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Prosthetic heart valve design

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https://www.readbyqxmd.com/read/27915018/design-and-surface-immobilization-of-short-anti-biofilm-peptides
#1
Biswajit Mishra, Tamara Lushnikova, Radha M Golla, Xiuqing Wang, Guangshun Wang
: Short antimicrobial peptides are essential to keep us healthy and their lasting potency can inspire the design of new types of antibiotics. This study reports the design of a family of eight-residue tryptophan-rich peptides (TetraF2W) obtained by converting the four phenylalanines in temporin-SHf to tryptophans. The temporin-SHf template was identified from the antimicrobial peptide database (http://aps.unmc.edu/AP). Remarkably, the double arginine variant (TetraF2W-RR) was more effective in killing methicillin-resistant Staphylococcus aureus (MRSA) USA300, but less cytotoxic to human skin HaCat and kidney HEK293 cells, than the lysine-containing dibasic combinations (KR, RK and KK)...
November 30, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27873180/pledget-armed-sutures-affect-the-haemodynamic-performance-of-biologic-aortic-valve-substitutes-a-preliminary-experimental-and-computational-study
#2
Claudio Capelli, Chiara Corsini, Dario Biscarini, Francesco Ruffini, Francesco Migliavacca, Alfred Kocher, Guenther Laufer, Andrew M Taylor, Silvia Schievano, Martin Andreas, Gaetano Burriesci, Claus Rath
Surgical aortic valve replacement is the most common procedure of choice for the treatment of severe aortic stenosis. Bioprosthetic valves are traditionally sewed-in the aortic root by means of pledget-armed sutures during open-heart surgery. Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow rapid implantation, therefore reducing the duration and invasiveness of the intervention. Different effects on the hemodynamics were clinically reported associated with the two technologies...
November 21, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27873034/on-the-mechanics-of-transcatheter-aortic-valve-replacement
#3
Lakshmi P Dasi, Hoda Hatoum, Arash Kheradvar, Ramin Zareian, S Hamed Alavi, Wei Sun, Caitlin Martin, Thuy Pham, Qian Wang, Prem A Midha, Vrishank Raghav, Ajit P Yoganathan
Transcatheter aortic valves (TAVs) represent the latest advances in prosthetic heart valve technology. TAVs are truly transformational as they bring the benefit of heart valve replacement to patients that would otherwise not be operated on. Nevertheless, like any new device technology, the high expectations are dampened with growing concerns arising from frequent complications that develop in patients, indicating that the technology is far from being mature. Some of the most common complications that plague current TAV devices include malpositioning, crimp-induced leaflet damage, paravalvular leak, thrombosis, conduction abnormalities and prosthesis-patient mismatch...
November 21, 2016: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/27307007/effect-of-arched-leaflets-and-stent-profile-on-the-hemodynamics-of-tri-leaflet-flexible-polymeric-heart-valves
#4
Atieh Yousefi, David L Bark, Lakshmi P Dasi
Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations. Three models were created with height to diameter ratio of 0.6, 0.7, and 0.88. The other three models were designed by altering arch height to stent diameter ratio, to be 0, 0...
June 15, 2016: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/27140294/in-vitro-2d-piv-measurements-and-related-aperture-areas-of-tricuspid-bioprosthetic-mitral-valves-at-the-beginning-of-diastole
#5
Ovandir Bazan, Jayme Pinto Ortiz, Newton Kiyoshi Fukumasu, Antonio Luiz Pacifico, Jurandir Itizo Yanagihara
PURPOSE: Besides ventricular parameters, the design and angular orientation of a prosthetic heart valve induce a specific flow field. The aim of this study was to know the inflow characteristics of a left ventricular model (LVM), investigating the behavior of tricuspid bioprosthetic mitral valves in terms of velocity profiles and related valve aperture areas at the beginning of diastole, under different conditions. METHODS: 3 heart rates (HRs) were established in the LVM and each mitral bioprosthesis (27 and 31 mm diameter) was installed in 2 orientations, rotated by 180° ...
