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Xiao Z, Postma RJ, van Zonneveld AJ, van den Berg BM, Sol WM, White NA, van de Stadt HJ, Mirza A, Wen J, Bijkerk R, Rotmans JI. A bypass flow model to study endothelial cell mechanotransduction across diverse flow environments. Mater Today Bio 2024; 27:101121. [PMID: 38988818 PMCID: PMC11234155 DOI: 10.1016/j.mtbio.2024.101121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/07/2024] [Accepted: 06/08/2024] [Indexed: 07/12/2024] Open
Abstract
Disturbed flow is one of the pathological initiators of endothelial dysfunction in intimal hyperplasia (IH) which is commonly seen in vascular bypass grafts, and arteriovenous fistulas. Various in vitro disease models have been designed to simulate the hemodynamic conditions found in the vasculature. Nonetheless, prior investigations have encountered challenges in establishing a robust disturbed flow model, primarily attributed to the complex bifurcated geometries and distinctive flow dynamics. In the present study, we aim to address this gap by introducing an in vitro bypass flow model capable of inducing disturbed flow and other hemodynamics patterns through a pulsatile flow in the same model. To assess the model's validity, we employed computational fluid dynamics (CFD) to simulate hemodynamics and compared the morphology and functions of human umbilical venous endothelial cells (HUVECs) under disturbed flow conditions to those in physiological flow or stagnant conditions. CFD analysis revealed the generation of disturbed flow within the model, pinpointing the specific location in the channel where the effects of disturbed flow were observed. High-content screening, a single-cell morphological profile assessment, demonstrated that HUVECs in the disturbed flow area exhibited random orientation, and morphological features were significantly distinct compared to cells in the physiological flow or stagnant condition after a two days of flow exposure. Furthermore, HUVECs exposed to disturbed flow underwent extensive remodeling of the adherens junctions and expressed higher levels of endothelial cell activation markers compared to other hemodynamic conditions. In conclusion, our in vitro bypass flow model provides a robust platform for investigating the associations between disturbed flow pattern and vascular diseases.
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Affiliation(s)
- Zhuotao Xiao
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China
| | - Rudmer J. Postma
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Anton Jan van Zonneveld
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Bernard M. van den Berg
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Wendy M.P.J. Sol
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Nicholas A. White
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
- Department of BioMechanical Engineering, Delft University of Technology, Delft, 2628, CN, Netherlands
| | - Huybert J.F. van de Stadt
- Department of Medical Technology, Design & Prototyping, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Asad Mirza
- Department of Biomedical Engineering, Florida International University, Miami, FL, 33199, United States
| | - Jun Wen
- Department of Computer Science and Technology, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Roel Bijkerk
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
| | - Joris I. Rotmans
- Department of Internal Medicine (Nephrology) and the Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, Leiden, 2333, ZA, Netherlands
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Rassoli A, Changizi S, Behrouz Jazi A, Ghorbani P. Comparison of the mechanical properties of bypass grafts: Experimental assays. Vascular 2024:17085381241264309. [PMID: 39027964 DOI: 10.1177/17085381241264309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
OBJECTIVE One prevalent therapeutic strategy for addressing atherosclerosis is using an alternative blood supply route to the heart, referred to as bypass surgery. In these surgeries, the saphenous vein, radial artery, and internal mammary artery are commonly used to create this bypass route. Unfortunately, due to negligence regarding the compatibility of the graft with the host tissue, reoperation is often required after several years. One method that can aid in selecting a suitable vein for bypass is simulating the solid-fluid interaction, and performing such simulations requires knowledge of the mechanical properties of bypass grafts. Therefore, extracting the mechanical properties of bypass grafts is essential. METHODS In this study, human bypass grafts were subjected to uniaxial tensile testing, and their elastic modulus was extracted and compared. Additionally, the hyperelastic properties of these grafts were extracted using the Mooney-Rivlin model for use in numerical software. RESULTS The average elastic modulus in the circumferential direction for radial artery, mammary artery, and saphenous vein samples were determined to be 1.384 ± 0.268 MPa, 3.108 ± 1.652 MPa, and 7.912 ± 2.509 MPa, respectively. Based on the results of uniaxial tests, the saphenous vein exhibited the highest stiffness among the three vascular tissues. CONCLUSION The mechanical characterization results of the bypass vessels can be applied to the clinical studies of heart diseases. They may help develop an appropriate treatment approach.
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Affiliation(s)
- Aisa Rassoli
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
| | - Shirin Changizi
- Department of Biomedical Engineering and science, Florida Institute of Technology, Melbourne, FL, USA
| | - Alireza Behrouz Jazi
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
| | - Paniz Ghorbani
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
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Wei Z, Ma X, Li J, Yang J, Wei H, Yu Y, Gu C, Huang X. Distal end side-to-side anastomosis of sequential coronary bypass for size mismatched saphenous vein grafts and coronary arteries. Perfusion 2023; 38:1250-1259. [PMID: 35608439 DOI: 10.1177/02676591221100738] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION The distal end anastomosis is critical to the entire sequential grafts in coronary artery bypass grafting (CABG), but caliber mismatch diminishes the quality of the anastomosis. We aimed to introduce a modified distal end side-to-side (deSTS) anastomosis to handle the size mismatch and compared with classic distal end end-to-side (deETS) anastomosis. METHODS From January 2014 to December 2018, 185 patients who underwent off-pump CABG with size mismatched sequential vein grafts (≥3.5 mm) and target coronaries (1.0-1.5 mm) at the distal end anastomoses were included. We retrospectively reviewed the data of the patients, perioperative and follow-up outcomes were analyzed. RESULTS The deSTS group (n = 67) showed higher anastomotic flow (19.8 ± 8.0 vs 14.9±6.8 mL/min; p < 0.001) and lower pulsatility index (2.7 ± 0.8 vs 3.2 ± 1.0; p = 0.001) than the deETS group (n = 118). Higher incidence of in-hospital myocardial infarction (MI) was found in the deETS group but without significant difference (9.0% vs. 15.3%; p = 0.220). Kaplan-Meier analysis illustrated a relatively lower MI and major adverse cardiovascular and cerebrovascular events (MACCE) incidence in the deSTS group, and the deSTS group was associated with a reduction in long-term death, MI and MACCE in the adjusted Cox regression model. In addition, relatively higher graft patency was found in the deSTS group. CONCLUSIONS The deSTS anastomosis showed superiority in solving size mismatch in sequential CABG, including better intraoperative flow dynamics, ideal long-term graft patency and reduced the incidence of perioperative and follow-up adverse events especially in MI.
