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Ventricular depolarization

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https://www.readbyqxmd.com/read/28396856/bidomain-predictions-of-virtual-electrode-induced-make-and-break-excitations-around-blood-vessels
#1
Adam J Connolly, Edward Vigmond, Martin J Bishop
INTRODUCTION AND BACKGROUND: Virtual electrodes formed by field stimulation during defibrillation of cardiac tissue play an important role in eliciting activations. It has been suggested that the coronary vasculature is an important source of virtual electrodes, especially during low-energy defibrillation. This work aims to further the understanding of how virtual electrodes from the coronary vasculature influence defibrillation outcomes. METHODS: Using the bidomain model, we investigated how field stimulation elicited activations from virtual electrodes around idealized intramural blood vessels...
2017: Frontiers in Bioengineering and Biotechnology
https://www.readbyqxmd.com/read/28395022/optogenetic-manipulation-of-anatomical-re-entry-by-light-guided-generation-of-a-reversible-local-conduction-block
#2
Masaya Watanabe, Iolanda Feola, Rupamanjari Majumder, Wanchana Jangsangthong, Alexander S Teplenin, Dirk L Ypey, Martin J Schalij, Katja Zeppenfeld, Antoine A F de Vries, Daniël A Pijnappels
Aims: Anatomical re-entry is an important mechanism of ventricular tachycardia, characterized by circular electrical propagation in a fixed pathway. It's current investigative and therapeutic approaches are non-biological, rather unspecific (drugs), traumatizing (electrical shocks), or irreversible (ablation). Optogenetics is a new biological technique that allows reversible modulation of electrical function with unmatched spatiotemporal precision using light-gated ion channels. We therefore investigated optogenetic manipulation of anatomical re-entry in ventricular cardiac tissue...
March 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28382321/electrophysiological-mechanisms-of-long-and-short-qt-syndromes
#3
REVIEW
Gary Tse, Yin Wah Fiona Chan, Wendy Keung, Bryan P Yan
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored...
March 2017: IJC Heart & Vasculature
https://www.readbyqxmd.com/read/28381122/argon-exposure-induces-postconditioning-in-myocardial-ischemia-reperfusion
#4
Sandrine Lemoine, Katrien Blanchart, Mathieu Souplis, Adrien Lemaitre, Damien Legallois, Laurent Coulbault, Christophe Simard, Stéphane Allouche, Jacques H Abraini, Jean-Luc Hanouz, René Rouet, Laurent Sallé, Romain Guinamard, Alain Manrique
BACKGROUND AND PURPOSE: Cardioprotection against ischemia-reperfusion (I/R) damages remains a major concern during prehospital management of acute myocardial infarction. Noble gases have shown beneficial effects in preconditioning studies. Because emergency proceedings in the context of myocardial infarction require postconditioning strategies, we evaluated the effects of argon in such protocols on mammalian cardiac tissue. EXPERIMENTAL APPROACHES: In rat, cardiac I/R was induced in vivo by transient coronary artery ligature and cardiac functions were evaluated by magnetic resonance imaging...
January 1, 2017: Journal of Cardiovascular Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/28367337/premature-ventricular-complex-causing-ice-pick-headache
#5
Selcuk Ozturk, Ertan Yetkin
Ice pick headache is a momentary, transient, repetitive headache disorder and manifests with the stabbing pains and jolts. The exact mechanism causing this disease is unknown. Premature ventricular contractions are early depolarization of the ventricular myocardium and in the absence of a structural heart disease, it is considered to be a benign disease. In this report, we describe a male patient presenting with the symptom of momentary headache attacks accompanied with instant chest pain which is associated with premature ventricular contraction...
2017: Case Reports in Cardiology
https://www.readbyqxmd.com/read/28336184/atrial-fibrillation-management-in-a-breeding-stallion
#6
N Heliczer, K Mitchell, O Lorello, J Dauvillier, D Burger, C C Schwarzwald, C Navas de Solis
A 20-year-old warmblood breeding stallion presented to a University practice for semen collection and evaluation was incidentally diagnosed with atrial fibrillation (AF). Electrocardiogram recordings during breeding revealed inappropriately rapid tachycardia and occasional ventricular premature depolarizations/aberrant ventricular conduction. Transvenous electrical cardioversion was performed. After successful cardioversion the horse displayed supraventricular ectopy and atrial contractile dysfunction and was administered sotalol hydrochloride in an attempt to decrease the risk of AF recurrence...
