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Voltage Mapping

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https://www.readbyqxmd.com/read/28735424/a-novel-3d-anatomic-mapping-approach-using-multipoint-high-density-voltage-gradient-mapping-to-quickly-localize-and-terminate-typical-atrial-flutter
#1
William C Choe, Sri Sundaram, J Ryan Jordan, Nate Mullins, Charles Boorman, Austin Davies, Alex C Tiftickjian, Sunil Nath
PURPOSE: The purposes of the study were to evaluate and characterize the cavotricuspid isthmus using multipoint high density voltage gradient mapping (HD-VGM) to see if this would improve on current ablation techniques compared to standard cavotricuspid isthmus ablation techniques. METHODS: Group 1, 25 patients who underwent ablation using standard methods of 3D mapping and ablation, was compared to group 2, 33 patients undergoing ablation using HD-VGM and ablation...
July 22, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28733070/spatial-relationship-of-sites-for-atrial-fibrillation-drivers-and-atrial-tachycardia-in-patients-with-both-arrhythmias
#2
Tina Baykaner, Junaid A B Zaman, Albert J Rogers, Rachita Navara, Mahmood AlHusseini, Ryan T Borne, Shirley Park, Paul J Wang, David E Krummen, William H Sauer, Sanjiv M Narayan
INTRODUCTION: Atrial fibrillation (AF) often converts to and from atrial tachycardia (AT), but it is undefined if these rhythms are mechanistically related in such patients. We tested the hypothesis that critical sites for AT may be related to regional AF sources in patients with both rhythms, by mapping their locations and response to ablation on transitions to and from AF. METHODS: From 219 patients undergoing spatial mapping of AF prior to ablation at 3 centers, we enrolled 26 patients in whom AF converted to AT by ablation (n=19) or spontaneously (n=7; left atrial size 42±6cm, 38% persistent AF)...
July 14, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28730651/a-comparison-of-the-electrophysiologic-and-electroanatomic-characteristics-between-the-right-and-left-atrium-in-persistent-atrial-fibrillation-is-the-right-atrium-a-window-into-the-left
#3
Sandeep Prabhu, Aleksandr Voskoboinik, Alex Ja McLellan, Kah Y Peck, Bupesh Pathik, Chrishan J Nalliah, Geoff R Wong, Sonia M Azzopardi, Geoffrey Lee, Justin Mariani, Liang-Han Ling, Andrew J Taylor, Jonathan M Kalman, Peter M Kistler
INTRODUCTION: The right atrium (RA) is readily accessible; however, it is unclear whether changes in the RA are representative of the LA. We performed detailed bi-atrial electroanatomic mapping to determine the electrophysiological relationship between the atria. METHODS AND RESULTS: Consecutive patients with persistent AF underwent bi-atrial electroanatomical mapping with a contact force catheter acquiring points with a CF > 10 g prior to ablation. Points were analyzed for tissue voltage, complex electrograms, low voltage (< 0...
July 21, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28727202/influence-of-the-left-atrial-contact-areas-on-fixed-low-voltage-zones-during-atrial-fibrillation-and-sinus-rhythm-in-persistent-atrial-fibrillation
#4
Shiro Nakahara, Yuichi Hori, Naoki Nishiyama, Yasuo Okumura, Reiko Fukuda, Sayuki Kobayashi, Takaaki Komatsu, Yoshihiko Sakai, Isao Taguchi
BACKGROUND: Atrial low-voltage zones (LVZ) are suggested as important factors for maintaining persistent atrial fibrillation (PsAF). The relationship between LVZs and left atrial (LA) contact areas (CoAs) is still unclear. OBJECTIVE: To assess whether CoA regions were involved in atrial substrate properties maintaining PsAF. METHODS: A total of 50 patients with PsAF (36 long-lasting) were analyzed. Three representative CoA detection areas (ascending aorta-anterior-LA, descending aorta-left pulmonary vein antrum, and vertebrae-posterior-LA) were registered on the mapping geometry...
July 20, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28721729/impact-of-cl-doping-on-electrochemical-performance-in-orthosilicate-li2fesio4-a-dft-supported-experimental-approach
#5
Shivani Singh, Anish K Raj, Raja Sen, Priya Johari, Sagar Mitra
Safe and high capacity cathode materials are a long quest for commercial lithium-ion battery development. Among various searched cathode materials, Li2FeSiO4 has taken the attention due to optimal working voltage, high elemental abundance, and low toxicity. However, as per our understanding and observation, the electrochemical performance of this material is significantly limited by the intrinsic low electronic conductivity and slow lithium-ion diffusion, which limits the practical capacity (theoretical ~ 330 mAh g-1)...
