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Călburean PA, Pannone L, Sorgente A, Gauthey A, Monaco C, Strazdas A, Almorad A, Bisignani A, Bala G, Ramak R, Overeinder I, Ströker E, Pappaert G, Van Dooren S, de Ravel T, La Meir M, Brugada P, Sieira J, Chierchia GB, de Asmundis C. Heart rate variability and microvolt T wave alternans changes during ajmaline test may predict prognosis in Brugada syndrome. Clin Auton Res 2023; 33:51-62. [PMID: 36645559 DOI: 10.1007/s10286-023-00922-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/03/2023] [Indexed: 01/17/2023]
Abstract
PURPOSE Drug-induced type I Brugada syndrome (BrS) is associated with a ventricular arrhythmia (VA) rate of 1 case per 100 person-years. This study aims to evaluate changes in electrocardiographic (ECG) parameters such as microvolt T wave alternans (mTWA) and heart rate variability (HRV) at baseline and during ajmaline testing for BrS diagnosis. METHODS Consecutive patients diagnosed with BrS during ajmaline testing with 5-year follow-up were included in this study. For comparison, a negative ajmaline control group and an isoproterenol control group were also included. ECG recordings during ajmaline or isoproterenol test were divided in two timeframes from which ECG parameters were calculated: a 5-min baseline timeframe and a 5-min drug timeframe. RESULTS A total of 308 patients with BrS were included, 22 (0.7%) of which suffered VAs during follow-up. One hundred patients were included in both isoproterenol and negative ajmaline control groups. At baseline, there was no difference in ECG parameters between control groups and patients with BrS, nor between BrS with and without VAs. During ajmaline testing, BrS with VAs presented longer QRS duration [159 ± 34 ms versus 138 (122-155) ms, p = 0.006], higher maximum mTWA [33.8 (14.0-114) µV versus 8.00 (3.67-28.2) µV, p = 0.001], and lower power in low frequency band [25.6 (5.8-53.8) ms2 versus 129.5 (52.7-286) ms2, p < 0.0001] when compared to BrS without VAs. CONCLUSIONS Ajmaline induced important HRV changes similar to those observed during isoproterenol. Increased mTWA was observed only in patients with BrS. BrS with VAs during follow-up presented worse changes during ajmaline test, including lower LF power and higher maximum mTWA which were independent predictors of events.
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Affiliation(s)
- Paul-Adrian Călburean
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium.,George Emil Palade University of Medicine, Pharmacy, Science and Technology of Targu Mures, Targu Mures, Romania
| | - Luigi Pannone
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Antonio Sorgente
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Anaïs Gauthey
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Cinzia Monaco
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Antanas Strazdas
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Alexandre Almorad
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Antonio Bisignani
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Gezim Bala
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Robbert Ramak
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Ingrid Overeinder
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Erwin Ströker
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Gudrun Pappaert
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Sonia Van Dooren
- Genetics Department, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, Brussels, Belgium
| | - Thomy de Ravel
- Genetics Department, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, Brussels, Belgium
| | - Mark La Meir
- Cardiac Surgery Department, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Brussels, Belgium
| | - Pedro Brugada
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Juan Sieira
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Gian-Battista Chierchia
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Carlo de Asmundis
- Heart Rhythm Management Centre, Postgraduate Program in Cardiac Electrophysiology and Pacing, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, European Reference Networks Guard-Heart, Laarbeeklaan 101, 1090, Brussels, Belgium.
