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    The pulsatile flow of Oldroyd-B fluid in a multi-stenosis artery with a time-dependent wall

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 224, Issue 4 , 2010 , Pages 915-923 ; 09544062 (ISSN) Javadzadegan, A ; Fakhimghanbarzadeh, B ; Sharif University of Technology
    In this study, the fundamental problem of unsteady blood flow in a tube with multi-stenosis is studied. An appropriate shape of the time-dependent multi-stenosis which is overlapping in the realm of formation of arterial narrowing is constructed mathematically. Blood is considered as a viscoelastic fluid characterized by the Oldroyd-B model. For the numerical solution of the problem, which is described by a coupled, non-linear system of partial differential equations (PDEs), with appropriate boundary conditions, the finite difference scheme is adopted. The solution is obtained by the development of an efficient numerical methodology based on the predictor-corrector method. The effects of... 

    Finger photoplethysmogram pulse amplitude changes induced by flow-mediated dilation

    , Article Physiological Measurement ; Volume 29, Issue 5 , 2008 , Pages 625-637 ; 09673334 (ISSN) Zahedi, E ; Jaafar, R ; Mohd Ali, M. A ; Mohamed, A. L ; Maskon, O ; Sharif University of Technology
    This study was conducted to investigate the utility and efficacy of finger photoplethysmogram pulse amplitude (PPG-AC) in comparison with the standard Doppler ultrasound in assessing an endothelial function via flow-mediated dilation (FMD). High-resolution B-mode scanning of the right brachial artery (BA) of 31 healthy subjects aged 39.7 ± 11.3 (range 22-64) years and 52 risk subjects aged 47.7 ± 10.8 (range 30-65) years were performed before and after 4 min of upper arm occlusion. Concurrent with the ultrasound measurement (where color Doppler imaging was used to enhance arterial boundary detection), PPG signals were recorded from both index fingers for cross evaluation and comparison. Our... 

    Artificial neural network for predicting the safe temporary artery occlusion time in intracranial aneurysmal surgery

    , Article Journal of Clinical Medicine ; Volume 10, Issue 7 , 2021 ; 20770383 (ISSN) Shahjouei, S ; Ghodsi, S. M ; Zangeneh Soroush, M ; Ansari, S ; Kamali Ardakani, S ; Sharif University of Technology
    MDPI  2021
    Background. Temporary artery clipping facilitates safe cerebral aneurysm management, besides a risk for cerebral ischemia. We developed an artificial neural network (ANN) to predict the safe clipping time of temporary artery occlusion (TAO) during intracranial aneurysm surgery. Method. We devised a three-layer model to predict the safe clipping time for TAO. We considered age, the diameter of the right and left middle cerebral arteries (MCAs), the diameter of the right and left A1 segment of anterior cerebral arteries (ACAs), the diameter of the anterior communicating artery, mean velocity of flow at the right and left MCAs, and the mean velocity of flow at the right and left ACAs, as well... 

    Numerical study of the effect of vascular bed on heat transfer during high intensity focused ultrasound (HIFU) ablation of the liver tumor

    , Article Journal of Thermal Biology ; Volume 86 , 2019 ; 03064565 (ISSN) Mohammadpour, M ; Firoozabadi, B ; Sharif University of Technology
    Elsevier Ltd  2019
    In this study, the influence of vascular bed comprising terminal arterial branches on heat transfer in a liver tumor exposed to high intensity focused ultrasound (HIFU) is studied numerically. Also, the effect of vascular density on temperature distribution is investigated. A coupled set of acoustics, thermal, and fluid models is used to calculate the temperature distribution in the liver. The numerical model is established based on the Westervelt and bioheat equations along with the Navier-Stokes equations. Moreover, the acoustic streaming effect is included with Newtonian and non-Newtonian flow assumptions. It is found that in a vascular bed comprising terminal arterial branches, the... 

    Time-dependent analysis of leaflets in mechanical aortic bileaflet heart valves in closing phase using the finite strip method

    , Article Medical Engineering and Physics ; Volume 28, Issue 2 , 2006 , Pages 122-133 ; 13504533 (ISSN) Mohammadi, H ; Ahmadian, M. T ; Wan, W. K ; Sharif University of Technology
    Background and aims of the study: Mechanical heart valves (MHV) are widely used to replace dysfunctional and failed heart valves. The bileaflet MHV design is very popular due to its superior hemodynamics. Since their introduction in 1977, the hemodynamics of bileaflet prostheses has been extensively studied. In this study the dynamic behaviour during the closing phase of a bileaflet MHV under normal physiological conditions has been investigated. Methods: Fluid analysis is based on the control volume with moving boundaries in the vicinity of the occluder. Unsteady continuity equation, unsteady momentum equation on the control volume and unsteady Bernoulli's equation have been used to... 

    Noninvasive detection of coronary artery disease by arterio-oscillo-graphy

    , Article IEEE Transactions on Biomedical Engineering ; Volume 52, Issue 4 , 2005 , Pages 743-747 ; 00189294 (ISSN) Pouladian, M ; Hashemi Golpayegani, M. R ; Abbaspour Tehrani Fard, A ; Bubvay Nejad, M ; Sharif University of Technology
    Coronary artery disease (CAD) causes oscillations in peripheral arteries. Oscillations of the walls of the brachial arteries of 51 patients were recorded [together with the electrocardiogram (ECG)] by an accelerometer at different cuff pressures. By analyzing the energy of the oscillations in the 30-250 Hz band, 16 of 22 patients with CAD and 26 of 29 non-CAD subjects were classified correctly, independent of the ECG, and with no effect of heart murmurs  

    Atheroprone sites of coronary artery bifurcation: Effect of heart motion on hemodynamics-dependent monocytes deposition

    , Article Computers in Biology and Medicine ; Volume 133 , 2021 ; 00104825 (ISSN) Biglarian, M ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    Elsevier Ltd  2021
    Atherosclerosis as a common cardiovascular disease is a result of both adverse hemodynamics conditions and monocyte deposition within coronary arteries. It is known that the adhesion of monocytes on the arterial wall and their interaction with the vascular surface are one of the main parameters in the initiation and progression of atherosclerosis. In this work, hemodynamic parameters and monocyte deposition have been investigated in a 3D computational model of the Left Anterior Descending coronary artery (LAD) and its first diagonal branch (D1) under the heart motion. A one-way Lagrangian approach is performed to trace the monocyte particles under different blood flow regimes and heart motion...