS, 84104 Bratislava, Slovakia; (K.A.); (N.T.)
| | - Laura Ordovás
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), Institute of Engineering Research (I3A), University of Zaragoza & Instituto de Investigación Sanitaria (IIS), 50018 Zaragoza, Spain; (A.O.-G.); (L.G.-M.); (L.O.)
- Aragon Agency for Research and Development (ARAID), 50018 Zaragoza, Spain
| | - Emiliano Raúl Diez
- Institute of Experimental Medicine and Biology of Cuyo (IMBECU), CONICET, 855 5500 Mendoza, Argentina
| | - Esther Pueyo
- Biomedical Signal Interpretation and Computational Simulation (BSICoS), Institute of Engineering Research (I3A), University of Zaragoza & Instituto de Investigación Sanitaria (IIS), 50018 Zaragoza, Spain; (A.O.-G.); (L.G.-M.); (L.O.)
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 50018 Zaragoza, Spain
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20
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He Z. The control mechanisms of heart rate dynamics in a new heart rate nonlinear time series model. Sci Rep 2020; 10:4814. [PMID: 32179768 PMCID: PMC7075874 DOI: 10.1038/s41598-020-61562-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/21/2020] [Indexed: 12/19/2022] Open
Abstract
The control mechanisms and implications of heart rate variability (HRV) under the sympathetic (SNS) and parasympathetic nervous system (PNS) modulation remain poorly understood. Here, we establish the HR model/HRV responder using a nonlinear process derived from Newton's second law in stochastic self-restoring systems through dynamic analysis of physiological properties. We conduct model validation by testing, predictions, simulations, and sensitivity and time-scale analysis. We confirm that the outputs of the HRV responder can be accepted as the real data-generating process. Empirical studies show that the dynamic control mechanism of heart rate is a stable fixed point, rather than a strange attractor or transitions between a fixed point and a limit cycle; HR slope (amplitude) may depend on the ratio of cardiac disturbance or metabolic demand mean (standard deviation) to myocardial electrical resistance (PNS-SNS activity). For example, when metabolic demands remain unchanged, HR amplitude depends on PNS to SNS activity; when autonomic activity remains unchanged, HR amplitude during resting reflects basal metabolism. HR parameter alterations suggest that age-related decreased HRV, ultrareduced HRV in heart failure, and ultraelevated HRV in ST segment alterations refer to age-related decreased basal metabolism, impaired myocardial metabolism, and SNS hyperactivity triggered by myocardial ischemia, respectively.
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Affiliation(s)
- Zonglu He
- Faculty of Management and Economics, Kaetsu University, 2-8-4 Minami-cho, Hanakoganei, Kodaira-shi, Tokyo, 187-8578, Japan.
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21
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Yang X, Zhang L, Liu H, Shao Y, Zhang S. Cardiac Sympathetic Denervation Suppresses Atrial Fibrillation and Blood Pressure in a Chronic Intermittent Hypoxia Rat Model of Obstructive Sleep Apnea. J Am Heart Assoc 2020; 8:e010254. [PMID: 30757948 PMCID: PMC6405657 DOI: 10.1161/jaha.118.010254] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Background Chronic intermittent hypoxia ( CIH ) is a distinct pathological mechanism of obstructive sleep apnea ( OSA ), which is recognized as an independent risk factor for cardiovascular diseases. The aims of this study were to ascertain whether CIH induces atrial fibrillation ( AF ), to determine whether cardiac sympathetic denervation ( CSD ) can prevent it and suppress blood pressure, and to explore the potential molecular mechanisms involved. Methods and Results Sixty Sprague-Dawley male rats were randomly divided into 4 groups: sham, CSD , CIH , CIH + CSD . The rats were exposed either to CIH 8 hours daily or normoxia for 6 weeks. Cardiac pathology and structure were analyzed by hematoxylin and eosin staining and echocardiogram. ECG, blood pressure, body weight, and blood gas were recorded. Connexin 43 and tyrosine hydroxylase were detected by western blot, immunohistochemistry, and immunofluorescence. CIH induced atrial remodeling, and increased AF inducibility. CSD treatment reduced postapneic blood pressure rises and AF susceptibility, which could attenuate CIH -associated structural atrial arrhythmogenic remodeling. In addition, CIH -induced sympathetic nerve hyperinnervation and CSD treatment reduced sympathetic innervation, which may affect CIH -induced AF -associated sympathovagal imbalance. Connexin 43 was specifically downregulated in CIH , whereas CSD treatment increased its expression. Conclusions These results suggested CIH induces atrial remodeling, increases AF inducibility, results in sympathetic nerve hyperinnervation, and decreases connexin 43 expression, but CSD treatment reduces AF susceptibility, postapneic blood pressure increase, sympathetic innervation, and the alteration of Cx43, which may be a key point in the genesis of CIH -induced AF .
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Affiliation(s)
- Xuechao Yang
- 1 Department of Cardiothoracic Surgery The First Affiliated Hospital of Nanjing Medical University Nanjing Jiangsu People's Republic of China
| | - Linfei Zhang
- 1 Department of Cardiothoracic Surgery The First Affiliated Hospital of Nanjing Medical University Nanjing Jiangsu People's Republic of China
| | - Huan Liu
- 1 Department of Cardiothoracic Surgery The First Affiliated Hospital of Nanjing Medical University Nanjing Jiangsu People's Republic of China
| | - Yongfeng Shao
- 1 Department of Cardiothoracic Surgery The First Affiliated Hospital of Nanjing Medical University Nanjing Jiangsu People's Republic of China
| | - Shijiang Zhang
- 1 Department of Cardiothoracic Surgery The First Affiliated Hospital of Nanjing Medical University Nanjing Jiangsu People's Republic of China
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Wu SJ, Lin ZH, Lin YZ, Rao ZH, Lin JF, Wu LP, Li L. Dexmedetomidine Exerted Anti-arrhythmic Effects in Rat With Ischemic Cardiomyopathy via Upregulation of Connexin 43 and Reduction of Fibrosis and Inflammation. Front Physiol 2020; 11:33. [PMID: 32116751 PMCID: PMC7020758 DOI: 10.3389/fphys.2020.00033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/15/2020] [Indexed: 12/20/2022] Open
Abstract
Background Persistent myocardial ischemia post-myocardial infarction can lead to fatal ventricular arrhythmias such as ventricular tachycardia and fibrillation, both of which carry high mortality rates. Dexmedetomidine (Dex) is a highly selective α2-agonist used in surgery for congenital cardiac disease because of its antiarrhythmic properties. Dex has previously been reported to prevent or terminate various arrhythmias. The purpose of the present study was to determine the anti-arrhythmic properties of Dex in the context of ischemic cardiomyopathy (ICM) after myocardial infarction. Methods and Results We randomly allocated 48 rats with ICM, created by persistent ligation of the left anterior descending artery for 4 weeks, into six groups: Sham (n = 8), Sham + BML (n = 8), ICM (n = 8), ICM + BML (n = 8), ICM + Dex (n = 8), and ICM + Dex + BML (n = 8). Treatments started after ICM was confirmed (the day after echocardiographic measurement) and continued for 4 weeks (inject intraperitoneally, daily). Dex inhibited the generation of collagens, cytokines, and other inflammatory mediators in rats with ICM via the suppression of NF-κB activation and increased the distribution of connexin 43 (Cx43) via phosphorylation of adenosine 5′-monophosphate-activated protein kinase (AMPK). Dex reduced the occurrence of spontaneous ventricular arrhythmias (ventricular premature beat or ventricular tachycardia), decreased the inducibility quotient of ventricular arrhythmias induced by PES, and partly improved cardiac contraction. The AMPK antagonist BML-275 dihydrochloride (BML) partly weakened the cardioprotective effect of Dex. Conclusion Dex conferred anti-arrhythmic effects in the context of ICM via upregulation of Cx43 and suppression of inflammation and fibrosis. The anti-arrhythmic and anti-inflammatory properties of Dex may be mediated by phosphorylation of AMPK and subsequent suppression of NF-κB activation.
