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Cardiac alternans

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https://www.readbyqxmd.com/read/28708197/risk-stratification-personalised-model-for-prediction-of-life-threatening-ventricular-tachyarrhythmias-in-patients-with-chronic-heart-failure
#1
Alexander Vladimirovich Frolov, Tatjana Gennadjevna Vaikhanskaya, Olga Petrovna Melnikova, Anatoly Pavlovich Vorobiev, Ludmila Michajlovna Guel
BACKGROUND: The development of prognostic factors of life-threatening ventricular tachyarrhythmias (VTA) and sudden cardiac death (SCD) continues to maintain its priority and relevance in cardiology. The development of a method of personalised prognosis based on multifactorial analysis of the risk factors associated with life-threatening heart rhythm disturbances is considered a key research and clinical task. AIM: To design a prognostic and mathematical model to define personalised risk for life-threatening VTA in patients with chronic heart failure (CHF)...
2017: Kardiologia Polska
https://www.readbyqxmd.com/read/28698617/loss-of-md1-exacerbates-pressure-overload-induced-left-ventricular-structural-and-electrical-remodelling
#2
Jianye Peng, Yu Liu, Xiaoju Xiong, Congxin Huang, Yang Mei, Zhiqiang Wang, Yanhong Tang, Jing Ye, Bin Kong, Wanli Liu, Teng Wang, He Huang
Myeloid differentiation protein 1 (MD1) has been implicated in numerous pathophysiological processes, including immune regulation, obesity, insulin resistance, and inflammation. However, the role of MD1 in cardiac remodelling remains incompletely understood. We used MD1-knockout (KO) mice and their wild-type littermates to determine the functional significance of MD1 in the regulation of aortic banding (AB)-induced left ventricular (LV) structural and electrical remodelling and its underlying mechanisms. After 4 weeks of AB, MD1-KO hearts showed substantial aggravation of LV hypertrophy, fibrosis, LV dilation and dysfunction, and electrical remodelling, which resulted in overt heart failure and increased electrophysiological instability...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28696268/personalizing-risk-stratification-for-sudden-death-in-dilated-cardiomyopathy-the-past-present-and-future
#3
REVIEW
Brian P Halliday, John G F Cleland, Jeffrey J Goldberger, Sanjay K Prasad
Results from the DANISH Study (Danish Study to Assess the Efficacy of ICDs in Patients With Non-Ischemic Systolic Heat Failure on Mortality) suggest that for many patients with dilated cardiomyopathy (DCM), implantable cardioverter-defibrillators do not increase longevity. Accurate identification of patients who are more likely to die of an arrhythmia and less likely to die of other causes is required to ensure improvement in outcomes and wise use of resources. Until now, left ventricular ejection fraction has been used as a key criterion for selecting patients with DCM for an implantable cardioverter-defibrillator for primary prevention purposes...
July 11, 2017: Circulation
https://www.readbyqxmd.com/read/28670363/verapamil-suppresses-cardiac-alternans-and-ventricular-arrhythmias-in-acute-myocardial-ischemia-via-ryanodine-receptor-inhibition
#4
Yu-Lei Deng, Jun-Yan Zhao, Ji-Hua Yao, Qiang Tang, Le Zhang, Hong-Lian Zhou, Cun-Tai Zhang, Jia-Gao Lv, Xiao-Qing Quan
T-wave alternans (TWA) is a potent arrhythmia substrate under the conditions of acute myocardial ischemia. Abnormal intracellular calcium cycling contributes to the genesis of cardiac alternans. Ryanodine receptor (RyR) is a pivotal Ca(2+) cycling protein central to Ca(2+) signaling in the heart. Here, we investigated the potential role of RyR in cardiac alternans and ventricular arrhythmias in acute myocardial ischemia. Transmembrane action potentials were simultaneously recorded from epicardium and endocardium together with a transmural ECG and isometric contraction force in the arterially perfused left ventricular wedge preparations...
