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Kappadan V, Sohi A, Parlitz U, Luther S, Uzelac I, Fenton F, Peters NS, Christoph J, Ng FS. Optical mapping of contracting hearts. J Physiol 2023; 601:1353-1370. [PMID: 36866700 PMCID: PMC10952556 DOI: 10.1113/jp283683] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Optical mapping is a widely used tool to record and visualize the electrophysiological properties in a variety of myocardial preparations such as Langendorff-perfused isolated hearts, coronary-perfused wedge preparations, and cell culture monolayers. Motion artifact originating from the mechanical contraction of the myocardium creates a significant challenge to performing optical mapping of contracting hearts. Hence, to minimize the motion artifact, cardiac optical mapping studies are mostly performed on non-contracting hearts, where the mechanical contraction is removed using pharmacological excitation-contraction uncouplers. However, such experimental preparations eliminate the possibility of electromechanical interaction, and effects such as mechano-electric feedback cannot be studied. Recent developments in computer vision algorithms and ratiometric techniques have opened the possibility of performing optical mapping studies on isolated contracting hearts. In this review, we discuss the existing techniques and challenges of optical mapping of contracting hearts.
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Affiliation(s)
- Vineesh Kappadan
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Anies Sohi
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Ulrich Parlitz
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Stefan Luther
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Ilija Uzelac
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Flavio Fenton
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Nicholas S Peters
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Jan Christoph
- Cardiovascular Research InstituteUniversity of CaliforniaSan FranciscoCAUSA
| | - Fu Siong Ng
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
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2
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Nayir S, Lacour SP, Kucera JP. Active force generation contributes to the complexity of spontaneous activity and to the response to stretch of murine cardiomyocyte cultures. J Physiol 2022; 600:3287-3312. [PMID: 35679256 PMCID: PMC9541716 DOI: 10.1113/jp283083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/01/2022] [Indexed: 11/17/2022] Open
Abstract
Abstract Cardiomyocyte cultures exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. In such preparations, beat rate variability exhibits features similar to those of heart rate variability in vivo. Mechanical deformations and forces feed back on the electrical properties of cardiomyocytes, but it is not fully elucidated how this mechano‐electrical interplay affects beating variability in such preparations. Using stretchable microelectrode arrays, we assessed the effects of the myosin inhibitor blebbistatin and the non‐selective stretch‐activated channel blocker streptomycin on beating variability and on the response of neonatal or fetal murine ventricular cell cultures against deformation. Spontaneous electrical activity was recorded without stretch and upon predefined deformation protocols (5% uniaxial and 2% equibiaxial strain, applied repeatedly for 1 min every 3 min). Without stretch, spontaneous activity originated from the edge of the preparations, and its site of origin switched frequently in a complex manner across the cultures. Blebbistatin did not change mean beat rate, but it decreased the spatial complexity of spontaneous activity. In contrast, streptomycin did not exert any manifest effects. During the deformation protocols, beat rate increased transiently upon stretch but, paradoxically, also upon release. Blebbistatin attenuated the response to stretch, whereas this response was not affected by streptomycin. Therefore, our data support the notion that in a spontaneously firing network of cardiomyocytes, active force generation, rather than stretch‐activated channels, is involved mechanistically in the complexity of the spatiotemporal patterns of spontaneous activity and in the stretch‐induced acceleration of beating.
![]() Key points Monolayer cultures of cardiac cells exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. Beating variability in these preparations recapitulates the power‐law behaviour of heart rate variability in vivo. However, the effects of mechano‐electrical feedback on beating variability are not yet fully understood. Using stretchable microelectrode arrays, we examined the effects of the contraction uncoupler blebbistatin and the non‐specific stretch‐activated channel blocker streptomycin on beating variability and on stretch‐induced changes of beat rate. Without stretch, blebbistatin decreased the spatial complexity of beating variability, whereas streptomycin had no effects. Both stretch and release increased beat rate transiently; blebbistatin attenuated the increase of beat rate upon stretch, whereas streptomycin had no effects. Active force generation contributes to the complexity of spatiotemporal patterns of beating variability and to the increase of beat rate upon mechanical deformation. Our study contributes to the understanding of how mechano‐electrical feedback influences heart rate variability.
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Affiliation(s)
- Seyma Nayir
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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3
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Aras K, Gams A, Faye R, Brennan J, Goldrick K, Li J, Zhong Y, Chiang CH, Smith EH, Poston MD, Chivers J, Hanna P, Mori S, Ajijola OA, Shivkumar K, Hoover DB, Viventi J, Rogers JA, Bernus O, Efimov IR. Electrophysiology and Arrhythmogenesis in the Human Right Ventricular Outflow Tract. Circ Arrhythm Electrophysiol 2022; 15:e010630. [PMID: 35238622 PMCID: PMC9052172 DOI: 10.1161/circep.121.010630] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/17/2022] [Indexed: 12/12/2022]
Abstract
BACKGROUND Right ventricular outflow tract (RVOT) is a common source of ventricular tachycardia, which often requires ablation. However, the mechanisms underlying the RVOT's unique arrhythmia susceptibility remain poorly understood due to lack of detailed electrophysiological and molecular studies of the human RVOT. METHODS We conducted optical mapping studies in 16 nondiseased donor human RVOT preparations subjected to pharmacologically induced adrenergic and cholinergic stimulation to evaluate susceptibility to arrhythmias and characterize arrhythmia dynamics. RESULTS We found that under control conditions, RVOT has shorter action potential duration at 80% repolarization relative to the right ventricular apical region. Treatment with isoproterenol (100 nM) shortened action potential duration at 80% repolarization and increased incidence of premature ventricular contractions (P=0.003), whereas acetylcholine (100 μM) stimulation alone had no effect on action potential duration at 80% repolarization or premature ventricular contractions. However, acetylcholine treatment after isoproterenol stimulation reduced the incidence of premature ventricular contractions (P=0.034) and partially reversed action potential duration at 80% repolarization shortening (P=0.029). Immunolabeling of RVOT (n=4) confirmed the presence of cholinergic marker VAChT (vesicular acetylcholine transporter) in the region. Rapid pacing revealed RVOT susceptibility to both concordant and discordant alternans. Investigation into transmural arrhythmia dynamics showed that arrhythmia wave fronts and phase singularities (rotors) were relatively more organized in the endocardium than in the epicardium (P=0.006). Moreover, there was a weak but positive spatiotemporal autocorrelation between epicardial and endocardial arrhythmic wave fronts and rotors. Transcriptome analysis (n=10 hearts) suggests a trend that MAPK (mitogen-activated protein kinase) signaling, calcium signaling, and cGMP-PKG (protein kinase G) signaling are among the pathways that may be enriched in the male RVOT, whereas pathways of neurodegeneration may be enriched in the female RVOT. CONCLUSIONS Human RVOT electrophysiology is characterized by shorter action potential duration relative to the right ventricular apical region. Cholinergic right ventricular stimulation attenuates the arrhythmogenic effects of adrenergic stimulation, including increase in frequency of premature ventricular contractions and shortening of wavelength. Right ventricular arrhythmia is characterized by positive spatial-temporal autocorrelation between epicardial-endocardial arrhythmic wave fronts and rotors that are relatively more organized in the endocardium.
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Affiliation(s)
- Kedar Aras
- Department of Biomedical Engineering, the George Washington University, Washington, DC
- Department of Materials Science and Engineering, Ohio State University, Columbus, OH
| | - Anna Gams
- Department of Biomedical Engineering, the George Washington University, Washington, DC
| | - Rokhaya Faye
- Department of Biomedical Engineering, the George Washington University, Washington, DC
- LIRYC Institute, Bordeaux University, France
| | - Jaclyn Brennan
- Department of Biomedical Engineering, the George Washington University, Washington, DC
| | - Katherine Goldrick
- Department of Biomedical Engineering, the George Washington University, Washington, DC
| | - Jinghua Li
- Department of Biomedical Engineering, Northwestern University, Evanston, IL
- Department of Materials Science and Engineering, Ohio State University, Columbus, OH
| | - Yishan Zhong
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL
| | - Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Elizabeth H. Smith
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, TN
| | - Megan D. Poston
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, TN
| | - Jacqueline Chivers
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, TN
| | - Peter Hanna
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California Los Angeles, Los Angeles, CA
| | - Shumpei Mori
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California Los Angeles, Los Angeles, CA
| | - Olujimi A. Ajijola
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California Los Angeles, Los Angeles, CA
| | - Kalyanam Shivkumar
- UCLA Cardiac Arrhythmia Center and Neurocardiology Research Program of Excellence, University of California Los Angeles, Los Angeles, CA
| | - Donald B. Hoover
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, TN
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - John A. Rogers
- Department of Biomedical Engineering, Northwestern University, Evanston, IL
| | | | - Igor R. Efimov
- Department of Biomedical Engineering, the George Washington University, Washington, DC
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4
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Haissaguerre M, Cheniti G, Hocini M, Sacher F, Ramirez FD, Cochet H, Bear L, Tixier R, Duchateau J, Walton R, Surget E, Kamakura T, Marchand H, Derval N, Bordachar P, Ploux S, Takagi T, Pambrun T, Jais P, Labrousse L, Strik M, Ashikaga H, Calkins H, Vigmond E, Nademanee K, Bernus O, Dubois R. OUP accepted manuscript. Eur Heart J 2022; 43:1234-1247. [PMID: 35134898 PMCID: PMC8934691 DOI: 10.1093/eurheartj/ehab893] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 10/25/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Aims Mapping data of human ventricular fibrillation (VF) are limited. We performed detailed mapping of the activities underlying the onset of VF and targeted ablation in patients with structural cardiac abnormalities. Methods and results We evaluated 54 patients (50 ± 16 years) with VF in the setting of ischaemic (n = 15), hypertrophic (n = 8) or dilated cardiomyopathy (n = 12), or Brugada syndrome (n = 19). Ventricular fibrillation was mapped using body-surface mapping to identify driver (reentrant and focal) areas and invasive Purkinje mapping. Purkinje drivers were defined as Purkinje activities faster than the local ventricular rate. Structural substrate was delineated by electrogram criteria and by imaging. Catheter ablation was performed in 41 patients with recurrent VF. Sixty-one episodes of spontaneous (n = 10) or induced (n = 51) VF were mapped. Ventricular fibrillation was organized for the initial 5.0 ± 3.4 s, exhibiting large wavefronts with similar cycle lengths (CLs) across both ventricles (197 ± 23 vs. 196 ± 22 ms, P = 0.9). Most drivers (81%) originated from areas associated with the structural substrate. The Purkinje system was implicated as a trigger or driver in 43% of patients with cardiomyopathy. The transition to disorganized VF was associated with the acceleration of initial reentrant activities (CL shortening from 187 ± 17 to 175 ± 20 ms, P < 0.001), then spatial dissemination of drivers. Purkinje and substrate ablation resulted in the reduction of VF recurrences from a pre-procedural median of seven episodes [interquartile range (IQR) 4–16] to 0 episode (IQR 0–2) (P < 0.001) at 56 ± 30 months. Conclusions The onset of human VF is sustained by activities originating from Purkinje and structural substrate, before spreading throughout the ventricles to establish disorganized VF. Targeted ablation results in effective reduction of VF burden. Key question The initial phase of human ventricular fibrillation (VF) is critical as it involves the primary activities leading to sustained VF and arrhythmic sudden death. The origin of such activities is unknown. Key finding Body-surface mapping shows that most drivers (≈80%) during the initial VF phase originate from electrophysiologically defined structural substrates. Repetitive Purkinje activities can be elicited by programmed stimulation and are implicated as drivers in 37% of cardiomyopathy patients. Take-home message The onset of human VF is mostly associated with activities from the Purkinje network and structural substrate, before spreading throughout the ventricles to establish sustained VF. Targeted ablation reduces or eliminates VF recurrence.
