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Nishimura A, Harada M, Ashihara T, Nomura Y, Motoike Y, Koshikawa M, Ito T, Watanabe E, Ozaki Y, Izawa H. Effect of pulmonary vein isolation on rotor/multiple wavelet dynamics in persistent atrial fibrillation, association with vagal response and implications for adjunctive ablation. Heart Vessels 2022; 38:699-710. [PMID: 36436027 PMCID: PMC10085924 DOI: 10.1007/s00380-022-02209-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/16/2022] [Indexed: 11/29/2022]
Abstract
AbstractPersistent atrial fibrillation (PeAF) may develop arrhythmogenic substrates of rotors/multiple wavelets. However, the ways in which pulmonary vein isolation (PVI) affects the dynamics of rotor/multiple wavelets in PeAF patients remain elusive. Real-time phase-mapping (ExTRa mapping, EXT) in the whole left atrium (LA) was performed during PeAF before and after PVI (n = 111). The percentage of time in which rotor/multiple wavelets (phase singularities) was observed during each 5-s phase-mapping recording (non-passive activation ratio, %NP) was measured as an index of its burden. The mapping areas showing %NP ≥ 50% were defined as rotor/multiple-wavelet substrates (RSs). Before PVI, RSs were globally distributed in the LA. After PVI, %NP decreased (< 50%) in many RSs (PVI-modifiable RSs) but remained high (≥ 50%) in some RSs, especially localized in the anterior/septum/inferior regions (PVI-unmodifiable RSs, 2.3 ± 1.0 areas/patient). Before PVI, vagal response (VR) to high-frequency stimulation was observed in 23% of RSs, especially localized in the inferior region. VR disappearance after PVI was more frequently observed in PVI-modifiable RSs (79%) than in PVI-unmodifiable RSs (55%, p < 0.05), suggesting that PVI affects autonomic nerve activities and rotor/multiple wavelet dynamics. PVI-unmodifiable RSs were adjunctively ablated in 104 patients. The 1-year AT/AF-free survival rate was 70% in those with PVI alone (n = 115), and 86% in patients with the adjunctive ablation (log-rank test = 7.65, p < 0.01). PVI suppresses not only ectopic firing but also rotor/multiple wavelets partly via modification of autonomic nerve activities. The adjunctive ablation of PVI-unmodifiable RSs improved the outcome in PeAF patients and might be a novel ablation strategy beyond PVI.
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Affiliation(s)
- Asuka Nishimura
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Masahide Harada
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan.
| | - Takashi Ashihara
- Information Technology and Management Center, Shiga University of Medical Science, Seta Tsukinowa-Cho, Otsu, Shiga, 5202192, Japan
| | - Yoshihiro Nomura
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Yuji Motoike
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Masayuki Koshikawa
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Takehiro Ito
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Eiichi Watanabe
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Yukio Ozaki
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
| | - Hideo Izawa
- Department of Cardiology, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-Cho, Toyoake, Aichi, 4701192, Japan
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Ono K, Iwasaki YK, Akao M, Ikeda T, Ishii K, Inden Y, Kusano K, Kobayashi Y, Koretsune Y, Sasano T, Sumitomo N, Takahashi N, Niwano S, Hagiwara N, Hisatome I, Furukawa T, Honjo H, Maruyama T, Murakawa Y, Yasaka M, Watanabe E, Aiba T, Amino M, Itoh H, Ogawa H, Okumura Y, Aoki-Kamiya C, Kishihara J, Kodani E, Komatsu T, Sakamoto Y, Satomi K, Shiga T, Shinohara T, Suzuki A, Suzuki S, Sekiguchi Y, Nagase S, Hayami N, Harada M, Fujino T, Makiyama T, Maruyama M, Miake J, Muraji S, Murata H, Morita N, Yokoshiki H, Yoshioka K, Yodogawa K, Inoue H, Okumura K, Kimura T, Tsutsui H, Shimizu W. JCS/JHRS 2020 Guideline on Pharmacotherapy of Cardiac Arrhythmias. Circ J 2022; 86:1790-1924. [DOI: 10.1253/circj.cj-20-1212] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | - Yu-ki Iwasaki
- Department of Cardiovascular Medicine, Nippon Medical School
| | - Masaharu Akao
- Department of Cardiovascular Medicine, National Hospital Organization Kyoto Medical Center
| | - Takanori Ikeda
- Department of Cardiovascular Medicine, Toho University Graduate School of Medicine
| | - Kuniaki Ishii
- Department of Pharmacology, Yamagata University Faculty of Medicine
| | - Yasuya Inden
- Department of Cardiology, Nagoya University Graduate School of Medicine
| | - Kengo Kusano
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Yoshinori Kobayashi
- Division of Cardiology, Department of Medicine, Tokai University Hachioji Hospital
| | | | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Naokata Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center
| | - Naohiko Takahashi
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University
| | - Shinichi Niwano
- Department of Cardiovascular Medicine, Kitasato University School of Medicine
| | | | | | - Tetsushi Furukawa
- Department of Bio-information Pharmacology, Medical Research Institute, Tokyo Medical and Dental University
| | - Haruo Honjo
- Research Institute of Environmental Medicine, Nagoya University
| | - Toru Maruyama
- Department of Hematology, Oncology and Cardiovascular Medicine, Kyushu University Hospital
| | - Yuji Murakawa
- The 4th Department of Internal Medicine, Teikyo University School of Medicine, Mizonokuchi Hospital
| | - Masahiro Yasaka
- Department of Cerebrovascular Medicine and Neurology, Clinical Research Institute, National Hospital Organization Kyushu Medical Center
| | - Eiichi Watanabe
- Department of Cardiology, Fujita Health University School of Medicine
| | - Takeshi Aiba
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Mari Amino
- Department of Cardiovascular Medicine, Tokai University School of Medicine
| | - Hideki Itoh
- Division of Patient Safety, Hiroshima University Hospital
| | - Hisashi Ogawa
- Department of Cardiology, National Hospital Organisation Kyoto Medical Center
| | - Yasuo Okumura
- Division of Cardiology, Department of Medicine, Nihon University School of Medicine
| | - Chizuko Aoki-Kamiya
- Department of Obstetrics and Gynecology, National Cerebral and Cardiovascular Center
| | - Jun Kishihara
- Department of Cardiovascular Medicine, Kitasato University School of Medicine
| | - Eitaro Kodani
- Department of Cardiovascular Medicine, Nippon Medical School Tama Nagayama Hospital
| | - Takashi Komatsu
- Division of Cardiology, Department of Internal Medicine, Iwate Medical University School of Medicine
| | | | | | - Tsuyoshi Shiga
- Department of Clinical Pharmacology and Therapeutics, The Jikei University School of Medicine
| | - Tetsuji Shinohara
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University
| | - Atsushi Suzuki
- Department of Cardiology, Tokyo Women's Medical University
| | - Shinya Suzuki
- Department of Cardiovascular Medicine, The Cardiovascular Institute
| | - Yukio Sekiguchi
- Department of Cardiology, National Hospital Organization Kasumigaura Medical Center
| | - Satoshi Nagase
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center
| | - Noriyuki Hayami
- Department of Fourth Internal Medicine, Teikyo University Mizonokuchi Hospital
| | | | - Tadashi Fujino
- Department of Cardiovascular Medicine, Toho University, Faculty of Medicine
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Mitsunori Maruyama
- Department of Cardiovascular Medicine, Nippon Medical School Musashi Kosugi Hospital
| | - Junichiro Miake
- Department of Pharmacology, Tottori University Faculty of Medicine
| | - Shota Muraji
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center
| | | | - Norishige Morita
- Division of Cardiology, Department of Medicine, Tokai University Hachioji Hospital
| | - Hisashi Yokoshiki