2017: American Journal of Translational Research
https://www.readbyqxmd.com/read/28666575/alternans-in-atria-mechanisms-and-clinical-relevance
#5
REVIEW
Giedrius Kanaporis, Lothar A Blatter
Atrial fibrillation is the most common sustained arrhythmia and its prevalence is rapidly rising with the aging of the population. Cardiac alternans, defined as cyclic beat-to-beat alternations in contraction force, action potential (AP) duration and intracellular Ca(2+) release at constant stimulation rate, has been associated with the development of ventricular arrhythmias. Recent clinical data also provide strong evidence that alternans plays a central role in arrhythmogenesis in atria. The aim of this article is to review the mechanisms that are responsible for repolarization alternans and contribute to the transition from spatially concordant alternans to the more arrhythmogenic spatially discordant alternans in atria...
June 7, 2017: Medicina
https://www.readbyqxmd.com/read/28662005/camkii-activation-promotes-cardiac-electrical-remodeling-and-increases-the-susceptibility-to-arrhythmia-induction-in-high-fat-diet-fed-mice-with-hyperlipidemia-conditions
#6
Peng Zhong, Dajun Quan, Yan Huang, He Huang
BACKGROUND: Obesity/hyperlipidemia is closely related to both atrial and ventricular arrhythmias. CaMKII, a multifunctional serine/threonine kinase, has been involved in cardiac arrhythmias of different etiology. However, its role in obesity/hyperlipidemia-related cardiac arrhythmia is unexplored. The aim of the present study was to determine the involvement of CaMKII in the process. METHODS: Adult male APOE-/- mice were fed a high-fat diet (HFD), administrated with KN93 (10mg/kg/2d), a specific inhibitor of CaMKII...
July 4, 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28552120/benchmarking-of-a-t-wave-alternans-detection-method-based-on-empirical-mode-decomposition
#7
Manuel Blanco-Velasco, Rebeca Goya-Esteban, Fernando Cruz-Roldán, Arcadi García-Alberola, José Luis Rojo-Álvarez
BACKGROUND AND OBJECTIVE: T-wave alternans (TWA) is a fluctuation of the ST-T complex occurring on an every-other-beat basis of the surface electrocardiogram (ECG). It has been shown to be an informative risk stratifier for sudden cardiac death, though the lack of gold standard to benchmark detection methods has promoted the use of synthetic signals. This work proposes a novel signal model to study the performance of a TWA detection. Additionally, the methodological validation of a denoising technique based on empirical mode decomposition (EMD), which is used here along with the spectral method, is also tackled...
July 2017: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/28550171/%C3%AE-adrenergic-receptor-stimulation-inhibits-proarrhythmic-alternans-in-post-infarction-border-zone-cardiomyocytes-a-computational-analysis
#8
Jakub Tomek, Blanca Rodriguez, Gil Bub, Jordi Heijman
The border zone (BZ) of viable myocardium adjacent to an infarct undergoes extensive autonomic and electrical remodelling and is prone to repolarisation alternans-induced cardiac arrhythmias. BZ remodelling processes may promote or inhibit calcium and/or repolarisation alternans and may differentially affect ventricular arrhythmogenesis. Here, we employed a detailed computational model of the canine ventricular cardiomyocyte to study the determinants of alternans in the BZ and their regulation by β-adrenergic receptor (βAR) stimulation...
May 26, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28526702/t-wave-morphology-restitution-predicts-sudden-cardiac-death-in-patients-with-chronic-heart-failure
#9
Julia Ramírez, Michele Orini, Ana Mincholé, Violeta Monasterio, Iwona Cygankiewicz, Antonio Bayés de Luna, Juan Pablo Martínez, Esther Pueyo, Pablo Laguna
BACKGROUND: Patients with chronic heart failure are at high risk of sudden cardiac death (SCD). Increased dispersion of repolarization restitution has been associated with SCD, and we hypothesize that this should be reflected in the morphology of the T-wave and its variations with heart rate. The aim of this study is to propose an electrocardiogram (ECG)-based index characterizing T-wave morphology restitution (TMR), and to assess its association with SCD risk in a population of chronic heart failure patients...