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Affiliation(s)
| | - Ghassen Cheniti
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Meleze Hocini
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Frederic Sacher
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - F. Daniel Ramirez
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
| | - Hubert Cochet
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Laura Bear
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Romain Tixier
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Josselin Duchateau
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Rick Walton
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Elodie Surget
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Tsukasa Kamakura
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
| | - Hugo Marchand
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
| | - Nicolas Derval
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Pierre Bordachar
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Sylvain Ploux
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Takamitsu Takagi
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
| | - Thomas Pambrun
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Pierre Jais
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Louis Labrousse
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
| | - Mark Strik
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Hiroshi Ashikaga
- Arrhythmia Service, Johns Hopkins University School of Medicine, 600 N Wolfe St, Baltimore, MD 21287, USA
| | - Hugh Calkins
- Arrhythmia Service, Johns Hopkins University School of Medicine, 600 N Wolfe St, Baltimore, MD 21287, USA
| | - Ed Vigmond
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, IMB, U1045 Pessac, France
| | | | - Olivier Bernus
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
| | - Remi Dubois
- Department of Electrophysiology and Cardiac Stimulation, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- Institut Hospitalo-Universitaire Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France
- Univ Bordeaux, CRCTB, Inserm, U1045 Pessac, France
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The effective use of blebbistatin to study the action potential of cardiac pacemaker cells of zebrafish (Danio rerio) during incremental warming. Curr Res Physiol 2022; 5:48-54. [PMID: 35128467 PMCID: PMC8803472 DOI: 10.1016/j.crphys.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 01/12/2022] [Accepted: 01/12/2022] [Indexed: 12/11/2022] Open
Abstract
Blebbistatin potently inhibits actin-myosin interaction, preventing contractile activity of excitable cells including cardiac myocytes, despite electrical excitation of an action potential (AP). We collected intracellular microelectrode recordings of pacemaker cells located in the sinoatrial region (SAR) of the zebrafish heart at room temperature and during acute warming to investigate whether or not blebbistatin inhibition of contraction significantly alters pacemaker cell electrophysiology. Changes were evaluated based on 16 variables that characterized the AP waveform. None of these AP variables nor the spontaneous heart rate were significantly modified with the application of 10 μM blebbistatin when recordings were made at room temperature. Compared with the control group, the blebbistatin-treated group showed minor changes in the rate of spontaneous diastolic depolarization (P = 0.027) and the 50% and 80% repolarization (P = 0.008 and 0.010, respectively) in the 26°C–29°C temperature bin, but not at higher temperatures. These findings suggest that blebbistatin is an effective excitation-contraction uncoupler that does not appreciably affect APs generated in pacemaking cells of the SAR and can, therefore, be used in zebrafish cardiac studies. Blebbistatin uncouples excitation-contraction in zebrafish cardiomyocytes. Blebbistatin does not modify the pacemaker action potential variables. Temperature does not modify the effect of blebbistatin. First validation of the use of blebbistatin in adult fish. Methodology of intracellular microelectrode recording of zebrafish pacemaker cells.
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6
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Swift LM, Kay MW, Ripplinger CM, Posnack NG. Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research. Am J Physiol Heart Circ Physiol 2021; 321:H1005-H1013. [PMID: 34623183 DOI: 10.1152/ajpheart.00477.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Optical mapping is an imaging technique that is extensively used in cardiovascular research, wherein parameter-sensitive fluorescent indicators are used to study the electrophysiology and excitation-contraction coupling of cardiac tissues. Despite many benefits of optical mapping, eliminating motion artifacts within the optical signals is a major challenge, as myocardial contraction interferes with the faithful acquisition of action potentials and intracellular calcium transients. As such, excitation-contraction uncoupling agents are frequently used to reduce signal distortion by suppressing contraction. When compared with other uncoupling agents, blebbistatin is the most frequently used, as it offers increased potency with minimal direct effects on cardiac electrophysiology. Nevertheless, blebbistatin may exert secondary effects on electrical activity, metabolism, and coronary flow, and the incorrect administration of blebbistatin to cardiac tissue can prove detrimental, resulting in erroneous interpretation of optical mapping results. In this "Getting It Right" perspective, we briefly review the literature regarding the use of blebbistatin in cardiac optical mapping experiments, highlight potential secondary effects of blebbistatin on cardiac electrical activity and metabolic demand, and conclude with the consensus of the authors on best practices for effectively using blebbistatin in optical mapping studies of cardiac tissue.
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Affiliation(s)
- Luther M Swift
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
| | - Matthew W Kay
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | | | - Nikki Gillum Posnack
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia.,Department of Pediatrics, George Washington University, Washington, District of Columbia.,Department of Pharmacology and Physiology, George Washington University, Washington, District of Columbia
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7
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Landaw J, Yuan X, Chen PS, Qu Z. The transient outward potassium current plays a key role in spiral wave breakup in ventricular tissue. Am J Physiol Heart Circ Physiol 2021; 320:H826-H837. [PMID: 33385322 PMCID: PMC8082802 DOI: 10.1152/ajpheart.00608.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/22/2020] [Accepted: 12/22/2020] [Indexed: 11/22/2022]
Abstract
Spiral wave reentry as a mechanism of lethal ventricular arrhythmias has been widely demonstrated in animal experiments and recordings from human hearts. It has been shown that in structurally normal hearts spiral waves are unstable, breaking up into multiple wavelets via dynamical instabilities. However, many of the second-generation action potential models give rise only to stable spiral waves, raising issues regarding the underlying mechanisms of spiral wave breakup. In this study, we carried out computer simulations of two-dimensional homogeneous tissues using five ventricular action potential models. We show that the transient outward potassium current (Ito), although it is not required, plays a key role in promoting spiral wave breakup in all five models. As the maximum conductance of Ito increases, it first promotes spiral wave breakup and then stabilizes the spiral waves. In the absence of Ito, speeding up the L-type calcium kinetics can prevent spiral wave breakup, however, with the same speedup kinetics, spiral wave breakup can be promoted by increasing Ito. Increasing Ito promotes single-cell dynamical instabilities, including action potential duration alternans and chaos, and increasing Ito further suppresses these action potential dynamics. These cellular properties agree with the observation that increasing Ito first promotes spiral wave breakup and then stabilizes spiral waves in tissue. Implications of our observations to spiral wave dynamics in the real hearts and action potential model improvements are discussed.NEW & NOTEWORTHY Spiral wave breakup manifesting as multiple wavelets is a mechanism of ventricular fibrillation. It has been known that spiral wave breakup in cardiac tissue can be caused by a steeply sloped action potential duration restitution curve, a property mainly determined by the recovery of L-type calcium current. Here, we show that the transient outward potassium current (Ito) is another current that plays a key role in spiral wave breakup, that is, spiral waves can be stable for low and high maximum Ito conductance but breakup occurs for intermediate maximum Ito conductance. Since Ito is present in normal hearts of many species and required for Brugada syndrome, it may play an important role in the spiral wave stability and arrhythmogenesis under both normal condition and Brugada syndrome.
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Affiliation(s)
- Julian Landaw
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Xiaoping Yuan
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Information Engineering School, Hangzhou Dianzi University, Hangzhou, People's Republic of China
| | | | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
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8
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Bajelan S, Bahreini MS, Asgari Q, Mikaeili F. Viability and infectivity of Toxoplasma gondii tachyzoites exposed to Butanedione monoxime. J Parasit Dis 2020; 44:822-828. [PMID: 32837055 PMCID: PMC7430933 DOI: 10.1007/s12639-020-01259-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/05/2020] [Indexed: 12/17/2022] Open
Abstract
The most important pathogenesis factor in the Apicomplexa parasites is invasion to the host cell. Given the inhibitory role of Butanedione Monoxime (BDM) on myosin-actin interaction, this study aimed to investigate the effects of this molecule on the vitality and infectivity of Toxoplasma tachyzoites in order to provide a new option for vaccine development. The tachyzoites of the RH strain of Toxoplasma gondii were exposed to different concentrations (1, 2, 4, 8, 16, 32, 64, and 128 μg/mL) of BDM, and mortality effect was assessed by flow cytometry. Then, the penetration ability of the tachyzoites was investigated in HeLa and macrophage cell lines. The infectivity of exposed tachyzoites to BDM were also investigated in mice through following up and detecting the etiological factor. The highest percentage of mortality (72.69%) was seen in the tachyzoites exposed to 128 μg/mL of the compound. The tachyzoites exposed to 32, 64, and 128 μg/mL of BDM began the proliferation in HeLa cells after 48 h, while this proliferation was initiated within 24 h in macrophage cells. All the mice inoculated with the BDM-treated tachyzoites died after 13 days. The mean survival time of the mice receiving tachyzoites exposed to 128 μg/mL of BDM was 12.4 days, which was significantly different from the negative control group (p = 0.001). BDM, as the inhibitor of myosin-actin interaction, and other substances that block the entry of parasites into cells may be suitable candidates for vaccine production against Toxoplasma. Yet, future studies are required to be conducted on the issue.
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Affiliation(s)
- Sara Bajelan
- Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Saleh Bahreini
- Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Qasem Asgari
- Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Fattaneh Mikaeili
- Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
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9
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Pollnow S, Schwaderlapp G, Loewe A, Dössel O. Monitoring the dynamics of acute radiofrequency ablation lesion formation in thin-walled atria - a simultaneous optical and electrical mapping study. BIOMED ENG-BIOMED TE 2020; 65:327-341. [PMID: 31756159 DOI: 10.1515/bmt-2019-0013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 09/27/2019] [Indexed: 11/15/2022]
Abstract
Background Radiofrequency ablation (RFA) is a common approach to treat cardiac arrhythmias. During this intervention, numerous strategies are applied to indirectly estimate lesion formation. However, the assessment of the spatial extent of these acute injuries needs to be improved in order to create well-defined and durable ablation lesions. Methods We investigated the electrophysiological characteristics of rat atrial myocardium during an ex vivo RFA procedure with fluorescence-optical and electrical mapping. By analyzing optical data, the temporal growth of punctiform ablation lesions was reconstructed after stepwise RFA sequences. Unipolar electrograms (EGMs) were simultaneously recorded by a multielectrode array (MEA) before and after each RFA sequence. Based on the optical results, we searched for electrical features to delineate these lesions from healthy myocardium. Results Several unipolar EGM parameters were monotonically decreasing when distances between the electrode and lesion boundary were smaller than 2 mm. The negative component of the unipolar EGM [negative peak amplitude (Aneg)] vanished for distances lesser than 0.4 mm to the lesion boundary. Median peak-to-peak amplitude (Vpp) was decreased by 75% compared to baseline. Conclusion Aneg and Vpp are excellent parameters to discriminate the growing lesion area from healthy myocardium. The experimental setup opens new opportunities to investigate EGM characteristics of more complex ablation lesions.
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Affiliation(s)
- Stefan Pollnow
- Karlsruhe Institute of Technology, Institute of Biomedical Engineering, Fritz-Haber-Weg 1, Karlsruhe 76131, Germany, Tel.: +49-721-608-42650, Fax: +49-721-608-42789
| | - Gerald Schwaderlapp
- Karlsruhe Institute of Technology, Institute of Biomedical Engineering, Fritz-Haber-Weg 1, Karlsruhe 76131, Germany
| | - Axel Loewe
- Karlsruhe Institute of Technology, Institute of Biomedical Engineering, Fritz-Haber-Weg 1, Karlsruhe 76131, Germany
| | - Olaf Dössel
- Karlsruhe Institute of Technology, Institute of Biomedical Engineering, Fritz-Haber-Weg 1, Karlsruhe 76131, Germany
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10
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Kappadan V, Telele S, Uzelac I, Fenton F, Parlitz U, Luther S, Christoph J. High-Resolution Optical Measurement of Cardiac Restitution, Contraction, and Fibrillation Dynamics in Beating vs. Blebbistatin-Uncoupled Isolated Rabbit Hearts. Front Physiol 2020; 11:464. [PMID: 32528304 PMCID: PMC7264405 DOI: 10.3389/fphys.2020.00464] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 04/16/2020] [Indexed: 11/13/2022] Open
Abstract
Optical mapping is a high-resolution fluorescence imaging technique, that uses voltage- or calcium-sensitive dyes to visualize electrical excitation waves on the heart surface. However, optical mapping is very susceptible to the motion of cardiac tissue, which results in so-called motion artifacts in the fluorescence signal. To avoid motion artifacts, contractions of the heart muscle are typically suppressed using pharmacological excitation-contraction uncoupling agents, such as Blebbistatin. The use of pharmacological agents, however, may influence cardiac electrophysiology. Recently, it has been shown that numerical motion tracking can significantly reduce motion-related artifacts in optical mapping, enabling the simultaneous optical measurement of cardiac electrophysiology and mechanics. Here, we combine ratiometric optical mapping with numerical motion tracking to further enhance the robustness and accuracy of these measurements. We evaluate the method's performance by imaging and comparing cardiac restitution and ventricular fibrillation (VF) dynamics in contracting, non-working vs. Blebbistatin-arrested Langendorff-perfused rabbit hearts (N = 10). We found action potential durations (APD) to be, on average, 25 ± 5% shorter in contracting hearts compared to hearts uncoupled with Blebbistatin. The relative shortening of the APD was found to be larger at higher frequencies. VF was found to be significantly accelerated in contracting hearts, i.e., 9 ± 2Hz with Blebbistatin and 15 ± 4Hz without Blebbistatin, and maintained a broader frequency spectrum. In contracting hearts, the average number of phase singularities was NPS = 11 ± 4 compared to NPS = 6 ± 3 with Blebbistatin during VF on the anterior ventricular surface. VF inducibility was reduced with Blebbistatin. We found the effect of Blebbistatin to be concentration-dependent and reversible by washout. Aside from the electrophysiological characterization, we also measured and analyzed cardiac motion. Our findings may have implications for the interpretation of optical mapping data, and highlight that physiological conditions, such as oxygenation and metabolic demand, must be carefully considered in ex vivo imaging experiments.
