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    2-D Modeling of Blood Flow in Mitral Valve During its Closing and Opening

    , M.Sc. Thesis Sharif University of Technology Jamshidi, Hadi (Author) ; Firoozabadi, Bahar (Supervisor) ; Saeedi, Mohammad Saeed (Co-Supervisor)
    Abstract
    Problems with the mitral valve can make the heart less efficient at pumping blood around the body. Severe problems can lead to heart failure if the valve is not surgically repaired or replaced. A simple approximation of the heart geometry is used and the valve dimensions are based on reported measurements. The primary objective for this study is to design and simulate the opening and closing behavior of the mitral valve using 2D fluid-structure interaction (FSI) model using ADINA software in order to evaluate and investigate the hemodynamic performance and problems of mitral valve, in which the blood is described as a viscous incompressible fluid, and the mitral valve is described as an... 

    Investigation of Modeling and Implementation of Systolic Arrays on Accelerators

    , M.Sc. Thesis Sharif University of Technology Zarei, Parisa (Author) ; Ghodsi, Mohammad (Supervisor)
    Abstract
    The ever-increasing volume of data and calculations has caused a noticeable increase in the importance of computer processing speed. Therefore, topics related to parallel processing as an effective solution in increasing the speed of calculations have been specially investigated and studied. Systolic computing is a powerful approach to parallelize data and perform concurrent computations. Systolic arrays fulfill the goals of the algorithm by directing data flow among different processors and performing minor calculations on them. The slowness and limitations of processors compatible with these arrays, such as FPGAs, have faced many challenges in applying and using their capacities. These... 

    Systolic gaussian normal basis multiplier architectures suitable for high-performance applications

    , Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 23, Issue 9 , 2015 , Pages 1969-1972 ; 10638210 (ISSN) Azarderakhsh, R ; Kermani, M. M ; Bayat Sarmadi, S ; Lee, C. Y ; Sharif University of Technology
    Abstract
    Normal basis multiplication in finite fields is vastly utilized in different applications, including error control coding and the like due to its advantageous characteristics and the fact that squaring of elements can be obtained without hardware complexity. In this brief, we present decomposition algorithms to develop novel systolic structures for digit-level Gaussian normal basis multiplication over GF (2m). The proposed architectures are suitable for high-performance applications, which require fast computations in finite fields with high throughputs. We also present the results of our application-specific integrated circuit synthesis using a 65-nm standard-cell library to benchmark the... 

    Cuff-less high-accuracy calibration-free blood pressure estimation using pulse transit time

    , Article Proceedings - IEEE International Symposium on Circuits and Systems, 24 May 2015 through 27 May 2015 ; Volume 2015-July , 2015 , Pages 1006-1009 ; 02714310 (ISSN) ; 9781479983919 (ISBN) Kachuee, M ; Kiani, M.M ; Mohammadzade, H ; Shabany, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    Recently a few methods have been proposed in the literature for non-invasive cuff-less estimation of systolic and diastolic blood pressures. One of the most prominent methods is to use the Pulse Transit Time (PTT). Although it is proven that PTT has a strong correlation with the systolic and diastolic blood pressures, this relation is highly dependent to each individuals physiological properties. Therefore, it requires per person calibration for accurate and reliable blood pressure estimation from PTT, which is a big drawback. To alleviate this issue, in this paper, a novel method is proposed for accurate and reliable estimation of blood pressure that is calibration-free. This goal is... 

    Robust control of LVAD based on the sub-regional modeling of the heart

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart... 

    Characteristics of early repolarization pattern in the Iranian population

    , Article Iranian Red Crescent Medical Journal ; Volume 19, Issue 3 , 2017 ; 20741804 (ISSN) Mollazadeh, R ; Sehhati, F ; Eslami, M ; Nemati, F ; Monfarednasab, M ; Sefidbakht, S ; Sharif University of Technology
    Kowsar Medical Publishing Company  2017
    Abstract
    Background: The early repolarization pattern (ERP) has been considered a normal variant in electrocardiography (ECG) for a long time. Nevertheless, increasing evidence has demonstrated its association with adverse outcomes. Objectives: The present study aimed to evaluate the prevalence of ERP in the Iranian general population and demonstrate its clinical and ECG correlates. Methods: A cross sectional study, comprising 1424 consecutive healthy adult individuals, was conducted at two university based hospitals in Tehran, Iran in 2012-2013. The ERP prevalence, clinical characteristics and ECG morphology were investigated in volunteers. Results: ERP was present in 136 out of 1,424 people (9.6%).... 