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Millet J, Aguilar-Sanchez Y, Kornyeyev D, Bazmi M, Fainstein D, Copello JA, Escobar AL. Thermal modulation of epicardial Ca2+ dynamics uncovers molecular mechanisms of Ca2+ alternans. J Gen Physiol 2021; 153:211659. [PMID: 33410862 PMCID: PMC7797898 DOI: 10.1085/jgp.202012568] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 11/02/2020] [Accepted: 11/30/2020] [Indexed: 01/16/2023] Open
Abstract
Ca2+ alternans (Ca-Alts) are alternating beat-to-beat changes in the amplitude of Ca2+ transients that frequently occur during tachycardia, ischemia, or hypothermia that can lead to sudden cardiac death. Ca-Alts appear to result from a variation in the amount of Ca2+ released from the sarcoplasmic reticulum (SR) between two consecutive heartbeats. This variable Ca2+ release has been attributed to the alternation of the action potential duration, delay in the recovery from inactivation of RYR Ca2+ release channel (RYR2), or an incomplete Ca2+ refilling of the SR. In all three cases, the RYR2 mobilizes less Ca2+ from the SR in an alternating manner, thereby generating an alternating profile of the Ca2+ transients. We used a new experimental approach, fluorescence local field optical mapping (FLOM), to record at the epicardial layer of an intact heart with subcellular resolution. In conjunction with a local cold finger, a series of images were recorded within an area where the local cooling induced a temperature gradient. Ca-Alts were larger in colder regions and occurred without changes in action potential duration. Analysis of the change in the enthalpy and Q10 of several kinetic processes defining intracellular Ca2+ dynamics indicated that the effects of temperature change on the relaxation of intracellular Ca2+ transients involved both passive and active mechanisms. The steep temperature dependency of Ca-Alts during tachycardia suggests Ca-Alts are generated by insufficient SERCA-mediated Ca2+ uptake into the SR. We found that Ca-Alts are heavily dependent on intra-SR Ca2+ and can be promoted through partial pharmacologic inhibition of SERCA2a. Finally, the FLOM experimental approach has the potential to help us understand how arrhythmogenesis correlates with the spatial distribution of metabolically impaired myocytes along the myocardium.
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Affiliation(s)
- Jose Millet
- Institute of Information and Communication Technologies, Universitat Politècnica de València and Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Valencia, Spain
| | - Yuriana Aguilar-Sanchez
- Department of Physiology and Biophysics, School of Medicine, Rush University Medical Center, Chicago, IL.,School of Natural Sciences, University of California, Merced, Merced, CA
| | - Dmytro Kornyeyev
- Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
| | - Maedeh Bazmi
- School of Natural Sciences, University of California, Merced, Merced, CA
| | - Diego Fainstein
- Facultad de Ingeniería, Universidad Nacional de Entre Ríos, Entre Ríos, Argentina.,Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
| | - Julio A Copello
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL
| | - Ariel L Escobar
- Department of Bioengineering, School of Engineering, University of California Merced, Merced, CA
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Bhuiyan TA, Graff C, Kanters JK, Melgaard J, Toft E, Kääb S, Struijk JJ. A History of Drug‐Induced Torsades de Pointes Is Associated With T‐wave Morphological Abnormalities. Clin Pharmacol Ther 2017; 103:1100-1106. [DOI: 10.1002/cpt.886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/07/2017] [Accepted: 09/14/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Tanveer A. Bhuiyan
- Department of Health Science and TechnologyAalborg UniversityAalborg Denmark
| | - Claus Graff
- Department of Health Science and TechnologyAalborg UniversityAalborg Denmark
| | - Jørgen K. Kanters
- Laboratory of Experimental Cardiology, Department of Biomedical SciencesUniversity of CopenhagenCopenhagen Denmark
| | - Jacob Melgaard
- Department of Health Science and TechnologyAalborg UniversityAalborg Denmark
| | - Egon Toft
- College of Medicine, Qatar UniversityDoha Qatar
| | - Stefan Kääb
- Medizinische Klinik und Poliklinik I, University Hospital Munich, Ludvig Maximilians University, Munich, Germany; German Center for Cardiovascular Research (DZHK), partner site: Munich Heart AllianceMunich Germany
| | - Johannes J. Struijk
- Department of Health Science and TechnologyAalborg UniversityAalborg Denmark
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The T-peak–T-end Interval as a Marker of Repolarization Abnormality: A Comparison with the QT Interval for Five Different Drugs. Clin Drug Investig 2015; 35:717-24. [DOI: 10.1007/s40261-015-0328-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Takei K, Honda W, Harada S, Arie T, Akita S. Toward flexible and wearable human-interactive health-monitoring devices. Adv Healthc Mater 2015; 4:487-500. [PMID: 25425072 DOI: 10.1002/adhm.201400546] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 10/25/2014] [Indexed: 01/08/2023]
Abstract
This Progress Report introduces flexible wearable health-monitoring devices that interact with a person by detecting from and stimulating the body. Interactive health-monitoring devices should be highly flexible and attach to the body without awareness like a bandage. This type of wearable health-monitoring device will realize a new class of electronics, which will be applicable not only to health monitoring, but also to other electrical devices. However, to realize wearable health-monitoring devices, many obstacles must be overcome to economically form the active electrical components on a flexible substrate using macroscale fabrication processes. In particular, health-monitoring sensors and curing functions need to be integrated. Here recent developments and advancements toward flexible health-monitoring devices are presented, including conceptual designs of human-interactive devices.
