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https://www.readbyqxmd.com/read/27517161/nonlinear-physics-of-electrical-wave-propagation-in-the-heart-a-review
#1
Sergio Alonso, Markus Bär, Blas Echebarria
The beating of the heart is a synchronized contraction of muscle cells (myocytes) that is triggered by a periodic sequence of electrical waves (action potentials) originating in the sino-atrial node and propagating over the atria and the ventricles. Cardiac arrhythmias like atrial and ventricular fibrillation (AF,VF) or ventricular tachycardia (VT) are caused by disruptions and instabilities of these electrical excitations, that lead to the emergence of rotating waves (VT) and turbulent wave patterns (AF,VF)...
September 2016: Reports on Progress in Physics
https://www.readbyqxmd.com/read/27422985/partial-ik1-blockade-destabilizes-spiral-wave-rotation-center-without-inducing-wave-breakup-and-facilitates-termination-of-reentrant-arrhythmias-in-ventricles
#2
Yasunori Kushiyama, Haruo Honjo, Ryoko Niwa, Hiroki Takanari, Masatoshi Yamazaki, Yoshio Takemoto, Ichiro Sakuma, Itsuo Kodama, Kaichiro Kamiya
It has been reported that blockade of the inward rectifier K(+) current (IK1) facilitates termination of ventricular fibrillation. We hypothesized that partial IK1 blockade destabilizes spiral wave (SW) re-entry, leading to its termination. Optical action potential (AP) signals were recorded from left ventricles of Langendorff-perfused rabbit hearts with endocardial cryoablation. The dynamics of SW re-entry were analyzed during ventricular tachycardia (VT), induced by cross-field stimulation. Intercellular electrical coupling in the myocardial tissue was evaluated by the space constant...
September 1, 2016: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/26608802/sequential-radial-and-circumferential-strain-and-oxidative-stress-assessment-in-dogs-with-tachycardia-induced-cardiac-dysfunction
#3
Telma Mary Nakata, Naoya Matsuura, Hideki Kaji, Miki Shimizu, Ryuji Fukushima, Noboru Machida, Ryou Tanaka
UNLABELLED: Quantitative analysis of left ventricular (LV) deformation based on two-dimensional speckle tracking echocardiography (2D STE) has increasingly been used to assess segmental and global function because conventional echocardiography is influenced by tethering effects of adjacent myocardium and cardiac translational motion. HYPOTHESIS: (1) 2D STE can be useful to detect subtle regional changes in the LV contractility during development of tachycardia-induced cardiomyopathy (TIC) to heart failure in awake dog; (2) oxidized glutathione (GSSG) and reduced glutathione (GSH) levels are associated with the development of its respective segmental wall motion abnormalities (WMA)...
April 2016: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/26311213/clarifying-the-anatomy-of-hearts-with-concordant-ventriculo-arterial-connections-but-abnormally-related-arterial-trunks
#4
Saurabh K Gupta, Sivasubramanian Ramakrishnan, Gurpreet S Gulati, G William Henry, Diane E Spicer, Carl L Backer, Robert H Anderson
Hearts in which the arterial trunks arise from the morphologically appropriate ventricles, but in a parallel manner, rather than the usual spiralling arrangement, have long fascinated anatomists. These rare entities, for quite some time, were considered embryological impossibilities, but ongoing experience has shown that they can be found in various segmental combinations. Problems still exist about how best to describe them, as the different variants are often described with esoteric terms, such as anatomically corrected malposition or isolated ventricular inversion...
January 2016: Cardiology in the Young
https://www.readbyqxmd.com/read/26001644/the-effects-of-remodeling-with-heart-failure-on-mode-of-initiation-of-ventricular-fibrillation-and-its-spatiotemporal-organization
#5
Thomas H Everett, George S Hulley, Ken W Lee, Roger Chang, Emily E Wilson, Jeffrey E Olgin
PURPOSE: The effect of the heart failure substrate on the initiation of ventricular fibrillation (VF) and its resulting mechanism is not known. The objective of this study was to determine the effects of substrate on VF initiation and its spatiotemporal organization in the heart failure model. METHODS: Optical action potentials were recorded from LV wedge preparations either from structurally normal hearts (control, n = 11) or from congestive heart failure (CHF; n = 7), at the epicardial surface, endocardial surface which included a papillary muscle, and a transmural cross section...