    Introducing a distributed model of the heart

    , Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 419-424 ; 21551774 (ISSN) ; 9781457711992 (ISBN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    2012
    Abstract
    Conventional models of cardiovascular system (CV) frequently lack required detail. Once utilized to study the heart function, these models focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the CV system. It utilizes non-invasive blood flow and pressure seed data and temporal cardiac muscle regional activation to predict the operation of the heart. Proposed localized analysis considers specific regions of the heart, namely base, mid and apex sections of the left ventricle. This modular system is based on a hydraulic electric analogy model, estimating desired parameters, namely resistance (R), compliance (C),... 

    Prediction of acute hypotension episodes using Logistic Regression model and Support Vector Machine: A comparative study

    , Article 2011 19th Iranian Conference on Electrical Engineering, ICEE 2011, 17 May 2011 through 19 May 2011 ; May , 2011 , Page(s): 1 - 4 ; ISSN :21647054 ; 9789644634284 (ISBN) Janghorbani, A ; Arasteh, A ; Moradi, M. H ; Sharif University of Technology
    2011
    Abstract
    Acute hypotension episodes are one of the hemodynamic instabilities with high mortality rate that is frequent among many groups of patients. Prediction of acute hypotension episodes can help clinicians to diagnose the cause of this physiological disorder and select proper treatment based on this diagnosis. In this study new physiological time series are generated based on heart rate, systolic blood pressure, diastolic blood pressure and mean blood pressure time series. Statistical features of these time series are extracted and patients whom are exposed to acute hypotension episodes in future 1 hour time interval and whom are not, are classified based on these features and with the aid of... 

    Fsi simulation of a healthy coronary bifurcation for studying the mechanical stimuli of endothelial cells under different physiological conditions

    , Article Journal of Mechanics in Medicine and Biology ; Volume 15, Issue 5 , October , 2015 ; 02195194 (ISSN) Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    Atherosclerosis is a world-spread and well-known disease. This disease strongly relates to the endothelial cells (ECs) function. Normally, the endothelial cells align in the flow direction in the atheroprotected sites; however, in the case of atheroprone sites these cells orient randomly. The mechanical stimuli such as wall shear stress and strains could determine the morphology and function of the endothelial cells. In the present study, we numerically simulated the left main coronary artery (LCA) and its branches to left anterior descending (LAD) and left circumflex coronary (LCX) artery using fluid-structure interaction (FSI) modeling. The results were presented as longitudinal and... 

    Fluid-structure interaction simulation of blood flow and cerebral aneurysm: effect of partly blocked vessel

    , Article Journal of Vascular Research ; Volume 56, Issue 6 , 2019 , Pages 296-307 ; 10181172 (ISSN) Saeedi, M ; Shamloo, A ; Mohammadi, A ; Sharif University of Technology
    S. Karger AG  2019
    Abstract
    In this study, using fluid-structure interaction (FSI), 3-dimensional blood flow in an aneurysm in the circle of Willis-which is located in the middle cerebral artery (MCA)-has been simulated. The purpose of this study is to evaluate the effect of a partly blocked vessel on an aneurysm. To achieve this purpose, two cases have been investigated using the FSI method: in the first case, an ideal geometry of aneurysm in the MCA has been simulated; in the second case, modeling is performed for an ideal geometry of the aneurysm in the MCA with a partly blocked vessel. All boundary conditions, properties and modeling methods were considered the same for both cases. The only difference between the... 

    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... 

    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... 

    Analysis of the effect of ageing on rising edge characteristics of the photoplethysmogram using a modified windkessel model

    , Article Cardiovascular Engineering ; Volume 7, Issue 4 , 2007 , Pages 172-181 ; 15678822 (ISSN) Zahedi, E ; Chellappan, K ; Mohd Ali, M. A ; Singh, H ; Sharif University of Technology
    2007
    Abstract
    Ageing is one of the main contributing factors towards increasing arterial stiffness, leading to changes in peripheral pulses propagation. Therefore the characteristics of the photoplethysmogram (PPG) pulse, especially the rising edge and peak position, are greatly affected. In this study, the PPG pulse rising edge and corresponding peak position have been investigated non-invasively in human subjects as a function of age. Fifteen healthy subjects were selected and grouped in five age intervals, from 20 to 59 years, based on their comparable systolic-diastolic blood pressure and PPG amplitude. As expected, the peripheral pulse shows a steep rise and early peak in younger subjects. With age,... 

