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Ong CW, Wee IJY, Toma M, Cui F, Xu XY, Richards AM, Leo HL, Choong AMTL. Haemodynamic changes in visceral hybrid repairs of type III and type V thoracoabdominal aortic aneurysms. Sci Rep 2023; 13:13760. [PMID: 37612440 PMCID: PMC10447573 DOI: 10.1038/s41598-023-40323-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 08/08/2023] [Indexed: 08/25/2023] Open
Abstract
The visceral hybrid procedure combining retrograde visceral bypass grafting and completion endovascular stent grafting is a feasible alternative to conventional open surgical or wholly endovascular repairs of thoracoabdominal aneurysms (TAAA). However, the wide variability in visceral hybrid configurations means that a priori prediction of surgical outcome based on haemodynamic flow profiles such as velocity pattern and wall shear stress post repair remain challenging. We sought to appraise the clinical relevance of computational fluid dynamics (CFD) analyses in the setting of visceral hybrid TAAA repairs. Two patients, one with a type III and the other with a type V TAAA, underwent successful elective and emergency visceral hybrid repairs, respectively. Flow patterns and haemodynamic parameters were analysed using reconstructed pre- and post-operative CT scans. Both type III and type V TAAAs showed highly disturbed flow patterns with varying helicity values preoperatively within their respective aneurysms. Low time-averaged wall shear stress (TAWSS) and high endothelial cell action potential (ECAP) and relative residence time (RRT) associated with thrombogenic susceptibility was observed in the posterior aspect of both TAAAs preoperatively. Despite differing bypass configurations in the elective and emergency repairs, both treatment options appear to improve haemodynamic performance compared to preoperative study. However, we observed reduced TAWSS in the right iliac artery (portending a theoretical risk of future graft and possibly limb thrombosis), after the elective type III visceral hybrid repair, but not the emergency type V repair. We surmise that this difference may be attributed to the higher neo-bifurcation of the aortic stent graft in the type III as compared to the type V repair. Our results demonstrate that CFD can be used in complicated visceral hybrid repair to yield potentially actionable predictive insights with implications on surveillance and enhanced post-operative management, even in patients with complicated geometrical bypass configurations.
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Affiliation(s)
- Chi Wei Ong
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore
| | - Ian J Y Wee
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Milan Toma
- Department of Osteopathic Manipulative Medicine, College of Osteopathic Medicine, New York Institute of Technology, New York, USA
| | - Fangsen Cui
- Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Xiao Yun Xu
- Department of Chemical Engineering, Imperial College London, London, UK
| | - Arthur Mark Richards
- Cardiovascular Research Institute, National University of Singapore, Singapore, Singapore
- Christchurch Heart Institute, University of Otago, New Zealand, New Zealand
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Andrew M T L Choong
- Division of Vascular and Endovascular Surgery, Department of Cardiac, Thoracic and Vascular Surgery, National University Heart Centre, Singapore, Singapore.
- Asian Aortic & Vascular Centre, Singapore, Singapore.
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Bao J, Gan X, Feng W, Li Y, Qiu Y, Zhou M, Guo J, He L. Abnormal flow pattern of low wall shear stress and high oscillatory shear index in spontaneous vertebral artery dissection with vertebral artery hypoplasia. Front Neurosci 2023; 17:1179963. [PMID: 37389359 PMCID: PMC10303804 DOI: 10.3389/fnins.2023.1179963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 05/26/2023] [Indexed: 07/01/2023] Open
Abstract
Introduction Spontaneous vertebral artery dissection (sVAD) might tend to develop in vertebral artery hypoplasia (VAH) with hemodynamic dysfunction and it is crucial to assess hemodynamics in sVAD with VAH to investigate this hypothesis. This retrospective study aimed to quantify hemodynamic parameters in patients with sVAD with VAH. Methods Patients who had suffered ischemic stroke due to an sVAD of VAH were enrolled in this retrospective study. The geometries of 14 patients (28 vessels) were reconstructed using Mimics and Geomagic Studio software from CT angiography (CTA). ANSYS ICEM and ANSYS FLUENT were utilized for mesh generation, set boundary conditions, solve governing equations, and perform numerical simulations. Slices were obtained at the upstream area, dissection or midstream area and downstream area of each VA. The blood flow patterns were visualized through instantaneous streamline and pressure at peak systole and late diastole. The hemodynamic parameters included pressure, velocity, time-averaged blood flow, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), endothelial cell action potential (ECAP), relative residence time (RRT) and time-averaged nitric oxide production rate (TARNO). Results Significant focal increased velocity was present in the dissection area of steno-occlusive sVAD with VAH compared to other nondissected areas (0.910 m/s vs. 0.449 vs. 0.566, p < 0.001), while focal slow flow velocity was observed in the dissection area of aneurysmal dilatative sVAD with VAH according to velocity streamlines. Steno-occlusive sVAD with VAH arteries had a lower time-averaged blood flow (0.499 cm3/s vs. 2.268, p < 0.001), lower TAWSS (1.115 Pa vs. 2.437, p = 0.001), higher OSI (0.248 vs. 0.173, p = 0.006), higher ECAP (0.328 Pa-1 vs. 0.094, p = 0.002), higher RRT (3.519 Pa-1 vs. 1.044, p = 0.001) and deceased TARNO (104.014 nM/s vs. 158.195, p < 0.001) than the contralateral VAs. Conclusion Steno-occlusive sVAD with VAH patients had abnormal blood flow patterns of focal increased velocity, low time-averaged blood flow, low TAWSS, high OSI, high ECAP, high RRT and decreased TARNO. These results provide a good basis for further investigation of sVAD hemodynamics and support the applicability of the CFD method in testing the hemodynamic hypothesis of sVAD. More detailed hemodynamic conditions with different stages of sVAD are warranted in the future.
