keyword
MENU ▼
Read by QxMD icon Read
search

Direct flow valve

keyword
https://www.readbyqxmd.com/read/29303334/spin-transfer-due-to-quantum-magnetization-fluctuations
#1
Andrei Zholud, Ryan Freeman, Rongxing Cao, Ajit Srivastava, Sergei Urazhdin
We utilize a nanoscale magnetic spin-valve structure to demonstrate that current-induced magnetization fluctuations at cryogenic temperatures result predominantly from the quantum fluctuations enhanced by the spin transfer effect. The demonstrated spin transfer due to quantum magnetization fluctuations is distinguished from the previously established current-induced effects by a nonsmooth piecewise-linear dependence of the fluctuation intensity on current. It can be driven not only by the directional flows of spin-polarized electrons, but also by their thermal motion and by scattering of unpolarized electrons...
December 22, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29286428/stenosis-of-the-inferior-vena-cava-a-murine-model-of-deep-vein-thrombosis
#2
Holly Payne, Alexander Brill
Deep vein thrombosis (DVT) and its devastating complication, pulmonary embolism, are a severe health problem with high mortality. Mechanisms of thrombus formation in veins remain obscure. Lack of mobility (e.g., after surgery or long-haul flights) is one of the main factors leading to DVT. The pathophysiological consequence of the lack of mobility is blood flow stagnation in venous valves. Here, a model is described that mimics such flow disturbance as a thrombosis-driving factor. In this model, partial flow restriction (stenosis) in the inferior vena cava (IVC) is created...
December 22, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29243687/sutureless-valves-and-the-quality-of-perfusion-towards-a-goal-directed-aortic-valve-replacement
#3
Antonino S Rubino, Carmelo Mignosa
BACKGROUND: Aim of this study was to assess the potential differences in respecting the principles of goal-directed perfusion between aortic valve replacement with sutureless vs conventional stented bioprostheses. METHODS: Data from 94 consecutive patients undergoing aortic valve replacement with Perceval sutureless valve, with or without concomitant CABG, were compared to a contemporary cohort of 116 patients receiving conventional stented bioprostheses. Propensity score matching was used to reduce selection bias...
December 14, 2017: Minerva Cardioangiologica
https://www.readbyqxmd.com/read/29238765/bacteriorhodopsin-based-non-magnetic-spin-filters-for-biomolecular-spintronics
#4
Vaibhav Varade, Tal Markus, Kiran Vankayala, Noga Friedman, Mordechai Sheves, David H Waldeck, Ron Naaman
We discuss spin injection and spin valves, which are based on organic and biomolecules, that offer the possibility to overcome some of the limitations of solid-state devices, which are based on ferromagnetic metal electrodes. In particular, we discuss spin filtering through bacteriorhodopsin in a solid state biomolecular spin valve that is based on the chirality induced spin selectivity (CISS) effect and shows a magnetoresistance of ∼2% at room temperature. The device is fabricated using a layer of bacteriorhodopsin (treated with n-octyl-thioglucoside detergent: OTG-bR) that is adsorbed on a cysteamine functionalized gold electrode and capped with a magnesium oxide layer as a tunneling barrier, upon which a Ni top electrode film is placed and used as a spin analyzer...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29229150/echocardiography-allows-for-analysis-of-pulmonary-arterial-flow-in-mice-with-congenital-diaphragmatic-hernia
#5
Mansi Shah, Michael R Phillips, Megan Quintana, Gary Stupp, Sean E McLean
BACKGROUND: Congenital diaphragmatic hernia (CDH) is a structural birth defect associated with pulmonary hypoplasia and pulmonary arterial hypertension (PAH). We hypothesize that echocardiography provides a method to assess real-time right ventricle (RV) function, remodeling, and pulmonary artery (PA) flow. MATERIALS AND METHODS: Slit3 wild-type (WT) (n = 6) and knockout (KO) (n = 5) mice were analyzed at 2-3 months of age. Mice were anesthetized using isoflurane...