    Margination and adhesion of micro- and nanoparticles in the coronary circulation: A step towards optimised drug carrier design

    , Article Biomechanics and Modeling in Mechanobiology ; Volume 17, Issue 1 , 2018 , Pages 205-221 ; 16177959 (ISSN) Forouzandehmehr, M ; Shamloo, A ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    Obstruction of left anterior descending artery (LAD) due to the thrombosis or atherosclerotic plaques is the leading cause of death worldwide. Targeted delivery of drugs through micro- and nanoparticles is a very promising approach for developing new strategies in clot-busting or treating restenosis. In this work, we modelled the blood flow characteristics in a patient-specific reconstructed LAD artery by the fluid–solid interaction method and based on physiological boundary conditions. Next, we provided a Lagrangian description of micro- and nanoparticles dynamics in the blood flow considering their Brownian motion and the particle–particle interactions. Our results state that the number of... 

    Utility of a nonlinear joint dynamical framework to model a pair of coupled cardiovascular signals

    , Article IEEE Journal of Biomedical and Health Informatics ; Volume 17, Issue 4 , 2013 , Pages 881-890 ; 21682194 (ISSN) Sayadi, O ; Shamsollahi, M. B ; Sharif University of Technology
    2013
    Abstract
    We have recently proposed a correlated model to provide a Gaussian mixture representation of the cardiovascular signals, with promising results in identifying rhythm disturbances. The approach provides a transformation of the data into a set of integrable Gaussians distributed over time. Looking into the model from a new joint modeling perspective, it is capable of assembling a filtered estimation, and can be used to derive temporal information of the waveforms. In this paper, we present a step-by-step derivation of the joint model putting correlation assumptions together to conclude a minimal joint description for a pair of ECG-ABP signals. We then probe novel applications of this model,... 

    Joint edge detection and motion estimation of cardiac MR image sequence by a phase field method

    , Article Computers in Biology and Medicine ; Volume 40, Issue 1 , 2010 , Pages 21-28 ; 00104825 (ISSN) Eslami, A ; Jahed, M ; Preusser, T ; Sharif University of Technology
    Abstract
    In this paper a variational framework for joint segmentation and motion estimation is employed for inspecting heart in Cine MRI sequences. A functional including Mumford-Shah segmentation and optical flow based dense motion estimation is approximated using the phase-field technique. The minimizer of the functional provides an optimum motion field and edge set by considering both spatial and temporal discontinuities. Exploiting calculus of variation principles, multiple partial differential equations associated with the Euler-Lagrange equations of the functional are extracted, first. Next, the finite element method is used to discretize the resulting PDEs for numerical solution. Several... 

    Cuffless blood pressure estimation algorithms for continuous health-care monitoring

    , Article IEEE Transactions on Biomedical Engineering ; Volume 64, Issue 4 , 2017 , Pages 859-869 ; 00189294 (ISSN) Kachuee, M ; Kiani, M. M ; Mohammadzade, H ; Shabany, M ; Sharif University of Technology
    IEEE Computer Society  2017
    Abstract
    Goal: Continuous blood pressure (BP) monitoring can provide invaluable information about individuals' health conditions. However, BP is conventionally measured using inconvenient cuff-based instruments, which prevents continuous BP monitoring. This paper presents an efficient algorithm, based on the pulse arrival time (PAT), for the continuous and cuffless estimation of the systolic BP, diastolic blood pressure (DBP), and mean arterial pressure (MAP) values. Methods: The proposed framework estimates the BP values through processing vital signals and extracting two types of features, which are based on either physiological parameters or whole-based representation of vital signals. Finally,... 

    Association of glomerular and tubular dysfunction with glycaemic control, lipid, lipoprotein, apolipoprotein and antioxidant status in type 2 diabetes mellitus

    , Article Singapore Medical Journal ; Volume 48, Issue 9 , 2007 , Pages 840-846 ; 00375675 (ISSN) Farvid, M. S ; Djalali, M ; Siassi, F ; Farvid, S. S ; Sharif University of Technology
    Singapore Medical Association  2007
    Abstract
    Introduction: This study was conducted to investigate the relationship of glomerular and tubular dysfunctions with glycaemic control, lipid, lipoprotein, apolipoproteins and antioxidant status in 72 patients with type 2 diabetes mellitus. Methods: Urine albumin concentration was measured by immunoturbidimetric and urine N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities with colorimetric methods. Glycated haemoglobin was measured using affinity chromatography. Erythrocyte glu ta thione reductase and glutathione peroxidase activities and serum levels of malondialdehyde, lipids, lipoproteins and apolipoproteins were determined in patients with type 2 diabetes...