September 2015: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/25838872/morphological-study-of-chordae-tendinae-in-human-cadaveric-hearts
#6
S A Gunnal, R N Wabale, M S Farooqui
OBJECTIVES: The chordae tendinae (CT) are strong, fibrous connections between the valve leaflets and the papillary muscles. Dysfunction of the papillary muscles and chordae is frequent. Mitral valve replacement with preservation of CT and papillary muscles may preserve postoperative left ventricular function better than conventional mitral valve replacement in patients with chronic mitral regurgitation. METHODS: The study was carried out on 116 human cadaveric hearts...
January 2015: Heart Views: the Official Journal of the Gulf Heart Association
https://www.readbyqxmd.com/read/24749165/spiral-hypertrophic-cardiomyopathy-as-detected-by-cardiac-magnetic-resonance
#7
Nessim Amin, Ronald B Williams, June A Yarmozik, Robert W W Biederman
Hypertrophic cardiomyopathy (HCM) is a genetically determined heart muscle disease; characterized by left ventricular hypertrophy (LVH). Spiral HCM is described as having a counterclockwise rotation pattern of hypertrophy along with variable degrees of fibrosis. A 34-year-old female presented with symptoms suggestive of heart failure. Echocardiography showed concentric LVH with normal contractility. Cardiac MRI showed asymmetric septal hypertrophy with mid-cavity obliteration and a spiral pattern of variably increasing wall thickness...
March 2014: Echocardiography
https://www.readbyqxmd.com/read/24449819/does-transendocardial-injection-of-mesenchymal-stem-cells-improve-myocardial-function-locally-or-globally-an-analysis-from-the-percutaneous-stem-cell-injection-delivery-effects-on-neomyogenesis-poseidon-randomized-trial
#8
RANDOMIZED CONTROLLED TRIAL
Viky Y Suncion, Eduard Ghersin, Joel E Fishman, Juan Pablo Zambrano, Vasileios Karantalis, Nicole Mandel, Katarina H Nelson, Gary Gerstenblith, Darcy L DiFede Velazquez, Elayne Breton, Kranthi Sitammagari, Ivonne H Schulman, Sabrina N Taldone, Adam R Williams, Cristina Sanina, Peter V Johnston, Jeffrey Brinker, Peter Altman, Muzammil Mushtaq, Barry Trachtenberg, Adam M Mendizabal, Melissa Tracy, Jose Da Silva, Ian K McNiece, Alberto C Lardo, Richard T George, Joshua M Hare, Alan W Heldman
RATIONALE: Transendocardial stem cell injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the effect of the injection site remains unknown. OBJECTIVE: To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in noninjected segments. METHODS AND RESULTS: Biplane ventriculographic and endocardial tracings were recorded...
April 11, 2014: Circulation Research
https://www.readbyqxmd.com/read/24023798/spiral-wave-dynamics-in-a-mathematical-model-of-human-ventricular-tissue-with-myocytes-and-fibroblasts
#9
Alok Ranjan Nayak, T K Shajahan, A V Panfilov, Rahul Pandit
Cardiac fibroblasts, when coupled functionally with myocytes, can modulate the electrophysiological properties of cardiac tissue. We present systematic numerical studies of such modulation of electrophysiological properties in mathematical models for (a) single myocyte-fibroblast (MF) units and (b) two-dimensional (2D) arrays of such units; our models build on earlier ones and allow for zero-, one-, and two-sided MF couplings. Our studies of MF units elucidate the dependence of the action-potential (AP) morphology on parameters such as [Formula: see text], the fibroblast resting-membrane potential, the fibroblast conductance [Formula: see text], and the MF gap-junctional coupling [Formula: see text]...
2013: PloS One
https://www.readbyqxmd.com/read/22707561/inhibition-of-intercellular-coupling-stabilizes-spiral-wave-reentry-whereas-enhancement-of-the-coupling-destabilizes-the-reentry-in-favor-of-early-termination
#10
Yoshio Takemoto, Hiroki Takanari, Haruo Honjo, Norihiro Ueda, Masahide Harada, Sara Kato, Masatoshi Yamazaki, Ichiro Sakuma, Tobias Opthof, Itsuo Kodama, Kaichiro Kamiya
Spiral-wave (SW) reentry is a major organizing principle of ventricular tachycardia/fibrillation (VT/VF). We tested a hypothesis that pharmacological modification of gap junction (GJ) conductance affects the stability of SW reentry in a two-dimensional (2D) epicardial ventricular muscle layer prepared by endocardial cryoablation of Langendorff-perfused rabbit hearts. Action potential signals were recorded and analyzed by high-resolution optical mapping. Carbenoxolone (CBX; 30 μM) and rotigaptide (RG, 0.1 μM) were used to inhibit and enhance GJ coupling, respectively...