July 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28716699/bridge-to-success-a-better-method-of-cryoablation-for-atrioventricular-nodal-reentrant-tachycardia-in-children
#6
Charitha D Reddy, Scott R Ceresnak, Kara S Motonaga, Kishor Avasarala, Christine Feller, Anthony Trela, Debra Hanisch, Anne M Dubin
BACKGROUND: Cryoablation for AVNRT is associated with higher recurrence rates than radiofrequency ablation(RF). Junctional tachycardia marks procedural success with RF, but no such indicator exists for cryoablation. OBJECTIVE: To determine the impact of voltage mapping plus longer ablation lesions on mid-term success of cryoablation for children with AVNRT. METHODS: A single-center retrospective analysis was performed of pediatric patients with AVNRT who underwent cryoablation from 2011-2015...
July 14, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28710068/gq-activated-fibroblasts-induce-cardiomyocyte-action-potential-prolongation-and-automaticity-in-a-3d-microtissue-environment
#7
Celinda M Kofron, Tae Yun Kim, Michelle E King, An Xie, Feng Feng, Elizabeth Park, Zhilin Qu, Bum-Rak Choi, Ulrike Mende
Cardiac fibroblasts (CFs) are known to regulate cardiomyocyte (CM) function in vivo and in 2D in vitro cultures. This study examined the effect of CF activation on the regulation of CM electrical activity in a 3D microtissue environment. Using a scaffold-free 3D platform with interspersed neonatal rat ventricular CMs and CFs, Gq-mediated signaling was selectively enhanced in CFs by Gαq adenoviral infection prior to co-seeding with CMs in non-adhesive hydrogels. After 3 days, the microtissues were analyzed by signaling assay, histological staining, quantitative PCR, Western blots, optical mapping with voltage- or calcium-sensitive dyes, and microelectrode recordings of CF resting membrane potential (RMPCF)...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28688443/coincidence-velocity-map-imaging-using-a-single-detector
#8
Arthur Zhao, Péter Sándor, Thomas Weinacht
We demonstrate a single-detector velocity map imaging setup which is capable of rapidly switching between coincidence and non-coincidence measurements. By rapidly switching the extraction voltages on the electrostatic lenses, both electrons and ions can be collected in coincidence with a single detector. Using a fast camera as the 2D detector avoids the saturation problem associated with traditional delay line detectors and allows for easy transitions between coincidence and non-coincidence data collection modes...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28688413/a-compact-design-for-velocity-map-imaging-of-energetic-electrons-and-ions
#9
D Schomas, N Rendler, J Krull, R Richter, M Mudrich
We present a compact design for a velocity-map imaging spectrometer for energetic electrons and ions. The standard geometry by Eppink and Parker [Rev. Sci. Instrum. 68, 3477 (1997)] is augmented by just two extended electrodes so as to realize an additional einzel lens. In this way, for a maximum electrode voltage of 7 kV, we experimentally demonstrate imaging of electrons with energies up to 65 eV. Simulations show that energy acceptances ≲270 and ≲1200 eV with an energy resolution ΔE∕E≲5% are achievable for electrode voltages ≤20 kV when using diameters of the position-sensitive detector of 42 and 78 mm, respectively...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28688410/a-new-electron-ion-coincidence-3d-momentum-imaging-method-and-its-application-in-probing-strong-field-dynamics-of-2-phenylethyl-n-n-dimethylamine
#10
Lin Fan, Suk Kyoung Lee, Yi-Jung Tu, Benoît Mignolet, David Couch, Kevin Dorney, Quynh Nguyen, Laura Wooldridge, Margaret Murnane, Françoise Remacle, H Bernhard Schlegel, Wen Li
We report the development of a new three-dimensional (3D) momentum-imaging setup based on conventional velocity map imaging to achieve the coincidence measurement of photoelectrons and photo-ions. This setup uses only one imaging detector (microchannel plates (MCP)/phosphor screen) but the voltages on electrodes are pulsed to push both electrons and ions toward the same detector. The ion-electron coincidence is achieved using two cameras to capture images of ions and electrons separately. The time-of-flight of ions and electrons are read out from MCP using a digitizer...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28688394/stereodirectional-images-of-molecules-oriented-by-a-variable-voltage-hexapolar-field-fragmentation-channels-of-2-bromobutane-electronically-excited-at-two-photolysis-wavelengths
#11
Masaaki Nakamura, Shiun-Jr Yang, King-Chuen Lin, Toshio Kasai, Dock-Chil Che, Andrea Lombardi, Federico Palazzetti, Vincenzo Aquilanti
The asymmetric-top molecule 2-bromobutane is oriented by means of a hexapole state selector; the angular distribution of the bromine atom photofragment, for the two fine-structure components, is acquired by velocity-map ion imaging. The molecular beam, spatially oriented along the time-of-flight axis, is intersected with a linearly polarized laser, whose polarization is tilted by 45° with respect to the detector surface. To obtain the mixing ratio of the perpendicular and parallel transitions, the fragment ion images and angular distributions can be appropriately simulated to give insight on the population mechanism of the specific electronic state involved at each selected excitation wavelength...
