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https://www.readbyqxmd.com/read/28517046/three-dimensional-proximal-flow-convergence-automatic-calculation-for-determining-mitral-valve-area-in-rheumatic-mitral-stenosis
#1
Francisco Sampaio, Ricardo Ladeiras-Lopes, João Almeida, Paulo Fonseca, Ricardo Fontes-Carvalho, José Ribeiro, Vasco Gama
PURPOSE: Management of patients with mitral stenosis (MS) depends heavily on the accurate quantification of mitral valve area (MVA) using echocardiography. All currently used two-dimensional (2D) methods have limitations. Estimation of MVA using the proximal isovelocity surface area (PISA) method with real time three-dimensional (3D) echocardiography may circumvent those limitations. We aimed to evaluate the accuracy of 3D direct measurement of PISA in the estimation of MVA. METHODS: Twenty-seven consecutive patients (median age of 63 years; 77...
May 18, 2017: Echocardiography
https://www.readbyqxmd.com/read/28465035/high-pressure-liquid-chromatography-with-direct-injection-of-gas-sample
#2
Anton I Astanin, Grigory I Baram
The conventional method of using liquid chromatography to determine the composition of a gaseous mixture entails dissolving vapors in a suitable solvent, then obtaining a chromatograph of the resulting solution. We studied the direct introduction of a gaseous sample into a C18 reversed-phase column, followed by separation of the components by HPLC with UV detection. Since the chromatography was performed at high pressure, vapors readily dissolved in the eluent and the substances separated in the column as effectively as in liquid samples...
April 23, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28460569/neurological-outcome-and-frequency-of-overdrainage-in-normal-pressure-hydrocephalus-directly-correlates-with-implanted-ventriculo-peritoneal-shunt-valve-type
#3
Yavor Bozhkov, Karl Roessler, Nirjhar Hore, Michael Buchfelder, Sebastian Brandner
BACKGROUND: The correlation between neurological outcome and frequency of overdrainage in the management of idiopathic normal pressure hydrocephalus (iNPH) using different ventriculoperitoneal shunt valve types is under investigation. Thus, we retrospectively compared one group of iNPH patients implanted with a programmable differential pressure valve (DPV) with another group treated by implantation of a DPV in combination with a flow-regulated anti-siphon device valve (ASD). METHODS: A retrospective evaluation of clinical outcome and frequency of overdrainage of 40 consecutive iNPH patients following surgical management between 08/2010 and 08/2014 was performed...
May 1, 2017: Neurological Research
https://www.readbyqxmd.com/read/28450039/characterization-of-chronic-aortic-and-mitral-regurgitation-undergoing-valve-surgery-using-cardiovascular-magnetic-resonance
#4
Christian L Polte, Sinsia A Gao, Åse A Johnsson, Kerstin M Lagerstrand, Odd Bech-Hanssen
Grading of chronic aortic regurgitation (AR) and mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR) is currently based on thresholds, which are neither modality nor quantification method specific. Accordingly, this study sought to identify CMR-specific and quantification method-specific thresholds for regurgitant volumes (RVols), RVol indexes, and regurgitant fractions (RFs), which denote severe chronic AR or MR with an indication for surgery. The study comprised patients with moderate and severe chronic AR (n = 38) and MR (n = 40)...
March 29, 2017: American Journal of Cardiology
https://www.readbyqxmd.com/read/28427597/intentional-percutaneous-laceration-of%C3%A2-the%C3%A2-anterior-mitral-leaflet-to-prevent%C3%A2-outflow%C3%A2-obstruction-during-transcatheter-mitral-valve-replacement-first-in-human%C3%A2-experience
#5
Vasilis C Babaliaros, Adam B Greenbaum, Jaffar M Khan, Toby Rogers, Dee Dee Wang, Marvin H Eng, William W O'Neill, Gaetano Paone, Vinod H Thourani, Stamatios Lerakis, Dennis W Kim, Marcus Y Chen, Robert J Lederman
OBJECTIVES: This study sought to use a new catheter technique to split the anterior mitral valve leaflet (AML) and prevent iatrogenic left ventricular outflow tract (LVOT) obstruction immediately before transcatheter mitral valve replacement (TMVR). BACKGROUND: LVOT obstruction is a life-threatening complication of TMVR, caused by septal displacement of the AML. METHODS: The procedure was used in patients with severe mitral valve disease and prohibitive surgical risk...