- Department of Cardiovascular Medicine, Sapporo City General Hospital
| | - Koichiro Yoshioka
- Division of Cardiology, Department of Internal Medicine, Tokai University School of Medicine
| | - Kenji Yodogawa
- Department of Cardiovascular Medicine, Nippon Medical School
| | | | - Ken Okumura
- Division of Cardiology, Saiseikai Kumamoto Hospital Cardiovascular Center
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Faculty of Medical Sciences, Kyushu University
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School
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Shibata N, Inada S, Nakazawa K, Ashihara T, Tomii N, Yamazaki M, Honjo H, Seno H, Sakuma I. Mechanism of Ventricular Fibrillation: Current Status and Problems. ADVANCED BIOMEDICAL ENGINEERING 2022. [DOI: 10.14326/abe.11.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Nitaro Shibata
- Department of Cardiology, Shinjuku Mitsui Building Clinic
| | - Shin Inada
- Faculty of Medical Science Technology, Morinomiya University of Medical Sciences
| | - Kazuo Nakazawa
- Faculty of Medical Science Technology, Morinomiya University of Medical Sciences
| | - Takashi Ashihara
- Department of Medical Informatics and Biomedical Engineering, Shiga University of Medical Science
| | - Naoki Tomii
- Department of Precision Engineering, The University of Tokyo
| | | | - Haruo Honjo
- Health Promotion Division, Toyota Autobody Co. Ltd
| | - Hiroshi Seno
- Department of Precision Engineering, The University of Tokyo
| | - Ichiro Sakuma
- Medical Device Development and Regulation Research Center, The University of Tokyo
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El Farissi M, Keulards DCJ, Zelis JM, van 't Veer M, Zimmermann FM, Pijls NHJ, Otterspoor LC. Hypothermia for Reduction of Myocardial Reperfusion Injury in Acute Myocardial Infarction: Closing the Translational Gap. Circ Cardiovasc Interv 2021; 14:e010326. [PMID: 34266310 DOI: 10.1161/circinterventions.120.010326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Myocardial reperfusion injury-triggered by an inevitable inflammatory response after reperfusion-may undo a considerable part of the myocardial salvage achieved through timely percutaneous coronary intervention in patients with acute myocardial infarction. Because infarct size is strongly correlated to mortality and risk of heart failure, the importance of endeavors for cardioprotective therapies to attenuate myocardial reperfusion injury and decrease infarct size remains undisputed. Myocardial reperfusion injury is the result of several complex nonlinear phenomena, and for a therapy to be effective, it should act on multiple targets involved in this injury. In this regard, hypothermia remains a promising treatment despite a number of negative randomized controlled trials in humans with acute myocardial infarction so far. To turn the tide for hypothermia in patients with acute myocardial infarction, sophisticated solutions for important limitations of systemic hypothermia should continue to be developed. In this review, we provide a comprehensive overview of the pathophysiology and clinical expression of myocardial reperfusion injury and discuss the current status and possible future of hypothermia for cardioprotection in patients with acute myocardial infarction.
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Affiliation(s)
- Mohamed El Farissi
- Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands
| | | | - Jo M Zelis
- Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands
| | - Marcel van 't Veer
- Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands
| | | | - Nico H J Pijls
- Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands
| | - Luuk C Otterspoor
- Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands
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Tomita A, Fujimoto T, Takada S, Hayashi Y. Anesthetic management of a patient with severe aortic regurgitation undergoing reoperation for ascending aorta false aneurysm using hypothermia: prevention of ventricular fibrillation by nifekalant. JA Clin Rep 2021; 7:43. [PMID: 34018058 PMCID: PMC8137800 DOI: 10.1186/s40981-021-00446-8] [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: 02/25/2021] [Revised: 04/16/2021] [Accepted: 05/13/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To prevent cardiac collapse and to protect cerebral function, hypothermic cardiopulmonary bypass is established before resternotomy. However, ventricular fibrillation under hypothermia facilitates left ventricular distension, which causes irreversible myocardial damage when the patient has aortic regurgitation. We report a case of successful management in preventing ventricular fibrillation under hypothermia by using nifekalant. CASE PRESENTATION A 56-year-old male, who had been performed a David operation, was scheduled for a Bentall operation for a pseudo aortic aneurysm with severe aortic regurgitation. After inducing anesthesia, we administered intravenous nifekalant and a vent tube was inserted into the left ventricle under one-lung ventilation. Extracorporeal circulation was established and resternotomy started after cooling to 27 °C. Although severe bradycardia and QT prolongation were observed, ventricular fibrillation did not occur until aortic cross-clamping. CONCLUSION Combining maintaining cerebral perfusion and avoiding left ventricle distension during hypothermia was successfully managed with nifekalant in our redo cardiac patient with aortic regurgitation.
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Affiliation(s)
- Akiko Tomita
- Anesthesiology Service, Sakurabashi-Watanabe Hospital, Osaka, Japan. .,Present address: Anesthesiology Service, Osaka City General Hospital, 2-13-22 Miyakojima-hondori, Miyakojima-ku, Osaka, 531-0021, Japan.
| | - Tomoko Fujimoto
- Anesthesiology Service, Sakurabashi-Watanabe Hospital, Osaka, Japan
| | - Shoko Takada
- Anesthesiology Service, Sakurabashi-Watanabe Hospital, Osaka, Japan
| | - Yukio Hayashi
- Anesthesiology Service, Sakurabashi-Watanabe Hospital, Osaka, Japan
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Dietrichs ES, Tveita T, Smith G. Hypothermia and cardiac electrophysiology: a systematic review of clinical and experimental data. Cardiovasc Res 2020; 115:501-509. [PMID: 30544147 DOI: 10.1093/cvr/cvy305] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 12/17/2022] Open
Abstract
Moderate therapeutic hypothermia procedures are used in post-cardiac arrest care, while in surgical procedures, lower core temperatures are often utilized to provide cerebral protection. Involuntary reduction of core body temperature takes place in accidental hypothermia and ventricular arrhythmias are recognized as a principal cause for a high mortality rate in these patients. We assessed both clinical and experimental literature through a systematic literature search in the PubMed database, to review the effect of hypothermia on cardiac electrophysiology. From included studies, there is common experimental and clinical evidence that progressive cooling will induce changes in cardiac electrophysiology. The QT interval is prolonged and appears more sensitive to decreases in temperature than the QRS interval. Severe hypothermia is associated with more pronounced changes, some of which are proarrhythmic. This is supported clinically where severe accidental hypothermia is commonly associated with ventricular fibrillation or asystole. J-waves in human electrocardiogram recordings are regularly but not always observed in hypothermia. Its relation to ventricular repolarization and arrhythmias is not obvious. Little clinical data exist on efficacy of anti-arrhythmic drugs in hypothermia, while experimental data show the potential of some agents, such as the class III antiarrhythmic bretylium. It is apparent that QT-prolonging drugs should be avoided.