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Affiliation(s)
- Vineesh Kappadan
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Saba Telele
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK e.V.), Partnersite Göttingen, Göttingen, Germany
| | - Ilija Uzelac
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Flavio Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Ulrich Parlitz
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK e.V.), Partnersite Göttingen, Göttingen, Germany.,Institute for the Dynamics of Complex Systems, University of Göttingen, Göttingen, Germany
| | - Stefan Luther
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK e.V.), Partnersite Göttingen, Göttingen, Germany.,Department of Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Christoph
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK e.V.), Partnersite Göttingen, Göttingen, Germany.,Department of Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany
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11
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Smirnov D, Pikunov A, Syunyaev R, Deviatiiarov R, Gusev O, Aras K, Gams A, Koppel A, Efimov IR. Genetic algorithm-based personalized models of human cardiac action potential. PLoS One 2020; 15:e0231695. [PMID: 32392258 PMCID: PMC7213718 DOI: 10.1371/journal.pone.0231695] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 03/31/2020] [Indexed: 11/21/2022] Open
Abstract
We present a novel modification of genetic algorithm (GA) which determines personalized parameters of cardiomyocyte electrophysiology model based on set of experimental human action potential (AP) recorded at different heart rates. In order to find the steady state solution, the optimized algorithm performs simultaneous search in the parametric and slow variables spaces. We demonstrate that several GA modifications are required for effective convergence. Firstly, we used Cauchy mutation along a random direction in the parametric space. Secondly, relatively large number of elite organisms (6-10% of the population passed on to new generation) was required for effective convergence. Test runs with synthetic AP as input data indicate that algorithm error is low for high amplitude ionic currents (1.6±1.6% for IKr, 3.2±3.5% for IK1, 3.9±3.5% for INa, 8.2±6.3% for ICaL). Experimental signal-to-noise ratio above 28 dB was required for high quality GA performance. GA was validated against optical mapping recordings of human ventricular AP and mRNA expression profile of donor hearts. In particular, GA output parameters were rescaled proportionally to mRNA levels ratio between patients. We have demonstrated that mRNA-based models predict the AP waveform dependence on heart rate with high precision. The latter also provides a novel technique of model personalization that makes it possible to map gene expression profile to cardiac function.
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Affiliation(s)
- Dmitrii Smirnov
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Andrey Pikunov
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Roman Syunyaev
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- The George Washington University, Washington, DC, United States of America
- Sechenov University, Moscow, Russia
| | | | | | - Kedar Aras
- The George Washington University, Washington, DC, United States of America
| | - Anna Gams
- The George Washington University, Washington, DC, United States of America
| | - Aaron Koppel
- The George Washington University, Washington, DC, United States of America
| | - Igor R. Efimov
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- The George Washington University, Washington, DC, United States of America
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12
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Scardigli M, Cannazzaro S, Coppini R, Crocini C, Yan P, Loew LM, Sartiani L, Cerbai E, Pavone FS, Sacconi L, Ferrantini C. Arrhythmia susceptibility in a rat model of acute atrial dilation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 154:21-29. [PMID: 32063273 DOI: 10.1016/j.pbiomolbio.2019.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 08/17/2019] [Accepted: 08/27/2019] [Indexed: 12/11/2022]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia, associated with an increased risk of stroke and heart failure. Acute AF occurs in response to sudden increases of atrial hemodynamic load, leading to atrial stretch. The mechanisms of stretch-induced AF were investigated in large mammals with controversial results. We optimized an approach to monitor rat atrial electrical activity using a red-shifted voltage sensitive dye (VSD). The methodology includes cauterization of the main ventricular coronary arteries, allowing improved atrial staining by the VSD and appropriate atrial perfusion for long experiments. Next, we developed a rat model of acute biatrial dilation (ABD) through the insertion of latex balloons into both atria, which could be inflated with controlled volumes. A chronic model of atrial dilation (spontaneous hypertensive rats; SHR) was used for comparison. ABD was performed on atria from healthy Wistar-Kyoto (WKY) rats (WKY-ABD). The atria were characterized in terms of arrhythmias susceptibility, action potential duration and conduction velocity. The occurrence of arrhythmias in WKY-ABD was significantly higher compared to non-dilated WKY atria. In WKY-ABD we found a reduction of conduction velocity, similar to that observed in SHR atria, while action potential duration was unchanged. Low-dose caffeine was used to introduce a drop of CV in WKY atria (WKY-caff), quantitatively similar to the one observed after ABD, but no increased arrhythmia susceptibility was observed with caffeine only. In conclusion, CV decrease is not sufficient to promote arrhythmias; enlargement of atrial surface is essential to create a substrate for acute reentry-based arrhythmias.
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Affiliation(s)
- M Scardigli
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino (FI), Italy
| | - S Cannazzaro
- National Institute of Optics, National Research Council, 50125, Florence, Italy
| | - R Coppini
- Division of Pharmacology, Department "NeuroFarBa,", University of Florence, 50139, Florence, Italy
| | - C Crocini
- Department of Molecular, Cellular, and Developmental Biology and BioFrontiers Institute, University of Colorado, Boulder, USA
| | - P Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - L M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - L Sartiani
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - E Cerbai
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino (FI), Italy; National Institute of Optics, National Research Council, 50125, Florence, Italy; Department of Physics and Astronomy, University of Florence, 50019, Sesto Fiorentino (FI), Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino (FI), Italy; National Institute of Optics, National Research Council, 50125, Florence, Italy
| | - C Ferrantini
- European Laboratory for Non-Linear Spectroscopy, 50019, Sesto Fiorentino (FI), Italy; Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, 50134, Florence, Italy.
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13
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Wang S, Rodríguez-Mañero M, Ibarra-Cortez SH, Kreidieh B, Valderrábano L, Hemam M, Tavares L, Blanco E, Valderrábano M. NS5806 Induces Electromechanically Discordant Alternans and Arrhythmogenic Voltage-Calcium Dynamics in the Isolated Intact Rabbit Heart. Front Physiol 2020; 10:1509. [PMID: 31920713 PMCID: PMC6933003 DOI: 10.3389/fphys.2019.01509] [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] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/29/2019] [Indexed: 12/19/2022] Open
Abstract
Background: NS5806 activates the transient outward potassium current I to, and has been claimed to reproduce Brugada Syndrome (BrS) in ventricular wedge preparations. I to modulates excitation-contraction coupling, which is critical in alternans dynamics. We explored NS5806-arrhythmogenic effects in the intact whole heart and its impact on alternans. Methods: Langendorff-perfused rabbit hearts (n = 20) underwent optical AP and Ca mapping during pacing at decremental cycle lengths (CL). Spontaneous arrhythmias and pacing-induced alternans was characterized at baseline (BL), after perfusing with NS5806, before and after adding verapamil (VP), and SEA0400 (SEA, n = 5 each), to modulate Ca-current and Na-Ca exchange, the main AP-Ca coupling mechanisms. Results: NS5806 induced BrS-like ECG features in 6 out of 20 hearts. NS5806 prolonged steady-state (3 Hz) action potential duration (APD) by 16.8%, Ca decay constant by 34%, and decreased conduction velocity (CV) by 52.6%. After NS5806 infusion, spontaneous ventricular ectopy (VE) and AP/Ca alternans occurred. Pacing-induced alternans during NS5806 infusion occurred at longer CL and were AP/Ca discordant from its onset. Spatially discordant alternans after NS5806 infusion had non-propagation-driven nodal line distribution. No spontaneous phase-2 reentry occurred. Under NS5806 + VP, alternans became AP/Ca concordant and only induced in two out of five; NS5806 + SEA did not affect alternans but suppressed spontaneous ectopy. Conclusions: NS5806 disrupts AP-Ca coupling and leads to Ca-driven, AP/Ca-discordant alternans and VE. Despite BrS-like ECG features, no spontaneous sustained arrhythmias or phase-2 reentry occurred. NS5806 does not fully reproduce BrS in the intact rabbit heart.
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Affiliation(s)
- Sufen Wang
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Moisés Rodríguez-Mañero
- Cardiology Department, Complejo Hospital Universitario de Santiago, Santiago de Compostela, Spain.,Instituto de Investigación Sanitaria (IDIS), Universidad de Santiago de Compostela, Santiago de Compostela, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV CB16/11/00226 - CB16/11/00420), Madrid, Spain
| | - Sergio H Ibarra-Cortez
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Bahij Kreidieh
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Laura Valderrábano
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Majd Hemam
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Liliana Tavares
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
| | - Elvin Blanco
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States.,Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX, United States
| | - Miguel Valderrábano
- Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston Methodist Research Institute, Houston, TX, United States
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14
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Swift LM, Jaimes R, McCullough D, Burke M, Reilly M, Maeda T, Zhang H, Ishibashi N, Rogers JM, Posnack NG. Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts. J Vis Exp 2019. [PMID: 31762469 DOI: 10.3791/60472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to larger animals. Yet, larger mammals are better suited for translational research questions related to normal cardiac physiology, pathophysiology, and preclinical testing of therapeutic agents. To overcome the technical barriers associated with employing a larger animal model in cardiac research, we describe an approach to measure physiological parameters in an isolated, Langendorff-perfused piglet heart. This approach combines two powerful experimental tools to evaluate the state of the heart: electrophysiology (EP) study and simultaneous optical mapping of transmembrane voltage and intracellular calcium using parameter sensitive dyes (RH237, Rhod2-AM). The described methodologies are well suited for translational studies investigating the cardiac conduction system, alterations in action potential morphology, calcium handling, excitation-contraction coupling and the incidence of cardiac alternans or arrhythmias.
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Affiliation(s)
- Luther M Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Rafael Jaimes
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Morgan Burke
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Marissa Reilly
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Takuya Maeda
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Center for Neuroscience Research, Children's National Hospital
| | - Hanyu Zhang
- Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham
| | - Nobuyuki Ishibashi
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Center for Neuroscience Research, Children's National Hospital
| | - Jack M Rogers
- Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences, George Washington University;
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15
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Nademanee K, Haissaguerre M, Hocini M, Nogami A, Cheniti G, Duchateau J, Behr ER, Saba M, Bokan R, Lou Q, Amnueypol M, Coronel R, Khongphatthanayothin A, Veerakul G. Mapping and Ablation of Ventricular Fibrillation Associated With Early Repolarization Syndrome. Circulation 2019; 140:1477-1490. [PMID: 31542949 DOI: 10.1161/circulationaha.118.039022] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We conducted a multicenter study to evaluate mapping and ablation of ventricular fibrillation (VF) substrates or VF triggers in early repolarization syndromes (ERS) or J-wave syndrome (JWS). METHODS We studied 52 patients with ERS (4 women; median age, 35 years) with recurrent VF episodes. Body surface electrocardiographic imaging and endocardial and epicardial electroanatomical mapping of both ventricles were performed during sinus rhythm and VF for localization of triggers, substrates, and drivers. Ablations were performed on VF substrates, defined as areas that had late depolarization abnormalities characterized by low-voltage fractionated late potentials, and VF triggers. RESULTS Fifty-one of the 52 patients had detailed mapping that revealed 2 phenotypes: group 1 had late depolarization abnormalities predominantly at the right ventricular (RV) epicardium (n=40), and group 2 had no depolarization abnormalities (n=11). Group 1 can be subcategorized into 2 groups: Group 1A included 33 patients with ERS with Brugada electrocardiographic pattern, and group 1B included 7 patients with ERS without Brugada electrocardiographic pattern. Late depolarization areas colocalize with VF driver areas. The anterior RV outflow tract/RV epicardium and the RV inferior epicardium are the major substrate sites for group 1. The Purkinje network is the leading underlying VF trigger in group 2 that had no substrates. Ablations were performed in 43 patients: 31 and 5 group 1 patients had only VF substrate ablation and VF substrates plus VF trigger, respectively (mean, 1.4±0.6 sessions); 6 group 2 patients and 1 patient without group classification had only Purkinje VF trigger ablation (mean, 1.2±0.4 sessions). Ablations were successful in reducing VF recurrences (P<0.0001). After follow-up of 31±26 months, 39 (91%) had no VF recurrences. CONCLUSIONS There are 2 phenotypes of ERS/J-wave syndrome: one with late depolarization abnormality as the underlying mechanism of high-amplitude J-wave elevation that predominantly resides in the RV outflow tract and RV inferolateral epicardium, serving as an excellent target for ablation, and the other with pure ERS devoid of VF substrates but with VF triggers that are associated with Purkinje sites. Ablation is effective in treating symptomatic patients with ERS/J-wave syndrome with frequent VF episodes.