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Affiliation(s)
- Jiajia Bao
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Xinling Gan
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Wentao Feng
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University) Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Yanbo Li
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Yue Qiu
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Muke Zhou
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Jian Guo
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Li He
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
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Wang G, Li Z, Chen C, Yan F, Wei J, Zhang Z, Chen Y. The hemodynamic effect of eccentricity in visceral branched aneurysms with multilayer stents. Proc Inst Mech Eng H 2022; 236:1070-1079. [DOI: 10.1177/09544119221106829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is preliminarily acknowledged that multilayer stent (MS) is a promising alternative technology in the treatment of visceral branched aneurysms, but hemodynamic consequences of eccentricity in such aneurysms with MS are less examined. In this work, we performed a time-dependent simulation of branched aneurysms of various eccentricities with different stent layers, and thrombosis-related parameters, such as time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), and relative residence time (RRT), were also analyzed. Our results revealed that MS can generally restore laminar flow inside the stent, and allow proper perfusion to vital organs while also fostering a relatively secluded hemodynamic environment for thrombosis formation. Particularly, a flow in the aneurysm sac communicating between the main artery and side branch forms at early systole. However, MS fails to completely eliminate detrimental flow impingement after peak systole, which may hinder aneurysm recovery, especially in the cases of eccentric aneurysms. Therefore, saccular aneurysms should be treated with more caution than fusiform aneurysms. And further therapeutic attempts to keep both perfusion in the proximal region of the aneurysm and isolation in the distal region of the aneurysm should be considered.
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Affiliation(s)
- Guanshi Wang
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Zhongyou Li
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Chong Chen
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Fei Yan
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Junru Wei
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Zhuo Zhang
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Yu Chen
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu, China
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Ong CW, Kumar GP, Zuo K, Koh LB, Charles CJ, Ho P, Leo HL, Cui F. A novel coating method to reduce membrane infolding through pre-crimping of covered stents – Computationaland experimental evaluation. Comput Biol Med 2022; 145:105524. [DOI: 10.1016/j.compbiomed.2022.105524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 11/24/2022]
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Nada A, Fakhr M, Elwakad M, Ali M. A Finite Element Based Analysis of a Hemodynamics Efficient Flow Stent Suitable for Different Abdominal Aneurysm Shapes. J Biomech Eng 2022; 144:1137925. [PMID: 35237800 DOI: 10.1115/1.4053999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Indexed: 11/08/2022]
Abstract
This research aimed to examine the impact of a proposed flow stent (PFS) on different abdominal artery shapes. For that purpose, a finite element-based model using the computational fluid dynamics (CFD) method is developed. The effect of PFS intervention on the hemodynamic efficiency is estimated by all of the significant criteria used for the evaluation of aneurysm occlusion and possible rupture; the flow velocity, pressure, wall shear stress (WSS), and WSS-related indices. Results showed that PFS intervention preserves the effects of high flow rate and decreases irregular flow recirculation in the sac of the aneurysm. The flow velocity decreases inside the aneurysm sac in the range of 55% to 80%. The time-averaged wall shear stress (TAWSS) was reduced from 42% to 53% by FPS deployment. The simulation results implies that PFS could heal an aneurysm efficiently with a mechanism that causes the development of thrombus and ultimately leads to aneurysm resorption.
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Affiliation(s)
- Ayat Nada
- Department of Computers and Systems, Electronics Research Institute, Cairo, Egypt
| | - Mahmoud Fakhr
- Department of Computers and Systems, Electronics Research Institute, Cairo, Egypt
| | - Mohamed Elwakad
- Department of Biomedical Engineering, Faculty of Engineering & Technology, Future University, Cairo, Egypt
| | - Mohamed Ali
- Department of Biomedical Engineering, Faculty of Engineering, Helwan University, Cairo, Egypt
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Li Z, Jiang W, Salerno S, Li Y, Chen Y, Xu Z, Wang G. Acute Hemodynamic Improvement by Thermal Vasodilation inside the Abdominal and Iliac Arterial Segments of Young Sedentary Individuals. J Vasc Res 2021; 58:191-206. [PMID: 33823509 DOI: 10.1159/000514588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/19/2021] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To study the hemodynamic response to lower leg heating intervention (LLHI) inside the abdominal and iliac arterial segments (AIAS) of young sedentary individuals. METHODS A Doppler measurement of blood flow was conducted for 5 young sedentary adults with LLHI. Heating durations of 0, 20, and 40 min were considered. A lumped parameter model (LPM) was used to ascertain the hemodynamic mechanism. The hemodynamics were determined via numerical approaches. RESULTS Ultrasonography revealed that the blood flow waveform shifted upwards under LLHI; in particular, the mean flow increased significantly (p < 0.05) with increasing heating duration. The LPM showed that its mechanism depends on the reduction in afterload resistance, not on the inertia of blood flow and arterial compliance. The time-averaged wall shear stress, time-averaged production rate of nitric oxide, and helicity in the external iliac arteries increased more significantly than in other segments as the heating duration increased, while the oscillation shear index (OSI) and relative residence time (RRT) in the AIAS declined with increasing heating duration. There was a more obvious helicity response in the bilateral external iliac arteries than the OSI and RRT responses. CONCLUSION LLHI can effectively induce a positive hemodynamic environment in the AIAS of young sedentary individuals.
