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Voltage Mapping

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https://www.readbyqxmd.com/read/29779525/geometrical-constraint-of-sources-in-noninvasive-localization-of-premature-ventricular-contractions
#1
Jana Svehlikova, Michal Teplan, Milan Tysler
The inverse problem of electrocardiography for localization of a premature ventricular contraction (PVC) origin was solved and compared for three types of the equivalent cardiac electrical generator: transmembrane voltages, epicardial potentials, and dipoles. Instead of regularization methods usually used for the ill-posed inverse problems an assumption of a single point source representative of the heart generator was applied to the solution as a geometrical constraint. Body surface potential maps were simulated from eight modeled origins of the PVC in the heart model...
May 2018: Journal of Electrocardiology
https://www.readbyqxmd.com/read/29778719/effect-of-heptanol-and-ethanol-on-excitation-wave-propagation-in-a-neonatal-rat-ventricular-myocyte-monolayer
#2
A D Podgurskaya, V A Tsvelaya, S R Frolova, I Y Kalita, N N Kudryashova, K I Agladze
In this work, the action of heptanol and ethanol was investigated in a two-dimensional (2D) model of cardiac tissue: the neonatal rat ventricular myocyte monolayer. Heptanol is known in electrophysiology as a gap junction uncoupler but may also inhibit voltage-gated ionic channels. Ethanol is often associated with the occurrence of arrhythmias. These substances influence sodium, calcium, and potassium channels, but the complete mechanism of action of heptanol and ethanol remains unknown. The optical mapping method was used to measure conduction velocities (CVs) in concentrations of 0...
May 17, 2018: Toxicology in Vitro: An International Journal Published in Association with BIBRA
https://www.readbyqxmd.com/read/29769223/comprehensive-multicenter-study-of-the-common-isthmus-in-post-atrial-fibrillation-ablation-multiple-loop-atrial-tachycardia
#3
Masateru Takigawa, Nicolas Derval, Philippe Maury, Ruairidh Martin, Arnaud Denis, Shinsuke Miyazaki, Seigo Yamashita, Antonio Frontera, Konstantinos Vlachos, Takeshi Kitamura, Ghassen Cheniti, Greégoire Massoullieé, Nathaniel Thompson, Claire A Martin, Michael Wolf, Xavier Pillois, Josselin Duchateau, Nicolas Klotz, Alexandre Duparc, Anne Rollin, Thomas Pambrun, Frédéric Sacher, Hubert Cochet, Mélèze Hocini, Michel Haiïssaguerre, Pierre Jaiïs
BACKGROUND: Characteristics of multiple-loop atrial tachycardia (AT) circuits have never precisely examined. METHODS: In 193 consecutive post-atrial fibrillation ablation patients with AT, 44 multiple-loop ATs including 42 dual-loop AT and 2 triple-loop AT in 41 (21.2%) were diagnosed with the high-resolution mapping system and analyzed off-line. RESULTS: In dual-loop ATs, 3 types were identified: type M, a combination of 2 anatomic macroreentrant ATs (AMATs) in 19 (43...
June 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29769222/transient-outward-k-current-i-to-underlies-the-right-ventricular-initiation-of-polymorphic-ventricular-tachycardia-in-a-transgenic-rabbit-model-of-long-qt-syndrome-type-1
#4
Bum-Rak Choi, Weiyan Li, Dmitry Terentyev, Anatoli Y Kabakov, Mingwang Zhong, Colin M Rees, Radmila Terentyeva, Tae Yun Kim, Zhilin Qu, Xuwen Peng, Alain Karma, Gideon Koren
BACKGROUND: Sudden death in long-QT syndrome type 1 (LQT1), an inherited disease caused by loss-of-function mutations in KCNQ1, is triggered by early afterdepolarizations (EADs) that initiate polymorphic ventricular tachycardia (pVT). We investigated ionic mechanisms that underlie pVT in LQT1 using a transgenic rabbit model of LQT1. METHODS: Optical mapping, cellular patch clamping, and computer modeling were used to elucidate the mechanisms of EADs in transgenic LQT1 rabbits...
June 2018: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29761692/visualizing-the-zero-potential-line-of-bipolar-electrodes-with-arbitrary-geometry
#5
Meng Li, Shasha Liu, Yingyan Jiang, Wei Wang
In a typical bipolar electrochemistry (BPE) configuration, voltage applied between the two driving electrodes induced a potential drop through solution filled in the microchannel, resulting in interfacial potential difference between solution and BPE varied along the BPE. In the present work, we employed a recently-developed plasmonic imaging technique to map the distribution of surface potential of bipolar electrodes with various geometries including round, triangle, hexagon, star and rhombus shapes under non-faradaic charging process, from which the line of zero potential (LZP) was visualized and determined...