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Affiliation(s)
- Erik Sveberg Dietrichs
- Department of Medical Biology, Experimental and Clinical Pharmacology Research Group, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Diagnostic Services, Department of Clinical Pharmacology, University Hospital of North Norway, Tromsø, Norway
| | - Torkjel Tveita
- Department of Clinical Medicine, Anesthesia and Critical Care Research Group, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Godfrey Smith
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow, UK
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Hsieh YC, Hsieh WH, Li CH, Liao YC, Lin JC, Weng CJ, Lo MT, Tuan TC, Lin SF, Yeh HI, Huang JL, Haugan K, Larsen BD, Lin YJ, Lin WW, Wu TJ, Chen SA. Ventricular divergence correlates with epicardial wavebreaks and predicts ventricular arrhythmia in isolated rabbit hearts during therapeutic hypothermia. PLoS One 2020; 15:e0228818. [PMID: 32084145 PMCID: PMC7034916 DOI: 10.1371/journal.pone.0228818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/23/2020] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION High beat-to-beat morphological variation (divergence) on the ventricular electrogram during programmed ventricular stimulation (PVS) is associated with increased risk of ventricular fibrillation (VF), with unclear mechanisms. We hypothesized that ventricular divergence is associated with epicardial wavebreaks during PVS, and that it predicts VF occurrence. METHOD AND RESULTS Langendorff-perfused rabbit hearts (n = 10) underwent 30-min therapeutic hypothermia (TH, 30°C), followed by a 20-min treatment with rotigaptide (300 nM), a gap junction modifier. VF inducibility was tested using burst ventricular pacing at the shortest pacing cycle length achieving 1:1 ventricular capture. Pseudo-ECG (p-ECG) and epicardial activation maps were simultaneously recorded for divergence and wavebreaks analysis, respectively. A total of 112 optical and p-ECG recordings (62 at TH, 50 at TH treated with rotigaptide) were analyzed. Adding rotigaptide reduced ventricular divergence, from 0.13±0.10 at TH to 0.09±0.07 (p = 0.018). Similarly, rotigaptide reduced the number of epicardial wavebreaks, from 0.59±0.73 at TH to 0.30±0.49 (p = 0.036). VF inducibility decreased, from 48±31% at TH to 22±32% after rotigaptide infusion (p = 0.032). Linear regression models showed that ventricular divergence correlated with epicardial wavebreaks during TH (p<0.001). CONCLUSION Ventricular divergence correlated with, and might be predictive of epicardial wavebreaks during PVS at TH. Rotigaptide decreased both the ventricular divergence and epicardial wavebreaks, and reduced the probability of pacing-induced VF during TH.
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Affiliation(s)
- Yu-Cheng Hsieh
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Data Science and Big Data Analytics and Department of Financial Engineering, Providence University, Taichung, Taiwan
- * E-mail:
| | - Wan-Hsin Hsieh
- Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Cheng-Hung Li
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Data Science and Big Data Analytics and Department of Financial Engineering, Providence University, Taichung, Taiwan
| | - Ying-Chieh Liao
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Data Science and Big Data Analytics and Department of Financial Engineering, Providence University, Taichung, Taiwan
| | - Jiunn-Cherng Lin
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Data Science and Big Data Analytics and Department of Financial Engineering, Providence University, Taichung, Taiwan
| | - Chi-Jen Weng
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Department of Data Science and Big Data Analytics and Department of Financial Engineering, Providence University, Taichung, Taiwan
| | - Men-Tzung Lo
- Research Center for Adaptive Data Analysis, National Central University, Jhongli City, Taiwan
| | - Ta-Chuan Tuan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shien-Fong Lin
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
- Institute of Biomedical Engineering, National Chiao-Tung University, Hsinchu, Taiwan
| | - Hung-I Yeh
- Departments of Internal Medicine and Medical Research, Mackay Memorial Hospital, Mackay Medical College, New Taipei City, Taiwan
| | - Jin-Long Huang
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Ketil Haugan
- Department of Cardiology, Zealand University Hospital, Roskilde, Denmark
| | | | - Yenn-Jiang Lin
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Wei-Wen Lin
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Life Science, Tunghai University, Taichung, Taiwan
| | - Tsu-Juey Wu
- Cardiovascular Center, Taichung Veterans General Hospital and Chiayi Branch, Taichung and Chiayi, Taiwan
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Shih-Ann Chen
- Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
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Saitoh O, Watanabe J, Oikawa A, Sugai A, Furushima H, Chinushi M. Therapy-Resistant Ventricular Arrhythmias Developed More Often in Advanced Than in Therapeutic Mild Hypothermic Condition. Int Heart J 2019; 60:1161-1167. [PMID: 31484866 DOI: 10.1536/ihj.18-711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Therapy-resistant ventricular arrhythmias can occur during accidental advanced hypothermic conditions. On the other hand, hypothermic therapy using mild cooling has been successfully accomplished with infrequent ventricular arrhythmia events.To further clarify the therapeutic-resistant arrhythmogenic substrate which develops in hypothermic conditions, an experimental study was performed using a perfusion wedge preparation model of porcine ventricle, and electrophysiological characteristics, inducibility of ventricular arrhythmias, and effects of therapeutic interventions were assessed at 3 target temperatures (37, 32 and 28°C).As the myocardial temperature decreased, myocardial contractions and the number of spontaneous beats deceased. Depolarization (QRS width, stimulus-QRS interval) and repolarization (QT interval, ERP) parameters progressively increased, and dispersion of the ventricular repolarization increased. At 28°C, VF tended to be inducible more frequently (1/11 at 37°C, 1/11 at 32°C, and 5/11 hearts at 28°C), and some VFs at 28°C required greater defibrillation energy to resume basic rhythm.An advanced but not a mild hypothermic condition had an enhanced arrhythmogenic potential in our model. In the advanced hypothermic condition, VF with relatively prolonged F-F intervals and a greater defibrillation energy were occasionally inducible based on the arrhythmogenic substrate characterized as slowed conduction and prolonged repolarization of the ventricle.
