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Cardiovascular Engineering and Technology

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https://www.readbyqxmd.com/read/29150791/16-channel-flexible-system-to-measure-electrophysiological-properties-of-bioengineered-hearts
#1
Betsy H Salazar, Kristopher A Hoffman, Anilkumar K Reddy, Sridhar Madala, Ravi K Birla
As tissue engineering continues to mature, it is necessary to develop new technologies that bring insight into current paradigms and guide improvements for future experiments. To this end, we have developed a system to characterize our bioartificial heart model and compare them to functional native structures. In the present study, the hearts of adult Sprague-Dawley were decellularized resulting in a natural three-dimensional cardiac scaffold. Neonatal rat primary cardiac cells were then cultured within a complex 3D fibrin gel, forming a 3-dimensional cardiac construct, which was sutured to the acellular scaffold and suspended in media for 24-48 h...
November 17, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/29134471/the-impact-of-heat-treatment-on-porcine-heart-valve-leaflets
#2
R Glenn Hepfer, Peng Chen, Kelvin G M Brockbank, Alyce L Jones, Amanda K Burnette, Zhen Chen, Elizabeth D Greene, Lia H Campbell, Hai Yao
The purpose of this study was to determine the impact of elevated temperature exposure in tissue banking on soft tissues. A secondary objective was to determine the relative ability of various assays to detect changes in soft tissues due to temperature deviations. Porcine pulmonary heart valve leaflets exposed to 37 °C were compared with those incubated at 52 and 67 °C for 10, 30 and 100 min. The analytical methods consisted of (1) viability assessment using the resazurin assay, (2) collagen content using the Sircol assay, and (3) permeability assessment using an electrical conductivity assay...
November 13, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/29124548/development-of-an-experimental-and-digital-cardiovascular-arterial-model-for-transient-hemodynamic-and-postural-change-studies-a-preliminary-framework-analysis
#3
Rodward L Hewlin, John P Kizito
The ultimate goal of the present work is to aid in the development of tools to assist in the treatment of cardiovascular disease. Gaining an understanding of hemodynamic parameters for medical implants allow clinicians to have some patient-specific proposals for intervention planning. In the present work an experimental and digital computational fluid dynamics (CFD) arterial model consisting of a number of major arteries (aorta, carotid bifurcation, cranial, femoral, jejunal, and subclavian arteries) were fabricated to study: (1) the effects of local hemodynamics (flow parameters) on global hemodynamics (2) the effects of transition from bedrest to upright position (postural change) on hemodynamics, and (3) diffusion of dye (medical drug diffusion simulation) in the arterial system via experimental and numerical techniques...
November 9, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28940163/predicting-the-dimensions-of-an-intracardiac-partial-assist-pump-for-percutaneous-delivery-by-analytical-and-numerical-methods
#4
Robert E Smith, P Alex Smith, William E Cohn
A minimally invasive ventricular assist device is under development for percutaneous insertion into the left atrium via transseptal access from the right atrium (RA). This study aimed to mathematically describe the vascular anatomy along possible insertion pathways to determine the device's maximum outer dimensions. We developed 2-dimensional mathematical models describing the vascular anatomy to the RA from three access points: subclavian vein (SCV), internal jugular vein (IJV), and femoral vein (FV). All pathways terminated by turning from the superior or inferior vena cava (SVC/IVC) into the RA...
September 22, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28913763/a-patient-specific-three-dimensional-hemodynamic-model-of-the-circle-of-willis
#5
Hamed Rezaie, Ali Ashrafizadeh, Afsaneh Mojra
Circle of Willis (CoW) is one of the most important cerebral arteries in the human body and various attempts have been made to study the hemodynamic of blood flow in this vital part of the brain. In the present study, blood flow in a patient specific CoW is numerically modeled to predict disease-prone regions of the CoW. Medical images and computer aided design software are used to construct a realistic three-dimensional model of the CoW for this particular case. The arteries are considered as elastic conduits and the interactions between arterial walls and the blood flow are taken into account...
September 14, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28884368/anatomical-and-optical-properties-of-atrial-tissue-search-for-a-suitable-animal-model
#6
Narine Muselimyan, Mohammed Al Jishi, Huda Asfour, Luther Swift, Narine A Sarvazyan
The purpose of this study was to evaluate structural and optical properties of atrial tissue from common animal models and to compare it with human atria. We aimed to do this in a format that will be useful for development of better ablation tools and/or new means for visualizing atrial lesions. Human atrial tissue from clinically relevant age group was compared and contrasted with atrial tissue of large animal models commonly available for research purposes. These included pigs, sheep, dogs and cows. The presented data include area measurements of smooth atrial surface available for ablation and estimates of thickness of collagen and muscle for five different species...
