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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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Csonka D, Kalmár Nagy K, Szakály P, Szukits S, Bogner P, Koller A, Kun S, Wittmann I, Háber I, Horváth I. Optimal Renal Artery-Aorta Angulation Revealed by Flow Simulation. Kidney Blood Press Res 2023; 48:249-259. [PMID: 36940678 PMCID: PMC10173746 DOI: 10.1159/000530169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 03/08/2023] [Indexed: 03/22/2023] Open
Abstract
INTRODUCTION In the circulatory system, the vessel branching angle may have hemodynamic consequences. We hypothesized that there is a hemodynamically optimal range for the renal artery's branching angle. METHODS Data on the posttransplant kinetics of estimated glomerular filtration rate (eGFR) were analyzed according to the donor and implant sides (right-to-right and left-to-right position; n = 46). The renal artery branching angle from the aorta of a randomly selected population was measured using an X-ray angiogram (n = 44). Computational fluid dynamics simulation was used to elucidate the hemodynamic effects of angulation. RESULTS AND DISCUSSION Renal transplant patients receiving a right donor kidney to the right side showed faster adaptation and higher eGFR values than those receiving a left donor kidney to the right side (eGFR: 65 ± 7 vs. 56 ± 6 mL/min/1.73 m2; p < 0.01). The average branching angle on the left side was 78° and that on the right side was 66°. Simulation results showed that the pressure, volume flow, and velocity were relatively constant between 58° and 88°, indicating that this range is optimal for the kidneys. The turbulent kinetic energy does not change significantly between 58° and 78°. CONCLUSION The results suggest that there is an optimal range for the renal artery's branching angle from the aorta where hemodynamic vulnerability caused by the degree of angulation is the lowest, which should be considered during kidney transplantations.
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Affiliation(s)
- Dávid Csonka
- Department of Mechanical Engineering, Faculty of Engineering and Information Technology, University of Pécs, Pécs, Hungary
| | - Károly Kalmár Nagy
- Department of Surgery, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Szakály
- Department of Surgery, Medical School, University of Pécs, Pécs, Hungary
| | - Sándor Szukits
- Department of Diagnostics, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Bogner
- Department of Diagnostics, Medical School, University of Pécs, Pécs, Hungary
| | - Akos Koller
- Department of Morphology and Physiology, Faculty of Health Sciences, Budapest, Hungary
- Department of Translational Medicine, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Department of Physiology, New York Medical College, Valhalla, NY, USA
| | - Szilárd Kun
- 2nd Department of Medicine and Nephrology-Diabetes Center, Medical School, University of Pécs, Pécs, Hungary
| | - István Wittmann
- 2nd Department of Medicine and Nephrology-Diabetes Center, Medical School, University of Pécs, Pécs, Hungary
| | - István Háber
- Department of Mechanical Engineering, Faculty of Engineering and Information Technology, University of Pécs, Pécs, Hungary
| | - Iván Horváth
- Heart Institute, Medical School, University of Pécs, Pécs, Hungary
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Wen J, Wang J, Peng L, Yuan D, Zheng T. Hemodynamic analysis of hybrid treatment for thoracoabdominal aortic aneurysm based on Newtonian and non-Newtonian models in a patient-specific model. Comput Methods Biomech Biomed Engin 2023; 26:209-221. [PMID: 35414317 DOI: 10.1080/10255842.2022.2053683] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The accuracy of the Newtonian model used in retrograde visceral revascularization (RVR) of hybrid surgery for thoracoabdominal aortic aneurysm (TAAA) hemodynamic simulation remains unclear. Noting that an appropriate blood viscosity model is a significant factor to capture hemodynamic changes in numerical studies. Therefore, both Newtonian and non-Newtonian blood viscosity models were adopted in this study to investigate the importance of hemodynamics when non-Newtonian blood property was accounted for in a patient-specific RVR simulation. The results revealed that disturbed flow and unfavorable WSS distribution can be observed in the anastomosis region under both blood viscosity models due to the retrograde flow pattern in the RVR model. However, although the non-Newtonian blood model has negligible effect on flow pattern and pressure drop, there were of significance quantitative and qualitative difference of local normalized helicity and wall shear stress distribution under pulsatile flow condition. In particular, the unfavorable WSS indicators distribution was better matched with a patient-specific follow-up report when non-Newtonian blood viscosity was accounted for. To conclude, the use of a Newtonian blood model is a reasonable approximation to obtain the general features of the flow field under steady flow condition. However, to study the hemodynamic parameters within retrograde flow under pulsatile flow condition, a non-Newtonian model may be more appropriate.