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Affiliation(s)
- Kuniharu Takei
- Department of Physics and Electronics; Osaka Prefecture University; Sakai Osaka 599-8531 Japan
| | - Wataru Honda
- Department of Physics and Electronics; Osaka Prefecture University; Sakai Osaka 599-8531 Japan
| | - Shingo Harada
- Department of Physics and Electronics; Osaka Prefecture University; Sakai Osaka 599-8531 Japan
| | - Takayuki Arie
- Department of Physics and Electronics; Osaka Prefecture University; Sakai Osaka 599-8531 Japan
| | - Seiji Akita
- Department of Physics and Electronics; Osaka Prefecture University; Sakai Osaka 599-8531 Japan
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Mitsuyama H, Yokoshiki H, Watanabe M, Mizukami K, Shimokawa J, Tsutsui H. Ca2+/calmodulin-dependent protein kinase II increases the susceptibility to the arrhythmogenic action potential alternans in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2014; 307:H199-206. [DOI: 10.1152/ajpheart.00387.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Action potential duration alternans (APD-ALT), defined as long-short-long repetitive pattern of APD, potentially leads to lethal ventricular arrhythmia. However, the mechanisms of APD-ALT in the arrhythmogenesis of cardiac hypertrophy remain undetermined. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is known to modulate the function of cardiac sarcoplasmic reticulum and play an important role in Ca2+ cycling. We thus aimed to determine the role of CaMKII in the increased susceptibility to APD-ALT and arrhythmogenesis in the hypertrophied heart. APD was measured by high-resolution optical mapping in left ventricular (LV) anterior wall from normotensive Wistar-Kyoto (WKY; n = 10) and spontaneously hypertensive rats (SHR; n = 10) during rapid ventricular pacing. APD-ALT was evoked at significantly lower pacing rate in SHR compared with WKY (382 ± 43 vs. 465 ± 45 beats/min, P < 0.01). These changes in APD-ALT in SHR were completely reversed by KN-93 (1 μmol/l; n = 5), an inhibitor of CaMKII, but not its inactive analog, KN-92 (1 μmol/l; n = 5). The magnitude of APD-ALT was also significantly greater in SHR than WKY and was completely normalized by KN-93. Ventricular fibrillation (VF) was induced by rapid pacing more frequently in SHR than in WKY (60 vs. 10%; P < 0.05), which was also abolished by KN-93 (0%, P < 0.05). Western blot analyses indicated that the CaMKII autophosphorylation at Thr287 was significantly increased in SHR compared with WKY. The increased susceptibility to APD-ALT and VF during rapid pacing in hypertrophied heart was prevented by KN-93. CaMKII could be an important mechanism of arrhythmogenesis in cardiac hypertrophy.