April 24, 2017: JACC. Cardiovascular Interventions
https://www.readbyqxmd.com/read/28424229/tension-activated-channels-in-the-mechanism-of-osmotic-fitness-in-pseudomonas-aeruginosa
#6
Uğur Çetiner, Ian Rowe, Anthony Schams, Christina Mayhew, Deanna Rubin, Andriy Anishkin, Sergei Sukharev
Pseudomonas aeruginosa (PA) is an opportunistic pathogen with an exceptional ability to adapt to a range of environments. Part of its adaptive potential is the ability to survive drastic osmolarity changes. Upon a sudden dilution of external medium, such as during exposure to rain, bacteria evade mechanical rupture by engaging tension-activated channels that act as osmolyte release valves. In this study, we compare fast osmotic permeability responses in suspensions of wild-type PA and Escherichia coli (EC) strains in stopped-flow experiments and provide electrophysiological descriptions of osmotic-release channels in PA...
May 1, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28391858/dual-thermostating-in-flow-analysis
#7
Tuanne R Dias, Milton K Sasaki, Elias A G Zagatto
An advanced strategy involving concentric tubes is proposed for fast and controlled heating (or cooling) of the reaction medium in flow analysis. Different temperatures are set by sequentially circulating two thermostated water streams through the outer larged bore (2.0mm i.d.) silicone tube, which acted as a water-jacket of the inner (0.8mm i.d.) PTFE tube, and directing the sample zone to flow through it. Each end of the outer tube is connected to a three-way valve that selects the stream to flow inside it...
June 1, 2017: Talanta
https://www.readbyqxmd.com/read/28389690/energy-dynamics-of-the-intraventricular-vortex-after-mitral-valve-surgery
#8
Kouki Nakashima, Keiichi Itatani, Tadashi Kitamura, Norihiko Oka, Tetsuya Horai, Shohei Miyazaki, Masaki Nie, Kagami Miyaji
Mitral valve morphology after mitral valve surgery affects postoperative intraventricular flow patterns and long-term cardiac performance. We visualized ventricular flow by echocardiography vector flow mapping (VFM) to reveal the impact of different mitral valve procedures. Eleven cases of mechanical mitral valve replacement (nine in the anti-anatomical and two in the anatomical position), three bioprosthetic mitral valve replacements, and four mitral valve repairs were evaluated. The mean age at the procedure was 57...
April 7, 2017: Heart and Vessels
https://www.readbyqxmd.com/read/28372840/restriction-capillaries-as-an-innovative-mixing-unit-for-intermediate-mobile-phase-exchange-in-multidimensional-analysis
#9
Glenn Loos, Konstantin Shoykhet, Monika Dittmann, Deirdre Cabooter
A novel mixing unit is proposed for the serial coupling of orthogonal columns to analyze polar and non-polar compounds in a single run. The principle relies on the isolation of unretained peaks eluting from a first dimension column in a sample loop, before directing them to a second column for separation. Since the mobile phases employed in highly orthogonal separations are not directly compatible, a mixing unit is required to alter the mobile phase composition before executing the second dimension separation...
May 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28359612/evaluation-of-one-way-valves-used-in-medical-devices-for-prevention-of-cross-contamination
#10
Poulomi Nandy, Megan Young, Shanil P Haugen, Kristy Katzenmeyer-Pleuss, Edward A Gordon, Stephen M Retta, Steven C Wood, Anne D Lucas
BACKGROUND: One-way valves used in day use devices (used on multiple patients throughout a day without reprocessing between patients) are intended to reduce the potential for cross-contamination between patients resulting from the backflow of patient fluids. One-way valves are typically designed to withstand high levels of back pressure before failure; however, they may not be explicitly designed as a means of infection control as used in medical device applications. METHODS: Five different medical grade one-way valves were placed in low pressure configurations...