May 15, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29759722/new-insights-into-an-old-arrhythmia-high-resolution-mapping-demonstrates-conduction-and-substrate-variability-in-right-atrial-macro-re-entrant-tachycardia
#6
Bhupesh Pathik, Geoffrey Lee, Frédéric Sacher, Pierre Jaïs, Grégoire Massoullié, Nicolas Derval, Matthew G Bates, Jonathan Lipton, Stephen Joseph, Joseph Morton, Paul Sparks, Peter Kistler, Jonathan M Kalman
OBJECTIVES: Using high-resolution 3-dimensional (3D) mapping, the aim of this study was to further characterize right atrial macro-re-entrant tachycardias and answer unresolved questions in the understanding of this arrhythmia. BACKGROUND: Despite advances in understanding of the mechanisms of right atrial macro-re-entrant tachycardias, many questions lack definitive answers. The advent of high-resolution 3D mapping provides an opportunity to gain further insights into the nature of these common circuits...
September 2017: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29759533/12-lead-electrocardiogram-to-localize-region-of-abnormal-electroanatomic-substrate-in-arrhythmogenic-right-ventricular-cardiomyopathy
#7
Cory M Tschabrunn, Haris M Haqqani, Pasquale Santangeli, Erica S Zado, Francis E Marchlinski
OBJECTIVES: The purpose of this study was to evaluate the relationship between electrocardiogram (ECG) QRS fragmentation (fQRS) and right ventricular (RV) endocardial (ENDO) and epicardial (EPI) electroanatomic substrate abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). BACKGROUND: fQRS is frequently observed in patients with ARVC and reflects delayed conduction due to RV fibrosis. METHODS: A total of 30 consecutive patients met the task force criteria for ARVC (19 men, mean age 41...
July 2017: JACC. Clinical Electrophysiology
https://www.readbyqxmd.com/read/29758301/lipid-roles-in-herg-function-and-interactions-with-drugs
#8
REVIEW
Meruyert Kudaibergenova, Laura L Perissinotti, Sergei Y Noskov
Human-ether-a-go-go-related channel (hERG) is a voltage gated potassium channel (Kv 11.1) abundantly expressed in heart and brain tissues. In addition to playing an important role in mediation of repolarizing K+ currents (IKr ) in Action Potential (AP), hERG is notorious for its propensity to interact with various medications. The drug-induced block of K+ currents across hERG channel are strongly associated with dysrhythmic conditions collectively known as drug-induced long-QT-syndrome. The recent availability of the high-resolution Cryo-EM structures for the hERG channel has provided unique opportunity to resolve structural mechanisms involved into the process of voltage-gating of hERG channels, map various roles played by components of ventricular and neuronal membranes and then to connect it to cellular pathways through which diverse chemical compounds might be affecting function of the channel...
May 11, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/29754959/human-induced-pluripotent-stem-cell-derived-cardiac-cell-sheets-expressing-genetically-encoded-voltage-indicator-for-pharmacological-and-arrhythmia-studies
#9
Naim Shaheen, Assad Shiti, Irit Huber, Rami Shinnawi, Gil Arbel, Amira Gepstein, Noga Setter, Idit Goldfracht, Amit Gruber, Snizhanna V Chorna, Lior Gepstein
Fulfilling the potential of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes for studying conduction and arrhythmogenesis requires development of multicellular models and methods for long-term repeated tissue phenotyping. We generated confluent hiPSC-derived cardiac cell sheets (hiPSC-CCSs), expressing the genetically encoded voltage indicator ArcLight. ArcLight-based optical mapping allowed generation of activation and action-potential duration (APD) maps, which were validated by mapping the same hiPSC-CCSs with the voltage-sensitive dye, Di-4-ANBDQBS...
May 7, 2018: Stem Cell Reports
https://www.readbyqxmd.com/read/29748663/direct-neurotransmitter-activation-of-voltage-gated-potassium-channels
#10
Rían W Manville, Maria Papanikolaou, Geoffrey W Abbott
Voltage-gated potassium channels KCNQ2-5 generate the M-current, which controls neuronal excitability. KCNQ2-5 subunits each harbor a high-affinity anticonvulsant drug-binding pocket containing an essential tryptophan (W265 in human KCNQ3) conserved for >500 million years, yet lacking a known physiological function. Here, phylogenetic analysis, electrostatic potential mapping, in silico docking, electrophysiology, and radioligand binding assays reveal that the anticonvulsant binding pocket evolved to accommodate endogenous neurotransmitters including γ-aminobutyric acid (GABA), which directly activates KCNQ5 and KCNQ3 via W265...