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Affiliation(s)
- Osamu Saitoh
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
| | - Junya Watanabe
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
| | - Ayaka Oikawa
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
| | - Ayari Sugai
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
| | - Hiroshi Furushima
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
| | - Masaomi Chinushi
- Cardiovascular Research of Graduate School of Health Sciences, Niigata University School of Medicine
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Lions S, Dragu R, Carsenty Y, Zukermann R, Aronson D. Determinants of cardiac repolarization and risk for ventricular arrhythmias during mild therapeutic hypothermia. J Crit Care 2019; 46:151-156. [PMID: 29929706 DOI: 10.1016/j.jcrc.2018.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 03/06/2018] [Accepted: 03/06/2018] [Indexed: 11/20/2022]
Abstract
PURPOSE We aimed to investigate the factors that modulate the extent of QTc prolongation and potential arrhythmogenic consequences during mild therapeutic hypothermia (MTH). METHODS We studied 205 patients after out-of-hospital cardiac arrest (131 underwent MTH). QTc was measured at baseline, 3h, 6h, 12h, 24h (end of hypothermia), 48h and 72h, and ventricular arrhythmias quantified. RESULTS During MTH, the QTc interval increased progressively peaking at 12h (mean increase 42ms, 95% CI 30-55). There was a strong gender effect (P<0.001) and a significant gender-by-MTH interaction (P=0.004). At 12h, the QTc interval was markedly longer in women as compared with men (mean difference 50ms [95% CI 27-73]. Anoxic brain injury (P=0.002) was also positively associated with QTc prolongation. The risk for ventricular arrhythmic events was not higher with MTH compared with no hypothermia (incidence rate ratio 0.57, 95% CI 0.32-1.02, P=0.06). However, typical cases of Torsade de pointes occurred in association with AV block and LQT2. CONCLUSION QTc prolongation during MTH is strongly affected by female gender and moderately by concomitant anoxic brain injury. Although the overall risk for ventricular arrhythmias is not greater with MTH, Torsade de pointes may develop when other contributing factors coexist.
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Affiliation(s)
- Svetlana Lions
- Department of Cardiology, Rambam Medical Center, Haifa, Israel; Ruth & Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Israel
| | - Robert Dragu
- Department of Cardiology, Rambam Medical Center, Haifa, Israel; Ruth & Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Israel
| | - Yoav Carsenty
- Department of Cardiology, Rambam Medical Center, Haifa, Israel; Ruth & Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Israel
| | - Robert Zukermann
- Department of Cardiology, Rambam Medical Center, Haifa, Israel; Ruth & Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Israel
| | - Doron Aronson
- Department of Cardiology, Rambam Medical Center, Haifa, Israel; Ruth & Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Israel.
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10
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Kienast R, Handler M, Stöger M, Baumgarten D, Hanser F, Baumgartner C. Modeling hypothermia induced effects for the heterogeneous ventricular tissue from cellular level to the impact on the ECG. PLoS One 2017; 12:e0182979. [PMID: 28813535 PMCID: PMC5558962 DOI: 10.1371/journal.pone.0182979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/27/2017] [Indexed: 11/18/2022] Open
Abstract
Hypothermia has a profound impact on the electrophysiological mechanisms of the heart. Experimental investigations provide a better understanding of electrophysiological alterations associated with cooling. However, there is a lack of computer models suitable for simulating the effects of hypothermia in cardio-electrophysiology. In this work, we propose a model that describes the cooling-induced electrophysiological alterations in ventricular tissue in a temperature range from 27°C to 37°C. To model the electrophysiological conditions in a 3D left ventricular tissue block it was essential to consider the following anatomical and physiological parameters in the model: the different cell types (endocardial, M, epicardial), the heterogeneous conductivities in longitudinal, transversal and transmural direction depending on the prevailing temperature, the distinct fiber orientations and the transmural repolarization sequences. Cooling-induced alterations on the morphology of the action potential (AP) of single myocardial cells thereby are described by an extension of the selected Bueno-Orovio model for human ventricular tissue using Q10 temperature coefficients. To evaluate alterations on tissue level, the corresponding pseudo electrocardiogram (pECG) was calculated. Simulations show that cooling-induced AP and pECG-related parameters, i.e. AP duration, morphology of the notch of epicardial AP, maximum AP upstroke velocity, AP rise time, QT interval, QRS duration and J wave formation are in good accordance with literature and our experimental data. The proposed model enables us to further enhance our knowledge of cooling-induced electrophysiological alterations from cellular to tissue level in the heart and may help to better understand electrophysiological mechanisms, e.g. in arrhythmias, during hypothermia.
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Affiliation(s)
- Roland Kienast
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- * E-mail:
| | - Michael Handler
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Markus Stöger
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Ilmenau, Germany
| | - Friedrich Hanser
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Christian Baumgartner
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Health Care Engineering with European Testing Center of Medical Devices, Graz University of Technology, Graz, Austria
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11
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Tomii N, Yamazaki M, Arafune T, Honjo H, Shibata N, Sakuma I. Detection Algorithm of Phase Singularity Using Phase Variance Analysis for Epicardial Optical Mapping Data. IEEE Trans Biomed Eng 2016; 63:1795-1803. [DOI: 10.1109/tbme.2015.2502726] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Gap junction modifier rotigaptide decreases the susceptibility to ventricular arrhythmia by enhancing conduction velocity and suppressing discordant alternans during therapeutic hypothermia in isolated rabbit hearts. Heart Rhythm 2016; 13:251-61. [DOI: 10.1016/j.hrthm.2015.07.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Indexed: 11/23/2022]
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13
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Kudlicka J, Mlcek M, Belohlavek J, Hala P, Lacko S, Janak D, Havranek S, Malik J, Janota T, Ostadal P, Neuzil P, Kittnar O. Inducibility of ventricular fibrillation during mild therapeutic hypothermia: electrophysiological study in a swine model. J Transl Med 2015; 13:72. [PMID: 25886318 PMCID: PMC4342808 DOI: 10.1186/s12967-015-0429-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 02/05/2015] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Mild therapeutic hypothermia (MTH) is being used after cardiac arrest for its expected improvement in neurological outcome. Safety of MTH concerning inducibility of malignant arrhythmias has not been satisfactorily demonstrated. This study compares inducibility of ventricular fibrillation (VF) before and after induction of MTH in a whole body swine model and evaluates possible interaction with changing potassium plasma levels. METHODS The extracorporeal cooling was introduced in fully anesthetized swine (n = 6) to provide MTH. Inducibility of VF was studied by programmed ventricular stimulation three times in each animal under the following: during normothermia (NT), after reaching the core temperature of 32°C (HT) and after another 60 minutes of stable hypothermia (HT60). Inducibility of VF, effective refractory period of the ventricles (ERP), QTc interval and potassium plasma levels were measured. RESULTS Starting at normothermia of 38.7 (IQR 38.2; 39.8)°C, HT was achieved within 54 (39; 59) minutes and the core temperature was further maintained constant. Overall, the inducibility of VF was 100% (18/18 attempts) at NT, 83% (15/18) after reaching HT (P = 0.23) and 39% (7/18) at HT60 (P = 0.0001) using the same protocol. Similarly, ERP prolonged from 140 (130; 150) ms at NT to 206 (190; 220) ms when reaching HT (P < 0.001) and remained 206 (193; 220) ms at HT60. QTc interval was inversely proportional to the core temperature and extended from 376 (362; 395) at NT to 570 (545; 599) ms at HT. Potassium plasma level changed spontaneously: decreased during cooling from 4.1 (3.9; 4.8) to 3.7 (3.4; 4.1) mmol/L at HT (P < 0.01), then began to increase and returned to baseline level at HT60 (4.6 (4.4; 5.0) mmol/L, P = NS). CONCLUSIONS According to our swine model, MTH does not increase the risk of VF induction by ventricular pacing in healthy hearts. Moreover, when combined with normokalemia, MTH exerts an antiarrhythmic effect despite prolonged QTc interval.