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Affiliation(s)
- Ziheng Wei
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Xuqing Ma
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Jingxing Li
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Junfeng Yang
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Hua Wei
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Yang Yu
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Chengxiong Gu
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
| | - Xinsheng Huang
- Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Capital Medical University and National Clinical Research Center for Cardiovascular Diseases, Beijing, China
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Pan C, Xu J, Gao Q, Li W, Sun T, Lu J, Shi Q, Han Y, Gao G, Li J. Sequentially suspended 3D bioprinting of multiple-layered vascular models with tunable geometries for in vitromodeling of arterial disorders initiation. Biofabrication 2023; 15:045017. [PMID: 37579751 DOI: 10.1088/1758-5090/aceffa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/14/2023] [Indexed: 08/16/2023]
Abstract
As the main precursor of arterial disorders, endothelial dysfunction preferentially occurs in regions of arteries prone to generating turbulent flow, particularly in branched regions of vasculatures. Although various diseased models have been engineered to investigate arterial pathology, producing a multiple-layered vascular model with branched geometries that can recapitulate the critical physiological environments of human arteries, such as intercellular communications and local turbulent flows, remains challenging. This study develops a sequentially suspended three-dimensional bioprinting (SSB) strategy and a visible-light-curable decellularized extracellular matrix bioink (abbreviated as 'VCD bioink') to construct a biomimetic human arterial model with tunable geometries. The engineered multiple-layered arterial models with compartmentalized vascular cells can exhibit physiological functionality and pathological performance under defined physiological flows specified by computational fluid dynamics simulation. Using different configurations of the vascular models, we investigated the independent and synergetic effects of cellular crosstalk and abnormal hemodynamics on the initiation of endothelial dysfunction, a hallmark event of arterial disorder. The results suggest that the arterial model constructed using the SSB strategy and VCD bioinks has promise in establishing diagnostic/analytic platforms for understanding the pathophysiology of human arterial disorders and relevant abnormalities, such as atherosclerosis, aneurysms, and ischemic diseases.
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Affiliation(s)
- Chen Pan
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jingwen Xu
- School of Biomedical Sciences and Engineering, South China University of Technology, Guangzhou International Campus, Guangzhou 511442, People's Republic of China
- National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou 510006, People's Republic of China
| | - Qiqi Gao
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Wei Li
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Tao Sun
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
- Key Laboratory of Biomimetic Robots and Systems (Beijing Institute of Technology), Ministry of Education, Beijing 100081, People's Republic of China
| | - Jiping Lu
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Qing Shi
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
- Key Laboratory of Biomimetic Robots and Systems (Beijing Institute of Technology), Ministry of Education, Beijing 100081, People's Republic of China
| | - Yafeng Han
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Ge Gao
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jinhua Li
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China
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Yao Y, Pohan G, Cutiongco MFA, Jeong Y, Kunihiro J, Zaw AM, David D, Shangguan H, Yu ACH, Yim EKF. In vivo evaluation of compliance mismatch on intimal hyperplasia formation in small diameter vascular grafts. Biomater Sci 2023; 11:3297-3307. [PMID: 36943136 PMCID: PMC10160004 DOI: 10.1039/d3bm00167a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Small diameter synthetic vascular grafts have high failure rate due to the thrombosis and intimal hyperplasia formation. Compliance mismatch between the synthetic graft and native artery has been speculated to be one of the main causes of intimal hyperplasia. However, changing the compliance of synthetic materials without altering material chemistry remains a challenge. Here, we used poly(vinyl alcohol) (PVA) hydrogel as a graft material due to its biocompatibility and tunable mechanical properties to investigate the role of graft compliance in the development of intimal hyperplasia and in vivo patency. Two groups of PVA small diameter grafts with low compliance and high compliance were fabricated by dip casting method and implanted in a rabbit carotid artery end-to-side anastomosis model for 4 weeks. We demonstrated that the grafts with compliance that more closely matched with rabbit carotid artery had lower anastomotic intimal hyperplasia formation and higher graft patency compared to low compliance grafts. Overall, this study suggested that reducing the compliance mismatch between the native artery and vascular grafts is beneficial for reducing intimal hyperplasia formation.
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Affiliation(s)
- Yuan Yao
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Grace Pohan
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Marie F A Cutiongco
- Mechanobiology Institute, National University of Singapore, 9 Engineering Drive 1, Singapore 117575
- Division of Cell Matrix Biology and Regenerative Medicine, The University of Manchester, Oxford Road, Manchester, UK M13 9PL
| | - YeJin Jeong
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Joshua Kunihiro
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Aung Moe Zaw
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Dency David
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
| | - Hanyue Shangguan
- Schlegel Research Institute for Aging, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
- Center for Biotechnology and Bioengineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
| | - Alfred C H Yu
- Schlegel Research Institute for Aging, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
- Center for Biotechnology and Bioengineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
| | - Evelyn K F Yim
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1.
- Mechanobiology Institute, National University of Singapore, 9 Engineering Drive 1, Singapore 117575
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
- Center for Biotechnology and Bioengineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L 3G1
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Tran-Nguyen N, Condemi F, Yan A, Fremes S, Triverio P, Jimenez-Juan L. Wall Shear Stress Differences Between Arterial and Venous Coronary Artery Bypass Grafts One Month After Surgery. Ann Biomed Eng 2022; 50:1882-1894. [PMID: 35881267 DOI: 10.1007/s10439-022-03007-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 07/02/2022] [Indexed: 12/30/2022]
Abstract
Although coronary artery bypass graft (CABG) surgery is a well-established intervention, graft failure can occur, and the underlying mechanisms remain incompletely understood. The purpose of this prospective study is to utilize computational fluid dynamics (CFD) to investigate how graft hemodynamics one month post surgery may vary among graft types, which have different long-term patency rates. Twenty-four grafts from 10 participants (64.6 ± 8.5 years, 9 men) were scanned with coronary CT angiography and 4D flow MRI one month after CABG surgery. Grafts included 10 left internal mammary arteries (LIMA), 3 radial arteries (RA), and 11 saphenous vein grafts (SVG). Image-guided CFD was used to quantify blood flow rate and wall area exposed to abnormal wall shear stress (WSS). Arterial grafts had a lower abnormal WSS area than venous grafts (17.9% vs. 70.1%; p = 0.001), and a similar trend was observed for LIMA vs. SVG (13.8% vs. 70.1%; p = 0.001). Abnormal WSS area correlated positively to lumen diameter (p < 0.001) and negatively to flow rate (p = 0.001). This CFD study is the first of its kind to prospectively reveal differences in abnormal WSS area 1 month post surgery among CABG types, suggesting that WSS may influence the differential long-term graft failure rates observed among these groups.
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Affiliation(s)
- Nhien Tran-Nguyen
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
| | | | - Andrew Yan
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
- St. Michael's Hospital, Toronto, ON, Canada
| | - Stephen Fremes
- Department of Surgery, University of Toronto, Toronto, ON, Canada
- Sunnybrook Health Sciences Centre, Toronto, ON, Canada
- Sunnybrook Research Institute, Toronto, ON, Canada
| | - Piero Triverio
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Laura Jimenez-Juan
- Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
- St. Michael's Hospital, Toronto, ON, Canada
- Sunnybrook Research Institute, Toronto, ON, Canada
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7
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Zainib Z, Ballarin F, Fremes S, Triverio P, Jiménez-Juan L, Rozza G. Reduced order methods for parametric optimal flow control in coronary bypass grafts, toward patient-specific data assimilation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3367. [PMID: 32458572 DOI: 10.1002/cnm.3367] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
Coronary artery bypass grafts (CABG) surgery is an invasive procedure performed to circumvent partial or complete blood flow blockage in coronary artery disease. In this work, we apply a numerical optimal flow control model to patient-specific geometries of CABG, reconstructed from clinical images of real-life surgical cases, in parameterized settings. The aim of these applications is to match known physiological data with numerical hemodynamics corresponding to different scenarios, arisen by tuning some parameters. Such applications are an initial step toward matching patient-specific physiological data in patient-specific vascular geometries as best as possible. Two critical challenges that reportedly arise in such problems are: (a) lack of robust quantification of meaningful boundary conditions required to match known data as best as possible and (b) high computational cost. In this work, we utilize unknown control variables in the optimal flow control problems to take care of the first challenge. Moreover, to address the second challenge, we propose a time-efficient and reliable computational environment for such parameterized problems by projecting them onto a low-dimensional solution manifold through proper orthogonal decomposition-Galerkin.