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Affiliation(s)
- Hirofumi Mitsuyama
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hisashi Yokoshiki
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masaya Watanabe
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Kazuya Mizukami
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Junichi Shimokawa
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hiroyuki Tsutsui
- Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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7
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Bakhshi A, Bashir S, Maud M. An improved statistical representation for ECG electrode movement and muscular activity noises in the context of T-wave alternan estimation. Biomed Signal Process Control 2013. [DOI: 10.1016/j.bspc.2012.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Calsequestrin 2 deletion shortens the refractoriness of Ca²⁺ release and reduces rate-dependent Ca²⁺-alternans in intact mouse hearts. J Mol Cell Cardiol 2011; 52:21-31. [PMID: 21983287 DOI: 10.1016/j.yjmcc.2011.09.020] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 09/18/2011] [Accepted: 09/20/2011] [Indexed: 11/24/2022]
Abstract
Calsequestrin (Casq2) is a low affinity Ca(2+)-binding protein located in sarcoplasmic reticulum (SR) of cardiac myocytes. Casq2 acts as a Ca(2+) buffer regulating free Ca(2+) concentration in the SR lumen and plays a significant role in the regulation of Ca(2+) release from this intracellular organelle. In addition, there is experimental evidence supporting the hypothesis that Casq2 also modulates the activity of the cardiac Ca(2+) release channels, ryanodine receptors (RyR2). In this study, Casq2 knockout mice (Casq2-/-) were used as a model to evaluate the effects of the Casq2 on the cytosolic and intra-SR Ca(2+) dynamics, and the electrical activity in the ventricular epicardial layer of intact beating hearts. Casq2-/- mice have accelerated intra-SR Ca(2+) refilling kinetics (76 ± 22 vs. 136.5 ± 15 ms) and a reduced refractoriness of Ca(2+) release (182 ± 32 ms Casq2+/+ and 111 ± 22 ms Casq2-/- ). In addition, mice display reduced Ca(2+) alternans (67% decline in the amplitude of Ca(2+) alternans at 7 Hz, 21oC) and less T-wave alternans at the electrocardiographic level. The results presented in this paper support the idea of Casq2 acting both as a buffer and a direct regulator of the Ca(2+) release process. Finally, we propose that alterations in Ca(2+) release refractoriness shown here could explain the relationship between Casq2 function and an increase in the risk for ventricular arrhythmias.
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Lopera G, Curtis AB. Risk stratification for sudden cardiac death: current approaches and predictive value. Curr Cardiol Rev 2011; 5:56-64. [PMID: 20066150 PMCID: PMC2803290 DOI: 10.2174/157340309787048130] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 07/05/2008] [Accepted: 07/05/2008] [Indexed: 11/22/2022] Open
Abstract
Sudden cardiac death (SCD) is a serious public health problem; the annual incidence of out-of-hospital cardiac arrest in North America is approximately 166,200. Identifying patients at risk is a difficult proposition. At the present time, left ventricular ejection fraction (LVEF) remains the single most important marker for risk stratification. According to current guidelines, most patients with LVEF <35% could benefit from prophylactic ICD implantation, particularly in the setting of symptomatic heart failure. Current risk stratification strategies fail to identify patients at risk of SCD in larger population groups encompassing a greater number of potential SCD victims. However, the best approach to identifying patients and the value of various risk stratification tools is not entirely clear. The goal of this review is to discuss the problem of SCD and the value of the different risk stratification markers and their potential clinical use either alone or in combination with other risk stratification markers.
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Affiliation(s)
- Gustavo Lopera
- Division of Cardiology, University of Miami/Miller School of Medicine, Miami, FL, USA
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Weinberg S, Malhotra N, Tung L. Vulnerable windows define susceptibility to alternans and spatial discordance. Am J Physiol Heart Circ Physiol 2010; 298:H1727-37. [PMID: 20363894 PMCID: PMC2886623 DOI: 10.1152/ajpheart.01036.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 03/29/2010] [Indexed: 11/22/2022]
Abstract
Electrophysiological alternans is a beat-to-beat alternation of the action potential duration and/or Ca(2+) transient amplitude and is linked to ventricular arrhythmias. We investigated the significance of various rate parameters under different experimental conditions with respect to alternans incidence and the propensity for spiral wave formation. Voltage and Ca(2+) were optically mapped in monolayers of neonatal rat ventricular myocytes. Alternans did not occur at physiological temperature, but its incidence increased significantly at lowered temperatures. Pacing cycle length for spatially concordant alternans onset (PCL(C)), PCL for spatially discordant alternans onset (PCL(D)), and minimum cycle length for loss of 1:1 or 2:2 capture (MCL) also significantly increased with lower temperature but in a way such that the differences between PCL(C) and MCL and between PCL(D) and MCL widened. These results provided the rationale to identify the former difference as the alternans vulnerable window (AVW; in ms) and the latter difference as the discordant alternans vulnerable window (AVW(D); in ms). Computational simulations showed that interventions that widen AVW, including altered Ca(2+) cycling and enhanced K(+) currents, also promote alternans, regardless of whether PCL(C) or MCL increased or decreased. The simulation results were confirmed experimentally by addition of the ATP-sensitive K(+) channel agonist pinacidil. Mathematical analysis provided a theoretical basis linking the size of AVW to the incidence of alternans. Finally, experiments showed that the size of AVW(D) is related to the incidence of spatially discordant alternans and, additionally, to the incidence of spiral wave formation. In conclusion, vulnerable windows can be defined that are strongly correlated with alternans incidence, spatial discordance, and spiral wave formation.
