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Subject: search.filters.subject.Stent graft

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    Fenestrated stent graft repair of abdominal aortic aneurysm: Hemodynamic analysis of the effect of fenestrated stents on the renal arteries
    (2010-01-01)
    Sun, Zhonghua
    ;
    Chaichana, Thanapong
    Objective: We wanted to investigate the hemodynamic effect of fenestrated stents on the renal arteries with using a fluid structure interaction method. Materials and Methods: Two representative patients who each had abdominal aortic aneurysm that was treated with fenestrated stent grafts were selected for the study. 3D realistic aorta models for the main artery branches and aneurysm were generated based on the multislice CT scans from two patients with different aortic geometries. The simulated fenestrated stents were designed and modelled based on the 3D intraluminal appearance, and these were placed inside the renal artery with an intra-aortic protrusion of 5.0-7.0 mm to reflect the actual patients' treatment. The stent wire thickness was simulated with a diameter of 0.4 mm and hemodynamic analysis was performed at different cardiac cycles. Results: Our results showed that the effect of the fenestrated stent wires on the renal blood flow was minimal because the flow velocity was not significantly affected when compared to that calculated at pre-stent graft implantation, and this was despite the presence of recirculation patterns at the proximal part of the renal arteries. The wall pressure was found to be significantly decreased after fenestration, yet no significant change of the wall shear stress was noticed at post-fenestration, although the wall shear stress was shown to decrease slightly at the proximal aneurysm necks. Conclusion: Our analysis demonstrates that the hemodynamic effect of fenestrated renal stents on the renal arteries is insignificant. Further studies are needed to investigate the effect of different lengths of stent protrusion with variable stent thicknesses on the renal blood flow, and this is valuable for understanding the long-term outcomes of fenestrated repair.
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    Investigation of hemodynamic changes in abdominal aortic aneurysms treated with fenestrated endovascular grafts
    (2009-12-01)
    Sun, Zhonghua
    ;
    Chaichana, Thanapong
    ;
    Allen, Yvonne B.
    ;
    Sangworasil, Manas
    ;
    Tungjitkusolmun, Supan
    Fenestrated stent grafts are becoming widely used in clinical practice to treat patients with complicated aortic aneurysms, with short to mid-term satisfactory outcomes being achieved. However, long-term results are yet to be determined. One of the main concerns about the safety of fenestrated repair is the patency of fenestrated renal arteries and subsequent renal function. The purpose of this study is to investigate the hemodynamic changes in patients treated with fenestrated stent grafts using a two-way fluid-structure interaction. 4 patients undergoing fenestrated stent graft repair were selected for inclusion in our analysis. All of the fenestrated renal arteries remained patent after implantation of stent grafts with one patient developing post-procedural complication, endoleak. Our results showed that with insertion of fenestrated stents into the renal arteries with variable lengths, no significant changes of blood flow velocity were noticed based on the flow analysis. Our preliminary study indicates the safety of fenestrated stent grafts, however, further studies are required to verify the long-term outcome of this procedure.
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    Computational fluid analysis of blood flow characteristics in abdominal aortic aneurysms treated with suprarenal endovascular grafts
    (2009-12-01)
    Sun, Zhonghua
    ;
    Chaichana, Thanapong
    ;
    Sangworasil, Manas
    ;
    Tungjitkusolmun, Supan
    The purpose of this study is to investigate the hemodynamic effects of suprarenal stent grafts on the renal arteries in the treatment of patients with abdominal aortic aneurysm. Suprarenal stent grafts have been increasingly used for treatment of aortic aneurysms with suboptimal aneurysm necks. However, the long-term safety of this procedure is yet to be determined. 2 sample patients undergoing suprarenal stent grafting were included in the study. Four variable configurations of stent wires crossing the renal artery ostium were simulated in aorta models based on CT generated data, at different cardiac cycles. The stent wires thickness was set 0.5 mm which is similar to the actual diameter of a stent wire. Computational fluid dynamic analysis showed slightly decrease of flow velocity to the renal arteries with multiple wires crossing, and no changes of flow velocity to the renal arteries with single wire crossing. Our preliminary results demonstrated the safety of suprarenal stent grafting. Further studies are required to investigate the effect of different wire thickness on subsequent hemodynamic changes to the renal arteries.