May 19, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28474934/mechanism-for-amplitude-alternans-in-electrocardiograms-and-the-initiation-of-spatiotemporal-chaos
#10
Diandian Diana Chen, Richard A Gray, Ilija Uzelac, Conner Herndon, Flavio H Fenton
It is widely believed that one major life-threatening transition to chaotic fibrillation occurs via spiral-wave breakup that is preceded by spatiotemporal dispersion of refractoriness due to alternations in the duration of the cardiac action potential (AP). However, recent clinical and experimental evidence suggests that other characteristics of the AP may contribute to, and perhaps drive, this dangerous dynamical instability. To identify the relative roles of AP characteristics, we performed experiments in rabbit hearts under conditions to minimize AP duration dynamics which unmasked pronounced AP amplitude alternans just before the onset of fibrillation...
April 21, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28448275/multi-band-decomposition-analysis-application-to-cardiac-alternans-as-a-function-of-temperature
#11
A Gizzi, A Loppini, E M Cherry, C Cherubini, F H Fenton, S Filippi
OBJECTIVE: It has long been known that variations in temperature can facilitate the development of cardiac arrhythmias. Here, we aim to quantify the effects of temperature on cardiac alternans properties. APPROACH: in this work, we use optical mapping recordings of canine ventricular epicardial preparations to demonstrate that hypothermia can promote the formation of alternans, which is an important precursor to potentially lethal arrhythmias like fibrillation. We then present a novel quantification of alternans properties for a broad range of cycle lengths under different thermal states...
May 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28416514/optical-mapping-approaches-on-muscleblind-like-compound-knockout-mice-for-understanding-mechanistic-insights-into-ventricular-arrhythmias-in-myotonic-dystrophy
#12
Chung-Chuan Chou, Po-Cheng Chang, Yi-Chia Wei, Kuang-Yung Lee
BACKGROUND: Cardiac arrhythmias are common causes of death in patients with myotonic dystrophy (dystrophia myotonica [DM]). Evidence shows that atrial tachyarrhythmia is an independent risk factor for sudden death; however, the relationship is unclear. METHODS AND RESULTS: Control wild-type (Mbnl1(+/+); Mbnl2(+/+) ) and DM mutant (Mbnl1(-/-); Mbnl2(+/-) ) mice were generated by crossing double heterozygous knockout (Mbnl1(+/-); Mbnl2(+/-) ) mice. In vivo electrophysiological study and optical mapping technique were performed to investigate mechanisms of ventricular tachyarrhythmias...
April 17, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28339589/the-clinical-value-of-t-wave-alternans-derived-from-holter-monitoring
#13
Joanna Lewek, Pawel Ptaszynski, Thomas Klingenheben, Iwona Cygankiewicz
Microvolt-level T-wave alternans (TWA) assessed by spectral method during an exercise stress test has been widely studied for risk stratification. Several studies have documented the association of a positive TWA with total mortality and arrhythmic events. Nevertheless, the need to achieve an elevated and stabilized heart rate resulting in a considerable proportion of indeterminate test results constitutes one of the main limitations of this method. It is well recognized that arrhythmic events may be triggered not only by physical but also by mental stress and are not necessarily associated with exercise...
October 6, 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28324970/development-of-data-acquisition-components-for-simultaneous-recording-of-3d-epicardial-and-surface-ecg-signals-in-the-langendorff-perfusion-apparatus
#14
Ryan Wade Selby, Anup Jonchhe, Chen Kaplan, Coeli M Lopes, Behnaz Ghoraani
Sudden Cardiac Death (SCD) claims 7 million lives per year. The importance of myocardial electrogram (EGM) repolarization alternans and surface electrocardiogram (ECG) T-wave alternans is gaining traction for understanding the underlying SCD mechanisms. However, the relationship between the 3D spatial distribution of myocardial EGMs and surface ECG with respect to SCD has yet to be investigated. To make this happen, a modified data acquisition system has been developed and fabricated in conjunction with the Langendorff perfusion system to enable simultaneous recording and analysis of the 3D spatial distribution of myocardial EGMs and the surface ECG...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28314848/effects-of-late-sodium-current-blockade-on-ventricular-refibrillation-in-a-rabbit-model
#15
COMPARATIVE STUDY
Mohammed Ali Azam, Nima Zamiri, Stéphane Massé, Marjan Kusha, Patrick F H Lai, Govind K Nair, Nigel S Tan, Christopher Labos, Kumaraswamy Nanthakumar
BACKGROUND: After defibrillation of initial ventricular fibrillation (VF), it is crucial to prevent refibrillation to ensure successful resuscitation outcomes. Inability of the late Na(+) current to inactivate leads to intracellular Ca(2+) dysregulation and arrhythmias. Our aim was to determine the effects of ranolazine and GS-967, inhibitors of the late Na(+) current, on ventricular refibrillation. METHODS AND RESULTS: Long-duration VF was induced electrically in Langendorff-perfused rabbit hearts (n=22) and terminated with a defibrillator after 6 minutes...
