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Hemodynamic Impact of Stenting on Carotid Bifurcation: A Potential Role of the Stented Segment and External Carotid Artery. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:7604532. [PMID: 34868344 PMCID: PMC8642019 DOI: 10.1155/2021/7604532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 10/26/2021] [Accepted: 11/05/2021] [Indexed: 11/30/2022]
Abstract
Carotid stenting near the bifurcation carina is associated with adverse events, especially in-stent restenosis, thrombosis, and side branch occlusion in clinical data. This study is aimed at determining the potential biomechanical mechanisms for these adverse events after carotid stenting. The patient-specific carotid models were constructed with different stenting scenarios to study the flow distribution and hemodynamic parameters, such as wall shear stress (WSS), flow velocity, relative residence time (RRT), and oscillating shear index (OSI) in the carotid bifurcation. The results suggested that the existing stents surely reduced blood flow to the external carotid artery (ECA) but enhanced local flow disturbance both in ECA and stented internal carotid artery (ICA), and the inner posterior wall of the stented ICA and the outer posterior wall of ECA might endure a relatively low level of WSS and remarkably elevated OSI and RRT. In addition, the implanted stent leads to more ECA adverse flow than ICA after stenting. While disturbed flow near the strut increased as stent length increased, blood flow and areas of local flow disturbance in ECA slightly decreased as stent length increased. In conclusion, the results revealed that ECA might be in relatively high levels of abnormal local hemodynamics after stenting, followed by stented ICA, leading to potential adverse events after intervention.
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Bai H, Wei S, Xie B, Wang Z, Li M, Qiao Z, Sun P, Wang W. Endothelial nitric oxide synthase (eNOS) mediates neointimal thickness in arteriovenous fistulae with different anastomotic angles in rats. J Vasc Access 2021; 23:403-411. [PMID: 33619996 DOI: 10.1177/1129729821996537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND It is known that the anastomotic angle can influence neointimal hyperplasia and patency in arteriovenous fistulae (AVF). Endothelial nitric oxide synthase (eNOS) is released from the vascular endothelium and can inhibit neointimal hyperplasia. Therefore, here, we aimed to test the hypothesis that the manipulation of eNOS expression could influence neointimal thickness in a rat AVF model with different anastomosis angles. METHODS Rat carotid artery (inflow, CA) and jugular vein (outflow, JV) AVF were created with acute, blunt, or end-to-end (ETE) anastomosis angles. Aspirin was used to increase eNOS expression in the acute angle group, while N(G)-nitro-L-arginine methyl ester (L-name) was used to decrease eNOS expression in the obtuse angle group. The rats were sacrificed on day 21, and tissues were harvested and analyzed histologically and with immunostaining. RESULTS A larger anastomosis diameter (p < 0.016) and smaller neointimal area (p < 0.01) were observed in the obtuse and end-to-end (ETE) groups compared to in the acute group. In the acute angle group, there were more proliferating cell nuclear antigen (PCNA) and α-actin dual-positive cells (p < 0.0001) and fewer phospho (p)-eNOS-positive endothelial cells (p < 0.0001) in the neointima than in the obtuse and ETE angle groups. On treating the acute angle and blunt angle groups with aspirin and L-name, respectively, no significant differences in the neointima/lumen rate were observed (p = 0.6526) between the groups; however, there were fewer von Willebrand factor (vWF) and p-eNOS dual-positive cells in the obtuse angle group treated with L-name (p = 0.0045). CONCLUSIONS We demonstrated that eNOS plays an important role in neointimal hyperplasia in AVF with different anastomosis angles; further, eNOS could potentially be used as a therapeutic target in patients with AVF in the future.
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Affiliation(s)
- Hualong Bai
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.,Key Vascular Physiology and Applied Research Laboratory of Zhengzhou City, Henan, China
| | - Shunbo Wei
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Boao Xie
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Zhiwei Wang
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Mingxing Li
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Zhentao Qiao
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Peng Sun
- Department of Vascular and Endovascular Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Wang Wang
- Department of Physiology, Medical school of Zhengzhou University, Zhengzhou, Henan, China.,Key Vascular Physiology and Applied Research Laboratory of Zhengzhou City, Henan, China
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Zhu L, Pan Z, Li Z, Chang Y, Zhu Y, Yan F, Tu S, Yang W. Can the Wall Shear Stress Values of Left Internal Mammary Artery Grafts during the Perioperative Period Reflect the One-Year Patency? Thorac Cardiovasc Surg 2020; 68:723-729. [PMID: 32937666 DOI: 10.1055/s-0040-1714385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE The left internal mammary artery (LIMA) is the preferred graft for coronary artery bypass grafting, but the reasoning for LIMA occlusion is unclear. We sought to examine whether the wall shear stress (WSS) values of LIMA grafts during the perioperative period reflected the 1-year patency by using combining computational fluid dynamics (CFD) and coronary computed tomography angiography (CCTA) images. METHODS CCTA was performed in 233 patients with LIMA graft perioperatively and 1 year later from October 2014 to May 2017. LIMA occlusion was detected in six patients at the 1-year follow-up CCTA. Two patients were excluded due to poor imaging quality. The remaining four patients were enrolled as occlusive (OCC) group, and eight patients with patent LIMA were recruited as patent (PAT) group. The WSS values of LIMA during perioperative period were calculated. LIMA graft was artificially divided into three even segments, proximal (pLIMA), middle (mLIMA) and distal (dLIMA) segments. The independent samples t-test and the Student-Newman-Keuls test were used. RESULTS The WSS values of dLIMA were significantly higher in the PAT group than in the OCC group (4.43 vs. 2.56, p < 0.05). The WSS values of dLIMA in the PAT group were significantly higher than pLIMA, which was absent in the OCC group. CONCLUSIONS A higher WSS value of the distal segment of LIMA and a higher WSS value of the distal segment compared with the proximal segment of LIMA in the PAT were observed; this tendency might be helpful in predicting the 1-year patency of LIMA.
