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Zhang L, Guo F, Xu S, Deng Q, Xie M, Sun J, Kwok RTK, Lam JWY, Deng H, Jiang H, Yu L, Tang BZ. AIEgen-Based Covalent Organic Frameworks for Preventing Malignant Ventricular Arrhythmias Via Local Hyperthermia Therapy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2304620. [PMID: 37532257 DOI: 10.1002/adma.202304620] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/14/2023] [Indexed: 08/04/2023]
Abstract
The engineering of aggregation-induced emission luminogens (AIEgen) based covalent organic frameworks (COFs), TDTA-COF, BTDTA-COF, and BTDBETA-COF are reported, as hyperthermia agents for inhibiting the occurrence of malignant ventricular arrhythmias (VAs). These AIE COFs exhibit dual functionality, as they not only directly modulate the function and neural activity of stellate ganglion (SG) through local hyperthermia therapy (LHT) but also induce the browning of white fat and improve the neuroinflammation peri-SG microenvironment, which is favorable for inhibiting ischemia-induced VAs. In vivo studies have confirmed that BTDBETA-COF-mediated LHT enhances thermogenesis and browning-related gene expression, thereby serving a synergistic role in combating VAs. Transcriptome analysis of peri-SG adipose tissue reveals a substantial downregulation of inflammatory cytokines, highlighting the potency of BTDBETA-COF-mediated LHT in ameliorating the neuroinflammation peri-SG microenvironment and offering myocardial and arrhythmia protection. The work on AIE COF-based hyperthermia agent for VAs inhibition provides a new avenue for mitigating cardiac sympathetic nerve hyperactivity.
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Affiliation(s)
- Liang Zhang
- Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
- Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Key Laboratory of Biomedical Polymers-Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Luojiashan, Wuhan, 430072, China
| | - Fuding Guo
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Saiting Xu
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Qiang Deng
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Mengjie Xie
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Jianwei Sun
- Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Ryan T K Kwok
- Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Jacky W Y Lam
- Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
| | - Hexiang Deng
- Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Key Laboratory of Biomedical Polymers-Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Luojiashan, Wuhan, 430072, China
| | - Hong Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Lilei Yu
- Department of Cardiology, Renmin Hospital of Wuhan University, Institute of Molecular Medicine, Renmin Hospital of Wuhan University, Hubei Key Laboratory of Autonomic Nervous System Modulation, Hubei Key Laboratory of Cardiology, Cardiovascular Research Institute, Wuhan University, Cardiac Autonomic Nervous System Research Center of Wuhan University, Taikang Center for Life and Medical Sciences, Wuhan University, Wuhan University, Jiefang Road, Wuhan, 430060, China
| | - Ben Zhong Tang
- Department of Chemistry and The Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, China
- Shenzhen Institute of Aggregate Science and Technology, School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
- Center for Aggregation-Induced Emission, South China University of Technology, Guangzhou, 510640, China
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Saitoh O, Watanabe J, Sugai A, Oikawa A, Sugai M, Chinushi M. Bepridil Inhibits Premature Ventricular Complexes Induced by Cardio-Sympathetic Nerve Stimulation in a Canine Experimental Model. Int Heart J 2020; 61:338-346. [PMID: 32173709 DOI: 10.1536/ihj.19-494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sympathetic nerve activity has arrhythmogenic potential for ventricular arrhythmias associated with structural heart diseases. However, a sufficient amount of beta-blockers occasionally cannot be prescribed in some patients.An experimental study was performed to clarify the therapeutic effects of bepridil, a multiple ionic current inhibitor that does not affect beta-adrenergic receptors, for premature beats occurring during enhanced sympathetic nerve activity. Cardio-sympathetic nerve activity was augmented via stellate-ganglion (SG) stimulation in a canine model (n = 8), and the arrhythmogenic potential and anti-arrhythmic effects of bepridil (2 and 4 mg/kg intravenously) were assessed. For safe use, vagal-stimulation-induced slow HR and programmed electrical stimulation were applied to evaluate possible pro-arrhythmic effects of the drug. Heart rate variability (HRV) indexes were used to estimate cardio-autonomic nerve activity.Either side of the SG-stimulation increased BP and HR. Premature beats were induced in 10/16 SG-stimulations and it was more frequent in left (8/8) rather than right stimulation (2/8). Following 2 mg/kg drug administration, premature beats were still inducible in 8/16 stimulations (7/8 in left and 1/8 in right), but burden of the premature beats decreased from 87.1 ± 46.8 to 62.1 ± 42.6 beats. After 4 mg/kg administration, premature beats were inducible in one SG-stimulation. Proarrhythmic effects were not observed in all experiments. Steady-state HRV indexes and percent increases in SG-stimulation-induced BP-elevation and HR-acceleration were similar among the 3 periods (before, 2 and 4 mg/kg of the drug).Bepridil may be an option for ventricular arrhythmias developed during enhanced cardio-sympathetic nerve activity with minimal effect on autonomic nerve responses.