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Affiliation(s)
- Seth Weinberg
- Department of Biomedical Engineering, The Johns Hopkins Univ. 720 Rutland Ave., Baltimore, MD 21205, USA
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Kornyeyev D, Reyes M, Escobar AL. Luminal Ca(2+) content regulates intracellular Ca(2+) release in subepicardial myocytes of intact beating mouse hearts: effect of exogenous buffers. Am J Physiol Heart Circ Physiol 2010; 298:H2138-53. [PMID: 20382849 DOI: 10.1152/ajpheart.00885.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(+)-induced Ca(2+) release tightly controls the function of ventricular cardiac myocytes under normal and pathological conditions. Two major factors contributing to the regulation of Ca(2+) release are the cytosolic free Ca(2+) concentration and sarcoplasmic reticulum (SR) Ca(2+) content. We hypothesized that the amount of Ca(2+) released from the SR during each heart beat strongly defines the refractoriness of Ca(2+) release. To test this hypothesis, EGTA AM, a high-affinity, slow-association rate Ca(2+) chelator, was used as a tool to modify luminal SR Ca(2+) content. An analysis of the cytosolic and luminal SR Ca(2+) dynamics recorded from the epicardial layer of intact mouse hearts indicated that the presence of EGTA reduced the diastolic SR free Ca(2+) concentration and fraction of SR Ca(2+) depletion during each beat. In addition, this maneuver shortened the refractory period and accelerated the restitution of Ca(2+) release. As a consequence of the accelerated restitution, the frequency dependence of Ca(2+) alternans was significantly shifted toward higher heart rates, suggesting a role of luminal SR Ca(2+) in the genesis of this highly arrhythmogenic phenomenon. Thus, intra-SR Ca(2+) dynamics set the refractoriness and frequency dependence of Ca(2+) transients in subepicardial ventricular myocytes.
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Affiliation(s)
- Dmytro Kornyeyev
- School of Engineering, Univ. of California-Merced, 5200 N. Lake Rd., Merced, CA 95343, USA
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12
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Puntmann VO, Yap YG, McKenna W, Camm J. T-Wave Alternans and Left Ventricular Wall Thickness in Predicting Arrhythmic Risk in Patients With Hypertrophic Cardiomyopathy. Circ J 2010; 74:1197-204. [DOI: 10.1253/circj.cj-09-1003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Jia Z, Bien H, Entcheva E. Detecting space-time alternating biological signals close to the bifurcation point. IEEE Trans Biomed Eng 2009; 57:316-24. [PMID: 19695992 DOI: 10.1109/tbme.2009.2028652] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Time-alternating biological signals, i.e., alternans, arise in variety of physiological states marked by dynamic instabilities, e.g., period doubling. Normally, a sequence of large-small-large transients, they can exhibit variable patterns over time and space, including spatial discordance. Capture of the early formation of such alternating regions is challenging because of the spatiotemporal similarities between noise and the small-amplitude alternating signals close to the bifurcation point. We present a new approach for automatic detection of alternating signals in large noisy spatiotemporal datasets by exploiting quantitative measures of alternans evolution, e.g., temporal persistence, and by preserving phase information. The technique specifically targets low amplitude, relatively short alternating sequences and is validated by combinatorics-derived probabilities and empirical datasets with white noise. Using high-resolution optical mapping in live cardiomyocyte networks, exhibiting calcium alternans, we reveal for the first time early fine-scale alternans, close to the noise level, which are linked to the later formation of larger regions and evolution of spatially discordant alternans. This robust method aims at quantification and better understanding of the onset of cardiac arrhythmias and can be applied to general analysis of space-time alternating signals, including the vicinity of the bifurcation point.