March 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28284506/temporary-removal-sudden-cardiac-death-the-role-of-imaging
#16
Pieter van der Bijl, Victoria Delgado, Jeroen J Bax
The publisher regrets that this article has been temporarily removed. A replacement will appear as soon as possible in which the reason for the removal of the article will be specified, or the article will be reinstated. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
March 6, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28268303/effects-and-underlying-mechanisms-of-refractory-period-pacing-on-repolarization-dynamics-in-the-human-heart
#17
Diogo Santos, Michele Orini, Xin Zhou, Alfonso Bueno-Orovio, Ben Hanson, Peter Taggart, Martin Hayward, Blanca Rodriguez, Pier Lambiase
Repolarization alternans is related to the initiation of life threatening cardiac arrhythmias. Experimental and computational studies suggest that the abolishment of alternans using dynamic pacing protocols may prevent abnormal heart rhythms. In a recent animal study, refractory period pacing (RPP) on every other beat has shown promising results in alternans reduction. However, the cellular mechanisms underlying this therapy and its efficiency in human patients remain unclear. In this study, in vivo unipolar electrograms acquired during RPP from 240 epicardial sites from one patient were analysed...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268301/pro-arrhythmic-effect-of-heart-rate-variability-during-periodic-pacing
#18
Kanchan Kulkarni, Steven W Lee, Elena G Tolkacheva
Clinically, healthy hearts have been associated with a high ventricular heart rate variability (HRV) while diseased hearts have been known to exhibit low ventricular HRV. Hence, low HRV is suggested to be a marker of cardiac ventricular arrhythmias. Over the past few years, there has been considerable amount of interest in incorporating HRV in pacing to emulate healthy heart conditions and re-stabilize the electrical activity in diseased hearts. Recently, we used single cell numerical simulations to demonstrate that HRV incorporated into periodic pacing promotes alternans formation and thus, can be pro-arrhythmic...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28257761/membrane-potential-determines-calcium-alternans-through-modulation-of-sr-ca-2-load-and-l-type-ca-2-current
#19
Giedrius Kanaporis, Lothar A Blatter
Alternans is a risk factor for cardiac arrhythmia, including atrial fibrillation. At the cellular level alternans is observed as beat-to-beat alternations in contraction, action potential (AP) morphology and magnitude of the Ca(2+) transient (CaT). It is widely accepted that the bi-directional interplay between membrane voltage and Ca(2+) is crucial for the development of alternans, however recently the attention has shifted to instabilities in cellular Ca(2+) handling, while the role of AP alternation remains poorly understood...
April 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28227084/development-of-data-acquisition-components-for-simultaneous-recording-of-3d-epicardial-and-surface-ecg-signals-in-the-langendorff-perfusion-apparatus
#20
Ryan Wade Selby, Anup Jonchhe, Chen Kaplan, Coeli M Lopes, Behnaz Ghoraani, Ryan Wade Selby, Anup Jonchhe, Chen Kaplan, Coeli M Lopes, Behnaz Ghoraani, Chen Kaplan, Behnaz Ghoraani, Anup Jonchhe, Coeli M Lopes, Ryan Wade Selby
Sudden Cardiac Death (SCD) claims 7 million lives per year. The importance of myocardial electrogram (EGM) repolarization alternans and surface electrocardiogram (ECG) T-wave alternans is gaining traction for understanding the underlying SCD mechanisms. However, the relationship between the 3D spatial distribution of myocardial EGMs and surface ECG with respect to SCD has yet to be investigated. To make this happen, a modified data acquisition system has been developed and fabricated in conjunction with the Langendorff perfusion system to enable simultaneous recording and analysis of the 3D spatial distribution of myocardial EGMs and the surface ECG...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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