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Goto A, Kambayashi R, Izumi-Nakaseko H, Shinozaki M, Takei Y, Sugiyama A. Characterization of electropharmacological profile of an anti-atrial fibrillatory drug vernakalant along with potential risk toward torsade de pointes: Translational studies using isoflurane-anesthetized dogs and isolated rat aortic preparations. J Pharmacol Sci 2023; 152:201-209. [PMID: 37344055 DOI: 10.1016/j.jphs.2023.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/01/2023] [Accepted: 05/10/2023] [Indexed: 06/23/2023] Open
Abstract
We simultaneously assessed electropharmacological effects of anti-atrial fibrillatory drug vernakalant and its potential risk toward torsade de pointes. Vernakalant hydrochloride in doses of 0.3 and 3 mg/kg/10 min was intravenously administered to isoflurane-anesthetized beagle dogs without (n = 5) and with (n = 4) α-adrenoceptor blockade. Its vascular effect was analyzed using the rat aortae (n = 12). Vernakalant increased total peripheral vascular resistance and preload to left ventricle, leading to transient elevation of mean blood pressure indirectly via non-adrenergic pathway. Vernakalant suppressed sinus automaticity, ventricular contractility and intra-atrial/atrioventricular nodal/intraventricular conductions, and decreased cardiac output. Moreover, vernakalant prolonged atrial/ventricular effective refractory period by 53/55 ms, respectively, whereas it delayed ventricular repolarization in a reverse frequency-dependent manner. The extent of prolongation in early/late ventricular repolarization and electrically vulnerable period was 26/32 and 9 ms, respectively when QT-interval prolongation was the greatest. We compared them with those of known anti-atrial fibrillatory drugs; ranolazine, amiodarone, dronedarone, dl-sotalol and bepridil. The magnitude of vernakalant to alter those variables was the greater among those drugs except that the atrial selectivity was the lesser of those. Thus, vernakalant is expected to be efficacious against atrial fibrillation, but caution should be excised on its use for patients having labile ventricular function and repolarization.
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Affiliation(s)
- Ai Goto
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan
| | - Ryuichi Kambayashi
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan
| | - Hiroko Izumi-Nakaseko
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan
| | - Makoto Shinozaki
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan
| | - Yoshinori Takei
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan
| | - Atsushi Sugiyama
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo 143-8540, Japan.
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Chen M, Wang Z, Lai X, Wang S, Wu Z, Liu Q, Zhou S. Transient cardiac electrophysiological changes in a rat model of subarachnoid haemorrhage: a brain-heart interaction. Europace 2023; 25:euad171. [PMID: 37337928 PMCID: PMC10306271 DOI: 10.1093/europace/euad171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/15/2023] [Accepted: 05/17/2023] [Indexed: 06/21/2023] Open
Abstract
AIMS Subarachnoid haemorrhage (SAH) is one of the causes of sudden cardiac death (SCD). However, the time course of ventricular arrhythmias and potential mechanisms responsible for this effect after SAH remain unknown. OBJECTIVE This study aims to investigate the effect of SAH on ventricular electrophysiological changes and its potential mechanisms in long-term phase. METHODS AND RESULTS We examined the ventricular electrophysiological remodelling and potential mechanisms in a Sprague Dawley rat model of SAH at six time points (baseline, and Days 1, 3, 7, 14 and 28) and explored the potential mechanisms. We measured the ventricular effective refractory period (ERP), ventricular fibrillation threshold (VFT) and left stellate ganglion (LSG) activity at different time points before and after SAH. We also detected neuropeptide Y (NPY) levels in plasma and myocardial tissues by enzyme-linked immunosorbent assay, and quantified NPY 1 receptor (NPY1R) protein and mRNA expression levels by western blotting and quantitative real-time reverse transcription-polymerase chain reaction, respectively. Subarachnoid haemorrhage gradually prolonged QTc intervals, shortened ventricular ERP and reduced VFT during the acute phase, peaking at Day 3. However, no significant changes were observed from Days 14 to 28 compared to Day 0. Subarachnoid haemorrhage gradually increased LSG activity, increased NPY concentrations and up-regulated NPY1R expression in the acute phase of SAH, peaking at Day 3. However, no significant variations were found from Days 14 to 28 compared to Day 0. CONCLUSION Subarachnoid haemorrhage increases the transient susceptibility of VAs in the acute phase, and the underlying mechanisms for this response included increased sympathetic activity and up-regulated NPY1R expression.