September 1, 2012: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/22645368/heart-wall-myofibers-are-arranged-in-minimal-surfaces-to-optimize-organ-function
#11
Peter Savadjiev, Gustav J Strijkers, Adrianus J Bakermans, Emmanuel Piuze, Steven W Zucker, Kaleem Siddiqi
Heart wall myofibers wind as helices around the ventricles, strengthening them in a manner analogous to the reinforcement of concrete cylindrical columns by spiral steel cables [Richart FE, et al. (1929) Univ of Illinois, Eng Exp Stn Bull 190]. A multitude of such fibers, arranged smoothly and regularly, contract and relax as an integrated functional unit as the heart beats. To orchestrate this motion, fiber tangling must be avoided and pumping should be efficient. Current models of myofiber orientation across the heart wall suggest groupings into sheets or bands, but the precise geometry of bundles of myofibers is unknown...
June 12, 2012: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/22641132/pharmacological-blockade-of-iks-destabilizes-spiral-wave-reentry-under-%C3%AE-adrenergic-stimulation-in-favor-of-its-early-termination
#12
Sara Kato, Haruo Honjo, Yoshio Takemoto, Hiroki Takanari, Tomoyuki Suzuki, Yusuke Okuno, Tobias Opthof, Ichiro Sakuma, Shin Inada, Kazuo Nakazawa, Takashi Ashihara, Itsuo Kodama, Kaichiro Kamiya
We tested a hypothesis that an enhancement of I(Ks) may play a pivotal role in ventricular proarrhythmia under high sympathetic activity. A 2-dimensional ventricular muscle layer was prepared in rabbit hearts, and action potential signals were analyzed by optical mapping. During constant stimulation, isoproterenol (ISP, 0.1 µM) significantly shortened action potential duration (APD); chromanol 293B (30 µM), a selective I(Ks)-blocker, reversed the APD shortening. VTs induced in the presence of ISP lasted longer than in the control, and this was reversed by 293B...
2012: Journal of Pharmacological Sciences
https://www.readbyqxmd.com/read/21483682/scroll-wave-dynamics-in-human-cardiac-tissue-lessons-from-a-mathematical-model-with-inhomogeneities-and-fiber-architecture
#13
Rupamanjari Majumder, Alok Ranjan Nayak, Rahul Pandit
Cardiac arrhythmias, such as ventricular tachycardia (VT) and ventricular fibrillation (VF), are among the leading causes of death in the industrialized world. These are associated with the formation of spiral and scroll waves of electrical activation in cardiac tissue; single spiral and scroll waves are believed to be associated with VT whereas their turbulent analogs are associated with VF. Thus, the study of these waves is an important biophysical problem. We present a systematic study of the combined effects of muscle-fiber rotation and inhomogeneities on scroll-wave dynamics in the TNNP (ten Tusscher Noble Noble Panfilov) model for human cardiac tissue...
2011: PloS One
https://www.readbyqxmd.com/read/21157118/bepridil-facilitates-early-termination-of-spiral-wave-reentry-in-two-dimensional-cardiac-muscle-through-an-increase-of-intercellular-electrical-coupling
#14
Hiroki Takanari, Haruo Honjo, Yoshio Takemoto, Tomoyuki Suzuki, Sara Kato, Masahide Harada, Yusuke Okuno, Takashi Ashihara, Tobias Opthof, Ichiro Sakuma, Kaichiro Kamiya, Itsuo Kodama
Bepridil is effective for conversion of atrial fibrillation to sinus rhythm and in the treatment of drug-refractory ventricular tachyarrhythmias. We investigated the effects of bepridil on electrophysiological properties and spiral-wave (SW) reentry in a 2-dimensional ventricular muscle layer of isolated rabbit hearts by optical mapping. Ventricular tachycardia (VT) induced in the presence of bepridil (1 µM) terminated earlier than in the control. Bepridil increased action potential duration (APD) by 5% - 8% under constant pacing and significantly increased the space constant...
2011: Journal of Pharmacological Sciences
https://www.readbyqxmd.com/read/19815825/spiral-waves-and-reentry-dynamics-in-an-in-vitro-model-of-the-healed-infarct-border-zone
#15
Marvin G Chang, Yibing Zhang, Connie Y Chang, Linmiao Xu, Roland Emokpae, Leslie Tung, Eduardo Marbán, M Roselle Abraham
RATIONALE: Reentry underlies most ventricular tachycardias (VTs) seen postmyocardial infarction (MI). Mapping studies reveal that the majority of VTs late post-MI arise from the infarct border zone (IBZ). OBJECTIVE: To investigate reentry dynamics and the role of individual ion channels on reentry in in vitro models of the "healed" IBZ. METHODS AND RESULTS: We designed in vitro models of the healed IBZ by coculturing skeletal myotubes with neonatal rat ventricular myocytes and performed optical mapping at high temporal and spatial resolution...