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Affiliation(s)
- Koonlawee Nademanee
- Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand (K.N., A.K.).,Pacific Rim Electrophysiology Research Institute at Bumrungrad Hospital, Bangkok, Thailand, and Los Angeles, CA (K.N., M.A.)
| | - Michel Haissaguerre
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Pessac-Bordeaux, France (M.H., M.H., G.C, J.D.)
| | - Mélèze Hocini
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Pessac-Bordeaux, France (M.H., M.H., G.C, J.D.)
| | | | - Ghassen Cheniti
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Pessac-Bordeaux, France (M.H., M.H., G.C, J.D.)
| | - Josselin Duchateau
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Pessac-Bordeaux, France (M.H., M.H., G.C, J.D.)
| | - Elijah R Behr
- Cardiology Clinical Academic Group, Institute of Molecular and Clinical Sciences, St. George's, University of London, and St. George's University Hospitals NHS Foundation Trust London, UK (E.R.B., M.S.)
| | - Magdi Saba
- Cardiology Clinical Academic Group, Institute of Molecular and Clinical Sciences, St. George's, University of London, and St. George's University Hospitals NHS Foundation Trust London, UK (E.R.B., M.S.)
| | - Ryan Bokan
- CardioInsight Technologies, Medtronic, Minneapolis, MN (R.B., Q.L.)
| | - Qing Lou
- CardioInsight Technologies, Medtronic, Minneapolis, MN (R.B., Q.L.)
| | - Montawatt Amnueypol
- Pacific Rim Electrophysiology Research Institute at Bumrungrad Hospital, Bangkok, Thailand, and Los Angeles, CA (K.N., M.A.)
| | - Ruben Coronel
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands (R.C.)
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16
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Aras KK, Faye NR, Cathey B, Efimov IR. Critical Volume of Human Myocardium Necessary to Maintain Ventricular Fibrillation. Circ Arrhythm Electrophysiol 2019; 11:e006692. [PMID: 30376733 DOI: 10.1161/circep.118.006692] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Abnormal QT intervals, long QT or short QT, have been epidemiologically linked with sudden cardiac death because of ventricular fibrillation (VF). Consequently, Food and Drug Administration recommends testing all pharmacological agents for QT toxicity as a risk factor for cardiac toxicity. Such tests assess QT/QTc interval, which represents ventricular depolarization and repolarization. However, the current QT toxicity analysis does not account for the well-known anisotropy in cardiac tissue conductivity. Mines demonstrated in 1913 that cardiac wavelength (λ) determines inducibility of reentrant arrhythmia, where both repolarization time or action potential duration and conduction velocity determine λ=action potential duration×conduction velocity. We aimed to determine the role of anisotropic wavelength in inducibility of VF in explanted human left ventricular preparations. We tested the hypothesis that 3-dimensional cardiac wavelength, which takes into account anisotropic cardiac tissue conductivity, can accurately predict VF sustainability. METHODS We conducted panoramic optical mapping of coronary perfused human left ventricular wedge preparations subjected to pharmacologically induced shortening and prolongation of action potential duration, by IK,ATP agonist pinacidil and antagonist glybenclamide, respectively. This measured action potential duration, conduction velocity, and thus determined pacing cycle length-dependent wavelengths in longitudinal (λL), transverse (λTV), and transmural (λTM) directions using S1S1 pacing protocol, from which wavelength volume (Vλ) was determined, as Vλ=λL×λTV×λTM, and compared with tissue volume. We tested a hypothesis that tissue volume/Vλ ratio can predict VF sustainability. RESULTS At baseline, at pacing rate of 240 beats per minute, the wavelengths were λL=9.6±0.6 cm, λTV=4.2±0.3 cm, and λTM=5.8±0.2 cm, respectively (n=7), and thus Vλ=246.4±42.1 cm3. Administration of pinacidil at escalating concentrations progressively decreased Vλ, and VF became sustained, when tissue volume/Vλ was above safety factor κ=4.4±0.6 (n=9) during rapid pacing. Treatment with glybenclamide decreased VT/Vλ below κ at any pacing rate and prevented VF sustainability. CONCLUSIONS Sustained VF was only sustained in ventricular volume exceeding critical Vλ=λL×λTV×λTM.
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Affiliation(s)
- Kedar K Aras
- Department of Biomedical Engineering, George Washington University, Washington, DC
| | - Ndeye Rokhaya Faye
- Department of Biomedical Engineering, George Washington University, Washington, DC
| | - Brianna Cathey
- Department of Biomedical Engineering, George Washington University, Washington, DC
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC
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17
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Abstract
Optical mapping of electrical activity in the heart is based on voltage-sensitive and lipophilic fluorescence dyes. Optical signals recorded from cardiac cells correlate well with their transmembrane potentials. High spatiotemporal resolution, wide field mapping, and high sensitivity to transmembrane potential enable detailed characterization of action potential initiation and propagation. Optical mapping is used to study complex patterns of excitation propagation, including propagation across the sinoatrial and atrioventricular nodes and during atrial and ventricular arrhythmias.Optical mapping is used to study the role of reentrant activity in atrial and ventricular fibrillation.
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18
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An adaptive spatio-temporal Gaussian filter for processing cardiac optical mapping data. Comput Biol Med 2018; 102:267-277. [PMID: 29891242 DOI: 10.1016/j.compbiomed.2018.05.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/30/2018] [Accepted: 05/30/2018] [Indexed: 01/25/2023]
Abstract
Optical mapping is widely used as a tool to investigate cardiac electrophysiology in ex vivo preparations. Digital filtering of fluorescence-optical data is an important requirement for robust subsequent data analysis and still a challenge when processing data acquired from thin mammalian myocardium. Therefore, we propose and investigate the use of an adaptive spatio-temporal Gaussian filter for processing optical mapping signals from these kinds of tissue usually having low signal-to-noise ratio (SNR). We demonstrate how filtering parameters can be chosen automatically without additional user input. For systematic comparison of this filter with standard filtering methods from the literature, we generated synthetic signals representing optical recordings from atrial myocardium of a rat heart with varying SNR. Furthermore, all filter methods were applied to experimental data from an ex vivo setup. Our developed filter outperformed the other filter methods regarding local activation time detection at SNRs smaller than 3 dB which are typical noise ratios expected in these signals. At higher SNRs, the proposed filter performed slightly worse than the methods from literature. In conclusion, the proposed adaptive spatio-temporal Gaussian filter is an appropriate tool for investigating fluorescence-optical data with low SNR. The spatio-temporal filter parameters were automatically adapted in contrast to the other investigated filters.
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19
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Boukens BJ, Meijborg VMF, Belterman CN, Opthof T, Janse MJ, Schuessler RB, Coronel R, Efimov IR. Local transmural action potential gradients are absent in the isolated, intact dog heart but present in the corresponding coronary-perfused wedge. Physiol Rep 2018; 5:e13251. [PMID: 28554962 PMCID: PMC5449556 DOI: 10.14814/phy2.13251] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 03/20/2017] [Accepted: 03/20/2017] [Indexed: 11/24/2022] Open
Abstract
The left ventricular (LV) coronary‐perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded at the same location in the LV wedge preparation. We also compared electrically recorded and optically obtained ARIs in the LV wedge preparation. Five Langendorff‐perfused canine hearts were paced from the right atrium. Local activation and repolarization times were measured with eight transmural needle electrodes. Subsequently, left ventricular coronary‐perfused wedge preparations were prepared from these hearts while the electrodes remained in place. Three electrodes remained at identical positions as in the intact heart. Both electrograms and optical action potentials were recorded (pacing cycle length 400–4000 msec) and activation and repolarization patterns were analyzed. ARIs found in the subepicardium were shorter than in the subendocardium in the LV wedge preparation but not in the intact heart. The transmural ARI gradient recorded at the cut surface of the wedge was not different from that recorded internally. ARIs recorded internally and at the cut surface in the LV wedge preparation, both correlated with optically recorded action potentials. ARI and RT gradients in the LV wedge preparation differed from those in the intact canine heart, implying that those observations in human LV wedge preparations also should be extrapolated to the intact human heart with caution.
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Affiliation(s)
- Bastiaan J Boukens
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia.,Department of Medical Biology, University of Amsterdam, Amsterdam, The Netherlands
| | - Veronique M F Meijborg
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Netherlands Heart Institute, Holland Heart House, Utrecht, The Netherlands
| | - Charly N Belterman
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
| | - Tobias Opthof
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Physiology, University of Utrecht, Utrecht, The Netherlands
| | - Michiel J Janse
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Ruben Coronel
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
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20
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Gloschat C, Aras K, Gupta S, Faye NR, Zhang H, Syunyaev RA, Pryamonosov RA, Rogers J, Kay MW, Efimov IR. RHYTHM: An Open Source Imaging Toolkit for Cardiac Panoramic Optical Mapping. Sci Rep 2018; 8:2921. [PMID: 29440763 PMCID: PMC5811559 DOI: 10.1038/s41598-018-21333-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/02/2018] [Indexed: 01/05/2023] Open
Abstract
Fluorescence optical imaging techniques have revolutionized the field of cardiac electrophysiology and advanced our understanding of complex electrical activities such as arrhythmias. However, traditional monocular optical mapping systems, despite having high spatial resolution, are restricted to a two-dimensional (2D) field of view. Consequently, tracking complex three-dimensional (3D) electrical waves such as during ventricular fibrillation is challenging as the waves rapidly move in and out of the field of view. This problem has been solved by panoramic imaging which uses multiple cameras to measure the electrical activity from the entire epicardial surface. However, the diverse engineering skill set and substantial resource cost required to design and implement this solution have made it largely inaccessible to the biomedical research community at large. To address this barrier to entry, we present an open source toolkit for building panoramic optical mapping systems which includes the 3D printing of perfusion and imaging hardware, as well as software for data processing and analysis. In this paper, we describe the toolkit and demonstrate it on different mammalian hearts: mouse, rat, and rabbit.
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Affiliation(s)
- Christopher Gloschat
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA
| | - Kedar Aras
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA
| | - Shubham Gupta
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA
| | - N Rokhaya Faye
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA
| | - Hanyu Zhang
- The University of Alabama at Birmingham, Department of Biomedical Engineering, Birmingham, 35294, USA
| | - Roman A Syunyaev
- Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia
| | - Roman A Pryamonosov
- Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia.,Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, 119991, Russia
| | - Jack Rogers
- The University of Alabama at Birmingham, Department of Biomedical Engineering, Birmingham, 35294, USA
| | - Matthew W Kay
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA
| | - Igor R Efimov
- The George Washington University, Department of Biomedical Engineering, Washington, 20052, USA. .,Moscow Institute of Physics and Technology, Dolgoprudny, 141701, Russia.
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21
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Electromechanical optical mapping. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:150-169. [DOI: 10.1016/j.pbiomolbio.2017.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 09/10/2017] [Indexed: 11/23/2022]
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22
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Quinn TA, Jin H, Lee P, Kohl P. Mechanically Induced Ectopy via Stretch-Activated Cation-Nonselective Channels Is Caused by Local Tissue Deformation and Results in Ventricular Fibrillation if Triggered on the Repolarization Wave Edge (Commotio Cordis). Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.116.004777. [PMID: 28794084 PMCID: PMC5555388 DOI: 10.1161/circep.116.004777] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 07/07/2017] [Indexed: 12/11/2022]
Abstract
Supplemental Digital Content is available in the text. Background— External chest impacts (commotio cordis) can cause mechanically induced premature ventricular excitation (PVEM) and, rarely, ventricular fibrillation (VF). Because block of stretch-sensitive ATP-inactivated potassium channels curtailed VF occurrence in a porcine model of commotio cordis, VF has been suggested to arise from abnormal repolarization caused by stretch activation of potassium channels. Alternatively, VF could result from abnormal excitation by PVEM, overlapping with normal repolarization-related electric heterogeneity. Here, we investigate mechanisms and determinants of PVEM induction and its potential role in commotio cordis–induced VF. Methods and Results— Subcontusional mechanical stimuli were applied to isolated rabbit hearts during optical voltage mapping, combined with pharmacological block of ATP-inactivated potassium or stretch-activated cation-nonselective channels. We demonstrate that local mechanical stimulation reliably triggers PVEM at the contact site, with inducibility predicted by local tissue indentation. PVEM induction is diminished by pharmacological block of stretch-activated cation-nonselective channels. In hearts where electrocardiogram T waves involve a well-defined repolarization edge traversing the epicardium, PVEM can reliably provoke VF if, and only if, the mechanical stimulation site overlaps the repolarization wave edge. In contrast, application of short-lived intraventricular pressure surges neither triggers PVEM nor changes repolarization. ATP-inactivated potassium channel block has no effect on PVEM inducibility per se, but shifts it to later time points by delaying repolarization and prolonging refractoriness. Conclusions— Local mechanical tissue deformation determines PVEM induction via stretch-activation of cation-nonselective channels, with VF induction requiring PVEM overlap with the trailing edge of a normal repolarization wave. This defines a narrow, subject-specific vulnerable window for commotio cordis–induced VF that exists both in time and in space.