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Affiliation(s)
- Jaroslav Kudlicka
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
- 3rd Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Mikulas Mlcek
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
| | - Jan Belohlavek
- 2nd Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Pavel Hala
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
- Department of Cardiology, Na Homolce Hospital, Roentgenova 2/37, Prague 5, 150 30, Czech Republic.
| | - Stanislav Lacko
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
| | - David Janak
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
- 2nd Department of Surgery, Cardiovascular Surgery, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Stepan Havranek
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
- 2nd Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Jan Malik
- 3rd Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Tomas Janota
- 3rd Department of Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital, U Nemocnice 2, Prague 2, 128 00, Czech Republic.
| | - Petr Ostadal
- Department of Cardiology, Na Homolce Hospital, Roentgenova 2/37, Prague 5, 150 30, Czech Republic.
| | - Petr Neuzil
- Department of Cardiology, Na Homolce Hospital, Roentgenova 2/37, Prague 5, 150 30, Czech Republic.
| | - Otomar Kittnar
- Department of Physiology, First Faculty of Medicine, Charles University in Prague, Albertov 5, Prague 2, 128 00, Czech Republic.
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14
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When better is the enemy of good: the optimal heart rate during therapeutic cooling. Crit Care Med 2014; 42:2452-4. [PMID: 25319912 DOI: 10.1097/ccm.0000000000000600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Koutbi L, Chenu C, Macé L, Franceschi F. Ablation of idiopathic ventricular tachycardia arising from posterior mitral annulus in an 11-month-old infant by transapical left ventricular access via median sternotomy. Heart Rhythm 2014; 12:430-2. [PMID: 25444854 DOI: 10.1016/j.hrthm.2014.10.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Linda Koutbi
- APHM, Department of Cardiology, Timone University Hospital, Marseille, France
| | - Caroline Chenu
- APHM, Department of Cardiac and Thoracic Surgery, Timone Children's Hospital, Marseille, France
| | - Loïc Macé
- APHM, Department of Cardiac and Thoracic Surgery, Timone Children's Hospital, Marseille, France
| | - Frédéric Franceschi
- APHM, Department of Cardiology, Timone University Hospital, Marseille, France.
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16
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Takemoto Y, Takanari H, Honjo H, Ueda N, Harada M, Kato S, Yamazaki M, Sakuma I, Opthof T, Kodama I, Kamiya K. Inhibition of intercellular coupling stabilizes spiral-wave reentry, whereas enhancement of the coupling destabilizes the reentry in favor of early termination. Am J Physiol Heart Circ Physiol 2012; 303:H578-86. [PMID: 22707561 DOI: 10.1152/ajpheart.00355.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spiral-wave (SW) reentry is a major organizing principle of ventricular tachycardia/fibrillation (VT/VF). We tested a hypothesis that pharmacological modification of gap junction (GJ) conductance affects the stability of SW reentry in a two-dimensional (2D) epicardial ventricular muscle layer prepared by endocardial cryoablation of Langendorff-perfused rabbit hearts. Action potential signals were recorded and analyzed by high-resolution optical mapping. Carbenoxolone (CBX; 30 μM) and rotigaptide (RG, 0.1 μM) were used to inhibit and enhance GJ coupling, respectively. CBX decreased the space constant (λ) by 36%, whereas RG increased it by 22-24% (n = 5; P < 0.01). During centrifugal propagation, there was a linear relationship between the wavefront curvature (κ) and local conduction velocity (LCV): LCV = LCV(0) - D·κ (D, diffusion coefficient; LCV(0), LCV at κ = 0). CBX decreased LCV(0) and D by 27 ± 3 and 57 ± 3%, respectively (n = 5; P < 0.01). RG increased LCV(0) and D by 18 ± 3 and 54 ± 5%, respectively (n = 5, P < 0.01). The regression lines with and without RG crossed, resulting in a paradoxical decrease of LCV with RG at κ > ~60 cm(-1). SW reentry induced after CBX was stable, and the incidence of sustained VTs (>30 s) increased from 38 ± 4 to 85 ± 4% after CBX (n = 18; P < 0.01). SW reentry induced after RG was characterized by decremental conduction near the rotation center, prominent drift and self-termination by collision with the anatomical boundaries, and the incidence of sustained VTs decreased from 40 ± 5 to 17 ± 6% after RG (n = 13; P < 0.05). These results suggest that decreased intercellular coupling stabilizes SW reentry in 2D cardiac muscle, whereas increased coupling facilitates its early self-termination.
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Affiliation(s)
- Yoshio Takemoto
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
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17
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Therapeutic hypothermia: a state-of-the-art emergency medicine perspective. Am J Emerg Med 2012; 30:800-10. [DOI: 10.1016/j.ajem.2011.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 03/13/2011] [Accepted: 03/15/2011] [Indexed: 01/06/2023] Open
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18
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Kato S, Honjo H, Takemoto Y, Takanari H, Suzuki T, Okuno Y, Opthof T, Sakuma I, Inada S, Nakazawa K, Ashihara T, Kodama I, Kamiya K. Pharmacological Blockade of IKs Destabilizes Spiral-Wave Reentry Under β-Adrenergic Stimulation in Favor of Its Early Termination. J Pharmacol Sci 2012; 119:52-63. [DOI: 10.1254/jphs.12008fp] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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19
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Erlinge D. A Review of Mild Hypothermia as an Adjunctive Treatment for ST-Elevation Myocardial Infarction. Ther Hypothermia Temp Manag 2011; 1:129-41. [DOI: 10.1089/ther.2011.0008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- David Erlinge
- Department of Cardiology, Lund University, Skane University Hospital, Lund, Sweden
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20
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Lou Q, Li W, Efimov IR. The role of dynamic instability and wavelength in arrhythmia maintenance as revealed by panoramic imaging with blebbistatin vs. 2,3-butanedione monoxime. Am J Physiol Heart Circ Physiol 2011; 302:H262-9. [PMID: 22037192 DOI: 10.1152/ajpheart.00711.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Unlike other excitation-contraction uncouplers, blebbistatin has few electrophysiological side effects and has gained increasing acceptance as an excitation-contraction uncoupler in optical mapping experiments. However, the possible role of blebbistatin in ventricular arrhythmia has hitherto been unknown. Furthermore, experiments with blebbistatin and 2,3-butanedione monoxime (BDM) offer an opportunity to assess the contribution of dynamic instability and wavelength of impulse propagation to the induction and maintenance of ventricular arrhythmia. Recordings of monophasic action potentials were used to assess effects of blebbistatin in Langendorff-perfused rabbit hearts (n = 5). Additionally, panoramic optical mapping experiments were conducted in rabbit hearts (n = 7) that were sequentially perfused with BDM, then washed out, and subsequently perfused with blebbistatin. The susceptibility to arrhythmia was investigated using a shock-on-T protocol. We found that 1) application of blebbistatin did not change action potential duration (APD) restitution; 2) in contrast to blebbistatin, BDM flattened APD restitution curve and reduced the wavelength; and 3) incidence of sustained arrhythmia was much lower under blebbistatin than under BDM (2/123 vs. 23/99). While arrhythmias under BDM were able to stabilize, the arrhythmias under blebbistatin were unstable and terminated spontaneously. In conclusion, the lower susceptibility to arrhythmia under blebbistatin than under BDM indicates that blebbistatin has less effects on arrhythmia dynamics. A steep restitution slope under blebbistatin is associated with higher dynamic instability, manifested by the higher incidence of not only wave breaks but also wave extinctions. This relatively high dynamic instability leads to the self-termination of arrhythmia because of the sufficiently long wavelength under blebbistatin.