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Affiliation(s)
- Jun Wen
- Institute of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang, China
| | - Jiarong Wang
- Department of Vascular Surgery, West China Hospital, Sichuan University, Chengdu, China
| | - Liqing Peng
- Department of Radiology, West China Hospital, Sichuan University, Chengdu, China
| | - Ding Yuan
- Department of Vascular Surgery, West China Hospital, Sichuan University, Chengdu, China
| | - Tinghui Zheng
- Department of Applied Mechanics, Sichuan University, Chengdu, China
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Zhang X, Chen D, Wu M, Dong H, Wan Z, Jia H, Liang S, Shao J, Zheng J, Xu S, Xiong J, Guo W. Functional Evaluation of Embedded Modular Single-Branched Stent Graft: Application to Type B Aortic Dissection With Aberrant Right Subclavian Artery. Front Cardiovasc Med 2022; 9:869505. [PMID: 35586645 PMCID: PMC9108238 DOI: 10.3389/fcvm.2022.869505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
Background Endovascular repair of type B aortic dissection (TBAD) with aberrant right subclavian artery (ARSA) is challenging due to anatomical complexity. The embedded modular single-branched stent graft (EMSBSG) could solve this problem. However, the hemodynamic efficacy of this innovative technique has not been fully assessed. This study aimed to propose morphometric and functional indicators to quantify the outcomes of EMSBSG in treating TBAD with ARSA. Material and Methods A patient who had TBAD with ARSA underwent EMSBSG implantation was admitted. Computational fluid dynamics (CFD) and three-dimensional structural analyses were conducted based on CTA datasets before the operation (Pre-1) and at 4 and 25 days after EMSBSG implantation (Post-1 and Post-2). Quantitative and qualitative functional analyses were conducted via pressure-, velocity- and wall shear stress (WSS) -based parameters, such as the luminal pressure difference (LPD), total energy loss, and flow distribution ratio. By precisely registering the aortas at the three time points, parameter variations in the EMSBSG region were also computed to investigate the prognostic improvement after EMSBSG implantation. Results The first balance point of LPD distally shifted to the abdominal aorta in Post-1 by a distance of 20.172 cm, and shifted out of the dissected region in Post-2, indicating positive pressure recovery post EMSBSG. The flow distribution ratios of all aortic arch branches increased after EMSBSG implantation. A positive normal deformation index in the EMSBSG region confirmed true lumen expansion; dominant ARN (area ratio of negative value) of pressure and WSS-based parameters indicated an improved prognosis from Post-1 to Post-2. Conclusions The short-term results of EMSBSG in treating TBAD with ARSA proved to be promising, especially in EMSBSG region. Comprehensive evaluation could provide new insight into the therapy of TBAD with ARSA. Thus, it might guide the further management of complex aortic arch lesions.
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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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Infrarenal versus supraceliac aorto-hepatic arterial revascularisation in adult liver transplantation: multicentre retrospective study. Updates Surg 2020; 72:659-669. [PMID: 32594369 DOI: 10.1007/s13304-020-00839-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/21/2020] [Indexed: 10/24/2022]
Abstract
When the standard arterial reconstruction is not feasible during liver transplantation (LT), aorto-hepatic arterial reconstruction (AHAR) can be the only solution to save the graft. AHAR can be performed on the infrarenal (IR) or supraceliac (SC) tract of the aorta, but the possible effect on outcome of selecting SC versus IR reconstruction is still unclear. One hundred and twenty consecutive patients who underwent liver transplantation with AHAR in six European centres between January 2003 and December 2018 were retrospectively analysed to ascertain whether the incidence of hepatic artery thrombosis (HAT) was influenced by the type of AHAR (IR-AHAR vs. SC-AHAR). In 56/120 (46.6%) cases, an IR anastomosis was performed, always using an interposition arterial conduit. In the other 64/120 (53.4%) cases, an SC anastomosis was performed; an arterial conduit was used in 45/64 (70.3%) cases. Incidence of early (≤ 30 days) HAT was in 6.2% (4/64) in the SC-AHAR and 10.7% (6/56) IR-AHAR group (p = 0.512) whilst incidence of late HAT was significantly lower in the SC-AHAR group (4.7% (3/64) vs 19.6% (11/56) - p = 0.024). IR-AHAR was the only independent risk factor for HAT (exp[B] = 3.915; 95% CI 1.400-10.951; p = 0.009). When AHAR is necessary at liver transplantation, the use of the supraceliac aorta significantly reduces the incidence of hepatic artery thrombosis and should therefore be recommended whenever possible.