March 20, 2017: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
https://www.readbyqxmd.com/read/28329148/myocardial-energy-metabolism-and-ultrastructure-with-polarizing-and-depolarizing-cardioplegia-in-a-porcine-model%C3%A2
#7
Terje Aass, Lodve Stangeland, David J Chambers, Seth Hallström, Christine Rossmann, Bruno K Podesser, Malte Urban, Knut Nesheim, Rune Haaverstad, Knut Matre, Ketil Grong
OBJECTIVES: This study investigated whether the novel St. Thomas' Hospital polarizing cardioplegic solution (STH-POL) with esmolol/adenosine/magnesium offers improved myocardial protection by reducing demands for high-energy phosphates during cardiac arrest compared to the depolarizing St. Thomas' Hospital cardioplegic solution No 2 (STH-2). METHODS: Twenty anaesthetised pigs on tepid cardiopulmonary bypass were randomized to cardiac arrest for 60 min with antegrade freshly mixed, repeated, cold, oxygenated STH-POL or STH-2 blood cardioplegia every 20 min...
March 2, 2017: European Journal of Cardio-thoracic Surgery
https://www.readbyqxmd.com/read/28294644/electrocardiogram-changes-and-atrial-arrhythmias-in-individuals-carrying-sodium-channel-scn5a-d1275n-mutation
#8
Sari U M Vanninen, Kjell Nikus, Katriina Aalto-Setälä
INTRODUCTION: The cardiac sodium channel SCN5A regulates atrioventricular and ventricular depolarization as well as cardiac conduction. Patients with cardiac electrical abnormalities have an increased risk of sudden cardiac death (SCD) and cardio-embolic stroke. Optimal management of cardiac disease includes the understanding of association between the causative mutations and the clinical phenotype. A 12-lead electrocardiogram (ECG) is an easy and inexpensive tool for finding risk patients...
March 15, 2017: Annals of Medicine
https://www.readbyqxmd.com/read/28265681/ischemia-induced-drp1-and-fis1-mediated-mitochondrial-fission-and-right-ventricular-dysfunction-in-pulmonary-hypertension
#9
Lian Tian, Monica Neuber-Hess, Jeffrey Mewburn, Asish Dasgupta, Kimberly Dunham-Snary, Danchen Wu, Kuang-Hueih Chen, Zhigang Hong, Willard W Sharp, Shelby Kutty, Stephen L Archer
Right ventricular (RV) function determines prognosis in pulmonary arterial hypertension (PAH). We hypothesize that ischemia causes RV dysfunction in PAH by triggering dynamin-related protein 1 (Drp1)-mediated mitochondrial fission. RV function was compared in control rats (n = 50) versus rats with monocrotaline-induced PAH (MCT-PAH; n = 60) both in vivo (echocardiography) and ex vivo (RV Langendorff). Mitochondrial membrane potential and morphology and RV function were assessed before or after 2 cycles of ischemia-reperfusion injury challenge (RV-IR)...
April 2017: Journal of Molecular Medicine: Official Organ of the "Gesellschaft Deutscher Naturforscher und Ärzte"
https://www.readbyqxmd.com/read/28262340/gain-of-function-mutation-in-scn5a-causes-ventricular-arrhythmias-and-early-onset-atrial-fibrillation
#10
Krystien V Lieve, Arie O Verkerk, Svitlana Podliesna, Christian van der Werf, Michael W Tanck, Nynke Hofman, Paul F van Bergen, Leander Beekman, Connie R Bezzina, Arthur A M Wilde, Elisabeth M Lodder
BACKGROUND: Mutations in SCN5A, the gene encoding the α-subunit of the cardiac sodium channel (NaV1.5), are associated with a broad spectrum of inherited cardiac arrhythmia disorders. The purpose of this study was to identify the genetic and functional determinants underlying a Dutch family that presented with a combined phenotype of ventricular arrhythmias with a likely adrenergic component, either in isolation or in combination with a mildly decreased heart function and early onset (<55years) atrial fibrillation...