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Affiliation(s)
- Zakia Zainib
- mathLab, Mathematics Area, SISSA-International School for Advance Studies, Trieste, Italy
| | - Francesco Ballarin
- mathLab, Mathematics Area, SISSA-International School for Advance Studies, Trieste, Italy
| | - Stephen Fremes
- Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Piero Triverio
- Department of Electrical and Computer Engineering, Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | | | - Gianluigi Rozza
- mathLab, Mathematics Area, SISSA-International School for Advance Studies, Trieste, Italy
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Du J, Shi J, Liu J, Deng C, Shen J, Wang Q. Hemodynamic analysis of hepatic arteries for the early evaluation of hepatic fibrosis in biliary atresia. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 211:106400. [PMID: 34551379 DOI: 10.1016/j.cmpb.2021.106400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Hepatic fibrosis is the prominent characteristic of biliary atresia (BA), may even progress continually after Kasai procedure (KP). BA, as a devastating pediatric hepatic disease, mainly leads to newborn cholestasis, even liver cirrhosis, eventually hepatic failure. Earlier diagnosis of hepatic fibrosis, which used to be detected by liver biopsy commonly, is consistent with better outcomes of KP. Due to potential risks and uncertainty of liver biopsy, it is an urge to seek a safer and more precise evaluation method as alternative. The purpose of this study is to investigate the hemodynamics of hepatic artery (HA) in hepatic fibrosis of early BA based on computational fluid dynamics (CFD) for evaluating the value of CFD for hepatic fibrosis diagnosis. METHODS 40 patients were divided into three groups, including the control group, the abnormal liver function group and the mild to moderate hepatic fibrosis group. CFD was applied to quantify primary hemodynamic parameters of HA and related arteries, including blood flow distribution ratio (FDR), pressure, wall shear stress (WSS) and energy loss (EL). Statistical analyses were also performed to compare the differences amongst these above groups. RESULTS With the progression of hepatic fibrosis, the increasing tendency of hemodynamic parameters values of HA and related arteries were observed. Values of FDR, pressure, WSS and EL of the mild to moderate group was higher than those of the control group and the abnormal liver function group. There were significant differences on FDRAA, FDRHA and EL between the control group and the mild to moderate hepatic fibrosis group (t = 0.037, 0.030 and <0.001, P < 0.05). CONCLUSION Significant variations of HA hemodynamics acquired by CFD between the control group and the mild to moderate hepatic fibrosis group demonstrated the relationship between the progression of hepatic fibrosis and the hemodynamic disorder, and suggested that CFD had the potential to assist the diagnosis of hepatic fibrosis in early BA.
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Affiliation(s)
- Jun Du
- Department of Medical Imaging, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Shanghai 200127, China
| | - Jing Shi
- Department of Medical Imaging, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Shanghai 200127, China
| | - Jinlong Liu
- Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chaohui Deng
- Department of Gastroenterology, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Juanya Shen
- Department of Cardiothoracic Surgery, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Engineering Research Center of Virtual Reality of Structural Heart Disease, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qian Wang
- Department of Medical Imaging, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 1678 Dongfang Road, Shanghai 200127, China.
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Nikolić A, Topalović M, Simić V, Filipović N. Turbulent finite element model applied for blood flow calculation in arterial bifurcation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 209:106328. [PMID: 34407452 DOI: 10.1016/j.cmpb.2021.106328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Due to the relatively low fluid velocities in major arteries and veins, blood flow is by default laminar, however, turbulence can occur as a result of stenosis or other obstacles. Hemodynamic parameters like Wall Shear Stress or Oscillatory Shear Index can be used for plaque formation prediction, and these parameters are depended on the nature of the flow. Implementation of the k-ω turbulent flow in the Finite Element solver aims to improve numerical analysis of cardio-vascular condition development and progression. Calculation of turbulent fluid flow in this paper is performed using a two-equation turbulent finite element model that can calculate values in the viscous sublayer. METHODS Implicit integration of the equations is used for determining the fluid velocity, turbulent kinetic energy and dissipation of turbulent kinetic energy. These values are calculated in the finite element nodes for each step of the incremental-iterative procedure. Developed turbulent finite element model with the customized generation of finite element meshes is used for calculating complex blood flow problems. RESULTS Turbulent model is verified on an example of fluid flow in the backward-facing step channel and analysis results correspond well with the experimental ones from the literature. Further, a turbulent model is applied for the simulation of blood flow through artery bifurcation. Verification of numerical examples obtained using different commercial software packages (Ansys, COMSOL Multiphysics) ensuring usage and accuracy of PAK in-house solver. CONCLUSIONS Analysis results show that turbulence cannot be neglected in the modelling of cardio-vascular conditions and that cardiologists can use the proposed tools and methods for investigating the hemodynamic conditions inside the bifurcation of arteries. Appropriate agreement between experimental results, and results obtained using commercial solutions and the k-ω turbulent flow in the Finite Element solver PAK, validate methodology presented in this paper. However, small deviations between the results underline the importance of the proper boundary condition prescription and mesh size and node distribution, which is also discussed in this paper. Due to the implicit integration implemented in PAK solver, time step size has an insignificant influence on the analysis results, assuming the initial time increments are sufficiently small to ensure proper discretization of velocity and pressure pulsatile functions.