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Affiliation(s)
- Qing Lou
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-4899, USA
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21
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Yamazaki M, Honjo H, Ashihara T, Harada M, Sakuma I, Nakazawa K, Trayanova N, Horie M, Kalifa J, Jalife J, Kamiya K, Kodama I. Regional cooling facilitates termination of spiral-wave reentry through unpinning of rotors in rabbit hearts. Heart Rhythm 2011; 9:107-14. [PMID: 21839044 DOI: 10.1016/j.hrthm.2011.08.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
BACKGROUND Moderate global cooling of myocardial tissue was shown to destabilize 2-dimensional (2-D) reentry and facilitate its termination. OBJECTIVE This study sought to test the hypothesis that regional cooling destabilizes rotors and facilitates termination of spontaneous and DC shock-induced subepicardial reentry in isolated, endocardially ablated rabbit hearts. METHODS Fluorescent action potential signals were recorded from 2-D subepicardial ventricular myocardium of Langendorff-perfused rabbit hearts. Regional cooling (by 5.9°C ± 1.3°C) was applied to the left ventricular anterior wall using a transparent cooling device (10 mm in diameter). RESULTS Regional cooling during constant stimulation (2.5 Hz) prolonged the action potential duration (by 36% ± 9%) and slightly reduced conduction velocity (by 4% ± 4%) in the cooled region. Ventricular tachycardias (VTs) induced during regional cooling terminated earlier than those without cooling (control): VTs lasting >30 seconds were reduced from 17 of 39 to 1 of 61. When regional cooling was applied during sustained VTs (>120 seconds), 16 of 33 (48%) sustained VTs self-terminated in 12.5 ± 5.1 seconds. VT termination was the result of rotor destabilization, which was characterized by unpinning, drift toward the periphery of the cooled region, and subsequent collision with boundaries. The DC shock intensity required for cardioversion of the sustained VTs decreased significantly by regional cooling (22.8 ± 4.1 V, n = 16, vs 40.5 ± 17.6 V, n = 21). The major mode of reentry termination by DC shocks was phase resetting in the absence of cooling, whereas it was unpinning in the presence of cooling. CONCLUSION Regional cooling facilitates termination of 2-D reentry through unpinning of rotors.
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Affiliation(s)
- Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Chikusa-ku, Nagoya, Japan
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22
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Harada M, Tsuji Y, Ishiguro YS, Takanari H, Okuno Y, Inden Y, Honjo H, Lee JK, Murohara T, Sakuma I, Kamiya K, Kodama I. Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart. Am J Physiol Heart Circ Physiol 2011; 300:H565-73. [DOI: 10.1152/ajpheart.00209.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF ( n = 18) and control ( n = 17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs) >1,000 ms but significantly shorter at BCLs <400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17–81%), and conduction velocity was significantly decreased in CHF (by 6–20%). In both groups, high-frequency stimulation (BCLs <150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs <150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.
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Affiliation(s)
- Masahide Harada
- Department of Electrophysiology, Research Center of Montreal Heart Institute, Montreal, Quebec, Canada
| | - Yukiomi Tsuji
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Yuko S. Ishiguro
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Hiroki Takanari
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Yusuke Okuno
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Yasuya Inden
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya; and
| | - Haruo Honjo
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Jong-Kook Lee
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Toyoaki Murohara
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya; and
| | - Ichiro Sakuma
- Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
| | - Itsuo Kodama
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University
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New epicardial mapping electrode with warming/cooling function for experimental electrophysiology studies. Med Eng Phys 2011; 33:653-9. [PMID: 21256794 DOI: 10.1016/j.medengphy.2010.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 12/22/2010] [Accepted: 12/24/2010] [Indexed: 11/23/2022]
Abstract
Cardiac electrical activity is influenced by temperature. In experimental models, the induction of hypothermia and/or hyperthermia has been used for the study of mechanisms of cardiac arrhythmia. A system that allows for localized, controlled induction, besides simultaneously recording electrical activity in the same induced area, needs to be developed ad hoc. This article describes the construction and application of a new system capable of locally modifying the epicardial temperature of isolated hearts and of carrying out cardiac mapping with sufficient spatial resolution. The system is based on a thermoelectric refrigerator and an array of 128 stainless steel unipolar electrodes in encapsulated epoxy of good thermal conductivity. The surface of the electrode is shaped to match the ventricular curvature. The electrode-device was tested on 7 isolated perfused rabbit hearts following the Langendorff technique. Quality recordings were obtained for the left ventricle at temperatures of 37° C, 22° C and 42° C. The effects of temperature were explored in relation to two electrophysiological parameters: the QT interval during sinus rhythm and the VV interval during ventricular fibrillation. The results indicate that this is a suitable method for creating and analyzing electrophysiological heterogeneities induced by temperature in the experimental model.
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24
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Hsieh YC, Yeh HI, Lin SF, Hsu YW, Huang JL, Lin TC, Ting CT, Wu TJ. Short-Duration Therapeutic Hypothermia Causes Prompt Connexin43 Gap Junction Remodeling in Isolated Rabbit Hearts. Circ J 2011; 75:1706-16. [DOI: 10.1253/circj.cj-10-1001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yu-Cheng Hsieh
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
| | - Hung-I Yeh
- Departments of Medical Research and Internal Medicine, Mackay Memorial Hospital, Mackay Medical College
| | - Shien-Fong Lin
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine
| | - Ya-Wen Hsu
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
| | - Jin-Long Huang
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
- School of Medicine, Chung-Shan Medical University
| | - Tung-Chao Lin
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
| | - Chih-Tai Ting
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
| | - Tsu-Juey Wu
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine
- School of Medicine, Chung-Shan Medical University
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Takanari H, Honjo H, Takemoto Y, Suzuki T, Kato S, Harada M, Okuno Y, Ashihara T, Opthof T, Sakuma I, Kamiya K, Kodama I. Bepridil facilitates early termination of spiral-wave reentry in two-dimensional cardiac muscle through an increase of intercellular electrical coupling. J Pharmacol Sci 2010; 115:15-26. [PMID: 21157118 DOI: 10.1254/jphs.10233fp] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Bepridil is effective for conversion of atrial fibrillation to sinus rhythm and in the treatment of drug-refractory ventricular tachyarrhythmias. We investigated the effects of bepridil on electrophysiological properties and spiral-wave (SW) reentry in a 2-dimensional ventricular muscle layer of isolated rabbit hearts by optical mapping. Ventricular tachycardia (VT) induced in the presence of bepridil (1 µM) terminated earlier than in the control. Bepridil increased action potential duration (APD) by 5% - 8% under constant pacing and significantly increased the space constant. There was a linear relationship between the wavefront curvature (κ) and local conduction velocity: LCV = LCV₀ - D·κ (D, diffusion coefficient; LCV₀, LCV at κ = 0). Bepridil significantly increased D and LCV₀. The regression lines with and without bepridil crossed at κ = 20 - 40 cm⁻¹, resulting in a paradoxical decrease of LCV at κ > 40 cm⁻¹. Dye transfer assay in cultured rat cardiomyocytes confirmed that bepridil increased intercellular coupling. SW reentry in the presence of bepridil was characterized by decremental conduction near the rotation center, prominent drift, and self-termination by collision with boundaries. These results indicate that bepridil causes an increase of intercellular coupling and a moderate APD prolongation, and this combination compromises wavefront propagation near the rotation center of SW reentry, leading to its drift and early termination.