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Affiliation(s)
- Mingxian Chen
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Renmin Road, Furong District, Changsha 410011, China
| | - Zhuo Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Xin Lai
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Songyun Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhihong Wu
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Renmin Road, Furong District, Changsha 410011, China
| | - Qiming Liu
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Renmin Road, Furong District, Changsha 410011, China
| | - Shenghua Zhou
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Renmin Road, Furong District, Changsha 410011, China
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Adachi T, Asakawa T, Yamauchi Y, Naito S, Yoshida K, Nakagawa K, Nakamura K, Yamasaki H, Sekiguchi Y, Nogami A, Suzuki F, Ieda M, Aonuma K. Dual atrioventricular nodal non-reentrant tachycardia: Various atrioventricular conduction responses to atrioventricular simultaneous pacing. Heart Rhythm 2022; 19:1841-1855. [PMID: 35817252 DOI: 10.1016/j.hrthm.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 06/30/2022] [Accepted: 07/02/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Specific pacing methods to unmask the existence of the dual atrioventricular (AV) nodal pathway in patients with dual AV nodal non-reentrant tachycardia remain to be established. OBJECTIVE This study aimed to determine the electrophysiological characteristics of dual AV nodal non-reentrant tachycardia by its responses to specific pacing methods. METHODS Five patients diagnosed as having dual AV nodal non-reentrant tachycardia were retrospectively investigated. RESULTS Atrial pacing could not induce the clinical tachycardia as continuous double firing in any of the 5 patients, but did induce sudden prolongation of the A-H interval as the linking phenomenon in 1 patient. A single atrial extrastimulation after sinus excitations was performed without interruption of double firing in 1 patient, and it induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals. The pacing method of AV simultaneous basic pacing preceding atrial programmed extrastimulation did not allow interruptions of double firing during the basic drive trains and induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals in all 5 patients, even in 1 patient without inducibility of the clinical tachycardia in the catheterization laboratory. The double ventricular response phenomenon within the limited range of the extrastimulus intervals may be based on the existence of the dual AV nodal pathway with concealed retrograde penetration. CONCLUSION The AV simultaneous basic pacing preceding atrial programmed extrastimulation method consistently and reproducibly unmasked the existence of the dual AV nodal pathway as the double ventricular response phenomenon in patients with dual AV nodal non-reentrant tachycardia.
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Affiliation(s)
- Toru Adachi
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
| | - Tetsuya Asakawa
- Department of Cardiology, Yamanashi Kosei Hospital, Yamanashi, Japan
| | - Yasuteru Yamauchi
- Department of Cardiology, Yokohama City Minato Red Cross Hospital, Yokohama, Japan
| | - Shigeto Naito
- Division of Cardiology, Gunma Prefectural Cardiovascular Center, Maebashi, Japan
| | - Kentaro Yoshida
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Kazuya Nakagawa
- Department of Cardiology, Yamanashi Kosei Hospital, Yamanashi, Japan
| | - Kohki Nakamura
- Division of Cardiology, Gunma Prefectural Cardiovascular Center, Maebashi, Japan
| | - Hiro Yamasaki
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Yukio Sekiguchi
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Akihiko Nogami
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Fumio Suzuki
- Department of Cardiology, Fukujuji Hospital, Tokyo, Japan
| | - Masaki Ieda
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Kazutaka Aonuma
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
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Iwasaki YK, Sekiguchi A, Kato T, Yamashita T. Glucocorticoid Induces Atrial Arrhythmogenesis via Modification of Ion Channel Gene Expression in Rats. Int Heart J 2022; 63:375-383. [PMID: 35354756 DOI: 10.1536/ihj.21-677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Excess psychological stress is one of the precipitating factors for paroxysmal atrial fibrillation (AF), although the involved mechanisms are still uncertain. To test a hypothesis that one of the stress-induced hormones, glucocorticoid, is involved in the pathogenesis of stress-induced AF, we investigated whether the glucocorticoid could alter the temporal profile of cardiac ion channels gene expression, thereby leading to atrial arrhythmogenesis.Dexamethasone (DEX, 1.0 mg/kg) was injected subcutaneously in Sprague-Dawley rats. At predetermined times after DEX injection (0, 1, 3, 6, 12, and 24 hours), the mRNA levels of cardiac ion channel genes (erg, KvLQT1, Kv4.3, Kv4.2, Kv2.1, Kv1.5, Kv1.4, Kv1.2, SUR2A, Kir6.2, Kir3.4, Kir3.1 Kir2.2, Kir2.1, SCN5A, and α1C) were determined using RNase protection assay. DEX induced immediate and transient increase in the mRNA level of Kv1.5 and Kir2.2 with peaks at 6 (5.0 fold) and 3 hours (3.3 fold) after DEX injection, respectively. Patch-clamp studies revealed a significantly increased current density of the corresponding current, IKur and IK1 at 6 hours after DEX injection. Simultaneously, electrophysiological study in isolated perfused hearts showed significantly increased number of repetitive atrial responses induced by single atrial extrastimulus (3.2 ± 2.4 to 26.7 ± 16.4, P = 0.004) with shorting of the refractory period (36.4 ± 4.6 to 27.4 ± 5.5 ms, P = 0.049) after DEX injection.Glucocorticoid immediately modified Kv1.5 and Kir2.2 gene expression at pretranslational levels, thus leading to effective refractory period shortening that could be arrhythmogenic. These results implied that transient glucocorticoid-induced biochemical modification of cardiac ion channels might be one of the mechanisms underlying the stress-induced paroxysmal AF.