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Affiliation(s)
- Zhiheng Jia
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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Jia Z, Bien H, Entcheva E. A sensitive algorithm for automatic detection of space-time alternating signals in cardiac tissue. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:153-6. [PMID: 19162616 DOI: 10.1109/iembs.2008.4649113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Alternans, a beat-to-beat alternation in cardiac signals, may serve as a precursor to lethal cardiac arrhythmias, including ventricular tachycardia and ventricular fibrillation. Therefore, alternans is a desirable target of early arrhythmia prediction/detection. For long-term records and in the presence of noise, the definition of alternans is qualitative and ambiguous. This makes their automatic detection in large spatiotemporal data sets almost impossible. We present here a quantitative combinatorics-derived definition of alternans in the presence of random noise and a novel algorithm for automatic alternans detection using criteria like temporal persistence (TP), representative phase (RP) and alternans ratio (AR). This technique is validated by comparison to theoretically-derived probabilities and by test data sets with white noise. Finally, the algorithm is applied to ultra-high resolution optical mapping data from cultured cell monolayers, exhibiting calcium alternans. Early fine-scale alternans, close to the noise level, were revealed and linked to the later formation of larger regions and evolution of spatially discordant alternans (SDA). This robust new technique can be useful in quantification and better understanding of the onset of arrhythmias and in general analysis of space-time alternating signals.
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Affiliation(s)
- Zhiheng Jia
- Biomedical Engineering department, Stony Brook University, Stony Brook, NY 11794, USA.
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Jin H, Lyon AR, Akar FG. Arrhythmia mechanisms in the failing heart. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2008; 31:1048-56. [PMID: 18684263 DOI: 10.1111/j.1540-8159.2008.01134.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Heart failure (HF) claims over 200,000 lives annually in the United States alone. Approximately 50% of these deaths are sudden and unexpected, and presumably the consequence of lethal ventricular tachyarrhythmias. Electrical remodeling that occurs at the cellular and tissue network levels predisposes patients with HF to malignant arrhythmias. Our limited understanding of fundamental arrhythmia mechanisms has hampered the development of effective treatment strategies for these patients. METHODS AND CONCLUSIONS In this review, we outline recent advances in our understanding of arrhythmia mechanisms in the failing heart, highlighting various aspects of remodeling of ion channels, calcium handling proteins, and gap junction-related molecules. As will be discussed, these changes promote the prolongation of the action potential, the enhancement of spatio-temporal gradients of repolarization, the formation of calcium-mediated triggers and conduction abnormalities, all of which combine to form an electrophysiological substrate that is ripe for the genesis of lethal arrhythmias and sudden cardiac death.
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Affiliation(s)
- Hongwei Jin
- Division of Cardiology, Cardiovascular Research Center, Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, USA
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Ventricular arrhythmias and changes in heart rate preceding ventricular tachycardia in patients with an implantable cardioverter defibrillator. Med Biol Eng Comput 2008; 46:715-27. [DOI: 10.1007/s11517-008-0326-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 02/19/2008] [Indexed: 11/26/2022]
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Inama G, Pedrinazzi C, Durin O, Nanetti M, Donato G, Pizzi R. Ventricular Arrhythmias in Competitive Athletes: Risk Stratification with T-Wave Alternans. Heart Int 2007. [DOI: 10.1177/1826186807003001-208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Giuseppe Inama
- Department of Cardiology, Ospedale Maggiore, Crema - Italy
| | | | - Ornella Durin
- Department of Cardiology, Ospedale Maggiore, Crema - Italy
| | | | - Giorgio Donato
- Department of Cardiology, Ospedale Maggiore, Crema - Italy
| | - Rita Pizzi
- Department of Information Technologies, University of Milan, Milan - Italy
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Inama G, Pedrinazzi C, Durin O, Nanetti M, Donato G, Pizzi R. Ventricular arrhythmias in competitive athletes: risk stratification with T-wave alternans. Heart Int 2007; 3:58. [PMID: 21977276 PMCID: PMC3184678 DOI: 10.4081/hi.2007.58] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Introduction: Aim of our study is to evaluate the role of TWA to stratify the risk of sudden cardiac death in athletes (Ath) with complex ventricular arrhythmias (VA), and to document a possible correlation between TWA and electrophysiological testing (EES) results. Methods: We studied 43 Ath with VA (31 M, mean age 34 ± 12 years). In all cases a cardiological evaluation was performed, including TWA and EES. The patients were evaluated during a follow-up of 25 ± 22 months. The end-point was the occurrence of sudden death or malignant ventricular tachyarrhythmias (VT). Results: TWA was negative in 28 Ath (65%), positive in 8 (19%) and indeterminate in 7 (16%). All subjects with negative TWA did not show induction of VT at EES, with significant correlation between negative TWA and negative EES (p<0.001). All Ath with positive TWA also had VT induced by a EES, but without significant correlation between positive TWA and positive EES. In 2 Ath with undetermined TWA (29%) VT were induced at EES. Our data did not show significant correlation between indeterminate TWA and positive or negative EES. However, logistic regression analysis showed significant correlation between abnormal TWA test (positive or indeterminate) and inducibility of VT at EES (p<0.001). During follow-up we observed a significant difference in end-point occurrence between Ath with negative or positive TWA and between Ath with negative or positive EES. Conclusion: TWA confirm its role as a simple and non-invasive test, and it seems useful for prognostic stratification of Ath with VA.