January 2018: Journal of Surgical Research
https://www.readbyqxmd.com/read/29206322/4d-flow-mri-cardiac-function-and-t1-mapping-association-of-valve-mediated-changes-in-aortic-hemodynamics-with-left-ventricular-remodeling
#6
Julia Geiger, Amir A Rahsepar, Kenichiro Suwa, Alex Powell, Ahmadreza Ghasemiesfe, Alex J Barker, Jeremy D Collins, James C Carr, Michael Markl
BACKGROUND: Patients with bicuspid aortic valve (BAV) show altered hemodynamics in the ascending aorta that can be assessed by 4D flow MRI. PURPOSE: Comprehensive cardiac MRI was applied to test the hypothesis that BAV-mediated changes in aortic hemodynamics (wall shear stress [WSS] and velocity) are associated with parameters of left ventricular (LV) remodeling. STUDY TYPE: Retrospective data analysis. POPULATION: Forty-nine BAV patients (mean age = 50...
December 5, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29183943/anisotropic-shear-stress-patterns-predict-the-orientation-of-convergent-tissue-movements-in-the-embryonic-heart
#7
Francesco Boselli, Emily Steed, Jonathan B Freund, Julien Vermot
Myocardial contractility and blood flow provide essential mechanical cues for the morphogenesis of the heart. In general, endothelial cells change their migratory behavior in response to shear stress patterns, according to flow directionality. Here, we assessed the impact of shear stress patterns and flow directionality on the behavior of endocardial cells, the specialized endothelial cells of the heart. At the early stages of zebrafish heart valve formation, we show that endocardial cells are converging to the valve-forming area and that this behavior depends upon mechanical forces...
December 1, 2017: Development
https://www.readbyqxmd.com/read/29098290/fluid-structure-interaction-models-of-bicuspid-aortic-valves-the-effects-of-non-fused-cusp-angles
#8
Karin Lavon, Rotem Halevi, Gil Marom, Sagit Ben Zekry, Ashraf Hamdan, Hans Joachim Schäfers, Ehud Raanani, Rami Haj-Ali
Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5-2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the non-fused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance...
November 2, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29096125/biaxial-mechanical-behavior-of-bovine-saphenous-venous-valve-leaflets
#9
Jiaqi Lu, Hsiao-Ying Shadow Huang
Chronic venous disease is caused by chronic venous insufficiency (CVI), which results in significant symptoms such as venous ulcers, ankle eczema, leg swelling, etc. Venous valve incompetence is a major cause of CVI. When the valves of veins in the leg become incompetent (i.e., do not close properly), blood is able to flow backwards (i.e., reflux), which results in blood pooling in the lower extremities, distal venous hypertension, and CVI. Current clinical therapies, such as surgical venous valve reconstruction and bioprosthetic venous valve replacement, are highly invasive and only moderately successful...
October 24, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/29049564/a-new-technique-to-implant-a-transcatheter-inflatable-fully-repositionable-prosthesis-in-aortic-stenosis-with-severe-asymmetric-calcification
#10
Hasan Bushnaq, Christoph Raspé, Alper Öner, Seyrani Yücel, Hüseyin Ince, Sebastian-Patrick Sommer
OBJECTIVES: In contrast to stented transcatheter aortic valves, the Direct Flow Medical (DFM) valve is a stentless bovine aortic bioprosthesis mounted in a non-metallic inflatable frame. Hence, severe asymmetric annular calcification may result in residually elevated transaortic pressure gradients after DFM implantation. We present a novel intraprocedural dilatation (IDIL) technique for successful implantation of the DFM valve in the presence of complex annular calcification. METHODS: Between January 2014 and May 2015, 55 patients underwent DFM valve-based transcatheter aortic valve implantation at our institution...
November 1, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/29045279/leaflet-kinematics-of-mechanical-and-bioprosthetic-aortic-valve-prostheses
#11
Bernhard Vennemann, Thomas Rösgen, Paul Philipp Heinisch, Dominik Obrist
The hemodynamic performance of artificial aortic valves (AVs) and the probability for structural valve deterioration can be linked to the valve kinematics. Comparability among different studies is limited because of variations in the experimental setups and physiologic boundary conditions. This study presents results of kinematic measurements of bioprosthetic and mechanical AVs that were tested in an identical experimental setting such that they can be directly compared with each other. The kinematics of AVs is typically presented in the form of the geometric orifice area and its temporal evolution...