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Affiliation(s)
- Shu-Jie Wu
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhong-Hao Lin
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yuan-Zheng Lin
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhi-Heng Rao
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jia-Feng Lin
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Lian-Pin Wu
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Lei Li
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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23
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Prado NJ, Egan Beňová T, Diez ER, Knezl V, Lipták B, Ponce Zumino AZ, Llamedo-Soria M, Szeiffová Bačová B, Miatello RM, Tribulová N. Melatonin receptor activation protects against low potassium-induced ventricular fibrillation by preserving action potentials and connexin-43 topology in isolated rat hearts. J Pineal Res 2019; 67:e12605. [PMID: 31408542 DOI: 10.1111/jpi.12605] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 07/27/2019] [Accepted: 08/05/2019] [Indexed: 12/22/2022]
Abstract
Hypokalemia prolongs the QRS and QT intervals, deteriorates intercellular coupling, and increases the risk for arrhythmia. Melatonin preserves gap junctions and shortens action potential as potential antiarrhythmic mechanisms, but its properties under hypokalemia remain unknown. We hypothesized that melatonin protects against low potassium-induced arrhythmias through the activation of its receptors, resulting in action potential shortening and connexin-43 preservation. After stabilization in Krebs-Henseleit solution (4.5 mEq/L K+ ), isolated hearts from Wistar rats underwent perfusion with low-potassium (1 mEq/L) solution and melatonin (100 μmol/L), a melatonin receptor blocker (luzindole, 5 μmol/L), melatonin + luzindole or vehicle. The primary endpoint of the study was the prevention of ventricular fibrillation. Electrocardiography was used, and epicardial action potentials and heart function were measured and analyzed. The ventricular expression, dephosphorylation, and distribution of connexin-43 were examined. Melatonin reduced the incidence of low potassium-induced ventricular fibrillation from 100% to 59%, delayed the occurrence of ventricular fibrillation and induced a faster recovery of sinus rhythm during potassium restitution. Melatonin prevented QRS widening, action potential activation delay, and the prolongation of action potential duration at 50% of repolarization. Other ECG and action potential parameters, the left ventricular developed pressure, and nonsustained ventricular arrhythmias did not differ among groups. Melatonin prevented connexin-43 dephosphorylation and its abnormal topology (lateralization). Luzindole abrogated the protective effects of melatonin on electrophysiological properties and connexin-43 misdistribution. Our results indicate that melatonin receptor activation protects against low potassium-induced ventricular fibrillation, shortens action potential duration, preserves ventricular electrical activation, and prevents acute changes in connexin-43 distribution. All of these properties make melatonin a remarkable antifibrillatory agent.
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Affiliation(s)
- Natalia Jorgelina Prado
- Instituto de Medicina y Biología Experimental de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas, Mendoza, Argentina
| | - Tamara Egan Beňová
- Center of Experimental Medicine, Slovak Academy of Sciences, Institute for Heart Research, Bratislava, Slovakia
| | - Emiliano Raúl Diez
- Instituto de Medicina y Biología Experimental de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas, Mendoza, Argentina
- Instituto de Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Vladimír Knezl
- Center of Experimental Medicine, Slovak Academy of Sciences, Institute of Experimental Pharmacology and Toxicology, Bratislava, Slovakia
| | - Boris Lipták
- Center of Experimental Medicine, Slovak Academy of Sciences, Institute of Experimental Pharmacology and Toxicology, Bratislava, Slovakia
| | - Amira Zulma Ponce Zumino
- Instituto de Medicina y Biología Experimental de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas, Mendoza, Argentina
- Instituto de Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Mariano Llamedo-Soria
- Department of Electronic Engineering, Universidad Tecnológica Nacional, Buenos Aires, Argentina
| | - Barbara Szeiffová Bačová
- Center of Experimental Medicine, Slovak Academy of Sciences, Institute for Heart Research, Bratislava, Slovakia
| | - Roberto Miguel Miatello
- Instituto de Medicina y Biología Experimental de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas, Mendoza, Argentina
- Instituto de Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Narcisa Tribulová
- Center of Experimental Medicine, Slovak Academy of Sciences, Institute for Heart Research, Bratislava, Slovakia
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24
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Schaefer M, Gebhard MM, Gross W. The effect of melatonin on hearts in ischemia/reperfusion experiments without and with HTK cardioplegia. Bioelectrochemistry 2019; 129:170-178. [DOI: 10.1016/j.bioelechem.2019.05.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/29/2019] [Accepted: 05/30/2019] [Indexed: 11/16/2022]
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25
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A fundamental evaluation of the electrical properties and function of cardiac transverse tubules. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118502. [PMID: 31269418 DOI: 10.1016/j.bbamcr.2019.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/07/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
This work discusses active and passive electrical properties of transverse (T-)tubules in ventricular cardiomyocytes to understand the physiological roles of T-tubules. T-tubules are invaginations of the lateral membrane that provide a large surface for calcium-handling proteins to facilitate sarcomere shortening. Higher heart rates correlate with higher T-tubular densities in mammalian ventricular cardiomyocytes. We assess ion dynamics in T-tubules and the effects of sodium current in T-tubules on the extracellular potential, which leads to a partial reduction of the sodium current in deep segments of a T-tubule. We moreover reflect on the impact of T-tubules on macroscopic conduction velocity, integrating fundamental principles of action potential propagation and conduction. We also theoretically assess how the conduction velocity is affected by different T-tubular sodium current densities. Lastly, we critically assess literature on ion channel expression to determine whether action potentials can be initiated in T-tubules.