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Affiliation(s)
- Osamu Saitoh
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
| | - Junya Watanabe
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
| | - Ayari Sugai
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
| | - Ayaka Oikawa
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
| | - Mika Sugai
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
| | - Masaomi Chinushi
- Cardiovascular Research, Graduate School of Health Sciences, Niigata University School of Medicine
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Hancox JC, Whittaker DG, Zhang H, Stuart AG. Learning from studying very rare cardiac conditions: the example of short QT syndrome. JOURNAL OF CONGENITAL CARDIOLOGY 2019. [DOI: 10.1186/s40949-019-0024-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Takasugi N, Takasugi M, Goto H, Kuwahara T, Nakashima T, Kubota T, Kanamori H, Kawasaki M, Nishigaki K, Minatoguchi S, Verrier RL. Significance of T-wave inversion triggered by spontaneous atrial premature beats in patients with long QT syndrome. Heart Rhythm 2018; 15:860-869. [DOI: 10.1016/j.hrthm.2018.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Indexed: 01/12/2023]
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Chang MG, de Lange E, Calmettes G, Garfinkel A, Qu Z, Weiss JN. Pro- and antiarrhythmic effects of ATP-sensitive potassium current activation on reentry during early afterdepolarization-mediated arrhythmias. Heart Rhythm 2013; 10:575-82. [PMID: 23246594 PMCID: PMC4285341 DOI: 10.1016/j.hrthm.2012.12.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Under conditions promoting early afterdepolarizations (EADs), ventricular tissue can become bi-excitable, that is, capable of wave propagation mediated by either the Na current (INa) or the L-type calcium current (ICa,L), raising the possibility that ICa,L-mediated reentry may contribute to polymorphic ventricular tachycardia (PVT) and torsades de pointes. ATP-sensitive K current (IKATP) activation suppresses EADs, but the effects on ICa,L-mediated reentry are unknown. OBJECTIVE To investigate the effects of IKATP activation on ICa,L-mediated reentry. METHODS We performed optical voltage mapping in cultured neonatal rat ventricular myocyte monolayers exposed to BayK8644 and isoproterenol. The effects of pharmacologically activating IKATP with pinacidil were analyzed. RESULTS In 13 monolayers with anatomic ICa,L-mediated reentry around a central obstacle, pinacidil (50 μM) converted ICa,L-mediated reentry to INa-mediated reentry. In 33 monolayers with functional ICa,L-mediated reentry (spiral waves), pinacidil terminated reentry in 17, converted reentry into more complex INa-mediated reentry resembling fibrillation in 12, and had no effect in 4. In simulated 2-dimensional bi-excitable tissue in which ICa,L- and INa-mediated wave fronts coexisted, slow IKATP activation (over minutes) reliably terminated rotors but rapid IKATP activation (over seconds) often converted ICa,L-mediated reentry to INa-mediated reentry resembling fibrillation. CONCLUSIONS IKATP activation can have proarrhythmic effects on EAD-mediated arrhythmias if ICa,L-mediated reentry is present.
