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Voltage Mapping

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https://read.qxmd.com/read/32084220/feasibility-of-selective-cardiac-ventricular-electroporation
#1
Alan Sugrue, Vaibhav R Vaidya, Christopher Livia, Deepak Padmanabhan, Anas Abudan, Ameesh Isath, Tyra Witt, Christopher V DeSimone, Paul Stalboerger, Suraj Kapa, Samuel J Asirvatham, Christopher J McLeod
INTRODUCTION: The application of brief high voltage electrical pulses to tissue can lead to an irreversible or reversible electroporation effect in a cell-specific manner. In the management of ventricular arrhythmias, the ability to target different tissue types, specifically cardiac conduction tissue (His-Purkinje System) vs. cardiac myocardium would be advantageous. We hypothesize that pulsed electric fields (PEFs) can be applied safely to the beating heart through a catheter-based approach, and we tested whether the superficial Purkinje cells can be targeted with PEFs without injury to underlying myocardial tissue...
2020: PloS One
https://read.qxmd.com/read/32083173/dissociate-lattice-oxygen-redox-reactions-from-capacity-and-voltage-drops-of-battery-electrodes
#2
Jinpeng Wu, Zengqing Zhuo, Xiaohui Rong, Kehua Dai, Zachary Lebens-Higgins, Shawn Sallis, Feng Pan, Louis F J Piper, Gao Liu, Yi-de Chuang, Zahid Hussain, Qinghao Li, Rong Zeng, Zhi-Xun Shen, Wanli Yang
The oxygen redox (OR) activity is conventionally considered detrimental to the stability and kinetics of batteries. However, OR reactions are often confused by irreversible oxygen oxidation. Here, based on high-efficiency mapping of resonant inelastic x-ray scattering of both the transition metal and oxygen, we distinguish the lattice OR in Na0.6 [Li0.2 Mn0.8 ]O2 and compare it with Na2/3 [Mg1/3 Mn2/3 ]O2 . Both systems display strong lattice OR activities but with distinct electrochemical stability. The comparison shows that the substantial capacity drop in Na0...
February 2020: Science Advances
https://read.qxmd.com/read/32081219/validation-of-dipole-density-mapping-during-atrial-fibrillation-and-sinus-rhythm-in-human-left-atrium
#3
Rui Shi, Paras Parikh, Zhong Chen, Nathan Angel, Mark Norman, Wajid Hussain, Charlie Butcher, Shouvik Haldar, David G Jones, Omar Riad, Vias Markides, Tom Wong
OBJECTIVES: This study sought to validate the accuracy of noncontact electrograms against contact electrograms in the left atrium during sinus rhythm (SR) and atrial fibrillation (AF). BACKGROUND: Noncontact mapping offers the opportunity to assess global cardiac activation in the chamber of interest. A novel noncontact mapping system, which records intracardiac voltage to derive cellular charge sources (dipole density), allows real-time mapping of AF to guide ablation...
February 2020: JACC. Clinical Electrophysiology
https://read.qxmd.com/read/32071639/utility-of-directional-high-density-mapping-catheter-advisor-tm-hd-grid-in-complex-scar-related-atrial-tachycardia
#4
Vern Hsen Tan, Murphy Zhiyuan Lyu, Peter Carlo Tan, Loo Chin Wong, Colin Yeo, Kelvin Cheok Keng Wong
Mapping of scar-related atrial tachycardias (AT) can be challenging even with the use of high-density (HD) mapping catheter. AdvisorTM HD Grid is the only directional HD mapping catheter which not only identify local electrical signal but more importantly capture the direction of wave front propagation especially in low voltage zone. Accordingly, we present a case of complex scar-related AT with the use of AdvisorTM HD Grid which showed clear fractionated signal at isthmus area as compare to the absence of signal on ablation catheter at the same area despite adequate contact force...
February 2020: Journal of Arrhythmia
https://read.qxmd.com/read/32054938/connexin43-expression-in-bone-marrow-derived-cells-contributes-to-the-electrophysiological-properties-of-cardiac-scar-tissue
#5
Carolina Vasquez, Valeria Mezzano, Newman Kessler, Freja Swardh, Desiree Ernestad, Vanessa M Mahoney, John Hanna, Gregory E Morley
Cardiac pathologies associated with arrhythmic activity are often accompanied by inflammation. The contribution of inflammatory cells to the electrophysiological properties of injured myocardium is unknown. Myocardial scar cell types and intercellular contacts were analyzed using a three-dimensional reconstruction from serial blockface scanning electron microscopy data. Three distinct cell populations were identified: inflammatory, fibroblastic and endocardial cells. While individual fibroblastic cells interface with a greater number of cells, inflammatory cells have the largest contact area suggesting a role in establishing intercellular electrical connections in scar tissue...