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26
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Jæger KH, Edwards AG, McCulloch A, Tveito A. Properties of cardiac conduction in a cell-based computational model. PLoS Comput Biol 2019; 15:e1007042. [PMID: 31150383 PMCID: PMC6561587 DOI: 10.1371/journal.pcbi.1007042] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 06/12/2019] [Accepted: 04/23/2019] [Indexed: 11/18/2022] Open
Abstract
The conduction of electrical signals through cardiac tissue is essential for maintaining the function of the heart, and conduction abnormalities are known to potentially lead to life-threatening arrhythmias. The properties of cardiac conduction have therefore been the topic of intense study for decades, but a number of questions related to the mechanisms of conduction still remain unresolved. In this paper, we demonstrate how the so-called EMI model may be used to study some of these open questions. In the EMI model, the extracellular space, the cell membrane, the intracellular space and the cell connections are all represented as separate parts of the computational domain, and the model therefore allows for study of local properties that are hard to represent in the classical homogenized bidomain or monodomain models commonly used to study cardiac conduction. We conclude that a non-uniform sodium channel distribution increases the conduction velocity and decreases the time delays over gap junctions of reduced coupling in the EMI model simulations. We also present a theoretical optimal cell length with respect to conduction velocity and consider the possibility of ephaptic coupling (i.e. cell-to-cell coupling through the extracellular potential) acting as an alternative or supporting mechanism to gap junction coupling. We conclude that for a non-uniform distribution of sodium channels and a sufficiently small intercellular distance, ephaptic coupling can influence the dynamics of the sodium channels and potentially provide cell-to-cell coupling when the gap junction connection is absent. The electrochemical wave traversing the heart during every beat is essential for cardiac pumping function and supply of blood to the body. Understanding the stability of this wave is crucial to understanding how lethal arrhythmias are generated. Despite this importance, our knowledge of the physical determinants of wave propagation are still evolving. One particular challenge has been the lack of accurate mathematical models of conduction at the cellular level. Because cardiac muscle is an electrical syncytium, in which direct charge transfer between cells drives wave propagation, classical bidomain and monodomain tissue models employ a homogenized approximation of this process. This approximation is not valid at the length scale of single cells, and prevents any analysis of how cellular structures impact cardiac conduction. Instead, so-called microdomain models must be used for these questions. Here we utilize a recently developed modelling framework that is well suited to represent small collections of cells. By applying this framework, we show that concentration of sodium channels at the longitudinal borders of myocytes accelerates cardiac conduction. We also demonstrate that when juxtaposed cells are sufficiently close, this non-uniform distribution induces large ephaptic currents, which contribute to intercellular coupling.
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Affiliation(s)
| | | | - Andrew McCulloch
- Department of Bioengineering, University of California, San Diego, California, United States of America
| | - Aslak Tveito
- Simula Research Laboratory, Oslo, Norway
- * E-mail:
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27
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Loppini A, Gizzi A, Ruiz-Baier R, Cherubini C, Fenton FH, Filippi S. Competing Mechanisms of Stress-Assisted Diffusivity and Stretch-Activated Currents in Cardiac Electromechanics. Front Physiol 2018; 9:1714. [PMID: 30559677 PMCID: PMC6287028 DOI: 10.3389/fphys.2018.01714] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 11/14/2018] [Indexed: 12/13/2022] Open
Abstract
We numerically investigate the role of mechanical stress in modifying the conductivity properties of cardiac tissue, and also assess the impact of these effects in the solutions generated by computational models for cardiac electromechanics. We follow the recent theoretical framework from Cherubini et al. (2017), proposed in the context of general reaction-diffusion-mechanics systems emerging from multiphysics continuum mechanics and finite elasticity. In the present study, the adapted models are compared against preliminary experimental data of pig right ventricle fluorescence optical mapping. These data contribute to the characterization of the observed inhomogeneity and anisotropy properties that result from mechanical deformation. Our novel approach simultaneously incorporates two mechanisms for mechano-electric feedback (MEF): stretch-activated currents (SAC) and stress-assisted diffusion (SAD); and we also identify their influence into the nonlinear spatiotemporal dynamics. It is found that (i) only specific combinations of the two MEF effects allow proper conduction velocity measurement; (ii) expected heterogeneities and anisotropies are obtained via the novel stress-assisted diffusion mechanisms; (iii) spiral wave meandering and drifting is highly mediated by the applied mechanical loading. We provide an analysis of the intrinsic structure of the nonlinear coupling mechanisms using computational tests conducted with finite element methods. In particular, we compare static and dynamic deformation regimes in the onset of cardiac arrhythmias and address other potential biomedical applications.
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Affiliation(s)
- Alessandro Loppini
- Unit of Nonlinear Physics and Mathematical Modeling, Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy
| | - Alessio Gizzi
- Unit of Nonlinear Physics and Mathematical Modeling, Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy
| | - Ricardo Ruiz-Baier
- Mathematical Institute, University of Oxford, Oxford, United Kingdom.,Laboratory of Mathematical Modelling, Institute of Personalized Medicine, Sechenov University, Moscow, Russia
| | - Christian Cherubini
- Unit of Nonlinear Physics and Mathematical Modeling, Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy.,ICRANet, Pescara, Italy
| | - Flavio H Fenton
- Georgia Institute of Technology, School of Physics, Atlanta, GA, United States
| | - Simonetta Filippi
- Unit of Nonlinear Physics and Mathematical Modeling, Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy.,ICRANet, Pescara, Italy
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Ectopic beats arise from micro-reentries near infarct regions in simulations of a patient-specific heart model. Sci Rep 2018; 8:16392. [PMID: 30401912 PMCID: PMC6219578 DOI: 10.1038/s41598-018-34304-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 10/12/2018] [Indexed: 02/05/2023] Open
Abstract
Ectopic beats are known to be involved in the initiation of a variety of cardiac arrhythmias. Although their location may vary, ectopic excitations have been found to originate from infarct areas, regions of micro-fibrosis and other heterogeneous tissues. However, the underlying mechanisms that link ectopic foci to heterogeneous tissues have yet to be fully understood. In this work, we investigate the mechanism of micro-reentry that leads to the generation of ectopic beats near infarct areas using a patient-specific heart model. The patient-specific geometrical model of the heart, including scar and peri-infarct zones, is obtained through magnetic resonance imaging (MRI). The infarct region is composed of ischemic myocytes and non-conducting cells (fibrosis, for instance). Electrophysiology is captured using an established cardiac myocyte model of the human ventricle modified to describe ischemia. The simulation results clearly reveal that ectopic beats emerge from micro-reentries that are sustained by the heterogeneous structure of the infarct regions. Because microscopic information about the heterogeneous structure of the infarct regions is not available, Monte-Carlo simulations are used to identify the probabilities of an infarct region to behave as an ectopic focus for different levels of ischemia and different percentages of non-conducting cells. From the proposed model, it is observed that ectopic beats are generated when a percentage of non-conducting cells is near a topological metric known as the percolation threshold. Although the mechanism for micro-reentries was proposed half a century ago to be a source of ectopic beats or premature ventricular contractions during myocardial infarction, the present study is the first to reproduce this mechanism in-silico using patient-specific data.