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Affiliation(s)
- Aleksandar Nikolić
- Institute of Information Technologies, University of Kragujevac, Department of Technical- Technological Sciences, Jovana Cvijića bb, 34000 Kragujevac, Serbia.
| | - Marko Topalović
- Institute of Information Technologies, University of Kragujevac, Department of Technical- Technological Sciences, Jovana Cvijića bb, 34000 Kragujevac, Serbia
| | - Vladimir Simić
- Institute of Information Technologies, University of Kragujevac, Department of Technical- Technological Sciences, Jovana Cvijića bb, 34000 Kragujevac, Serbia
| | - Nenad Filipović
- Faculty of Engineering, University of Kragujevac, Sestre Janjic 6, 34000 Kragujevac, Serbia
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Chen Y, Yang Y, Tan W, Fu L, Deng X, Xing Y. Hemodynamic effects of the human aorta arch with different inflow rate waveforms from the ascending aorta inlet: A numerical study. Biorheology 2021; 58:27-38. [PMID: 33682689 DOI: 10.3233/bir-201009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Heart failure (HF) is a common disease globally. Ventricular assist devices (VADs) are widely used to treat HF. In contrast to the natural heart, different VADs generate different blood flow waves in the aorta. OBJECTIVE To explore whether the different inflow rate waveforms from the ascending aorta generate far-reaching hemodynamic influences on the human aortic arch. METHODS An aortic geometric model was reconstructed based on computed tomography data of a patient with HF. A total of five numerical simulations were conducted, including a case with the inflow rate waveforms from the ascending aorta with normal physiological conditions, two HF, and two with typical VAD support. The hemodynamic parameters, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and the strength of the helical flow, were calculated. RESULTS In contrast to the natural heart, numerical simulations showed that HF decreased WSS and induced higher OSI and RRT. Moreover, HF weakened helical flow strength. Pulsatile flow VADs that elevated the WSS, induced some helical flow, while continuous flow VADs could not. CONCLUSIONS HF leads to an adverse hemodynamic environment by decreasing WSS and reducing the helical flow strength. Based upon hemodynamic effects, pulsatile flow VADs may be more advantageous than continuous flow VADs. Thus, pulsatile flow VADs may be a better option for patients with HF.
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Affiliation(s)
- Ying Chen
- College of Engineering and Technology, Beijing Institute of Economics and Management, Beijing, China.,College of Engineering, Peking University, Beijing, China.,Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Yunmei Yang
- Yanshan County People's Hospital of Hebei, Yanshan, Hebei, China
| | - Wenchang Tan
- College of Engineering, Peking University, Beijing, China.,Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Liqin Fu
- College of Engineering and Technology, Beijing Institute of Economics and Management, Beijing, China
| | - Xiaoyan Deng
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China.,School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong, Sichuan, China
| | - Yubin Xing
- Department of Infection Management and Disease Control, The General Hospital of People's Liberation Army, Beijing, China
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11
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Jonášová A, Vimmr J. On the relevance of boundary conditions and viscosity models in blood flow simulations in patient-specific aorto-coronary bypass models. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3439. [PMID: 33464717 DOI: 10.1002/cnm.3439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/11/2021] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
Physiologically realistic results are the aim of every blood flow simulation. This is not different in aorto-coronary bypasses where the properties of the coronary circulation may significantly affect the relevance of the performed simulations. By considering three patient-specific bypass geometries, the present article focuses on two aspects of the coronary blood flow - its phasic flow pattern and its behaviour affected by blood rheology. For the phasic flow property, a multiscale modelling approach is chosen as a means to assess the ability of five different types of coronary boundary conditions (mean arterial pressure, Windkessel model and three lumped parameter models) to attain realistic coronary haemodynamics. From the analysed variants of boundary conditions, the best option in terms of physiological characteristics and its potential for use in patient-based simulations, is utilised to account for the effect of shear-dependent viscosity on the resulting haemodynamics and wall shear stress stimulation. Aside from the Newtonian model, the blood rheology is approximated by two non-Newtonian models in order to determine whether the choice of a viscosity model is important in simulations involving coronary circulation. A comprehensive analysis of obtained results demonstrated notable superiority of all lumped parameter models, especially in comparison to the constant outlet pressure, which regardless of bypass type gave overestimated and physiologically misleading results. In terms of rheology, it was noted that blood in undamaged coronary arteries behaves as a Newtonian fluid, whereas in vessels with atypical lumen geometry, such as that of anastomosis or stenosis, its shear-thinning behaviour should not be ignored.
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Affiliation(s)
- Alena Jonášová
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic
- Department of Mechanics, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic
| | - Jan Vimmr
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic
- Department of Mechanics, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic
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12
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Chen Y, Xu Z, Deng X, Yang S, Tan W, Fan Y, Han Y, Xing Y. Effects of reverse deployment of cone-shaped vena cava filter on improvements in hemodynamic performance in vena cava. Biomed Eng Online 2021; 20:19. [PMID: 33563284 PMCID: PMC7874631 DOI: 10.1186/s12938-021-00855-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 01/27/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Cone-shaped vena cava filters (VCFs) are widely used to treat venous thromboembolism. However, in the long term, the problem of occlusion persists even after the filter is deployed. A previous study hypothesized that the reverse deployment of a cone-shaped VCFs may prevent filter blockage. METHODS To explore this hypothesis, a comparative study of the traditional and reverse deployments of VCFs was conducted using a computational fluid dynamics approach. The distribution of wall shear stress (WSS) and shear stress-related parameters were calculated to evaluate the differences in hemodynamic effects between both conditions. In the animal experiment, we reversely deployed a filter in the vena cava of a goat and analyzed the blood clot distribution in the filter. RESULTS The numerical simulation showed that the reverse deployment of a VCF resulted in a slightly higher shear rate on the thrombus, and no reductions in the oscillating shear index (OSI) and relative residence time (RRT) on the vessel wall. Comparing the traditional method with the reversely deployed cases, the shear rate values is 16.49 and 16.48 1/s, respectively; the minimal OSI values are 0.01 and 0.04, respectively; in the vicinity of the VCF, the RRT values are both approximately 5 1/Pa; and the WSS is approximately 0.3 Pa for both cases. Therefore, the reverse deployment of cone-shaped filters is not advantageous when compared with the traditional method in terms of local hemodynamics. However, it is effective in capturing thrombi in the short term, as demonstrated via animal experiments. The reversely deployed cone-shaped filter captured the thrombi at its center in the experiments. CONCLUSIONS Thus, the reverse deployment of cone-shaped filters is not advantageous when compared with the traditional method in terms of local hemodynamics. Therefore, we would not suggest the reverse deployment of the cone-shaped filter in the vena cava to prevent a potentially fatal pulmonary embolism.
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Affiliation(s)
- Ying Chen
- College of Engineering and Technology, Beijing Institute of Economics and Management, Beijing, 100102, China.
- College of Engineering, Peking University, Beijing, 100871, China.
- Shenzhen Graduate School, Peking University, Shenzhen, 518055, China.
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China.
| | - Zaipin Xu
- Department of Veterinary Medicine, College of Animal Science, Guizhou University, Guiyang, 550025, Guizhou, China.
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China.
