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https://www.readbyqxmd.com/read/28708210/particle-image-velocimetry-tests-on-pediatric-45-cc-and-30-cc-ventricle-assist-devices-effects-of-heart-rate-on-vad-operation
#1
Dariusz Witkowski, Damian Obidowski, Piotr Reorowicz, Daniel Jodko, Krzysztof Jozwik
BACKGROUND: This study investigated flow analysis inside pediatric ventricle assist devices (VADs) designed and manufactured at the Foundation for Cardiac Surgery Development (FRK), Zabrze, Poland. The main goal of the experiment was to define the minimal heart rate admissible in clinical practice. METHODS: The flow was directed by mechanical, single-disc valves developed at the Lodz University of Technology, Institute of Turbomachinery in Lodz, Poland. VAD operation conditions under different heart rates were analyzed...
July 8, 2017: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/28694784/4d-flow-analysis-of-bav-related-fluid-dynamic-alterations-evidences-of-wall-shear-stress-alterations-in-absence-of-clinically-relevant-aortic-anatomical-remodeling
#2
Filippo Piatti, Francesco Sturla, Malenka M Bissell, Selene Pirola, Massimo Lombardi, Igor Nesteruk, Alessandro Della Corte, Alberto C L Redaelli, Emiliano Votta
Bicuspid aortic valve (BAV) is the most common congenital cardiac disease and is a foremost risk factor for aortopathies. Despite the genetic basis of BAV and of the associated aortopathies, BAV-related alterations in aortic fluid-dynamics, and particularly in wall shear stresses (WSSs), likely play a role in the progression of aortopathy, and may contribute to its pathogenesis. To test whether WSS may trigger aortopathy, in this study we used 4D Flow sequences of phase-contrast cardiac magnetic resonance imaging (CMR) to quantitatively compare the in vivo fluid dynamics in the thoracic aorta of two groups of subjects: (i) five prospectively enrolled young patients with normo-functional BAV and with no aortic dilation and (ii) ten age-matched healthy volunteers...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28681601/autonomous-control-of-fluids-in-wide-surface-tension-range-in-microfluidics
#3
Peng Ge, Shuli Wang, Yongshun Liu, Wendong Liu, Nianzuo Yu, Jianglei Zhang, Huaizhong Shen, Junhu Zhang, Bai Yang
In this paper, we report the preparation of anisotropic wetting surfaces that could control various liquids' wetting behavior in wide surface tension range (from water to oil), which could be employed as a platform for flowing control of liquids in microfluidics (MFs). The anisotropic wetting surfaces are chemistry-asymmetric "Janus" silicon cylinder arrays (Si-CAs) which are fabricated via selecting and regulating the functional groups on the surface of each cylinder unit. Liquids (in wide surface tension range) wet in a unidirectional manner along the direction which was modified by group with large surface energy...
July 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28658639/experimental-evaluation-and-analysis-of-methane-fire-and-explosion-mitigation-using-isolation-valves-integrated-with-a-vent-system
#4
Mohammed J Ajrash, Jafar Zanganeh, Behdad Moghtaderi
There has been a surge of interest from the extractive industries in the application of mechanical means to the mitigation of flame deflagration. To verify the implementation and performance of passive and active mitigation protection, a comprehensive experimental investigation has been conducted on a large scale detonation tube, 30m long and 0.5m in diameter, with two mitigation valves (passive and active) and a burst panel venting system. The valves were used alternately to mitigate the flame deflagration of methane in concentrations ranging from 1...
June 20, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28643891/direct-comparison-of-high-temporal-resolution-cine-mri-with-doppler-ultrasound-for-assessment-of-diastolic-dysfunction-in-mice
#5
Thomas A Roberts, Anthony N Price, Laurence H Jackson, Valerie Taylor, Anna L David, Mark F Lythgoe, Daniel J Stuckey
Diastolic dysfunction is a sensitive early indicator of heart failure and can provide additional data to conventional measures of systolic function. Transmitral Doppler ultrasound, which measures the one-dimensional flow of blood through the mitral valve, is currently the preferred method for the measurement of diastolic function, but the measurement of the left ventricular volume changes using high-temporal-resolution cinematic magnetic resonance imaging (CINE MRI) is an alternative approach which is emerging as a potentially more robust and user-independent technique...
June 23, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28620766/phenotype-transformation-of-aortic-valve-interstitial-cells-due-to-applied-shear-stresses-within-a-microfluidic-chip
#6
Xinmei Wang, Joohyung Lee, Mir Ali, Jungkyu Kim, Carla M R Lacerda
Despite valvular heart diseases constituting a significant medical problem, the acquisition of information describing their pathophysiology remains difficult. Due to valvular size, role and location within the body, there is a need for in vitro systems that can recapitulate disease onset and progression. This study combines the development of an in vitro model and its application in the mechanical stimulation of valvular cell transformation. Specifically, porcine aortic valvular interstitial cells (PAVIC) were cultured on polydimethylsiloxane microfluidic devices with or without exposure to shear stresses...
June 15, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28599851/experimental-evaluation-of-control-performance-of-mpc-as-a-regulatory-controller
#7
Mohammad Khan, Malik Tahiyat, Syed Imtiaz, M A A Shoukat Choudhury, Faisal Khan
Proportional-integral-derivative (PID) control is widely practised as the base layer controller in the industry due to its robustness and design simplicity. However, a supervisory control layer over the base layer, namely a model predictive controller (MPC), is becoming increasingly popular with the advent of computer process control. The use of a supervisory layer has led to different control structures. In this study, we perform an objective investigation of several commonly used control structures such as 'Cascaded PI controller', 'DMC cascaded to PI' and 'Direct DMC'...
June 6, 2017: ISA Transactions
https://www.readbyqxmd.com/read/28593469/a-patient-specific-aortic-valve-model-based-on-moving-resistive-immersed-implicit-surfaces
#8
Marco Fedele, Elena Faggiano, Luca Dedè, Alfio Quarteroni
In this paper, we propose a full computational framework to simulate the hemodynamics in the aorta including the valve. Closed and open valve surfaces, as well as the lumen aorta, are reconstructed directly from medical images using new ad hoc algorithms, allowing a patient-specific simulation. The fluid dynamics problem that accounts from the movement of the valve is solved by a new 3D-0D fluid-structure interaction model in which the valve surface is implicitly represented through level set functions, yielding, in the Navier-Stokes equations, a resistive penalization term enforcing the blood to adhere to the valve leaflets...
June 7, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28540067/utility-of-cardiac-magnetic-resonance-for-evaluation-of-mitral-regurgitation-prior-to-mitral-valve-surgery
#9
REVIEW
Neil K Mehta, Jiwon Kim, Jonathan Y Siden, Sara Rodriguez-Diego, Javid Alakbarli, Antonino Di Franco, Jonathan W Weinsaft
Mitral regurgitation (MR) is a common cause of morbidity worldwide and an accepted indication for interventional therapies which aim to reduce or resolve adverse clinical outcomes associated with MR. Cardiac magnetic resonance (CMR) provides highly accurate means of assessing MR, including a variety of approaches that can measure MR based on quantitative flow. Additionally, CMR is widely accepted as a reference standard for cardiac chamber quantification, enabling reliable detection of subtle changes in cardiac chamber size and function so as to guide decision-making regarding timing of mitral valve directed therapies...
April 2017: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28517046/three-dimensional-proximal-flow-convergence-automatic-calculation-for-determining-mitral-valve-area-in-rheumatic-mitral-stenosis
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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...
July 1, 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
#20
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...
June 2017: Journal of Endovascular Therapy
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