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Affiliation(s)
- Lan Zhu
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zilai Pan
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zehang Li
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yunxiao Chang
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yunpeng Zhu
- Department of Cardiac Surgery, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fuhua Yan
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shengxian Tu
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Wenjie Yang
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Arefin MS. Hemodynamic and structural effects on bypass graft for different levels of stenosis using fluid structure interaction: A prospective analysis. JOURNAL OF VASCULAR NURSING 2019; 37:169-187. [PMID: 31727309 DOI: 10.1016/j.jvn.2019.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/15/2019] [Accepted: 05/20/2019] [Indexed: 10/26/2022]
Abstract
Although the flow dynamics have been investigated using fluid-structure interaction scheme for the internal thoracic artery-left anterior descending coronary artery (ITA-LAD) bypass graft in different cases, a detailed analysis associating different degrees of LAD stenosis and its effects on hemodynamics and structural displacement are not comprehensively studied. Therefore, the primary focus of this work is to examine and determine the correlation between the hemodynamic effects and structural variations inside the bypass graft with different degrees of LAD stenosis (0%, 30%, 50%, and 75%). Navier-Stokes equation, arbitrary Lagrangian-Eulerian, and elasticity in the solid region are implemented by coupling incompressible viscous fluid, nonlinear viscous fluid, and the stress tensor equations, respectively. Using fluid-structure interaction, variations in the hemodynamic property and changes in wall shear stress (WSS) including the spatial WSS distribution and the changes in the displacement of different degree of LAD stenosis are determined.Maximum WSS is found to be around 1.58E1 Pa near the anastomosis region and maximum magnitude for the structural displacement is found to be approximately 1.25E-5 m close to the heel. The results demonstrate that the disturbance in the flow pattern is evident mainly in the anastomosis region. Consequently, higher WSS is observed near the toe and on the artery wall, near the anastomosis region.
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Affiliation(s)
- Md Shamsul Arefin
- FSET, Swinburne University of Technology, Hawthorn, Victoria, Australia.
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Transfer of Low-Density Lipoproteins in Coronary Artery Bifurcation Lesions with Stenosed Side Branch: Numerical Study. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:5297284. [PMID: 31737085 PMCID: PMC6815532 DOI: 10.1155/2019/5297284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/08/2019] [Accepted: 08/04/2019] [Indexed: 11/17/2022]
Abstract
Evidence from clinical data suggests that the stenotic side branch (SB) is one of the key predictors for SB occlusion-based adverse events. In this study, we hypothesized that coronary bifurcations with stenotic SB might lead to severe concentration polarization of atherogenic lipids, such as the low-density lipoproteins (LDL), motivating the adverse events in the clinic. To confirm this hypothesis, this work numerically investigated the transport of LDL in different bifurcation lesions based on the Medina classification with various location and stenosis severities. The results showed that the coronary bifurcations with stenotic SB might be suffering more serious concentration polarization of LDL on the luminal surface of the SB due to higher level of LDL concentrations. Moreover, compared to the other bifurcation lesion types, the type (1,0,1) had the highest luminal surface LDL concentration along the SB and the highest degree of risk to enhance the process of atherosclerosis. In addition, this study also showed that the luminal surface LDL concentration increased with elevated stenosis severity. The type (1,0,1) with the severe stenosis (75% diameter reduction) had the highest concentration at the SB. In conclusion, these results suggested that both location of lesions and stenosis severities had great influence on the distribution of LDL on the luminal surface of the SB. Therefore, the estimation of disease severity and the interventional therapy should be carried out not only according to the stenosis severities in clinic. Moreover, compared to the other bifurcation lesion types, the type (1,0,1), rather than the type (1,1,1) as usually considered, had the highest luminal surface LDL concentration along the SB and the highest degree of risk to enhance the process of atherosclerosis.
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MISRA JC, CHANDRA S. EFFECT OF COUPLE STRESSES ON ELECTROKINETIC OSCILLATORY FLOW OF BLOOD IN THE MICROCIRCULATORY SYSTEM. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519418500355] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Of concern in the paper is the development of a mathematical model of blood flow in the microcirculatory system. The study pertains to a situation, where the system is subject to the action of an external AC electric field and the flow is oscillatory. The general case when the frequency of the electric field is different from that of the flow has been studied. Blood is treated as a couple stress fluid. The flow is supposed to take place between two oscillatory plates and is considered to be of electro-osmotic type. Our study is aimed at examining the effect of couple stress at different frequencies of the capillary wall and the applied AC electric field on electroosmotic flow of blood. The computational results indicate very clearly that the electrokinetic velocity of blood reduces as the couple stress effect increases and that the velocity reduces, when the Reynolds number rises. The results of the present study will serve as a reasonably good estimate for electro-osmotic transport of blood in small blood vessels.
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Affiliation(s)
- J. C. MISRA
- Centre for Healthcare Science and Technology, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India
| | - S. CHANDRA
- Department of Physics, Sabang S. K. Mahavidyalaya, Vidyasagar University, Midnapore, India
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Pakravan HA, Saidi MS, Firoozabadi B. A multiscale approach for determining the morphology of endothelial cells at a coronary artery. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33. [PMID: 28445003 DOI: 10.1002/cnm.2891] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 04/11/2017] [Accepted: 04/23/2017] [Indexed: 06/07/2023]
Abstract
The morphology of endothelial cells (ECs) may be an indication for determining atheroprone sites. Until now, there has been no clinical imaging technique to visualize the morphology of ECs in the arteries. The present study introduces a computational technique for determining the morphology of ECs. This technique is a multiscale simulation consisting of the artery scale and the cell scale. The artery scale is a fluid-structure interaction simulation. The input for the artery scale is the geometry of the coronary artery, that is, the dynamic curvature of the artery due to the cardiac motion, blood flow, blood pressure, heart rate, and the mechanical properties of the blood and the arterial wall, the measurements of which can be obtained for a specific patient. The results of the artery scale are wall shear stress (WSS) and cyclic strains as the mechanical stimuli of ECs. The cell scale is an inventive mass-and-spring model that is able to determine the morphological response of ECs to any combination of mechanical stimuli. The results of the multiscale simulation show the morphology of ECs at different locations of the coronary artery. The results indicate that the atheroprone sites have at least 1 of 3 factors: low time-averaged WSS, high angle of WSS, and high longitudinal strain. The most probable sites for atherosclerosis are located at the bifurcation region and lie on the myocardial side of the artery. The results also indicated that a higher dynamic curvature is a negative factor and a higher pulse pressure is a positive factor for protection against atherosclerosis.
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Affiliation(s)
- Hossein Ali Pakravan
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
- Department of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | - Mohammad Said Saidi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Bahar Firoozabadi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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Numerical modeling of hemodynamics scenarios of patient-specific coronary artery bypass grafts. Biomech Model Mechanobiol 2017; 16:1373-1399. [DOI: 10.1007/s10237-017-0893-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/27/2017] [Indexed: 11/26/2022]
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Wang Y, Qiu J, Luo S, Xie X, Zheng Y, Zhang K, Ye Z, Liu W, Gregersen H, Wang G. High shear stress induces atherosclerotic vulnerable plaque formation through angiogenesis. Regen Biomater 2016; 3:257-67. [PMID: 27482467 PMCID: PMC4966293 DOI: 10.1093/rb/rbw021] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/15/2016] [Accepted: 05/19/2016] [Indexed: 12/12/2022] Open
Abstract
Rupture of atherosclerotic plaques causing thrombosis is the main cause of acute coronary syndrome and ischemic strokes. Inhibition of thrombosis is one of the important tasks developing biomedical materials such as intravascular stents and vascular grafts. Shear stress (SS) influences the formation and development of atherosclerosis. The current review focuses on the vulnerable plaques observed in the high shear stress (HSS) regions, which localizes at the proximal region of the plaque intruding into the lumen. The vascular outward remodelling occurs in the HSS region for vascular compensation and that angiogenesis is a critical factor for HSS which induces atherosclerotic vulnerable plaque formation. These results greatly challenge the established belief that low shear stress is important for expansive remodelling, which provides a new perspective for preventing the transition of stable plaques to high-risk atherosclerotic lesions.