- School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong, 643002, Sichuan, China.
| | - Shibo Yang
- Department of Veterinary Medicine, College of Animal Science, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Wenchang Tan
- College of Engineering, Peking University, Beijing, 100871, China
- Shenzhen Graduate School, Peking University, Shenzhen, 518055, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China
| | - Yong Han
- Guizhou Institute of Animal Husbandry and Veterinary Science, Guiyang, 550025, Guizhou, China
| | - Yubin Xing
- Department of Infection Management and Disease Control, The General Hospital of People's Liberation Army, Beijing, 100853, China
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13
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Alizadehghobadi S, Biglari H, Niroomand-Oscuii H, Matin MH. Numerical study of hemodynamics in a complete coronary bypass with venous and arterial grafts and different degrees of stenosis. Comput Methods Biomech Biomed Engin 2020; 24:883-896. [PMID: 33307817 DOI: 10.1080/10255842.2020.1857744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Cardiovascular diseases are among the leading causes of death in the world. The coronary blockage is one of most common types of these diseases that in the majority of cases has been treated by bypass surgery. In the bypass surgery, a graft is implemented to alter the blocked coronary and allow the blood supply process. The hemodynamic characteristics of the bypass strongly depend on the geometry and mechanical properties of the graft. In the present study, the fluid-structure interaction (FSI) analysis is conducted to investigate the bypass performance for a thoracic artery as well as a saphenous vein graft. Blood flow introduces a pressure on the walls of the graft which behaves as a hyperelastic material. A complete coronary bypass with stenosis degrees of 70% and 100% is modeled. To consider the nonlinear stress-strain behavior of the grafts, a five parameter Mooney-Rivlin hyperplastic model is implemented for the structural analysis and blood is assumed to behave as a Newtonian fluid. The simulations are performed for a structured grid to solve the governing equations using finite element method (FEM). The results show that wall shear stress (WSS) for saphenous vein is larger than that of thoracic artery while the total deformation of the thoracic artery is larger compared to the saphenous vein. Also, for the venous grafts or lower stenosis degree, the oscillatory shear index (OSI) is higher at both left and right anastomoses meaning that venous grafts as well as lower degree of stenosis are more critical in terms of restenosis.
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Affiliation(s)
| | - Hasan Biglari
- Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran
| | | | - Meisam H Matin
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
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14
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Kanzaki T, Numata S, Yamazaki S, Ikemoto K, Hohri Y, Yaku H, Itatani K, Nakajma S, Takahashi A. Computational fluid dynamics of internal mammary artery-left anterior descending artery anastomoses. Interact Cardiovasc Thorac Surg 2020; 31:611-617. [PMID: 33137825 DOI: 10.1093/icvts/ivaa183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/01/2020] [Accepted: 07/20/2020] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The aim of this study was to elucidate the remodelling of the internal mammary artery (IMA)-left anterior descending artery anastomosis and compare 2 different anastomosis techniques (end-to-side versus side-to-side) using computational fluid dynamics. METHODS This study included 9 patients. Computed tomography (CT) angiography was performed immediately after coronary artery bypass grafting (CABG) and at 3-6 months later. The computational fluid dynamics models were made using the CT data. The pulsatile 3-dimensional blood flow was achieved with the finite volume method to evaluate the postoperative morphological and haemodynamic changes at the anastomosis in each patient. Flow velocity distribution, wall shear stress (WSS) and its fluctuation oscillatory shear index were measured. RESULTS No early or mid-term graft occlusion was observed in the study series. In the side-to-side anastomosis, pouch formation at the distal end of IMA caused a vortex flow with low WSS immediately after CABG. However, at 3-6 months after surgery, this pouch disappeared. As a result, the laminar straight flow with uniform WSS distribution was achieved inside the anastomosis. In the end-to-side anastomosis, the anastomosis shape was remodelled, resulting in a laminar flow pattern with uniform WSS distribution. A patchy high oscillatory shear index was detected at the IMA wall on the top of anastomosis in either anastomosis techniques immediately after the surgery, but it disappeared at 3-6 months after surgery. CONCLUSIONS Regardless of the anastomosis technique used, a successful remodelling of the IMA-left anterior descending artery anastomosis shape was achieved a few months after surgery, resulting in a straightforward flow streamline, with uniform WSS distribution and minimal oscillatory shear index.
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Affiliation(s)
- Tomohito Kanzaki
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Satoshi Numata
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Sachiko Yamazaki
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Koki Ikemoto
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yu Hohri
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hitoshi Yaku
- Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Keiichi Itatani
- Department of Cardiovascular Surgery, Cardiovascular Imaging Research Laboratory, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Shunsuke Nakajma
- Department of Cardiology, Sakurakai Takahashi Hospital, Hyogo, Japan
| | - Akihiko Takahashi
- Department of Cardiology, Sakurakai Takahashi Hospital, Hyogo, Japan
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15
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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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16
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Computational fluid dynamic study of multiple sequential coronary artery bypass anastomoses in a native coronary stenosis model. Coron Artery Dis 2020; 31:458-463. [PMID: 32271246 DOI: 10.1097/mca.0000000000000864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The objective of this study was to evaluate the hemodynamic characteristics of multiple sequential coronary artery bypass grafting using a computational fluid dynamics study. METHODS First anastomosis was configured into parallel and diamond anastomoses, and the second anastomosis was set as end-side anastomosis. The anastomosis incision lengths were fixed at 2 mm. Various combinations of the degree of first and second stenoses were studied. The diameter of both the native and graft vessels was set at 2 mm. The inlet boundary condition was set by a sample of the transient time flow measurement, which was measured intraoperatively. RESULTS Both swirl and stagnation were observed at the outlets of the stenosis and the anastomosis sites. When the severity of the second stenosis was larger than that of the first, the flow at the outlet of the second stenosis was more unstable. Higher wall shear stress and larger oscillatory shear index regions were observed when the severe stenosis was bypassed by the first anastomosis, especially with diamond anastomoses. Less energy loss and higher energy efficiency were present when the vessel with more severe stenosis was bypassed as the second anastomosis. Energy loss was lower and energy efficiency was higher with parallel anastomosis than diamond anastomosis when the severity of the two stenoses was the same. CONCLUSIONS It is ideal to bypass the less severe stenosis vessel first with a parallel anastomosis method when employing multiple sequential bypass grafting. This improves hemodynamic stability and energy efficiency, according to a computational fluid dynamics model.
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17
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Condemi F, Campisi S, Viallon M, Croisille P, Avril S. Relationship Between Ascending Thoracic Aortic Aneurysms Hemodynamics and Biomechanical Properties. IEEE Trans Biomed Eng 2020; 67:949-956. [DOI: 10.1109/tbme.2019.2924955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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18
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Gooch KJ, Firstenberg MS, Shrefler BS, Scandling BW. Biomechanics and Mechanobiology of Saphenous Vein Grafts. J Biomech Eng 2019; 140:2666246. [PMID: 29222565 DOI: 10.1115/1.4038705] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Indexed: 11/08/2022]
Abstract
Within several weeks of use as coronary artery bypass grafts (CABG), saphenous veins (SV) exhibit significant intimal hyperplasia (IH). IH predisposes vessels to thrombosis and atherosclerosis, the two major modes of vein graft failure. The fact that SV do not develop significant IH in their native venous environment coupled with the rapidity with which they develop IH following grafting into the arterial circulation suggests that factors associated with the isolation and preparation of SV and/or differences between the venous and arterial environments contribute to disease progression. There is strong evidence suggesting that mechanical trauma associated with traditional techniques of SV preparation can significantly damage the vessel and might potentially reduce graft patency though modern surgical techniques reduces these injuries. In contrast, it seems possible that modern surgical technique, specifically endoscopic vein harvest, might introduce other mechanical trauma that could subtly injure the vein and perhaps contribute to the reduced patency observed in veins harvested using endoscopic techniques. Aspects of the arterial mechanical environment influence remodeling of SV grafted into the arterial circulation. Increased pressure likely leads to thickening of the medial wall but its role in IH is less clear. Changes in fluid flow, including increased average wall shear stress, may reduce IH while disturbed flow likely increase IH. Nonmechanical stimuli, such as exposure to arterial levels of oxygen, may also have a significant but not widely recognized role in IH. Several potentially promising approaches to alter the mechanical environment to improve graft patency are including extravascular supports or altered graft geometries are covered.