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Affiliation(s)
- Zhongyou Li
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture & Environment, Sichuan University, Chengdu, China
| | - Wentao Jiang
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture & Environment, Sichuan University, Chengdu, China
| | - Stephen Salerno
- Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Yi Li
- Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Yu Chen
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture & Environment, Sichuan University, Chengdu, China
| | - Zhi Xu
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture & Environment, Sichuan University, Chengdu, China.,Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Kowloon, China
| | - Guanshi Wang
- Laboratory of Biomechanical Engineering, Department of Applied Mechanics, College of Architecture & Environment, Sichuan University, Chengdu, China
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Sun A, Zhao C, Gao Z, Deng X, Qiu H. A proposed design of flow diverter and it’s hemodynamic validation. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021. [DOI: 10.1016/j.medntd.2020.100049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Elhelali A, Sultan S, Hynes N, Delassus P, Kavanagh EP, Fahy P, Stefanov F, Morris L. Evaluation of aortic arch aneurysms treated with the streamliner multilayer flow modulator. ITALIAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY 2020. [DOI: 10.23736/s1824-4777.20.01444-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Song C, Cai Q, Huang Y, Lu Q. Multilayer bare stent technique in treating intact mycotic suprarenal aortic aneurysm: a case report. EUROPEAN HEART JOURNAL-CASE REPORTS 2020; 4:1-5. [PMID: 33442625 PMCID: PMC7793158 DOI: 10.1093/ehjcr/ytaa361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 04/14/2020] [Accepted: 09/10/2020] [Indexed: 11/29/2022]
Abstract
Background Invasive aspergillosis (IA) related mycotic aortic aneurysm is rare in immunocompetent patient. The endovascular therapy remains controversial due to potential risk of graft infection, while the suprarenal cases might face catastrophic complications during open surgery. Case summary We presented an IA case with suprarenal abdominal aortic aneurysm confirmed by joint effusion. Multilayer bare stent technique was performed to preserve visceral blood flow and promote aneurysmal thrombus formation, along with antifungal treatment. Two years of follow-up revealed complete aneurysm thrombosis without evidence of infection. Discussion Fungal infection that affects the aorta is difficult to recognize due to often negative blood cultures. Close observation is recommended in case of suspicion of mycotic aneurysms. Multilayer bare stent technique can restore luminal laminar blood flow and reduce the risk of infection in intact mycotic suprarenal aortic aneurysm.
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Affiliation(s)
- Chao Song
- Department of Vascular Surgery, Shanghai Changhai Hospital, Navy Medical University, Shanghai 200082, People's Republic of China
| | - Qing Cai
- Department of Department of Rheumatology and Immunology, Shanghai Changhai Hospital, Navy Medical University, Shanghai, People's Republic of China
| | - Yi Huang
- Department of Respiratory Medicine, Shanghai Changhai Hospital, Navy Medical University, Shanghai, People's Republic of China
| | - Qingsheng Lu
- Department of Vascular Surgery, Shanghai Changhai Hospital, Navy Medical University, Shanghai 200082, People's Republic of China
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He R, Zhao L, Silberschmidt V, Liu Y, Vogt F. Patient-specific modelling of stent overlap: Lumen gain, tissue damage and in-stent restenosis. J Mech Behav Biomed Mater 2020; 109:103836. [DOI: 10.1016/j.jmbbm.2020.103836] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/09/2020] [Accepted: 04/26/2020] [Indexed: 10/24/2022]
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Zhongyou L, Chong C, Yu C, Guanshi W, Wentao J. Optimization of fenestrated technique in application to aortic aneurysms with an attached branch. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2020. [DOI: 10.1016/j.medntd.2020.100037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Stockle J, Romero DA, Amon CH. Optimization of porous stents for endovascular repair of abdominal aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3336. [PMID: 32212322 DOI: 10.1002/cnm.3336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 01/21/2020] [Accepted: 03/17/2020] [Indexed: 06/10/2023]
Abstract
This study presents a simulation-based methodology to design porous stents to induce suitable hemodynamic environments inside abdominal aortic aneurysm (AAA) sacs. In the proposed methodology, an optimization algorithm iteratively modifies the porosity distribution of the stent and executes a computational fluid dynamics (CFD) simulation to determine the effect of these changes on the hemodynamic conditions inside the aneurysm sac. The optimization iterations proceed until relevant hemodynamic parameters are within ranges prescribed a priori by the user as desirable to control the progression of the AAA. The resulting porosity distribution uniquely describes the porous stent design that can control the hemodynamic environment (eg, shear stress at the aneurysm wall, pressure distribution, residence time), reducing AAA rupture risks and improving treatment efficacy. To demonstrate its potential, the proposed methodology is applied to idealized AAA geometry under steady-state flow conditions, though it may be easily applied to more complex AAA geometries under transient, pulsatile flow conditions. The proposed methodology has the potential to enable the design of a new generation of porous stents tailored to patient-specific geometries and flow conditions, to improve patient outcomes.