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Affiliation(s)
- Yu-Ki Iwasaki
- Department of Cardiovascular Medicine, Nippon Medical School
| | | | - Takeshi Kato
- Department of Cardiovascular Medicine, Graduate School of Medical Science, Kanazawa University
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Unger LA, Azzolin L, Nothstein M, Sánchez J, Luik A, Seemann G, Yeshwant S, Oesterlein T, Dössel O, Schmitt C, Spector P, Loewe A. Cycle length statistics during human atrial fibrillation reveal refractory properties of the underlying substrate: a combined in silico and clinical test of concept study. Europace 2021; 23:i133-i142. [PMID: 33751084 DOI: 10.1093/europace/euaa404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 11/12/2022] Open
Abstract
AIMS The treatment of atrial fibrillation beyond pulmonary vein isolation has remained an unsolved challenge. Targeting regions identified by different substrate mapping approaches for ablation resulted in ambiguous outcomes. With the effective refractory period being a fundamental prerequisite for the maintenance of fibrillatory conduction, this study aims at estimating the effective refractory period with clinically available measurements. METHODS AND RESULTS A set of 240 simulations in a spherical model of the left atrium with varying model initialization, combination of cellular refractory properties, and size of a region of lowered effective refractory period was implemented to analyse the capabilities and limitations of cycle length mapping. The minimum observed cycle length and the 25% quantile were compared to the underlying effective refractory period. The density of phase singularities was used as a measure for the complexity of the excitation pattern. Finally, we employed the method in a clinical test of concept including five patients. Areas of lowered effective refractory period could be distinguished from their surroundings in simulated scenarios with successfully induced multi-wavelet re-entry. Larger areas and higher gradients in effective refractory period as well as complex activation patterns favour the method. The 25% quantile of cycle lengths in patients with persistent atrial fibrillation was found to range from 85 to 190 ms. CONCLUSION Cycle length mapping is capable of highlighting regions of pathologic refractory properties. In combination with complementary substrate mapping approaches, the method fosters confidence to enhance the treatment of atrial fibrillation beyond pulmonary vein isolation particularly in patients with complex activation patterns.
