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    220 results match your criteria Cardiovascular engineering and technology[Journal]

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    Effect of Pneumatic Tubing System Transport on Platelet Apheresis Units.
    Cardiovasc Eng Technol 2018 May 21. Epub 2018 May 21.
    Division of Trauma, Critical Care and Acute Care Surgery, Department of Surgery, Oregon Health & Science University, Portland, OR, USA.
    Platelet apheresis units are transfused into patients to mitigate or prevent bleeding. In a hospital, platelet apheresis units are transported from the transfusion service to the healthcare teams via two methods: a pneumatic tubing system (PTS) or ambulatory transport. Whether PTS transport affects the activity and utility of platelet apheresis units is unclear. Read More

    Biomechanical Impact of Wrong Positioning of a Dedicated Stent for Coronary Bifurcations: A Virtual Bench Testing Study.
    Cardiovasc Eng Technol 2018 May 17. Epub 2018 May 17.
    Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy.
    The treatment of coronary bifurcations is challenging for interventional cardiologists. The Tryton stent (Tryton Medical, Inc., USA) is one of the few devices specifically designed for coronary bifurcations that underwent large clinical trials. Read More

    The Roles of Matrix Stiffness and ß-Catenin Signaling in Endothelial-to-Mesenchymal Transition of Aortic Valve Endothelial Cells.
    Cardiovasc Eng Technol 2018 May 14. Epub 2018 May 14.
    Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, 661 University Avenue, Toronto, ON, M5G 1M1, Canada.
    Valve stiffening is a hallmark of aortic valve stenosis caused by excess extracellular matrix accumulation by myofibroblasts. We aimed to elucidate whether matrix stiffness regulates endothelial-to-mesenchymal transition (EndMT) of adult valvular endothelial cells (VECs) to myofibroblasts as a mechanism to further promote valve fibrosis. In addition, we specifically examined the role of the Wnt/β-catenin signaling pathway in the development of myofibroblasts during EndMT, as Wnt/β-catenin signaling has been implicated in EndMT during heart development, is reactivated in valve disease, and is required for mechanically-regulated myofibrogenesis of valve interstitial cells. Read More

    Parametric Imaging for the Assessment of Cardiac Motion: A Review.
    Cardiovasc Eng Technol 2018 May 14. Epub 2018 May 14.
    Laboratory of Biophysics and Medical Technology, Higher Institute of Medical Technologies of Tunis, University of Tunis El Manar, 1006, Tunis, Tunisia.
    The assessment of wall motion abnormalities such as hypokinesia or dyskinesia and the identification of their extent as well as their degree of severity allow an accurate evaluation of several ischemic heart diseases and an early diagnosis of heart failure. These dysfunctions are usually revealed by a drop of contraction indicating a regional hypokinesia or a total absence of the wall motion in case of akinesia. The discrimination between these contraction abnormalities plays also a significant role in the therapeutic decision through the differentiation between the infarcted zones, which have lost their contractile function, and the stunned areas that still retain viable myocardial tissues. Read More

    Modeling Right Ventricle Failure After Continuous Flow Left Ventricular Assist Device: A Biventricular Finite-Element and Lumped-Parameter Analysis.
    Cardiovasc Eng Technol 2018 Apr 26. Epub 2018 Apr 26.
    Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS-ISMETT, Palermo, Italy.
    The risk of right ventricle (RV) failure remains a major contraindication for continuous-flow left ventricular assist device (CF-LVAD) implantation in patients with heart failure. It is therefore critical to identify the patients who will benefit from early intervention to avoid adverse outcomes. We sought to advance the computational modeling description of the mechanisms underlying RV failure in LVAD-supported patients. Read More

    Fabrication and Testing of Electrospun Polyurethane Blended with Chitosan Nanoparticles for Vascular Graft Applications.
    Cardiovasc Eng Technol 2018 Apr 26. Epub 2018 Apr 26.
    Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
    In this study, a small vascular graft based on polyurethane (PU) blended with chitosan (Ch) nanoparticles was fabricated using electrospinning technique. Initially, the chitosan nanoparticles were synthesized using ionic gelation method. UV-Vis spectrophotometer confirmed the presence of synthesized Ch nanoparticles by exhibiting absorption peak at 288 nm and the Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the existence of the chitosan. Read More