September 7, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28852976/experimental-study-of-right-ventricular-hemodynamics-after-tricuspid-valve-replacement-therapies-to-treat-tricuspid-regurgitation
#7
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/28849552/regenerative-stem-cell-therapy-optimization-via-tissue-engineering-in-heart-failure-with-reduced-ejection-fraction
#8
REVIEW
Mehmet Alkan, Raef Madanieh, Niel N Shah, Muhammad U Dogar, Parin N Shah, Sameera Ishtiaq, Constantine E Kosmas, Timothy J Vittorio
The prevalence of heart failure (HF) is continuously rising in both the industrialized and non-industrialized nations. Despite current therapeutic advances, prognosis of HF patients remains poor. Presently, therapeutic pharmacological and device strategies for HF with reduced ejection fraction (HFrEF) are mostly palliative and do not induce regeneration of lost myocardial tissue. Stem cell therapy has demonstrated promising results in clinical studies by promoting myocardial restoration in HFrEF subjects. Despite decades of investigation, many challenges remain unanswered to the widespread clinical application of stem cell therapy for HFrEF...
August 28, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28795379/editorial-special-issue-on-vascular-access-towards-improving-vascular-access
#9
EDITORIAL
Michael T Walsh, James E Moore
No abstract text is available yet for this article.
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28752375/biological-and-physical-factors-involved-in-the-maturation-of-arteriovenous-fistula-for-hemodialysis
#10
Andrea Remuzzi, Michela Bozzetto
One of the most important limitations of hemodialysis (HD) treatment is the vascular access (VA) that is used to connect the patient's blood vessels to the extracorporeal circulation. The arteriovenous fistula (AVF) obtained with native vessels is the VA of choice for the low incidence of infections and the long-term patency, but it is affected by high incidence of non-maturation or primary failure. Before use for cannulation, AVF must undergo vascular remodeling, with progressive increase in vessel diameter, to accommodate the increase in blood flow...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28748414/the-effect-of-arterial-curvature-on-blood-flow-in-arterio-venous-fistulae-realistic-geometries-and-pulsatile-flow
#11
L Grechy, F Iori, R W Corbett, W Gedroyc, N Duncan, C G Caro, P E Vincent
Arterio-Venous Fistulae (AVF) are regarded as the "gold standard" method of vascular access for patients with End-Stage Renal Disease (ESRD) who require haemodialysis. However, up to 60% of AVF do not mature, and hence fail, as a result of Intimal Hyperplasia (IH). Unphysiological flow and oxygen transport patterns, associated with the unnatural and often complex geometries of AVF, are believed to be implicated in the development of IH. Previous studies have investigated the effect of arterial curvature on blood flow in AVF using idealized planar AVF configurations and non-pulsatile inflow conditions...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28744783/towards-the-identification-of-hemodynamic-parameters-involved-in-arteriovenous-fistula-maturation-and-failure-a-review
#12
Marco Franzoni, Michael T Walsh
Native arteriovenous fistulas have a high failure rate mainly due to the lack of maturation and uncontrolled neo-intimal hyperplasia development. Newly established hemodynamics is thought to be central in driving the fistula fate, after surgical creation. To investigate the effects of realistic wall shear stress stimuli on endothelial cells, an in vitro approach is necessary in order to reduce the complexity of the in vivo environment. After a systematic review, realistic WSS waveforms were selected and analysed in terms of magnitude, temporal gradient, presence of reversing phases (oscillatory shear index, OSI) and frequency content (hemodynamics index, HI)...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28721509/maintaining-patency-of-vascular-access-for-haemodialysis
#13
Nicholas Inston, J Al Shakarchi, A Khawaja, R Jones
All types of vascular access, a necessity for haemodialysis, are prone to thrombosis and if untreated this results in failure. Thrombosis results from the combination of impaired blood flow, endothelial and vessel wall injury and a propensity towards pro-coagulative states, either intrinsic or aggravated by dialysis or dehydration. The treatment of access thrombosis relies on removal of the clot (thrombectomy) and treatment of the underlying problem. In most cases this is stenosis secondary to neointimal hyperplasia which can occur early (failure to mature) or later...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28707187/imaging-in-vascular-access
#14
Eoin A Murphy, Rose A Ross, Robert G Jones, Stephen J Gandy, Nicolas Aristokleous, Marco Salsano, Jonathan R Weir-McCall, Shona Matthew, John Graeme Houston
This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is the most commonly used modality in VA because it is cheaper (relative to other modalities), accessible, non-ionising, and does not require the use of contrast agents...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28695442/fistula-first-initiative-historical-impact-on-vascular-access-practice-patterns-and-influence-on-future-vascular-access-care