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Affiliation(s)
- Hiroki Takanari
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Japan
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Mirzoyev SA, McLeod CJ, Bunch TJ, Bell MR, White RD. Hypokalemia during the cooling phase of therapeutic hypothermia and its impact on arrhythmogenesis. Resuscitation 2010; 81:1632-6. [PMID: 20828913 DOI: 10.1016/j.resuscitation.2010.08.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 07/26/2010] [Accepted: 08/06/2010] [Indexed: 11/28/2022]
Abstract
BACKGROUND Mild to moderate therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) as the presenting rhythm. This approach entails the management of physiological variables which fall outside the realm of conventional critical cardiac care. Management of serum potassium fluxes remains pivotal in the avoidance of lethal ventricular arrhythmia. METHODS We retrospectively analyzed potassium variability with TH and performed correlative analysis of QT intervals and the incidence of ventricular arrhythmia. RESULTS We enrolled 94 sequential patients with OHCA, and serum potassium was followed intensively. The average initial potassium value was 3.9±0.7 mmol l(-1) and decreased to a nadir of 3.2±0.7 mmol l(-1) at 10 h after initiation of cooling (p<0.001). Eleven patients developed sustained polymorphic ventricular tachycardia (PVT) with eight of these occurring during the cooling phase. The corrected QT interval prolonged in relation to the development of hypothermia (p<0.001). Hypokalemia was significantly associated with the development of PVT (p=0.002), with this arrhythmia being most likely to develop in patients with serum potassium values of less than 2.5 mmol l(-1) (p=0.002). Rebound hyperkalemia did not reach concerning levels (maximum 4.26±0.8 mmol l(-1) at 40 h) and was not associated with the occurrence of ventricular arrhythmia. Furthermore, repletion of serum potassium did not correlate with the development of ventricular arrhythmia. CONCLUSIONS Therapeutic hypothermia is associated with a significant decline in serum potassium during cooling. Hypothermic core temperatures do not appear to protect against ventricular arrhythmia in the context of severe hypokalemia and cautious supplementation to maintain potassium at 3.0 mmol l(-1) appears to be both safe and effective.
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Affiliation(s)
- Sultan A Mirzoyev
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905, United States
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Nakagawa H, Honjo H, Ishiguro YS, Yamazaki M, Okuno Y, Harada M, Takanari H, Sakuma I, Kamiya K, Kodama I. Acute amiodarone promotes drift and early termination of spiral wave re-entry. Heart Vessels 2010; 25:338-47. [PMID: 20676844 DOI: 10.1007/s00380-009-1184-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Accepted: 07/09/2009] [Indexed: 11/25/2022]
Abstract
Intravenous application of amiodarone is commonly used in the treatment of life-threatening arrhythmias, but the underlying mechanism is not fully understood. The purpose of the present study is to investigate the acute effects of amiodarone on spiral wave (SW) re-entry, the primary organization machinery of ventricular tachycardia/fibrillation (VT/VF), in comparison with lidocaine. A two-dimensional ventricular myocardial layer was obtained from 24 Langendorff-perfused rabbit hearts, and epicardial excitations were analyzed by high-resolution optical mapping. During basic stimulation, amiodarone (5 microM) caused prolongation of action potential duration (APD) by 5.6%-9.1%, whereas lidocaine (15 microM) caused APD shortening by 5.0%-6.4%. Amiodarone and lidocaine reduced conduction velocity similarly. Ventricular tachycardias induced by DC stimulation in the presence of amiodarone were of shorter duration (sustained-VTs >30 s/total VTs: 2/58, amiodarone vs 13/52, control), whereas those with lidocaine were of longer duration (22/73, lidocaine vs 14/58, control). Amiodarone caused prolongation of VT cycle length and destabilization of SW re-entry, which is characterized by marked prolongation of functional block lines, frequent wavefront-tail interactions near the rotation center, and considerable drift, leading to its early annihilation via collision with anatomical boundaries. Spiral wave re-entry in the presence of lidocaine was more stabilized than in control. In the anisotropic ventricular myocardium, amiodarone destabilizes SW re-entry facilitating its early termination. Lidocaine, in contrast, stabilizes SW re-entry resulting in its persistence.
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Affiliation(s)
- Harumichi Nakagawa
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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Matsuda H, Kurata Y, Oka C, Matsuoka S, Noma A. Magnesium gating of cardiac gap junction channels. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:102-10. [PMID: 20553744 DOI: 10.1016/j.pbiomolbio.2010.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 02/26/2010] [Accepted: 05/19/2010] [Indexed: 01/18/2023]
Abstract
We aimed to study kinetics of modulation by intracellular Mg(2+) of cardiac gap junction (Mg(2+) gate). Paired myocytes of guinea-pig ventricle were superfused with solutions containing various concentrations of Mg(2+). In order to rapidly apply Mg(2+) to one aspect of the gap junction, the non-junctional membrane of one of the pair was perforated at nearly the connecting site by pulses of nitrogen laser beam. The gap junction conductance (G(j)) was measured by clamping the membrane potential of the other cell using two-electrode voltage clamp method. The laser perforation immediately increased G(j), followed by slow G(j) change with time constant of 3.5 s at 10 mM Mg(2+). Mg(2+) more than 1.0 mM attenuated dose-dependently the gap junction conductance and lower Mg(2+) (0.6 mM) increased G(j) with a Hill coefficient of 3.4 and a half-maximum effective concentration of 0.6 mM. The time course of G(j) changes was fitted by single exponential function, and the relationship between the reciprocal of time constant and Mg(2+) concentration was almost linear. Based on the experimental data, a mathematical model of Mg(2+) gate with one open state and three closed states well reproduced experimental results. One-dimensional cable model of thirty ventricular myocytes connected to the Mg(2+) gate model suggested a pivotal role of the Mg(2+) gate of gap junction under pathological conditions.