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Affiliation(s)
- Marvin G. Chang
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Enno de Lange
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Guillaume Calmettes
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Alan Garfinkel
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
- Department of Integrative Biology and Physiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
- Department of Physiology, David Geffen School of Medicine at University of California, Los Angeles, California
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Izumi D, Chinushi M, Iijima K, Furushima H, Hosaka Y, Hasegawa K, Aizawa Y. The peak-to-end of the T wave in the limb ECG leads reflects total spatial rather than transmural dispersion of ventricular repolarization in an anthopleurin-A model of prolonged QT interval. Heart Rhythm 2012; 9:796-803. [DOI: 10.1016/j.hrthm.2011.11.046] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Indexed: 11/29/2022]
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Izumi D, Chinushi M, Iijima K, Ahara S, Komura S, Furushima H, Hosaka Y, Sanada A, Yagihara N, Aizawa Y. Effects of bepridil versus E-4031 on transmural ventricular repolarization and inducibility of ventricular tachyarrhythmias in the dog. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2010; 33:950-9. [PMID: 20487341 DOI: 10.1111/j.1540-8159.2010.02768.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Bepridil (a multiple channel blocker) may markedly prolong the QT interval and induce polymorphic ventricular tachyarrhythmias (VTA). We compared the transmural ventricular repolarization characteristics and inducibility of polymorphic VTA after administration of bepridil versus the pure I(Kr) blocker, E-4031, each administered to five open-chest dogs. METHODS We used plunge needle electrode to record transmural left ventricular (LV) repolarization and activation-recovery interval (ARI) to estimate local repolarization. The correlation between paced cycle length and ARI was separately examined in the LV endocardium, mid-myocardium (Mid), and epicardium. Attempts to induce VTA were made during bradycardia and sympathetic stimulation. RESULTS Bepridil and E-4031 prolonged QT interval and ARI in all LV layers, though the magnitude of prolongation was greatest in Mid, increasing the transmural ARI dispersion, particularly during bradycardia. Compared with E-4031, bepridil caused mild, reverse use-dependent changes in ventricular repolarization, and less ARI dispersion than E-4031 during slow ventricular pacing. Both drugs increased ARI(max) and cycle length at 50% of ARI(max), though the changes were smaller after bepridil than after E-4031 administration. Bradycardia after the administration of each drug induced no VTA; however, sympathetic stimulation induced sustained polymorphic VTA in two of five dogs treated with E-4031 versus no dog treated with bepridil. CONCLUSIONS Unlike the pure I(kr) blocker, E-4031, bepridil exhibited weak properties of reverse use-dependency and protected against sympathetic stimulation-induced VTA. It may be an effective supplemental treatment for recipients of implantable cardioverter defibrillator.
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Affiliation(s)
- Daisuke Izumi
- First Department of Internal Medicine, Niigata University School of Medicine, Niigata, Japan
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Kijtawornrat A, Panyasing Y, del Rio C, Hamlin RL. Assessment of ECG interval and restitution parameters in the canine model of short QT syndrome. J Pharmacol Toxicol Methods 2010; 61:231-7. [DOI: 10.1016/j.vascn.2010.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 02/01/2010] [Indexed: 11/17/2022]
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Hothi SS, Thomas G, Killeen MJ, Grace AA, Huang CLH. Empirical correlation of triggered activity and spatial and temporal re-entrant substrates with arrhythmogenicity in a murine model for Jervell and Lange-Nielsen syndrome. Pflugers Arch 2009; 458:819-35. [PMID: 19430811 PMCID: PMC2719739 DOI: 10.1007/s00424-009-0671-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Accepted: 04/07/2009] [Indexed: 11/23/2022]
Abstract
KCNE1 encodes the β-subunit of the slow component of the delayed rectifier K+ current. The Jervell and Lange-Nielsen syndrome is characterized by sensorineural deafness, prolonged QT intervals, and ventricular arrhythmogenicity. Loss-of-function mutations in KCNE1 are implicated in the JLN2 subtype. We recorded left ventricular epicardial and endocardial monophasic action potentials (MAPs) in intact, Langendorff-perfused mouse hearts. KCNE1−/− but not wild-type (WT) hearts showed not only triggered activity and spontaneous ventricular tachycardia (VT), but also VT provoked by programmed electrical stimulation. The presence or absence of VT was related to the following set of criteria for re-entrant excitation for the first time in KCNE1−/− hearts: Quantification of APD90, the MAP duration at 90% repolarization, demonstrated alterations in (1) the difference, ∆APD90, between endocardial and epicardial APD90 and (2) critical intervals for local re-excitation, given by differences between APD90 and ventricular effective refractory period, reflecting spatial re-entrant substrate. Temporal re-entrant substrate was reflected in (3) increased APD90 alternans, through a range of pacing rates, and (4) steeper epicardial and endocardial APD90 restitution curves determined with a dynamic pacing protocol. (5) Nicorandil (20 µM) rescued spontaneous and provoked arrhythmogenic phenomena in KCNE1−/− hearts. WTs remained nonarrhythmogenic. Nicorandil correspondingly restored parameters representing re-entrant criteria in KCNE1−/− hearts toward values found in untreated WTs. It shifted such values in WT hearts in similar directions. Together, these findings directly implicate triggered electrical activity and spatial and temporal re-entrant mechanisms in the arrhythmogenesis observed in KCNE1−/− hearts.
