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Visualization of multiphase pulsatile blood over single phase blood flow in a patient specific stenosed left coronary artery using image processing technique

Athani A, Ghazali NNN, Anjum Badruddin I, Kamangar S, Salman Ahmed NJ, Honnutagi A

Biomed Mater Eng, 2023;34(1):13-35.
PMID: 36278331 DOI: 10.3233/BME-211333

BACKGROUND: Coronary arteries disease has been reported as one of the principal roots of deaths worldwide.
OBJECTIVE: The aim of this study is to analyze the multiphase pulsatile blood flow in the left coronary artery tree with stenosis.
METHODS: The 3D left coronary artery model was reconstructed using 2D computerized tomography (CT) scan images. The Red Blood Cell (RBC) and varying hemodynamic parameters for single and multiphase blood flow conditions were analyzed.
RESULTS: Results asserted that the multiphase blood flow modeling has a maximum velocity of 1.017 m/s and1.339 m/s at the stenosed region during the systolic and diastolic phases respectively. The increase in Wall Shear Stress (WSS) observed at the stenosed region during the diastole phase as compared during the systolic phase. It was also observed that the highest Oscillatory Shear Index (OSI) regions are found in the downstream area of stenosis and across the bifurcations. The increase in RBCs velocity from 0.45 m/s to 0.6 m/s across the stenosis was also noticed.
CONCLUSION: The computational multiphase blood flow analysis improves the understanding and accuracy of the complex flow conditions of blood elements (RBC and Plasma) and provides the progression of the disease development in the coronary arteries. This study helps to enhance the diagnosis of the blocked (stenosed) arteries more precisely compared to the single-phase blood flow modeling.
Topography, wetting, and corrosion responses of electrodeposited hydroxyapatite and fluoridated hydroxyapatite on magnesium

Assadian M, Jafari H, Ghaffari Shahri SM, Idris MH, Almasi D

Biomed Mater Eng, 2016 Aug 12;27(2-3):287-303.
PMID: 27567782 DOI: 10.3233/BME-161585

In this study, different types of calcium-phosphate phases were coated on NaOH pre-treated pure magnesium. The coating was applied by electrodeposition method in order to provide higher corrosion resistance and improve biocompatibility for magnesium. Thickness, surface morphology and topography of the coatings were analyzed using optical, scanning electron and atomic-force microscopies, respectively. Composition and chemical bonding, crystalline structures and wettability of the coatings were characterized using energy-dispersive and attenuated total reflectance-Fourier transform infrared spectroscopies, grazing incidence X-ray diffraction and contact angle measurement, respectively. Degradation behavior of the coated specimens was also investigated by potentiodynamic polarization and immersion tests. The experiments proved the presence of a porous coating dominated by dicalcium-phosphate dehydrate on the specimens. It was also verified that the developed hydroxyapatite was crystallized by alkali post-treatment. Addition of supplemental fluoride to the coating electrolyte resulted in stable and highly crystallized structures of fluoridated hydroxyapatite. The coatings were found effective to improve biocompatibility combined with corrosion resistance of the specimens. Noticeably, the fluoride supplemented layer was efficient in lowering corrosion rate and increasing surface roughness of the specimens compared to hydroxyapatite and dicalcium-phosphate dehydrates layers.
The influence of curvature wall on the blood flow in stenosed artery: A computational study

Ahamad NA, Kamangar S, Badruddin IA

Biomed Mater Eng, 2018;29(3):319-332.
PMID: 29578467 DOI: 10.3233/BME-181734

The current study investigates the curvature effect due to various angles of curvature on the blood flow in human artery. The stenosis is considered to have three sizes 70%, 80% and 90% blockage before the curve section of artery. Numerical study of four different angle of curvature was considered to understand the flow behavior of artery having various curvatures, on the hemodynamics factors that includes drop in arterial pressure, flow velocity as well as wall shear stress. It was found that, the augmentation of the flow resistance due to the curvature increases in presence of stenosis. It was also noted that the wall shear is higher at the outer wall as compared to the inside wall in four models considered. Results showed that both the curvature of artery and size of the stenosis have significant impact. These two factors should be considered by cardiologist to assess the complexity of stenosis.
The potential of iRest in measuring the hand function performance of stroke patients

Abdul Rahman H, Khor KX, Yeong CF, Su EL, Narayanan AL

Biomed Mater Eng, 2017;28(2):105-116.
PMID: 28372264 DOI: 10.3233/BME-171660

BACKGROUND: Clinical scales such as Fugl-Meyer Assessment (FMA) and Motor Assessment Scale (MAS) are widely used to evaluate stroke patient's motor performance. However, there are several limitations with these assessment scales such as subjectivity, lack of repeatability, time-consuming and highly depend on the ability of the physiotherapy. In contrast, robot-based assessments are objective, repeatable, and could potentially reduce the assessment time. However, robot-based assessments are not as well established as conventional assessment scale and the correlation to conventional assessment scale is unclear.
OBJECTIVE: This study was carried out to identify important parameters in designing tasks that efficiently assess hand function of stroke patients and to quantify potential benefits of robotic assessment modules to predict the conventional assessment score with iRest.
METHODS: Twelve predictive variables were explored, relating to movement time, velocity, strategy, accuracy and smoothness from three robotic assessment modules which are Draw I, Draw Diamond and Draw Circle. Regression models using up to four predictors were developed to describe the MAS.
RESULTS: Results show that the time given should be not too long and it would affect the trajectory error. Besides, result also shows that it is possible to use iRest in predicting MAS score.
CONCLUSION: There is a potential of using iRest, a non-motorized device in predicting MAS score.
New bioactive glass-ceramic: synthesis and application in PMMA bone cement composites

Abd Samad H, Jaafar M, Othman R, Kawashita M, Abdul Razak NH

Biomed Mater Eng, 2011;21(4):247-58.
PMID: 22182792 DOI: 10.3233/BME-2011-0673

In present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleation temperature and different temperature on crystallization at 850, 950 and 1000 °C. The glass-ceramic heat-treated at 950 °C was selected as bioactive filler in commercial PMMA bone cement; (PALACOS® LV) due to its ability to form 2 high crystallization phases in comparison with 850 and 1000 °C. The results of this newly glass-ceramic filled PMMA bone cement at 0-16 wt% of filler loading were compared with those of hydroxyapatite (HA). The effect of different filler loading on the setting properties was evaluated. The peak temperature during the polymerization of bone cement decreased when the liquid to powder (L/P) ratio was reduced. The setting time, however, did not show any trend when filler loading was increased. In contrast, dough time was observed to decrease with increased filler loading. Apatite morphology was observed on the surface of the glass-ceramic and selected cement after bioactivity test.