July 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28686619/rare-variants-of-small-effect-size-in-neuronal-excitability-genes-influence-clinical-outcome-in-japanese-cases-of-scn1a-truncation-positive-dravet-syndrome
#12
Michael F Hammer, Atsushi Ishii, Laurel Johnstone, Alexander Tchourbanov, Branden Lau, Ryan Sprissler, Brian Hallmark, Miao Zhang, Jin Zhou, Joseph Watkins, Shinichi Hirose
Dravet syndrome (DS) is a rare, devastating form of childhood epilepsy that is often associated with mutations in the voltage-gated sodium channel gene, SCN1A. There is considerable variability in expressivity within families, as well as among individuals carrying the same primary mutation, suggesting that clinical outcome is modulated by variants at other genes. To identify modifier gene variants that contribute to clinical outcome, we sequenced the exomes of 22 individuals at both ends of a phenotype distribution (i...
2017: PloS One
https://www.readbyqxmd.com/read/28678875/evaluation-of-the-use-of-unipolar-voltage-amplitudes-for-detection-of-myocardial-scar-assessed-by-cardiac-magnetic-resonance-imaging-in-heart-failure-patients
#13
Uyên Châu Nguyên, Francesco Maffessanti, Masih Mafi-Rad, Giulio Conte, Stef Zeemering, François Regoli, Maria Luce Caputo, Antonius M W van Stipdonk, Sebastiaan C A M Bekkers, Daniel Suerder, Tiziano Moccetti, Rolf Krause, Frits W Prinzen, Kevin Vernooy, Angelo Auricchio
BACKGROUND: Validation of voltage-based scar delineation has been limited to small populations using mainly endocardial measurements. The aim of this study is to compare unipolar voltage amplitudes (UnipV) with scar on delayed enhancement cardiac magnetic resonance imaging (DE-CMR). METHODS: Heart failure patients who underwent DE-CMR and electro-anatomic mapping were included. Thirty-three endocardial mapped patients and 27 epicardial mapped patients were investigated...
2017: PloS One
https://www.readbyqxmd.com/read/28675582/optimization-of-dual-energy-ct-acquisitions-for-proton-therapy-using-projection-based-decomposition
#14
Gloria Vilches-Freixas, Jean Michel Létang, Nicolas Ducros, Simon Rit
PURPOSE: Dual-energy computed tomography (DECT) has been presented as a valid alternative to single-energy CT to reduce the uncertainty of the conversion of patient CT numbers to proton stopping power ratio (SPR) of tissues relative to water. The aim of this work was to optimize DECT acquisition protocols from simulations of X-ray images for the treatment planning of proton therapy using a projection-based dual-energy decomposition algorithm. METHODS: We have investigated the effect of various voltages and tin filtration combinations on the SPR map accuracy and precision, and the influence of the dose allocation between the low energy (LE) and the high energy (HE) acquisitions...