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29
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Deng D, Nikolov P, Arevalo HJ, Trayanova NA. Optimal contrast-enhanced MRI image thresholding for accurate prediction of ventricular tachycardia using ex-vivo high resolution models. Comput Biol Med 2018; 102:426-432. [PMID: 30301573 PMCID: PMC6218273 DOI: 10.1016/j.compbiomed.2018.09.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 09/12/2018] [Accepted: 09/30/2018] [Indexed: 11/23/2022]
Abstract
Patient specific models created from contrast-enhanced (i.e. late-gadolinium, LGE) MRI images can be used for prediction of reentry location and clinical ablation planning. However, there is still a need for direct and systematic comparison between characteristics of ventricular tachycardia (VT) morphologies predicted in computational models and those acquired in clinical or experimental protocols. In this study, we aimed to: 1) assess the differences in VT morphologies predicted by modeling and recorded in experiments in terms of patterns and location of reentries, earliest and latest activation sites, and cycle lengths; and 2) define the optimal range of infarct tissue threshold values which provide best match between simulation and experimental results. To achieve these goals, we utilized LGE-MRI images from 4 swine hearts with inducible monomorphic VT. The images were segmented to identify non-infarcted myocardium, semi viable gray zone (GZ), and core scar based on pixel intensity. Several models were reconstructed from each LGE-MRI scan, with voxels of intensity between that of non-infarcted myocardium and 20-50% of the maximum intensity (in 10% increments) in the infarct region classified as GZ. VT induction was simulated in each model. Our simulation results showed that using GZ intensity thresholds of 20% or 30% resulted in the best match of simulated propagation patterns and reentry locations with those from the experiment. Overall, we matched 70% (7/10) morphologies for all the hearts. Our simulation shows that MRI-based computational models of hearts with myocardial infarction can accurately reproduce the majority of experimentally recorded post-infarction VTs.
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Affiliation(s)
- Dongdong Deng
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Plamen Nikolov
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Hermenegild J Arevalo
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA; Cardiac Modelling Department, Simula Research Laboratory, Fornebu, Norway
| | - Natalia A Trayanova
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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30
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Watanabe Y, Kishimoto T, Miki T, Seino S, Nakaya H, Matsumoto A. Ectopic overexpression of Kir6.1 in the mouse heart impacts on the life expectancy. Sci Rep 2018; 8:11723. [PMID: 30082733 PMCID: PMC6078942 DOI: 10.1038/s41598-018-30175-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 07/24/2018] [Indexed: 12/28/2022] Open
Abstract
We recently reported the reduced ATP-sensitive potassium (KATP) channel activities in the transgenic mouse heart overexpressing the vascular type KATP channel pore-forming subunit (Kir6.1). Although dysfunction of cardiac KATP channel has been nominated as a cause of cardiomyopathy in human, these transgenic mice looked normal as wild-type (WT) during the experiment period (~20 weeks). Extended observation period revealed unexpected deaths beginning from 30 weeks and about 50% of the transgenic mice died by 55 weeks. Surface ECG recordings from the transgenic mice at rest demonstrated the normal sinus rhythm and the regular ECG complex as well as the control WT mice except for prolonged QT interval. However, the stress ECG test with noradrenaline revealed abnormal intraventricular conduction delay and arrhythmogeneity in the transgenic mouse. Fibrotic changes in the heart tissue were remarkable in aged transgenic mice, and the cardiac fibrosis developed progressively at least from the age of 30 weeks. Gene expression analyses revealed the differentiation of cardiac fibroblasts to myofibroblasts with elevated cytokine expressions was initiated way in advance before the fibrotic changes and the upregulation of BNP in the ventricle. In sum, Kir6.1TG mice provide an electro-pathological disease concept originated from KATP channel dysfunction.
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Affiliation(s)
- Yasuhiro Watanabe
- Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takashi Kishimoto
- Department of Molecular Pathology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takashi Miki
- Department of Medical Physiology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Haruaki Nakaya
- Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Akio Matsumoto
- Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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31
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Zhang P, Xu J, Hu W, Yu D, Bai X. Effects of Pinocembrin Pretreatment on Connexin 43 (Cx43) Protein Expression After Rat Myocardial Ischemia-Reperfusion and Cardiac Arrhythmia. Med Sci Monit 2018; 24:5008-5014. [PMID: 30022020 PMCID: PMC6063136 DOI: 10.12659/msm.909162] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background Cardiac infarction frequently leads to arrhythmia and ischemia/reperfusion (I/R) aggravates cardiac injury. Pinocembrin can resist cerebral ischemia and decrease cardiac infarction area. This study thus generated a rat myocardial I/R model to assess the effect on ventricular rhythm and expression of gap junction connexin (Cx43). Material/Methods Male SD rats were randomly assigned into sham, model, and pinocembrin (30 mg/kg) pretreatment groups (N=15 each). The I/R model was generated by ligation of the left anterior descending coronary artery for 30 min. The pinocembrin group received intravenous injection 10 min before surgery. Heart rate (HR), mean artery pressure (MAP), rate pressure product (RPP), and arrhythmia were observed at 10 min before ischemia, 30 min after ischemia, and at 30, 60, and 120 min after reperfusion. ELISA was used to assess serum CK-MB and cTnI levels. Na+-K+ATPase and Ca+-Mg2+ATPase levels were quantified by spectrometry, followed by HE staining, IHC approach for Cx43 expression, and Western blot for Kir2.1 protein expression. Results Model rats had significantly lower HR, MAP, and RPP than in the sham group, and the pinocembrin pretreatment group had higher serum indexes. Arrhythmia index, CK-MB, and cTnI were higher in the model and pinocembrin groups, while Na+-K+ATPase, Ca+-Mg2+ATPase, Cx43, and Kir2.1 proteins were lower (p<0.05). Conclusions Pinocembrin alleviated ventricular arrhythmia in I/R rats via enhancing Na+-K+ATPase and Ca+-Mg2+ATPase activity and upregulating Cx43 and Kir2.1 protein expression.