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Affiliation(s)
- Giuseppe Inama
- Department of Cardiology, Ospedale Maggiore, Crema - Italy
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Coutu P, Chartier D, Nattel S. Comparison of Ca2+-handling properties of canine pulmonary vein and left atrial cardiomyocytes. Am J Physiol Heart Circ Physiol 2006; 291:H2290-300. [PMID: 16798822 DOI: 10.1152/ajpheart.00730.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac tissue in the pulmonary vein sleeves plays an important role in clinical atrial fibrillation. Mechanisms leading to pulmonary vein activity in atrial fibrillation remain unclear. Indirect experimental evidence points to pulmonary vein Ca2+handling as a potential culprit, but there are no direct studies of pulmonary vein cardiomyocyte Ca2+handling in the literature. We used the Ca2+-sensitive dye indo-1 AM to study Ca2+handling in isolated canine pulmonary vein and left atrial myocytes. Results were obtained at 35°C and room temperature in cells from control dogs and in cardiomyocytes from dogs subjected to 7-day rapid atrial pacing. We found that basic Ca2+-transient properties (amplitude: 186 ± 28 vs. 216 ± 25 nM; stimulus to half-decay time: 192 ± 9 vs. 192 ± 9 ms; atria vs. pulmonary vein, respectively, at 1 Hz), beat-to-beat regularity, propensity to alternans, β-adrenergic response (amplitude increase at 0.4 Hz: 96 ± 52 vs. 129 ± 61%), number of spontaneous Ca2+-transient events after Ca2+loading (in normal Tyrode: 0.9 ± 0.2 vs. 1.3 ± 0.2; with 1 μM isoproterenol: 7.6 ± 0.3 vs. 5.1 ± 1.8 events/min), and caffeine-induced Ca2+-transient amplitudes were not significantly different between atrial and pulmonary vein cardiomyocytes. In an arrhythmia-promoting model (dogs subjected to 7-day atrial tachypacing), Ca2+-transient amplitude and kinetics were the same in cells from both pulmonary veins and atrium. In conclusion, the similar Ca2+-handling properties of canine pulmonary vein and left atrial cardiomyocytes that we observed do not support the hypothesis that intrinsic Ca2+-handling differences account for the role of pulmonary veins in atrial fibrillation.
