Search our Database of Scientific Publications and Authors

I’m looking for a

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

    1 OF 4

    Quantifying Diastolic Function: From E-Waves as Triangles to Physiologic Contours via the 'Geometric Method'.
    Cardiovasc Eng Technol 2018 Jan 16. 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 (Epeak), 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 o ) 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 Jan 10. 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 2017 Dec 14. 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 2017 Dec 1. 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 2017 Nov 22. 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 2017 Nov 20. 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 2017 Nov 17. 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 2017 Nov 13. 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 2017 Nov 9. 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 KATP, 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 KATP) 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

    Pulsatile Flow Leads to Intimal Flap Motion and Flow Reversal in an In Vitro Model of Type B Aortic Dissection.
    Cardiovasc Eng Technol 2017 Sep 12;8(3):378-389. Epub 2017 Jun 12.
    Division of Vascular Surgery, Department of Surgery, Medical University of South Carolina, 114 Doughty Street Suite BM 654 MSC 295, Charleston, SC, 29425, USA.
    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. Read More

    Development of an In Vitro PIV Setup for Preliminary Investigation of the Effects of Aortic Compliance on Flow Patterns and Hemodynamics.
    Cardiovasc Eng Technol 2017 Sep 8;8(3):368-377. Epub 2017 Jun 8.
    Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Aachen, Germany.
    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. Read More

    Review of Experimental Modelling in Vascular Access for Hemodialysis.
    Cardiovasc Eng Technol 2017 Sep 31;8(3):330-341. Epub 2017 May 31.
    School of Engineering, Bernal Institute, University of Limerick, Limerick, Ireland.
    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. Read More

    Local Hemodynamic Differences Between Commercially Available Y-Grafts and Traditional Fontan Baffles Under Simulated Exercise Conditions: Implications for Exercise Tolerance.
    Cardiovasc Eng Technol 2017 Sep 30;8(3):390-399. Epub 2017 May 30.
    Division of Cardiology, Department of Pediatrics, Children's Healthcare of Atlanta, Emory University School of Medicine, Philadelphia, PA, USA.
    Fontan completion, resulting in a total cavopulmonary connection (TCPC), is accomplished using a lateral tunnel (LT), extracardiac conduit (ECC), or recently a bifurcated Y-graft. The local energetic differences between these graft types have not been substantially analyzed under exercise conditions. The present study evaluates the energetic performance of Y-grafts under simulated exercise conditions, compares their performance to the previous LT/ECC Fontan options, and discusses implications for exercise tolerance and hemodynamic predictability. Read More

    A Review of the Hemodynamic Factors Believed to Contribute to Vascular Access Dysfunction.
    Cardiovasc Eng Technol 2017 Sep 19;8(3):280-294. Epub 2017 May 19.
    Centre for Applied Biomedical Engineering Research, Health Research Institute, Bernal Institute, School of Engineering, University of Limerick, Limerick, Ireland.
    A vascular access (VA) is used to facilitate hemodialysis in patients that suffer from end-stage renal disease. However, they suffer from high failure rates due to non-maturation and venous stenosis, with intimal hyperplasia (IH) the underlying cause of both conditions. Abnormal hemodynamic profiles, which arise following VA creation, are believed to lead to the development of IH. Read More

    Endovascular Crossing of Chronic Total Occlusions Using an Impulse: An Explorative Design Study.
    Cardiovasc Eng Technol 2017 Jun 17;8(2):145-163. Epub 2017 May 17.
    Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands.
    In this study we investigated whether exerting an impulse on a Chronic Total Occlusion (CTO) improves the success rate of CTO crossing as compared to the currently used method of statically pushing the guidewire against the CTO. A prototype (Ø2 mm) was developed that generates translational momentum using a spring-loaded indenter and converts it to an impulse during impact. Mechanical performance was evaluated by measuring the peak force and momentum for different spring compressions and strike distances in air and blood-mimicking fluid. Read More

    A Novel Idea to Improve Cardiac Output of Mechanical Circulatory Support Devices by Optimizing Kinetic Energy Transfer Available in Forward Moving Aortic Blood Flow.
    Cardiovasc Eng Technol 2017 Jun 16;8(2):131-144. Epub 2017 May 16.
    Department of Bioengineering and CT Surgery, University of Louisville, Louisville, KY, USA.
    Mechanical circulatory support devices (MCSDs) have gained widespread clinical acceptance as an effective heart failure (HF) therapy. The concept of harnessing the kinetic energy (KE) available in the forward aortic flow (AOF) is proposed as a novel control strategy to further increase the cardiac output (CO) provided by MCSDs. A complete mathematical development of the proposed theory and its application to an example MCSDs (two-segment extra-aortic cuff) are presented. Read More