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Affiliation(s)
- Laura A Unger
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Luca Azzolin
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Mark Nothstein
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Jorge Sánchez
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Armin Luik
- Medizinische Klinik IV, Städtisches Klinikum Karlsruhe, Karlsruhe 76133, Germany
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg Bad Krozingen, Medical Center, University of Freiburg, Freiburg 79110, Germany.,Faculty of Medicine, University of Freiburg, Freiburg 79110, Germany
| | - Srinath Yeshwant
- Division of Cardiovascular Medicine, College of Medicine, University of Vermont, Burlington, Colchester, VT 05446, USA
| | - Tobias Oesterlein
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Olaf Dössel
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Claus Schmitt
- Medizinische Klinik IV, Städtisches Klinikum Karlsruhe, Karlsruhe 76133, Germany
| | - Peter Spector
- Division of Cardiovascular Medicine, College of Medicine, University of Vermont, Burlington, Colchester, VT 05446, USA
| | - Axel Loewe
- Department of Electrical Engineering and Information Technology, Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
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Obergassel J, O'Reilly M, Sommerfeld LC, Kabir SN, O'Shea C, Syeda F, Eckardt L, Kirchhof P, Fabritz L. Effects of genetic background, sex, and age on murine atrial electrophysiology. Europace 2021; 23:958-969. [PMID: 33462602 DOI: 10.1093/europace/euaa369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Indexed: 11/14/2022] Open
Abstract
AIMS Genetically altered mice are powerful models to investigate mechanisms of atrial arrhythmias, but normal ranges for murine atrial electrophysiology have not been robustly characterized. METHODS AND RESULTS We analyzed results from 221 electrophysiological (EP) studies in isolated, Langendorff-perfused hearts of wildtype mice (114 female, 107 male) from 2.5 to 17.7 months (mean 7 months) with different genetic backgrounds (C57BL/6, FVB/N, MF1, 129/Sv, Swiss agouti). Left atrial monophasic action potential duration (LA-APD), interatrial activation time (IA-AT), and atrial effective refractory period (ERP) were summarized at different pacing cycle lengths (PCLs). Factors influencing atrial electrophysiology including genetic background, sex, and age were determined. LA-APD70 was 18 ± 0.5 ms, atrial ERP was 27 ± 0.8 ms, and IA-AT was 17 ± 0.5 ms at 100 ms PCL. LA-APD was longer with longer PCL (+17% from 80 to 120 ms PCL for APD70), while IA-AT decreased (-7% from 80 to 120 ms PCL). Female sex was associated with longer ERP (+14% vs. males). Genetic background influenced atrial electrophysiology: LA-APD70 (-20% vs. average) and atrial ERP (-25% vs. average) were shorter in Swiss agouti background compared to others. LA-APD70 (+25% vs. average) and IA-AT (+44% vs. average) were longer in 129/Sv mice. Atrial ERP was longer in FVB/N (+34% vs. average) and in younger experimental groups below 6 months of age. CONCLUSION This work defines normal ranges for murine atrial EP parameters. Genetic background has a profound effect on these parameters, at least of the magnitude as those of sex and age. These results can inform the experimental design and interpretation of murine atrial electrophysiology.
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Affiliation(s)
- Julius Obergassel
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Molly O'Reilly
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Laura C Sommerfeld
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - S Nashitha Kabir
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Fahima Syeda
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Lars Eckardt
- Department of Cardiology II - Electrophysiology, University Hospital Münster, Münster, Germany
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology, UHB NHS Trust, Birmingham, UK.,Department of Cardiology, SWBH NHS Trust, Birmingham City Hospital, Birmingham, UK.,German Center for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,University Heart and Vascular Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology, UHB NHS Trust, Birmingham, UK
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Liang Y, Wang N, Yu H, Xu B, Yan X, Wu M, Gao Y, Liu R, Xu G, Li Z, He J, Wang Z, Han Y. A simple and practical criterion for determining a failed His-bundle pacing. Europace 2021; 22:ii61-ii66. [PMID: 33083840 DOI: 10.1093/europace/euaa244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/28/2020] [Indexed: 11/14/2022] Open
Abstract
AIMS To establish a simple criterion for determining a failed His-bundle pacing (HBP). This criterion states that if stimulus to QRS end interval is longer than His-bundle potential to QRS end interval ('S-QRSend > H-QRSend') then a failed HBP can be determined. METHODS AND RESULTS We performed retrospective analysis on 737 pacing tests around His-bundle in 241 patients and prospective analysis on 400 tests in 123 patients. A successful HBP is defined as that whole His-bundle is captured with or without capture of adjacent ventricular myocardium, otherwise, a failed HBP was considered. The output criteria and effective refractory period criteria were used as the gold standards for determining a successful HBP. The gold standards are that if decreasing the pacing output or pacing cycle length to a certain level results in duration or morphology changes of QRS, then a successful HBP is ascertained. In retrospective analysis of patients with normal His-Purkinje conduction, a failed HBP was determined in 31% (154/492) of pacing tests according to 'S-QRSend > H-QRSend'; all of them were validated by the gold standards (specificity = 100%). In prospective study, a failed HBP was confirmed according to the simple criterion with 100% accuracy in 33% (79/241) pacing tests. This simple criterion was also suitable for patients with His-Purkinje conduction disease although cases with 'S-QRSend > H-QRSend' rarely occurred. CONCLUSION A failed HBP can be easily and reliably determined solely by 'S-QRSend > H-QRSend' in more than 30% pacing tests.