March 27, 2017: American Journal of Infection Control
https://www.readbyqxmd.com/read/28355935/proof-of-concept-evaluation-of-the-sailvalve-self-expanding-deep-venous-valve-system-in-a-porcine-model
#11
Doeke Boersma, Aryan Vink, Frans L Moll, Gert J de Borst
PURPOSE: To evaluate the SailValve, a new self-expanding deep venous valve concept based on a single polytetrafluoroethylene cusp floating up and down in the bloodstream like a sail, acting as a flow regulator and allowing minimal reflux to reduce thrombogenicity. METHODS: Both iliac veins of 5 pigs were implanted with SailValve devices; the first animal was an acute pilot experiment to show the feasibility of accurately positioning the SailValve via a femoral access...
March 1, 2017: Journal of Endovascular Therapy
https://www.readbyqxmd.com/read/28350018/frequency-tuning-allows-flow-direction-control-in-microfluidic-networks-with-passive-features
#12
Rahil Jain, Barry Lutz
Frequency tuning has emerged as an attractive alternative to conventional pumping techniques in microfluidics. Oscillating (AC) flow driven through a passive valve can be rectified to create steady (DC) flow, and tuning the excitation frequency to the characteristic (resonance) frequency of the underlying microfluidic network allows control of flow magnitude using simple hardware, such as an on-chip piezo buzzer. In this paper, we report that frequency tuning can also be used to control the direction (forward or backward) of the rectified DC flow in a single device...
May 2, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28321684/left-ventricular-flow-propagation-velocity-measurement-is-it-cast-in-stone
#13
Bee Ting Chan, Hak Koon Yeoh, Yih Miin Liew, Yang Faridah Abdul Aziz, Ganiga Srinivasaiah Sridhar, Christian Hamilton-Craig, David Platts, Einly Lim
This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle...
March 20, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28317480/novel-insights-into-complex-cardiovascular-pathologies-using-4d-flow-analysis-by-cardiovascular-magnetic-resonance-imaging
#14
Adam James Lewandowski, Betty Raman, Rajarshi Banerjee, Matteo Milanesi
BACKGROUND: It is essential that we are able to assess variations in blood flow in order to fully understand cardiovascular function in disease pathologies and for identification of individuals at long-term risk of cardiovascular disease development. Qualitative and quantitative assessments of blood flow by imaging modalities have been limited, and much of the accurate quantification has relied on invasive measures. METHODS: This review discusses how four-dimensional velocity cardiovascular magnetic resonance (4D flow CMR) offers increasing potential for the non-invasive assessment of blood flow in the heart and major blood vessels such as the aorta...
March 17, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28299822/when-to-use-femoral-vein-injection-for-diagnosis-of-patent-foramen-ovale-effect-of-a-persistent-eustachian-valve-on-right-atrial-flow-patterns-during-contrast-transesophageal-echocardiography
#15
Tat W Koh
Contrast echocardiography using agitated saline injected into the antecubital vein is the most common method used for the diagnosis of patent foramen ovale. We describe a case whereby the presence of a persistent eustachian valve and a "negative contrast sign" during contrast transesophageal echocardiography raised suspicion of a false-negative result. Femoral vein injection of contrast successfully demonstrated a patent foramen ovale. Femoral vein injection should be considered if this scenario is recognized because the eustachian valve directs blood preferentially from the inferior vena cava toward the interatrial septum and this route may prove to be more reliable...