    Computational Fluid Dynamics Assessment Associated with Transcatheter Heart Valve Prostheses: A Position Paper of the ISO Working Group.
    Cardiovasc Eng Technol 2018 Apr 19. Epub 2018 Apr 19.
    Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA.
    The governing international standard for the development of prosthetic heart valves is International Organization for Standardization (ISO) 5840. This standard requires the assessment of the thrombus potential of transcatheter heart valve substitutes using an integrated thrombus evaluation. Besides experimental flow field assessment and ex vivo flow testing, computational fluid dynamics is a critical component of this integrated approach. Read More

    Realistic Vascular Replicator for TAVR Procedures.
    Cardiovasc Eng Technol 2018 Apr 13. Epub 2018 Apr 13.
    Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, 11794-8151, USA.
    Transcatheter aortic valve replacement (TAVR) is an over-the-wire procedure for treatment of severe aortic stenosis (AS). TAVR valves are conventionally tested using simplified left heart simulators (LHS). While those provide baseline performance reliably, their aortic root geometries are far from the anatomical in situ configuration, often overestimating the valves' performance. Read More

    Cardiogoniometry Compared to Fractional Flow Reserve at Identifying Physiologically Significant Coronary Stenosis: The CARDIOFLOW Study.
    Cardiovasc Eng Technol 2018 Apr 12. Epub 2018 Apr 12.
    Department of Academic Cardiology, University of Hull, Castle Hill Hospital, Daisy Building, Castle Road, Cottingham, HU16 5JQ, UK.
    Cardiogoniometry (CGM) is method of 3-dimensional electrocardiographic assessment which has been shown to identify patients with angiographically defined, stable coronary artery disease (CAD). However, angiographic evidence of CAD, does not always correlate to physiologically significant disease. The aim of our study was to assess the ability of CGM to detect physiologically significant coronary stenosis defined by fractional flow reserve (FFR). Read More

    Aiding the Detection of QRS Complex in ECG Signals by Detecting S Peaks Independently.
    Cardiovasc Eng Technol 2018 Mar 30. Epub 2018 Mar 30.
    CARE, IIT Delhi, New Delhi, India.
    In this paper, a novel algorithm for the accurate detection of QRS complex by combining the independent detection of R and S peaks, using fusion algorithm is proposed. R peak detection has been extensively studied and is being used to detect the QRS complex. Whereas, S peaks, which is also part of QRS complex can be independently detected to aid the detection of QRS complex. Read More

    The Mechanical Characterisation of Bovine Embolus Analogues Under Various Loading Conditions.
    Cardiovasc Eng Technol 2018 Mar 27. Epub 2018 Mar 27.
    GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland.
    Embolus Analogues (EAs) can provide understanding of the mechanical characteristics of blood clots of cardiac origin. Bovine EAs (n = 29) were fabricated with varying concentrations of thrombin (0-20 NIHU/ml blood). Histological staining confirmed that EA composition compared sufficiently with human samples reported in literature. Read More

    A Comparison of Five Algorithms for Fetal Magnetocardiography Signal Extraction.
    Cardiovasc Eng Technol 2018 Mar 26. Epub 2018 Mar 26.
    Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, 4301 West Markham St., #518, Little Rock, AR, 72205, USA.
    Fetal magnetocardiography (fMCG) provides accurate and reliable measurements of electrophysiological events in the fetal heart and is capable of studying fetuses with congenital heart diseases. A variety of techniques exist to extract the fMCG signal with the demand for non-invasively obtained fetal cardiac information. To the best of our knowledge, there is no comparative study published in the field as to how the various extraction algorithms perform. Read More