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Affiliation(s)
- Juan Stockle
- Escuela de Ingenieria Industrial, Universidad Diego Portales, Santiago, Chile
| | - David A Romero
- Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Cristina H Amon
- Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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Oran I, Cinar C, Bozkaya H, Parildar M, Duman S. Reduced Activity of von Willebrand Factor after Flow-Diverting Stent Implantation for Intracranial Aneurysms: A Link to Acquired von Willebrand Disease? AJNR Am J Neuroradiol 2020; 41:140-146. [PMID: 31896567 DOI: 10.3174/ajnr.a6343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 10/20/2019] [Indexed: 12/26/2022]
Abstract
BACKGROUND AND PURPOSE Vascular devices generating high shear stress can cause type 2A acquired von Willebrand disease, which is characterized by low von Willebrand factor activity accompanied by hemorrhagic complications. The braided mesh structure of flow-diverting stents with a relatively small strut size can create abnormally high shear stress while arterial blood flows through the stent struts into the aneurysm, and flow-diverting stent may be associated with reduced von Willebrand factor activity. MATERIALS AND METHODS Aneurysmal morphologic parameters and patient data were examined retrospectively among patients who had an unruptured intracranial aneurysm treated with a flow-diverting stent. The RISTOtest (test for whole blood ristocetin-induced platelet aggregation) for von Willebrand factor activity, as well as tests for aspirin and clopidogrel/prasugrel effectiveness, were performed immediately before the endovascular procedure and 24 hours later by multiple electrode aggregometry. RESULTS A total of 39 patients with 56 aneurysms were recruited, and statistical analyses were performed in 32 patents with 49 aneurysms. Compared with the baseline values, von Willebrand factor activity was reduced in 16 patients but increased in 23 patients. Aneurysmal variables (eg, neck area, volume, volume-to-neck area ratio, size ratio, and morphologic index) clearly distinguished patients with reduced von Willebrand factor activity from those with nonreduced von Willebrand factor activity. The receiver operating characteristic curve showed that the morphologic index and volume had the highest discriminative power, with an area under the curve of 0.99. CONCLUSIONS In high-volume/large-neck aneurysms, flow-diverting stent implantation can cause reduced von Willebrand factor activity, which may be linked causally to acquired von Willebrand disease.
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Affiliation(s)
- I Oran
- From the Departments of Radiology (I.O., C.C., H.B., M.P.) .,Dr Oran is currently affiliated with Section of Interventional Radiology, KENT Hospital, Izmir, Turkey
| | - C Cinar
- From the Departments of Radiology (I.O., C.C., H.B., M.P.)
| | - H Bozkaya
- From the Departments of Radiology (I.O., C.C., H.B., M.P.)
| | - M Parildar
- From the Departments of Radiology (I.O., C.C., H.B., M.P.)
| | - S Duman
- Internal Medicine (S.D.), Ege University Medical School, Izmir, Turkey
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Dai Y, Luo G, Dai X, Liu H. Hemodynamic Effects of Multiple Overlapping Uncovered Stents on Aortic Dissection: Surgical Strategies and Implications for False Lumen Thrombosis. Cardiovasc Eng Technol 2019; 11:24-35. [PMID: 31820352 DOI: 10.1007/s13239-019-00443-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 11/20/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE Multiple overlapping uncovered stents (MOUS) are employed to promote false lumen thrombosis in the aortic dissections (AD), when the tears are in close vicinity to the branch vessels. However, the overall rate of false lumen thrombosis remains unsatisfactory. This study was performed to investigate the hemodynamic influence of MOUS on aortic dissection to shed some light on the mechanism of post-stenting false lumen thrombosis. METHODS An anatomically accurate computational fluid dynamics model was developed to investigate the hemodynamics of AD. A parametric study was carried out to demonstrate the hemodynamic influence of MOUS in various post-surgery scenarios featuring the representative surgical strategies involving MOUS. RESULTS The use of reduced-porosity MOUS slowed the blood flow in the false lumen and decreased the wall shear stress. MOUS depressed the false lumen and enlarged the true lumen, without significantly altering the blood outflow distribution among the branch vessels. Compared with MOUS-alone and stent graft-alone scenarios, the combination of MOUS and stent graft generated a substantially large region of stagnant flow. The active flow was confined to an area in close vicinity to the tears covered by the MOUS, which perfuse the right renal artery in the false lumen. CONCLUSIONS MOUS helps to generate a favored hemodynamic environment for thrombus formation in the false lumen. Application of MOUS along with covered stent grafts may represent a more effective treatment for AD than utilizing MOUS or stent graft alone.