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Affiliation(s)
- Yi Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Juhui Qiu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Shisui Luo
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Xiang Xie
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Yiming Zheng
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Kang Zhang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Zhiyi Ye
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Wanqian Liu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Hans Gregersen
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
| | - Guixue Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China; Taiji Group Co, Ltd, Chongqing, 401147, China
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XIE XINZHOU, ZHENG MINWEN, DUAN XU, XIE SONGYUN, WANG YUANYUAN. DIRECT CORONARY COUPLING APPROACH FOR COMPUTING FFRCT. J MECH MED BIOL 2016. [DOI: 10.1142/s0219519417500439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
With the advances in computational fluid dynamics (CFD) and image-based modeling techniques, fractional flow reserve (FFR) can be computed from coronary computed tomography angiography (CTA) scans (FFRCT). However, this non-invasive approach requires large-scale computational resources, which limits its application in routine clinical setting. A 3D–0D coupling approach is proposed to improve the coupling efficiency of FFRCT. Aortic–root is modeled by a lumped parameter model and connected with the models of left ventricle and systemic circulation. With this approach, the interested coronary regions can be directly coupled to the lumped parameter model, resulting in a significant reduction (up to 20 times reduction) in the volume of the CFD computing domain. The proposed approach is applied to a patient-specific model and compared with previous non-reduced approach. Results show that the computed coronary flow rates, pressure waveforms and FFRCT contours by the proposed approach are consistent well with that of the non-reduced approach. These results demonstrate that the proposed approach can reduce the CFD computing domain of FFRCT significantly while maintaining the similar accuracy as compared with the non-reduced approach, and it can be further employed to promote FFRCT in routine clinical setting.
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Affiliation(s)
- XINZHOU XIE
- Department of Electronic Science and Technology, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an, Shaanxi, P. R. China
| | - MINWEN ZHENG
- Department of Radiology, Xijing Hospital, 127# West Changle Road, Xi’an, Shaanxi, P. R. China
| | - XU DUAN
- Department of Electronic Science and Technology, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an, Shaanxi, P. R. China
| | - SONGYUN XIE
- Department of Electronic Science and Technology, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an, Shaanxi, P. R. China
| | - YUANYUAN WANG
- Department of Electronic Engineering, Fudan University, 220 Handan Rd.,Yangpu District, Shanghai, P. R. China
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Longer coronary anastomosis provides lower energy loss in coronary artery bypass grafting. Heart Vessels 2016; 32:83-89. [DOI: 10.1007/s00380-016-0880-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/22/2016] [Indexed: 10/21/2022]
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Doost SN, Zhong L, Su B, Morsi YS. The numerical analysis of non-Newtonian blood flow in human patient-specific left ventricle. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2016; 127:232-247. [PMID: 26849955 DOI: 10.1016/j.cmpb.2015.12.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 12/21/2015] [Indexed: 06/05/2023]
Abstract
Recently, various non-invasive tools such as the magnetic resonance image (MRI), ultrasound imaging (USI), computed tomography (CT), and the computational fluid dynamics (CFD) have been widely utilized to enhance our current understanding of the physiological parameters that affect the initiation and the progression of the cardiovascular diseases (CVDs) associated with heart failure (HF). In particular, the hemodynamics of left ventricle (LV) has attracted the attention of the researchers due to its significant role in the heart functionality. In this study, CFD owing its capability of predicting detailed flow field was adopted to model the blood flow in images-based patient-specific LV over cardiac cycle. In most published studies, the blood is modeled as Newtonian that is not entirely accurate as the blood viscosity varies with the shear rate in non-linear manner. In this paper, we studied the effect of Newtonian assumption on the degree of accuracy of intraventricular hemodynamics. In doing so, various non-Newtonian models and Newtonian model are used in the analysis of the intraventricular flow and the viscosity of the blood. Initially, we used the cardiac MRI images to reconstruct the time-resolved geometry of the patient-specific LV. After the unstructured mesh generation, the simulations were conducted in the CFD commercial solver FLUENT to analyze the intraventricular hemodynamic parameters. The findings indicate that the Newtonian assumption cannot adequately simulate the flow dynamic within the LV over the cardiac cycle, which can be attributed to the pulsatile and recirculation nature of the flow and the low blood shear rate.
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Affiliation(s)
- Siamak N Doost
- Biomechanical and Tissue Engineering Lab, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Australia.
| | - Liang Zhong
- Duke-NUS Graduate Medical School, Singapore; National Heart Research Institute of Singapore, National Heart Centre, Singapore.
| | - Boyang Su
- National Heart Research Institute of Singapore, National Heart Centre, Singapore
| | - Yosry S Morsi
- Biomechanical and Tissue Engineering Lab, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Australia
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BATTISTA CHRISTINA, BIA DANIEL, GERMÁN YANINAZÓCALO, ARMENTANO RICARDOL, HAIDER MANSOORA, OLUFSEN METTES. WAVE PROPAGATION IN A 1D FLUID DYNAMICS MODEL USING PRESSURE-AREA MEASUREMENTS FROM OVINE ARTERIES. J MECH MED BIOL 2016. [DOI: 10.1142/s021951941650007x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study considers a 1D fluid dynamics arterial network model with 14 vessels developed to assimilate ex vivo 0D temporal data for pressure-area dynamics in individual vessel segments from 11 male Merino sheep. A 0D model was used to estimate vessel wall parameters in a two-parameter elastic model and a four-parameter Kelvin viscoelastic model. This was done using nonlinear optimization minimizing the least squares error between model predictions and measured cross-sectional areas. Subsequently, estimated values for elastic stiffness and unstressed area were related to construct a nonlinear relationship. This relation was used in the network model. A 1D single vessel model of the aorta was then developed and used to estimate the inflow profile and parameters for total resistance and compliance for the downstream network and to demonstrate effects of incorporating viscoelasticity in the arterial wall. Lastly, the extent to which vessel wall parameters estimated from ex vivo data can be used to realistically simulate pressure and area in a vessel network was evaluated. Elastic wall parameters in the network simulations were found to yield pressure-area relationships across all vessel locations and sheep that were in ranges comparable to those in the ex vivo data.
