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Voltage Mapping

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https://www.readbyqxmd.com/read/28432503/high-voltage-zones-within-the-pulmonary-vein-antra-major-determinants-of-acute-pulmonary-vein-reconnections-after-atrial-fibrillation-ablation
#1
Koichi Nagashima, Ichiro Watanabe, Yasuo Okumura, Kazuki Iso, Keiko Takahashi, Ryuta Watanabe, Masaru Arai, Sayaka Kurokawa, Toshiko Nakai, Kimie Ohkubo, Shunichi Yoda, Atsushi Hirayama
PURPOSE: Recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) is mainly due to PV reconnections. Patient-specific tissue characteristics that may contribute remain unidentified. This study aimed to assess the relationship between the bipolar electrogram voltage amplitudes recorded from the PV-left atrial (LA) junction and acute PV reconnection sites. METHODS: Three-dimensional LA voltage maps created before an extensive encircling PVI in 47 AF patients (31 men; mean age 62 ± 11 years) were examined for an association between the EGM voltage amplitude recorded from the PV-LA junction and acute post-PVI PV reconnections (spontaneous PV reconnections and/or ATP-provoked dormant PV conduction)...
April 21, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28430892/anti-arrhythmic-potential-of-the-late-sodium-current-inhibitor-gs-458967-in-murine-scn5a-1798insd-and-human-scn5a-1795insd-ipsc-derived-cardiomyocytes
#2
Vincent Portero, Simona Casini, Maaike Hoekstra, Arie O Verkerk, Isabella Mengarelli, Luiz Belardinelli, Sridharan Rajamani, Arthur A M Wilde, Connie R Bezzina, Marieke W Veldkamp, Carol Ann Remme
AIM: Selective inhibition of cardiac late sodium current (INaL) is an emerging target in the treatment of ventricular arrhythmias. We investigated the electrophysiological effects of GS-458967 (GS967), a potent, selective inhibitor of INaL, in an overlap syndrome model of both gain and loss of sodium channel function, comprising cardiomyocytes derived from both human SCN5A-1795insD+/- induced pluripotent stem cells (hiPSC-CMs) and mice carrying the homologous mutation Scn5a-1798insD+/-...
April 18, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28430225/phase-shifting-by-wavelength-modulation-in-a-cube-beam-splitter-interferometer
#3
Uriel Rivera-Ortega
A low-cost and fully automated process for phase-shifting interferometry by continuously changing the input voltage of a laser diode under the scheme of a cube beam splitter interferometer, performing as a two-window common-path interferometric setup, is presented. The input signal of a laser diode is controlled by a data acquisition device which permits a change in its wavelength according to its tunability features. The automation and data analysis is done using LabVIEW in combination with MATLAB. By using the Carré algorithm, the phase map is obtained...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28419208/interhemispheric-synchrony-of-spontaneous-cortical-states-at-the-cortical-column-level
#4
Kazunori O'Hashi, Tomer Fekete, Thomas Deneux, Rina Hildesheim, Cees van Leeuwen, Amiram Grinvald
In cat early visual cortex, neural activity patterns resembling evoked orientation maps emerge spontaneously under anesthesia. To test if such patterns are synchronized between hemispheres, we performed bilateral imaging in anesthetized cats using a new improved voltage-sensitive dye. We observed map-like activity patterns spanning early visual cortex in both hemispheres simultaneously. Patterns virtually identical to maps associated with the cardinal and oblique orientations emerged as leading principal components of the spontaneous fluctuations, and the strength of transient orientation states was correlated with their duration, providing evidence that these maps are transiently attracting states...