July 4, 2017: Medical Physics
https://www.readbyqxmd.com/read/28670858/rotors-exhibit-greater-surface-ecg-variation-during-ventricular-fibrillation-than-focal-sources-due-to-wavebreak-secondary-rotors-and-meander
#15
Gordon Ho, Christopher T Villongco, Omid Yousefian, Aaron Bradshaw, Andrew Nguyen, Yonatan Faiwiszewski, Justin Hayase, Wouter-Jan Rappel, Andrew D McCulloch, David E Krummen
INTRODUCTION: Ventricular fibrillation is a common life-threatening arrhythmia. The ECG of VF appears chaotic but may allow identification of sustaining mechanisms to guide therapy. HYPOTHESIS: We hypothesized that rotors and focal sources manifest distinct features on the ECG, and computational modeling may identify mechanisms of such features. METHODS: VF induction was attempted in 31 patients referred for ventricular arrhythmia ablation...
July 3, 2017: Journal of Cardiovascular Electrophysiology
https://www.readbyqxmd.com/read/28670151/dual-energy-ct-new-horizon-in-medical-imaging
#16
REVIEW
Hyun Woo Goo, Jin Mo Goo
Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations. Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT. To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail. Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning...
July 2017: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
https://www.readbyqxmd.com/read/28667054/analysis-of-decreases-in-systemic-arterial-pressure-and-heart-rate-in-response-to-the-hydrogen-sulfide-donor-sodium-sulfide
#17
Kevin W Swan, Bryant Minkyu Song, Allen L Chen, Travis J Chen, Ryan A Chan, Bradley T Guidry, Prasad V G Katakam, Edmund K Kerut, Thomas D Giles, Philip Kadowitz
The actions of hydrogen sulfide (H2S) on the heart and vasculature have been extensively reported. However, the mechanisms underlying the effects of H2S are unclear in the anesthetized rat. The objective of the current study is to investigate the effect of H2S on the electrocardiogram and examine the relationship between H2S-induced changes in heart rate (HR), mean arterial pressure (MAP), and respiratory function. Intravenous (iv) administration of the H2S donor sodium sulfide (Na2S) in the anesthetized Sprague-Dawley (SD) rat decreased MAP and HR and produced changes in respiratory function...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28664343/catheter-ablation-of-atypical-atrial-flutter-a-novel-3d-anatomic-mapping-approach-to-quickly-localize-and-terminate-atypical-atrial-flutter
#18
Sri Sundaram, William Choe, J Ryan Jordan, Nate Mullins, Charles Boorman, Eric J Kessler, Sunil Nath
PURPOSE: This study aims to describe a novel method of High Density Activation Sequence Mapping combined with Voltage Gradient Mapping Overlay (HD-VGM) to quickly localize and terminate atypical atrial flutter. METHODS: Twenty-one patients presenting with 26 different atypical atrial flutter circuits after a previous catheter or surgical AF ablation were studied. HD-VGM was performed with a commercially available impedance-based mapping system to locate and successfully ablate the critical isthmus of each tachycardia circuit...
June 29, 2017: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
https://www.readbyqxmd.com/read/28663199/behavioral-consequences-of-a-bifacial-map-in-the-mouse-somatosensory-cortex
#19
Vassiliy Tsytsarev, Hiroyuki Arakawa, Shuxin Zhao, Alain Chédotal, Reha S Erzurumlu
The whisker system is an important sensory organ with extensive neural representations in the brain of the mouse. Patterned neural modules (barrelettes) in the ipsilateral principal sensory nucleus of the trigeminal nerve (PrV) correspond to the whiskers. Axons of the PrV barrelette neurons cross the midline, and confer the whisker-related patterning to the contralateral ventroposteromedial (VPM) nucleus of the thalamus, and subsequently to the cortex. In this way, specific neural modules called barreloids and barrels in the contralateral thalamus and cortex represent each whisker...
June 29, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28652171/common-and-diverse-elements-of-ion-channels-and-receptors-underlying-electrical-activity-in-endocrine-pituitary-cells
#20
REVIEW
Patrick A Fletcher, Arthur Sherman, Stanko S Stojilkovic
The pituitary gland contains six types of endocrine cells defined by hormones they secrete: corticotrophs, melanotrophs, gonadotrophs, thyrotrophs, somatotrophs, and lactotrophs. All these cell types are electrically excitable, and voltage-gated calcium influx is the major trigger for their hormone secretion. Along with hormone intracellular content, G-protein-coupled receptor and ion channel expression can also be considered as defining cell type identity. While many aspects of the developmental and activity dependent regulation of hormone and G-protein-coupled receptor expression have been elucidated, much less is known about the regulation of the ion channels needed for excitation-secretion coupling in these cells...
June 23, 2017: Molecular and Cellular Endocrinology
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