    Three-Dimensional Strain Measurements of a Tubular Elastic Model Using Tomographic Particle Image Velocimetry.
    Cardiovasc Eng Technol 2018 Mar 20. Epub 2018 Mar 20.
    Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
    The evaluation of strain induced in a blood vessel owing to contact with a medical device is of significance to examine the causes leading to vascular injury and rupture. The development of a method to assess strain in largely deformed elastic materials is expected. This study's scope was to measure strain in deformed tubular elastic mock vessels using tomographic particle image velocimetry (tomo-PIV), and to show the applicability of this measurement method by comparing the results with data derived from a finite element analysis (FEA). Read More

    Efficient Computational Modeling of Human Ventricular Activation and Its Electrocardiographic Representation: A Sensitivity Study.
    Cardiovasc Eng Technol 2018 Mar 16. Epub 2018 Mar 16.
    Lawrence Livermore National Laboratory, 7000 East Avenue L-126, Livermore, CA, 94550, USA.
    Patient-specific models of the ventricular myocardium, combined with the computational power to run rapid simulations, are approaching the level where they could be used for personalized cardiovascular medicine. A major remaining challenge is determining model parameters from available patient data, especially for models of the Purkinje-myocardial junctions (PMJs): the sites of initial ventricular electrical activation. There are no non-invasive methods for localizing PMJs in patients, and the relationship between the standard clinical ECG and PMJ model parameters is underexplored. Read More

    Experimental Assessment of Flow Fields Associated with Heart Valve Prostheses Using Particle Image Velocimetry (PIV): Recommendations for Best Practices.
    Cardiovasc Eng Technol 2018 Mar 12. Epub 2018 Mar 12.
    Abbott Laboratories, Chicago, IL, USA.
    Experimental flow field characterization is a critical component of the assessment of the hemolytic and thrombogenic potential of heart valve substitutes, thus it is important to identify best practices for these experimental techniques. This paper presents a brief review of commonly used flow assessment techniques such as Particle image velocimetry (PIV), Laser doppler velocimetry, and Phase contrast magnetic resonance imaging and a comparison of these methodologies. In particular, recommendations for setting up planar PIV experiments such as recommended imaging instrumentation, acquisition and data processing are discussed in the context of heart valve flows. Read More

    Effect of Interstitial Fluid Flow on Drug-Coated Balloon Delivery in a Patient-Specific Arterial Vessel with Heterogeneous Tissue Composition: A Simulation Study.
    Cardiovasc Eng Technol 2018 Mar 5. Epub 2018 Mar 5.
    Department of Mathematics, Visva-Bharati University, Santiniketan, WB, 731 235, India.
    Angioplasty with drug-coated balloons (DCBs) using excipients as drug carriers is emerging as a potentially viable strategy demonstrating clinical efficacy and proposing additional compliance for the treatment of obstructive vascular diseases. An attempt is made to develop an improved computational model where attention has been paid to the effect of interstitial flow, that is, plasma convection and internalization of bound drug. The present model is capable of capturing the phenomena of the transport of free drug and its retention, and also the internalization of drug in the process of endocytosis to atherosclerotic vessel of heterogeneous tissue composition comprising of healthy tissue, as well as regions of fibrous cap, fibro-fatty, calcified and necrotic core lesions. Read More

    Coating and Pharmacokinetic Evaluation of Air Spray Coated Drug Coated Balloons.
    Cardiovasc Eng Technol 2018 Mar 1. Epub 2018 Mar 1.
    Mechanical Engineering Department, University of South Alabama, Mobile, AL, 36688, USA.
    Drug coated balloons (DCB) are becoming the standard-care treatment for peripheral arterial disease (PAD). DCB use excipients to transfer and retain anti-proliferative drugs, such as paclitaxel. Excipients thus play a vital role in the design and function of DCB, however methods to coat balloons with excipients and anti-proliferative drugs remain unknown. Read More