    Multiphysics Modeling of the Atrial Systole under Standard Ablation Strategies.
    Cardiovasc Eng Technol 2017 Jun 16;8(2):205-218. Epub 2017 May 16.
    Institute for Computational Mechanics, Technical University of Munich, Boltzmannstr. 15, 85748, Garching b. München, Germany.
    The aim of this study was to develop a computational framework to compare the impact of standard ablation concepts on the mechanical performance of the atria, since different line combinations cannot be applied in practice to the same patient. For this purpuse, we coupled electro-mechano-hemodynamic mathematical models based on biophysical principles and simulate the contractile performance of the atria. We computed systolic pressures and volumes in two patient-specific atrial geometries (one of normal size and one hypertrophied) with various ablation concepts. Read More

    Prediction of Thrombus Growth: Effect of Stenosis and Reynolds Number.
    Cardiovasc Eng Technol 2017 Jun 3;8(2):164-181. Epub 2017 May 3.
    Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
    Shear stresses play a major role in platelet-substrate interactions and thrombus formation and growth in blood flow, where under both pathological and physiological conditions platelet adhesion and accumulation occur. In this study, a shear-dependent continuum model for platelet activation, adhesion and aggregation is presented. The model was first verified under three different shear conditions and at two heparin levels. Read More

    A Novel Mean-Value Model of the Cardiovascular System Including a Left Ventricular Assist Device.
    Cardiovasc Eng Technol 2017 Jun 2;8(2):120-130. Epub 2017 May 2.
    Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
    Time-varying elastance models (TVEMs) are often used for simulation studies of the cardiovascular system with a left ventricular assist device (LVAD). Because these models are computationally expensive, they cannot be used for long-term simulation studies. In addition, their equilibria are periodic solutions, which prevent the extraction of a linear time-invariant model that could be used e. Read More

    Tetralogy of Fallot Surgical Repair: Shunt Configurations, Ductus Arteriosus and the Circle of Willis.
    Cardiovasc Eng Technol 2017 Jun 5;8(2):107-119. Epub 2017 Apr 5.
    Department of Mechanical Engineering, Koç University, Rumeli Feneri Kampüsü, Sarıyer, Istanbul, Turkey.
    In this study, hemodynamic performance of three novel shunt configurations that are considered for the surgical repair of tetralogy of Fallot (TOF) disease are investigated in detail. Clinical experience suggests that the shunt location, connecting angle, and its diameter can influence the post-operative physiology and the neurodevelopment of the neonatal patient. An experimentally validated second order computational fluid dynamics (CFD) solver and a parametric neonatal diseased great artery model that incorporates the ductus arteriosus (DA) and the full patient-specific circle of Willis (CoW) are employed. Read More

    Correlation of Wall Microstructure and Heterogeneous Distributions of Strain in Evolving Murine Abdominal Aortic Aneurysms.
    Cardiovasc Eng Technol 2017 Jun 4;8(2):193-204. Epub 2017 Apr 4.
    Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
    A primary deficiency in predicting the progression and rupture-risk of abdominal aortic aneurysms (AAAs) is an inability to assign patient-specific, heterogeneous biomechanical properties to the remodelling aortic wall. Toward this end, we investigated possible correlations between three quantities having the potential for non-invasive measurement (diameter, wall thickness, and strain) and local wall microstructure within evolving experimental AAAs. AAAs were initiated in male C57BL/6J mice via in situ adventitial application of elastase and allowed to progress for 1-4 weeks. Read More

    Comparison of Blood Viscoelasticity in Pediatric and Adult Cardiac Patients.
    Cardiovasc Eng Technol 2017 Jun 10;8(2):182-192. Epub 2017 Mar 10.
    Cardiovascular Innovation Institute, University of Louisville, Louisville, KY, USA.
    Evidence is accumulating that blood flow patterns in the cardiovascular system and in cardiovascular devices do, in some instances, depend on blood viscoelasticity. Thus, to better understand the challenges to providing circulatory support and surgical therapies for pediatric and adult patients, viscous and elastic components of complex blood viscoelasticity of 31 pediatric patients were compared to those of 29 adult patients with a Vilastic-3 rheometer. A random effects model with categorical age covariates found statistically significant differences between pediatric and adult patients for log viscosity (p = 0. Read More