#15
Timmy Lee
The vascular access is the lifeline for the hemodialysis patient. In the United States, the Fistula First Breakthrough Initiative (FFBI) has been influential in improving use of arteriovenous fistulas (AVF) in prevalent hemodialysis patients. Currently, prevalent AVF rates are near the goal of 66% set forth by the original FFBI. However, central venous catheter (CVC) rates remain very high in the United States in patients initiating hemodialysis, nearly exceeding 80%. A new direction of the of the FFBI has focused on strategies to reduce CVC use, and subsequently the FFBI has now been renamed the "Fistula First-Catheter Last Initiative"...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28664239/blood-flow-in-idealized-vascular-access-for-hemodialysis-a-review-of-computational-studies
#16
Bogdan Ene-Iordache, Andrea Remuzzi
Although our understanding of the failure mechanism of vascular access for hemodialysis has increased substantially, this knowledge has not translated into successful therapies. Despite advances in technology, it is recognized that vascular access is difficult to maintain, due to complications such as intimal hyperplasia. Computational studies have been used to estimate hemodynamic changes induced by vascular access creation. Due to the heterogeneity of patient-specific geometries, and difficulties with obtaining reliable models of access vessels, idealized models were often employed...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28623503/investigating-the-suitability-of-carbon-nanotube-reinforced-polymer-in-transcatheter-valve-applications
#17
Monica M Rozeik, David J Wheatley, Terence Gourlay
The current delivery size of transcatheter aortic valves, limited by the thickness of their pericardial leaflets, correlates with a high prevalence of major vascular complications. Polyurethane valves can be developed to a fraction of the thickness of pericardial valves through the addition of carbon nanotubes to reinforce their leaflets. This study investigates the suitability of a novel carbon nanotube reinforced leaflet to reduce the delivery profile of transcatheter aortic valves. Carbon nanotube polyurethane composites were developed with thicknesses of 50 μm and their mechanical properties were determined in relation to various environmental effects...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28608325/pulsatile-flow-leads-to-intimal-flap-motion-and-flow-reversal-in-an-in-vitro-model-of-type-b-aortic-dissection
#18
Joav Birjiniuk, Lucas H Timmins, Mark Young, Bradley G Leshnower, John N Oshinski, David N Ku, Ravi K Veeraswamy
Understanding of the hemodynamics of Type B aortic dissection may improve outcomes by informing upon patient selection, device design, and deployment strategies. This project characterized changes to aortic hemodynamics as the result of dissection. We hypothesized that dissection would lead to elevated flow reversal and disrupted pulsatile flow patterns in the aorta that can be detected and quantified by non-invasive magnetic resonance imaging. Flexible, anatomic models of both normal aorta and dissected aorta, with a mobile intimal flap containing entry and exit tears, were perfused with a physiologic pulsatile waveform...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28597231/development-of-an-in-vitro-piv-setup-for-preliminary-investigation-of-the-effects-of-aortic-compliance-on-flow-patterns-and-hemodynamics
#19
Martin Büsen, Christian Arenz, Michael Neidlin, Sam Liao, Thomas Schmitz-Rode, Ulrich Steinseifer, Simon J Sonntag
The aorta with its compliance plays a major role in hemodynamics as it saves a portion of ejected blood during systole which is then released in diastole. The aortic compliance decreases with increasing age, which is related to several cardiovascular imparities and diseases. Changes in flow patterns and pressure curves, due to varying aortic compliance, are difficult to investigate in vivo. As a result, the aim of the present work was to develop an in vitro setup enabling standardized investigations on the effect of compliance changes on flow patterns and pressure curves...
September 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28567580/review-of-experimental-modelling-in-vascular-access-for-hemodialysis
#20
REVIEW
S Drost, N Alam, J G Houston, D Newport
This paper reviews applications of experimental modelling in vascular access for hemodialysis. Different techniques that are used in in-vitro experiments are bulk pressure and flow rate measurements, Laser Doppler Velocimetry and Vector Doppler Ultrasound point velocity measurements, and whole-field measurements such as Particle Image Velocimetry, Ultrasound Imaging Velocimetry, Colour Doppler Ultrasound, and Planar Laser Induced Fluorescence. Of these methods, the ultrasound techniques can also be used in-vivo, to provide realistic boundary conditions to in-vitro experiments or numerical simulations...
September 2017: Cardiovascular Engineering and Technology
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