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Affiliation(s)
- CHRISTINA BATTISTA
- Department of Mathematics, North Carolina State University, 2311 Stinson Drive Raleigh, North Carolina 27695, USA
| | - DANIEL BIA
- Department of Physiology, Universidad de la Republica, Montevideo, Uruguay
| | | | | | - MANSOOR A. HAIDER
- Department of Mathematics, North Carolina State University, 2311 Stinson Drive Raleigh, North Carolina 27695, USA
| | - METTE S. OLUFSEN
- Department of Mathematics, North Carolina State University, 2311 Stinson Drive Raleigh, North Carolina 27695, USA
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PAKRAVAN HOSSEINALI, SAIDI MOHAMMADSAID, FIROOZABADI BAHAR. FSI SIMULATION OF A HEALTHY CORONARY BIFURCATION FOR STUDYING THE MECHANICAL STIMULI OF ENDOTHELIAL CELLS UNDER DIFFERENT PHYSIOLOGICAL CONDITIONS. J MECH MED BIOL 2015. [DOI: 10.1142/s021951941550089x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Atherosclerosis is a world-spread and well-known disease. This disease strongly relates to the endothelial cells (ECs) function. Normally, the endothelial cells align in the flow direction in the atheroprotected sites; however, in the case of atheroprone sites these cells orient randomly. The mechanical stimuli such as wall shear stress and strains could determine the morphology and function of the endothelial cells. In the present study, we numerically simulated the left main coronary artery (LCA) and its branches to left anterior descending (LAD) and left circumflex coronary (LCX) artery using fluid–structure interaction (FSI) modeling. The results were presented as longitudinal and circumferential strains of ECs as well as wall shear stress. Wide ranges of heart rate, cardiac motion, systolic and diastolic pressures were considered and their effects on mechanical stimuli were described in detail. The results showed that these factors could greatly influence the risk of atherosclerosis and the location of atherosclerotic lesions.
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Affiliation(s)
- HOSSEIN ALI PAKRAVAN
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - MOHAMMAD SAID SAIDI
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - BAHAR FIROOZABADI
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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JIN JINGXU, ZHANG JUNYUAN, SONG XUEWEI, HU HAO, SUN XIAOYAN, GAO ZHENHAI. EFFECT OF CEREBROSPINAL FLUID MODELED WITH DIFFERENT MATERIAL PROPERTIES ON A HUMAN FINITE ELEMENT HEAD MODEL. J MECH MED BIOL 2015. [DOI: 10.1142/s021951941550027x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this study was to enhance head-injury prediction, this paper investigated the behavior of cerebrospinal fluid (CSF) in finite element (FE) modeling. Nine different material properties selected according to material definitions and property values were used to represent CSF in FE head models. To evaluate the influence of CSF material parameters on brain mechanical responses, the models were validated against available cadaver experiment data. Results showed that coup pressure increased whereas contrecoup pressure decreased when the head sustained purely translational impact with increased bulk modulus when CSF was modeled as fluid. However, with increased bulk modulus, coup pressure, contrecoup pressure and relative skull-brain motions decreased under rotational impact. When CSF was assumed to be an elastic material, coup pressure increased whereas contrecoup pressure decreased with increased elastic modulus when the head was subjected to purely translational impact. However, the variation trend was not obvious during head rotation. Results also indicated that when subjected to brain strain and von Mises stress, the model was prone to underestimate brain injury when CSF was modeled as an elastic material, especially during purely translational impact to the head. The model with CSF as fluid reduced the strain rate of brain, which was more likely to be realistic than the model with CSF as a viscoelastic material. These findings suggested that significantly higher values of the bulk modulus of CSF modeled as fluid were needed to predict intracranial dynamic responses and brain injury during head impact.
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Affiliation(s)
- JING-XU JIN
- State Key Laboratory of Automobile Dynamic Simulation, Department of Autobody Engineering, Jilin University, Changchun 130025, P. R. China
| | - JUN-YUAN ZHANG
- State Key Laboratory of Automobile Dynamic Simulation, Department of Autobody Engineering, Jilin University, Changchun 130025, P. R. China
| | - XUE-WEI SONG
- State Key Laboratory of Automobile Dynamic Simulation, Department of Autobody Engineering, Jilin University, Changchun 130025, P. R. China
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, P. R. China
| | - HAO HU
- State Key Laboratory of Automobile Dynamic Simulation, Department of Autobody Engineering, Jilin University, Changchun 130025, P. R. China
| | - XIAO-YAN SUN
- Department of Radiology, First Clinical Hospital of Jilin University, Changchun 130012, P. R. China
| | - ZHEN-HAI GAO
- State Key Laboratory of Automobile Dynamic Simulation, Department of Autobody Engineering, Jilin University, Changchun 130025, P. R. China
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Novel modular anastomotic valve device for hemodialysis vascular access: preliminary computational hemodynamic assessment. J Vasc Access 2014; 15:448-60. [PMID: 25198822 DOI: 10.5301/jva.5000284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2014] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Arteriovenous graft patency is limited by terminal occlusion caused by intimal hyperplasia (IH). Motivated by evidence that flow disturbances promote IH progression, a modular anastomotic valve device (MAVD) was designed to isolate the graft from the circulation between dialysis periods (closed position) and enable vascular access during dialysis (open position). The objective of this study was to perform a preliminary computational assessment of the device ability to normalize venous flow between dialysis periods and potentially limit IH development and thrombogenesis. METHODS Computational fluid dynamics simulations were performed to compare flow and wall shear stress (WSS) in a native vein and MAVD prototypes featuring anastomotic angles of 90° and 30°. Low WSS (LWSS) regions prone to IH development were characterized in terms of temporal shear magnitude (TSM), oscillatory shear index (OSI), and relative residence time (RRT). Thrombogenic potential was assessed by investigating the loading history of fluid particles traveling through the device. RESULTS The closed MAVD exhibited the same flow characteristics as the native vein (0.3% difference in pressure drop, 3.5% difference in surface-averaged WSS). The open MAVD generated five LWSS regions (TSM <0.5 Pa) exhibiting different degrees of flow reversal (surface-averaged OSI: 0.03-0.36) and stagnation (max RRT: 2.50-37.16). Reduction in anastomotic angle resulted in the suppression of three LWSS regions and overall reductions in flow reversal (surface-averaged OSI <0.21) and stagnation (max RRT <18.05). CONCLUSIONS This study suggests the ability of the MAVD to normalize venous flow between dialysis periods while generating the typical hemodynamics of end-to-side vein-graft anastomoses during dialysis.