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Georgiadis GS, Koutsoumpelis A, Tsilimparis N. Commentary: Physician-Modified Fenestrated/Branched EVAR and Hybrid Techniques for Acute Thoracoabdominal Aortic Pathologies: Inequality When Comparing Alternative Options With Different Philosophies Does Not Equal Lower Quality. J Endovasc Ther 2020; 27:757-763. [PMID: 32580674 DOI: 10.1177/1526602820934469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- George S Georgiadis
- Department of Vascular Surgery, "Democritus" University of Thrace, University General Hospital of Evros, Alexandroupolis, Greece
| | - Andreas Koutsoumpelis
- Department of Vascular Surgery, "Democritus" University of Thrace, University General Hospital of Evros, Alexandroupolis, Greece
| | - Nikolaos Tsilimparis
- Department of Vascular Surgery, Ludwig-Maximilians-University Hospital, Munich, Germany
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Longitudinal computational fluid dynamics study of stenosis and aneurysmal degeneration of an aortorenal bypass. Biomech Model Mechanobiol 2020; 19:1965-1975. [PMID: 32200478 DOI: 10.1007/s10237-020-01320-9] [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: 10/16/2019] [Accepted: 03/12/2020] [Indexed: 02/05/2023]
Abstract
Saphenous vein graft (SVG) bypass placement is regarded as the optimal option for renal artery stenosis, which usually causes secondary hypertension and poor renal perfusion. Using computational fluid dynamics, this study aimed to investigate the underlying hemodynamic mechanism of the vein aneurysm and stenosis after aortorenal bypass surgery. Three-dimensional models were reconstructed based on computed tomographic angiography images of a 20-year-old female patient who suffered from uncontrollable hypertension using the image processing package Mimics (Materialise). The morphology and hemodynamic parameters in the healthy state, at initial presentation and at post-operative 9-month and 2-year follow-ups after surgery were analysed. The hemodynamic parameters became normal in the left and right renal arteries after bypass surgery. However, flow separation and stagnation occurred at the post-operative 9-month aorta-vein anastomosis, which caused asymmetrical flow and extremely high wall shear stress (WSS) and WSS gradients at the outflow vein tract, where the stenosis occurred 2 years later. In addition, the graft bending produced an asymmetrical flow pattern downstream. This research revealed that the abnormal hemodynamics, including flow separation and extremely high WSS values and gradients, caused by the retrograde flow of aortorenal bypass may be responsible for the SVG degeneration. In addition, flow asymmetry due to vessel bending is a potential risk factor for SVG aneurysm dilation.
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Comparison of Hybrid Vascular Grafts and Standard Grafts in Terms of Kidney Injury for the Treatment of Thoraco-Abdominal Aortic Aneurysm. World J Surg 2020; 44:2010-2019. [DOI: 10.1007/s00268-020-05415-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Numerical simulation of haemodynamics of the descending aorta in the non-diabetic and diabetic rabbits. J Biomech 2019; 91:140-150. [DOI: 10.1016/j.jbiomech.2019.05.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 05/06/2019] [Accepted: 05/13/2019] [Indexed: 12/12/2022]
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Yuan D, Wen J, Peng L, Zhao J, Zheng T. Precise plan of hybrid treatment for thoracoabdominal aortic aneurysm: Hemodynamics of retrograde reconstruction visceral arteries from the iliac artery. PLoS One 2018; 13:e0205679. [PMID: 30321207 PMCID: PMC6188790 DOI: 10.1371/journal.pone.0205679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/29/2018] [Indexed: 02/05/2023] Open
Abstract
Hybrid visceral-renal debranching procedures with endovascular repair have been proposed as a less invasive alternative to conventional thoracoabdominal aortic aneurysm or dissection (TAAA or TAAD) surgery. Up to now, there has been no information about the hemodynamic effects of retrograde visceral reconstruction (RVR) for Crawford type II/III/IV TAAA patients undergoing hybrid treatment. The aim is to provide insights in the abnormal hemodynamics of RVR from unilateral or bilateral common iliac arteries (CIAs). Idealized three-dimensional AAs with RVR from unilateral CIA or bilateral CIAs were generated and computationally simulated. The results show that RVRs from CIA lead to a dramatic decrease in flow to the visceral organs compared with a healthy AA and that the anastomosis region is most dangerous to graft occlusion and the initiation of an aneurysm. In addition, compared with a quar-furcated graft, the employment of bilateral bi-furcated grafts have better performance in terms of the wall shear stress (WSS) and flow filed but result in less flow to the celiac and mesenteric arteries. This study has revealed the potential risks after an RVR operation, and points out the advantages and disadvantages of different approaches for the visceral reconstruction, which the vascular surgeons are not fully aware of. According to our results, bilateral bi-furcated grafts are recommended to the TAAA patients when the CIAs are unique inflow sites for visceral reconstruction. A precise plan with patient specific for TAAA or TAAD will be designed for better long-term outcome.
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Affiliation(s)
- Ding Yuan
- Department vascular surgery of West China Hospital, Sichuan University, Chengdu, China
| | - Jun Wen
- School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang, Sichuan,China
| | - Liqing Peng
- Department of Radiology, West China Hospital, Sichuan University, Chengdu, China
| | - Jichun Zhao
- Department vascular surgery of West China Hospital, Sichuan University, Chengdu, China
| | - Tinghui Zheng
- Department of Applied Mechanics, Sichuan University, Chengdu, China
- * E-mail:
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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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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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