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Total 28 records

    Thickness as an important parameter in designing vascular grafts

    , Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014 ; Nov , 2014 , p. 40-43 Mohseni, M ; Shamloo, A ; Samani, S. A ; Dodel, M ; Sharif University of Technology
    Abstract
    The main goal of this study is to investigate the role of vascular graft thickness in wall stress gradient in anastomosis region. Atherosclerosis is a common heart disease causes high mortality rates every year. The gold standard treatment of atherosclerosis is replacing with autologous vein extracted from patient's body. Since proper autologous vein is limited, researchers have made efforts to achieve compliance engineered blood vessels. Mechanical stress has great effect on both smooth muscle cells and endothelial cells and it is considered as a stimulus in plaque formation. In this study, we evaluate the role of thickness in wall stress of anastomosis region. For this purpose, two... 

    A simple model of intimal thickening-effects of hypertension

    , Article 2012 19th Iranian Conference of Biomedical Engineering, ICBME 2012 ; 2012 , Pages 276-281 ; 9781467331302 (ISBN) Mirbagheri, S. A ; Saidi, M. S ; Firoozabadi, D ; Sharif University of Technology
    2012
    Abstract
    A vast amount of death in the world has been attributed to atherosclerosis. This disease causes plaque formation and finally lack of blood supply to an organ. The prominent aim of this study is proposing an accurate and simple model to investigate the process of arterial wall thickening. In order to investigate LDL (low density lipoprotein) accumulation in arterial wall which is considered the first stage of atherosclerosis, a four layer model for arterial wall consisting of endothelium, intima, IEL and media is presented. All layers are treated as homogenous porous media. The four-layer arterial wall model is the most powerful and reliable tool for modeling LDL transport within arterial... 

    Thickness as an important parameter in designing vascular grafts

    , Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014, 26 November 2014 through 28 November 2014 ; November , 2014 , Pages 40-43 ; 9781479974177 (ISBN) Mohseni, M ; Shamloo, A ; Samani, S. A ; Dodel, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2014
    Abstract
    The main goal of this study is to investigate the role of vascular graft thickness in wall stress gradient in anastomosis region. Atherosclerosis is a common heart disease causes high mortality rates every year. The gold standard treatment of atherosclerosis is replacing with autologous vein extracted from patient's body. Since proper autologous vein is limited, researchers have made efforts to achieve compliance engineered blood vessels. Mechanical stress has great effect on both smooth muscle cells and endothelial cells and it is considered as a stimulus in plaque formation. In this study, we evaluate the role of thickness in wall stress of anastomosis region. For this purpose, two... 

    , M.Sc. Thesis Sharif University of Technology Kelaretaghi, Naghi (Author) ; Hesaraki, Mahmoud (Supervisor)
    Abstract
    Our problem is to evaluation state and form of a tracer passing through the vessel. Using this method, we can identify the effect of during used in some defected parts of body. This evaluation leads to in solving a Laplace equation with mixed boundary condition. Separating that problem, we reach to a collection of algebraic and linear equations. Solving this system, we approximate coefficients of the solution with a series the existence and uniqueness of and analytic solution has been proved using the Eigen functions finally, using numerical algorithms, we have interpreted the analytical solutions.
     

    Effects of hypertension on Intima-Media Thickness (IMT); application to a human carotid artery

    , Article Scientia Iranica ; Volume 23, Issue 4 , 2016 , Pages 1731-1740 ; 10263098 (ISSN) Mirbagheri, S. A ; Saidi, M. S ; Sohrabi, S ; Firoozabadi, B ; Banazadeh, M. H ; Sharif University of Technology
    Sharif University of Technology 
    Abstract
    A vast number of deaths in the world have been attributed to atherosclerosis. The prominent aim of this study is proposing an accurate and simple model to investigate the process of arterial wall thickening. In order to investigate LDL (Low Density Lipoprotein) accumulation in arterial wall, a four layer model for arterial wall consisting of endothelium, intima, IEL, and media is presented. All layers are treated as homogenous porous media. This model has been solved both numerically and analytically. Obtained accumulated LDL in the intima is used to calculate oxidized LDL flux. Also, the presented model and clinical data are used to prepare the growth model for arterial wall. Furthermore,... 

    Nanotechnology in diagnosis and treatment of coronary artery disease

    , Article Nanomedicine ; Volume 11, Issue 5 , 2016 , Pages 513-530 ; 17435889 (ISSN) Karimi, M ; Zare, H ; Bakhshian Nik, A ; Yazdani, N ; Hamrang, M ; Mohamed, E ; Sahandi Zangabad, P ; Moosavi Basri, S. M ; Bakhtiari, L ; Hamblin, M. R ; Sharif University of Technology
    Future Medicine Ltd 
    Abstract
    Nanotechnology could provide a new complementary approach to treat coronary artery disease (CAD) which is now one of the biggest killers in the Western world. The course of events, which leads to atherosclerosis and CAD, involves many biological factors and cellular disease processes which may be mitigated by therapeutic methods enhanced by nanotechnology. Nanoparticles can provide a variety of delivery systems for cargoes such as drugs and genes that can address many problems within the arteries. In order to improve the performance of current stents, nanotechnology provides different nanomaterial coatings, in addition to controlled-release nanocarriers, to prevent in-stent restenosis.... 