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ZHAO XI, LIU YOUJUN, DING JINLI, BAI FAN, REN XIAOCHEN, MA LIANCAI, XIE JINSHENG, ZHANG HAO. NUMERICAL STUDY OF BIDIRECTIONAL GLENN WITH UNILATERAL PULMONARY ARTERY STENOSIS. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Purpose: Hypoplastic left heart syndrome (HLHS) is a congenital heart disease and is usually associated with pulmonary artery stenosis. The superior vena cava-to-pulmonary artery (bidirectional Glenn) shunt is used primarily as a staging procedure to the total cava-to-pulmonary connection for single-ventricle complex. When HLHS coexists with pulmonary artery stenosis, the surgeons then face a multiple problem. This leads to high demand of optimized structure of Glenn surgery. The objective of this article is to investigate the influence of various anastomotic structures and the direction of superior vena cava (SVC) in Glenn on hemodynamics under pulse inflow conditions and try to find an optimal structure of SVC in Glenn surgery with unilateral pulmonary artery stenosis.Method: First, 3D patient-specific models were constructed from medical images of a HLHS patient before any surgery by using the commercial software Mimics, and another software Free-form was used to deform the reconstructed models in the computer. Four 3D patient-specific Glenn models were constructed: model-1 (normal Glenn), model-2 (lean the SVC back to the stenotic pulmonary artery), model-3 (lean the SVC towards the stenotic pulmonary artery), model-4 (add patch at junction of the SVC toward stenosis at pulmonary artery). Second, a lumped parameter model (LPM) was established to predict boundary conditions for computational fluid dynamics (CFD). In addition, numerical simulations were conducted using CFD through the finite volume method. Finally, hemodynamic parameters were obtained and evaluated.Results: It was showed that model-4 have relatively balanced vena cava blood perfusion into the left pulmonary artery (LPA) and right pulmonary artery (RPA), this may be due to less helical flow and the patch at junction of the SVC. Near stenosis of pulmonary artery, model-4 performed with the higher wall shear stress (WSS), which would benefit endothelial cell function and gene expression. In addition, results showed that model-4 performed with the lower oscillatory shear index (OSI) and wall shear stress gradient (WSSG), which would decrease the opportunity of vascular intimal hyperplasia.Conclusion: It is benefited that surgeons adds patch at junction of the SVC towards stenosis at pulmonary artery. These results can impact the surgical design and planning of the Glenn surgery with unilateral pulmonary artery stenosis.
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Affiliation(s)
- XI ZHAO
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China 100124, P. R. China
| | - YOUJUN LIU
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China 100124, P. R. China
| | - JINLI DING
- Department of Diagnostic Radiology, Beijing You An Hospital, Capital Medical University 100069, Beijing 100124, P. R. China
| | - FAN BAI
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China 100124, P. R. China
| | - XIAOCHEN REN
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China 100124, P. R. China
| | - LIANCAI MA
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China 100124, P. R. China
| | - JINSHENG XIE
- Beijing An Zhen Hospital Affiliated to Capital Medical University, No. 2 Anzhen Road Chaoyang District, Beijing, P. R. China 100029, P. R. China
| | - HAO ZHANG
- Beijing Fuwai Hospital CAMS&PUMC, No. 167 Beilishi Road Xicheng District, Beijing, P. R. China 100037, P. R. China
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DO HUNG, OWIDA AMALA, MORSI YOSRYS. INTIMAL HYPERPLASIA AND WALL SHEAR IN ARTERIAL BYPASS Y-GRAFTING AND CONSEQUENCE GRAFTING: A NUMERICAL STUDY. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500444] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The progression of intimal hyperplasia is considered to be the main cause of bypass failure and is directly related to the individual blood rheology, local arterial geometry and placement of the junctions, graft diameter and graft surface characteristics as well as the degree of compliance. In this paper we use commercial computational fluid dynamics (CFD) ANSYS to examine under the correct physiological flow conditions the hemodynamic forces of composite bypass with internal mammary artery in Y-grafting and consequence grafting which is known to achieve high patency rate and highly recommended by clinicians. Particular emphasis is given here on the parameters that could initiate the development of intimal hyperplasia within these bypass configurations. The hemodynamic flow patterns between the consequence grafting and the composite Y-grafting are observed here to be different. Moreover, on both end-to-side and side-to-side configurations, the circulating flows are detected in the vicinity of the junction area, while the Dean flow vortexes are only observed on the end-to-side configuration. Likewise, the hemodynamic flow on the end-to-side configuration on the LCX of both 45° and 90° Y-grafting is found to be smoother than that of the junction on the LCA, regardless of the changing of anastomosis angles. The high WSS gradients are observed at the vicinity of the toe and on the bed of the junction, while the low WSS are presented at the distal of the stenosis and at the stagnation point. The clinical relevance of the results are presented and discussed with particular focus on the factors and the flow patterns that trigger the development of intimal hyperplasia.
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Affiliation(s)
- HUNG DO
- Biomechanical and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, Australia
| | - AMAL A. OWIDA
- Biomechanical and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, Australia
| | - YOSRY S. MORSI
- Biomechanical and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, Australia
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Arefin MS, Morsi YS. Fluid structure interaction (FSI) simulation of the left ventricle (LV) during the early filling wave (E-wave), diastasis and atrial contraction wave (A-wave). AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:413-23. [PMID: 24570150 DOI: 10.1007/s13246-014-0250-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 01/30/2014] [Indexed: 12/01/2022]
Abstract
In this paper, the hemodynamic characteristics inside a physiologically correct three-dimensional LV model using fluid structure interaction scheme are examined under various heart beat conditions during early filling wave (E-wave), diastasis and atrial contraction wave (A-wave). The time dependent and incompressible viscous fluid, nonlinear viscous fluid and the stress tensor equations are coupled with the full Navier-Stoke's equations together with the Arbitrary Lagrangian-Eulerian and elasticity in the solid domain are used in the analysis. The results are discussed in terms of the variation in the intraventricular pressure, wall shear stress (WSS) and the fluid flow patterns inside the LV model. Moreover, changes in the magnitude of displacements on the LV are also observed during diastole period. The results obtained demonstrate that the magnitude of the intraventricle pressure is found higher in the basal region of the LV during the beginning of the E-wave and A-wave, whereas the Ip is found much higher in the apical region when the flow propagation is in peak E-wave, peak A-wave and diastasis. The magnitude of the pressure is found to be 5.4E2 Pa during the peak E-wave. Additionally, WSS elevates with the rise in the E-wave and A-wave but the magnitude decreases during the diastasis phase. During the peak E-wave, maximum WSS is found to be 5.7 Pa. Subsequent developments, merging and shifting of the vortices are observed throughout the filling wave. Formations of clockwise vortices are evident during the peak E-wave and at the onset of the A-wave, but counter clockwise vortices are found at the end of the diastasis and at the beginning of the A-wave. Moreover, the maximum magnitude of the structural displacement is seen in the ventricle apex with the value of 3.7E-5 m.