April 13, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28417593/anomalous-resistance-hysteresis-in-oxide-reram-oxygen-evolution-and-reincorporation-revealed-by-in-situ-tem
#5
David Cooper, Christoph Baeumer, Nicolas Bernier, Astrid Marchewka, Camilla La Torre, Rafal E Dunin-Borkowski, Stephan Menzel, Rainer Waser, Regina Dittmann
The control and rational design of redox-based memristive devices, which are highly attractive candidates for next-generation nonvolatile memory and logic applications, is complicated by competing and poorly understood switching mechanisms, which can result in two coexisting resistance hystereses that have opposite voltage polarity. These competing processes can be defined as regular and anomalous resistive switching. Despite significant characterization efforts, the complex nanoscale redox processes that drive anomalous resistive switching and their implications for current transport remain poorly understood...
April 18, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28407062/voltage-gradient-mapping-and-electrophysiologically-guided-cryoablation-in-children-with-avnrt
#6
Fabrizio Drago, Irma Battipaglia, Mario Salvatore Russo, Romolo Remoli, Vincenzo Pazzano, Gino Grifoni, Greta Allegretti, Massimo Stefano Silvetti
Aims: Recently, voltage gradient mapping of Koch's triangle to find low-voltage connections, or 'voltage bridges', corresponding to the anatomic position of the slow pathway, has been introduced as a method to ablate atrioventricular nodal reentry tachycardia (AVNRT) in children. Thus, we aimed to assess the effectiveness of voltage mapping of Koch's triangle, combined with the search for the slow potential signal in 'low-voltage bridges', to guide cryoablation of AVNRT in children. Methods and results: From June 2015 to May 2016, 35 consecutive paediatric patients (mean age 12...
April 12, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28397709/ion-damage-free-planarization-or-shallow-angle-sectioning-of-solar-cells-for-mapping-grain-orientation-and-nanoscale-photovoltaic-properties
#7
Yasemin Kutes, Justin Luria, Yu Sun, Andrew Moore, Brandon A Aguirre, Jose L Cruz-Campa, Mark Aindow, David Zubia, Bryan D Huey
Ion beam milling is the most common modern method for preparing specific features for microscopic analysis, even though concomitant ion implantation and amorphization remain persistent challenges, particularly as they often modify materials properties of interest. Atomic force microscopy (AFM), on the other hand, can mechanically mill specific nanoscale regions in plan-view without chemical or high energy ion damage, due to its resolution, directionality, and fine load control. As an example, AFM-nanomilling (AFM-NM) is implemented for top-down planarization of polycrystalline CdTe thin film solar cells, with a resulting decrease in the root mean square (RMS) roughness by an order of magnitude, even better than for a low incidence FIB polished surface...
May 5, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28396753/catheter-ablation-of-hemodynamically-unstable-ventricular-tachycardia-in-ischemic-cardiomyopathy-using-high-resolution-mapping
#8
Lukas Kaiser, Mario Jularic, Ruken Özge Akbulak, Jana Nührich, Stephan Willems, Christian Meyer
Catheter ablation is a recommended therapy option for ventricular tachycardia (VT). The antegrade transseptal approach for targeting VT with left ventricular origin is feasible with the high-resolution basket catheter. High-resolution mapping offers the potential to quickly acquire detailed voltage and activation maps. This may help to identify the crucial VT-substrate even in patients with huge scar areas and hemodynamically unstable VT.
April 2017: Clinical Case Reports
https://www.readbyqxmd.com/read/28396346/photoaffinity-labeling-with-cholesterol-analogues-precisely-maps-a-cholesterol-binding-site-in-voltage-dependent-anion-channel-1
#9
Melissa M Budelier, Wayland Wl Cheng, Lucie Bergdoll, Zi-Wei Chen, James W Janetka, Jeff Abramson, Kathiresan Krishnan, Laurel Mydock-McGrane, Douglas F Covey, Julian P Whitelegge, Alex S Evers
Voltage-dependent anion channel-1 (VDAC1) is a highly regulated β-barrel membrane protein that mediates transport of ions and metabolites between the mitochondria and cytosol of the cell. VDAC1 co-purifies with cholesterol and is functionally regulated by cholesterol, among other endogenous lipids. Molecular modeling studies based on NMR observations have suggested five cholesterol-binding sites in VDAC1, but direct experimental evidence for these sites is lacking. Here, to determine the sites of cholesterol binding, we photolabeled purified mouse VDAC1 (mVDAC1) with photoactivatable cholesterol analogues and analyzed the photolabeled sites with both top-down mass spectrometry (MS), and bottom-up MS paired with a clickable, stable isotope labeled tag, FLI-tag...