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Affiliation(s)
- Hiroyuki Matsuda
- Department of Physiology and Biophysics, Graduate School of Medicine, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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Hsieh YC, Lin SF, Lin TC, Ting CT, Wu TJ. Therapeutic hypothermia (30 degrees C) enhances arrhythmogenic substrates, including spatially discordant alternans, and facilitates pacing-induced ventricular fibrillation in isolated rabbit hearts. Circ J 2009; 73:2214-22. [PMID: 19789414 DOI: 10.1253/circj.cj-09-0432] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Therapeutic hypothermia (TH, 30 degrees C) protects the brain from hypoxic injury. However, TH may potentiate the occurrence of lethal ventricular fibrillation (VF), although the mechanism remains unclear. The present study explored the hypothesis that TH enhances wavebreaks during VF and S(1) pacing, facilitates pacing-induced spatially discordant alternans (SDA), and increases the vulnerability of pacing-induced VF. METHODS AND RESULTS Using an optical mapping system, epicardial activations of VF were studied in 7 Langendorff-perfused isolated rabbit hearts at baseline (37 degrees C), TH (30 degrees C), and rewarming (37 degrees C). Action potential duration (APD)/conduction velocity (CV) restitution and APD alternans (n=6 hearts) were determined by S(1) pacing at these 3 stages. During TH, there was a higher percentage of VF duration containing epicardial repetitive activities (spatiotemporal periodicity) (P<0.001). However, TH increased phase singularity number (wavebreaks) during VF (P<0.05) and S(1) pacing (P<0.05). TH resulted in earlier onset of APD alternans (P<0.001), which was predominantly SDA (P<0.05), and increased pacing-induced VF episodes (P<0.05). TH also decreased CV, shortened wavelength, and enhanced APD dispersion and the spatial heterogeneity of CV restitution. CONCLUSIONS TH (30 degrees C) increased the vulnerability of pacing-induced VF by (1)facilitating wavebreaks during VF and S(1) pacing, and (2)enhancing proarrhythmic electrophysiological parameters, including promoting earlier onset of APD alternans (predominantly SDA) during S(1) pacing.
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Affiliation(s)
- Yu-Cheng Hsieh
- Cardiovascular Center, Taichung Veterans General Hospital, Taichung and Department of Internal Medicine, Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
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Abstract
BACKGROUND Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood. OBJECTIVE To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects. DESIGN Review article. INTERVENTIONS None. MAIN RESULTS A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (<or=30 degrees C), moderate hypothermia does not induce arrhythmias; indeed, the evidence suggests that arrhythmias can be prevented and/or more easily treated under hypothermic conditions. CONCLUSIONS Therapeutic hypothermia is a highly promising treatment, but the potential side effects need to be properly managed particularly if prolonged treatment periods are required. Understanding the underlying mechanisms, awareness of physiological changes associated with cooling, and prevention of potential side effects are all key factors for its effective clinical usage.
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Therapeutic hypothermia and controlled normothermia in the intensive care unit: practical considerations, side effects, and cooling methods. Crit Care Med 2009; 37:1101-20. [PMID: 19237924 DOI: 10.1097/ccm.0b013e3181962ad5] [Citation(s) in RCA: 466] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Hypothermia is being used with increasing frequency to prevent or mitigate various types of neurologic injury. In addition, symptomatic fever control is becoming an increasingly accepted goal of therapy in patients with neurocritical illness. However, effectively controlling fever and inducing hypothermia poses special challenges to the intensive care unit team and others involved in the care of critically ill patients. OBJECTIVE To discuss practical aspects and pitfalls of therapeutic temperature management in critically ill patients, and to review the currently available cooling methods. DESIGN Review article. INTERVENTIONS None. MAIN RESULTS Cooling can be divided into three distinct phases: induction, maintenance, and rewarming. Each has its own risks and management problems. A number of cooling devices that have reached the market in recent years enable reliable maintenance and slow and controlled rewarming. In the induction phase, rapid cooling rates can be achieved by combining cold fluid infusion (1500-3000 mL 4 degrees C saline or Ringer's lactate) with an invasive or surface cooling device. Rapid induction decreases the risks and consequences of short-term side effects, such as shivering and metabolic disorders. Cardiovascular effects include bradycardia and a rise in blood pressure. Hypothermia's effect on myocardial contractility is variable (depending on heart rate and filling pressure); in most patients myocardial contractility will increase, although mild diastolic dysfunction can develop in some patients. A risk of clinically significant arrhythmias occurs only if core temperature decreases below 30 degrees C. The most important long-term side effects of hypothermia are infections (usually of the respiratory tract or wounds) and bedsores. CONCLUSIONS Temperature management and hypothermia induction are gaining importance in critical care medicine. Intensive care unit physicians, critical care nurses, and others (emergency physicians, neurologists, and cardiologists) should be familiar with the physiologic effects, current indications, techniques, complications and practical issues of temperature management, and induced hypothermia. In experienced hands the technique is safe and highly effective.
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Ishiguro YS, Honjo H, Opthof T, Okuno Y, Nakagawa H, Yamazaki M, Harada M, Takanari H, Suzuki T, Morishima M, Sakuma I, Kamiya K, Kodama I. Early termination of spiral wave reentry by combined blockade of Na+ and L-type Ca2+ currents in a perfused two-dimensional epicardial layer of rabbit ventricular myocardium. Heart Rhythm 2009; 6:684-92. [PMID: 19303369 DOI: 10.1016/j.hrthm.2009.01.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2008] [Accepted: 01/17/2009] [Indexed: 11/25/2022]
Abstract
BACKGROUND Modification of spiral wave (SW) reentry by antiarrhythmic drugs is a central issue to be challenged for better understanding of their benefits and risks. OBJECTIVE We investigated the effects of pilsicainide and/or verapamil, which block sodium and L-type calcium currents (I(Na) and I(Ca,L)), respectively, on SW reentry. METHODS A two-dimensional epicardial ventricular muscle layer was created in rabbit hearts by cryoablation (n = 32), and action potential signals were analyzed by high-resolution optical mapping. RESULTS During constant stimulation, pilsicainide (3-5 microM) caused a frequency-dependent decrease of conduction velocity (CV; by 20%-54% at 5 Hz) without affecting action potential duration (APD). Verapamil (3 microM) caused APD shortening (by 16% at 5 Hz) without affecting CV. Ventricular tachycardias (VTs) that were induced were more sustained in the presence of either pilsicainide or verapamil. The incidence of sustained VTs (>30 s)/all VTs per heart was 58% +/- 9% for 5 microM pilsicainide vs. 22% +/- 9% for controls and 62% +/- 10% for 3 microM verapamil vs. 22% +/- 8% for controls. The SWs with pilsicainide were characterized by slower rotation around longer functional block lines (FBLs), whereas those with verapamil were characterized by faster rotation around shorter FBLs. Combined application of 3 microM pilsicainide and 3 microM verapamil resulted in early termination of VTs (sustained VTs/all VTs per heart: 2% +/- 2% vs. 29% +/- 9% for controls); SWs showed extensive drift and decremental conduction, leading to their spontaneous annihilation. CONCLUSION Blockade of either I(Na) or I(Ca,L) stabilizes SWs in a two-dimensional epicardial layer of rabbit ventricular myocardium to help their persistence, whereas blockade of both currents destabilizes SWs to facilitate their termination.
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Affiliation(s)
- Yuko S Ishiguro
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
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