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Cardiovascular Engineering and Technology

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https://www.readbyqxmd.com/read/27896659/the-relationship-between-pulsatile-flow-impingement-and-intraluminal-thrombus-deposition-in-abdominal-aortic-aneurysms
#1
Richard J Lozowy, David C S Kuhn, Annie A Ducas, April J Boyd
Direct numerical simulations were performed on four patient-specific abdominal aortic aneurysm (AAA) geometries and the resulting pulsatile blood flow dynamics were compared to aneurysm shape and correlated with intraluminal thrombus (ILT) deposition. For three of the cases, turbulent vortex structures impinged/sheared along the anterior wall and along the posterior wall a zone of recirculating blood formed. Within the impingement region the AAA wall was devoid of ILT and remote to this region there was an accumulation of ILT...
November 28, 2016: Cardiovascular Engineering and Technology
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/27778297/intrinsic-cell-stress-is-independent-of-organization-in-engineered-cell-sheets
#3
Inge A E W van Loosdregt, Sylvia Dekker, Patrick W Alford, Cees W J Oomens, Sandra Loerakker, Carlijn V C Bouten
Understanding cell contractility is of fundamental importance for cardiovascular tissue engineering, due to its major impact on the tissue's mechanical properties as well as the development of permanent dimensional changes, e.g., by contraction or dilatation of the tissue. Previous attempts to quantify contractile cellular stresses mostly used strongly aligned monolayers of cells, which might not represent the actual organization in engineered cardiovascular tissues such as heart valves. In the present study, therefore, we investigated whether differences in organization affect the magnitude of intrinsic stress generated by individual myofibroblasts, a frequently used cell source for in vitro engineered heart valves...
October 24, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27709350/effect-of-side-specific-valvular-shear-stress-on-the-content-of-extracellular-matrix-in-aortic-valves
#4
Napachanok Mongkoldhumrongkul, Najma Latif, Magdi H Yacoub, Adrian H Chester
Responses of valve endothelial cells (VECs) to shear stresses are important for the regulation of valve durability. However, the effect of flow patterns subjected to VECs on the opposite surfaces of the valves on the production of extracellular matrix (ECM) has not yet been investigated. This study aims to investigate the response of side-specific flow patterns, in terms of ECM synthesis and/or degradation in porcine aortic valves. Aortic and ventricular sides of aortic valve leaflets were exposed to oscillatory and laminar flow generated by a Cone-and-Plate machine for 48 h...
October 5, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27848221/mechanical-properties-of-high-entropy-alloy-al0-1cocrfeni-for-peripheral-vascular-stent-application
#5
Karthik Alagarsamy, Aleksandra Fortier, Mageshwari Komarasamy, Nilesh Kumar, Atif Mohammad, Subhash Banerjee, Hai-Chao Han, Rajiv S Mishra
High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27844463/fluid-structure-interaction-study-of-transcatheter-aortic-valve-dynamics-using-smoothed-particle-hydrodynamics
#6
Wenbin Mao, Kewei Li, Wei Sun
Computational modeling of heart valve dynamics incorporating both fluid dynamics and valve structural responses has been challenging. In this study, we developed a novel fully-coupled fluid-structure interaction (FSI) model using smoothed particle hydrodynamics (SPH). A previously developed nonlinear finite element (FE) model of transcatheter aortic valves (TAV) was utilized to couple with SPH to simulate valve leaflet dynamics throughout the entire cardiac cycle. Comparative simulations were performed to investigate the impact of using FE-only models vs...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27743349/computational-tracking-of-shear-mediated-platelet-interactions-with-von-willebrand-factor
#7
Adam Ralph, Martin Somers, Jonathan Cowman, Bruno Voisin, Emma Hogan, Hannah Dunne, Eimear Dunne, Barry Byrne, Nigel Kent, Antonio J Ricco, Dermot Kenny, Simon Wong
The imaging of shear-mediated dynamic platelet behavior interacting with surface-immobilized von Willebrand factor (vWF) has tremendous potential in characterizing changes in platelet function for clinical diagnostics purposes. However, the imaging output, a series of images representing platelets adhering and rolling on the surface, poses unique, non-trivial challenges for software algorithms that reconstruct the positional trajectories of platelets. We report on an algorithm that tracks platelets using the output of such flow run experiments, taking into account common artifacts encountered by previously-published methods, and we derive seven key metrics of platelet dynamics that can be used to characterize platelet function...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27730533/improved-blood-pressure-prediction-using-systolic-flow-correction-of-pulse-wave-velocity
#8
Jeffrey S Lillie, Alexander S Liberson, David A Borkholder
