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https://www.readbyqxmd.com/read/27855987/simulations-of-morphotype-dependent-hemodynamics-in-non-dilated-bicuspid-aortic-valve-aortas
#1
Kai Cao, Samantha K Atkins, Andrew McNally, Janet Liu, Philippe Sucosky
Bicuspid aortic valves (BAVs) generate flow abnormalities that may promote aortopathy. While positive helix fraction (PHF) index, flow angle (θ), flow displacement (d) and wall shear stress (WSS) exhibit abnormalities in dilated BAV aortas, it is unclear whether those anomalies stem from the abnormal valve anatomy or the dilated aorta. Therefore, the objective of this study was to quantify the early impact of different BAV morphotypes on aorta hemodynamics prior to dilation. Fluid-structure interaction models were designed to quantify standard peak-systolic flow metrics and temporal WSS characteristics in a realistic non-dilated aorta connected to functional tricuspid aortic valve (TAV) and type-I BAVs...
November 11, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/27836502/transcatheter-aortic-valves-produce-unphysiological-flows-which-may-contribute-to-thromboembolic-events-an-in-vitro-study
#2
Andrea Ducci, Francesco Pirisi, Spyridon Tzamtzis, Gaetano Burriesci
PURPOSE: Transcatheter aortic valve implantation (TAVI) has been associated with large incidence of ischemic events, whose sources are still unclear. In fact, sub-acute complications cannot be directly related to the severity of the calcification in the host tissues, nor with catheter manipulation during the implant. A potential cause could be local flow perturbations introduced by the implantation approach, resulting in thrombo-embolic consequences. In particular, contrary to the surgical approach, TAVI preserves the presence of the native leaflets, which are expanded in the paravalvular space inside the Valsalva sinuses...
November 3, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/27806381/integrin-alpha-9-blockade-suppresses-lymphatic-valve-formation-and-promotes-transplant-survival
#3
Gyeong Jin Kang, Tan Truong, Eric Huang, Valerie Su, Shaokui Ge, Lu Chen
Purpose: The lymphatic pathway mediates transplant rejection. We recently reported that lymphatic vessels develop luminal valves in the cornea during lymphangiogenesis, and these valves express integrin alpha 9 (Itga-9) and play a critical role in directing lymph flow. In this study, we used an allogeneic corneal transplantation model to investigate whether Itga-9 blockade could suppress valvulogenesis after transplantation, and how this effect would influence the outcomes of the transplants...
November 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27800679/plug-volume-modulated-dilution-generator-for-flask-free-chemistry
#4
Pei-Han Liu, Pawel L Urban
Dilution is one of the common chemical procedures, which are carried out in all chemistry laboratories - to prepare standard solutions with different concentrations for assay calibration, and to reduce matrix effects while handling complex samples. Yet dilution is mostly performed manually using large-volume manual liquid-handling tools (volumetric flasks, graduated cylinders, and pipettes). Here we describe a simple continuous and automated method of diluting complex samples and stock solutions using an Arduino-based control unit...
November 1, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/27783858/heart-valve-biomechanics-and-underlying-mechanobiology
#5
Salma Ayoub, Giovanni Ferrari, Robert C Gorman, Joseph H Gorman, Frederick J Schoen, Michael S Sacks
Heart valves control unidirectional blood flow within the heart during the cardiac cycle. They have a remarkable ability to withstand the demanding mechanical environment of the heart, achieving lifetime durability by processes involving the ongoing remodeling of the extracellular matrix. The focus of this review is on heart valve functional physiology, with insights into the link between disease-induced alterations in valve geometry, tissue stress, and the subsequent cell mechanobiological responses and tissue remodeling...
September 15, 2016: Comprehensive Physiology
https://www.readbyqxmd.com/read/27769464/high-temperature-diaphragm-valve-based-comprehensive-two-dimensional-gas-chromatography-with-time-of-flight-mass-spectrometry
#6
Chris E Freye, Robert E Synovec
A high temperature diaphragm valve-based two-dimensional (2D) gas chromatography (GC×GC) with time-of-flight mass spectrometry (TOFMS) instrument, with the valve mounted directly in the GC oven, is demonstrated with separations up to 325°C. Use of the diaphragm valve allowed for the use of uncoupled carrier gas flows for (1)D (first column dimension) and (2)D (second column dimension), with a (1)D flow rate of 1ml/min, and a (2)D flow rate 3ml/min. The 3ml/min flow rate on (2)D was selected to ensure compatibility with most TOFMS detectors...
December 1, 2016: Talanta
https://www.readbyqxmd.com/read/27767047/multi-terminal-spin-valve-on-channels-with-spin-momentum-locking
#7
Shehrin Sayed, Seokmin Hong, Supriyo Datta
It is experimentally established that charge current flowing in a channel with spin-momentum locking such as topological insulator surface states or Rashba interfaces induces a spin voltage, which can be electrically measured with a ferromagnetic contact along the current path. Using this fact in conjunction with Onsager reciprocity arguments, we make the surprising prediction that the anti-parallel resistance of a spin valve can be either larger or smaller than the parallel resistance depending on the direction of spin flow relative to the direction of spin-momentum locking...