January 29, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28262257/t-wave-axis-deviation-and-qrs-t-angle-controversial-indicators-of-incident-coronary-heart-events
#11
REVIEW
Polychronis Dilaveris, Christos-Konstantinos Antoniou, Konstantinos Gatzoulis, Dimitrios Tousoulis
Abnormal orientation of the T-wave axis and increased angle between the QRS complex (depolarization) and the T-wave (repolarization) have long been assumed to provide a global measure of repolarization abnormality, and have been used to assess ventricular repolarization. The ability of the T wave axis deviation and the QRS-T angle to predict incident coronary heart events was examined in several studies. However, conflicting results have led to significant controversy in the literature concerning their purported ability...
February 20, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28258544/effect-of-loss-of-heart-rate-variability-on-t-wave-heterogeneity-and-qt-variability-in-heart-failure-patients-implications-in-ventricular-arrhythmogenesis
#12
Sachin Nayyar, Muhammad A Hasan, Kurt C Roberts-Thomson, Thomas Sullivan, Mathias Baumert
Heart rate variability (HRV) modulates dynamics of ventricular repolarization. A diminishing value of HRV is associated with increased vulnerability to life-threatening ventricular arrhythmias, however the causal relationship is not well-defined. We evaluated if fixed-rate atrial pacing that abolishes the effect of physiological HRV, will alter ventricular repolarization wavefronts and is relevant to ventricular arrhythmogenesis. The study was performed in 16 subjects: 8 heart failure patients with spontaneous ventricular tachycardia [HFVT], and 8 subjects with structurally normal hearts (H Norm)...
March 3, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28253365/virtual-electrodes-around-anatomical-structures-and-their-roles-in-defibrillation
#13
Adam Connolly, Edward Vigmond, Martin Bishop
BACKGROUND: Virtual electrodes from structural/conductivity heterogeneities are known to elicit wavefront propagation, upon field-stimulation, and are thought to be important for defibrillation. In this work we investigate how the constitutive and geometrical parameters associated with such anatomical heterogeneities, represented by endo/epicardial surfaces and intramural surfaces in the form of blood-vessels, affect the virtual electrode patterns produced. METHODS AND RESULTS: The steady-state bidomain model is used to obtain, using analytical and numerical methods, the virtual electrode patterns created around idealized endocardial trabeculations and blood-vessels...
2017: PloS One
https://www.readbyqxmd.com/read/28236155/cardiac-magnetic-resonance-imaging-and-electroanatomic-voltage-discordance-in-non-ischemic-left-ventricle-ventricular-tachycardia-and-premature-ventricular-depolarizations
#14
Brian P Betensky, Wei Dong, Benjamin A D'Souza, Erica S Zado, Yuchi Han, Francis E Marchlinski
PURPOSE: Magnetic resonance imaging (MRI) with late gadolinium enhancement is commonly performed in patients with non-ischemic LV ventricular tachycardia/ventricular premature depolarizations (non-ischemic LV-VT/VPDs) to define VT substrate prior to catheter ablation. We investigated the prevalence of abnormal voltage and VT localized to areas of the myocardium not reported to have late gadolinium enhancement (LGE) on routine pre-procedural MRI and sought to determine if quantitative MRI analysis could reduce this discordance...
February 24, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28202194/study-of-factors-affecting-the-progression-and-termination-of-drug-induced-torsade-de-pointes-in-two-dimensional-cardiac-tissue
#15
Ponnuraj Kirthi Priya, M Ramasubba Reddy
INTRODUCTION: To study the conditions leading to the initiation and termination of drug induced Torsade de pointes (TdP) along with QT prolongation. METHODS: A 2D anisotropic transmural section of the ventricular myocardium is modeled using the TP06 equations and the cells are interconnected with gap junction conductances (GJC). The tissue is remodeled by reducing the repolarization reserve (by increasing calcium current (ICaL)) of all cells thus making them vulnerable to development of early after depolarizations (EADs)...