November 20, 2009: Circulation Research
https://www.readbyqxmd.com/read/19303369/early-termination-of-spiral-wave-reentry-by-combined-blockade-of-na-and-l-type-ca2-currents-in-a-perfused-two-dimensional-epicardial-layer-of-rabbit-ventricular-myocardium
#16
COMPARATIVE STUDY
Yuko S Ishiguro, Haruo Honjo, Tobias Opthof, Yusuke Okuno, Harumichi Nakagawa, Masatoshi Yamazaki, Masahide Harada, Hiroki Takanari, Tomoyuki Suzuki, Mikio Morishima, Ichiro Sakuma, Kaichiro Kamiya, Itsuo Kodama
BACKGROUND: Modification of spiral wave (SW) reentry by antiarrhythmic drugs is a central issue to be challenged for better understanding of their benefits and risks. OBJECTIVE: We investigated the effects of pilsicainide and/or verapamil, which block sodium and L-type calcium currents (I(Na) and I(Ca,L)), respectively, on SW reentry. METHODS: A two-dimensional epicardial ventricular muscle layer was created in rabbit hearts by cryoablation (n = 32), and action potential signals were analyzed by high-resolution optical mapping...
May 2009: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/19064692/cardiac-mechanics-revisited-the-relationship-of-cardiac-architecture-to-ventricular-function
#17
REVIEW
Gerald Buckberg, Julien I E Hoffman, Aman Mahajan, Saleh Saleh, Cecil Coghlan
The keynote to understanding cardiac function is recognizing the underlying architecture responsible for the contractile mechanisms that produce the narrowing, shortening, lengthening, widening, and twisting disclosed by echocardiographic and magnetic resonance technology. Despite background knowledge of a spiral clockwise and counterclockwise arrangement of muscle fibers, issues about the exact architecture, interrelationships, and function of the different sets of muscle fibers remain to be resolved. This report (1) details observed patterns of cardiac dynamic directional and twisting motions via multiple imaging sources; (2) summarizes the deficiencies of correlations between ventricular function and known ventricular muscle architecture; (3) correlates known cardiac motions with the functional anatomy within the helical ventricular myocardial band; and (4) defines an innovative muscular systolic mechanism that challenges the previously described concept of "isovolumic relaxation...
December 9, 2008: Circulation
https://www.readbyqxmd.com/read/18598986/a-new-look-at-diastole
#18
REVIEW
Julien I E Hoffman, Aman Mahajan, Cecil Coghlan, Saleh Saleh, Gerald D Buckberg
The isovolumic period following systolic ejection is associated with untwisting of the apex that follows systolic torsion of the left ventricle, with simultaneous generation of negative pressures in the left ventricle. Previous studies have described this period as isovolumic relaxation, and have regarded the untwisting as entirely caused by restoring elastic forces. However, evidence from several sources indicates that some ventricular muscle is still contracting during this period, and that this muscle is subepicardial muscle or the ascending spiral segment of the ventricular myocardial band that extends from the apex up along the left ventricular epicardium and the right ventricular side of the septum to the root of the aorta...
July 2008: Heart Failure Clinics
https://www.readbyqxmd.com/read/18598977/embryogenesis-of-the-heart-muscle
#19
REVIEW
David Sedmera, Tim McQuinn
This article concerns the development of myocardial architecture--crucial for contractile performance of the heart and its conduction system, essential for generation and coordinated spread of electrical activity. Topics discussed include molecular determination of cardiac phenotype (contractile and conducting), remodeling of ventricular wall architecture and its blood supply, and relation of trabecular compaction to noncompaction cardiomyopathy. Illustrated are the structure and function of the tubular heart, time course of trabecular compaction, and development of multilayered spiral systems of the compact layer...
July 2008: Heart Failure Clinics
https://www.readbyqxmd.com/read/17635652/sustained-spiral-calcium-wave-patterns-in-rat-ventricular-myocytes
#20
Michal Cagalinec, Dusan Chorvat, Anton Mateasik, Ljuba Bacharova
No abstract text is available yet for this article.
May 2007: Journal of Cellular and Molecular Medicine
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