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Affiliation(s)
- Yanan Dai
- Department of Mechanics, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Guangze Luo
- Department of Surgery, Tianjin Medical University General Hospital, 154 Anshan Road, Tianjin, 300052, China
| | - Xiangchen Dai
- Department of Surgery, Tianjin Medical University General Hospital, 154 Anshan Road, Tianjin, 300052, China.
| | - Haofei Liu
- Department of Mechanics, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
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Treatment of High Surgical Risk Thoracoabdominal Aortic Aneurysms with Stent Graft and Multilayer Bare Stents Joint Technique: Mid-Long-Term Clinical Results. Ann Vasc Surg 2019; 63:108-116. [PMID: 31536795 DOI: 10.1016/j.avsg.2019.06.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 06/20/2019] [Accepted: 06/30/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND This study aims to present the performance data on stent-graft and multilayer bare stents (MBS) joint technique in the treatment of high-risk thoracoabdominal aortic aneurysm (TAAA). METHODS From May 2012 to December 2015, 8 selective TAAA cases (ages 46-75 years) ineligible for surgical repair underwent the stent-graft and MBS joint procedure, and were closely followed up for a median of 32 months (range 14-58). Using computed tomography images, the aneurysm size, luminal blood flow diameter, and the covered visceral branches were analyzed. RESULTS Technical success was achieved in all patients (100%, 8/8). Twenty-four visceral branches were covered by MBS in total. There was no complication or death during hospital stay. During follow-up period, no death or complication occurred. Aneurysm shrinkage (maximum diameter decrease ≥5 mm) was observed in 7 patients. No aneurysm expansion was observed. Total aneurysm sac thrombosis was observed in all patients. The majority of covered side branches (23/24) were successfully preserved. No visceral ischemia or bleeding complications was observed during follow-up. CONCLUSIONS Total endovascular repair of TAAA using stent-graft and MBS joint technique may be a safe and effective alternative in high surgical risk patients. More approving clinical evidences about the safety and efficacy of this procedure are anticipated.
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Gimnich OA, Singh J, Bismuth J, Shah DJ, Brunner G. Magnetic resonance imaging based modeling of microvascular perfusion in patients with peripheral artery disease. J Biomech 2019; 93:147-158. [PMID: 31331663 PMCID: PMC7390497 DOI: 10.1016/j.jbiomech.2019.06.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 11/20/2022]
Abstract
Peripheral artery disease (PAD) is associated with an increased risk of adverse cardiovascular events, impaired lower extremity blood flow and microvascular perfusion abnormalities in the calf muscles which can be determined with contrast-enhanced magnetic resonance imaging (CE-MRI). We developed a computational model of the microvascular perfusion in the calf muscles. We included 20 patients (10 PAD, 10 controls) and utilized the geometry, mean signal intensity and arterial input functions from CE-MRI calf muscle perfusion scans. The model included the microvascular pressure (pv), outflow filtration coefficient (OFC), transfer rate constant (kt), porosity (φ), and the interstitial permeability (Ktissue). Parameters were fitted and the simulations were compared across PAD patients and controls. Intra-observer reproducibility of the simulated mean signal intensities was excellent (intraclass correlation coefficients >0.995). kt and Ktissue were higher in PAD patients compared with controls (4.72 interquartile range (IQR) 3.33, 5.56 vs. 2.47 IQR 2.10, 2.85; p = 0.003; and 3.68 IQR 3.18, 4.41 vs. 1.81 IQR 1.81, 1.81; p < 0.001). Conversely, porosity (φ) was lower in PAD patients compared with controls (0.52 IQR 0.49, 0.54 vs. 0.61 IQR 0.58, 0.64; p = 0.016). Porosity (φ) was correlated with the ankle brachial index (r = 0.64, p = 0.011). The proposed computational microvascular model is robust and reproducible, and essential model parameters differ significantly between PAD patients and controls.
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Affiliation(s)
- Olga A Gimnich
- Cardiovascular Imaging Research and Data Sciences Laboratory, Department of Medicine, Baylor College of Medicine, Houston, TX, USA; Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Jaykrishna Singh
- Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston, TX, USA
| | - Jean Bismuth
- Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston, TX, USA
| | - Dipan J Shah
- Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston, TX, USA
| | - Gerd Brunner
- Cardiovascular Imaging Research and Data Sciences Laboratory, Department of Medicine, Baylor College of Medicine, Houston, TX, USA; Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston, TX, USA; Penn State Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, PA, USA..
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Li Z, Hu L, Chen C, Wang Z, Zhou Z, Chen Y. Hemodynamic Performance of Multilayer Stents in the Treatment of Aneurysms with a Branch Attached. Sci Rep 2019; 9:10193. [PMID: 31308428 PMCID: PMC6629690 DOI: 10.1038/s41598-019-46714-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 07/04/2019] [Indexed: 11/09/2022] Open
Abstract
Although multilayer stents (MSs) can be used to treat aneurysm effectively, for some aneurysms with branches attached, the hemodynamic mechanisms are still unclear. In this work, we modeled five cases that involve 1-4-layer stents implanted in aneurysms with side branches, and the numerical approach was used. Case 1 corresponds to an aneurysm without a stent, and cases 2-5 represent 1-4-layer stents being employed within aneurysms, respectively. The results showed that the velocity within the sac declined dramatically and the eddies' intensity weakened with increased number of stent layers, time-averaged wall shear stress (TAWSS), and nitric oxide production rate (TARNO) dropped linearly with increase in stent porosity, and oscillatory shear index (OSI) and relative residence time (RRT) increased evidently with MS intervention. Moreover, the MSs had a slight effect on the patency of the side branch; its flow rate was still above the normal case than without aneurysm. It can be concluded that MSs are helpful in promoting the growth of thrombus within the aneurysm through an isolated hemodynamic environment and keeping the branch unobstructed, but more clinical evidences are required.