October 18, 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/29042413/mitral-leaflet-changes-following-myocardial-infarction-clinical-evidence-for-maladaptive-valvular-remodeling
#12
Jonathan Beaudoin, Jacob P Dal-Bianco, Elena Aikawa, Joyce Bischoff, J Luis Guerrero, Suzanne Sullivan, Philipp Emanuel Bartko, Mark D Handschumacher, Dae-Hee Kim, Jill Wylie-Sears, Jacob Aaron, Robert A Levine
BACKGROUND: Ischemic mitral regurgitation (MR) is classically ascribed to functional restriction of normal leaflets, but recent studies have suggested post-myocardial infarction (MI) mitral valve (MV) leaflet fibrosis and thickening, challenging valve normality. Progression of leaflet thickness post-MI has not been studied. We hypothesized that excessive MV remodeling post-MI contributes to MR. Our objectives are to characterize MV changes after MI and relate them to MR. METHODS AND RESULTS: Three groups of 40 patients with serial echocardiograms over a mean of 23...
November 2017: Circulation. Cardiovascular Imaging
https://www.readbyqxmd.com/read/29023351/rapid-deployment-aortic-valves-deliver-superior-hemodynamic-performance-in-vitro
#13
Lisong Ai, Harvey Chen, Virginia Lin, Vinayak N Bapat
OBJECTIVE: Clinical studies have demonstrated excellent hemodynamic performance of rapid deployment aortic valves; however, few studies have directly compared the performance of these valves with conventional bioprosthetic valves. Thus, the hemodynamic function of the EDWARDS INTUITY valve (rapid deployment valve) was compared with the Edwards Magna Ease valve in vitro (Edwards Lifesciences Corp, Irvine, CA USA). METHODS: Elastomeric material was used to create an aortic root model that included a left ventricular outflow tract and aortic annulus...
September 2017: Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery
https://www.readbyqxmd.com/read/28983742/multi-resolution-geometric-modeling-of-the-mitral-heart-valve-leaflets
#14
Amir H Khalighi, Andrew Drach, Robert C Gorman, Joseph H Gorman, Michael S Sacks
An essential element of cardiac function, the mitral valve (MV) ensures proper directional blood flow between the left heart chambers. Over the past two decades, computational simulations have made marked advancements toward providing powerful predictive tools to better understand valvular function and improve treatments for MV disease. However, challenges remain in the development of robust means for the quantification and representation of MV leaflet geometry. In this study, we present a novel modeling pipeline to quantitatively characterize and represent MV leaflet surface geometry...
October 5, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28976942/reconfigurable-microfluidic-magnetic-valve-arrays-towards-a-radiotherapy-compatible-spheroid-culture-platform-for-the-combinatorial-screening-of-cancer-therapies
#15
Alexandre R Brunet, Frédérique Labelle, Philip Wong, Thomas Gervais
We introduce here a microfluidic cell culture platform or spheroid culture chamber array (SCCA) that can synthesize, culture, and enable fluorescence imaging of 3D cell aggregates (typically spheroids) directly on-chip while specifying the flow of reagents in each chamber via the use of an array of passive magnetic valves. The SCCA valves demonstrated sufficient resistance to burst (above 100 mBar), including after receiving radiotherapy (RT) doses of up to 8 Gy combined with standard 37 °C incubation for up to 7 days, enabling the simultaneous synthesis of multiple spheroids from different cell lines on the same array...