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Affiliation(s)
- Md S Arefin
- Biomechanical and Tissue Engineering Laboratory, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia,
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20
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Fan Z, Sun A, Liu X, Fan Y, Zhao P, Deng X. The accelerated atherogenesis of venous grafts might be attributed to aggravated concentration polarization of low density lipoproteins: a numerical study. J Biomech 2013; 46:2388-93. [PMID: 23972425 DOI: 10.1016/j.jbiomech.2013.07.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/23/2013] [Accepted: 07/23/2013] [Indexed: 11/19/2022]
Abstract
We hypothesize that after implantation the much elevated water filtration rate of venous grafts may cause aggravated concentration polarization of low density lipoproteins (LDLs), in turn lead to the accelerated atherogenesis of the grafts. To verify the hypothesis, we numerically simulated the transport of LDLs in various models of arterial bypasses with different grafts (veins or arteries) and geometrical configurations. The results showed that the venous grafts might endure abnormally high lipid infiltration/accumulation within the vessel wall due to severely elevated luminal surface LDL concentration. When compared to the conventional bypass models, the S-type bypass had the lowest luminal surface LDL concentration along its host artery floor, but the highest degree of risk to develop atherosclerotic lesions in its venous graft. Among the three conventional bypass models, the one with 30° anastomosis had the lowest risk to develop atherosclerosis in the venous graft. In conclusion, when compared with the bypass models with arterial grafts, the venous bypass models had rather high levels of LDL concentration polarization (cw) in the vein grafts, especially at the early stages of implantation. This might result in high infiltration/accumulation of LDLs within the walls of the venous grafts, leading to a fast genesis/development of atherosclerosis there.
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Affiliation(s)
- Zhenmin Fan
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
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Owida AA, Do H, Morsi YS. Numerical analysis of coronary artery bypass grafts: an over view. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2012; 108:689-705. [PMID: 22217920 DOI: 10.1016/j.cmpb.2011.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 09/19/2011] [Accepted: 12/10/2011] [Indexed: 05/31/2023]
Abstract
Arterial bypass grafts tend to fail after some years due to the development of intimal thickening (restenosis). Non-uniform hemodynamics following a bypass operation contributes to restenosis and bypass failure can occur due to the focal development of anastomotic intimal hyperplasia. Additionally, surgical injury aggravated by compliance mismatch between the graft and artery has been suggested as an initiating factor for progress of wall thickening along the suture line Vascular grafts that are small in diameter tend to occlude rapidly. Computational fluid dynamics (CFD) methods have been effectively used to simulate the physical and geometrical parameters characterizing the hemodynamics of various arteries and bypass configurations. The effects of such changes on the pressure and flow characteristics as well as the wall shear stress during a cardiac cycle can be simulated. Recently, utilization of fluid and structure interactions have been used to determine fluid flow parameters and structure forces including stress and strains relationships under steady and transient conditions. In parallel to this, experimental diagnostics techniques such as Laser Doppler Anemometry, Particle Image Velocimetry, Doppler Guide wire and Magnetic Resonance Imaging have been used to provide essential information and to validate the numerical results. Moreover, clinical imaging techniques such as magnetic resonance or computed tomography have assisted considerably in gaining a detailed patient-specific picture of the blood flow and structure dynamics. This paper gives a review of recent numerical investigations of various configurations of coronary artery bypass grafts (CABG). In addition, the paper ends with a summary of the findings and the future directions.
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Affiliation(s)
- Amal Ahmed Owida
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, Australia
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22
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Ene-Iordache B, Cattaneo L, Dubini G, Remuzzi A. Effect of anastomosis angle on the localization of disturbed flow in 'side-to-end' fistulae for haemodialysis access. Nephrol Dial Transplant 2012; 28:997-1005. [PMID: 22785110 DOI: 10.1093/ndt/gfs298] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Early failure of the vascular access for haemodialysis (HD) after the surgical creation of a radial-cephalic arteriovenous fistula (AVF) occurs mainly due to a juxta-anastomotic stenosis. Even if elevated blood flow induces high wall shear stress, we have recently shown that disturbed flow, characterized by low and reciprocating flow, may develop in zones of the AVF where it can provide a good indication of the sites of future stenoses. The present study was aimed at investigating whether the anastomosis angle influences disturbed flow in radial-cephalic 'side-to-end' AVF. METHODS By means of a parametric AVF model we created four equivalent meshes with anastomosis angles of 30°, 45°, 60° and 90°, respectively. We then performed transient, non-Newtonian computational fluid dynamics simulations using, as boundary conditions, previously measured blood volume flow and division ratio in subjects requiring primary access. The relative residence time (RRT), a robust indicator of disturbed flow, was calculated for the overall wall surface and disturbed flow was localized as areas having RRT > 1. Quantitative characterization and statistical tests were employed to assess the difference in RRT medians between the four anastomosis angle cases. RESULTS Disturbed flow was located in all AVF models in the same areas where flow recirculation and stagnation occurred, on the inner wall of the swing segment (SS) and on the arterial wall at the anastomosis floor (AF). A smaller angle AVF had smaller disturbed flow areas with lower RRT peak values, either on the venous or the arterial limb. There were significant differences in the RRT medians on the SS and on the AF between sharper (30° and 45°) and wider (60° or 90°) angles. CONCLUSIONS We have found that in 'side-to-end' radial-cephalic AVFs for HD, the anastomosis angle does impact on the local disturbed flow patterns. Among the four geometries we considered in this study, the smaller angle (30°) would be the preferred choice that minimizes the development of neointima. Clinicians should consider this at the time of AVF creation because the anastomosis angle is in part amenable to surgical manipulation.
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Affiliation(s)
- Bogdan Ene-Iordache
- Clinical Research Center for Rare Diseases Aldo e Cele Daccò, Mario Negri Institute for Pharmacological Research, Ranica, BG, Italy.
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Swillens A, De Witte M, Nordgaard H, Løvstakken L, Van Loo D, Trachet B, Vierendeels J, Segers P. Effect of the degree of LAD stenosis on "competitive flow" and flow field characteristics in LIMA-to-LAD bypass surgery. Med Biol Eng Comput 2012; 50:839-49. [PMID: 22707228 DOI: 10.1007/s11517-012-0927-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 05/28/2012] [Indexed: 11/30/2022]
Abstract
The long-term patency of the left internal mammary artery (LIMA) in left anterior descending (LAD) coronary stenosis bypass surgery is believed to be related to the degree of competitive flow between the LAD and LIMA. To investigate the effect of the LAD stenosis severity on this phenomenon and on haemodynamics in the LIMA and anastomosis region, a numerical LIMA-LAD model was developed based on 3D geometric (obtained from a cast) and hemodynamic data from an experimental pig study. Proximal LAD pressure was used as upstream boundary condition. The model counted 13 outlets (12 septal arteries and the distal LAD) where flow velocities were imposed in systole, while myocardial conductance was imposed in diastole via an implicit scheme. LAD stenoses of 100 (total occlusion), 90, 75 and 0 % area reduction were constructed. Low degree of LAD stenosis was associated with highly competitive flow and low wall shear stress (WSS) in the LIMA, an unfavourable hemodynamic regime which might contribute to WSS-related remodelling of the LIMA and suboptimal long-term LIMA bypass performance.