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Affiliation(s)
- Sandeep S Hothi
- Physiological Laboratory, Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
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Hothi SS, Booth SW, Sabir IN, Killeen MJ, Simpson F, Zhang Y, Grace AA, Huang CLH. Arrhythmogenic substrate and its modification by nicorandil in a murine model of long QT type 3 syndrome. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:267-80. [DOI: 10.1016/j.pbiomolbio.2009.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sabir IN, Fraser JA, Cass TR, Grace AA, Huang CLH. A quantitative analysis of the effect of cycle length on arrhythmogenicity in hypokalaemic Langendorff-perfused murine hearts. Pflugers Arch 2007; 454:925-36. [PMID: 17437126 PMCID: PMC2627988 DOI: 10.1007/s00424-007-0255-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Accepted: 03/13/2007] [Indexed: 11/09/2022]
Abstract
The clinically established proarrhythmic effect of bradycardia and antiarrhythmic effect of lidocaine (10 μM) were reproduced in hypokalaemic (3.0 mM K+) Langendorff-perfused murine hearts paced over a range (80–180 ms) of baseline cycle lengths (BCLs). Action potential durations (at 90% repolarization, APD90s), transmural conduction times and ventricular effective refractory periods (VERPs) were then determined from monophasic action potential records obtained during a programmed electrical stimulation procedure in which extrasystolic stimuli were interposed following regular stimuli at successively decreasing coupling intervals. A novel graphical analysis of epicardial and endocardial, local and transmural relationships between APD90, corrected for transmural conduction time where appropriate, and VERP yielded predictions in precise agreement with the arrhythmogenic findings obtained over the entire range of BCLs studied. Thus, in normokalaemic (5.2 mM K+) hearts a statistical analysis confirmed that all four relationships were described by straight lines of gradients not significantly (P > 0.05) different from unity that passed through the origin and thus subtended constant critical angles, θ with the abscissa (45.8° ± 0.9°, 46.6° ± 0.5°, 47.6° ± 0.5° and 44.9° ± 0.8°, respectively). Hypokalaemia shifted all points to the left of these reference lines, significantly (P < 0.05) increasing θ at BCLs of 80–120 ms where arrhythmic activity was not observed (∼63°, ∼54°, ∼55° and ∼58°, respectively) and further significantly (P < 0.05) increasing θ at BCLs of 140–180 ms where arrhythmic activity was observed (∼68°, ∼60°, ∼61° and ∼65°, respectively). In contrast, the antiarrhythmic effect of lidocaine treatment was accompanied by a significant (P < 0.05) disruption of this linear relationship and decreases in θ in both normokalaemic (∼40°, ∼33°, ∼39° and ∼41°, respectively) and hypokalaemic (∼40°, ∼44°, ∼50° and ∼48°, respectively) hearts. This extended a previous approach that had correlated alterations in transmural repolarization gradients with arrhythmogenicity in murine models of the congenital long QT syndrome type 3 and hypokalaemia at a single BCL. Thus, the analysis in terms of APD90 and VERP provided a more sensitive indication of the effect of lidocaine than one only considering transmural repolarization gradients and may be particularly applicable in physiological and pharmacological situations in which these parameters diverge.
