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Cardiovascular Engineering and Technology

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https://www.readbyqxmd.com/read/28070867/analytical-modeling-for-computing-lead-stress-in-a-novel-epicardial-micropacemaker
#1
Li Zhou, Yaniv Bar-Cohen, Raymond A Peck, Giorgio V Chirikian, Brett Harwin, Ramen H Chmait, Jay D Pruetz, Michael J Silka, Gerald E Loeb
Implantation and maintenance of a permanent cardiac pacing system in children remains challenging due to small patient size, congenital heart defects and somatic growth. We are developing a novel epicardial micropacemaker for children that can be implanted on the epicardium within the pericardial space via a minimally-invasive technique. The key design configurations include a novel open-coiled lead in which living tissue replaces the usual polymeric support for the coiled conductor. To better understand and be able to predict the behavior of the implanted lead, we performed a radiographic image-based modeling study on a chronic animal test...
January 9, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28070866/finite-element-analysis-of-patient-specific-mitral-valve-with-mitral-regurgitation
#2
Thuy Pham, Fanwei Kong, Caitlin Martin, Qian Wang, Charles Primiano, Raymond McKay, John Elefteriades, Wei Sun
Functional mitral regurgitation (FMR) is a significant complication of left ventricular dysfunction and strongly associated with a poor prognosis. In this study, we developed a patient-specific finite element (FE) model of the mitral apparatus in a FMR patient which included: both leaflets with thickness, annulus, chordae tendineae, and chordae insertions on the leaflets and origins on the papillary muscles. The FE model incorporated human age- and gender-matched anisotropic hyperelastic material properties, and MV closure at systole was simulated...
January 9, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27995570/hydrodynamic-assessment-of-aortic-valves-prepared-from-porcine-small-intestinal-submucosa
#3
Sharan Ramaswamy, Makensley Lordeus, Omkar V Mankame, Lilliam Valdes-Cruz, Steven Bibevski, Sarah M Bell, Ivan Baez, Frank Scholl
Infants and children born with severe cardiac valve lesions have no effective long term treatment options since currently available tissue or mechanical prosthetic valves have sizing limitations and no avenue to accommodate the growth of the pediatric patient. Tissue engineered heart valves (TEHVs) which could provide for growth, self-repair, infection resistance, and long-term replacement could be an ideal solution. Porcine small intestinal submucosa (PSIS) has recently emerged as a potentially attractive bioscaffold for TEHVs...
December 19, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27995569/fourier-transform-infrared-spectroscopic-imaging-derived-collagen-content-and-maturity-correlates-with-stress-in-the-aortic-wall-of-abdominal-aortic-aneurysm-patients
#4
Rabee Cheheltani, Joseph E Pichamuthu, Jayashree Rao, Justin S Weinbaum, Mohammad F Kiani, David A Vorp, Nancy Pleshko
Abdominal aortic aneurysm (AAA) is a degenerative disease of the aorta characterized by severe disruption of the structural integrity of the aortic wall and its major molecular constituents. From the early stages of disease, elastin in the aorta becomes highly degraded and is replaced by collagen. Questions persist as to the contribution of collagen content, quality and maturity to the potential for rupture. Here, using our recently developed Fourier transform infrared imaging spectroscopy (FT-IRIS) method, we quantified collagen content and maturity in the wall of AAA tissues in pairs of specimens with different wall stresses...
December 19, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27957718/dynamic-viscoelasticity-and-surface-properties-of-porcine-left-anterior-descending-coronary-arteries
#5
Hanna E Burton, Jenny M Freij, Daniel M Espino
The aim of this study was, for the first time, to measure and compare quantitatively the viscoelastic properties and surface roughness of coronary arteries. Porcine left anterior descending coronary arteries were dissected ex vivo. Viscoelastic properties were measured longitudinally using dynamic mechanical analysis, for a range of frequencies from 0.5 to 10 Hz. Surface roughness was calculated following three-dimensional reconstructed of surface images obtained using an optical microscope. Storage modulus ranged from 14...
December 12, 2016: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/27896659/the-relationship-between-pulsatile-flow-impingement-and-intraluminal-thrombus-deposition-in-abdominal-aortic-aneurysms
#6
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
#7
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/27848221/mechanical-properties-of-high-entropy-alloy-al0-1cocrfeni-for-peripheral-vascular-stent-application
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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/27778297/intrinsic-cell-stress-is-independent-of-organization-in-engineered-cell-sheets
#18
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
#19
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/27357301/modeling-current-density-maps-using-aliev-panfilov-electrophysiological-heart-model
#20
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
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