    A multiscale approach for determining the morphology of endothelial cells at a coronary artery

    , Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 33, Issue 12 , 2017 ; 20407939 (ISSN) Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    Abstract
    The morphology of endothelial cells (ECs) may be an indication for determining atheroprone sites. Until now, there has been no clinical imaging technique to visualize the morphology of ECs in the arteries. The present study introduces a computational technique for determining the morphology of ECs. This technique is a multiscale simulation consisting of the artery scale and the cell scale. The artery scale is a fluid-structure interaction simulation. The input for the artery scale is the geometry of the coronary artery, that is, the dynamic curvature of the artery due to the cardiac motion, blood flow, blood pressure, heart rate, and the mechanical properties of the blood and the arterial... 

    Numerical Analysis of Channel Flow over an Elastic Bump, Using Lattice Boltzmann Method- A Biological Application

    , M.Sc. Thesis Sharif University of Technology Rostami Gandomani, Saeed (Author) ; Taeibi Rahni, Mohammad (Supervisor)
    Abstract
    In recent years, lattice Boltzmann method (LBM) has been developed to be used as an alternative and promising computational technique to simulate various flows. It originates from classical statistical physics. The ability to simply solve complex flows, simulating of multiphase and multi-component without need to follow the boundaries of different phases, and the inherent ability of parallel processing are notable features of this approach. On the other hand, finite element method (FEM) is widely used in many practical engineering fields, especially in solid mechanics. In this study, in addition to simulating flow over a rigid body, flow over an elastic body is also simulated with a... 

    Simulation of low density lipoprotein (LDL) permeation into multilayer coronary arterial wall: interactive effects of wall shear stress and fluid-structure interaction in hypertension

    , Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) Roustaei, M ; Nikmaneshi, M. R ; Firoozabadi, B ; Sharif University of Technology
    Abstract
    Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration... 

    Simulation of low density lipoprotein (LDL) permeation into multilayer coronary arterial wall: interactive effects of wall shear stress and fluid-structure interaction in hypertension

    , Article Journal of Biomechanics ; Volume 67 , 2018 , Pages 114-122 ; 00219290 (ISSN) Roustaei, M ; Nikmaneshi, M. R ; Firoozabadi, B ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration... 

    Simulation of Competitive Flow in the Coronary Arteries Bypass

    , M.Sc. Thesis Sharif University of Technology Azimi Nejad, Milad (Author) ; Firoozabadi, Bahar (Supervisor)
    Abstract
    Atherosclerosis is one of the most important factors for mortality and morbidity in the world. Coronary artery bypass graft (CABG) is applied for treatment of this disease which in this surgery, the patient vessels, such as internal thoracic artery and saphenous vein, are harvested and grafted to the coronary arteries. The graft success and its performance in short and long-term are depended on the much factors e.g. the severity of stenosis in the coronary artery. It should be noted that the low level of stenosis in the coronary artery causes the creation of undesirable phenomenon of competitive flow in the grafts after the surgery which this phenomenon has been reported as a cause of graft... 

    Constitutive Modeling and Numerical Simulation of Coronary Arteries Mechanical Behavior in Stenting and Succeeding Growth

    , Ph.D. Dissertation Sharif University of Technology Fereidoonnezhad, Behrooz (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    Abstract
    Cardiovascular diseases are the major cause of death worldwide. Atherosclerosis is one of the major types of cardiovascular diseases in which fibrous and fatty materials, called plaque, build up inside the artery and cause partial or total occlusion of the artery. Intravascular balloon angioplasty with or without stenting is the most common treatment of this disease. In 2010, approximately 954000 stent implantations were performed in the United States. The major issue associated with stenting is reclosure or renarrowing of the transverse section of the artery termed in-stent restenosis (ISR). Unfortunately, nearly one–third of the patients
    who receive stent implantation require further... 

    Multiscale Modeling of Coronary Blood Flow and Effects on Endothelial Cells

    , Ph.D. Dissertation Sharif University of Technology Pakravan, Hossein Ali (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Firoozabadi, Bahar (Co-Advisor)
    Abstract
    Atherosclerosis in coronary arteries is one of the most important topics due to its high prevalence and the importance of these arteries for supplying blood to the heart. The morphology of endothelial cells (ECs) is an independent index for determining the atheroprone sites. The ECs show a regular elongated and aligned configuration to the blood flow, at the atheroprotected regions; on the other hand, at the atheroprone regions, the cells have a polygonal, randomly oriented morphology. The thesis intended to propose a method for coronary artery simulation, which is able to determine the atheroprone sites regarding the ECs morphology. In addition, the attempts were made to investigate the... 