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Affiliation(s)
- Ian N. Sabir
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
| | - James A. Fraser
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
| | - Thomas R. Cass
- Statistical Laboratory, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WB UK
| | - Andrew A. Grace
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
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Chinushi M, Sugiura H, Komura S, Hirono T, Izumi D, Tagawa M, Furushima H, Aizawa Y. Effects of Intravenous Magnesium in a Prolonged QT Interval Model of Polymorphic Ventricular Tachycardia Focus on Transmural Ventricular Repolarization. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:844-50. [PMID: 16105013 DOI: 10.1111/j.1540-8159.2005.00178.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND This study was performed to clarify the antiarrhythmic effects of magnesium sulfate (Mg(++)) in a prolonged QT interval canine model of polymorphic ventricular tachyarrhythmia (VTA). METHODS In six experiments in a canine model of prolonged QT by anthopleurin-A, Mg(++) was administered in boluses of 0.2 mL/kg during repetitive episodes of self-terminating polymorphic VTA or frequent premature ventricular complexes (PVCs). The distribution of ventricular repolarization across the left ventricular(LV) wall and dispersion of transmural repolarization were analyzed before, and 30 and 120 seconds after Mg(++) administration, during ventricular pacing at 100 bpm. Transmural unipolar electrograms were recorded from multipolar needle electrodes, and local activation-recovery intervals (ARI) were measured. RESULTS Mg(++) rapidly eliminated self-terminating polymorphic VTA and all isolated PVCs. During ventricular pacing at 100 bpm, Mg(++) caused modest shortening of ARI at all recording sites. Since the magnitude of ARI shortening was greater at mid-myocardial sites than at other ventricular sites, mean transmural ARI dispersion decreased from 80 +/- 22 to 45 +/- 18 ms within 30 seconds after Mg(++) injection. However, this effect was transient, and, at 120 seconds after Mg(++) administration, ARI had increased all sites and transmural ARI dispersion lengthened to 65 +/- 18 ms. Besides suppression of triggered premature activity, homogenization of transmural ventricular repolarization was associated with the antiarrhythmic effects of intravenous Mg(++) in this model. CONCLUSION Since these effects were transient, a continuous intravenous infusion of Mg(++) is preferred to prevent recurrences of VTA.
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Affiliation(s)
- Masaomi Chinushi
- School of Health Science, Niigata University School of Medicine, Niigata, Japan.
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Shivkumar K, Valderrabano M. Use of potassium channel openers for pharmacologic modulation of cardiac excitability. J Cardiovasc Electrophysiol 2004; 15:821-3. [PMID: 15250870 DOI: 10.1046/j.1540-8167.2004.04324.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chinushi M, Tagawa M, Sugiura H, Komura S, Hosaka Y, Washizuka T, Aizawa Y. Ventricular tachyarrhythmias in a canine model of LQT3: arrhythmogenic effects of sympathetic activity and therapeutic effects of mexiletine. Circ J 2003; 67:263-8. [PMID: 12604879 DOI: 10.1253/circj.67.263] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ventricular tachyarrhythmias associated with the LQT3 syndrome are typically bradycardia-dependent. However, some episodes can be associated with exercise or emotional stress, suggesting a different arrhythmogenic mechanism when sympathetic activity predominates. This study examined the potential arrhythmogenic mechanisms during periods of autonomically mediated transient heart rate acceleration in a canine anthopleurin-A model of LQT3 syndrome. Using plunge needle electrodes, transmural unipolar electrograms of the left ventricle were recorded from endocardial (Endo), mid-myocardial (Mid) and epicardial (Epi) sites. The activation-recovery interval (ARI) was measured to estimate local refractoriness. The cardiac cycle length was gradually shortened by cessation of vagal stimulation (vagal stimulation protocol (VSP)), and intramural electrograms and onset mode of ventricular tachyarrhythmias were analyzed in 7 experiments. The VSP was performed 8 times before and 5 times after administration of mexiletine in each experiment. Before mexiletine, vagal stimulation slowed the heart rate and created large transmural ARI dispersion because of a greater ARI prolongation at Mid rather than Epi/Endo sites. After cessation of vagal stimulation, unipolar electrograms started to show ARI alternans and ventricular premature beats developed sporadically. Sustained ventricular tachyarrhythmias were induced in 12 of the 56 trials of the VSP. Initiation of ventricular tachyarrhythmias was associated with delayed conduction at Mid/Endo sites. Mexiletine attenuated transmural ARI dispersion, and neither ARI alternans nor ventricular tachyarrhythmias was observed during all 35 trials of the VSP after mexiletine administration. Heart rate acceleration induced by an abrupt shift to a state of predominant sympathetic activity enhances arrhythmias in this LQT3 model. Mexiletine homogenizes ventricular repolarization, suppresses premature complexes and was antiarrhythmic during ventricular tachyarrhythmias induced by the VSP.
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Affiliation(s)
- Masaomi Chinushi
- School of Health Science, Niigata University School of Medicine, Japan.
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Affiliation(s)
- P D Booker
- Cardiac Unit, Royal Liverpool Children's Hospital, Eaton Road, Liverpool L12 2AP, UK.
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