October 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27739170/trans-catheter-aortic-valve-implantation-with-the-direct-flow-medical-prosthesis-single-center-short-term-clinical-and-echocardiographic-outcomes
#8
Stephan Kische, Giuseppe D'Ancona, Hüseyin U Agma, Gihan El-Achkar, Martin Dißmann, Jasmin Ortak, Hüseyin Ince
OBJECTIVES: To analyze our single center experience with the Direct Flow Medical (DFM). BACKGROUND: The DFM has been recently introduced to the market and large real world experiences are lacking. METHODS: A total of 126 patients with severe aortic valve stenosis (AVS) were treated by the same team from March 2013 to May 2015. Device success and procedural safety were classified, according to valve academic research consortium (VARC) criteria, for the entire cohort, including patients treated in the early phases of our learning curve...
October 14, 2016: Catheterization and Cardiovascular Interventions
https://www.readbyqxmd.com/read/27739165/transcatheter-aortic-valve-implantation-with-the-direct-flow-medical-prosthesis-impact-of-native-aortic-valve-calcification-degree-on-outcomes
#9
Giuseppe D'Ancona, Hüseyin U Agma, Hüseyin Ince, Gihan El-Achkar, Martin Dißmann, Jasmin Ortak, Stephan Kische
OBJECTIVES: We present our single center experience with the direct flow medical (DFM) prosthesis addressing the impact of native aortic valve (AV) calcification degree on outcomes. BACKGROUND: The DFM® has been introduced for transcatheter aortic valve implantation (TAVI). The valve has a nonmetallic and inflatable support structure. METHODS: Patients were divided in two groups according to preoperative cardiac computed tomography (CT): group I moderate calcification and group II heavy calcification of the total AV area...
October 14, 2016: Catheterization and Cardiovascular Interventions
https://www.readbyqxmd.com/read/27712083/aortic-valve-leaflet-wall-shear-stress-characterization-revisited-impact-of-coronary-flow
#10
K Cao, P Sucosky
Computational characterizations of aortic valve hemodynamics have typically discarded the effects of coronary flow. The objective of this study was to complement our previous fluid-structure interaction aortic valve model with a physiologic coronary circulation model to quantify the impact of coronary flow on aortic sinus hemodynamics and leaflet wall shear stress (WSS). Coronary flow suppressed vortex development in the two coronary sinuses and altered WSS magnitude and directionality on the three leaflets, with the most substantial differences occurring in the belly and tip regions...
October 7, 2016: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/27673368/thermally-induced-triple-shape-hydrogels-soft-materials-enabling-complex-movements
#11
Ulrich Nöchel, Marc Behl, Maria Balk, Andreas Lendlein
Shape-memory hydrogels enable directed movements of a specimen in response to temperature, whereby crystallizable switching segments incorporated as side chains resulted in constant degrees of swelling during the shape-memory cycle. Here we report about hydrogels exhibiting a thermally induced triple-shape effect that allows complex movements of soft materials with two almost independent shape changes. Potential applications for those soft triple-shape materials are two-step self-unfolding devices or temperature-sensitive hydrogel actuators, for example, smart valves for flow rate control in aqueous media...
October 10, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27648730/electrostatic-charge-and-electric-field-induced-smart-gating-for-water-transportation
#12
Kai Xiao, Yahong Zhou, Xiang-Yu Kong, Ganhua Xie, Pei Li, Zhen Zhang, Liping Wen, Lei Jiang
Regulating and controlling the transport of water across nanochannels is of great importance in both fundamental research and practical applications, because it is difficult to externally control water flow through nanochannels as in biological channels. To date, only a few hydrophobic nanochannels controlling the transport of water have been reported, all of which use exotic hydrophobic molecules. However, the effect of electrostatic charges, which plays an indispensable role in membrane proteins and dominates the energetics of water permeation across aquaporins, has not gained enough attention to control water transport through solid-state nanochannel/nanopore...
September 20, 2016: ACS Nano
https://www.readbyqxmd.com/read/27638236/abnormal-ventricular-and-aortic-wall-properties-can-cause-inconsistencies-in-grading-aortic-regurgitation-severity-a-computer-simulation-study
#13
Georgina Palau-Caballero, John Walmsley, John Gorcsan, Joost Lumens, Tammo Delhaas
BACKGROUND: Assessment of aortic regurgitation (AR) severity is often based on Doppler echocardiographic imaging. Hemodynamic responses to AR are influenced by the interplay among cardiovascular properties, including left ventricular (LV) and aortic tissue properties, that cannot be measured directly. The aim of this study was to investigate how both echocardiographic measures of AR severity and the hemodynamic consequences of AR are influenced by LV and aortic stiffness. METHODS: AR was simulated using the CircAdapt computational model of the human cardiovascular system...