Hypertension is a significant worldwide health issue. Continuous blood pressure monitoring is important for early detection of hypertension, and for improving treatment efficacy and compliance. Pulse wave velocity (PWV) has the potential to allow for a continuous blood pressure monitoring device; however published studies demonstrate significant variability in this correlation. In a recently presented physics-based mathematical model of PWV, flow velocity is additive to the classic pressure wave as estimated by arterial material properties, suggesting flow velocity correction may be important for cuff-less non-invasive blood pressure measures...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27573761/effects-of-leaflet-design-on-transvalvular-gradients-of-bioprosthetic-heart-valves
#9
Yaghoub Dabiri, Janet Ronsky, Imtiaz Ali, Ameen Basha, Alisha Bhanji, Kishan Narine
Bioprosthetic aortic valves (BAVs) are becoming the prostheses of choice in heart valve replacement. The objective of this paper is to assess the effects of leaflet geometry on the mechanics and hemodynamics of BAVs in a fluid structure interaction model. The curvature and angle of leaflets were varied in 10 case studies whereby the following design parameters were altered: a circular arch, a line, and a parabola for the radial curvature, and a circular arch, a spline, and a parabola for the circumferential curvature...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27552824/mathematical-modeling-and-simulation-of-an-occlusion-device-in-a-blood-vessel
#10
Vaibhavi A Sonetha, Jayesh R Bellare
An occlusion device is placed in an abnormal opening of the heart or its surrounding vessels to regain normal blood flow. There are various occlusion devices available for treatment of various congenital heart defects like PDA, ASD, etc. However, they have limitations like residual shunting, erosion of tissue, displacement and breakage of device, thrombus formation and sudden death. To improve efficiency and to reduce failure of occlusion devices, it is important to simulate blood flow through defect before and after placement of device...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27507280/biomechanical-behavior-of-bioprosthetic-heart-valve-heterograft-tissues-characterization-simulation-and-performance
#11
REVIEW
Joao S Soares, Kristen R Feaver, Will Zhang, David Kamensky, Ankush Aggarwal, Michael S Sacks
The use of replacement heart valves continues to grow due to the increased prevalence of valvular heart disease resulting from an ageing population. Since bioprosthetic heart valves (BHVs) continue to be the preferred replacement valve, there continues to be a strong need to develop better and more reliable BHVs through and improved the general understanding of BHV failure mechanisms. The major technological hurdle for the lifespan of the BHV implant continues to be the durability of the constituent leaflet biomaterials, which if improved can lead to substantial clinical impact...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27443841/pulse-duplicator-hydrodynamic-testing-of-bioengineered-biological-heart-valves
#12
Eric E Buse, Stephen L Hilbert, Richard A Hopkins, Gabriel L Converse
There are many heart valve replacements currently available on the market; however, these devices are not ideal for pediatric patients with congenital heart valve defects. Decellularized valve substitutes offer potential for improved clinical outcomes and require pre-clinical testing guidelines and testing systems suitable for non-crosslinked, biological heart valves. The objective of this study was to assess the hydrodynamic performance of intact, bioengineered pulmonary valves using a custom pulse duplicator capable of testing intact biological valved conduits...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27443840/computational-model-of-drug-coated-balloon-delivery-in-a-patient-specific-arterial-vessel-with-heterogeneous-tissue-composition
#13
Prashanta K Mandal, Sarifuddin, Vijaya B Kolachalama
Balloon angioplasty followed by local delivery of antiproliferative drugs to target tissue is increasingly being considered for the treatment of obstructive arterial disease, and yet there is much to appreciate regarding pharmacokinetics in arteries of non-uniform disease. We developed a computational model capable of simulating drug-coated balloon delivery to arteries of heterogeneous tissue composition comprising healthy tissue, as well as regions of fibrous, fibro-fatty, calcified and necrotic core lesions...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27440112/simulation-of-anastomosis-in-coronary-artery-bypass-surgery
#14
Hadi Mohammadi, Bret Nestor, Guy Fradet
Developing cardiac surgical skills and experience takes years of practice. Cardiac trainees need to develop technical proficiency in order to enhance quality of care and patient safety. Simulation-based models are common resources for teaching procedural skills in both undergraduate and postgraduate medical education. Suitable and accessible educational platforms can play a progressively important role in the training process for young surgeons in the area of cardiac surgery. Coronary artery bypass graft (CABG) surgery consists of a wide range of pathologic anatomies and surgical techniques...