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Affiliation(s)
- Yanchun Liang
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Na Wang
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Haibo Yu
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Baige Xu
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Xiaolei Yan
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Min Wu
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Yang Gao
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Rong Liu
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Guoqing Xu
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Zhenhui Li
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Jiaqi He
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Zulu Wang
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
| | - Yaling Han
- Department of Cardiology, General Hospital of Northern Theater Command, Shenyang 110016, People's Republic of China
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Hassan H, Greco LV, Meshoyrer DI, Li Y, Zhang Y, Cohen TJ. Novel beta-blocker pretreatment prevents alcohol-induced atrial fibrillation in a rat model. Heart Rhythm O2 2020; 1:120-125. [PMID: 34113866 PMCID: PMC8183851 DOI: 10.1016/j.hroo.2020.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background A case report published in 2019 described a patient who presented with difficult-to-manage atrial fibrillation (AF) that consistently was associated with alcohol consumption. After the patient did not respond to drug therapy, a novel beta-blocker (BB) pretreatment regimen initiated immediately before alcohol consumption successfully prevented AF occurrence. Objective The purpose of this study was to test the hypothesis that a novel prophylactic BB therapy given before alcohol consumption could prevent AF in a rat model. Methods An alcohol-induced AF model was developed in adult Sprague-Dawley rats of both sexes by administering alcohol (2 g/kg intraperitoneal [IP]) once every other day for a total of 4 times. Three groups were enrolled: alcohol (EtOH; n = 10); alcohol plus BB (metoprolol 50 mg/kg IP) pretreatment (EtOH+BB; n = 10); and control (n = 9). Cardiac function (assessed by echocardiography and left ventricular hemodynamics) and in vivo atrial electrophysiology and AF inducibility tests were performed 24 hours after the last injection. Results All but 1 rat completed the study. Alcohol exposure did not significantly impact cardiac function and the atrial effective refractory period. However, alcohol exposure significantly increased AF inducibility [median (first and third quartile [Q1–Q3]) 0% (0%–0%) in control vs 60% (25%–100%) in the EtOH group; P <.05] and AF duration [0 second (0–0 second) in control vs 0.81 second (0.24–3.67 seconds) in the EtOH group; P <.05]. Compared to the EtOH group, the EtOH+BB group had significantly reduced AF inducibility [0% (0%–22.5%); P <.05] and duration [0 second (0–0.2 second); P <.05]. Conclusion Metoprolol pretreatment before alcohol administration significantly decreased AF induction in rats. These findings suggest that BB pretreatment is a promising prophylaxis regimen for alcohol-induced AF.
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Affiliation(s)
- Hebah Hassan
- Department of Clinical Specialties, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Lisa V Greco
- Department of Clinical Specialties, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Daniel I Meshoyrer
- Department of Clinical Specialties, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Ying Li
- Department of Clinical Specialties, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Youhua Zhang
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
| | - Todd J Cohen
- Department of Clinical Specialties, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York
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9
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Ding WG, Tano A, Mi X, Kojima A, Seto T, Matsuura H. Identification of Verapamil Binding Sites Within Human Kv1.5 Channel Using Mutagenesis and Docking Simulation. Cell Physiol Biochem 2019; 52:302-314. [PMID: 30816676 DOI: 10.33594/000000022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 01/10/2019] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS The phenylalkylamine class of L-type Ca2+ channel antagonist verapamil prolongs the effective refractory period (ERP) of human atrium, which appears to contribute to the efficacy of verapamil in preventing reentrant-based atrial arrhythmias including atrial fibrillation. This study was designed to investigate the molecular and electrophysiological mechanism underlying the action of verapamil on human Kv1.5 (hKv1.5) channel that determines action potential duration and ERP in human atrium. METHODS Site-directed mutagenesis created 10 single-point mutations within pore region of hKv1.5 channel. Wholecell patch-clamp method investigated the effect of verapamil on wild-type and mutant hKv1.5 channels heterologously expressed in Chinese hamster ovary cells. Docking simulation was conducted using open-state homology model of hKv1.5 channel pore. RESULTS Verapamil preferentially blocked hKv1.5 channel in its open state with IC50 of 2.4±0.6 μM (n = 6). The blocking effect of verapamil was significantly attenuated in T479A, T480A, I502A, V505A, I508A, L510A, V512A and V516A mutants, compared with wild-type hKv1.5 channel. Computer docking simulation predicted that verapamil is positioned within central cavity of channel pore and has contact with Thr479, Thr480, Val505, Ile508, Ala509, Val512, Pro513 and Val516. CONCLUSION Verapamil acts as an open-channel blocker of hKv1.5 channel, presumably due to direct binding to specific amino acids within pore region of hKv1.5 channel, such as Thr479, Thr480, Val505, Ile508, Val512 and Val516. This blocking effect of verapamil on hKv1.5 channel appears to contribute at least partly to prolongation of atrial ERP and resultant antiarrhythmic action on atrial fibrillation in humans.