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Affiliation(s)
- Peng Zhang
- Department of Cardiology, Minhang Hospital, Zhongshan Hospital, Fudan University, Shanghai, China (mainland)
| | - Jin Xu
- Department of Anesthesiology, Shanghai East Hospital, Tongji University, Shanghai, China (mainland)
| | - Wei Hu
- Department of Cardiology, Minhang Hospital, Zhongshan Hospital, Fudan University, Shanghai, China (mainland)
| | - Dong Yu
- Department of Cardiology, Minhang Hospital, Zhongshan Hospital, Fudan University, Shanghai, China (mainland)
| | - Xiaolu Bai
- Department of Cardiology, Minhang Hospital, Zhongshan Hospital, Fudan University, Shanghai, China (mainland)
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32
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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Naumenko N, Huusko J, Tuomainen T, Koivumäki JT, Merentie M, Gurzeler E, Alitalo K, Kivelä R, Ylä-Herttuala S, Tavi P. Vascular Endothelial Growth Factor-B Induces a Distinct Electrophysiological Phenotype in Mouse Heart. Front Physiol 2017; 8:373. [PMID: 28620319 PMCID: PMC5450225 DOI: 10.3389/fphys.2017.00373] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 05/18/2017] [Indexed: 12/22/2022] Open
Abstract
Vascular endothelial growth factor B (VEGF-B) is a potent mediator of vascular, metabolic, growth, and stress responses in the heart, but the effects on cardiac muscle and cardiomyocyte function are not known. The purpose of this study was to assess the effects of VEGF-B on the energy metabolism, contractile, and electrophysiological properties of mouse cardiac muscle and cardiac muscle cells. In vivo and ex vivo analysis of cardiac-specific VEGF-B TG mice indicated that the contractile function of the TG hearts was normal. Neither the oxidative metabolism of isolated TG cardiomyocytes nor their energy substrate preference showed any difference to WT cardiomyocytes. Similarly, myocyte Ca2+ signaling showed only minor changes compared to WT myocytes. However, VEGF-B overexpression induced a distinct electrophysiological phenotype characterized by ECG changes such as an increase in QRSp time and decreases in S and R amplitudes. At the level of isolated TG cardiomyocytes, these changes were accompanied with decreased action potential upstroke velocity and increased duration (APD60–70). These changes were partly caused by downregulation of sodium current (INa) due to reduced expression of Nav1.5. Furthermore, TG myocytes had alterations in voltage-gated K+ currents, namely decreased density of transient outward current (Ito) and total K+ current (Ipeak). At the level of transcription, these were accompanied by downregulation of Kv channel-interacting protein 2 (Kcnip2), a known modulatory subunit for Kv4.2/3 channel. Cardiac VEGF-B overexpression induces a distinct electrophysiological phenotype including remodeling of cardiomyocyte ion currents, which in turn induce changes in action potential waveform and ECG.
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Affiliation(s)
- Nikolay Naumenko
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Jenni Huusko
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Tomi Tuomainen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Jussi T Koivumäki
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Mari Merentie
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Erika Gurzeler
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - Kari Alitalo
- Wihuri Research Institute and Translational Cancer Biology Program, University of Helsinki, Biomedicum HelsinkiHelsinki, Finland
| | - Riikka Kivelä
- Wihuri Research Institute and Translational Cancer Biology Program, University of Helsinki, Biomedicum HelsinkiHelsinki, Finland
| | - Seppo Ylä-Herttuala
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland.,Heart Center and Gene Therapy Unit, Kuopio University HospitalKuopio, Finland
| | - Pasi Tavi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
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Abstract
Objective: Atrial fibrillation (AF) is the most common rapid cardiac arrhythmia associated with high morbidity and mortality. Stimulation of the sympathetic nerve is involved in AF occurrence. The gap junction protein connexin 43 (Cx43) plays a key role in electrical conduction velocity in cardiac tissues, and under expression of Cx43 was linked with AF. The aim of this study was to investigate whether Cx43 was involved in sympathetic AF. Methods: Fifteen dogs were randomly divided into 3 groups (5 in each group). Sympathetic AF was induced in dogs and isolated canine atrial myocytes by isoproterenol (ISO) perfusion and rapid atrium pacing (RAP). The expression levels of nerve growth factor (NGF) and tyrosine hydroxylase (TH) in the atrial tissues were detected using immunohistochemical staining. The transcription and protein expression of Cx43 in the AF cell model was measured. Subsequently, Cx43 was blocked by short interfering (si) RNA in atrial myocytes and the gap junctional inter-cellular communication was detected using the scrape-loading and dye transfer assay. Results: Sympathetic AF was successfully induced by a combination of ISO perfusion and RAP. The expression levels of NGF and TH were increased in the RAP group, and further increased in the RAP + ISO group. Tissue samples from the AF dogs had a lower Cx43 level than those of the control group (p<0.05). The expressions of mRNA and protein of Cx43 in sympathetic AF cell model decreased by 26% and 28%, respectively, when compared with the control group, with p<0.05. Silencing Cx43 in cells by siRNA could also efficiently reduce Cx43 expression. The relative levels of Cx45 mRNA were decreased by 73% compared with unaffected cells. The scrape-loading and dye transfer assay showed that gap junctional intercellular communication was hampered in the sympathetic AF cell model and silencing Cx43 could impede channel conduction. Conclusion: The results suggested that low expression of Cx43 was involved in sympathetic AF by influencing intercellular channel conduction. Intervention of Cx43 expression might be an appealing therapy to sympathetic AF.
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Quantitative assessment of passive electrical properties of the cardiac T-tubular system by FRAP microscopy. Proc Natl Acad Sci U S A 2017; 114:5737-5742. [PMID: 28507142 DOI: 10.1073/pnas.1702188114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Well-coordinated activation of all cardiomyocytes must occur on every heartbeat. At the cell level, a complex network of sarcolemmal invaginations, called the transverse-axial tubular system (TATS), propagates membrane potential changes to the cell core, ensuring synchronous and uniform excitation-contraction coupling. Although myocardial conduction of excitation has been widely described, the electrical properties of the TATS remain mostly unknown. Here, we exploit the formal analogy between diffusion and electrical conductivity to link the latter with the diffusional properties of TATS. Fluorescence recovery after photobleaching (FRAP) microscopy is used to probe the diffusion properties of TATS in isolated rat cardiomyocytes: A fluorescent dextran inside TATS lumen is photobleached, and signal recovery by diffusion of unbleached dextran from the extracellular space is monitored. We designed a mathematical model to correlate the time constant of fluorescence recovery with the apparent diffusion coefficient of the fluorescent molecules. Then, apparent diffusion is linked to electrical conductivity and used to evaluate the efficiency of the passive spread of membrane depolarization along TATS. The method is first validated in cells where most TATS elements are acutely detached by osmotic shock and then applied to probe TATS electrical conductivity in failing heart cells. We find that acute and pathological tubular remodeling significantly affect TATS electrical conductivity. This may explain the occurrence of defects in action potential propagation at the level of single T-tubules, recently observed in diseased cardiomyocytes.