April 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28395022/optogenetic-manipulation-of-anatomical-re-entry-by-light-guided-generation-of-a-reversible-local-conduction-block
#10
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/28387462/identification-and-electrophysiological-characterization-of-early-left-atrial-structural-remodeling-as-a-predictor-for-atrial-fibrillation-recurrence-after-pulmonary-vein-isolation
#11
Atsuhiko Yagishita, Dina Sparano, Ivan Cakulev, J Rod Gimbel, Timothy Phelan, Hossam Mustafa, Samer De Oliveira, Judith Mackall, Mauricio Arruda
BACKGROUND: Voltage-guided substrate ablation following pulmonary vein isolation (PVI) improves atrial fibrillation (AF) ablation outcomes. However, by setting upper voltage cutoff of 0.5 mV during sinus rhythm (SR) to guided substrate ablation using electroanatomic voltage mapping (EAVM), mildly affected low voltage area (maLVA) may be undetected. We sought to determine the optimal bipolar voltage cutoff to identify maLVA, its electrogram complexity, and the implication on ablation outcome...
April 7, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28381014/aberration-control-in-adaptive-optics-a-numerical-study-of-arbitrarily-deformable-liquid-lenses
#12
N C Lima, K Mishra, F Mugele
By means of numerical simulations, using a computational fluid dynamics software together with an optical ray tracing analysis platform, we show that we can tune various optical aberrations by electrically manipulating the shape of liquid lenses using one hundred individually addressable electrodes. To demonstrate the flexibility of our design, we define electrode patterns based on specific Zernike modes and show that aspherical, cylindrical and decentered shapes of liquid lenses can be produced. Using different voltages, we evaluate the tuning range of spherical aberration (Z11), astigmatism (Z5 and Z6) and coma (Z7), while a hydrostatic pressure is applied to control the average curvature of a microlens with a diameter of 1mm...
March 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28371837/characterization-of-the-arrhythmogenic-substrate-in-patients-with-arrhythmogenic-right-ventricular-cardiomyopathy-undergoing-ventricular-tachycardia-ablation
#13
Senthil Kirubakaran, Caterina Bisceglia, John Silberbauer, Teresa Oloriz, Giulia Santagostino, Miki Yamase, Giuseppe Maccabelli, Nicola Trevisi, Paolo Della Bella
Aims: Arrhythmogenic right ventricular (RV) cardiomyopathy (ARVC) is associated with ventricular arrhythmias, even without RV structural disease. We aimed to characterize the RV substrate using electroanatomical mapping and to define outcomes following ventricular tachycardia (VT) ablation in patients with and without RV structural abnormalities. Methods and results: Twenty-nine patients with definite or suspected ARVC undergoing VT ablation were classified as 'electrical' and 'structural' cardiomyopathy based on the absence or presence of major structural criteria...
March 20, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28359670/electron-beam-induced-current-and-active-secondary-electron-voltage-contrast-with-aberration-corrected-electron-probes
#14
Myung-Geun Han, Joseph A Garlow, Matthew S J Marshall, Amanda L Tiano, Stanislaus S Wong, Sang-Wook Cheong, Frederick J Walker, Charles H Ahn, Yimei Zhu
The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively...
March 23, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28344442/voltage-directed-cavo-tricuspid-isthmus-ablation-using-a-novel-ablation-catheter-mapping-technology-in-a-myotonic-dystrophy-type-i-patient
#15
Vincenzo Russo, Anna Rago, Andrea Antonio Papa, Federica Di Meo, Carmine Ciardiello, Giovanni Cimmino, Gerardo Nigro
A successful case of maximum voltage-directed cavo-tricuspid isthmus (CTI) ablation using a novel ablation catheter mapping technology in a myotonic dystrophy type I (DM1) patient is reported. The patient complained recurrent episodes of atrial flutter, revealed by the atrio-ventricular electrograms analysis during the routine pacemaker controls.