    Pressure and Flow Rate Changes During Contrast Injections in Cerebral Angiography: Correlation to Reflux Length.
    Cardiovasc Eng Technol 2018 Mar 1. Epub 2018 Mar 1.
    Department of Neurological Surgery, Stony Brook University, HSC T-12, Rm 080, Stony Brook, NY, 11794-8122, USA.
    Cerebral angiography involves the antegrade injection of contrast media through a catheter into the vasculature to visualize the region of interest under X-ray imaging. Depending on the injection and blood flow parameters, the bolus of contrast can propagate in the upstream direction and proximal to the catheter tip, at which point contrast is said to have refluxed. In this in vitro study, we investigate the relationship of fundamental hemodynamic variables to this phenomenon. Read More

    Mechanical Properties and Composition of the Basal Leaflet-Annulus Region of the Tricuspid Valve.
    Cardiovasc Eng Technol 2018 Feb 26. Epub 2018 Feb 26.
    Department of Mechanical Engineering, Texas Tech University, 2703 7th street, PO Box 41021, Lubbock, TX, 79409-1021, USA.
    The Tricuspid valve (TV) annulus is a transition structure from the leaflets to the myocardium, with 3 different annulus segments corresponding to the TV leaflets, which includes both basal leaflets and bordering myocardium. The objective of this study was to understand TV annulus mechanical properties and correlate it to the biological composition. The uniaxial testing of the annulus segments from ten porcine TVs was performed to measure Young's modulus (E) and extensibility (ε). Read More

    Computational Investigation of a Self-Powered Fontan Circulation.
    Cardiovasc Eng Technol 2018 Feb 20. Epub 2018 Feb 20.
    College of Medicine, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, USA.
    Children born with anatomic or functional "single ventricle" must progress through two or more major operations to sustain life. This management sequence culminates in the total cavopulmonary connection, or "Fontan" operation. A consequence of the "Fontan circulation", however, is elevated central venous pressure and inadequate ventricular preload, which contribute to continued morbidity. Read More

    Numerical Investigation of the Effect of Additional Pulmonary Blood Flow on Patient-Specific Bilateral Bidirectional Glenn Hemodynamics.
    Cardiovasc Eng Technol 2018 Jan 22. Epub 2018 Jan 22.
    Department of Mechanics and Engineering Science, Fudan University, No. 220, Handan Road, Shanghai, China.
    The effect of additional pulmonary blood flow (APBF) on the hemodynamics of bilateral bidirectional Glenn (BBDG) connection was marginally discussed in previous studies. This study assessed this effect using patient-specific numerical simulation. A 15-year-old female patient who underwent BBDG was enrolled in this study. Read More

    Quantifying Diastolic Function: From E-Waves as Triangles to Physiologic Contours via the 'Geometric Method'.
    Cardiovasc Eng Technol 2018 Mar 16;9(1):105-119. Epub 2018 Jan 16.
    Cardiovascular Biophysics Laboratory, Cardiovascular Division, Washington University School of Medicine, 660 South Euclid Ave, Box 8086, St. Louis, MO, 63110, USA.
    Conventional echocardiographic diastolic function (DF) assessment approximates transmitral flow velocity contours (Doppler E-waves) as triangles, with peak (E), acceleration time (AT), and deceleration time (DT) as indexes. These metrics have limited value because they are unable to characterize the underlying physiology. The parametrized diastolic filling (PDF) formalism provides a physiologic, kinematic mechanism based characterization of DF by extracting chamber stiffness (k), relaxation (c), and load (x ) from E-wave contours. Read More

    In Vitro Validation of a Numerical Simulation of Leaflet Kinematics in a Polymeric Aortic Valve Under Physiological Conditions.
    Cardiovasc Eng Technol 2018 Mar 10;9(1):42-52. Epub 2018 Jan 10.
    Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia.
    This paper describes a computational method to simulate the non-linear structural deformation of a polymeric aortic valve under physiological conditions. Arbitrary Lagrangian-Eulerian method is incorporated in the fluid-structure interaction simulation, and then validated by comparing the predicted kinematics of the valve's leaflets to in vitro measurements on a custom-made polymeric aortic valve. The predicted kinematics of the valve's leaflets was in good agreement with the experimental results with a maximum error of 15% in a single cardiac cycle. Read More