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Affiliation(s)
- T Alexander Quinn
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.).
| | - Honghua Jin
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
| | - Peter Lee
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
| | - Peter Kohl
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada (T.A.Q.); Department of Physiology, Anatomy, and Genetics, University of Oxford, United Kingdom (H.J., P.L.); and Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical School of the University of Freiburg, Germany (P.K.)
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23
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Kirschner Peretz N, Segal S, Arbel-Ganon L, Ben Jehuda R, Shemer Y, Eisen B, Davoodi M, Binah O, Yaniv Y. A Method Sustaining the Bioelectric, Biophysical, and Bioenergetic Function of Cultured Rabbit Atrial Cells. Front Physiol 2017; 8:584. [PMID: 28860999 PMCID: PMC5559495 DOI: 10.3389/fphys.2017.00584] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Culturing atrial cells leads to a loss in their ability to be externally paced at physiological rates and to maintain their shape. We aim to develop a culture method that sustains the shape of atrial cells along with their biophysical and bioenergetic properties in response to physiological pacing. We hypothesize that adding 2,3-Butanedione 2-monoxime (BDM), which inhibits contraction during the culture period, will preserve these biophysical and bioenergetic properties. Rabbit atrial cells were maintained in culture for 24 h in a medium enriched with a myofilament contraction inhibitor, BDM. The morphology and volume of the cells, including their ability to contract in response to 1–3 Hz electrical pacing, was maintained at the same level as fresh cells. Importantly, the cells could be successfully infected with a GFP adenovirus. Action potentials, Ca2+ transients, and local Ca2+ spark parameters were similar in the cultured and in fresh cells. Finally, these cultured cells' flavoprotein autofluorescence was maintained at a constant level in response to electrical pacing, a response similar to that of fresh cells. Thus, eliminating contraction during the culture period preserves the bioelectric, biophysical and bioenergetic properties of rabbit atrial myocytes. This method therefore has the potential to further improve our understanding of energetic and biochemical regulation in the atria.
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Affiliation(s)
- Noa Kirschner Peretz
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Sofia Segal
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Limor Arbel-Ganon
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ronen Ben Jehuda
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yuval Shemer
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Binyamin Eisen
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Moran Davoodi
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ofer Binah
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
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24
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Ogawa T, Honjo H, Yamazaki M, Kushiyama Y, Sakuma I, Kodama I, Kamiya K. Ranolazine Facilitates Termination of Ventricular Tachyarrhythmia Associated With Acute Myocardial Ischemia Through Suppression of Late I Na-Mediated Focal Activity. Circ J 2017; 81:1411-1428. [PMID: 28552884 DOI: 10.1253/circj.cj-17-0128] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Ventricular tachycardia/fibrillation (VT/VF) associated with acute myocardial ischemia is the most common cause of sudden cardiac death, but its underlying mechanisms are incompletely understood. It is hypothesized that late Na+current (INa) contributes to arrhythmogenic activity in ischemic myocardium.Methods and Results:Langendorff-perfused rabbit hearts with regional ischemia in ventricles were optically mapped. Perfusion with ranolazine (10 μmol/L), a selective inhibitor of lateINa, significantly reduced excitation frequency and facilitated termination of VT/VF induced after occlusion of the left main coronary trunk. The activation pattern during ischemic VT/VF was characterized by breakthrough-type excitations (BEs) from multiple origins, predominantly in the ischemic border zone (BZ) and occasional short-lived rotors. Ranolazine perfusion significantly reduced the incidence of BEs in the BZ. Rotors tended to decrease with progression of ischemia and disappeared after ranolazine perfusion. During constant pacing, ranolazine attenuated ischemia-induced shortening of action potentials in the BZ without affecting conduction velocity, probably due toIKrinhibition. In intact hearts without coronary occlusion, ranolazine (10 μmol/L) terminated aconitine-induced VT by inhibiting focal arrhythmogenic activity in the injection site. CONCLUSIONS LateINa-mediated focal arrhythmogenic activity plays important roles in the maintenance of ischemic VT/VF in isolated rabbit hearts. Suppression of lateINaby ranolazine may be a promising therapeutic strategy to reduce arrhythmic death during the acute phase of myocardial infarction.
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Affiliation(s)
- Takashi Ogawa
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Haruo Honjo
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Yasunori Kushiyama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Ichiro Sakuma
- Graduate School of Engineering, The University of Tokyo
| | - Itsuo Kodama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
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25
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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26
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Hall AR, Hausenloy DJ. Mitochondrial respiratory inhibition by 2,3-butanedione monoxime (BDM): implications for culturing isolated mouse ventricular cardiomyocytes. Physiol Rep 2016; 4:4/1/e12606. [PMID: 26733241 PMCID: PMC4760411 DOI: 10.14814/phy2.12606] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Experiments in isolated ventricular cardiomyocytes have greatly facilitated the study of cellular and subcellular physiology in the heart. However, the isolation and culture of high‐quality adult murine ventricular cardiomyocytes can be technically challenging. In most experimental protocols, the culture of viable adult murine cardiomyocytes for prolonged time periods is achieved with the addition of the myosin II ATPase inhibitors blebbistatin and/or 2,3‐butanedione monoxime (BDM). These drugs are added to increase cell viability and life span by inhibiting spontaneous cardiomyocyte contraction, thereby preventing calcium overload, cell hypercontracture, and cell death. While the addition of BDM has been reported to prolong the life span of isolated adult murine cardiomyocytes, it is also associated with several off‐target effects. Here, we report a novel off‐target effect, in which BDM inhibits mitochondrial respiration by acting directly on the electron transport chain to reduce cell viability. In contrast, when cells were cultured with blebbistatin alone, cells survived for longer, and no metabolic off‐target effects were observed. Based on these novel observations, we recommend that culture media for isolated mouse ventricular cardiomyocytes should be supplemented with blebbistatin alone, as BDM has the potential to affect mitochondrial respiration and cell viability, effects which may impact adversely on subsequent experiments.
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Affiliation(s)
- Andrew R Hall
- The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London Hospital & Medical School, London, UK
| | - Derek J Hausenloy
- The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London Hospital & Medical School, London, UK Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore, Singapore, Singapore National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, Singapore
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27
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Technical advances in studying cardiac electrophysiology - Role of rabbit models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:97-109. [PMID: 27210306 DOI: 10.1016/j.pbiomolbio.2016.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 05/01/2016] [Indexed: 12/15/2022]
Abstract
Cardiovascular research has made a major contribution to an unprecedented 10 year increase in life expectancy during the last 50 years: most of this increase due to a decline in mortality from heart disease and stroke. The majority of the basic cardiovascular science discoveries, which have led to this impressive extension of human life, came from investigations conducted in various small and large animal models, ranging from mouse to pig. The small animal models are currently popular because they are amenable to genetic engineering and are relatively inexpensive. The large animal models are favored at the translational stage of the investigation, as they are anatomically and physiologically more proximal to humans, and can be implanted with various devices; however, they are expensive and less amenable to genetic manipulations. With the advent of CRISPR genetic engineering technology and the advances in implantable bioelectronics, the large animal models will continue to advance. The rabbit model is particularly poised to become one of the most popular among the animal models that recapitulate human heart diseases. Here we review an array of the rabbit models of atrial and ventricular arrhythmias, as well as a range of the imaging and device technologies enabling these investigations.
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28
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Hill YR, Child N, Hanson B, Wallman M, Coronel R, Plank G, Rinaldi CA, Gill J, Smith NP, Taggart P, Bishop MJ. Investigating a Novel Activation-Repolarisation Time Metric to Predict Localised Vulnerability to Reentry Using Computational Modelling. PLoS One 2016; 11:e0149342. [PMID: 26934736 PMCID: PMC4775046 DOI: 10.1371/journal.pone.0149342] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/29/2016] [Indexed: 11/19/2022] Open
Abstract
Exit sites associated with scar-related reentrant arrhythmias represent important targets for catheter ablation therapy. However, their accurate location in a safe and robust manner remains a significant clinical challenge. We recently proposed a novel quantitative metric (termed the Reentry Vulnerability Index, RVI) to determine the difference between activation and repolarisation intervals measured from pairs of spatial locations during premature stimulation to accurately locate the critical site of reentry formation. In the clinic, the method showed potential to identify regions of low RVI corresponding to areas vulnerable to reentry, subsequently identified as ventricular tachycardia (VT) circuit exit sites. Here, we perform an in silico investigation of the RVI metric in order to aid the acquisition and interpretation of RVI maps and optimise its future usage within the clinic. Within idealised 2D sheet models we show that the RVI produces lower values under correspondingly more arrhythmogenic conditions, with even low resolution (8 mm electrode separation) recordings still able to locate vulnerable regions. When applied to models of infarct scars, the surface RVI maps successfully identified exit sites of the reentrant circuit, even in scenarios where the scar was wholly intramural. Within highly complex infarct scar anatomies with multiple reentrant pathways, the identified exit sites were dependent upon the specific pacing location used to compute the endocardial RVI maps. However, simulated ablation of these sites successfully prevented the reentry re-initiation. We conclude that endocardial surface RVI maps are able to successfully locate regions vulnerable to reentry corresponding to critical exit sites during sustained scar-related VT. The method is robust against highly complex and intramural scar anatomies and low resolution clinical data acquisition. Optimal location of all relevant sites requires RVI maps to be computed from multiple pacing locations.
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Affiliation(s)
- Yolanda R. Hill
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Nick Child
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Mikael Wallman
- Department of Systems and Data Analysis, Franhofer-Chalmers Centre, Gothenburg, Sweden
| | - Ruben Coronel
- Academic Medical Center, Amsterdam, Netherlands
- L’Institut de RYthmologieet de Modelisation Cardiaque (LIRYC), Fondation Universite Bordeaux, Bordeaux, France
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Jaswinder Gill
- Department of Cardiology, Guys and St Thomas’ Hospital, London, United Kingdom
| | - Nicolas P. Smith
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- Department of Engineering, University of Auckland, Auckland, New Zealand
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Martin J. Bishop
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- * E-mail:
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29
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Entz M, George SA, Zeitz MJ, Raisch T, Smyth JW, Poelzing S. Heart Rate and Extracellular Sodium and Potassium Modulation of Gap Junction Mediated Conduction in Guinea Pigs. Front Physiol 2016; 7:16. [PMID: 26869934 PMCID: PMC4735342 DOI: 10.3389/fphys.2016.00016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/12/2016] [Indexed: 11/29/2022] Open
Abstract
Background: Recent studies suggested that cardiac conduction in murine hearts with narrow perinexi and 50% reduced connexin43 (Cx43) expression is more sensitive to relatively physiological changes of extracellular potassium ([K+]o) and sodium ([Na+]o). Purpose: Determine whether similar [K+]o and [Na+]o changes alter conduction velocity (CV) sensitivity to pharmacologic gap junction (GJ) uncoupling in guinea pigs. Methods: [K+]o and [Na+]o were varied in Langendorff perfused guinea pig ventricles (Solution A: [K+]o = 4.56 and [Na+]o = 153.3 mM. Solution B: [K+]o = 6.95 and [Na+]o = 145.5 mM). Gap junctions were inhibited with carbenoxolone (CBX) (15 and 30 μM). Epicardial CV was quantified by optical mapping. Perinexal width was measured with transmission electron microscopy. Total and phosphorylated Cx43 were evaluated by western blotting. Results: Solution composition did not alter CV under control conditions or with 15μM CBX. Decreasing the basic cycle length (BCL) of pacing from 300 to 160 ms decreased CV uniformly with both solutions. At 30 μM CBX, a change in solution did not alter CV either longitudinally or transversely at BCL = 300 ms. However, reducing BCL to 160 ms caused CV to decrease more in hearts perfused with Solution B than A. Solution composition did not alter perinexal width, nor did it change total or phosphorylated serine 368 Cx43 expression. These data suggest that the solution dependent CV changes were independent of altered perinexal width or GJ coupling. Action potential duration was always shorter in hearts perfused with Solution B than A, independent of pacing rate and/or CBX concentration. Conclusions: Increased heart rate and GJ uncoupling can unmask small CV differences caused by changing [K+]o and [Na+]o. These data suggest that modulating extracellular ionic composition may be a novel anti-arrhythmic target in diseases with abnormal GJ coupling, particularly when heart rate cannot be controlled.
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Affiliation(s)
- Michael Entz
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA
| | - Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA
| | - Michael J Zeitz
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University Roanoke, VA, USA
| | - Tristan Raisch
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
| | - James W Smyth
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Department of Biological Sciences, College of Science, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Department of Biological Sciences, College of Science, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
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Optical Imaging of Cardiac Action Potential. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:299-311. [PMID: 26238058 DOI: 10.1007/978-3-319-17641-3_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This chapter reviews the major milestones and scientific achievements facilitated by optical imaging of the action potential in the heart over more than four decades since its introduction. We discuss the limitations of this technique, which sometimes are not fully recognized; the unresolved issues, such as motion artifacts, and the newest developments and future directions.
