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Papadopoulos KP, Gavaises M, Pantos I, Katritsis DG, Mitroglou N. Derivation of flow related risk indices for stenosed left anterior descending coronary arteries with the use of computer simulations. Med Eng Phys 2016; 38:929-39. [DOI: 10.1016/j.medengphy.2016.05.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/15/2016] [Accepted: 05/26/2016] [Indexed: 10/21/2022]
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Schrauwen JTC, Karanasos A, van Ditzhuijzen NS, Aben JP, van der Steen AFW, Wentzel JJ, Gijsen FJH. Influence of the Accuracy of Angiography-Based Reconstructions on Velocity and Wall Shear Stress Computations in Coronary Bifurcations: A Phantom Study. PLoS One 2015; 10:e0145114. [PMID: 26690897 PMCID: PMC4686962 DOI: 10.1371/journal.pone.0145114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/28/2015] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Wall shear stress (WSS) plays a key role in the onset and progression of atherosclerosis in human coronary arteries. Especially sites with low and oscillating WSS near bifurcations have a higher propensity to develop atherosclerosis. WSS computations in coronary bifurcations can be performed in angiography-based 3D reconstructions. It is essential to evaluate how reconstruction errors influence WSS computations in mildly-diseased coronary bifurcations. In mildly-diseased lesions WSS could potentially provide more insight in plaque progression. MATERIALS METHODS Four Plexiglas phantom models of coronary bifurcations were imaged with bi-plane angiography. The lumens were segmented by two clinically experienced readers. Based on the segmentations 3D models were generated. This resulted in three models per phantom: one gold-standard from the phantom model itself, and one from each reader. Steady-state and transient simulations were performed with computational fluid dynamics to compute the WSS. A similarity index and a noninferiority test were used to compare the WSS in the phantoms and their reconstructions. The margin for this test was based on the resolution constraints of angiography. RESULTS The reconstruction errors were similar to previously reported data; in seven out of eight reconstructions less than 0.10 mm. WSS in the regions proximal and far distal of the stenosis showed a good agreement. However, the low WSS areas directly distal of the stenosis showed some disagreement between the phantoms and the readers. This was due to small deviations in the reconstruction of the stenosis that caused differences in the resulting jet, and consequently the size and location of the low WSS area. DISCUSSION This study showed that WSS can accurately be computed within angiography-based 3D reconstructions of coronary arteries with early stage atherosclerosis. Qualitatively, there was a good agreement between the phantoms and the readers. Quantitatively, the low WSS regions directly distal to the stenosis were sensitive to small reconstruction errors.
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Affiliation(s)
- Jelle T C Schrauwen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Antonios Karanasos
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
| | | | | | - Antonius F W van der Steen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Imaging Physics, Delft University of Technology, Delft, the Netherlands
| | - Jolanda J Wentzel
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Frank J H Gijsen
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, the Netherlands
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Qiao A, Zhang Z. Numerical Simulation of Vertebral Artery Stenosis Treated With Different Stents. J Biomech Eng 2014; 136:1789553. [DOI: 10.1115/1.4026229] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 12/12/2013] [Indexed: 11/08/2022]
Abstract
We sought to investigate the effects of endovascular stents with different links for treating stenotic vertebral artery and to determine the relationship between the shape of the link and in-stent restenosis (ISR). We also attempted to provide scientific guidelines for stent design and selection for clinical procedures. Models of three types of stent with different links (L-stent, V-stent, and S-stent) and an idealized stenotic vertebral artery were established. The deployment procedure for the stent in the stenotic vertebral artery was simulated for solid mechanics analysis. Next, the deformed models were extracted to construct the blood flow domain, and numerical simulations of the hemodynamics in these models were performed using the finite element method. The numerical results demonstrated that: (1) Compared with the L-stent and V-stent, the S-stent has a better flexibility and induces less stress in the stent strut. Furthermore, less stress is generated in the arterial wall. (2) Vascular straightening is scarcely influenced by the shape of the link, but it is closely related to the flexibility of the stent. (3) The S-stent has the smallest foreshortening among the three types of stents. (4) Compared with the V-stent and S-stent, the L-stent causes a smaller area with low wall shear stress, less blood stagnation area, and better blood flow close to the artery wall. From the viewpoint of the combination of solid mechanics and hemodynamics, the S-stent has better therapeutic effects because of its lower potential for inducing ISR and its better prospects in clinical applications compared with the L-stent and V-stent.