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Affiliation(s)
- Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Ayami Tano
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Xinya Mi
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Japan
| | - Tomoyoshi Seto
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan,
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10
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Goto A, Nakamura Y, Lubna NJ, Chiba K, Hagiwara-Nagasawa M, Izumi-Nakaseko H, Ando K, Naito AT, Sugiyama A. Analysis of Safety Margin of Lithium Carbonate Against Cardiovascular Adverse Events Assessed in the Halothane-Anesthetized Dogs. Cardiovasc Toxicol 2018; 18:530-536. [PMID: 29845450 DOI: 10.1007/s12012-018-9464-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Lithium is one of the classical drugs that have been widely used for treating bipolar disorder. However, several cardiac side effects including sick sinus syndrome, bundle branch block, ventricular tachycardia/fibrillation, non-specific T-wave abnormalities in addition to Brugada-type electrocardiographic changes have been noticed in patients who were given antidepressant, anticonvulsant, and/or antipsychotic drugs besides lithium. In this study, we assessed cardiohemodynamic and electrophysiological effects of lithium carbonate by itself to begin to analyze onset mechanisms of its cardiovascular side effects. Lithium carbonate in intravenous doses of 0.1, 1, and 10 mg/kg over 10 min was cumulatively administered with an interval of 20 min to the halothane-anesthetized beagle dogs (n = 4), which provided peak plasma Li+ concentrations of 0.02, 0.18, and 1.79 mEq/L, respectively, reflecting sub-therapeutic to toxic concentrations. The low and middle doses prolonged the ventricular effective refractory period at 30 min and for 5-30 min, respectively. The high dose decreased the heart rate for 45-60 min, delayed the intraventricular conduction for 15-20 min and the ventricular repolarization at 45 min, and prolonged the effective refractory period for 5-60 min. No significant change was detected in the other cardiovascular variables. Thus, lithium alone may have a wide safety margin against hemodynamic adverse events; however, it would directly and/or indirectly inhibit Na+ and K+ channels, which may synergistically increase the ventricular refractoriness from the sub-therapeutic concentration and decrease the heart rate at the supra-therapeutic one. These findings may partly explain its clinically observed various types of arrhythmias as well as electrocardiographic changes.
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Affiliation(s)
- Ai Goto
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Yuji Nakamura
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Nur Jaharat Lubna
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Koki Chiba
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Mihoko Hagiwara-Nagasawa
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Hiroko Izumi-Nakaseko
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Kentaro Ando
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Atsuhiko T Naito
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan
| | - Atsushi Sugiyama
- Department of Pharmacology, Toho University Graduate School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
- Department of Pharmacology, Faculty of Medicine, Toho University, 5-21-16 Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
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11
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Osadchii OE. Assessments of the QT/QRS restitution in perfused guinea-pig heart can discriminate safe and arrhythmogenic drugs. J Pharmacol Toxicol Methods 2017; 87:27-37. [PMID: 28552278 DOI: 10.1016/j.vascn.2017.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/25/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Drug-induced arrhythmia remains a matter of serious clinical concern, partly due to low prognostic value of currently available arrhythmic biomarkers. METHODS This study examined whether arrhythmogenic risks can be predicted through assessments of the rate adaptation of QT interval, ventricular effective refractory period (ERP), or the QT/QRS ratio, in perfused guinea-pig hearts. RESULTS When the maximum restitution slope was taken as a metric of proarrhythmia, neither QT interval nor ERP measurements at progressively increased pacing rates were found to fully discriminate arrhythmogenic drugs (dofetilide, quinidine, flecainide, and procainamide) from those recognized as safe antiarrhythmics (lidocaine and mexiletine). For example, the slope of QT restitution was increased by dofetilide and quinidine, but remained unchanged by flecainide, procainamide, lidocaine, and mexiletine. With ERP rate adaptation, even though the restitution slope was increased by dofetilide, all class I agents reduced the slope value independently of their safety profile. The QRS measurements revealed variable drug effects, ranging from significant use-dependent conduction slowing (flecainide, quinidine, and procainamide) to only modest increase in QRS (lidocaine and mexiletine), or no change at all (dofetilide). However, with the QT/QRS rate adaptation, the restitution slope was significantly increased by all agents which have been reported to produce proarrhythmic effects (dofetilide, quinidine, flecainide, and procainamide), but not changed by lidocaine and mexiletine. DISCUSSION These findings suggest that the slope of the QT/QRS rate adaptation can be considered as a novel electrophysiological biomarker in predicting potential arrhythmic risks associated with pharmacotherapy in cardiac patients.