September 13, 2016: Journal of the American Society of Echocardiography
https://www.readbyqxmd.com/read/27609634/online-cardiac-output-estimation-during-transvalvular-left-ventricular-assistance
#14
Daniel Rüschen, Miriam Rimke, Jonas Gesenhues, Steffen Leonhardt, Marian Walter
BACKGROUND AND OBJECTIVES: Sufficient cardiac output is one of the main goals of ventricular assist device therapy. To date, there is no adequate method to estimate the combined amount of blood the native heart and a continuous-flow assist device pump through the circulatory system. This paper presents an approach to estimate total cardiac output based on the signals provided by optical pressure sensors mounted on the inlet and outlet of an Abiomed Impella CP pump. METHODS: Two Kalman filters were used in parallel for joint estimation of the aortic flow rate and the hydraulic resistance of the aortic valve...
August 30, 2016: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/27598222/surface-strains-of-porcine-tricuspid-valve-septal-leaflets-measured-in-ex-vivo-beating-hearts
#15
Keyvan Amini Khoiy, Dipankar Biswas, Thomas N Decker, Kourosh T Asgarian, Francis Loth, Rouzbeh Amini
Quantification of the tricuspid valve leaflets mechanical strain is important in order to understand valve pathophysiology and to develop effective treatment strategies. Many of the traditional methods used to dynamically open and close the cardiac valves in vitro via flow simulators require valve dissection. Recent studies, however, have shown that restriction of the atrioventricular valve annuli could significantly change their in-vivo deformation. For the first time, the porcine valve leaflets deformation was measured in a passive ex-vivo beating heart without isolating and remounting the valve annuli...
September 6, 2016: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/27597750/direct-aortic-access-for-transcatheter-aortic-valve-replacement-with-a-fully-repositionable-and-retrievable-nonmetallic-valve-system
#16
Hasan Bushnaq, Dietrich Metz, Asen Petrov, Stefan Frantz, Ulrich Hofmann, Christoph Raspé, Hendrik Treede
OBJECTIVE: The standard procedure of transcatheter aortic valve implantation involves transfemoral access. Nevertheless, the use of this access route is limited by the vessel diameter, calcification, and tortuosity, making a subgroup of patients ineligible for peripheral access. We report the first use of direct aortic transcatheter aortic valve implantation with the Direct Flow Medical valve (Direct Flow Medical, Inc, Santa Rosa, Calif) in 15 patients at the Halle-Wittenberg University...
August 12, 2016: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/27561388/the-influence-of-the-aortic-valve-angle-on-the-hemodynamic-features-of-the-thoracic-aorta
#17
Hojin Ha, Guk Bae Kim, Jihoon Kweon, Sang Joon Lee, Young-Hak Kim, Namkug Kim, Dong Hyun Yang
Since the first observation of a helical flow pattern in aortic blood flow, the existence of helical blood flow has been found to be associated with various pathological conditions such as bicuspid aortic valve, aortic stenosis, and aortic dilatation. However, an understanding of the development of helical blood flow and its clinical implications are still lacking. In our present study, we hypothesized that the direction and angle of aortic inflow can influence helical flow patterns and related hemodynamic features in the thoracic aorta...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27553639/spatial-expression-of-components-of-a-calcitonin-receptor-like-receptor-crl-signalling-system-crl-calcitonin-gene-related-peptide-adrenomedullin-adrenomedullin-2-intermedin-in-mouse-and-human-heart-valves
#18
Uwe Pfeil, Subhashini Bharathala, Ghulam Murtaza, Petra Mermer, Tamara Papadakis, Andreas Boening, Wolfgang Kummer
Heart valves are highly organized structures determining the direction of blood flow through the heart. Smooth muscle cells within the valve are thought to play an active role during the heart cycle, rather than being just passive flaps. The mature heart valve is composed of extracellular matrix (ECM), various differentiations of valvular interstitial cells (VIC), smooth muscle cells and overlying endothelium. VIC are important for maintaining the structural integrity of the valve, thereby affecting valve function and ECM remodelling...
August 23, 2016: Cell and Tissue Research
https://www.readbyqxmd.com/read/27494768/online-extraction-coupled-to-liquid-chromatography-analysis-ole-lc-eliminating-traditional-sample-preparation-steps-in-the-investigation-of-solid-complex-matrices
#19
Vinícius G Ferreira, Gabriel M Leme, Alberto J Cavalheiro, Cristiano S Funari
Current methods employed for the analysis of the chemical composition of solid matrices (such as plant, animal, or human tissues; soil; etc.) often require many sample treatment steps, including an extraction step with exclusively dedicated solvents. This work describes an optimized analytical setup in which the extraction of a solid sample is directly coupled to its analysis by high-performance liquid chromatography. This approach avoids (i) the use of pumps and valves other than those comprising the HPLC instrument, (ii) the use of solvents other than those of the mobile phase, and (iii) the need to stop the mobile phase flow at any time during the full analytical procedure...
September 6, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/27491617/late-presentation-of-a-semicomplete-occluded-right-coronary-artery-by-a-direct-flow-valve-preventing-interventional-therapy-for-st-segment-elevation-myocardial-infarction
#20
Christopher J Broyd, Michael Mullen, Man Fai Shiu
No abstract text is available yet for this article.
August 8, 2016: JACC. Cardiovascular Interventions
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