    Computational Analysis of the Utilisation of the Shape Memory Effect and Balloon Expansion in Fully Polymeric Stent Deployment.
    Cardiovasc Eng Technol 2018 Mar 14;9(1):60-72. Epub 2017 Dec 14.
    Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, NUI Galway, Galway, Ireland.
    The desire to overcome the limitations of cardiovascular metal stents is driven by the global clinical need to improve patient outcomes. The opportunity for fully polymeric stents made from materials like Poly-L-lactide Acid (PLLA) is significant. Unfortunately, this potential has not been fully realised due to pressing concerns regarding the radial strength and recoil associated with material stiffness and recoverability. Read More

    Fabrication and Characterization of Electrospun Bi-Hybrid PU/PET Scaffolds for Small-Diameter Vascular Grafts Applications.
    Cardiovasc Eng Technol 2018 Mar 1;9(1):73-83. Epub 2017 Dec 1.
    Chemical Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran.
    In spite of advances have been made during the past decades, the problems associated with small-diameter vascular grafts, including low patency and compliance mismatch and in consequence of that thrombosis, aneurysm and intimal hyperplasia are still challenges. To address these problems, net polyurethane (PU) and poly (ethylene terephthalate) (PET) polymers and hybrid PU/PET were electrospun to create three different types of small-diameter vascular scaffolds due to their unique physicochemical characteristics: PU, PET, and novel hybrid PU/PET scaffolds. The results show that the PU and PET composite can improve the mechanical properties of the tissue-engineered vascular scaffolds in the range of the native vessels where the non-cytotoxicity characteristic of these well-known polymers is still immutable. Read More

    Novel Direct Annuloplasty Fastener System for Minimally Invasive Mitral Valve Repair.
    Cardiovasc Eng Technol 2018 Mar 22;9(1):53-59. Epub 2017 Nov 22.
    Cardiothoracic Surgery Research Program, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
    The development of less invasive approaches for mitral valve repair remains an important objective, particularly in patients with multiple comorbidities. We describe a novel method to affix a mitral valve annuloplasty ring in a minimally invasive manner. A delivery apparatus for an annuloplasty fastener system was designed. Read More

    High-Fat, High-Sugar Diet-Induced Subendothelial Matrix Stiffening is Mitigated by Exercise.
    Cardiovasc Eng Technol 2018 Mar 20;9(1):84-93. Epub 2017 Nov 20.
    Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, 14853, USA.
    Consumption of a high-fat, high-sugar diet and sedentary lifestyle are correlated with bulk arterial stiffening. While measurements of bulk arterial stiffening are used to assess cardiovascular health clinically, they cannot account for changes to the tissue occurring on the cellular scale. The compliance of the subendothelial matrix in the intima mediates vascular permeability, an initiating step in atherosclerosis. Read More

    16-Channel Flexible System to Measure Electrophysiological Properties of Bioengineered Hearts.
    Cardiovasc Eng Technol 2018 Mar 17;9(1):94-104. Epub 2017 Nov 17.
    Biomedical Engineering Department, University of Houston, Houston, TX, 77204, USA.
    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. Read More

    The Impact of Heat Treatment on Porcine Heart Valve Leaflets.
    Cardiovasc Eng Technol 2018 Mar 13;9(1):32-41. Epub 2017 Nov 13.
    Department of Bioengineering, Clemson-MUSC Bioengineering Program, Clemson University, 173 Ashley Avenue, MSC 508, Charleston, SC, 29425, USA.
    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. Read More

    Development of an Experimental and Digital Cardiovascular Arterial Model for Transient Hemodynamic and Postural Change Studies: "A Preliminary Framework Analysis".
    Cardiovasc Eng Technol 2018 Mar 9;9(1):1-31. Epub 2017 Nov 9.
    North Carolina Agricultural and Technical State University, 1601 East Market Street, Greensboro, NC, 27411, USA.
    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. Read More