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Affiliation(s)
- Oleg E Osadchii
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark; Department of Health Science and Technology, University of Aalborg, Fredrik Bajers Vej 7E, 9220 Aalborg, Denmark.
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12
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Klein MG, Shou M, Stohlman J, Solhjoo S, Haigney M, Tidwell RR, Goldstein RE, Flagg TP, Haigney MC. Role of suppression of the inward rectifier current in terminal action potential repolarization in the failing heart. Heart Rhythm 2017; 14:1217-1223. [PMID: 28396172 DOI: 10.1016/j.hrthm.2017.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND The failing heart exhibits an increased arrhythmia susceptibility that is often attributed to action potential (AP) prolongation due to significant ion channel remodeling. The inwardly rectifying K+ current (IK1) has been reported to be reduced, but its contribution to shaping the AP waveform and cell excitability in the failing heart remains unclear. OBJECTIVE The purpose of this study was to define the effect of IK1 suppression on the cardiac AP and excitability in the normal and failing hearts. METHODS We used electrophysiological and pharmacological approaches to investigate IK1 function in a swine tachy-pacing model of heart failure (HF). RESULTS Terminal repolarization of the AP (TRAP; the time constant of the exponential fit to terminal repolarization) was markedly prolonged in both myocytes and arterially perfused wedges from animals with HF. TRAP was increased by 54.1% in HF myocytes (P < .001) and 26.2% in HF wedges (P = .014). The increase in TRAP was recapitulated by the potent and specific IK1 inhibitor, PA-6 (pentamidine analog 6), indicating that IK1 is the primary determinant of the final phase of repolarization. Moreover, we find that IK1 suppression reduced the ratio of effective refractory period to AP duration at 90% of repolarization, permitting re-excitation before full repolarization, reduction of AP upstroke velocity, and likely promotion of slow conduction. CONCLUSION Using an objective measure of terminal repolarization, we conclude that IK1 is the major determinant of the terminal repolarization time course. Moreover, suppression of IK1 prolongs repolarization and reduces postrepolarization refractoriness without marked effects on the overall AP duration. Collectively, these findings demonstrate how IK1 suppression may contribute to arrhythmogenesis in the failing heart.
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Affiliation(s)
- Michael G Klein
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
| | - Matie Shou
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Jayna Stohlman
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland
| | - Soroosh Solhjoo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Myles Haigney
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Richard R Tidwell
- Department of Pathology and Laboratory Medicine, School of Medicine, The University of North Carolina, Chapel Hill, North Carolina
| | - Robert E Goldstein
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Thomas P Flagg
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Mark C Haigney
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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13
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Chang Q, Liu R. Atrioventricular dissociation with QRS complex change in the atrioventricular block: What are the degree and the site of block? Int J Cardiol 2016; 225:215-217. [PMID: 27728867 DOI: 10.1016/j.ijcard.2016.09.096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/25/2016] [Indexed: 10/20/2022]
Affiliation(s)
- Qinghua Chang
- The Cardiovascular Institute of the First Affiliated Hospital of Jinzhou Medical University, China.
| | - Renguang Liu
- The Cardiovascular Institute of the First Affiliated Hospital of Jinzhou Medical University, China.