May 10, 2018: Nature Communications
https://www.readbyqxmd.com/read/29747445/a-novel-nonlinear-piezoelectric-energy-harvesting-system-based-on-linear-element-coupling-design-modeling-and-dynamic-analysis
#11
Shengxi Zhou, Bo Yan, Daniel J Inman
This paper presents a novel nonlinear piezoelectric energy harvesting system which consists of linear piezoelectric energy harvesters connected by linear springs. In principle, the presented nonlinear system can improve broadband energy harvesting efficiency where magnets are forbidden. The linear spring inevitably produces the nonlinear spring force on the connected harvesters, because of the geometrical relationship and the time-varying relative displacement between two adjacent harvesters. Therefore, the presented nonlinear system has strong nonlinear characteristics...
May 9, 2018: Sensors
https://www.readbyqxmd.com/read/29743298/coupling-between-an-electrostatic-network-and-the-zn-2-binding-site-modulates-hv1-activation
#12
Victor De La Rosa, Ashley L Bennett, Ian Scott Ramsey
The voltage sensor (VS) domain in Hv1 proton channels mediates a voltage-dependent and H+ -selective "aqueous" conductance (GAQ ) that is potently modulated by extracellular Zn2+ Although two conserved His residues are required for Zn2+ effects on GAQ gating, the atomic structure of the Zn2+ coordination site and mechanism by which extracellular Zn2+ stabilizes a closed-state conformation remain unknown. Here we use His mutagenesis to identify residues that increase Zn2+ potency and are therefore likely to participate in first solvation shell interactions with Zn2+ Experimental Zn2+ -mapping data were then used to constrain the structure of a new resting-state Hv1 model (Hv1 F)...
May 9, 2018: Journal of General Physiology
https://www.readbyqxmd.com/read/29740278/modeling-the-improved-visual-acuity-using-photodiode-based-retinal-implants-featuring-fractal-electrodes
#13
William J Watterson, Rick D Montgomery, Richard P Taylor
Electronically restoring vision to patients blinded by severe retinal degenerations is rapidly becoming a realizable feat through retinal implants. Upon receiving an implant, previously blind patients can now detect light, locate objects, and determine object motion direction. However, the restored visual acuity (VA) is still significantly below the legal blindness level (VA < 20/200). The goal of this research is to optimize the inner electrode geometry in photovoltaic subretinal implants in order to restore vision to a VA better than blindness level...
2018: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29738372/paradoxical-effects-of-sodium-calcium-exchanger-inhibition-on-torsade-de-pointes-and-early-afterdepolarization-in-a-heart-failure-rabbit-model
#14
Po-Cheng Chang, Yu-Ying Lu, Hui-Ling Lee, Shien-Fong Lin, Yen Chu, Ming-Shien Wen, Chung-Chuan Chou
Calcium homeostasis plays an important role in development of early afterdepolarizations (EADs) and torsade de pointes (TdP). The role of sodium-calcium exchanger (NCX) inhibition in genesis secondary Ca rise and EADs-TdP is still debated. Dual voltage and intracellular Ca optical mapping were conducted in 6 control and 9 failing rabbit hearts. After baseline electrophysiological and optical mapping studies, E4031 was given to simulate long QT syndrome. ORM-10103 was then administrated to examine the electrophysiological effects on EAD-TdP development...
May 3, 2018: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/29729399/high-density-mapping-and-ablation-of-concealed-low-voltage-activity-within-pulmonary-vein-antra-results-in-improved-freedom-from-atrial-fibrillation-compared-to-pulmonary-vein-isolation-alone
#15
Nathan M Segerson, Brian Lynch, Joshua Mozes, Melinda M Marks, Daniel K Noonan, David Gordon, Pierre Jais, Marcos Daccarett
BACKGROUND: Despite advancements, the goal of durable pulmonary vein isolation (PVI) in all patients undergoing ablation for atrial fibrillation (AF) remains elusive. New high density mapping allows detection of concealed low voltage signals (CLVS) that persist after PVI and may represent vulnerabilities in the lesion set. OBJECTIVE: To determine the incidence of CLVSs after PVI and the effect of CLVS ablation on outcomes. METHODS: We conducted a case control study comparing 150 patients undergoing High Density Mapping (HDM) guided PVI and subsequent CLVS mapping and ablation (39 redo, 111 de novo) against 452 historical controls undergoing traditional PVI alone...