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Affiliation(s)
- Keith J Gooch
- Department of Biomedical Engineering, The Ohio State University, 290 Bevis Hall 1080 Carmack Drive, Columbus, OH 43210.,Davis Heart Lung Research Institute, The Ohio State University, Columbus, OH 43210 e-mail:
| | - Michael S Firstenberg
- Surgery and Integrative Medicine, Northeast Ohio Medical Universities, Akron, OH 44309
| | - Brittany S Shrefler
- Department of Internal Medicine, The Ohio State University, Columbus, OH 43210
| | - Benjamin W Scandling
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210
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19
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Matsuura K, Jin WW, Liu H, Matsumiya G. Computational fluid dynamic study of different incision length of coronary artery bypass grafting in a native coronary stenosis model. J Thorac Dis 2019; 11:393-399. [PMID: 30962982 DOI: 10.21037/jtd.2019.01.35] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background The objective of this study was to evaluate hemodynamic patterns in end-side coronary artery bypass grafting with different anastomosis length by computational fluid dynamic study in the native coronary stenosis model. Methods The fluid dynamic computations were carried out using ANSYS CFX. Incision length was set to be 2, 4, 6, 8, 10 mm. The angle between the two blood vessels corresponded to the length of the incision. Native vessels were set to be 90% stenosis. The radius of both native and graft vessels was set to be 2 mm. The inlet boundary condition was set by the sample of the transient time flow which was measured intraoperatively. Results The energy efficiency was higher and energy loss was lower when the anastomosis length was longer until 8 mm. However, energy efficiency was lowest and energy loss was highest in the 10-mm model. In the 10-mm incision model, the streamline showed the scanty bypass flow in the bottom. Vortex showed that only 10-mm model showed the vortex just distal to the stenosis in the native inlet, and more vortex in native outlet than other length models. The oscillatory shear index (OSI) was higher in the outlet top in all models. And only 10-mm model showed high oscillatory index just distal to the stenosis. Conclusions In the end-side anastomosis, an anastomosis length of 8 mm was the ideal length with less flow complexity, low OSI, and less energy loss and high energy efficiency in the native 90% stenosis model.
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Affiliation(s)
- Kaoru Matsuura
- Department of Cardiovascular Surgery, Chiba University Hospital, Chiba, Japan
| | - Wei Wei Jin
- Graduate School of Engineering, Chiba University, Chiba, Japan.,Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Hao Liu
- Graduate School of Engineering, Chiba University, Chiba, Japan
| | - Goro Matsumiya
- Department of Cardiovascular Surgery, Chiba University Hospital, Chiba, Japan
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20
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Kolli KK, Min JK. Image-Based Computational Fluid Dynamic Analysis for Surgical Planning of Sequential Grafts in Coronary Artery Bypass Grafting. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:4893-4896. [PMID: 30441440 DOI: 10.1109/embc.2018.8513435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Coronary bypass grafting (CABG) is a surgical procedure for anastomosing small grafts to the coronary vessels. The bypass graft bridges the occluded or diseased coronary artery, allowing sufficient blood flow to deliver oxygen and nutrients to the heart muscles. Patient-specific (PS) anatomy obtained from coronary computed tomography angiography (CCTA) was used to generate a 3D aorto-coronary model (pre-surgery). Additionally, three more models with idealized grafts (individual and sequential grafts), were created using Boolean operations to represent post-surgery configuration. Fractional flow reserve (FFR) and wall shear stress (WSS) were estimated from the computational fluid dynamics (CFD). The pre-surgical FFR values for all the three left coronary arteries were significant (FFR<.80). The flow was restored (FFR>0.80) distal to stenosis in all the three post- surgical idealized graft models. Peak WSS values of 468, 336 and 295 dynes/cm2 were observed at the toe of the individual end-to-side anastomosis for the three graft models. More importantly, low WSS (< 100 dynes/cm2) prevails at the heel and the walls opposite to the anastomosis in the sequential graft models. The prevailing low WSS at the heel and the wall bed opposite to anastomosis, in a sequential graft model, reduces restenosis rates and promotes a uniform hemodynamic environment for a better long-term patency of the graft. PS- CFD simulations based on CCTA can be helpful in assessing the hemodynamic parameters of graft models for optimal surgical planning.
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21
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Numerical and Experimental Investigation of Novel Blended Bifurcated Stent Grafts with Taper to Improve Hemodynamic Performance. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2018; 2018:8054850. [PMID: 30271457 PMCID: PMC6151236 DOI: 10.1155/2018/8054850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/17/2018] [Accepted: 07/29/2018] [Indexed: 11/26/2022]
Abstract
The typical helical flow within the human arterial system is widely used when designing cardiovascular devices, as this helical flow can be generated using the “crossed limbs” strategy of the bifurcated stent graft (BSG) and enhanced by the tapered structure of arteries. Here, we propose the use of a deflected blended bifurcated stent graft (BBSG) with various tapers, using conventional blended BSGs with the same degree of taper as a comparison. Hemodynamic performances, including helical strength and wall shear stress- (WSS-) based indicators, were assessed. Displacement forces that may induce stent-graft migration were assessed using numerical simulations and in vitro experiments. The results showed that as the taper increased, the displacement force, helicity strength, and time-averaged wall shear stress (TAWSS) within the iliac grafts increased, whereas the oscillating shear index (OSI) and relative residence time (RRT) gradually decreased for both types of BBSGs. With identical tapers, deflected BBSGs, compared to conventional BBSGs, exhibited a wider helical structure and lower RRT on the iliac graft and lower displacement force; however, there were no differences in hemodynamic indicators. In summary, the presence of tapering facilitated helical flow and produced better hemodynamic performance but posed a higher risk of graft migration. Conventional and deflected BBSGs with taper might be the two optimal configurations for endovascular aneurysm repair, given the helical flow. The deflected BBSG provides a better configuration, compared to the conventional BBSG, when considering the reduction of migration risk.