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Affiliation(s)
- Zhongyou Li
- Department of Applied Mechanics, Sichuan University, Chengdu, 610065, China
| | - Lijuan Hu
- Third Department of Internal Medicine, Friendship Hospital, Xi'an, 710072, China
| | - Chong Chen
- College of Manufacturing Science & Engineering, Sichuan University, Chengdu, 610065, China
| | - Zhenze Wang
- Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs & Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, National Research Center for Rehabilitation Technical Aids, Beijing, 100176, China
| | - Zhihong Zhou
- Department of Applied Mechanics, Sichuan University, Chengdu, 610065, China.
| | - Yu Chen
- Department of Applied Mechanics, Sichuan University, Chengdu, 610065, China
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18
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Hemodynamic analysis of a novel stent graft design with slit perforations in thoracic aortic aneurysm. J Biomech 2019; 85:210-217. [DOI: 10.1016/j.jbiomech.2019.01.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/08/2018] [Accepted: 01/08/2019] [Indexed: 01/11/2023]
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Spinella G, Finotello A, Faggiano E, Pane B, Conti M, Gazzola V, Auricchio F, Palombo D. Midterm Follow-up Geometrical Analysis of Thoracoabdominal Aortic Aneurysms Treated with Multilayer Flow Modulator. Ann Vasc Surg 2018; 53:97-104.e2. [DOI: 10.1016/j.avsg.2018.04.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 10/28/2022]
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20
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Zhongyou L, Wentao J, Ding Y, Yu C, Xiaobao T, Zhihong Z. Investigation of the hemodynamics of a juxtarenal aortic aneurysm with intervention by dual-stents strategy. Clin Biomech (Bristol, Avon) 2018; 58:109-115. [PMID: 30075422 DOI: 10.1016/j.clinbiomech.2018.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 07/24/2018] [Accepted: 07/28/2018] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To study the feasibility of using two stents (a combination of multilayer stent [MS] and stent graft [SG]) in the treatment of a juxtarenal aortic aneurysm that involves a significant branch artery and to determine the advantages and disadvantages of using SGs upstream and downstream from the aneurysm so as to provide some theoretical guidance for preoperative clinical decision-making in the future. METHODS Four ideal geometric models were established for numerical computation: case 1 refers to an aneurysm without the use of stents, case 2 represents the implantation of two MSs in an aneurysm, and case 3 (SG + MS) and case 4 (MS + SG) both involve the treatment of an aneurysm by using a combination of SG and MG. RESULTS The aneurysm pressure is slightly lower and there are more vortices when the SG is implanted (case 3 and case 4). In particular, for case 4, additional vortices appear in the sac and the area of the low-wall shear stress is larger on the aneurysm compared with those of the other three cases. However, the pressure becomes uneven, and a peak pressure region is observed on the wall of the aneurysm, and therefore, the aneurysmal wall will become buckled. In addition, the flux of the renal artery in the four cases is greater than that in the normal case. CONCLUSION The arrangements in cases 3 and 4 can effectively isolate the aneurysm from circulation, but clinically, it is necessary to avoid such a high-risk situation wherein the SG is positioned downstream of the aneurysm (case 4), even though this leads to improved isolation.
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Affiliation(s)
- Li Zhongyou
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China
| | - Jiang Wentao
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China
| | - Yuan Ding
- Department of Vascular Surgery of West China Hospital, Sichuan University, Chengdu 610065, China
| | - Chen Yu
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China.
| | - Tian Xiaobao
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China.
| | - Zhou Zhihong
- Department of Applied Mechanics, Sichuan University, Chengdu 610065, China.
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Numerical and Experimental Investigation of the Hemodynamic Performance of Bifurcated Stent Grafts with Various Torsion Angles. Sci Rep 2018; 8:12625. [PMID: 30135573 PMCID: PMC6105657 DOI: 10.1038/s41598-018-31015-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/30/2018] [Indexed: 11/09/2022] Open
Abstract
The “crossed limbs” strategy for bifurcated stent grafts (BSGs) is widely employed when abdominal aortic aneurysm (AAA) patients have unfavorable neck or highly splayed iliac arteries. Helical flow is regarded as a typical flow pattern within the human arterial system and is believed to have the positive physiological effects of inhibiting thrombosis formation and atherosclerosis. The “crossed limbs” strategy may induce helical flow and improve the stent graft outcome. To verify the performance of this strategy by considering hemodynamics, we constructed a series of idealized BSGs with various torsion angles and evaluated the hemodynamic performance, including the helical strength, time-averaged wall shear stress (TAWSS), oscillatory shear index, relative resident time (RRT), and displacement force. Our numerical results indicate that an increased torsion angle enhances the helicity strength at the iliac outlets. However, with increasing torsion angle, the TAWSS in the iliac graft decreases and the RRT increases. In addition, our numerical simulations and in vitro experiments reveal that the displacement force increases gradually with increasing torsion angle. In summary, the “crossed limbs” strategy may have benefits for AAA treatment in terms of helical flow, but because of the unfavorable hemodynamic performance verified by analyzing the hemodynamic indicators, the risk of stent graft migration increases with increasing torsion angle. Therefore, the “crossed limbs” strategy should be carefully employed in surgical AAA treatment.