February 2, 2017: Journal of Electrocardiology
https://www.readbyqxmd.com/read/28184198/local-left-ventricular-epicardial-j-waves-and-late-potentials-in-brugada-syndrome-patients-with-inferolateral-early-repolarization-pattern
#16
Satoshi Nagase, Masamichi Tanaka, Hiroshi Morita, Koji Nakagawa, Tadashi Wada, Masato Murakami, Nobuhiro Nishii, Kazufumi Nakamura, Hiroshi Ito, Tohru Ohe, Kengo F Kusano
Background: Brugada syndrome (BrS) is characterized by J-point or ST-segment elevation on electrocardiograms (ECGs) and increased risk of ventricular fibrillation (VF). In BrS, epicardial depolarization abnormality with delayed potential on the right ventricular outflow tract is reportedly the predominant mechanism underlying VF. Yet VF occurrence is also associated with early repolarization (ER) pattern in the inferolateral ECG leads, which may represent the inferior and/or left lateral ventricular myocardium...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28182562/in-silico-modeling-of-the-functional-role-of-reduced-sialylation-in-sodium-and-potassium-channel-gating-of-mouse-ventricular-myocytes
#17
Dongping Du, Hui Yang, Andrew R Ednie, Eric S Bennett
Cardiac ion channels are highly glycosylated membrane proteins, with up to 30% of the protein's mass containing glycans. Heart diseases often accompany individuals with congenital disorders of glycosylation (CDG). However, cardiac dysfunction among CDG patients is not yet fully understood. There is an urgent need to study how aberrant glycosylation impacts cardiac electrical signaling. Our previous works reported that congenitally reduced sialylation achieved through deletion of the sialyltransferase gene, ST3Gal4, leads to altered gating of voltage-gated Na+ and K+ channels (Nav and Kv, respectively)...
February 6, 2017: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28170198/differential-mechanisms-of-myocardial-conduction-slowing-by-adipose-tissue-derived-stromal-cells-derived-from-different-species
#18
Judith N Ten Sande, Nicoline W Smit, Mojtaba Parvizi, Shirley C M van Amersfoorth, Josée A Plantinga, Pascal F H M van Dessel, Jacques M T de Bakker, Marco C Harmsen, Ruben Coronel
Stem cell therapy is a promising therapeutic option to treat patients after myocardial infarction. However, the intramyocardial administration of large amounts of stem cells might generate a proarrhythmic substrate. Proarrhythmic effects can be explained by electrotonic and/or paracrine mechanisms. The narrow therapeutic time window for cell therapy and the presence of comorbidities limit the application of autologous cell therapy. The use of allogeneic or xenogeneic stem cells is a potential alternative to autologous cells, but differences in the proarrhythmic effects of adipose-derived stromal cells (ADSCs) across species are unknown...
January 2017: Stem Cells Translational Medicine
https://www.readbyqxmd.com/read/28140304/electrical-approach-to-improve-left-ventricular-activation-during-right-ventricle-stimulation
#19
María Paula Bonomini, Daniel F Ortega, Luis D Barja, Nicolasa Mangani, Analía Paolucci, Emilio Logarzo
Coronary sinus mapping is commonly used to evaluate left atrial activation. Herein, we propose to use it to assess which right ventricular pacing modality produces the shortest left ventricular activation times (R-LVtime) and the narrowest QRS widths. Three study groups were defined: 54 controls without intraventricular conduction disturbances; 15 patients with left bundle branch block, and other 15 with right bundle branch block. Left ventricular activation times and QRS widths were evaluated among groups under sinus rhythm, right ventricular apex, right ventricular outflow tract and high output septal zone (SEPHO)...
2017: Medicina
https://www.readbyqxmd.com/read/28097316/evaluation-of-structural-progression-in-arrhythmogenic-right-ventricular-dysplasia-cardiomyopathy
#20
Thomas P Mast, Cynthia A James, Hugh Calkins, Arco J Teske, Crystal Tichnell, Brittney Murray, Peter Loh, Stuart D Russell, Birgitta K Velthuis, Daniel P Judge, Dennis Dooijes, Ryan J Tedford, Jeroen F van der Heijden, Harikrishna Tandri, Richard N Hauer, Theodore P Abraham, Pieter A Doevendans, Anneline S J M Te Riele, Maarten J Cramer
Importance: Considerable research has described the arrhythmic course of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). However, objective data characterizing structural progression, such as ventricular enlargement and cardiac dysfunction, in ARVD/C are relatively scarce. Objectives: To define the extent of structural progression, identify determinants of structural progression, and determine the association between structural progression and electrocardiographic (ECG) changes in patients with ARVD/C...
March 1, 2017: JAMA Cardiology
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