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22
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Radke D, Jia W, Sharma D, Fena K, Wang G, Goldman J, Zhao F. Tissue Engineering at the Blood-Contacting Surface: A Review of Challenges and Strategies in Vascular Graft Development. Adv Healthc Mater 2018; 7:e1701461. [PMID: 29732735 PMCID: PMC6105365 DOI: 10.1002/adhm.201701461] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/09/2018] [Indexed: 12/14/2022]
Abstract
Tissue engineered vascular grafts (TEVGs) are beginning to achieve clinical success and hold promise as a source of grafting material when donor grafts are unsuitable or unavailable. Significant technological advances have generated small-diameter TEVGs that are mechanically stable and promote functional remodeling by regenerating host cells. However, developing a biocompatible blood-contacting surface remains a major challenge. The TEVG luminal surface must avoid negative inflammatory responses and thrombogenesis immediately upon implantation and promote endothelialization. The surface has therefore become a primary focus for research and development efforts. The current state of TEVGs is herein reviewed with an emphasis on the blood-contacting surface. General vascular physiology and developmental challenges and strategies are briefly described, followed by an overview of the materials currently employed in TEVGs. The use of biodegradable materials and stem cells requires careful control of graft composition, degradation behavior, and cell recruitment ability to ensure that a physiologically relevant vessel structure is ultimately achieved. The establishment of a stable monolayer of endothelial cells and the quiescence of smooth muscle cells are critical to the maintenance of patency. Several strategies to modify blood-contacting surfaces to resist thrombosis and control cellular recruitment are reviewed, including coatings of biomimetic peptides and heparin.
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Affiliation(s)
- Daniel Radke
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Wenkai Jia
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Dhavan Sharma
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Kemin Fena
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Guifang Wang
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Jeremy Goldman
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
| | - Feng Zhao
- Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, U.S
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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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Podemska-Jedrzejczak Z, Malinska A, Sujka-Kordowska P, Nowicki M, Puslecki M, Jemielity M, Perek B. Vascular restenosis in coronary artery bypass grafting might be associated with VEGF-C/VEGFR-3 signaling pathway. Heart Vessels 2018; 33:1106-1120. [PMID: 29557990 PMCID: PMC6096743 DOI: 10.1007/s00380-018-1158-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 03/16/2018] [Indexed: 11/29/2022]
Abstract
The vascular endothelial growth factor (VEGF) family of peptides and caveolins (CAVs) are reported to contribute, in early graft failure in patients, a coronary artery bypass grafting (CABG). To investigate the possible association of ultimate luminal occlusion to VEGFs and CAVs expression, a functional analysis (based on the molecular biology, bioinformatics, histology, and clinical studies) was performed. Twenty-four hundred and sixty-eight CABG patients diagnosed with multivessel stable coronary artery disease (CAD) were enrolled into prospective study and assigned to two subgroups: double- and triple-vessel CAD subjects. Distal parts of all the harvested saphenous vein (SV) and internal thoracic artery (ITA) segments were used for further tests. ITA graft failure did not differ between double-vessel and triple-vessel CAD patients. The number of SV occlusions was significantly higher in triple-vessel CAD subjects. The microarray analysis performed on SV and ITA samples obtained exclusively from triple-vessel CAD patients who developed early graft occlusion revealed 383 genes with increased and 301 genes with decreased expression in ITA samples as compared to SV grafts. This was followed by functional analysis of ‘blood vessel development’ group of genes. Average VEGF-C expression in ITA grafts was higher than in corresponding SV grafts; FLT4 expression was significantly higher in SV than in ITA transplants. VEGFR-3 and CAV3 expression demonstrated immunohistochemically in SMCs of the tunica media of SV grafts predicted their early restenosis in triple-vessel CAD patients. CAV2 protein expression in SMCs of ITA grafts indicated the risk of early graft failure both in double-vessel and triple-vessel CAD subjects.
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Affiliation(s)
- Zuzanna Podemska-Jedrzejczak
- Department of Histology and Embryology, Poznan University of Medical Sciences, Swiecickiego 6 St, 60-781, Poznan, Poland
| | - Agnieszka Malinska
- Department of Histology and Embryology, Poznan University of Medical Sciences, Swiecickiego 6 St, 60-781, Poznan, Poland.,Department of Anatomy and Histology, University of Zielona Gora, Zyty 28 St, 65-046, Zielona Gora, Poland
| | - Patrycja Sujka-Kordowska
- Department of Histology and Embryology, Poznan University of Medical Sciences, Swiecickiego 6 St, 60-781, Poznan, Poland. .,Department of Anatomy and Histology, University of Zielona Gora, Zyty 28 St, 65-046, Zielona Gora, Poland.
| | - Michal Nowicki
- Department of Histology and Embryology, Poznan University of Medical Sciences, Swiecickiego 6 St, 60-781, Poznan, Poland
| | - Mateusz Puslecki
- Department of Cardiac Surgery and Transplantology, Poznan University of Medical Sciences, Dluga 1/2 St, 60-101, Poznan, Poland
| | - Marek Jemielity
- Department of Cardiac Surgery and Transplantology, Poznan University of Medical Sciences, Dluga 1/2 St, 60-101, Poznan, Poland
| | - Bartlomiej Perek
- Department of Cardiac Surgery and Transplantology, Poznan University of Medical Sciences, Dluga 1/2 St, 60-101, Poznan, Poland
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Computational fluid dynamics study of the end-side and sequential coronary artery bypass anastomoses in a native coronary occlusion model†. Interact Cardiovasc Thorac Surg 2017; 26:583-589. [DOI: 10.1093/icvts/ivx376] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 10/27/2017] [Indexed: 11/14/2022] Open
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26
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Guerciotti B, Vergara C, Ippolito S, Quarteroni A, Antona C, Scrofani R. A computational fluid–structure interaction analysis of coronary Y-grafts. Med Eng Phys 2017; 47:117-127. [DOI: 10.1016/j.medengphy.2017.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/12/2017] [Accepted: 05/16/2017] [Indexed: 10/19/2022]
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27
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Shintani Y, Iino K, Yamamoto Y, Kato H, Takemura H, Kiwata T. Analysis of Computational Fluid Dynamics and Particle Image Velocimetry Models of Distal-End Side-to-Side and End-to-Side Anastomoses for Coronary Artery Bypass Grafting in a Pulsatile Flow. Circ J 2017; 82:110-117. [PMID: 28824030 DOI: 10.1253/circj.cj-17-0381] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Intimal hyperplasia (IH) is a major cause of graft failure. Hemodynamic factors such as stagnation and disturbed blood flow are involved in IH formation. The aim of this study is to perform a comparative analysis of distal-end side-to-side (deSTS) and end-to-side (ETS) anastomoses using computational fluid dynamics (CFD) after validating the results via particle image velocimetry (PIV).Methods and Results:We investigated the characteristics of our target flow fields using CFD under steady and pulsatile flows. CFD via PIV under steady flow in a 10-times-actual-size model was validated. The CFD analysis revealed a recirculation zone in the heel region in the deSTS and ETS anastomoses and at the distal end of the graft, and just distal to the toe of the host artery in the deSTS anastomoses. The recirculation zone sizes changed with the phase shift. We found regions of low wall shear stress and high oscillating shear index in the same areas. The PIV and CFD results were similar. CONCLUSIONS It was demonstrated that the hemodynamic characteristics of CFD and PIV is the difference between the deSTS and ETS anastomoses; that is, the deSTS flow peripheral to the distal end of the graft, at the distal end and just distal to the toe of the host artery is involved in the IH formation.