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Li Z, Yan F, Yang J, Chen Y, Xu Z, Jiang W, Yuan D. Hemodynamics and Oxygen Transport through Pararenal Aortic Aneurysm Treated with Multilayer Stent: A Numerical Study. Ann Vasc Surg 2018; 54:290-297. [PMID: 30081175 DOI: 10.1016/j.avsg.2018.05.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 05/14/2018] [Accepted: 05/28/2018] [Indexed: 02/05/2023]
Abstract
BACKGROUND As opposed to an endoluminal stent graft, a multilayer stent (MS) consists of a porous mesh, which allows for the possibility of treating pararenal aortic aneurysms (PRAAs) that involve a significant branch vessel. However, the choice of the density of the MS plays a vital role in isolating the aneurysm and allowing unobstructed blood flow in the branch vessel. METHOD In the present study, we examined 3 cases (without a stent and with single-layer and double-layer stents) via numerical simulations to explore the feasibility of the MSs used in the treatment of such aneurysms and estimate whether there is a more appropriate or optimal stent density. RESULTS With stent intervention, the velocity of blood flow in the sac decreased, but the pressure on the surface of the aneurysm did not decrease although it became more uniform. In addition, the "region of double low" (with low wall shear stress and a low Sherwood number) enlarged after stent implantation. Even with the double-layer stent, however, the flux of the branch vessel was still above normal, and we could predict that the optimal stent porosity was approximately 49.9%. CONCLUSIONS Unlike in previous studies, an MS could not be feasibly applied to high-risk PRAAs. However, an MS can induce sac thrombosis in the later stages while maintaining visceral vessel patency, and our results suggest that the optimal stent may be a 4-layer stent.
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Affiliation(s)
- Zhongyou Li
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Fei Yan
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Jingru Yang
- School of Manufacturing Science & Engineering, Sichuan University, Chengdu, China
| | - Yu Chen
- Department of Applied Mechanics, Sichuan University, Chengdu, China.
| | - Zhizhi Xu
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Wentao Jiang
- Department of Applied Mechanics, Sichuan University, Chengdu, China.
| | - Ding Yuan
- Department of Vascular Surgery of West China Hospital, Sichuan University, Chengdu, China
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Yeow SL, Leo HL. Is Multiple Overlapping Uncovered Stents Technique Suitable for Aortic Aneurysm Repair? Artif Organs 2017; 42:174-183. [DOI: 10.1111/aor.12993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/23/2017] [Accepted: 06/14/2017] [Indexed: 01/22/2023]
Affiliation(s)
- Siang Lin Yeow
- Division of Research; Singapore General Hospital; Singapore
- Biomedical Engineering; National University of Singapore; Singapore
| | - Hwa Liang Leo
- Biomedical Engineering; National University of Singapore; Singapore
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Influence of overlapping pattern of multiple overlapping uncovered stents on the local mechanical environment: A patient-specific parameter study. J Biomech 2017; 60:188-196. [PMID: 28712543 DOI: 10.1016/j.jbiomech.2017.06.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/05/2017] [Accepted: 06/25/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Multiple overlapping uncovered stents (MOUS) system has shown potentials in managing complex aortic aneurysms with side branches involvement. It promotes the development of thrombus by modulating local flow pattern that reduces the wall tension, while maintaining patency of side branches. However the modulation of local hemodynamic parameters depends on various factors that have not been assessed comprehensively. METHODS Aneurysm 3D geometry was reconstructed based on CT images. One-way fluid-structure interaction analysis was performed to quantify structural stress concentration in the wall, and changes of blood velocity, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT) and pressure in the sac due to the stent deployment. RESULTS High structural stress concentration due to stent deployment was found in the landing zone and it increased linearly with the number of stents deployed. The wall tension in the sac was unaffected by the stent deployment. Stress within the wall was insensitive to the different overlapping pattern. After one stent was deployed, the mean flow velocity in the sac reduced by 36.4%. The deployment of the 2nd stent further reduced the mean sac velocity by 10%. WSS decreased while both OSI and RRT increased after stent deployment, however pressure in the sac remained nearly unchanged. Except for the cases with complete stents struts alignment, different overlapping pattern had little effect on flow parameters. CONCLUSIONS Mechanical parameters modulated by the MOUS are insensitive to different overlapping pattern suggesting that endovascular procedure can be performed with less attention to the overlapping pattern.