February 13, 2020: Scientific Reports
https://read.qxmd.com/read/32052469/improving-the-ct-140-kvp-to-pet-511-kev-conversion-in-pet-mr-hardware-component-attenuation-correction
#6
Mark Oehmigen, Maike E Lindemann, Lutz Tellmann, Titus Lanz, Harald H Quick
PURPOSE: Today, attenuation correction (AC) of PET/MR hardware components is performed by using an established method from PET/CT hybrid imaging. As shown in previous studies, the established mathematical conversion from CT to PET attenuation coefficients may, however, lead to incorrect results in PET quantification when applied to AC of hardware components in PET/MR. The purpose of this study is to systematically investigate the attenuating properties of various materials and electronic components frequently used in the context of PET/MR hybrid imaging...
February 12, 2020: Medical Physics
https://read.qxmd.com/read/32051487/in-situ-procedure-for-high-efficiency-computational-modeling-of-atrial-fibrillation-reflecting-personal-anatomy-fiber-orientation-fibrosis-and-electrophysiology
#7
Byounghyun Lim, Jaehyeok Kim, Minki Hwang, Jun-Seop Song, Jung Ki Lee, Hee-Tae Yu, Tae-Hoon Kim, Jae-Sun Uhm, Boyoung Joung, Moon-Hyung Lee, Hui-Nam Pak
We previously reported the feasibility and efficacy of a simulation-guided clinical catheter ablation of atrial fibrillation (AF) in an in-silico AF model. We developed a highly efficient realistic AF model reflecting the patient endocardial voltage and local conduction and tested its clinical feasibility. We acquired > 500 endocardial bipolar electrograms during right atrial pacing at the beginning of the AF ablation procedures. Based on the clinical bipolar electrograms, we generated simulated voltage maps by applying fibrosis and local activation maps adjusted for the fiber orientation...
February 12, 2020: Scientific Reports
https://read.qxmd.com/read/32051234/a-compact-quadrupole-orbitrap-mass-spectrometer-with-faims-interface-improves-proteome-coverage-in-short-lc-gradients
#8
Dorte B Bekker-Jensen, Ana Martinez-Val, Sophia Steigerwald, Patrick Leopold Rüther, Kyle L Fort, Tabiwang N Arrey, Alexander Harder, Alexander A Makarov, Jesper V Olsen
State-of-the-art proteomics-grade mass spectrometers can measure peptide precursors and their fragments with ppm mass accuracy at sequencing speeds of tens of peptides per second with attomolar sensitivity. Here we describe a compact and robust quadrupole-orbitrap mass spectrometer equipped with a front-end High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) Interface. The performance of the Orbitrap Exploris 480 mass spectrometer is evaluated in data-dependent acquisition (DDA) and data-independent acquisition (DIA) modes in combination with FAIMS...
February 12, 2020: Molecular & Cellular Proteomics: MCP
https://read.qxmd.com/read/32048774/computed-tomography-derived-left-atrial-volume-index-gender-and-age-to-predict-the-presence-and-the-extent-of-left-atrial-low-voltage-zones-in-patients-with-atrial-fibrillation-the-zaq-score
#9
Gabriele D'Ambrosio, Silvio Romano, Obaida Alothman, Markus Frommhold, Georgi Borisov, Mohammad El Garhy, Karam Issa, Maria Penco, Santi Raffa, Johann Christoph Geller
BACKGROUND: Pulmonary vein isolation is the cornerstone of catheter ablation in patients with atrial fibrillation (AF). However, with advanced left atrial (LA) structural changes, additional targeted catheter ablation of low voltage zones (LVZs) has produced favorable results. Therefore, with the advent of single-shot techniques, it would be helpful to predict the presence of LVZs before an ablation procedure. OBJECTIVE: We hypothesized that computed tomography-derived (CT) left atrial volume index (LAVI), in combination with other objective parameters, could be used to develop a score able to predict the presence of LVZs...
February 12, 2020: Journal of Cardiovascular Electrophysiology
https://read.qxmd.com/read/32043970/organic-electrochemical-transistor-arrays-for-real-time-mapping-of-evoked-neurotransmitter-release-in-vivo
#10
Kai Xie, Naixiang Wang, Xudong Lin, Zixun Wang, Xi Zhao, Peilin Fang, Haibing Yue, Junhwi Kim, Jing Luo, Shaoyang Cui, Feng Yan, Peng Shi
Though neurotransmitters are essential in neural signal transmission, techniques for in vivo analysis are still limited. Here, we describe an organic electrochemical transistor array (OECT-array) technique for monitoring catecholamine neurotransmitters (CA-NTs) in rat brains. The OECT-array is an active sensor with intrinsic amplification capability, allowing real-time and direct readout of transient CA-NT release with a sensitivity of nanomolar range and a temporal resolution of several milliseconds. The device has a working voltage lower than half of that typically used in a prevalent cyclic voltammetry measurement, and operates continuously in vivo for hours without significant signal drift, which is inaccessible for existing methods...