October 2016: Acta Myologica: Myopathies and Cardiomyopathies: Official Journal of the Mediterranean Society of Myology
https://www.readbyqxmd.com/read/28340110/peri-mitral-atrial-flutter-personalized-ablation-strategy-based-on-arrhythmogenic-substrate
#16
Jinbo Yu, Kai Chen, Bing Yang, Fengxiang Zhang, Weizhu Ju, Hongwu Chen, Gang Yang, Mingfang Li, Benqi Wang, Kai Gu, Feifan Ouyang, Siew Yen Ho, Sunny Po, Minglong Chen
Aims: The aim of this study is to characterize the arrhythmogenic substrate for peri-mitral atrial flutter (PMAFL), thereby determining a personalized ablation strategy to treat PMAFL. Methods and results: Thirty-six consecutive PMAFL patients (mean age: 63.8 ± 11.3, 23 males) underwent detailed three-dimensional electroanatomic mapping in left atrium (LA). The LA was divided into septal-anterior wall (SAW), posterior inferior wall (PIW), and mitral isthmus (MI) region, respectively...
March 1, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28339804/intra-cardiac-and-peripheral-levels-of-biochemical-markers-of-fibrosis-in-patients-undergoing-catheter-ablation-for-atrial-fibrillation
#17
Gordon A Begg, Rashed Karim, Tobias Oesterlein, Lee N Graham, Andrew J Hogarth, Stephen P Page, Christopher B Pepper, Kawal Rhode, Gregory Y H Lip, Arun V Holden, Sven Plein, Muzahir H Tayebjee
Aims: Measurement of circulating biomarkers of fibrosis may have a role in selecting patients and treatment strategy for catheter ablation. Pro-collagen type III N-terminal pro-peptide (PIIINP), C-telopeptide of type I collagen (ICTP), fibroblast growth factor 23 (FGF-23), and galectin 3 (gal-3) have all been suggested as possible biomarkers for this indication, but studies assessing whether peripheral levels reflect intra-cardiac levels are scarce. Methods and results: We studied 93 patients undergoing ablation for paroxysmal atrial fibrillation (AF) (n = 63) or non-paroxysmal AF (n = 30)...
February 27, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28334181/uncovering-the-spatial-profile-of-contour-integration-from-fixational-saccades-evidence-for-widespread-processing-in-v1
#18
Ariel Gilad, Roy Oz, Hamutal Slovin
During contour integration, neuronal populations in the primary visual cortex (V1) enhance their responses to the contour while suppressing their responses to the noisy background. However, the spatial extent and profile of these responses are not fully understood. To investigate this question, 2 monkeys were trained on a contour detection task while we measured population responses in V1 using voltage-sensitive dyes. During stimulus presentation the animals made few fixational saccades, and we used their changing gaze position to image and analyze neuronal responses from large part of the stimulus, encoding multiple contour/background elements...
October 5, 2016: Cerebral Cortex
https://www.readbyqxmd.com/read/28315127/inherited-ventricular-arrhythmias-the-role-of-the-multi-subunit-structure-of-the-l-type-calcium-channel-complex
#19
Julie Briot, Marie-Philippe Tétreault, Benoîte Bourdin, Lucie Parent
The normal heartbeat is conditioned by transient increases in the intracellular free Ca(2+) concentration. Ca(2+) influx in cardiomyocytes is regulated by the activity of the heteromeric L-type voltage-activated CaV1.2 channel. A complex network of interactions between the different proteins forming the ion channel supports the kinetics and the activation gating of the Ca(2+) influx. Alterations in the biophysical and biochemical properties or in the biogenesis in any of these proteins can lead to serious disturbances in the cardiac rhythm...
March 18, 2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28269147/electrocardiogram-reconstruction-from-high-resolution-voltage-optical-mapping
#20
Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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