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14
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Yazaki K, Enta K, Kataoka S, Kahata M, Kumagai A, Inoue K, Koganei H, Otsuka M, Ishii Y. Interesting electrophysiological findings in a patient with coexistence of atrial tachycardia originating from coronary sinus and slow-fast atrioventricular nodal reentrant tachycardia. J Cardiol Cases 2016; 15:80-83. [PMID: 30279745 DOI: 10.1016/j.jccase.2016.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/19/2016] [Accepted: 10/24/2016] [Indexed: 10/20/2022] Open
Abstract
Slow-fast atrioventricular nodal tachycardia (AVNRT) has various electrophysiological aspects due to atrioventricular (AV) nodal physiology. In addition, concomitantly another form of arrhythmia with AVNRT, especially atrial tachycardia (AT), was an infrequent arrhythmia. A 38-year-old female with narrow QRS tachycardia underwent electrophysiological study due to frequent faintness. The electrophysiological study disclosed the coexistence of AT originating from coronary sinus (CS) with slow-fast AVNRT. We easily diagnosed AT originating from CS and terminated with several radiofrequency ablations (RFA) around CS. The diagnosis of slow-fast AVNRT, however, was somewhat difficult due to the following findings: (1) small amount of adenosine triphosphate (ATP) could terminate slow-fast AVNRT reproducibly; (2) we could provoke slow-fast AVNRT only by RV pacing with isoproterenol infusion. With other electrophysiological findings, we diagnosed slow-fast AVNRT. Radiofrequency energy was delivered initially in the posteroseptal region, followed by inside CS, and finally in the middle septal region, which completed the slow pathway ablation. After the procedure, we could never provoke these arrhythmias. <Learning objective: Coexistence of focal AT originating from CS with slow-fast AVNRT is a rare phenomenon. Furthermore, slow-fast AVNRT could show unusual characteristic as following: (1) small amount of ATP terminates slow-fast AVNRT; (2) atrial pacing never provoked slow-fast AVNRT with isoproterenol infusion whereas ventricular pacing did, which depends on the physiological characteristic of the dual AV nodal pathway. Accordingly, we should precisely assess the obtained electrophysiological findings.>.
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Affiliation(s)
- Kyoichiro Yazaki
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Kenji Enta
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Shohei Kataoka
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Mitsuru Kahata
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Asako Kumagai
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Koji Inoue
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Hiroshi Koganei
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Masato Otsuka
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
| | - Yasuhiro Ishii
- Department of Cardiology, Cardiovascular Center, Ogikubo Hospital, Tokyo, Japan
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15
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Uemura K, Inagaki M, Zheng C, Kawada T, Li M, Fukumitsu M, Sugimachi M. Acute ivabradine treatment reduces heart rate without increasing atrial fibrillation inducibility irrespective of underlying vagal activity in dogs. Heart Vessels 2017; 32:484-94. [PMID: 27844147 DOI: 10.1007/s00380-016-0922-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/11/2016] [Indexed: 01/11/2023]
Abstract
Ivabradine, a bradycardic agent, has been shown to stably reduce patient's heart rate (HR) in the setting of acute cardiac care. However, an association between atrial fibrillation (AF) risk and acute ivabradine treatment remains a controversial clinical issue, and has not been thoroughly investigated. Bradycardia and abnormal atrial refractoriness induced by ivabradine treatment may enhance vulnerability to AF induction, especially when vagal nerve is concurrently activated. We aimed to experimentally investigate the effects of acute ivabradine treatment with/without concurrent vagal activation on AF inducibility. In 16 anesthetized dogs, cervical vagal nerves were prepared for electrical stimulation (VS). AF induction rate (AFIR) was determined by atrial burst pacing. HR, atrial action potential duration (APD), atrial effective refractory period (ERP), and AFIR were obtained consecutively at baseline, during delivery of VS (VS alone), after intravenous injection of ivabradine 0.5 mg/kg (n = 8, ivabradine group) or saline (n = 8, saline group), and again during VS delivery (drug+VS). In the ivabradine group, ivabradine alone significantly lowered HR compared to baseline, while ivabradine+VS significantly lowered HR compared to VS alone. Contrary to expectations, there were no significant differences in trends of APD, temporal dispersion of APD, ERP, and AFIR between ivabradine and saline groups. Irrespective of whether ivabradine or saline was injected, VS significantly shortened APD and ERP, and increased AFIR. Interestingly, although bradycardia in response to ivabradine injection was more intense than that to VS alone, AFIR was significantly lower after ivabradine injection than during VS alone. We conclude that, despite its intense bradycardic effect, acute ivabradine treatment does not increase AF inducibility irrespective of underlying vagal activity. This study may constitute support for the safety of using ivabradine in the setting of acute cardiac care.
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