October 4, 2017: Sensors
https://www.readbyqxmd.com/read/28948696/benign-prostatic-hyperplasia-long-term-follow-up-of-prostate-volume-reduction-after-sclerotherapy-of-the-internal-spermatic-veins
#16
Y Gat, M Goren
The purpose was to examine the results of bilateral percutaneous sclerotherapy of the internal spermatic veins on prostate volume and prostatic symptoms. We previously showed that destruction of one-way valves in the internal spermatic veins (varicocele) elevates hydrostatic pressure in the vertical testicular venous drainage system in the erect human. This diverts free testosterone (FT) flow at high concentrations directly from the testes into the prostate. High intraprostatic FT prolongs prostate cell life and increases cell proliferation rate-synergistic effects resulting in increased cell population (BPH)...
September 25, 2017: Andrologia
https://www.readbyqxmd.com/read/28941127/a-comparison-of-the-fully-repositionable-and-retrievable-boston-lotus-and-direct-flow-medical-valves-for-the-treatment-of-severe-aortic-stenosis-a-single-center-experience
#17
Francesco Giannini, Azeem Latib, Matteo Montorfano, Neil Ruparelia, Vittorio Romano, Matteo Longoni, Luca Ferri, Richard Jabbour, Antonio Mangieri, Damiano Regazzoli, Marco Ancona, Nicola Buzzatti, Lorenzo Azzalini, Akihito Tanaka, Eustachio Agricola, Alaide Chieffo, Ottavio Alfieri, Antonio Colombo
BACKGROUND: Second generation transcatheter aortic valve implantation (TAVI) devices have been designed to reduce the rate of paravalvular leak (PVL) and other complications. An important technological advancement has been the ability to fully reposition devices to facilitate optimal implantation depth and position to reduce the likelihood of PVL. OBJECTIVES: To compare procedural and 30-day outcomes according to the Valve Academic Research Consortium (VARC)-2 criteria following TAVI with the fully repositionable and retrievable Lotus and DFM devices...
September 20, 2017: Catheterization and Cardiovascular Interventions
https://www.readbyqxmd.com/read/28921052/in-vitro-evaluation-of-flow-patterns-and-turbulent-kinetic-energy-in-trans-catheter-aortic-valve-prostheses
#18
Daniel Giese, Kilian Weiss, Bettina Baeßler, Navid Madershahian, Yeong-Hoon Choi, David Maintz, Alexander C Bunck
OBJECTIVES: The objective of the current work was to evaluate flow and turbulent kinetic energy in different transcatheter aortic valve implants using highly undersampled time-resolved multi-point 3-directional phase-contrast measurements (4D Flow MRI) in an in vitro setup. MATERIALS AND METHODS: A pulsatile flow setup was used with a compliant tubing mimicking a stiff left ventricular outflow tract and ascending aorta. Five different implants were measured using a highly undersampled multi-point 4D Flow MRI sequence...
September 18, 2017: Magma
https://www.readbyqxmd.com/read/28917773/redesigning-flow-injection-after-40-years-of-development-flow-programming
#19
Jaromir Jarda Ruzicka
Automation of reagent based assays, by means of Flow Injection (FI), is based on sample processing, in which a sample flows continuously towards and through a detector for quantification of the target analyte. The Achilles heel of this methodology, the legacy of Auto Analyzer®, is continuous reagent consumption, and continuous generation of chemical waste. However, flow programming, assisted by recent advances in precise pumping, combined with the lab-on-valve technique, allows the FI manifold to be designed around a single confluence point through which sample and reagents are sequentially directed by means of a series of flow reversals...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28900614/echocardiographic-evaluation-of-pulmonary-pressures-and-right-ventricular-function-after-pediatric-cardiac-surgery-a-simple-approach-for-the-intensivist
#20
REVIEW
Maurice Beghetti
Pulmonary hypertension (PH) is diagnosed using cardiac catheterization and is defined as an elevation of mean pulmonary artery pressure (PAP) greater than 25 mmHg. Although invasive hemodynamics remains the gold standard and is mandatory for disease confirmation, transthoracic echocardiography (TTE) is an extremely useful non-invasive and widely available tool that allows for screening and follow-up, in particular, in the acute setting. TTE may be a valuable alternative, allowing for direct measurement and/or indirect assessment of PAP...
2017: Frontiers in Pediatrics
keyword
keyword
44532
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"