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Direct flow valve

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https://www.readbyqxmd.com/read/29098290/fluid-structure-interaction-models-of-bicuspid-aortic-valves-the-effects-of-non-fused-cusp-angles
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28883786/arterial-pulsations-cannot-drive-intramural-periarterial-drainage-significance-for-a%C3%AE-drainage
#14
Alexandra K Diem, Matthew MacGregor Sharp, Maureen Gatherer, Neil W Bressloff, Roxana O Carare, Giles Richardson
Alzheimer's Disease (AD) is the most common form of dementia and to date there is no cure or efficient prophylaxis. The cognitive decline correlates with the accumulation of amyloid-β (Aβ) in the walls of capillaries and arteries. Our group has demonstrated that interstitial fluid and Aβ are eliminated from the brain along the basement membranes of capillaries and arteries, the intramural periarterial drainage (IPAD) pathway. With advancing age and arteriosclerosis, the stiffness of arterial walls, this pathway fails in its function and Aβ accumulates in the walls of arteries...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28860548/valley-filter-and-valve-effect-by-strong-electrostatic-potentials-in-graphene
#15
Juan Juan Wang, Su Liu, Jun Wang, Jun-Feng Liu
We report a theoretical study on the valley-filter and valley-valve effects in the monolayer graphene system by using electrostatic potentials, which are assumed to be electrically controllable. Based on a lattice model, we find that a single extremely strong electrostatic-potential barrier, with its strength exceeding the hopping energy of electrons, will significantly block one valley but allow the opposite valley flowing in the system, and this is dependent on the sign of the potential barrier as well as the flowing direction of electrons...
August 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28858090/prenatal-ultrasonic-diagnosis-of-absent-pulmonary-valve-syndrome-a-case-report
#16
Wen-Jun Zhang, Zhong-Lei Zhang, Jun-Jie Chang, Xiao-Yu Song
RATIONALE: Absent pulmonary valve syndrome (APVS) is a rare congenital heart disease that is often associated with tetralogy of Fallot (TOF). Here, we report 2 cases of APVS associated with TOF diagnosed via fetal echocardiography and discuss their specific ultrasonographic characteristics. PATIENT CONCERNS: Two pregnant women with suspicion of fetal heart anomaly were referred from their local hospitals to our hospital for fetal malformation screening and detailed fetal echocardiography...
September 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28852976/experimental-study-of-right-ventricular-hemodynamics-after-tricuspid-valve-replacement-therapies-to-treat-tricuspid-regurgitation
#17
Yen Ngoc Nguyen, Munirah Ismail, Foad Kabinejadian, Chi Wei Ong, Edgar Lik Wui Tay, Hwa Liang Leo
The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR). In some cases of FTR, prosthetic valve replacement is typically considered when concomitant organic components or significant geometrical distortions are involved in the pathology of the tricuspid valve. However, little is known of the performance of current devices in the right heart circulation. In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated...
August 29, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28838487/cardioscopically-guided-beating-heart-surgery-paravalvular-leak-repair
#18
Benoit Rosa, Zurab Machaidze, Margherita Mencattelli, Sunil Manjila, Borami Shin, Karl Price, Michael A Borger, Vinod Thourani, Pedro Del Nido, David W Brown, Christopher W Baird, John E Mayer, Pierre E Dupont
PURPOSE: There remains a paucity of direct visualization techniques for beating-heart intracardiac procedures. To address this need, we evaluated a novel cardioscope in the context of aortic paravalvular leaks (PVLs) localization and closure. DESCRIPTION: A porcine aortic PVL model was created using a custom-made bioprosthetic valve, and PVL presence was verified by epicardial echocardiography. Transapical delivery of occlusion devices guided solely by cardioscopy was attempted 13 times in a total of three pigs...
September 2017: Annals of Thoracic Surgery
https://www.readbyqxmd.com/read/28837613/impact-of-sheath-diameter-of-different-sheath-types-on-vascular-complications-and-mortality-in-transfemoral-tavi-approaches-using-the-proglide-closure-device
#19
Zisis Dimitriadis, Werner Scholtz, Stephan M Ensminger, Cornelia Piper, Thomas Bitter, Marcus Wiemer, Marios Vlachojannis, Jochen Börgermann, Lothar Faber, Dieter Horstkotte, Jan Gummert, Smita Scholtz
OBJECTIVE: Evaluation of the impact of the sheath diameter on vascular complications and mortality in transfemoral aortic valve implantation. METHOD: Between 2012 and 2014, 183 patients underwent the procedure using a sheath diameter of 18-24 F. This collective was divided into two groups: group 1, with a sheath diameter of 18F (G1, n = 94), consisted of patients with 18F Medtronic Sentrant and 18 F Direct Flow sheaths, and group 2 with a sheath diameter of 19-24 F (G2, n = 89) consisted of patients with Edwards expandable e-sheath and Solopath sheaths...
2017: PloS One
https://www.readbyqxmd.com/read/28831197/a-pulsed-air-model-of-blue-whale-b-call-vocalizations
#20
R P Dziak, J H Haxel, T-K Lau, S Heimlich, J Caplan-Auerbach, D K Mellinger, H Matsumoto, B Mate
Blue whale sound production has been thought to occur by Helmholtz resonance via air flowing from the lungs into the upper respiratory spaces. This implies that the frequency of blue whale vocalizations might be directly proportional to the size of their sound-producing organs. Here we present a sound production mechanism where the fundamental and overtone frequencies of blue whale B calls can be well modeled using a series of short-duration (<1 s) wavelets. We propose that the likely source of these wavelets are pneumatic pulses caused by opening and closing of respiratory valves during air recirculation between the lungs and laryngeal sac...
August 22, 2017: Scientific Reports
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