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OWIDA AMAL, DO HUNG, YANG WILLIAM, MORSI YOSS. PIV MEASUREMENTS AND NUMERICAL VALIDATION OF END-TO-SIDE ANASTOMOSIS. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519410003265] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this article, particle image velocimetry (PIV) technique was used to determine the instantaneous velocity fields inside a model of end-to-side anastomosis under various physiological flow conditions. Using ANSYS software, a three-dimensional (3D) computational model at the peak systolic blood flow was simulated. The numerical and experimental results were presented and discussed in terms of velocity fields at various locations along the graft and the host artery. The numerical results were then compared with the experimental data and a large difference was found, which was attributed to the imperfection of manufacturing the glass model and measurements error associated with PIV. The findings indicated in general that the analysis at peak systole, steady flow could help in providing essential quantitative information of the hemodynamics in anastomotic artery.
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Affiliation(s)
- AMAL OWIDA
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, VIC, Australia
| | - HUNG DO
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, VIC, Australia
| | - WILLIAM YANG
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, VIC, Australia
- Division of Minerals, CSIRO, Melbourne, VIC, Australia
| | - YOS S. MORSI
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, VIC, Australia
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Choi JS, Hong SC, Kwon HM, Suh SH, Lee JS. Influences of Geometric Configurations of Bypass Grafts on Hemodynamics in End-to-Side Anastomosis. THE KOREAN JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY 2012; 44:89-98. [PMID: 22263134 PMCID: PMC3249301 DOI: 10.5090/kjtcs.2011.44.2.89] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 03/17/2011] [Accepted: 03/17/2011] [Indexed: 11/22/2022]
Abstract
Background Although considerable efforts have been made to improve the graft patency in coronary artery bypass surgery, the role of biomechanical factors remains underrecognized. The aim of this study is to investigate the influences of geometric configurations of the bypass graft on hemodynamic characteristics in relation to anastomosis. Materials and Methods The Numerical analysis focuses on understanding the flow patterns for different values of inlet and distal diameters and graft angles. The Blood flow field is treated as a two-dimensional incompressible laminar flow. A finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as a constitutive equation for blood. In an attempt to obtain the optimal aorto-coronary bypass conditions, the blood flow characteristics are analyzed using in vitro models of the end-to-side anastomotic angles of 45°, 60° and 90°. To find the optimal graft configurations, the mass flow rates at the outlets of the four models are compared quantitatively. Results This study finds that Model 3, whose bypass diameter is the same as the inlet diameter of the stenosed coronary artery, delivers the largest amount of blood and the least pressure drop along the arteries. Conclusion Biomechanical factors are speculated to contribute to the graft patency in coronary artery bypass grafting.
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Affiliation(s)
- Jae-Sung Choi
- Deptartment of Thoracic and Cardiovascular Surgery, Seoul National University Boramae Hospital, Korea
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Morsi YS, Owida AA, Do H, Arefin MS, Wang X. Graft-artery junctions: design optimization and CAD development. Methods Mol Biol 2012; 868:269-287. [PMID: 22692616 DOI: 10.1007/978-1-61779-764-4_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Designing and manufacturing of vascular prosthesis for arterial bypass grafts is a very complex problem. The process involves the selection of suitable geometry, materials of appropriate characteristics, and manufacturing technique capable of constructing prosthesis in a cost-effective manner. In this chapter, all engineering aspects related to the design and optimization of an artificial graft are presented and discussed. These aspects include CAD design of the graft, in vitro hemodynamic analysis to ensure good mechanical integrity and functionality, and optimization of the manufacturing techniques. Brief discussion is also given on the endothelization and vascularization of the artificial vessels and the future directions of the development of synthetic vessels for human implementation.
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Affiliation(s)
- Yos S Morsi
- Biomechanics and Tissue Engineering Group, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Melbourne, Australia.
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27
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Maagh P, Wickenbrock I, Prull MW, Schrage MO, Butz T, Trappe HJ, Meissner A. Percutaneous coronary intervention in patients with acute myocardial infarction due to congenital coronary anomalies: technical skills and clinical outcome. ACUTE CARDIAC CARE 2011; 13:148-154. [PMID: 21410310 DOI: 10.3109/17482941.2011.553235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Petra Maagh
- Department of Cardiology and Angiology, Ruhr-University Bochum, Germany.
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Abstract
Computational fluid dynamics (CFD) is a mechanical engineering field for analyzing fluid flow, heat transfer, and associated phenomena, using computer-based simulation. CFD is a widely adopted methodology for solving complex problems in many modern engineering fields. The merit of CFD is developing new and improved devices and system designs, and optimization is conducted on existing equipment through computational simulations, resulting in enhanced efficiency and lower operating costs. However, in the biomedical field, CFD is still emerging. The main reason why CFD in the biomedical field has lagged behind is the tremendous complexity of human body fluid behavior. Recently, CFD biomedical research is more accessible, because high performance hardware and software are easily available with advances in computer science. All CFD processes contain three main components to provide useful information, such as pre-processing, solving mathematical equations, and post-processing. Initial accurate geometric modeling and boundary conditions are essential to achieve adequate results. Medical imaging, such as ultrasound imaging, computed tomography, and magnetic resonance imaging can be used for modeling, and Doppler ultrasound, pressure wire, and non-invasive pressure measurements are used for flow velocity and pressure as a boundary condition. Many simulations and clinical results have been used to study congenital heart disease, heart failure, ventricle function, aortic disease, and carotid and intra-cranial cerebrovascular diseases. With decreasing hardware costs and rapid computing times, researchers and medical scientists may increasingly use this reliable CFD tool to deliver accurate results. A realistic, multidisciplinary approach is essential to accomplish these tasks. Indefinite collaborations between mechanical engineers and clinical and medical scientists are essential. CFD may be an important methodology to understand the pathophysiology of the development and progression of disease and for establishing and creating treatment modalities in the cardiovascular field.