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Steger A, Sinnecker D, Berkefeld A, Müller A, Gebhardt J, Dommasch M, Huster KM, Barthel P, Schmidt G. [Fragmented QRS. Relevance in clinical practice]. Herzschrittmacherther Elektrophysiol 2016; 26:235-41. [PMID: 26249048 DOI: 10.1007/s00399-015-0390-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The QRS complex represents the electrical depolarization of ventricular myocardium. In the case of an undisturbed depolarization, the QRS complex has a normal configuration and duration, but abnormal electrical conduction leads to widening of the QRS complex. The block of one of the Tawara branches results in a typical bundle branch block pattern. A QRS complex that cannot be classified as bundle branch block due to an atypical configuration and contains notched R or S waves is called a fragmented QRS. The underlying pathophysiologies are manifold and include myocardial scars induced by ischemic heart disease, myocardial fibrosis due to other diseases, primary cardiac pathologies as well as systemic diseases with cardiac involvement. Pathologies on the cellular level, such as ion channel dysfunctions, also correlate with fragmented QRS. Besides the diagnostic relevance, fragmented QRS is known to have prognostic properties, for example in identifying high risk patients with coronary artery disease, cardiomyopathy, Brugada syndrome and acquired long QT syndrome; however, fragmented QRS may also be detected in ECGs of healthy individuals.
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Affiliation(s)
- Alexander Steger
- I. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, München, Deutschland,
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Varghese A. Reciprocal Modulation of I K1-I Na Extends Excitability in Cardiac Ventricular Cells. Front Physiol 2016; 7:542. [PMID: 27895596 PMCID: PMC5108932 DOI: 10.3389/fphys.2016.00542] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/28/2016] [Indexed: 12/26/2022] Open
Abstract
The inwardly rectifying potassium current (IK1) and the fast inward sodium current (INa) are reciprocally modulated in mammalian ventricular myocytes. An increase in the expression of channels responsible for one of these two currents results in a corresponding increase in expression of the other. These currents are critical in the propagation of action potentials (AP) during the normal functioning of the heart. This study identifies a physiological role for IK1–INa reciprocal modulation in ventricular fiber activation thresholds and conduction. Simulations of action potentials in single cells and propagating APs in cardiac fibers were carried out using an existing model of electrical activity in cardiac ventricular myocytes. The conductances, GK1, of the inwardly rectifying potassium current, and GNa, of the fast inward sodium current were modified independently and in tandem to simulate reciprocal modulation. In single cells, independent modulation of GK1 alone resulted in changes in activation thresholds that were qualitatively similar to those for reciprocal GK1–GNa modulation and unlike those due to independent modulation of GNa alone, indicating that GK1 determines the cellular activation threshold. On the other hand, the variations in conduction velocity in cardiac cell fibers were similar for independent GNa modulation and for tandem changes in GK1–GNa, suggesting that GNa is primarily responsible for setting tissue AP conduction velocity. Conduction velocity dependence on GK1–GNa is significantly affected by the intercellular gap junction conductance. While the effects on the passive fiber space constant due to changes in both GK1 and the intercellular gap junction conductance, Ggj, were in line with linear cable theory predictions, both conductances had surprisingly large effects on fiber activation thresholds. Independent modulation of GK1 rendered cardiac fibers inexcitable at higher levels of GK1 whereas tandem GK1–GNa changes allowed fibers to remain excitable at high GK1 values. Reciprocal modulation of the inwardly rectifying potassium current and the fast inward sodium current may have a functional role in allowing cardiac tissue to remain excitable when IK1 is upregulated.
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Affiliation(s)
- Anthony Varghese
- Department of Computer Science, University of Wisconsin-River Falls River Falls, WI, USA
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39
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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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40
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Veeraraghavan R, Lin J, Keener JP, Gourdie R, Poelzing S. Potassium channels in the Cx43 gap junction perinexus modulate ephaptic coupling: an experimental and modeling study. Pflugers Arch 2016; 468:1651-61. [PMID: 27510622 DOI: 10.1007/s00424-016-1861-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/27/2016] [Accepted: 07/25/2016] [Indexed: 12/01/2022]
Abstract
It was recently demonstrated that cardiac sodium channels (Nav1.5) localized at the perinexus, an intercalated disc (ID) nanodomain associated with gap junctions (GJ), may contribute to electrical coupling between cardiac myocytes via an ephaptic mechanism. Impairment of ephaptic coupling by acute interstitial edema (AIE)-induced swelling of the perinexus was associated with arrhythmogenic, anisotropic conduction slowing. Given that Kir2.1 has also recently been reported to localize at intercalated discs, we hypothesized that Kir2.1 channels may reside within the perinexus and that inhibiting them may mitigate arrhythmogenic conduction slowing observed during AIE. Using gated stimulated emission depletion (gSTED) and stochastic optical reconstruction microscopy (STORM) super-resolution microscopy, we indeed find that a significant proportion of Kir2.1 channels resides within the perinexus. Moreover, whereas Nav1.5 inhibition during AIE exacerbated arrhythmogenic conduction slowing, inhibiting Kir2.1 channels during AIE preferentially increased transverse conduction velocity-decreasing anisotropy and ameliorating arrhythmia risk compared to AIE alone. Comparison of our results with a nanodomain computer model identified enrichment of both Nav1.5 and Kir2.1 at intercalated discs as key factors underlying the experimental observations. We demonstrate that Kir2.1 channels are localized within the perinexus alongside Nav1.5 channels. Further, targeting Kir2.1 modulates intercellular coupling between cardiac myocytes, anisotropy of conduction, and arrhythmia propensity in a manner consistent with a role for ephaptic coupling in cardiac conduction. For over half a century, electrical excitation in the heart has been thought to occur exclusively via gap junction-mediated ionic current flow between cells. Further, excitation was thought to depend almost exclusively on sodium channels with potassium channels being involved mainly in returning the cell to rest. Here, we demonstrate that sodium and potassium channels co-reside within nanoscale domains at cell-to-cell contact sites. Experimental and computer modeling results suggest a role for these channels in electrical coupling between cardiac muscle cells via an ephaptic mechanism working in tandem with gap junctions. This new insight into the mechanism of cardiac electrical excitation could pave the way for novel therapies against cardiac rhythm disturbances.
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Affiliation(s)
- Rengasayee Veeraraghavan
- Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic University, 2 Riverside Circle, Roanoke, VA, 24016, USA.
| | - Joyce Lin
- Department of Mathematics, California Polytechnic State University, San Luis Obispo, CA, USA
| | - James P Keener
- Department of Mathematics, University of Utah, 155 South 1400 East, Salt Lake City, UT, 84112, USA
| | - Robert Gourdie
- Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic University, 2 Riverside Circle, Roanoke, VA, 24016, USA.
- School of Biomedical Engineering and Sciences, Virginia Polytechnic University, Blacksburg, VA, USA.
| | - Steven Poelzing
- Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic University, 2 Riverside Circle, Roanoke, VA, 24016, USA.
- School of Biomedical Engineering and Sciences, Virginia Polytechnic University, Blacksburg, VA, USA.