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Affiliation(s)
- Aike Qiao
- Mem. ASME College of Life Science and Bio-engineering, Beijing University of Technology, Beijing 100124, China e-mail:
| | - Zhanzhu Zhang
- College of Life Science and Bio-engineering, Beijing University of Technology, Beijing 100124, China e-mail:
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Su B, Huo Y, Kassab GS, Kabinejadian F, Kim S, Leo HL, Zhong L. Numerical investigation of blood flow in three-dimensional porcine left anterior descending artery with various stenoses. Comput Biol Med 2014; 47:130-8. [PMID: 24607680 DOI: 10.1016/j.compbiomed.2014.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 01/02/2014] [Accepted: 01/04/2014] [Indexed: 12/15/2022]
Abstract
Coronary heart disease causes obstruction of coronary blood flow and is the leading cause of death worldwide. The effect of focal stenosis on downstream flow pattern in the coronary arterial tree is not well understood. Here, the blood flows in normal and diseased porcine left anterior descending (LAD) arterial tree were modeled and compared to determine the effects of stenosis on the blood flow distribution and hemodynamic parameters. The anatomical model of LAD was extracted from a porcine heart by computed tomography (CT), which was comprised of a main trunk and nine side branches. Stenoses with various severities were imposed into the main trunk between the first and second side branches, and the boundary condition at each outlet accounted for the effect of stenosis on the flow rate in the downstream vasculature. It was found that only significant stenosis (≥75% area reduction) considerably altered pressure drop and total flow rate distribution in branches and at each bifurcation. The effect of significant stenosis on bifurcations, however, diminished at downstream locations. As demonstrated by distributions of oscillatory shear index and relative residence time, non-significant stenosis (<75% area reduction) has the potential to induce atherosclerosis near the ostium of downstream side branch, while significant stenosis can promote atherosclerosis in its wake.
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Affiliation(s)
- Boyang Su
- Research and Development Unit, National Heart Centre Singapore, 17 third hospital avenue, Mistri Wing, Singapore 168752, Singapore
| | - Yunlong Huo
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Mechanics Building 507, Beijing 10087, China
| | - Ghassan S Kassab
- School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Foad Kabinejadian
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore.
| | - Liang Zhong
- Research and Development Unit, National Heart Centre Singapore, 17 third hospital avenue, Mistri Wing, Singapore 168752, Singapore
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Ho CY, Liao HM, Tu CY, Huang CY, Shih CM, Su MYL, Chen JH, Shih TC. Numerical analysis of airflow alteration in central airways following tracheobronchial stent placement. Exp Hematol Oncol 2012; 1:23. [PMID: 23211056 PMCID: PMC3514122 DOI: 10.1186/2162-3619-1-23] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 08/14/2012] [Indexed: 11/10/2022] Open
Abstract
The computational fluid dynamics method, which provides an estimation of the pressure drop in the airway before and after the stent implantation, is proposed in this study. This method is based on the finite volume model. The pressure field was solved by the Navier-Stokes equations. The proposed methodology was evaluated in seven health people (control group) and in fourteen patients who were assigned in two groups, in which one was tracheal stenosis and the other was bronchial stenosis. The results showed that the pressure drop after tracheal stent implantation became significantly smaller. For bronchial stent implantation cases, the airway resistance improved insignificantly.
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Affiliation(s)
- Chien-Yi Ho
- Division of Chest Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, 40402, Taiwan.