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Everett TH, Hulley GS, Lee KW, Chang R, Wilson EE, Olgin JE. The effects of remodeling with heart failure on mode of initiation of ventricular fibrillation and its spatiotemporal organization. J Interv Card Electrophysiol 2015; 43:205-15. [PMID: 26001644 DOI: 10.1007/s10840-015-0016-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/05/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE The effect of the heart failure substrate on the initiation of ventricular fibrillation (VF) and its resulting mechanism is not known. The objective of this study was to determine the effects of substrate on VF initiation and its spatiotemporal organization in the heart failure model. METHODS Optical action potentials were recorded from LV wedge preparations either from structurally normal hearts (control, n = 11) or from congestive heart failure (CHF; n = 7), at the epicardial surface, endocardial surface which included a papillary muscle, and a transmural cross section. Action potential duration (APD(80)) was determined, and VF was initiated. A fast Fourier transform was calculated, and the dominant frequency (DF) was determined. RESULTS The CHF group showed increased VF vulnerability (69 vs 26 %, p < 0.03), and every mapped surface showed an APD(80) gradient which included islands of higher APDs on the transmural surface (M cells) which was not observed in controls. VF in the CHF group was characterized by stable, discrete, high-DF areas that correlated to either foci or spiral waves located on the transmural surface at the site of the papillary muscle. Overall, the top 10 % of DFs correlated to an APD of 101 ms while the bottom 10 % of DFs correlated to an APD of 126 ms (p < 0.01). CONCLUSIONS In the CHF model, APD gradients correlated with an increased vulnerability to VF, and the highest stable DFs were located on the transmural surface which was not seen in controls. This indicates that the CHF substrate creates unique APD and DF characteristics.
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Affiliation(s)
- Thomas H Everett
- Krannert Institute of Cardiology, Indiana University School of Medicine, 1800 N. Capitol, Ste. E400E, Indianapolis, IN, 46202, USA,
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Garg V, Taylor T, Warren M, Venable P, Sciuto K, Shibayama J, Zaitsev A. β-Adrenergic stimulation and rapid pacing mutually promote heterogeneous electrical failure and ventricular fibrillation in the globally ischemic heart. Am J Physiol Heart Circ Physiol 2015; 308:H1155-70. [PMID: 25713306 PMCID: PMC4551128 DOI: 10.1152/ajpheart.00768.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/16/2015] [Indexed: 01/09/2023]
Abstract
Global ischemia, catecholamine surge, and rapid heart rhythm (RHR) due to ventricular tachycardia or ventricular fibrillation (VF) are the three major factors of sudden cardiac arrest (SCA). Loss of excitability culminating in global electrical failure (asystole) is the major adverse outcome of SCA with increasing prevalence worldwide. The roles of catecholamines and RHR in the electrical failure during SCA remain unclear. We hypothesized that both β-adrenergic stimulation (βAS) and RHR accelerate electrical failure in the globally ischemic heart. We performed optical mapping of the action potential (OAP) in the right ventricular (RV) and left (LV) ventricular epicardium of isolated rabbit hearts subjected to 30-min global ischemia. Hearts were paced at a cycle length of either 300 or 200 ms, and either in the presence or in the absence of β-agonist isoproterenol (30 nM). 2,3-Butanedione monoxime (20 mM) was used to reduce motion artifact. We found that RHR and βAS synergistically accelerated the decline of the OAP upstroke velocity and the progressive expansion of inexcitable regions. Under all conditions, inexcitability developed faster in the LV than in the RV. At the same time, both RHR and βAS shortened the time to VF (TVF) during ischemia. Moreover, the time at which 10% of the mapped LV area became inexcitable strongly correlated with TVF (R(2) = 0 .72, P < 0.0001). We conclude that both βAS and RHR are major factors of electrical depression and failure in the globally ischemic heart and may contribute to adverse outcomes of SCA such as asystole and recurrent/persistent VF.
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Affiliation(s)
- Vivek Garg
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Tyson Taylor
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Bioengineering, University of Utah, Salt Lake City, Utah; and
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Bioengineering, University of Utah, Salt Lake City, Utah; and
| | - Paul Venable
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Bioengineering, University of Utah, Salt Lake City, Utah; and
| | - Katie Sciuto
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Bioengineering, University of Utah, Salt Lake City, Utah; and
| | - Junko Shibayama
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Internal Medicine, School of Medicine, University of Utah, Salt Lake City, Utah
| | - Alexey Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah; Department of Bioengineering, University of Utah, Salt Lake City, Utah; and
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Hammer KP, Ljubojevic S, Ripplinger CM, Pieske BM, Bers DM. Cardiac myocyte alternans in intact heart: Influence of cell-cell coupling and β-adrenergic stimulation. J Mol Cell Cardiol 2015; 84:1-9. [PMID: 25828762 DOI: 10.1016/j.yjmcc.2015.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/12/2015] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cardiac alternans are proarrhythmic and mechanistically link cardiac mechanical dysfunction and sudden cardiac death. Beat-to-beat alternans occur when beats with large Ca(2+) transients and long action potential duration (APD) alternate with the converse. APD alternans are typically driven by Ca(2+) alternans and sarcoplasmic reticulum (SR) Ca(2+) release alternans. But the effect of intercellular communication via gap junctions (GJ) on alternans in the intact heart remains unknown. OBJECTIVE We assessed the effects of cell-to-cell coupling on local alternans in intact Langendorff-perfused mouse hearts, measuring single myocyte [Ca(2+)] alternans synchronization among neighboring cells, and effects of β-adrenergic receptor (β-AR) activation and reduced GJ coupling. METHODS AND RESULTS Mouse hearts (C57BL/6) were retrogradely perfused and loaded with Fluo8-AM to record cardiac myocyte [Ca(2+)] in situ with confocal microscopy. Single cell resolution allowed analysis of alternans within the intact organ during alternans induction. Carbenoxolone (25 μM), a GJ inhibitor, significantly increased the occurrence and amplitude of alternans in single cells within the intact heart. Alternans were concordant between neighboring cells throughout the field of view, except transiently during onset. β-AR stimulation only reduced Ca(2+) alternans in tissue that had reduced GJ coupling, matching effects seen in isolated myocytes. CONCLUSIONS Ca(2+) alternans among neighboring myocytes is predominantly concordant, likely because of electrical coupling between cells. Consistent with this, partial GJ uncoupling increased propensity and amplitude of Ca(2+) alternans, and made them more sensitive to reversal by β-AR activation, as in isolated myocytes. Electrical coupling between myocytes may thus limit the alternans initiation, but also allow alternans to be more stable once established.
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Affiliation(s)
- Karin P Hammer
- Department of Pharmacology, University of California, Davis, GBSF, Davis, CA 95616-8636, USA.
| | - Senka Ljubojevic
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8010 Graz, Austria.
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, GBSF, Davis, CA 95616-8636, USA.
| | - Burkert M Pieske
- Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8010 Graz, Austria; Department of Cardiology, Charité - Medical University Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany.
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, GBSF, Davis, CA 95616-8636, USA.
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Venable PW, Sciuto KJ, Warren M, Taylor TG, Garg V, Shibayama J, Zaitsev AV. Mitochondrial depolarization and asystole in the globally ischemic rabbit heart: coordinated response to interventions affecting energy balance. Am J Physiol Heart Circ Physiol 2015; 308:H485-99. [PMID: 25552307 PMCID: PMC4346765 DOI: 10.1152/ajpheart.00257.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 12/18/2014] [Indexed: 01/25/2023]
Abstract
Mitochondrial membrane potential (ΔΨm) depolarization has been implicated in the loss of excitability (asystole) during global ischemia, which is relevant for the success of defibrillation and resuscitation after cardiac arrest. However, the relationship between ΔΨm depolarization and asystole during no-flow ischemia remains unknown. We applied spatial Fourier analysis to confocally recorded fluorescence emitted by ΔΨm-sensitive dye tetramethylrhodamine methyl ester. The time of ischemic ΔΨm depolarization (tmito_depol) was defined as the time of 50% decrease in the magnitude of spectral peaks reflecting ΔΨm. The time of asystole (tasys) was determined as the time when spontaneous and induced ventricular activity ceased to exist. Interventions included tachypacing (150 ms), myosin II ATPase inhibitor blebbistatin (heart immobilizer), and the combination of blebbistatin and the inhibitor of glycolysis iodoacetate. In the absence of blebbistatin, confocal images were obtained during brief perfusion with hyperkalemic solution and after the contraction failed between 7 and 15 min of ischemia. In control, tmito_depol and tasys were 24.4 ± 6.0 and 26.0 ± 5.0 min, respectively. Tachypacing did not significantly affect either parameter. Blebbistatin dramatically delayed tmito_depol and tasys (51.4 ± 8.6 and 45.7 ± 5.3 min, respectively; both P < 0.0001 vs. control). Iodoacetate combined with blebbistatin accelerated both events (tmito_depol, 12.7 ± 1.8 min; and tasys, 6.5 ± 1.1 min; both P < 0.03 vs. control). In all groups pooled together, tasys was strongly correlated with tmito_depol (R(2) = 0.845; P < 0.0001). These data may indicate a causal relationship between ΔΨm depolarization and asystole or a similar dependence of the two events on energy depletion during ischemia. Our results urge caution against the use of blebbistatin in studies addressing pathophysiology of myocardial ischemia.
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Affiliation(s)
- Paul W Venable
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Katie J Sciuto
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Tyson G Taylor
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Vivek Garg
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Junko Shibayama
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
| | - Alexey V Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
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Imaging of Ventricular Fibrillation and Defibrillation: The Virtual Electrode Hypothesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:343-65. [PMID: 26238060 DOI: 10.1007/978-3-319-17641-3_14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Ventricular fibrillation is the major underlying cause of sudden cardiac death. Understanding the complex activation patterns that give rise to ventricular fibrillation requires high resolution mapping of localized activation. The use of multi-electrode mapping unraveled re-entrant activation patterns that underlie ventricular fibrillation. However, optical mapping contributed critically to understanding the mechanism of defibrillation, where multi-electrode recordings could not measure activation patterns during and immediately after a shock. In addition, optical mapping visualizes the virtual electrodes that are generated during stimulation and defibrillation pulses, which contributed to the formulation of the virtual electrode hypothesis. The generation of virtual electrode induced phase singularities during defibrillation is arrhythmogenic and may lead to the induction of fibrillation subsequent to defibrillation. Defibrillating with low energy may circumvent this problem. Therefore, the current challenge is to use the knowledge provided by optical mapping to develop a low energy approach of defibrillation, which may lead to more successful defibrillation.
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Abstract
In a normal human life span, the heart beats about 2 to 3 billion times. Under diseased conditions, a heart may lose its normal rhythm and degenerate suddenly into much faster and irregular rhythms, called arrhythmias, which may lead to sudden death. The transition from a normal rhythm to an arrhythmia is a transition from regular electrical wave conduction to irregular or turbulent wave conduction in the heart, and thus this medical problem is also a problem of physics and mathematics. In the last century, clinical, experimental, and theoretical studies have shown that dynamical theories play fundamental roles in understanding the mechanisms of the genesis of the normal heart rhythm as well as lethal arrhythmias. In this article, we summarize in detail the nonlinear and stochastic dynamics occurring in the heart and their links to normal cardiac functions and arrhythmias, providing a holistic view through integrating dynamics from the molecular (microscopic) scale, to the organelle (mesoscopic) scale, to the cellular, tissue, and organ (macroscopic) scales. We discuss what existing problems and challenges are waiting to be solved and how multi-scale mathematical modeling and nonlinear dynamics may be helpful for solving these problems.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Correspondence to: Zhilin Qu, PhD, Department of Medicine, Division of Cardiology, David Geffen School of Medicine at UCLA, A2-237 CHS, 650 Charles E. Young Drive South, Los Angeles, CA 90095, Tel: 310-794-6050, Fax: 310-206-9133,
| | - Gang Hu
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Alan Garfinkel
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California 90095, USA
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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Dura M, Schröder-Schetelig J, Luther S, Lehnart SE. Toward panoramic in situ mapping of action potential propagation in transgenic hearts to investigate initiation and therapeutic control of arrhythmias. Front Physiol 2014; 5:337. [PMID: 25249982 PMCID: PMC4157545 DOI: 10.3389/fphys.2014.00337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/19/2014] [Indexed: 11/23/2022] Open
Abstract
To investigate the dynamics and propensity for arrhythmias in intact transgenic hearts comprehensively, optical strategies for panoramic fluorescence imaging of action potential (AP) propagation are essential. In particular, mechanism-oriented molecular studies usually depend on transgenic mouse hearts of only a few millimeters in size. Furthermore, the temporal scales of the mouse heart remain a challenge for panoramic fluorescence imaging with heart rates ranging from 200 min−1 (e.g., depressed sinus node function) to over 1200 min−1 during fast arrhythmias. To meet these challenging demands, we and others developed physiologically relevant mouse models and characterized their hearts with planar AP mapping. Here, we summarize the progress toward panoramic fluorescence imaging and its prospects for the mouse heart. In general, several high-resolution cameras are synchronized and geometrically arranged for panoramic voltage mapping and the surface and blood vessel anatomy documented through image segmentation and heart surface reconstruction. We expect that panoramic voltage imaging will lead to novel insights about molecular arrhythmia mechanisms through quantitative strategies and organ-representative analysis of intact mouse hearts.