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Affiliation(s)
- Pierre Coutu
- Research Center, Montreal Heart Institute, 5000 Belanger St. East, Montreal, Quebec, Canada
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Molon G, Targher G, Costa A, Bertolini L, Barbieri E, Zenari L. Measurement of microvolt T-wave alternans, a new arrhythmic risk stratification test, in Type 2 diabetic patients without clinical cardiovascular disease. Diabet Med 2006; 23:207-10. [PMID: 16433721 DOI: 10.1111/j.1464-5491.2006.01799.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS Patients with a positive microvolt T-wave alternans (TWA) are at increased risk of ventricular arrhythmias and sudden cardiac death. Although Type 2 diabetes is associated with an increased risk of these events, there is a dearth of available data on measurements of TWA in people with Type 2 diabetes. METHODS We studied 43 Type 2 diabetic volunteers who were free of diagnosed cardiovascular disease (CVD). Microvolt TWA analysis was performed non-invasively using the CH 2000 system during submaximal exercise with the patients sitting on a bicycle ergometer. RESULTS TWA analysis was positive in 9 (21%) patients, negative in 32 (74.4%) and indeterminate in 2 (4.6%) subjects. TWA positive patients had significantly higher HbA(1c) levels than those with TWA negativity (8.1 +/- 0.9 vs. 7.2 +/- 0.8%, P < 0.01). Age, sex, BMI, blood pressure, lipids, 24-h heart rate variability, QTc interval duration, smoking history, diabetes duration and treatment, and microvascular complication status did not differ between the groups. In regression logistic analysis, HbA(1c) was the only significant predictor of TWA positivity (odds ratio 5.7, 95% CI 1.3-26, P = 0.023) after controlling for potential confounders. CONCLUSIONS These results suggest that in Type 2 diabetic patients without clinically manifest CVD, TWA positivity is common (approximately 20%) and is closely correlated with glycaemic control.
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Affiliation(s)
- G Molon
- Division of Cardiology, Sacro Cuore Hospital, Negrar (VR), Italy
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Bernus O, Zemlin CW, Zaritsky RM, Mironov SF, Pertsov AM. Alternating conduction in the ischaemic border zone as precursor of reentrant arrhythmias: a simulation study. Europace 2005; 7 Suppl 2:93-104. [PMID: 16102507 DOI: 10.1016/j.eupc.2005.03.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 03/02/2005] [Accepted: 05/03/2005] [Indexed: 11/24/2022] Open
Abstract
AIMS Here, we investigate the mechanisms underlying the onset of conduction-related arrhythmias in a three-dimensional (3D) computational model of acute regional ischaemia. METHODS Ischaemia was introduced by realistic gradients of potassium, pH, oxygen and electrical coupling in a 3D slab of ventricular tissue using the LRd model. We focused on a specific stage (10-15 min after occlusion) at which an intramural non-conductive ischaemic core (IC) surrounded by a border zone (BZ) has formed. RESULTS At pacing frequencies greater than 4.5 Hz, we observed narrow areas (0.5 mm wide) of 2:1 conduction blocks at the periphery of the IC. As the pacing frequency increased, the area of block widened to 9 mm and gave rise to reentry at the periphery of the BZ. Alternating conduction blocks produced discordant action potential duration (APD) alternans throughout the slab and T-wave alternans in pseudo-ECG. Slowing the recovery of the calcium current broadened the range of pacing frequencies at which blocks were observed. Hyperkalaemia alone was sufficient to induce the alternating blocks. CONCLUSION Computer modelling predicts that ischaemia-related arrhythmias are triggered by calcium-mediated alternating conduction blocks in the ischaemic border zone. Alternating conduction blocks lead to intramural reentry and APD alternans.
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Affiliation(s)
- Olivier Bernus
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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Martínez JP, Olmos S. Methodological principles of T wave alternans analysis: a unified framework. IEEE Trans Biomed Eng 2005; 52:599-613. [PMID: 15825862 DOI: 10.1109/tbme.2005.844025] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Visible T wave alternans (TWA) in the electrocardiogram (ECG) had been regarded as an infrequent phenomenon during the first 80 years of electrocardiography. Nevertheless, computerized analysis changed this perception. In the last two decades, a variety of techniques for automatic TWA analysis have been proposed. These techniques have allowed researchers to detect nonvisible TWA in a wide variety of clinical and experimental conditions. Such studies have recently shown that TWA is related to cardiac instability and increased arrhythmogenicity. Comparison of TWA analysis methods is a difficult task due to the diversity of approaches. In this paper, we propose a unified framework which holds the existing methods. In the light of this framework, the methodological principles of the published TWA analysis schemes are compared and discussed. This framework may have an important role to develop new approaches to this problem.
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Affiliation(s)
- Juan Pablo Martínez
- Communications Technology Group, Aragon Institute of Engineering Research, University of Zaragoza, Maria de Luna, 1, 50018 Zaragoza, Spain.
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