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Affiliation(s)
- Byoung-Kwon Lee
- Division of Cardiology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Zhang T, Taskin ME, Fang HB, Pampori A, Jarvik R, Griffith BP, Wu ZJ. Study of flow-induced hemolysis using novel Couette-type blood-shearing devices. Artif Organs 2011; 35:1180-6. [PMID: 21810113 DOI: 10.1111/j.1525-1594.2011.01243.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To assist the development and application of blood-contacting medical devices, two novel flow-through Couette-type blood-shearing devices have been developed to study the quantitative relationship between blood damage indexes and flow-dependent parameters. One device is an axial flow-through Couette-type device supported by a pair of pin bearings adapted from the adult Jarvik 2000 blood pump. The other is a centrifugal flow-through Couette-type device supported with magnetic bearings adapted from the CentriMag blood pump. In both devices, a rotor spindle was used to replace the original impeller blades so that a small gap was created between the housing and the rotating spindle surface. Computational fluid dynamics simulations have shown that a uniform, high shear stress region can be generated inside the small gap while the shear stresses elsewhere are relatively low. The possibility of secondary blood damage caused by mechanical seals was eliminated due to the use of a magnetic rotor system. Blood flow through the gap was driven by an externally pressurized reservoir. By adjusting the rotational speed and blood flow rate, shear-induced hemolysis was quantified at a matrix of exposure time (0.039 to 1.48 s) and shear stress (50 to 320 Pa). All of the experiments were conducted at room temperature using heparinized ovine blood with a hematocrit value of 30%. The measured hemolysis levels were much lower than those published in the literature, and the overestimation of those earlier studies may be attributable to device-related secondary blood-damaging effects. A new set of coefficients for the power law model was derived from the regression of the experimental data.
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Affiliation(s)
- Tao Zhang
- Artificial Organs Laboratory, Department of Surgery, University of Maryland Baltimore, USA
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John LCH. Biomechanics of coronary artery and bypass graft disease: potential new approaches. Ann Thorac Surg 2009; 87:331-8. [PMID: 19101335 DOI: 10.1016/j.athoracsur.2008.07.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 07/08/2008] [Accepted: 07/09/2008] [Indexed: 12/01/2022]
Abstract
The contribution of biomechanical factors to the incidence and distribution of coronary artery and bypass graft disease is underrecognized. This review examined the literature to determine which factors were relevant and the evidence for their importance. It identified two primary biomechanical factors that predispose to disease: (1) low-wall shear stress and (2) high-wall mechanical stress or strain. A range of secondary biomechanical factors have also been identified and include: vessel geometry; vessel movement; vessel wall characteristics and the presence of reflection waves. Potential surgical approaches for minimizing these effects are discussed.
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Affiliation(s)
- Lindsay C H John
- Department of Cardiothoracic Surgery, Kings College Hospital, London, United Kingdom.
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Kouhi E, Morsi YS, Masood SH. Haemodynamic analysis of coronary artery bypass grafting in a non-linear deformable artery and Newtonian pulsatile blood flow. Proc Inst Mech Eng H 2008; 222:1273-87. [DOI: 10.1243/09544119jeim459] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A three-dimensional (3D) computational model of stenotic coronary artery bypass grafting (CABG) system with fluid—structure interaction (FSI) using realistic physiological conditions is introduced. Unsteady pulsatile blood flow is applied to the wall of non-linear deformable arteries over the systolic period. In the analysis, the arbitrarily Lagrangian—Eulerian (ALE) formulation is used to couple the fluid region and solid domain. The method couples the equations of the deformation of the artery wall and applies them as the fluid domain boundary condition. The flow distribution and haemodynamic forces are presented in terms of velocity profiles and temporal and spatial wall shear stresses (WSSs) at the distal area. Rapid changes in the flow fields are observed in the early stages of the cardiac cycle, which alters the location of the recirculation zone from the toe to the host bed and then to the heel. The migration of the recirculation zone, considering the effect of deformability of the artery wall, indicates the same trend as the rigid wall model according to the location of low and high WSSs. However, the WSSs in the critical areas such as toe, heel, and suture lines are found to have dramatic drops in magnitudes in comparison with those of the rigid wall model. This could initiate the promotion of intimal hyperplasia (IH) and may cause an early graft failure in CABG.
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Affiliation(s)
- E Kouhi
- Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Y S Morsi
- Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - S H Masood
- Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, Victoria, Australia
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Araki M, Miyamoto M. Acute myocardial infarction of the right coronary artery originating from the distal left circumflex artery. Circ J 2008; 72:2092-5. [PMID: 18854618 DOI: 10.1253/circj.cj-07-0747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A case of acute myocardial infarction (AMI) of the distal left circumflex, near the origin of an aberrant right coronary artery is presented. Coronary stenting was successfully performed. According to several reports, this anomaly is a common site for coronary atherosclerosis, but this is the first report of AMI.
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Affiliation(s)
- Masaru Araki
- Department of Internal Medicine, Moji Rosai Hospital, Kitakyushu, Japan.
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Frauenfelder T, Boutsianis E, Schertler T, Husmann L, Leschka S, Poulikakos D, Marincek B, Alkadhi H. Flow and wall shear stress in end-to-side and side-to-side anastomosis of venous coronary artery bypass grafts. Biomed Eng Online 2007; 6:35. [PMID: 17897460 PMCID: PMC2089073 DOI: 10.1186/1475-925x-6-35] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Accepted: 09/26/2007] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Coronary artery bypass graft (CABG) surgery represents the standard treatment of advanced coronary artery disease. Two major types of anastomosis exist to connect the graft to the coronary artery, i.e., by using an end-to-side or a side-to-side anastomosis. There is still controversy because of the differences in the patency rates of the two types of anastomosis. The purpose of this paper is to non-invasively quantify hemodynamic parameters, such as mass flow and wall shear stress (WSS), in end-to-side and side-to-side anastomoses of patients with CABG using computational fluid dynamics (CFD). METHODS One patient with saphenous CABG and end-to-side anastomosis and one patient with saphenous CABG and side-to-side anastomosis underwent 16-detector row computed tomography (CT). Geometric models of coronary arteries and bypasses were reconstructed for CFD analysis. Blood flow was considered pulsatile, laminar, incompressible and Newtonian. Peri-anastomotic mass flow and WSS were quantified and flow patterns visualized. RESULTS CFD analysis based on in-vivo CT coronary angiography data was feasible in both patients. For both types of CABG, flow patterns were characterized by a retrograde flow into the native coronary artery. WSS variations were found in both anastomoses types, with highest WSS values at the heel and lowest WSS values at the floor of the end-to-side anastomosis. In contrast, the highest WSS values of the side-to-side anastomosis configuration were found in stenotic vessel segments and not in the close vicinity of the anastomosis. Flow stagnation zones were found in end-to-side but not in side-to-side anastomosis, the latter also demonstrating a smoother stream division throughout the cardiac cycle. CONCLUSION CFD analysis of venous CABG based on in-vivo CT datasets in patients was feasible producing qualitative and quantitative information on mass flow and WSS. Differences were found between the two types of anastomosis warranting further systematic application of the presented methodology on multiple patient datasets.
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Affiliation(s)
- Thomas Frauenfelder
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Evangelos Boutsianis
- Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, Zurich, Switzerland
| | - Thomas Schertler
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Lars Husmann
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Sebastian Leschka
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, Zurich, Switzerland
| | - Borut Marincek
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Hatem Alkadhi
- Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
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