July 4, 2016: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/27026750/contemporary-outcomes-after-surgical-aortic-valve-replacement-with-bioprostheses-and-allografts-a-systematic-review-and-meta-analysis
#6
REVIEW
Simone A Huygens, Mostafa M Mokhles, Milad Hanif, Jos A Bekkers, Ad J J C Bogers, Maureen P M H Rutten-van Mölken, Johanna J M Takkenberg
Many observational studies have reported outcomes after surgical aortic valve replacement (AVR), but there are no recent systematic reviews and meta-analyses including all available bioprostheses and allografts. The objective of this study is to provide a comprehensive and up-to-date overview of the outcomes after AVR with bioprostheses and allografts reported in the last 15 years. We conducted a systematic literature review (PROSPERO register: CRD42015017041) of studies published between 2000-15. Inclusion criteria were observational studies or randomized controlled trials reporting on outcomes of AVR with bioprostheses (stented or stentless) or allografts, with or without coronary artery bypass grafting (CABG) or valve repair procedure, with study population size n ≥ 30 and mean follow-up length ≥5 years...
October 2016: European Journal of Cardio-thoracic Surgery
https://www.readbyqxmd.com/read/26919564/reynolds-shear-stress-for-textile-prosthetic-heart-valves-in-relation-to-fabric-design
#7
David L Bark, Atieh Yousefi, Marcio Forleo, Antoine Vaesken, Frederic Heim, Lakshmi P Dasi
The most widely implanted prosthetic heart valves are either mechanical or bioprosthetic. While the former suffers from thrombotic risks, the latter suffers from a lack of durability. Textile valves, alternatively, can be designed with durability and to exhibit hemodynamics similar to the native valve, lowering the risk for thrombosis. Deviations from native valve hemodynamics can result in an increased Reynolds Shear Stress (RSS), which has the potential to instigate hemolysis or shear-induced thrombosis. This study is aimed at characterizing flow in multiple textile valve designs with an aim of developing a low profile valve...
July 2016: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/26915473/vortex-ring-behavior-provides-the-epigenetic-blueprint-for-the-human-heart
#8
Per M Arvidsson, Sándor J Kovács, Johannes Töger, Rasmus Borgquist, Einar Heiberg, Marcus Carlsson, Håkan Arheden
The laws of fluid dynamics govern vortex ring formation and precede cardiac development by billions of years, suggesting that diastolic vortex ring formation is instrumental in defining the shape of the heart. Using novel and validated magnetic resonance imaging measurements, we show that the healthy left ventricle moves in tandem with the expanding vortex ring, indicating that cardiac form and function is epigenetically optimized to accommodate vortex ring formation for volume pumping. Healthy hearts demonstrate a strong coupling between vortex and cardiac volumes (R(2) = 0...
2016: Scientific Reports
https://www.readbyqxmd.com/read/26786673/effect-of-heart-rate-on-the-hemodynamics-of-bileaflet-mechanical-heart-valves-prostheses-st-jude-medical-in-the-aortic-position-and-in-the-opening-phase-a-computational-study
#9
Mehdi Jahandardoost, Guy Fradet, Hadi Mohammadi
To date, to the best of the authors' knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70-72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60-150 beats/min, was studied in the opening phase...
March 2016: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/26781657/management-of-coronary-artery-disease-and-conduction-abnormalities-in-transcatheter-aortic-valve-implantation
#10
Anna Kostopoulou, Panagiotis Karyofillis, Efthimios Livanis, George Karavolias, George Theodorakis, John Paraskevaides, Vassilis Voudris
Transcatheter aortic valve replacement (TAVR) is an expanding, catheter-based technology that allows the implantation of a prosthetic valve without requiring open heart surgery for the treatment of severe aortic stenosis (AS). The frequency of coronary artery disease (CAD) in patients (pts) with severe AS undergoing surgical treatment ranges from 30 to 50 %. This tends to be higher in pts undergoing TAVR with a prevalence of 49-76 % and is more prevalent with older age and the fact that TAVR is commonly performed in high-risk groups with more advanced cardiovascular disease...