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Katritsis DG, Theodorakakos A, Pantos I, Andriotis A, Efstathopoulos EP, Siontis G, Karcanias N, Redwood S, Gavaises M. Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis. Phys Med Biol 2010; 55:1395-411. [PMID: 20150685 DOI: 10.1088/0031-9155/55/5/009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow. These flow patterns are not seen in the SCS model with an identical stenosis. Post-stenotic recirculation in the presence of a 90% stenosis was evident at both the STEMI and SCS models. The presence of 90% diameter stenosis resulted in flow reduction in the LAD of 51.5% and 35.9% in the STEMI models and 37.6% in the SCS model, for a 10 mmHg pressure drop. CFD simulations in a reconstructed model of stenotic LAD segments indicate that specific anatomic characteristics create zones of vortices and flow recirculation that promote thrombus formation and potentially myocardial infarction.
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Affiliation(s)
- D G Katritsis
- Department of Cardiology, Athens Euroclinic, Athens, Greece.
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Hemodynamically driven stent strut design. Ann Biomed Eng 2009; 37:1483-94. [PMID: 19472055 DOI: 10.1007/s10439-009-9719-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 05/16/2009] [Indexed: 01/28/2023]
Abstract
Stents are deployed to physically reopen stenotic regions of arteries and to restore blood flow. However, inflammation and localized stent thrombosis remain a risk for all current commercial stent designs. Computational fluid dynamics results predict that nonstreamlined stent struts deployed at the arterial surface in contact with flowing blood, regardless of the strut height, promote the creation of proximal and distal flow conditions that are characterized by flow recirculation, low flow (shear) rates, and prolonged particle residence time. Furthermore, low shear rates yield an environment less conducive for endothelialization, while local flow recirculation zones can serve as micro-reaction chambers where procoagulant and pro-inflammatory elements from the blood and vessel wall accumulate. By merging aerodynamic theory with local hemodynamic conditions we propose a streamlined stent strut design that promotes the development of a local flow field free of recirculation zones, which is predicted to inhibit thrombosis and is more conducive for endothelialization.
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Theodorakakos A, Gavaises M, Andriotis A, Zifan A, Liatsis P, Pantos I, Efstathopoulos EP, Katritsis D. Simulation of cardiac motion on non-Newtonian, pulsating flow development in the human left anterior descending coronary artery. Phys Med Biol 2008; 53:4875-92. [DOI: 10.1088/0031-9155/53/18/002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wu W, Wang WQ, Yang DZ, Qi M. Stent expansion in curved vessel and their interactions: A finite element analysis. J Biomech 2007; 40:2580-5. [PMID: 17198706 DOI: 10.1016/j.jbiomech.2006.11.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Accepted: 11/17/2006] [Indexed: 11/16/2022]
Abstract
Coronary restenosis after angioplasty has been reduced by stenting procedure, but in-stent restenosis (ISR) has not been eliminated yet, especially in tortuous vessels. In this paper, we proposed a finite element method (FEM) to study the expansion of a stent in a curved vessel (the CV model) and their interactions. A model of the same stent in a straight vessel (the SV model) was also studied and mechanical parameters of both models were researched and compared, including final lumen area, tissue prolapse between stent struts and stress distribution. Results show that in the CV model, the vessel was straightened by stenting and a hinge effect can be observed at extremes of the stent. The maximum tissue prolapse of the CV model was more severe (0.079 mm) than the SV model (0.048 mm); and the minimum lumen area of the CV was decreased (6.10 mm(2)), compared to that of the SV model (6.28 mm(2)). Tissue stresses of the highest level were concentrated in the inner curvature of the CV model. The simulations offered some explanations for the clinical results of ISR in curved vessels and gave design suggestions of the stent and balloon for tortuous vessels. This FEM provides a tool to study mechanisms of stents in curved vessels and can improve new stent designs especially for tortuous vessels.
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Affiliation(s)
- Wei Wu
- Department of Materials Engineering, Dalian University of Technology, No. 2, LingGong Road, Dalian, LiaoNing 116024, China.
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