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Affiliation(s)
- Miroslav Dura
- Heart Research Center Göttingen Göttingen, Germany ; Department of Cardiology and Pulmonology, University Medical Center Göttingen Göttingen, Germany
| | - Johannes Schröder-Schetelig
- Heart Research Center Göttingen Göttingen, Germany ; Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization Göttingen, Germany ; Institute for Nonlinear Dynamics, Georg-August-Universität Göttingen Göttingen, Germany
| | - Stefan Luther
- Heart Research Center Göttingen Göttingen, Germany ; Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization Göttingen, Germany ; Institute for Nonlinear Dynamics, Georg-August-Universität Göttingen Göttingen, Germany ; German Centre for Cardiovascular Research (DZHK), partner site Göttingen (DZHK-GOE) Göttingen, Germany
| | - Stephan E Lehnart
- Heart Research Center Göttingen Göttingen, Germany ; Department of Cardiology and Pulmonology, University Medical Center Göttingen Göttingen, Germany ; German Centre for Cardiovascular Research (DZHK), partner site Göttingen (DZHK-GOE) Göttingen, Germany
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Seo K, Inagaki M, Hidaka I, Fukano H, Sugimachi M, Hisada T, Nishimura S, Sugiura S. Relevance of cardiomyocyte mechano-electric coupling to stretch-induced arrhythmias: optical voltage/calcium measurement in mechanically stimulated cells, tissues and organs. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:129-39. [PMID: 25084395 DOI: 10.1016/j.pbiomolbio.2014.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/19/2014] [Indexed: 12/27/2022]
Abstract
Stretch-induced arrhythmias are multi-scale phenomena in which alterations in channel activities and/or calcium handling lead to the organ level derangement of the heart rhythm. To understand how cellular mechano-electric coupling (MEC) leads to stretch-induced arrhythmias at the organ level, we developed stretching devices and optical voltage/calcium measurement techniques optimized to each cardiac level. This review introduces these experimental techniques of (1) optical voltage measurement coupled with a carbon-fiber technique for single isolated cardiomyocytes, (2) optical voltage mapping combined with motion tracking technique for myocardial tissue/whole heart preparations and (3) real-time calcium imaging coupled with a laser optical trap technique for cardiomyocytes. Following the overview of each methodology, results are presented. We conclude that individual MEC in cardiomyocytes can be heterogeneous at the ventricular level, especially when moderate amplitude mechanical stretches are applied to the heart, and that this heterogeneous MEC can evoke focal excitation that develops into re-entrant arrhythmias.
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Affiliation(s)
- Kinya Seo
- Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.
| | - Masashi Inagaki
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan.
| | - Ichiro Hidaka
- Division of Physical and Health Education, Graduate School of Education, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Hana Fukano
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center Research Institute, Osaka 565-0873, Japan.
| | - Toshiaki Hisada
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
| | - Satoshi Nishimura
- Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan; Department of Cardiovascular Medicine, Translational Systems Biology and Medicine Initiative, The University of Tokyo, Tokyo 113-8655, Japan.
| | - Seiryo Sugiura
- Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan.
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Li D, Wu J, Bai Y, Zhao X, Liu L. Isolation and culture of adult mouse cardiomyocytes for cell signaling and in vitro cardiac hypertrophy. J Vis Exp 2014. [PMID: 24894542 DOI: 10.3791/51357] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Technological advances have made genetically modified mice, including transgenic and gene knockout mice, an essential tool in many research fields. Adult cardiomyocytes are widely accepted as a good model for cardiac cellular physiology and pathophysiology, as well as for pharmaceutical intervention. Genetically modified mice preclude the need for complicated cardiomyocyte infection processes to generate the desired genotype, which are inefficient due to cardiomyocytes' terminal differentiation. Isolation and culture of high quantity and quality functional cardiomyocytes will dramatically benefit cardiovascular research and provide an important tool for cell signaling transduction research and drug development. Here, we describe a well-established method for isolation of adult mouse cardiomyocytes that can be implemented with little training. The mouse heart is excised and cannulated to an isolated heart system, then perfused with a calcium-free and high potassium buffer followed by type II collagenase digestion in Langendorff retrograde perfusion mode. This protocol yields a consistent result for the collection of functional adult mouse cardiomyocytes from a variety of genetically modified mice.
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Affiliation(s)
- Daxiang Li
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine and Life Sciences
| | - Jian Wu
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine and Life Sciences
| | - Yan Bai
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine and Life Sciences
| | - Xiaochen Zhao
- Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences
| | - Lijun Liu
- Department of Biochemistry and Cancer Biology, University of Toledo College of Medicine and Life Sciences;
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40
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Xu L, Gutbrod SR, Bonifas AP, Su Y, Sulkin MS, Lu N, Chung HJ, Jang KI, Liu Z, Ying M, Lu C, Webb RC, Kim JS, Laughner JI, Cheng H, Liu Y, Ameen A, Jeong JW, Kim GT, Huang Y, Efimov IR, Rogers JA. 3D multifunctional integumentary membranes for spatiotemporal cardiac measurements and stimulation across the entire epicardium. Nat Commun 2014; 5:3329. [PMID: 24569383 DOI: 10.1038/ncomms4329] [Citation(s) in RCA: 295] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 01/27/2014] [Indexed: 01/07/2023] Open
Abstract
Means for high-density multiparametric physiological mapping and stimulation are critically important in both basic and clinical cardiology. Current conformal electronic systems are essentially 2D sheets, which cannot cover the full epicardial surface or maintain reliable contact for chronic use without sutures or adhesives. Here we create 3D elastic membranes shaped precisely to match the epicardium of the heart via the use of 3D printing, as a platform for deformable arrays of multifunctional sensors, electronic and optoelectronic components. Such integumentary devices completely envelop the heart, in a form-fitting manner, and possess inherent elasticity, providing a mechanically stable biotic/abiotic interface during normal cardiac cycles. Component examples range from actuators for electrical, thermal and optical stimulation, to sensors for pH, temperature and mechanical strain. The semiconductor materials include silicon, gallium arsenide and gallium nitride, co-integrated with metals, metal oxides and polymers, to provide these and other operational capabilities. Ex vivo physiological experiments demonstrate various functions and methodological possibilities for cardiac research and therapy.
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Affiliation(s)
- Lizhi Xu
- 1] Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA [2]
| | - Sarah R Gutbrod
- 1] Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA [2]
| | - Andrew P Bonifas
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Yewang Su
- 1] Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA [2] Center for Mechanics and Materials, Tsinghua University, Beijing 100084, China
| | - Matthew S Sulkin
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA
| | - Nanshu Lu
- Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Hyun-Joong Chung
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4
| | - Kyung-In Jang
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Zhuangjian Liu
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Ming Ying
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Chi Lu
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - R Chad Webb
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Jong-Seon Kim
- 1] Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA [2] Department of Chemical and Biomolecular Engineering (BK21 Program), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Jacob I Laughner
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA
| | - Huanyu Cheng
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Yuhao Liu
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Abid Ameen
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Jae-Woong Jeong
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Gwang-Tae Kim
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Yonggang Huang
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Igor R Efimov
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA
| | - John A Rogers
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Bishop MJ, Burton RAB, Kalla M, Nanthakumar K, Plank G, Bub G, Vigmond EJ. Mechanism of reentry induction by a 9-V battery in rabbit ventricles. Am J Physiol Heart Circ Physiol 2014; 306:H1041-53. [PMID: 24464758 DOI: 10.1152/ajpheart.00591.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the application of a 9-V battery to the epicardial surface is a simple method of ventricular fibrillation induction, the fundamental mechanisms underlying this process remain unstudied. We used a combined experimental and modelling approach to understand how the interaction of direct current (DC) from a battery may induce reentrant activity within rabbit ventricles and its dependence on battery application timing and duration. A rabbit ventricular computational model was used to simulate 9-V battery stimulation for different durations at varying onset times during sinus rhythm. Corresponding high-resolution optical mapping measurements were conducted on rabbit hearts with DC stimuli applied via a relay system. DC application to diastolic tissue induced anodal and cathodal make excitations in both simulations and experiments. Subsequently, similar static epicardial virtual electrode patterns were formed that interacted with sinus beats but did not induce reentry. Upon battery release during diastole, break excitations caused single ectopics, similar to application, before sinus rhythm resumed. Reentry induction was possible for short battery applications when break excitations were slowed and forced to take convoluted pathways upon interaction with refractory tissue from prior make excitations or sinus beats. Short-lived reentrant activity could be induced for battery release shortly after a sinus beat for longer battery applications. In conclusion, the application of a 9-V battery to the epicardial surface induces reentry through a complex interaction of break excitations after battery release with prior induced make excitations or sinus beats.
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Affiliation(s)
- Martin J Bishop
- Department of Biomedical Engineering, King's College London, London, United Kingdom
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Azer J, Hua R, Krishnaswamy PS, Rose RA. Effects of natriuretic peptides on electrical conduction in the sinoatrial node and atrial myocardium of the heart. J Physiol 2013; 592:1025-45. [PMID: 24344164 DOI: 10.1113/jphysiol.2013.265405] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Natriuretic peptides, including B-type and C-type natriuretic peptide (BNP and CNP), are powerful regulators of the cardiovascular system; however, their electrophysiological effects in the heart, particularly in the sinoatrial node (SAN), are incompletely understood. We have used high-resolution optical mapping to measure the effects of BNP and CNP, and the roles of natriuretic peptide receptors (NPR-A, NPR-B and NPR-C), on electrical conduction within the SAN and atrial myocardium. In basal conditions BNP and CNP (50-500 nm) increased conduction velocity (CV) within the SAN by ∼30% at the high dose and shifted the initial exit site superiorly. These effects sped conduction from the SAN to the surrounding atrial myocardium and were mediated by the NPR-A and NPR-B receptors. In the presence of isoproterenol (1 μm) the NPR-C receptor made a major contribution to the effects of BNP and CNP in the heart. In these conditions BNP, CNP and the NPR-C agonist cANF each decreased SAN CV and shifted the initial exit site inferiorly. The effects of cANF (30% reduction) were larger than BNP or CNP (∼15% reduction), indicating that BNP and CNP activate multiple natriuretic peptide receptors. In support of this, the inhibitory effects of BNP were absent in NPR-C knockout mice, where BNP instead elicited a further increase (∼25%) in CV. Measurements in externally paced atrial preparations demonstrate that the effects of natriuretic peptides on CV are partially independent of changes in cycle length. These data provide detailed novel insight into the complex effects of natriuretic peptides and their receptors on electrical conduction in the heart.
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Affiliation(s)
- John Azer
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building - Room 4J, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2.
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Abstract
In the past decade, optical mapping provided crucial mechanistic insight into electromechanical function and the mechanism of ventricular fibrillation. Therefore, to date, optical mapping dominates experimental cardiac electrophysiology. The first cardiac measurements involving optics were done in the early 1900s using the fast cinematograph that later evolved into methods for high-resolution activation and repolarization mapping and stimulation of specific cardiac cell types. The field of "optocardiography," therefore, emerged as the use of light for recording or interfering with cardiac physiology. In this review, we discuss how optocardiography developed into the dominant research technique in experimental cardiology. Furthermore, we envision how optocardiographic methods can be used in clinical cardiology.