February 11, 2020: ELife
https://read.qxmd.com/read/32041227/ni-2-p-rgo-nf-nanosheets-as-a-bifunctional-high-performance-electrocatalyst-for-water-splitting
#11
Jinyu Huang, Feifei Li, Baozhong Liu, Peng Zhang
The hydrogen generated via the water splitting method is restricted by the high level of theoretical potential exhibited by the anode. The work focuses on synthesizing a bifunctional catalyst with a high efficiency, that is, a nickel phosphide doped with the reduced graphene oxide nanosheets supported on the Ni foam (Ni2 P/rGO/NF), via the hydrothermal approach together with the calcination approach specific to the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The Raman, X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscope (TEM), Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HRTEM), as well as elemental mapping, are adopted to study the composition and morphology possessed by Ni2 P/rGO/NF...
February 6, 2020: Materials
https://read.qxmd.com/read/32037614/electrophysiological-findings-during-af-re-ablation-extending-from-pv-reconnection-to-sequential-bipolar-voltage-map-information
#12
Yan Huo, Mads Brix Kronborg, Utz Richter, Jianping Guo, Stefan Ulbrich, Angela M Zedda, Bettina Kirstein, Julia Mayer, Liying Pu, Judith Piorkowski, Michael Wagner, Thomas Gaspar, Christopher Piorkowski
BACKGROUND: Left atrial substrate modification targeting low voltage zones (LVZ) is an ablation strategy that - in addition to pulmonary vein isolation (PVI) - tries to eliminate arrhythmogenic mechanisms harbored in such tissue. Electrophysiological findings at re-ablation include (i) PV re-connection, (ii) reconnection over previous substrate ablation, and (iii) de-novo LVZ. OBJECTIVE: To study, prevalence and contribution of these arrhythmogenic electrophysiological entities in patients with AF recurrences...
February 9, 2020: Journal of Cardiovascular Electrophysiology
https://read.qxmd.com/read/32032965/resistance-switching-in-large-area-vertical-junctions-of-the-molecular-spin-crossover-complex-fe-hb-tz-3-2-on-off-ratios-and-device-stability
#13
Yuteng Zhang, Isabelle Séguy, Karl Ridier, Victoria Shalabaeva, Mario Piedrahita-Bello, Aurelian Rotaru, Lionel Salmon, Gabor Molnar, Azzedine Bousseksou
Multilayer crossbar junctions composed of ITO/[Fe(HB(1,2,4-triazol-1-yl)3)2]/M (with M = Al or Ca) were fabricated and investigated for their resistance switching properties. Current-voltage-temperature maps revealed ON/OFF resistance ratios as high as 400, with the ON and OFF states defined, respectively, as the low-resistance, low spin state and the high-resistance, high spin state of the spin crossover layer. Similar results were obtained with Al and Ca cathodes indicating that the charge transport in the insulating spin crossover film is at the origin of the resistance switching instead of electron injection at the electrodes...
February 7, 2020: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://read.qxmd.com/read/32013861/transcriptomic-profiles-of-dunaliella-salina-in-response-to-hypersaline-stress
#14
Qinghua He, Yaqiu Lin, Hong Tan, Yu Zhou, Yongli Wen, Jiajia Gan, Ruiwen Li, Qinglian Zhang
BACKGROUND: Dunaliella salina is a good model organism for studying salt stress. In order to have a global understanding of the expression profiles of Dunaliella salina in response to hypersaline stress, we performed quantitative transcriptomic analysis of Dunaliella salina under hypersaline stress (2.5 M NaCl) of different time duration by the second and third generation sequencing method. RESULTS: Functional enrichment of the up-regulated genes was used to analyze the expression profiles...
February 3, 2020: BMC Genomics
https://read.qxmd.com/read/31997675/differential-localization-of-voltage-gated-potassium-channels-during-drosophila-metamorphosis
#15
Jan Werner, Jashar Arian, Ida Bernhardt, Stefanie Ryglewski, Carsten Duch
Neuronal excitability is determined by the combination of different ion channels and their sub-neuronal localization. This study utilizes protein trap fly strains with endogenously tagged channels to analyze the spatial expression patterns of the four Shaker-related voltage-gated potassium channels, Kv 1-4, in the larval, pupal, and adult Drosophila ventral nerve cord. We find that all four channels (Shaker, Kv 1; Shab, Kv 2; Shaw, Kv 3; and Shal, Kv 4) each show different spatial expression patterns in the Drosophila ventral nerve cord and are predominantly targeted to different sub-neuronal compartments...