March 16, 2017: Echocardiography
https://www.readbyqxmd.com/read/28292302/impact-of-left-ventricular-outflow-tract-ellipticity-on-the-grading-of-aortic-stenosis-in-patients-with-normal-ejection-fraction
#16
Frédéric Maes, Sophie Pierard, Christophe de Meester, Jamila Boulif, Mihaela Amzulescu, David Vancraeynest, Anne-Catherine Pouleur, Agnès Pasquet, Bernhard Gerber, Jean-Louis Vanoverschelde
BACKGROUND: The pathophysiology of paradoxical low-gradient (LG) severe aortic stenosis (SAS) remains controversial. As low transvalvular flow has been implicated, we sought to investigate the impact of left ventricular outflow tract (LVOT) ellipticity on the estimation of the LV stroke volume, the calculation of the aortic valve area (AVA) by use of the continuity equation and on AS severity grading. METHODS: We studied 190 consecutive patients (mean age: 72 ± 13 years; male: 57%) with SAS (indexed AVA < 0...
March 15, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28285747/effect-of-the-ventricular-folds-in-a-synthetic-larynx-model
#17
Stefan Kniesburges, Veronika Birk, Alexander Lodermeyer, Anne Schützenberger, Christopher Bohr, Stefan Becker
Within the human larynx, the ventricular folds serve primarily as a protecting valve during swallowing. They are located directly above the sound-generating vocal folds. During normal phonation, the ventricular folds are passive structures that are not excited to periodical oscillations. However, the impact of the ventricular folds on the phonation process has not yet been finally clarified. An experimental synthetic human larynx model was used to investigate the effect of the ventricular folds on the phonation process...
April 11, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28270219/quantification-of-aortic-stenosis-diagnostic-parameters-comparison-of-fast-3-direction-and-1-direction-phase-contrast-cmr-and-transthoracic-echocardiography
#18
Juliana Serafim da Silveira, Matthew Smyke, Adam V Rich, Yingmin Liu, Ning Jin, Debbie Scandling, Jennifer A Dickerson, Carlos E Rochitte, Subha V Raman, Lee C Potter, Rizwan Ahmad, Orlando P Simonetti
BACKGROUND: Aortic stenosis (AS) is a common valvular disorder, and disease severity is currently assessed by transthoracic echocardiography (TTE). However, TTE results can be inconsistent in some patients, thus other diagnostic modalities such as cardiovascular magnetic resonance (CMR) are demanded. While traditional unidirectional phase-contrast CMR (1Dir PC-CMR) underestimates velocity if the imaging plane is misaligned to the flow direction, multi-directional acquisitions are expected to improve velocity measurement accuracy...
March 7, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28254880/formation-and-function-of-intracardiac-valve-cells-in-the-drosophila-heart
#19
Kay Lammers, Bettina Abeln, Mirko Hüsken, Christine Lehmacher, Olympia Ekaterini Psathaki, Esther Alcorta, Heiko Meyer, Achim Paululat
Drosophila harbors a simple tubular heart that ensures hemolymph circulation within the body. The heart is built by a few different cell types, including cardiomyocytes that define the luminal heart channel and ostia cells that constitute openings in the heart wall allowing hemolymph to enter the heart chamber. Regulation of flow directionality within a tube, such as blood flow in arteries or insect hemolymph within the heart lumen, requires a dedicated gate, valve, or flap-like structure that prevents backflow of fluids...
March 2, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28230344/fully-automatic-in-syringe-magnetic-stirring-assisted-dispersive-liquid-liquid-microextraction-hyphenated-to-high-temperature-torch-integrated-sample-introduction-system-inductively-coupled-plasma-spectrometer-with-direct-injection-of-the-organic-phase
#20
Raquel Sánchez, Burkhard Horstkotte, Kateřina Fikarová, Hana Sklenářová, Salvador Maestre, Manuel Miró, Jose-Luis Todolí
A proof of concept study involving the online coupling of automatic dispersive liquid-liquid microextraction (DLLME) to inductively coupled plasma optical emission spectrometry (ICP OES) with direct introduction and analysis of the organic extract is herein reported for the first time. The flow-based analyzer features a lab-in-syringe (LIS) setup with an integrated stirring system, a Meinhard nebulizer in combination with a heated single-pass spray chamber, and a rotary injection valve, used as an online interface between the microextraction system and the detection instrument...
March 10, 2017: Analytical Chemistry
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