May 2, 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29727513/unipolar-voltage-mapping-criteria-for-septal-aspect-of-right-ventricular-influence-of-aortic-root
#16
Iosif Kelesidis, Benoit Desjardins, Daniele Muser, Pasquale Santangeli, Erica S Zado, Francis E Marchlinski
INTRODUCTION: Unipolar voltage mapping through its wider "field of view" can identify substrate deeper to the endocardium on the right ventricular (RV) free wall and left ventricle. The reference value(s) for normal endocardial (ENDO) unipolar voltage (UNI) for the septal aspect of the right ventricle (RV) and the effect of the aortic root that is directly opposed to the posterior septal plane of the RV outflow tract (RVOT) have not been established. METHODS AND RESULTS: We performed detailed (185 ± 70, range 127-342 points) RV ENDO UNI maps in 9 patients without structural heart disease; 6 had magnetic resonance (MR) imaging; 5 were males; the mean age was 49 ± 11 years...
May 4, 2018: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/29726256/all-organic-high-performance-piezoelectric-nanogenerator-with-multilayer-assembled-electrospun-nanofibers-mats-for-self-powered-multifunctional-sensor
#17
Kuntal Maity, Dipankar Mandal
Rapid development of wearable electronics, piezoelectric nanogenerator (PNG) has been paid a special attention due to its sustainable and accessible energy generation. In this context, we present a simple yet highly efficient design strategy to enhance the output performance of an all organic PNG (OPNG) based on multilayer assembled electrospun poly(vinyledine fluoride) (PVDF) nanofibers (NFs) mats where vapor phase polymerized poly(3,4- ethylenedioxythiphene) (PEDOT) coated PVDF NFs are assembled as electrodes and neat PVDF NFs is utilized as an active component...
May 4, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29723806/bioelectrical-coupling-in-multicellular-domains-regulated-by-gap-junctions-a-conceptual-approach
#18
REVIEW
Javier Cervera, Alexis Pietak, Michael Levin, Salvador Mafe
We review the basic concepts involved in bioelectrically-coupled multicellular domains, focusing on the role of membrane potentials (Vmem ). In the first model, single-cell Vmem is modulated by two generic polarizing and depolarizing ion channels, while intercellular coupling is implemented via voltage-gated gap junctions. Biochemical and bioelectrical signals are integrated via a feedback loop between Vmem and the transcription and translation of a protein forming an ion channel. The effective rate constants depend on the single-cell Vmem because these potentials modulate the local concentrations of signaling molecules and ions...
April 21, 2018: Bioelectrochemistry
https://www.readbyqxmd.com/read/29723257/pharmacological-characterization-of-potent-and-selective-nav1-7-inhibitors-engineered-from-chilobrachys-jingzhao-tarantula-venom-peptide-jztx-v
#19
Bryan D Moyer, Justin K Murray, Joseph Ligutti, Kristin Andrews, Philippe Favreau, John B Jordan, Josie H Lee, Dong Liu, Jason Long, Kelvin Sham, Licheng Shi, Reto Stöcklin, Bin Wu, Ruoyuan Yin, Violeta Yu, Anruo Zou, Kaustav Biswas, Les P Miranda
Identification of voltage-gated sodium channel NaV1.7 inhibitors for chronic pain therapeutic development is an area of vigorous pursuit. In an effort to identify more potent leads compared to our previously reported GpTx-1 peptide series, electrophysiology screening of fractionated tarantula venom discovered the NaV1.7 inhibitory peptide JzTx-V from the Chinese earth tiger tarantula Chilobrachys jingzhao. The parent peptide displayed nominal selectivity over the skeletal muscle NaV1.4 channel. Attribute-based positional scan analoging identified a key Ile28Glu mutation that improved NaV1...
2018: PloS One
https://www.readbyqxmd.com/read/29722956/electrical-mapping-of-silver-nanowire-networks-a-versatile-tool-for-imaging-network-homogeneity-and-degradation-dynamics-during-failure
#20
Thomas Sannicolo, Nicolas Charvin, Lionel Flandin, Silas Kraus, Theodora D Papanastasiou, Caroline Celle, Jean-Pierre Simonato, David Munoz Rojas, Carmen Jiménez, Daniel Bellet
Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for increasing their robustness and reliability when integrated as transparent electrodes in devices. Our ability to distinguish defects, inhomogeneities, or inactive areas at the scale of the entire network is therefore a critical issue. We propose one-probe electrical mapping (1P-mapping) as a specific simple tool to study the electrical distribution in these discrete structures. 1P-mapping has allowed to show that the tortuosity of the voltage equipotential lines of AgNW networks under bias decreases with increasing network density, leading to a better electrical homogeneity...
May 3, 2018: ACS Nano
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