February 2016: Current Treatment Options in Cardiovascular Medicine
https://www.readbyqxmd.com/read/26737004/3d-velocity-field-characterization-of-prosthetic-heart-valve-with-two-different-valve-testers-by-means-of-stereo-piv
#11
Giuseppe D'Avenio, Mauro Grigioni, Carla Daniele, Umberto Morbiducci, Kathrin Hamilton
BACKGROUND: Prosthetic heart valves can be associated to mechanical loading of blood, potentially linked to complications (hemolysis and thrombogenicity) which can be clinically relevant. In order to test such devices in pulsatile mode, pulse duplicators (PDs) have been designed and built according to different concepts. This study was carried out to compare anemometric measurements made on the same prosthetic device, with two widely used PDs. METHODS: The valve (a 27-mm bileaflet valve) was mounted in the aortic section of the PD...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/26736254/effect-of-valsalva-in-the-pulmonary-prosthetic-conduit-valve-on-hemodynamic-function-in-a-mock-circulatory-system
#12
Yusuke Tsuboko, Yasuyuki Shiraishi, Akihiro Yamada, Tomoyuki Yambe, Satoshi Matsuo, Yoshikatsu Saiki, Masaaki Yamagishi
Pulmonary conduit valves are used as one of the surgical treatment methods of congenital heart diseases. We have been designing a sophisticated pulmonary conduit valve for the right ventricular outflow tract reconstruction in pediatric patients. In this study, two types of polyester grafts with or without bulging structures for the conduit valves were used and evaluated from the hemodynamic point of view focusing on the application of these conduit valves in the grown-up congenital heart failure patients. We examined valvular function in the originally developed pulmonary mock circulatory system, which consisted of a pneumatic driven right ventricular model, a pulmonary valve chamber, and an elastic pulmonary compliance model with peripheral vascular resistance units...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/26731290/anticoagulation-for-prosthetic-heart-valves-unresolved-questions-requiring-answers
#13
REVIEW
Bobby Yanagawa, Richard P Whitlock, Subodh Verma, Bernard J Gersh
PURPOSE OF REVIEW: The efficacy of anticoagulation for valvular prostheses is the result of a delicate balance between the risk of thromboembolic (TE) events and bleeding. Here, we review data on anticoagulation for valve prostheses with a focus on clinical trials that address key unanswered questions. RECENT FINDINGS: There are several unanswered questions in the field of prosthetic valve anticoagulation, including: optimal TE prophylaxis in the short term for bioprostheses, optimal TE prophylaxis following transcatheter aortic valve implantation, the safety and efficacy of lower levels of anticoagulation with the bileaflet mechanical prosthesis, the role of aspirin for patients with mechanical prostheses, and the management of anticoagulation for mechanical valves in pregnancy...
March 2016: Current Opinion in Cardiology
https://www.readbyqxmd.com/read/26689146/fluid-dynamic-characterization-of-a-polymeric-heart-valve-prototype-poli-valve-tested-under-continuous-and-pulsatile-flow-conditions
#14
Francesco De Gaetano, Marta Serrani, Paola Bagnoli, Jacob Brubert, Joanna Stasiak, Geoff D Moggridge, Maria Laura Costantino
PURPOSE: Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves...
November 2015: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/26604056/a-new-transcatheter-aortic-valve-replacement-system-for-predominant-aortic-regurgitation-implantation-of-the-j-valve-and-early-outcome
#15
Lai Wei, Huan Liu, Liming Zhu, Ye Yang, Jiayu Zheng, Kefang Guo, Hong Luo, Weipeng Zhao, Xue Yang, Aikebaier Maimaiti, Chunsheng Wang
OBJECTIVES: This study introduces a newly designed transcatheter aortic valve system, the J-Valve system, and evaluates its application in patients with predominant aortic regurgitation without significant valve calcification. We also report the early results of one of the first series of transapical implantations of this device and aim to offer guidance on the technical aspects of the procedure. BACKGROUND: Transcatheter aortic valve replacement (TAVR) has been widely used in high-risk patients for surgical aortic valve replacement...