    Predicting the Dimensions of an Intracardiac Partial-Assist Pump for Percutaneous Delivery by Analytical and Numerical Methods.
    Cardiovasc Eng Technol 2017 Dec 22;8(4):453-464. Epub 2017 Sep 22.
    Center for Technology and Innovation, Texas Heart Institute, 6770 Bertner Ave, MC 1-268, Houston, TX, 77030, USA.
    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). Read More

    A Patient-Specific Three-Dimensional Hemodynamic Model of the Circle of Willis.
    Cardiovasc Eng Technol 2017 Dec 14;8(4):495-504. Epub 2017 Sep 14.
    Department of Mechanical Engineering, K. N. Toosi University of Technology, 15 Pardis St., Tehran, 1999143344, Iran.
    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. Read More

    Anatomical and Optical Properties of Atrial Tissue: Search for a Suitable Animal Model.
    Cardiovasc Eng Technol 2017 Dec 7;8(4):505-514. Epub 2017 Sep 7.
    Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, 2300 Eye Street NW, Washington, DC, 20052, USA.
    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. Read More

    Experimental Study of Right Ventricular Hemodynamics After Tricuspid Valve Replacement Therapies to Treat Tricuspid Regurgitation.
    Cardiovasc Eng Technol 2017 Dec 29;8(4):401-418. Epub 2017 Aug 29.
    Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
    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. Read More

    Regenerative Stem Cell Therapy Optimization via Tissue Engineering in Heart Failure with Reduced Ejection Fraction.
    Cardiovasc Eng Technol 2017 Dec 28;8(4):515-526. Epub 2017 Aug 28.
    St. Francis Hospital - The Heart Center®, Center for Advanced Cardiac Therapeutics, 100 Port Washington Blvd., Roslyn, NY, 11576-1348, USA.
    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. Read More

    Simulation of Left Ventricular Dynamics Using a Low-Order Mathematical Model.
    Cardiovasc Eng Technol 2017 Dec 15;8(4):480-494. Epub 2017 Aug 15.
    Program in Applied Mathematics, University of Arizona, Tucson, AZ, 85724, USA.
    The eventual goal of this study is to develop methods for estimating dynamic stresses in the left ventricle (LV) that could be used on-line in clinical settings, based on routinely available measurements. Toward this goal, a low-order theoretical model is presented, in which LV shape is represented using a small number of parameters, allowing rapid computational simulations of LV dynamics. The LV is represented as a thick-walled prolate spheroid containing helical muscle fibers with nonlinear passive and time-dependent active contractile properties. Read More

    Biological and Physical Factors Involved in the Maturation of Arteriovenous Fistula for Hemodialysis.
    Cardiovasc Eng Technol 2017 Sep 27;8(3):273-279. Epub 2017 Jul 27.
    Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Ranica, BG, Italy.
    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. Read More

    The Effect of Arterial Curvature on Blood Flow in Arterio-Venous Fistulae: Realistic Geometries and Pulsatile Flow.
    Cardiovasc Eng Technol 2017 Sep 26;8(3):313-329. Epub 2017 Jul 26.
    Department of Aeronautics, Imperial College London, South Kensington, London, SW7 2AZ, UK.
    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. Read More

    Modeling Left Ventricular Blood Flow Using Smoothed Particle Hydrodynamics.
    Cardiovasc Eng Technol 2017 Dec 25;8(4):465-479. Epub 2017 Jul 25.
    The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
    This study aims to investigate the capability of smoothed particle hydrodynamics (SPH), a fully Lagrangian mesh-free method, to simulate the bulk blood flow dynamics in two realistic left ventricular (LV) models. Three dimensional geometries and motion of the LV, proximal left atrium and aortic root are extracted from cardiac magnetic resonance imaging and multi-slice computed tomography imaging data. SPH simulation results are analyzed and compared with those obtained using a traditional finite volume-based numerical method, and to in vivo phase contrast magnetic resonance imaging and echocardiography data, in terms of the large-scale blood flow phenomena usually clinically measured. Read More

    Towards the Identification of Hemodynamic Parameters Involved in Arteriovenous Fistula Maturation and Failure: A Review.
    Cardiovasc Eng Technol 2017 Sep 25;8(3):342-356. Epub 2017 Jul 25.
    Centre for Applied Biomedical Engineering Research, Health Research Institute, Bernal Institute, School of Engineering, University of Limerick, Limerick, Ireland.
    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. Read More