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41
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Kopljar I, Gallacher DJ, De Bondt A, Cougnaud L, Vlaminckx E, Van den Wyngaert I, Lu HR. Functional and Transcriptional Characterization of Histone Deacetylase Inhibitor-Mediated Cardiac Adverse Effects in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Stem Cells Transl Med 2016; 5:602-12. [PMID: 27034410 DOI: 10.5966/sctm.2015-0279] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/14/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Histone deacetylase (HDAC) inhibitors possess therapeutic potential to reverse aberrant epigenetic changes associated with cancers, neurological diseases, and immune disorders. Unfortunately, clinical studies with some HDAC inhibitors displayed delayed cardiac adverse effects, such as atrial fibrillation and ventricular tachycardia. However, the underlying molecular mechanism(s) of HDAC inhibitor-mediated cardiotoxicity remains poorly understood and is difficult to detect in the early stages of preclinical drug development because of a delayed onset of effects. In the present study, we show for the first time in human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) that HDAC inhibitors (dacinostat, panobinostat, vorinostat, entinostat, and tubastatin-a) induce delayed dose-related cardiac dysfunction at therapeutic concentrations associated with cardiac adverse effects in humans. HDAC inhibitor-mediated delayed effects on the beating properties of hiPS-CMs developed after 12 hours by decreasing the beat rate, shortening the field potential duration, and inducing arrhythmic behavior under form of sustained contractions and fibrillation-like patterns. Transcriptional changes that are common between the cardiotoxic HDAC inhibitors but different from noncardiotoxic treatments identified cardiac-specific genes and pathways related to structural and functional changes in cardiomyocytes. Combining the functional data with epigenetic changes in hiPS-CMs allowed us to identify molecular targets that might explain HDAC inhibitor-mediated cardiac adverse effects in humans. Therefore, hiPS-CMs represent a valuable translational model to assess HDAC inhibitor-mediated cardiotoxicity and support identification of better HDAC inhibitors with an improved benefit-risk profile. SIGNIFICANCE Histone deacetylase (HDAC) inhibitors are a promising class of drugs to treat certain cancers, autoimmune, and neurodegenerative diseases. However, treated patients can experience various cardiac adverse events such as hearth rhythm disorders. This study found that human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) can predict cardiac adverse events in patients caused by HDAC inhibitors. Furthermore, transcriptional changes at the level of gene expression supported the effects on the beating properties of hiPS-CMs and highlight targets that might cause these cardiac adverse effects. hiPS-CMs represent a valuable translational model to assess HDAC inhibitor-mediated cardiotoxicity and to support development of safer HDAC inhibitors.
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MESH Headings
- Action Potentials
- Arrhythmias, Cardiac/chemically induced
- Arrhythmias, Cardiac/enzymology
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/physiopathology
- Cells, Cultured
- Dose-Response Relationship, Drug
- Epigenesis, Genetic/drug effects
- Gene Expression Profiling/methods
- Gene Expression Regulation
- Genotype
- Heart Diseases/chemically induced
- Heart Diseases/enzymology
- Heart Diseases/genetics
- Heart Diseases/physiopathology
- Heart Rate/drug effects
- Histone Deacetylase Inhibitors/toxicity
- Humans
- Induced Pluripotent Stem Cells/drug effects
- Induced Pluripotent Stem Cells/enzymology
- Myocardial Contraction/drug effects
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/enzymology
- Oligonucleotide Array Sequence Analysis
- Phenotype
- Risk Assessment
- Time Factors
- Transcription, Genetic/drug effects
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Affiliation(s)
- Ivan Kopljar
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
| | - David J Gallacher
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
| | - An De Bondt
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
| | | | - Eddy Vlaminckx
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
| | - Ilse Van den Wyngaert
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
| | - Hua Rong Lu
- Discovery Sciences, Janssen Research and Development, Janssen Pharmaceutica, Beerse, Belgium
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42
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Schilling JM, Horikawa YT, Zemljic-Harpf AE, Vincent KP, Tyan L, Yu JK, McCulloch AD, Balijepalli RC, Patel HH, Roth DM. Electrophysiology and metabolism of caveolin-3-overexpressing mice. Basic Res Cardiol 2016; 111:28. [PMID: 27023865 DOI: 10.1007/s00395-016-0542-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/17/2016] [Indexed: 10/22/2022]
Abstract
Caveolin-3 (Cav-3) plays a critical role in organizing signaling molecules and ion channels involved in cardiac conduction and metabolism. Mutations in Cav-3 are implicated in cardiac conduction abnormalities and myopathies. Additionally, cardiac-specific overexpression of Cav-3 (Cav-3 OE) is protective against ischemic and hypertensive injury, suggesting a potential role for Cav-3 in basal cardiac electrophysiology and metabolism involved in stress adaptation. We hypothesized that overexpression of Cav-3 may alter baseline cardiac conduction and metabolism. We examined: (1) ECG telemetry recordings at baseline and during pharmacological interventions, (2) ion channels involved in cardiac conduction with immunoblotting and computational modeling, and (3) baseline metabolism in Cav-3 OE and transgene-negative littermate control mice. Cav-3 OE mice had decreased heart rates, prolonged PR intervals, and shortened QTc intervals with no difference in activity compared to control mice. Dobutamine or propranolol did not cause significant changes between experimental groups in maximal (dobutamine) or minimal (propranolol) heart rate. Cav-3 OE mice had an overall lower chronotropic response to atropine. The expression of Kv1.4 and Kv4.3 channels, Nav1.5 channels, and connexin 43 were increased in Cav-3 OE mice. A computational model integrating the immunoblotting results indicated shortened action potential duration in Cav-3 OE mice linking the change in channel expression to the observed electrophysiology phenotype. Metabolic profiling showed no gross differences in VO2, VCO2, respiratory exchange ratio, heat generation, and feeding or drinking. In conclusion, Cav-3 OE mice have changes in ECG intervals, heart rates, and cardiac ion channel expression. These findings give novel mechanistic insights into previously reported Cav-3 dependent cardioprotection.
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Affiliation(s)
- Jan M Schilling
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Yousuke T Horikawa
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.,Department of Pediatrics, Sharp Rees-Stealy Medical Group, San Diego, CA, USA
| | - Alice E Zemljic-Harpf
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Kevin P Vincent
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Leonid Tyan
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Judith K Yu
- Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.,Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Hemal H Patel
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - David M Roth
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA. .,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA.