January 30, 2020: Journal of Neurogenetics
https://read.qxmd.com/read/31990570/nanoscale-mapping-of-the-double-layer-potential-at-the-graphene-electrolyte-interface
#16
Evgheni Strelcov, Christopher Arble, Hongxuan Guo, Brian D Hoskins, Alexander Yulaev, Ivan V Vlassiouk, Nikolai B Zhitenev, Alexander Tselev, Andrei Kolmakov
The electrical double layer (EDL) governs the operation of multiple electrochemical devices, determines reaction potentials, and conditions ion transport through cellular membranes in living organisms. The few existing methods of EDL probing have low spatial resolution, usually only providing spatially-averaged information. On the other hand, traditional Kelvin probe force microscopy (KPFM) is capable of mapping potential with nanoscale lateral resolution, but cannot be used in electrolytes with concentrations higher than several mmol/L...
January 28, 2020: Nano Letters
https://read.qxmd.com/read/31989818/electric-field-and-current-induced-electroforming-modes-in-nbox
#17
Sanjoy Kumar Nandi, Shimul Kanti Nath, Assaad El-Helou, Shuai Li, Thomas Ratcliff, Mutsunori Uenuma, Peter E Raad, Robert Glen Elliman
Electroforming is used to initiate the memristive response in metal/oxide/metal devices by creating a filamentary conduction path in the oxide film. Here we use a simple photoresist-based detection technique to map the spatial distribution of conductive filaments formed in Nb/NbOx/Pt devices, and correlate these with current-voltage characteristics and in-situ thermoreflectance measurements to identify distinct modes of electroforming in low and high conductivity NbOx films. In low conductivity films the filaments are randomly distributed within the oxide film, consistent with a field-induced weakest-link mechanism, while in high conductivity films they are concentrated in the center of the film...
January 28, 2020: ACS Applied Materials & Interfaces
https://read.qxmd.com/read/31985784/a-novel-multielectrode-catheter-for-high-density-ventricular-mapping-electrogram-characterization-and-utility-for-scar-mapping
#18
Michael Barkagan, Jakub Sroubek, Ayelet Shapira-Daniels, Hagai Yavin, Jihye Jang, Reza Nezafat, Elad Anter
AIMS: Multielectrode mapping catheters can be advantageous for identifying surviving myocardial bundles in scar. This study aimed to evaluate the utility of a new multielectrode catheter with increased number of small and closely spaced electrodes for mapping ventricles with healed infarction. METHODS AND RESULTS: In 12 swine (four healthy and eight with infarction), the left ventricle was mapped with investigational (OctarayTM) and standard (PentarayTM) multielectrode mapping catheters...
January 27, 2020: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://read.qxmd.com/read/31980605/impaired-neuronal-sodium-channels-cause-intranodal-conduction-failure-and-reentrant-arrhythmias-in-human-sinoatrial-node
#19
Ning Li, Anuradha Kalyanasundaram, Brian J Hansen, Esthela J Artiga, Roshan Sharma, Suhaib H Abudulwahed, Katelynn M Helfrich, Galina Rozenberg, Pei-Jung Wu, Stanislav Zakharkin, Sandor Gyorke, Paul Ml Janssen, Bryan A Whitson, Nahush A Mokadam, Brandon J Biesiadecki, Federica Accornero, John D Hummel, Peter J Mohler, Halina Dobrzynski, Jichao Zhao, Vadim V Fedorov
Mechanisms for human sinoatrial node (SAN) dysfunction are poorly understood and whether human SAN excitability requires voltage-gated sodium channels (Nav) remains controversial. Here, we report that neuronal (n)Nav blockade and selective nNav1.6 blockade during high-resolution optical mapping in explanted human hearts depress intranodal SAN conduction, which worsens during autonomic stimulation and overdrive suppression to conduction failure. Partial cardiac (c)Nav blockade further impairs automaticity and intranodal conduction, leading to beat-to-beat variability and reentry...
January 24, 2020: Nature Communications
https://read.qxmd.com/read/31978914/high-resolution-transcranial-acoustoelectric-imaging-of-current-densities-from-a-directional-deep-brain-stimulator
#20
Chet Preston, Alexander Alvarez, Andres Barragan, Jennifer Becker, Willard Kasoff, Russell Witte
OBJECTIVE: New innovations in deep brain stimulation (DBS) enable directional current steering - allowing more precise electrical stimulation of the targeted brain structures for Parkinson's disease, essential tremor and other neurological disorders. While intra-operative navigation through MRI or CT approaches millimeter accuracy for placing the DBS leads, no existing modality provides feedback of the currents as they spread from the contacts through the brain tissue. In this study, we investigate transcranial acoustoelectric imaging (tAEI) as a new modality to non-invasively image and characterize current produced from a directional DBS lead...
January 24, 2020: Journal of Neural Engineering
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