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Cardiac alternans

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https://www.readbyqxmd.com/read/28916174/evaluation-of-beat-to-beat-ventricular-repolarization-lability-from-standard-12-lead-ecg-during-acute-myocardial-ischemia
#1
Salah S Al-Zaiti, Mohammad Alrawashdeh, Christian Martin-Gill, Clifton Callaway, David Mortara, Jan Nemec
BACKGROUND: Acute myocardial ischemia is a common cause of ventricular arrhythmias, yet recent ECG methods predicting susceptibility to ventricular tachyarrhythmia have not been fully evaluated during spontaneous ischemia. We sought to evaluate the clinical utility of alternans and non-alternans components of repolarization variability from the standard 10-second 12-lead ECG signals to risk stratify patients with acute chest pain. METHODS: We enrolled consecutive, non-traumatic, chest pain patients transported through Emergency Medical Services (EMS) to three tertiary care hospitals with cardiac catheterization lab capabilities in Pittsburgh, PA...
August 10, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28903013/spatiotemporally-non-uniform-ca-2-dynamics-of-cardiac-purkinje-fibers-in-mouse-myocardial-infarct
#2
Taka-Aki Matsuyama, Hideo Tanaka, Hatsue Ishibashi-Ueda, Tetsuro Takamatsu
Surviving Purkinje fibers in myocardial infarct are regarded as an important substrate in arrhythmogenesis. However, poorly understood are functional properties of Purkinje fibers in the infarcted heart. We sought to visualize intracellular Ca(2+) ([Ca(2+)]i) dynamics of Purkinje fiber networks in the mouse myocardial infarct. Using 3- to 4-day-old or 7- to 9-day-old infarcted hearts after the left coronary-artery ligation corresponding, respectively, to acute or healing phase, we conducted rapid fluo4-fluorescence imaging on the endocardial surface of the left ventricular septum by macro-zoom fluorescence microscopy and rapid-scanning confocal microscopy...
September 1, 2017: Journal of Histochemistry and Cytochemistry: Official Journal of the Histochemistry Society
https://www.readbyqxmd.com/read/28859079/a-computational-model-of-spatio-temporal-cardiac-intracellular-calcium-handling-with-realistic-structure-and-spatial-flux-distribution-from-sarcoplasmic-reticulum-and-t-tubule-reconstructions
#3
Michael A Colman, Christian Pinali, Andrew W Trafford, Henggui Zhang, Ashraf Kitmitto
Intracellular calcium cycling is a vital component of cardiac excitation-contraction coupling. The key structures responsible for controlling calcium dynamics are the cell membrane (comprising the surface sarcolemma and transverse-tubules), the intracellular calcium store (the sarcoplasmic reticulum), and the co-localisation of these two structures to form dyads within which calcium-induced-calcium-release occurs. The organisation of these structures tightly controls intracellular calcium dynamics. In this study, we present a computational model of intracellular calcium cycling in three-dimensions (3-D), which incorporates high resolution reconstructions of these key regulatory structures, attained through imaging of tissue taken from the sheep left ventricle using serial block face scanning electron microscopy...
August 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28842915/roles-of-impaired-intracellular-calcium-cycling-in-arrhythmogenicity-of-diabetic-mouse-model
#4
Chung-Chuan Chou, Chien-Te Ho, Hui-Ling Lee, Yen Chu, Tzung-Hai Yen, Ming-Shien Wen, Shien-Fong Lin, Cheng-Hung Lee, Po-Cheng Chang
BACKGROUND: Diabetes mellitus is associated an increased risk of ventricular arrhythmias (VA), but the underlying electrophysiological mechanisms are not fully explored. This study was aimed to test whether dynamic factors and Cai handling play roles in arrhythmogenesis of a diabetic animal model. METHODS: We used 26 db/db type 2 diabetes mice and 28 control mice in this study. VA inducibility was evaluated in vivo under isoflurane general anesthesia. The intracellular Ca(2+) (Cai ) and membrane voltage (Vm ) signals of the Langendorff-perfused mouse hearts were simultaneously recorded using the optical mapping technique...
August 26, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28821956/effects-of-ageing-on-pro-arrhythmic-ventricular-phenotypes-in-incrementally-paced-murine-pgc-1%C3%AE-hearts
#5
Shiraz Ahmad, Haseeb Valli, Charlotte E Edling, Andrew A Grace, Kamalan Jeevaratnam, Christopher L-H Huang
A range of chronic clinical conditions accompany cardiomyocyte energetic dysfunction and constitute independent risk factors for cardiac arrhythmia. We investigated pro-arrhythmic and arrhythmic phenotypes in energetically deficient C57BL mice with genetic ablation of the mitochondrial promoter peroxisome proliferator-activated receptor-γ coactivator-1β (Pgc-1β), a known model of ventricular arrhythmia. Pro-arrhythmic and cellular action potential (AP) characteristics were compared in intact Langendorff-perfused hearts from young (12-16 week) and aged (> 52 week), wild-type (WT) and Pgc-1β (-/-) mice...
August 18, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28745301/automatic-detection-of-t-wave-alternans-using-tensor-decompositions-in-multilead-ecg-signals
#6
Griet Goovaerts, Bert Vandenberk, Rik Willems, Sabine Van Huffel
OBJECTIVE: T wave alternans (TWA) is a promising non-invasive risk stratification tool for sudden cardiac death which can be detected from surface ECG. This paper proposes a novel method to automatically detect TWA based on tensor decomposition methods. APPROACH: Two different tensor decomposition approaches are examined and compared, namely canonical polyadic decomposition and the more generalized variation PARAFAC2 which allows the T waves to shift in time. RESULTS AND SIGNIFICANCE: Results on different artificial and clinical signals show that the presented methods are a robust and reliable way for TWA detection, and show the potential benefit of tensors in ECG signal processing...
July 26, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28708197/risk-stratification-personalised-model-for-prediction-of-life-threatening-ventricular-tachyarrhythmias-in-patients-with-chronic-heart-failure
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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-postinfarction-border-zone-cardiomyocytes-a-computational-analysis
#14
Jakub Tomek, Blanca Rodriguez, Gil Bub, Jordi Heijman
The border zone (BZ) of the viable myocardium adjacent to an infarct undergoes extensive autonomic and electrical remodeling and is prone to repolarization alternans-induced cardiac arrhythmias. BZ remodeling processes may promote or inhibit Ca(2+) and/or repolarization alternans and may differentially affect ventricular arrhythmogenesis. Here, we used 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 (β-AR) stimulation...
August 1, 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
#15
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
#16
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
#17
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
#18
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
#19
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...
April 1, 2017: 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
#20
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
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