December 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27357301/modeling-current-density-maps-using-aliev-panfilov-electrophysiological-heart-model
#15
M Beheshti, F H Foomany, K Magtibay, S Masse, P Lai, J Asta, D A Jaffray, K Nanthakumar, S Krishnan, K Umapathy
Most existing studies of cardiac arrhythmia rely on surface measurements through optical or electrical mapping techniques. Current density imaging (CDI) is a method which enables us to study current pathways inside the tissue. However, this method entails implementation complexities for beating ex vivo hearts. Hence, this work presents an approach to simulate and study the current distributions in different cardiac electrophysiological states. The results are corroborated by experimental data, and they indicate that different states were distinguishable...
September 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27357300/an-experimental-and-computational-study-on-the-effect-of-caval-valved-stent-oversizing
#16
Munirah Ismail, Gideon Praveen Kumar, Foad Kabinejadian, Yen Ngoc Nguyen, Fangsen Cui, Edgar Lik Wui Tay, Hwa Liang Leo
Heterotopic implantation of transcatheter tricuspid valve is a new treatment option for tricuspid regurgitation. Transcatheter tricuspid valves are implanted onto the cavoatrial junction in order to avoid the challenging task of anchoring the valve onto the complex tricuspid valve annulus. However, little is known about optimum extent of oversizing of the valved stent in a vena cava. In this study, we implanted valves of the same diameter onto the larger sized inferior vena cava (IVC) and a smaller sized superior vena cava (SVC)...
September 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27350138/annulus-tension-on-the-tricuspid-valve-an-in-vitro-study
#17
Avik Basu, Zhaoming He
Annulus tension (AT) is defined as leaflet tension per unit length of the annulus circumference. AT was investigated to understand tricuspid valve (TV) annulus mechanics. Ten porcine TVs were mounted on a right ventricle rig with an annulus plate to simulate TV closure. The TVs were mounted on the annulus plate in a normal and dilated TV annulus sizes, and closed under transvalvular pressure of 40 mmHg with the annulus held peripherally by wires. Anterior papillary muscle (PM) and septal PM were displaced in the dilated annulus...
September 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27350137/analysis-of-transitional-and-turbulent-flow-through-the-fda-benchmark-nozzle-model-using-laser-doppler-velocimetry
#18
Joshua O Taylor, Bryan C Good, Anthony V Paterno, Prasanna Hariharan, Steven Deutsch, Richard A Malinauskas, Keefe B Manning
Transitional and turbulent flow through a simplified medical device model is analyzed as part of the FDA's Critical Path Initiative, designed to improve the process of bringing medical products to market. Computational predictions are often used in the development of devices and reliable in vitro data is needed to validate computational results, particularly estimations of the Reynolds stresses that could play a role in damaging blood elements. The high spatial resolution of laser Doppler velocimetry (LDV) is used to collect two component velocity data within the FDA benchmark nozzle model...
September 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27333887/alterations-of-blood-flow-through-arteries-following-atherectomy-and-the-impact-on-pressure-variation-and-velocity
#19
Brian D Plourde, Lauren J Vallez, Biyuan Sun, Brittany B Nelson-Cheeseman, John P Abraham, Cezar S Staniloae
Simulations were made of the pressure and velocity fields throughout an artery before and after removal of plaque using orbital atherectomy plus adjunctive balloon angioplasty or stenting. The calculations were carried out with an unsteady computational fluid dynamic solver that allows the fluid to naturally transition to turbulence. The results of the atherectomy procedure leads to an increased flow through the stenotic zone with a coincident decrease in pressure drop across the stenosis. The measured effect of atherectomy and adjunctive treatment showed decrease the systolic pressure drop by a factor of 2...
September 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27177747/time-resolved-micro-piv-in-the-pivoting-area-of-the-triflo-mechanical-heart-valve
#20
Bernhard M Vennemann, Thomas Rösgen, Thierry P Carrel, Dominik Obrist
The Lapeyre-Triflo FURTIVA valve aims at combining the favorable hemodynamics of bioprosthetic heart valves with the durability of mechanical heart valves (MHVs). The pivoting region of MHVs is hemodynamically of special interest as it may be a region of high shear stresses, combined with areas of flow stagnation. Here, platelets can be activated and may form a thrombus which in the most severe case can compromise leaflet mobility. In this study we set up an experiment to replicate the pulsatile flow in the aortic root and to study the flow in the pivoting region under physiological hemodynamic conditions (CO = 4...
September 2016: Cardiovascular Engineering and Technology
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