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Author: search.filters.author.Chaichana, ThanapongSubject: search.filters.subject.Simulation

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    Flow simulation in coronary artery models: An investigation of the effect of variable angulations at the left coronary artery
    (2010-12-01)
    Chaichana, Thanapong
    ;
    Sun, Zhonghua
    ;
    Tungjitkusolmun, Supan
    ;
    Sangworasil, Manas
    This study was designed to investigate the hemodynamics in the left coronary artery with the aim of identifying the relationship between angulations of left coronary bifurcation and development of atherosclerosis. Six 3D left coronary models were simulated for computational fluid dynamic analysis. The left coronary model was composed of left main stem, left anterior descending and left circumflex branches. The angulations at the left bifurcation were simulated with angles ranging from 90°, 75°, 60°, 45°, 30° to 15°. The computational fluid dynamic was used for analysis of flow velocity, wall pressure and wall shear stress. Our results showed that apparent low shear stress and high wall pressure was noticed at the left coronary bifurcation regions with wide angled models. Flow pattern was also changed with angled becoming wide in the simulated models. Our analysis shows direction relationship between coronary angulation and development of atherosclerosis. Future studies are required to perform computational fluid dynamic analysis in coronary models from patients' data with different degree of coronary stenosis. © 2010 IEEE.
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    Investigation of the hemodynamic effect of stent wires on renal arteries in patients with abdominal aortic aneurysms treated with suprarenal stent-grafts
    (2009-07-01)
    Sun, Zhonghua
    ;
    Chaichana, Thanapong
    The purpose of the study was to investigate the hemodynamic effect of stent struts (wires) on renal arteries in patients with abdominal aortic aneurysms (AAAs) treated with suprarenal stent-grafts. Two sample patients with AAA undergoing multislice CT angiography pre- and postsuprarenal fixation of stent-grafts were selected for inclusion in the study. Eight juxtarenal models focusing on the renal arteries were generated from the multislice CT datasets. Four types of configurations of stent wires crossing the renal artery ostium were simulated in the segmented aorta models: a single wire crossing centrally, a single wire crossing peripherally, a V-shaped wire crossing centrally, and multiple wires crossing peripherally. The blood flow pattern, flow velocity, wall pressure, and wall shear stress at the renal arteries pre- and post-stent-grafting were analyzed and compared using a two-way fluid structure interaction analysis. The stent wire thickness was simulated with a diameter of 0.4, 1.0, and 2.0 mm, and hemodynamic analysis was performed at different cardiac cycles. The interference of stent wires with renal blood flow was mainly determined by the thickness of stent wires and the type of configuration of stent wires crossing the renal ostium. The flow velocity was reduced by 20-30% in most of the situations when the stent wire thickness increased to 1.0 and 2.0 mm. Of the four types of configuration, the single wire crossing centrally resulted in the highest reduction of flow velocity, ranging from 21% to 28.9% among three different wire thicknesses. Wall shear stress was also dependent on the wire thickness, which decreased significantly when the wire thickness reached 1.0 and 2.0 mm. In conclusion, our preliminary study showed that the hemodynamic effect of suprarenal stent wires in patients with AAA treated with suprarenal stent-grafts was determined by the thickness of suprarenal stent wires. Research findings in our study are useful for follow-up of patients treated with suprarenal stent-grafts to ensure long-term safety of the suprarenal fixation. © 2009 Springer Science+Business Media, LLC.
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    Effect of fenestrated stents on the renal arteries: Investigation of hemodynamic changes in abdominal aortic aneurysms treated with fenestrated endovascular grafts
    (2008-12-01)
    Sun, Zhonghua
    ;
    Chaichana, Thanapong
    ;
    Tangjitkusolmun, Supan
    ;
    Sangwatthana, Surasak
    ;
    Allen, Yvonne B.
    This article uses a novel method of combining 3D image visualization and computational fluid dynamics to investigate the potential effect of fenestrated stents on the renal arteries in terms of blood flow pattern, flow rate at different cardiac cycles, based on patients with abdominal aortic aneurysm treated with fenestrated stent grafts. 3D imaging appearance of the fenestrated stents inserted into the renal arteries is used to guide the simulation of the stent protrusion into the abdominal aorta model for analysis of hemodynamic changes. A circular stent protrusion with a length of between 5-7 mm inside the abdominal aorta is simulated in two aorta models, and computational fluid dynamics is performed to detect the change of flow pattern and flow rate at the renal arteries. Our results demonstrate change of the renal flow rate is minimal following implantation of fenestrated stents, indicating the safety of fenestrated stent graft repair of patients with aortic aneurysms. © 2008 IEEE.