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Is Multilayer Bare Stent Safe or Effective for the Treatment of Aortic Aneurysms? A Meta-analysis with Early and Mid-term Outcomes. Ann Vasc Surg 2017; 40:112-119. [DOI: 10.1016/j.avsg.2016.06.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 05/21/2016] [Accepted: 06/18/2016] [Indexed: 11/19/2022]
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26
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Nardi A, Avrahami I. Approaches for treatment of aortic arch aneurysm, a numerical study. J Biomech 2017; 50:158-165. [DOI: 10.1016/j.jbiomech.2016.11.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 10/20/2022]
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Xiong Y, Wang X, Jiang W, Tian X, Wang Q, Fan Y, Chen Y. Hemodynamics study of a multilayer stent for the treatment of aneurysms. Biomed Eng Online 2016; 15:134. [PMID: 28155682 PMCID: PMC5260060 DOI: 10.1186/s12938-016-0248-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background The changes of hemodynamics caused by the implantation of multilayer stent (MS) have significant effects for aneurysm sac. Methods Comparisons of 3D numerical models with/without a MS in an abdominal aortic aneurysm with a 90° branch vessel were numerically studied from the viewpoint of hemodynamics. Results The results showed that: (1) The flow fields and Wall Shear Stress (WSS) are changed dramatically after MS implantation. The velocity of the blood flow in aneurysm sac decreases significantly and the regions of low-WSS increase. These help thrombus formation; (2) The pressure in aneurysm slightly decreases and keeps close to the normal level of blood pressure, however the risk of aneurysm enlargement or even rupture still exists; (3) The flux and the velocity in branch artery are reduced by about half after MS implantation. Due to the implantation of MS, the changes in the flow field causes the decrease of pressure/WSS in aneurysm sac and the blood flow in branch vessel. Conclusions The implantation of MS into abdominal artery results in more low-WSS regions inside aneurysm which induces thrombus formation. The pressure is reduced slightly means the risk of aneurysm rupture exists.
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Affiliation(s)
- Yan Xiong
- School of Manufacturing Science and Engineering, Sichuan University, 610065, Chengdu, China
| | - Xuhong Wang
- Department of Applied Mechanics, Sichuan University, 610065, Chengdu, China
| | - Wentao Jiang
- Department of Applied Mechanics, Sichuan University, 610065, Chengdu, China.
| | - Xiaobao Tian
- Department of Applied Mechanics, Sichuan University, 610065, Chengdu, China
| | - Qingyuan Wang
- Department of Applied Mechanics, Sichuan University, 610065, Chengdu, China
| | - Yubo Fan
- School of Biological Science and Medical Engineering, Beihang University, 100191, Beijing, China
| | - Yu Chen
- Department of Applied Mechanics, Sichuan University, 610065, Chengdu, China.
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Ong CW, Ho P, Leo HL. Effects of Microporous Stent Graft on the Descending Aortic Aneurysm: A Patient-Specific Computational Fluid Dynamics Study. Artif Organs 2016; 40:E230-E240. [DOI: 10.1111/aor.12802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/11/2016] [Accepted: 06/06/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Chi-Wei Ong
- Department of Biomedical Engineering; National University of Singapore
| | - Pei Ho
- Department of Cardiac, Thoracic and Vascular Surgery; National University Health System; Singapore
| | - Hwa-Liang Leo
- Department of Biomedical Engineering; National University of Singapore
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Hemodynamic Study of Flow Remodeling Stent Graft for the Treatment of Highly Angulated Abdominal Aortic Aneurysm. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:3830123. [PMID: 27247612 PMCID: PMC4876205 DOI: 10.1155/2016/3830123] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/30/2016] [Accepted: 04/17/2016] [Indexed: 11/18/2022]
Abstract
This study investigates the effect of a novel flow remodeling stent graft (FRSG) on the hemodynamic characteristics in highly angulated abdominal aortic aneurysm based on computational fluid dynamics (CFD) approach. An idealized aortic aneurysm with varying aortic neck angulations was constructed and CFD simulations were performed on nonstented models and stented models with FRSG. The influence of FRSG intervention on the hemodynamic performance is analyzed and compared in terms of flow patterns, wall shear stress (WSS), and pressure distribution in the aneurysm. The findings showed that aortic neck angulations significantly influence the velocity flow field in nonstented models, with larger angulations shifting the mainstream blood flow towards the center of the aorta. By introducing FRSG treatment into the aneurysm, erratic flow recirculation pattern in the aneurysm sac diminishes while the average velocity magnitude in the aneurysm sac was reduced in the range of 39% to 53%. FRSG intervention protects the aneurysm against the impacts of high velocity concentrated flow and decreases wall shear stress by more than 50%. The simulation results highlighted that FRSG may effectively treat aneurysm with high aortic neck angulations via the mechanism of promoting thrombus formation and subsequently led to the resorption of the aneurysm.
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Xue Y, Liu X, Sun A, Zhang P, Fan Y, Deng X. Hemodynamic Performance of a New Punched Stent Strut: A Numerical Study. Artif Organs 2015; 40:669-77. [PMID: 26581476 DOI: 10.1111/aor.12638] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Local flow disturbance by arterial stent struts has been shown to play an important role in stent thrombosis. To reduce the local flow disturbance near a stent strut, we proposed a new concept of stent design with small holes in the stent struts. The present study evaluated the new design numerically by comparing it with the traditional stent in terms of local hemodynamic parameters such as flow velocity, flow recirculation area, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), and relative residence time (RRT). The results demonstrated that when compared with the traditional strut, the new design could significantly enhance flow velocity and reduce the flow recirculation zone in the vicinity of the strut. Moreover, the new design would significantly elevate TAWSS and remarkably reduce OSI and RRT along the host arterial wall. In conclusion, the new design of stent struts with punched holes is advantageous over the traditional one in the aspect of improving local hemodynamics, which may reduce thrombosis formation and promote re-endothelialization after stenting.
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Affiliation(s)
- Yan Xue
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Peng Zhang
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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