    Stability of Atherosclerotic Arteries Using Fluid-structure Interaction

    , M.Sc. Thesis Sharif University of Technology Manzoori, Amir Hossein (Author) ; Fallah, Famida (Supervisor)
    Abstract
    Tortuosity is an abnormality that may occur in some arteries, such as carotid. It can reduce the blood flow to distal organs, and even in severe cases, causes ischemia and stroke. Tortuosity can be congenital or occurs due to hypertension and reduced axial pre-stretch of artery, in which case called buckling. Since atherosclerotic plaques disrupt the normal pattern of blood flow, and thus make the artery more susceptible to buckling, in this study, the effect of atherosclerotic plaques on arterial stability has been investigated using computational simulation of fluid-structure interaction under pulsatile flow and large deformation. Ideal geometry of normal and atherosclerotic carotid artery... 

    Modeling of Deposition of Low Density Lipoprotein (LDL) in Carotid Artery

    , M.Sc. Thesis Sharif University of Technology Mirbagheri, Amir (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    Abstract
    Atherosclerosis is one of the most important and common causes of death in the world. Atherosclerosis typically affects medium and large arteries in the body and it leads to plaque formation in arterial wall. The first stage of plaque formation has been related to accumulation of low density lipoproteins in arterial wall.
    The purpose of this research is presenting a four-layer model to describe the LDL transport in the arterial wall. The endothelium, intima, internal elastic lamina (IEL) and media are all treated as macroscopically homogeneous porous media and the volume-averaged porous media equations are employed to model various layers. The physiological parameters within the various... 

    Modeling of Blood Flow and Deposition of Low Density Lipoprotein (LDL) in Coronary Arteries

    , M.Sc. Thesis Sharif University of Technology Emami Meybodi, Ali (Author) ; Firoozabadi, Bahar (Supervisor) ; Saidi, Mohammad Said (Co-Advisor)
    Abstract
    In this thesis, hemodynamic parameters of flow and deposition of low density lipoproteins (LDL) on wall of coronary arteries with taking into account their curvature on the heart are studied. At first, numerical solution of the blood flow by assumption of blood as incompressible and Newtonian fluid for steady and pulsatile inlet is done. Then by assuming LDL particles as dilute solute in the blood, LDL transport from artery lumen into arterial wall is studied. LDL accumulation and penetration into the vessel wall cause thickening of the walls and eventually eclipse it and its known as the first stage of atherosclerosis disease. The results show that low shear region occurs on inner wall... 

    Simulation of LDL Permeation into Multilayer Coronary Arterial Wall: Interactive Effects of Wall Shear Stress and Fluid-Structure Interaction in Hypertension

    , M.Sc. Thesis Sharif University of Technology Roustaei, Mehrdad (Author) ; Dehghan Firoozabadi, Bahar (Supervisor)
    Abstract
    Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration... 

    Modeling Flow and Fat Particle Deposition in Coronary Arteries

    , M.Sc. Thesis Sharif University of Technology Biglarian, Mohit (Author) ; Firoozabadi, Bahar (Supervisor) ; Saeedi, Mohammad Saeed (Co-Advisor)
    Abstract
    In this thesis, flow hemodynamic parameters and white blood cell deposition on the 3- D of coronary artries of heart coronary walls are studied. At first, numerical simulation of blood flow and without the presence of white cells is performed. Then, using the Lagrangian approach, white blood cells as solid particles are tracked considering forces such as drag force, weight, buoyancy, Saffman lift force, virtual mass in one way coupling method. this particle representive of white blood cells and play significant role in low density lipoprotein (LDL) deposition.The results show that a low shear region occurs on myocardial wall. maximum flow velocity near the bifurcation towards epicardial wall... 

    Stability of Coronary Arteries Arteriosclerosis Using Fluid-Structure Interaction

    , M.Sc. Thesis Sharif University of Technology Ebrahimi Hasratanloo, Sina (Author) ; Fallah Ragabzadeh, Famida (Supervisor)
    Abstract
    Coronary arteries often experience tortuosity under internal blood pressure and longitude axial twisting. Arterial tortuosity can enhance the stress concentration on the artery walls. Now if the coronary arteries suffer from atherosclerosis (a common disease among adults) the stress concentration on the tortuous artery plaque will be enhanced as well. Increased stress on the plaque may result in plaque rupture and its consequent damages. This study aims to investigate the stress concentration on the plaques and blood flow patterns within the coronary arteries with plaque. Moreover, the plaque growth was predicted taking into account various geometrical parameters including fibrous cap... 

    Primary stenosis progression versus secondary stenosis formation in the left coronary bifurcation: a mechanical point of view

    , Article Biocybernetics and Biomedical Engineering ; Volume 39, Issue 1 , 2019 , Pages 188-198 ; 02085216 (ISSN) Jahromi, R ; Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    Elsevier Sp. z o.o  2019
    Abstract
    Biomechanical forces and hemodynamic factors influence the blood flow and the endothelial cells (ECs) morphology. These factors behave differently beyond the coronary artery stenosis. In the present study, unsteady blood flow in the left coronary artery (LCA) and its atherosclerotic bifurcating vessels, left anterior descending (LAD) and left circumflex (LCX) arteries, were numerically simulated to investigate the risk of plaque length development and secondary plaque formation in the post-stenotic areas. Using fluid–structure interaction (FSI) model, compliance of arterial wall and vessel curvature variations due to cardiac motion were considered. The arteries included plaques at the...