    Maintaining Patency of Vascular Access for Haemodialysis.
    Cardiovasc Eng Technol 2017 Sep 18;8(3):240-243. Epub 2017 Jul 18.
    Department of Radiology, University Hospital Birmingham, Birmingham, UK.
    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. Read More

    Hemodynamic Benefits of Counterpulsation, Implantable, Percutaneous, and Intraaortic Rotary Blood Pumps: An In-Silico and In Vitro Study.
    Cardiovasc Eng Technol 2017 Dec 13;8(4):439-452. Epub 2017 Jul 13.
    Department of Bioengineering, Cardiovascular Innovation Institute, University of Louisville, Louisville, KY, USA.
    Mechanical circulatory support (MCS) devices have become a standard therapy for heart failure (HF) patients. MCS device designs may differ by level of support, inflow and/or outflow cannulation sites, and mechanism(s) of cardiac unloading and blood flow delivery. Investigation and direct comparison of hemodynamic parameters that help characterize performance of MCS devices has been limited. Read More

    Imaging in Vascular Access.
    Cardiovasc Eng Technol 2017 Sep 13;8(3):255-272. Epub 2017 Jul 13.
    Metabolic and Clinical Medicine, College of Medicine, Ninewells Hospital, University of Dundee, Dundee, DD1 9SY, UK.
    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. Read More

    3D Experimental and Computational Analysis of Eccentric Mitral Regurgitant Jets in a Mock Imaging Heart Chamber.
    Cardiovasc Eng Technol 2017 Dec 10;8(4):419-438. Epub 2017 Jul 10.
    The Methodist Hospital Houston, 6550 Fannin Suite 1901, Houston, TX, 77030, USA.
    Mitral valve regurgitation (MR) is a disorder of the heart in which the mitral valve does not close properly. This causes an abnormal leaking of blood backwards from the left ventricle into the left atrium during the systolic contractions of the left ventricle. Noninvasive assessment of MR using echocardiography is an ongoing challenge. Read More

    Fistula First Initiative: Historical Impact on Vascular Access Practice Patterns and Influence on Future Vascular Access Care.
    Cardiovasc Eng Technol 2017 Sep 10;8(3):244-254. Epub 2017 Jul 10.
    Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, 1720 2nd Ave South, Birmingham, AL, 35294-0007, USA.
    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. Read More

    Blood Flow in Idealized Vascular Access for Hemodialysis: A Review of Computational Studies.
    Cardiovasc Eng Technol 2017 Sep 29;8(3):295-312. Epub 2017 Jun 29.
    Laboratory of Biomedical Technologies, Clinical Research Center for Rare Diseases Aldo e Cele Daccò, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi 3, 24020, Ranica, BG, Italy.
    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. Read More

    Arrhythmia Vulnerability in Diabetic Cardiac Tissue is Species-Dependent: Effects of I , Uncoupling, and Connexin Lateralization.
    Cardiovasc Eng Technol 2017 Dec 27;8(4):527-538. Epub 2017 Jun 27.
    Department of Electrical and Computer Engineering, and Centre for Bioengineering Research & Education, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada.
    Amongst the complications of diabetes is arrhythmia, the risk of which depends on multiple factors. This study was designed to investigate several factors, including the effects of ATP-sensitive potassium current, lateralized connexins, and gap junction uncoupling. ATP-sensitive potassium channel (I ) opening is caused by ischemia, which can occur in diabetic or non-diabetic hearts. Read More

    Investigating the Suitability of Carbon Nanotube Reinforced Polymer in Transcatheter Valve Applications.
    Cardiovasc Eng Technol 2017 Sep 16;8(3):357-367. Epub 2017 Jun 16.
    Department of Biomedical Engineering, Wolfson Centre, University of Strathclyde, 106 Rottenrow, Glasgow, G4 0NW, UK.
    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. Read More

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