December 21, 2015: JACC. Cardiovascular Interventions
https://www.readbyqxmd.com/read/26329461/hemodynamic-and-thrombogenic-analysis-of-a-trileaflet-polymeric-valve-using-a-fluid-structure-interaction-approach
#16
Filippo Piatti, Francesco Sturla, Gil Marom, Jawaad Sheriff, Thomas E Claiborne, Marvin J Slepian, Alberto Redaelli, Danny Bluestein
Surgical valve replacement in patients with severe calcific aortic valve disease using either bioprosthetic or mechanical heart valves is still limited by structural valve deterioration for the former and thrombosis risk mandating anticoagulant therapy for the latter. Prosthetic polymeric heart valves have the potential to overcome the inherent material and design limitations of these valves, but their development is still ongoing. The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach...
October 15, 2015: Journal of Biomechanics
https://www.readbyqxmd.com/read/25920812/in-vitro-investigation-of-the-hemodynamics-of-transcatheter-heterotopic-valves-implantation-in-the-cavo-atrial-junction
#17
Munirah Ismail, Foad Kabinejadian, Yen Ngoc Nguyen, Edgar Tay, Sangho Kim, Hwa Liang Leo
Severe tricuspid regurgitation (TR) is life-threatening but is often undertreated. Many patients with severe TR are denied heart valve replacement surgery because their old age or comorbidities predispose them to a higher risk of surgical complications associated with open-heart surgery. With the advent of transcatheter technology, it is now possible to deliver the valve to the desired location without the need for open-heart surgery. However, presently, there is no commercially available transcatheter tricuspid valve...
September 2015: Artificial Organs
https://www.readbyqxmd.com/read/25911252/characterization-of-the-toughness-and-elastic-properties-of-fresh-and-cryopreserved-arteries
#18
Nastaran Shahmansouri, Raymond Cartier, Rosaire Mongrain
Surgical interventions are used to manage severe complications of heart valve diseases and to prevent the eventual rupture of an aortic aneurysm. Soft-tissue allografts, xenografts, and prosthetic grafts are used in these interventions; however, there are pre-surgical difficulties and post-surgical complications in using these grafts. One of these is the rupture potential of cryopreserved allografts at the time of transplantation and/or after the thawing process for the cryopreserved tissue. Moreover, a number of clinical observations report the patency of prosthetic grafts and aneurysm of cryopreserved allografts after the transplantation...
July 16, 2015: Journal of Biomechanics
https://www.readbyqxmd.com/read/25833999/a-novel-computational-model-for-the-hemodynamics-of-bileaflet-mechanical-valves-in-the-opening-phase
#19
Mehdi Jahandardoost, Guy Fradet, Hadi Mohammadi
A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous...
March 2015: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/25691396/a-strain-based-model-for-mechanical-hemolysis-based-on-a-coarse-grained-red-blood-cell-model
#20
Hussein M Ezzeldin, Marco D de Tullio, Marcos Vanella, Santiago D Solares, Elias Balaras
Mechanical hemolysis is a major concern in the design of cardiovascular devices, such as prosthetic heart valves and ventricular assist devices. The primary cause of mechanical hemolysis is the impact of the device on the local blood flow, which exposes blood elements to non-physiologic conditions. The majority of existing hemolysis models correlate red blood cell (RBC) damage to the imposed fluid shear stress and exposure time. Only recently more realistic, strain-based models have been proposed, where the RBC's response to the imposed hydrodynamic loading is accounted for...
June 2015: Annals of Biomedical Engineering
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