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43
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The crossroads of inflammation, fibrosis, and arrhythmia following myocardial infarction. J Mol Cell Cardiol 2015; 91:114-22. [PMID: 26739214 DOI: 10.1016/j.yjmcc.2015.12.024] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/23/2015] [Accepted: 12/26/2015] [Indexed: 01/08/2023]
Abstract
Optimal healing of damaged tissue following myocardial infarction (MI) requires a coordinated cellular response that can be divided into three phases: inflammatory, proliferative/reparative, and maturation. The inflammatory phase, characterized by rapid influx of cytokines, chemokines, and immune cells, is critical to the removal of damaged tissue. The onset of the proliferative/reparative phase is marked by increased proliferation of myofibroblasts and secretion of collagen to replace dead tissue. Lastly, crosslinking of collagen fibers and apoptosis of immune cells marks the maturation phase. Excessive inflammation or fibrosis has been linked to increased incidence of arrhythmia and other MI-related pathologies. This review describes the roles of inflammation and fibrosis in arrhythmogenesis and prospective therapies for anti-arrhythmic treatment.
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44
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Tse G, Yeo JM. Conduction abnormalities and ventricular arrhythmogenesis: The roles of sodium channels and gap junctions. IJC HEART & VASCULATURE 2015; 9:75-82. [PMID: 26839915 PMCID: PMC4695916 DOI: 10.1016/j.ijcha.2015.10.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/19/2015] [Indexed: 01/12/2023]
Abstract
Ventricular arrhythmias arise from disruptions in the normal orderly sequence of electrical activation and recovery of the heart. They can be categorized into disorders affecting predominantly cellular depolarization or repolarization, or those involving action potential (AP) conduction. This article briefly discusses the factors causing conduction abnormalities in the form of unidirectional conduction block and reduced conduction velocity (CV). It then examines the roles that sodium channels and gap junctions play in AP conduction. Finally, it synthesizes experimental results to illustrate molecular mechanisms of how abnormalities in these proteins contribute to such conduction abnormalities and hence ventricular arrhythmogenesis, in acquired pathologies such as acute ischaemia and heart failure, as well as inherited arrhythmic syndromes.
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Affiliation(s)
- Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, SW7 2AZ, UK
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45
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Seidel T, Edelmann JC, Sachse FB. Analyzing Remodeling of Cardiac Tissue: A Comprehensive Approach Based on Confocal Microscopy and 3D Reconstructions. Ann Biomed Eng 2015; 44:1436-1448. [PMID: 26399990 DOI: 10.1007/s10439-015-1465-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/18/2015] [Indexed: 01/20/2023]
Abstract
Microstructural characterization of cardiac tissue and its remodeling in disease is a crucial step in many basic research projects. We present a comprehensive approach for three-dimensional characterization of cardiac tissue at the submicrometer scale. We developed a compression-free mounting method as well as labeling and imaging protocols that facilitate acquisition of three-dimensional image stacks with scanning confocal microscopy. We evaluated the approach with normal and infarcted ventricular tissue. We used the acquired image stacks for segmentation, quantitative analysis and visualization of important tissue components. In contrast to conventional mounting, compression-free mounting preserved cell shapes, capillary lumens and extracellular laminas. Furthermore, the new approach and imaging protocols resulted in high signal-to-noise ratios at depths up to 60 µm. This allowed extensive analyzes revealing major differences in volume fractions and distribution of cardiomyocytes, blood vessels, fibroblasts, myofibroblasts and extracellular space in control vs. infarct border zone. Our results show that the developed approach yields comprehensive data on microstructure of cardiac tissue and its remodeling in disease. In contrast to other approaches, it allows quantitative assessment of all major tissue components. Furthermore, we suggest that the approach will provide important data for physiological models of cardiac tissue at the submicrometer scale.
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Affiliation(s)
- T Seidel
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA
| | - J-C Edelmann
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Fritz-Haber-Weg 1, 76131 Karlsruhe, Germany
| | - F B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112
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46
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Meens MJ, Kwak BR, Duffy HS. Role of connexins and pannexins in cardiovascular physiology. Cell Mol Life Sci 2015; 72:2779-92. [PMID: 26091747 PMCID: PMC11113959 DOI: 10.1007/s00018-015-1959-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 12/26/2022]
Abstract
Connexins and pannexins form connexons, pannexons and membrane channels, which are critically involved in many aspects of cardiovascular physiology. For that reason, a vast number of studies have addressed the role of connexins and pannexins in the arterial and venous systems as well as in the heart. Moreover, a role for connexins in lymphatics has recently also been suggested. This review provides an overview of the current knowledge regarding the involvement of connexins and pannexins in cardiovascular physiology.
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Affiliation(s)
- Merlijn J. Meens
- Department of Pathology and Immunology, University of Geneva, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland
- Department of Medical Specializations-Cardiology, University of Geneva, Geneva, Switzerland
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland
- Department of Medical Specializations-Cardiology, University of Geneva, Geneva, Switzerland
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47
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Billman GE, Del Rio CL. Editorial: Cardiac electronic remodeling and susceptibility to arrhythmias: an introduction and brief historical overview. Front Physiol 2015. [PMID: 26217235 PMCID: PMC4491600 DOI: 10.3389/fphys.2015.00196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- George E Billman
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA
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48
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Schulz R, Görge PM, Görbe A, Ferdinandy P, Lampe PD, Leybaert L. Connexin 43 is an emerging therapeutic target in ischemia/reperfusion injury, cardioprotection and neuroprotection. Pharmacol Ther 2015; 153:90-106. [PMID: 26073311 DOI: 10.1016/j.pharmthera.2015.06.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/29/2015] [Indexed: 12/22/2022]
Abstract
Connexins are widely distributed proteins in the body that are crucially important for heart and brain functions. Six connexin subunits form a connexon or hemichannel in the plasma membrane. Interactions between two hemichannels in a head-to-head arrangement result in the formation of a gap junction channel. Gap junctions are necessary to coordinate cell function by passing electrical current flow between heart and nerve cells or by allowing exchange of chemical signals and energy substrates. Apart from its localization at the sarcolemma of cardiomyocytes and brain cells, connexins are also found in the mitochondria where they are involved in the regulation of mitochondrial matrix ion fluxes and respiration. Connexin expression is affected by age and gender as well as several pathophysiological alterations such as hypertension, hypertrophy, diabetes, hypercholesterolemia, ischemia, post-myocardial infarction remodeling or heart failure, and post-translationally connexins are modified by phosphorylation/de-phosphorylation and nitros(yl)ation which can modulate channel activity. Using knockout/knockin technology as well as pharmacological approaches, one of the connexins, namely connexin 43, has been identified to be important for cardiac and brain ischemia/reperfusion injuries as well as protection from it. Therefore, the current review will focus on the importance of connexin 43 for irreversible injury of heart and brain tissues following ischemia/reperfusion and will highlight the importance of connexin 43 as an emerging therapeutic target in cardio- and neuroprotection.
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Affiliation(s)
- Rainer Schulz
- Institut für Physiologie, JustusLiebig Universität Giessen, Gießen, Germany.
| | | | - Anikó Görbe
- Cardiovascular Research Group, Department of Biochemistry, Faculty of Medicine, University of Szeged, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Péter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Luc Leybaert
- Physiology Group, Department Basic Medical Sciences, Ghent University, Belgium
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