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Matthews GDK, Guzadhur L, Sabir IN, Grace AA, Huang CLH. Action potential wavelength restitution predicts alternans and arrhythmia in murine Scn5a(+/-) hearts. J Physiol 2013; 591:4167-88. [PMID: 23836691 PMCID: PMC3779110 DOI: 10.1113/jphysiol.2013.254938] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Reductions in cardiac action potential wavelength, and the consequent wavebreak, have been implicated in arrhythmogenesis. Tachyarrhythmias are more common in the Brugada syndrome, particularly following pharmacological challenge, previously modelled using Scn5a+/− murine hearts. Propagation latencies and action potential durations (APDs) from monophasic action potential recordings were used to assess wavelength changes with heart rate in Langendorff-perfused wild-type (WT) and Scn5a+/− hearts. Recordings were obtained from right (RV) and left (LV) ventricular, epicardial and endocardial surfaces during incremental pacing, before and following flecainide or quinidine challenge. Conduction velocities (θ′), action potential wavelengths (λ′= APD ×θ′), and their corresponding alternans depended non-linearly upon diastolic interval (DI). Maximum θ′ was lower in Scn5a+/− RV epicardium than endocardium. Flecainide further reduced θ′, accentuating this RV conduction block. Quinidine reduced maximum θ′ in WT and caused earlier conduction failure in the RV of both Scn5a+/− and WT. Use of recovery wavelengths (λ′0= DI ×θ′) rather than DI, provided novel λ restitution plots of λ′ against λ′0, which sum to a basic cycle distance permitting feedback analysis. λ′ restitution gradient better correlated with alternans magnitude than either APD or θ restitution gradient. The large differences in θ′ and APD restitution contrasted with minor differences in maximum λ′ between epi- and endocardia of untreated hearts, and quinidine-treated WT hearts. Strikingly, all regions and conditions converged to a common instability point, implying a conserved relationship. Flecainide or quinidine decreased the pacing rates at which this occurred, through reducing basic cycle distance, in the Scn5a+/− RV epicardium, directly predictive of its arrhythmic phenotype.
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Affiliation(s)
- Gareth D K Matthews
- G. D. K. Matthews: Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
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Venkataraman R, Baldo MP, Hwang HS, Veltri T, Pinto JR, Baudenbacher FJ, Knollmann BC. Myofilament calcium de-sensitization and contractile uncoupling prevent pause-triggered ventricular tachycardia in mouse hearts with chronic myocardial infarction. J Mol Cell Cardiol 2013; 60:8-15. [PMID: 23570978 PMCID: PMC3683590 DOI: 10.1016/j.yjmcc.2013.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/11/2013] [Accepted: 03/30/2013] [Indexed: 11/16/2022]
Abstract
Myocardial infarction (MI) is a major risk for ventricular arrhythmia. Pause-triggered ventricular arrhythmia can be caused by increased myofilament Ca binding due to sarcomeric mutations or Ca-sensitizing compounds. Myofilament Ca sensitivity is also increased after MI. Here we hypothesize that MI increases risk for pause-triggered ventricular arrhythmias, which can be prevented by myofilament Ca-desensitization and contractile uncoupling. To test this hypothesis, we generated a murine chronic MI model using male B6SJLF1/J mice (n=40) that underwent permanent ligation of the left anterior descending coronary artery. 4 weeks post MI, cardiac structure, function and myofilament Ca sensitivity were evaluated. Pause-dependent arrhythmia susceptibility was quantified in isolated hearts with pacing trains of increasing frequency, followed by a pause and an extra stimulus. Coronary ligation resulted in a mean infarct size of 39.6±5.7% LV and fractional shortening on echocardiography was reduced by 40% compared to non-infarcted controls. Myofilament Ca sensitivity was significantly increased in post MI hearts (pCa50: Control=5.66±0.03; MI=5.84±0.05; P<0.01). Exposure to the Ca desensitizer/contractile uncoupler blebbistatin (BLEB, 3 μM) reduced myofilament Ca sensitivity of MI hearts to that of control hearts and selectively reduced the frequency of post-pause ectopic beats (MI 0.12±0.04 vs MI+BLEB 0.01±0.005 PVC/pause; P=0.02). BLEB also reduced the incidence of ventricular tachycardia in chronic MI hearts from 59% to 10% (P<0.05). We conclude that chronic MI hearts exhibit increased myofilament Ca sensitivity and pause-triggered ventricular arrhythmias, which can be prevented by blebbistatin. Decreasing myofilament Ca sensitivity may be a strategy to reduce arrhythmia burden after MI.
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Affiliation(s)
- Raghav Venkataraman
- Department of Biomedical Engineering and Physics, Vanderbilt University, Nashville, TN 37232-0575, USA
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46
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Synthesis, solid state and solution studies of cobalt(II) complexes with 2-hydroxyiminopropanoic acid. Polyhedron 2013. [DOI: 10.1016/j.poly.2013.03.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Smith RM, Visweswaran R, Talkachova I, Wothe JK, Tolkacheva EG. Uncoupling the mitochondria facilitates alternans formation in the isolated rabbit heart. Am J Physiol Heart Circ Physiol 2013; 305:H9-18. [PMID: 23645464 DOI: 10.1152/ajpheart.00915.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alternans of action potential duration (APD) and intracellular calcium ([Ca²⁺]i) transients in the whole heart are thought to be markers of increased propensity to ventricular fibrillation during ischemia-reperfusion injuries. During ischemia, ATP production is affected and the mitochondria become uncoupled, which may affect alternans formation in the heart. The aim of our study was to investigate the role of mitochondria on the formation of APD and [Ca²⁺]i alternans in the isolated rabbit heart. We performed dual voltage and [Ca²⁺]i optical mapping of isolated rabbit hearts under control conditions, global no-flow ischemia (n = 6), and after treatment with 50 nM of the mitochondrial uncoupler FCCP (n = 6). We investigated the formation of alternans of APD, [Ca²⁺]i amplitude (CaA), and [Ca²⁺]i duration (CaD) under different rates of pacing. We found that treatment with FCCP leads to the early occurrence of APD, CaD, and CaA alternans; an increase of intraventricular APD but not CaD heterogeneity; and significant reduction in conduction velocity compared with that of control. Furthermore, we demonstrated that FCCP and global ischemia have similar effects on the prolongation of [Ca²⁺]i transients, whereas ischemia induces a significantly larger reduction of APD compared with that in FCCP treatment. In conclusion, our results demonstrate that uncoupling of mitochondria leads to an earlier occurrence of alternans in the heart. Thus, in conditions of mitochondrial stress, as seen during myocardial ischemia, uncoupled mitochondria may be responsible for the formation of both APD and [Ca²⁺]i alternans in the heart, which in turn creates a substrate for ventricular arrhythmias.
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Affiliation(s)
- Rebecca M Smith
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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Bishop MJ, Vigmond EJ, Plank G. The functional role of electrophysiological heterogeneity in the rabbit ventricle during rapid pacing and arrhythmias. Am J Physiol Heart Circ Physiol 2013; 304:H1240-52. [PMID: 23436328 PMCID: PMC3652087 DOI: 10.1152/ajpheart.00894.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electrophysiological heterogeneity in action potential recordings from healthy intact hearts remains highly variable and, where present, is almost entirely abolished at fast pacing rates. Consequently, the functional importance of intrinsic action potential duration (APD) heterogeneity in healthy ventricles, and particularly its role during rapidly activating reentrant arrhythmias, remain poorly understood. By incorporating both transmural and apicobasal APD heterogeneity within a biventricular rabbit computational model and comparing with an equivalent homogeneous model, we directly investigated the functional importance of intrinsic APD heterogeneity under fast pacing and arrhythmogenic protocols. Although differences in APD were significantly modulated at the tissue level during pacing and further reduced as pacing frequency increased, small differences were still noticeable. Such differences were further marginally accentuated/attenuated via electrotonic effects relative to wavefront propagation directions. The remaining small levels of APD heterogeneity under the fastest pacing frequencies resulted in arrhythmia initiation via heterogeneous conduction block, in contrast to complete block in the homogeneous model. Such induction mechanisms were more evident during premature stimuli at slower paced rhythms where intrinsic heterogeneity remained to a greater degree. During sustained arrhythmias, however, intrinsic heterogeneity made little difference to overall reentrant behavior, either visually, or in terms of duration, metrics quantifying filament/phase singularity dynamics, and global electrocardiogram characteristics. These findings suggest that, despite being important during arrhythmia initiation, intrinsic electrophysiological heterogeneity plays little functional role during rapid pacing and sustained arrhythmia dynamics in the healthy ventricle and thus questions the need to incorporate such detail in computational models when simulating rapid arrhythmias.
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Affiliation(s)
- Martin J Bishop
- Biomedical Engineering Department, Division of Imaging Sciences, King's College London, London, United Kingdom.
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Xie C, Biary N, Tocchetti CG, Aon MA, Paolocci N, Kauffman J, Akar FG. Glutathione oxidation unmasks proarrhythmic vulnerability of chronically hyperglycemic guinea pigs. Am J Physiol Heart Circ Physiol 2013; 304:H916-26. [PMID: 23376824 DOI: 10.1152/ajpheart.00026.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Chronic hyperglycemia in type-1 diabetes mellitus is associated with oxidative stress (OS) and sudden death. Mechanistic links remain unclear. We investigated changes in electrophysiological (EP) properties in a model of chronic hyperglycemia before and after challenge with OS by GSH oxidation and tested reversibility of EP remodeling by insulin. Guinea pigs survived for 1 mo following streptozotocin (STZ) or saline (sham) injection. A treatment group received daily insulin for 2 wk to reverse STZ-induced hyperglycemia (STZ + Ins). EP properties were measured using high-resolution optical action potential mapping before and after challenge of hearts with diamide. Despite elevation of glucose levels in STZ compared with sham-operated (P = 0.004) and STZ + Ins (P = 0.002) animals, average action potential duration (APD) and arrhythmia propensity were not altered at baseline. Diamide promoted early (<10 min) formation of arrhythmic triggers reflected by a higher arrhythmia scoring index in STZ (P = 0.045) and STZ + Ins (P = 0.033) hearts compared with sham-operated hearts. APD heterogeneity underwent a more pronounced increase in response to diamide in STZ and STZ + Ins hearts compared with sham-operated hearts. Within 30 min, diamide resulted in spontaneous incidence of ventricular tachycardia and ventricular fibrillation (VT/VF) in 3/6, 2/5, 1/5, and 0/4 STZ, STZ + Ins, sham-operated, and normal hearts, respectively. Hearts prone to VT/VF exhibited greater APD heterogeneity (P = 0.010) compared with their VT/VF-free counterparts. Finally, altered EP properties in STZ were not rescued by insulin. In conclusion, GSH oxidation enhances APD heterogeneity and increases arrhythmia scoring index in a guinea pig model of chronic hyperglycemia. Despite normalization of glycemic levels by insulin, these proarrhythmic properties are not reversed, suggesting the importance of targeting antioxidant defenses for arrhythmia suppression.
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Affiliation(s)
- Chaoqin Xie
- Cardiovascular Institute, Mount Sinai School of Medicine, New York, NY 10029, USA
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50
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Brack KE, Narang R, Winter J, Ng GA. The mechanical uncoupler blebbistatin is associated with significant electrophysiological effects in the isolated rabbit heart. Exp Physiol 2013; 98:1009-27. [PMID: 23291912 PMCID: PMC3734628 DOI: 10.1113/expphysiol.2012.069369] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Blebbistatin (BS) is a recently discovered inhibitor of the myosin II isoform and has been adopted as the mechanical uncoupler of choice for optical mapping, because previous studies suggest that BS has no significant cardiac electrophysiological effects in a number of species. The aim of this study was to determine whether BS affects cardiac electrophysiology in isolated New Zealand White rabbit hearts. Langendorff-perfused hearts (n= 39) in constant-flow mode had left ventricular monophasic action potential duration (MAPD) measured at apical and basal regions during constant pacing (300 ms cycle length). Standard action potential duration restitution was obtained using the single extrastimulus method with measurement of the maximal restitution slope. Ventricular fibrillation threshold was measured as the minimal current inducing sustained ventricular fibrillation with burst pacing (30 stimuli, at 30 ms intervals). Optical action potentials were recorded using the voltage-sensitive dye di-4-ANEPPS. Measurements were taken at baseline and after 60 min perfusion with BS (5 μm). Blebbistatin significantly prolonged left ventricular apical (mean ± SEM; from 129.9 ± 2.9 to 170.7 ± 4.1 ms, P < 0.001, n= 8) and basal MAPD (from 135.0 ± 2.3 to 163.3 ± 5.6 ms, P < 0.001) and effective refractory period (from 141.3 ± 4.8 to 175.6 ± 3.7 ms, P < 0.001) whilst increasing the maximal slope of restitution (apex, from 0.79 ± 0.09 to 1.57 ± 0.16, P < 0.001; and base, from 0.71 ± 0.06 to 1.44 ± 0.24, P < 0.001) and ventricular fibrillation threshold (from 5.3 ± 1.1 to 17.0 ± 2.9 mA, P < 0.001). In other hearts, blebbistatin significantly prolonged optically recorded action potentials (from 136.5 ± 6.3 to 173.0 ± 7.9 ms, P < 0.05, n= 4). In control experiments, the increase of MAPD with blebbistatin was present whether the hearts were perfused in constant-pressure mode (n= 5) or in unloaded conditions (n= 5). These data show that blebbistatin significantly affects cardiac electrophysiology. Its use in optical mapping studies should be treated with caution.
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Affiliation(s)
- Kieran E Brack
- Department of Cardiovascular Sciences, Cardiology group, University of Leicester, and Leicester NIHR Biomedical Research Unit in Cardiovascular Disease,Clinical Sciences Wing, Glenfield Hospital, Leicester LE3 9QP, UK
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