    Effect of Loss of Heart Rate Variability on T-Wave Heterogeneity and QT Variability in Heart Failure Patients: Implications in Ventricular Arrhythmogenesis.
    Cardiovasc Eng Technol 2017 Jun 3;8(2):219-228. Epub 2017 Mar 3.
    School of Electrical & Electronic Engineering, University of Adelaide, Adelaide, Australia.
    Heart rate variability (HRV) modulates dynamics of ventricular repolarization. A diminishing value of HRV is associated with increased vulnerability to life-threatening ventricular arrhythmias, however the causal relationship is not well-defined. We evaluated if fixed-rate atrial pacing that abolishes the effect of physiological HRV, will alter ventricular repolarization wavefronts and is relevant to ventricular arrhythmogenesis. Read More

    Elevated Serotonin Interacts with Angiotensin-II to Result in Altered Valve Interstitial Cell Contractility and Remodeling.
    Cardiovasc Eng Technol 2017 Feb 28. Epub 2017 Feb 28.
    Department of Biomedical Engineering, University of Arkansas, 122 John A. White Jr. Engineering Hall, Fayetteville, AR, 72701, USA.
    While the valvulopathic effects of serotonin (5HT) and angiotensin-II (Ang-II) individually are known, it was not clear how 5HT and Ang-II might interact, specifically in the context of the mechanobiological responses due to altered valve mechanics potentiated by these molecules. In this context, the hypothesis of this study was that increased serotonin levels would result in accelerated progression toward disease in the presence of angiotensin-II-induced hypertension. C57/BL6 J mice were divided into four groups and subcutaneously implanted with osmotic pumps containing: PBS (control), 5HT (2. Read More

    Computer-Based CPR Simulation Towards Validation of AHA/ERC Guidelines.
    Cardiovasc Eng Technol 2017 Jun 27;8(2):229-235. Epub 2017 Feb 27.
    SRMC & RI, Porur, Chennai, Tamil Nadu, India.
    As per the AHA 2015 and ERC 2015 guidelines for resuscitation, chest compression depth should be between 5 and 6 cm with a rate of 100-120 compressions per minute. Theoretical validation of these guidelines is still elusive. We developed a computer model of the cardiopulmonary resuscitation (CPR) system to validate these guidelines. Read More

    Mechanosensitive microRNA-181b Regulates Aortic Valve Endothelial Matrix Degradation by Targeting TIMP3.
    Cardiovasc Eng Technol 2017 Feb 24. Epub 2017 Feb 24.
    Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA.
    Calcific aortic valve disease (CAVD) is a major cause of morbidity in the aging population, but the underlying mechanisms of its progression remain poorly understood. Aortic valve calcification preferentially occurs on the fibrosa, which is subjected to disturbed flow. The side-specific progression of the disease is characterized by inflammation, calcific lesions, and extracellular matrix (ECM) degradation. Read More

    Vascular Coupling System for End-to-End Anastomosis: An In Vivo Pilot Case Report.
    Cardiovasc Eng Technol 2017 Mar 6;8(1):91-95. Epub 2017 Feb 6.
    Department of Surgery, School of Medicine, University of Utah, 30 N 1900 E, Salt Lake City, UT, 84132, USA.
    This paper presents the latest in vivo findings of a novel vascular coupling system. Vascular anastomosis is a common procedure in reconstructive surgeries and traditional hand suturing is very time consuming. The vascular coupling system described herein was designed to be used on arteries for a rapid and error-free anastomosis. Read More

    Investigation of Stent Implant Mechanics Using Linear Analytical and Computational Approach.
    Cardiovasc Eng Technol 2017 Mar 3;8(1):81-90. Epub 2017 Feb 3.
    Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX, 78249, USA.
    Stent implants are essential in restoring normal blood flow in atherosclerotic arteries. Recent studies have shown high failure rates of stent implants in superficial femoral artery (SFA) as a result of dynamic loading environment imposed on the stent implants by the diseased arterial wall and turbulent blood flow. There are variety of stent designs and materials currently on the market however, there is no clear understanding if specific stent design is suitable with the material that is manufactured from and if this combination can sustain the life-cycle that the stent implants need to undergo once inside the artery. Read More

    Analytical Modeling for Computing Lead Stress in a Novel Epicardial Micropacemaker.
    Cardiovasc Eng Technol 2017 Mar 9;8(1):96-105. Epub 2017 Jan 9.
    Medical Device Development Facility, Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA, 90089, USA.
    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. Read More

    Finite Element Analysis of Patient-Specific Mitral Valve with Mitral Regurgitation.
    Cardiovasc Eng Technol 2017 Mar 9;8(1):3-16. Epub 2017 Jan 9.
    The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206, 387 Technology Circle, Atlanta, GA, 30313-2412, USA.
    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. Read More

    1 OF 4