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Affiliation(s)
- Yoshiko Shintani
- Department of Thoracic, Cardiovascular and General Surgery, Kanazawa University
| | - Kenji Iino
- Department of Thoracic, Cardiovascular and General Surgery, Kanazawa University
| | - Yoshitaka Yamamoto
- Department of Thoracic, Cardiovascular and General Surgery, Kanazawa University
| | - Hiroki Kato
- Department of Thoracic, Cardiovascular and General Surgery, Kanazawa University
| | - Hirofumi Takemura
- Department of Thoracic, Cardiovascular and General Surgery, Kanazawa University
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LI LANLAN, LIU YOUJUN, ZHAO XI, MAO BOYAN, ZHANG HUIXIA. IMPACT OF COMPETITIVE FLOW ON HEMODYNAMICS OF LIMA-LAD GRAFTING WITH DIFFERENT STENOSIS: A NUMERICAL STUDY. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417500403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background and Aims: Competitive flow exists in the native coronary artery when using artery graft in the coronary artery bypass graft (CABG), and it is a major factor affecting the long-term patency of the arterial grafts. The purpose of this study is to investigate the effects of the competitive flow on hemodynamic characteristics of left internal mammary artery (LIMA). Materials and methods: Seven three-dimensional (3D) LIMA-left anterior decending (LAD) grafting models with different diameter stenoses at the trunk of LAD were reconstructed, including 25%, 40%, 50%, 60%, 75%, 90% and 100%. The boundary conditions of these models were provided by the same lumped parameter model (LPM; 0D sub-model) of cardiovascular circulatory system, which is based on 0D/3D coupling method. Results: The simulation results show that competitive flow decreases when the stenosis rate increases and backflow exists in LIMA during systole when the degree of stenosis is below 50%; the wall shear stress (WSS) of the graft increases from 0.85[Formula: see text]Pa to 1.79[Formula: see text]Pa with the increase of the native coronary stenosis degree, while the oscillatory shear index (OSI) decreases from 0.1557 to 0.00213. Conclusions: Competitive flow may produce adverse hemodynamic effects on artery graft, especially when the stenosis degree is below 50%, competitive flow will significantly lead the long-term patency of the artery graft worse because of the backflow, low WSS and high OSI, and the effect of OSI is more obvious than WSS.
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Affiliation(s)
- LANLAN LI
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District Beijing 100124, P. R. China
| | - YOUJUN LIU
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District Beijing 100124, P. R. China
| | - XI ZHAO
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District Beijing 100124, P. R. China
| | - BOYAN MAO
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District Beijing 100124, P. R. China
| | - HUIXIA ZHANG
- College of Life Science and Bio-Engineering, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District Beijing 100124, P. R. China
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29
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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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Improvement of hemodynamic performance using novel helical flow vena cava filter design. Sci Rep 2017; 7:40724. [PMID: 28112186 PMCID: PMC5256025 DOI: 10.1038/srep40724] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 12/09/2016] [Indexed: 12/25/2022] Open
Abstract
We propose a vena cava filter in which helical flow is created in the filter’s working zone to minimize filter blockage by trapped clots and facilitate the lysis of trapped clots. To validate this new design, we compared five helical flow inducers with different thread pitches in terms of blood flow patterns in the filter. The vena cava was reconstructed based on computed tomography images. Both the numerical simulation and in vitro experiment revealed that the helical flow inducer can effectively create a helical flow in the vessel, thereby subduing the filter structure’s adverse disruption to blood flow, and increasing flow-induced shear stress in the filter center. In addition, the smaller thread pitch helical flow inducer reduced the oscillating shear index and relative residence time on the vessel wall. Moreover, we observed that the helical flow inducer in the vena cava could induce flow rotation both in clockwise and counterclockwise directions. In conclusion, the new design of the filter with the smaller thread pitch inducer is advantageous over the traditional filter in terms of improving local hemodynamics, which may reduce thrombosis build-up after deployment.
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31
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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: 54] [Impact Index Per Article: 6.8] [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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32
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Bioinspired helical graft with taper to enhance helical flow. J Biomech 2016; 49:3643-3650. [DOI: 10.1016/j.jbiomech.2016.09.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 09/09/2016] [Accepted: 09/19/2016] [Indexed: 11/23/2022]
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33
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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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Pashneh-Tala S, MacNeil S, Claeyssens F. The Tissue-Engineered Vascular Graft-Past, Present, and Future. TISSUE ENGINEERING PART B-REVIEWS 2015; 22:68-100. [PMID: 26447530 PMCID: PMC4753638 DOI: 10.1089/ten.teb.2015.0100] [Citation(s) in RCA: 449] [Impact Index Per Article: 49.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiovascular disease is the leading cause of death worldwide, with this trend predicted to continue for the foreseeable future. Common disorders are associated with the stenosis or occlusion of blood vessels. The preferred treatment for the long-term revascularization of occluded vessels is surgery utilizing vascular grafts, such as coronary artery bypass grafting and peripheral artery bypass grafting. Currently, autologous vessels such as the saphenous vein and internal thoracic artery represent the gold standard grafts for small-diameter vessels (<6 mm), outperforming synthetic alternatives. However, these vessels are of limited availability, require invasive harvest, and are often unsuitable for use. To address this, the development of a tissue-engineered vascular graft (TEVG) has been rigorously pursued. This article reviews the current state of the art of TEVGs. The various approaches being explored to generate TEVGs are described, including scaffold-based methods (using synthetic and natural polymers), the use of decellularized natural matrices, and tissue self-assembly processes, with the results of various in vivo studies, including clinical trials, highlighted. A discussion of the key areas for further investigation, including graft cell source, mechanical properties, hemodynamics, integration, and assessment in animal models, is then presented.
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Affiliation(s)
- Samand Pashneh-Tala
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
| | - Sheila MacNeil
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
| | - Frederik Claeyssens
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
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Fabrication of poly (L-lactic acid)/gelatin composite tubular scaffolds for vascular tissue engineering. Int J Biol Macromol 2015; 72:1048-55. [PMID: 25316418 DOI: 10.1016/j.ijbiomac.2014.09.058] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/03/2014] [Accepted: 09/26/2014] [Indexed: 11/21/2022]
Abstract
The in vitro fabrication of fully functional 3D vascular tissue construct represents one of the most fundamental challenges in vascular tissue engineering. Polymer blending is an effective method for developing, desirable bio-composites for tissue engineering. This study employs the blending of desired characteristics of a synthetic polymer, poly (L-lactic acid) (PLLA) and a biopolymer, gelatin for enhancing cell adhesion sites. Aligned and random PLLA/gelatin nanofibers were fabricated using electrospinning technique. Morphological and chemical characterization of the nanofibrous scaffolds was carried out and the size of fibers ranged from 100 to 500 nm. The SEM, fluorescent staining and viability assays revealed an increase in viability and proliferation of Human Umbilical Vein Endothelial Cells (HUVECs) and Smooth Muscle Cells (SMCs) proportional to gelatin content. The aligned fiber morphology helps cells to orient and elongate along their long axis. Thus the results were suggestive of the fact that topographically aligned nanofibrous scaffolds control cellular organization and possibly provide a good support for achieving the vital organization and physical properties of blood vessel.
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36
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XU LIFU, HUANG XINSHENG, TA NA, RAO ZHUSHI, TIAN JIABIN. FINITE ELEMENT MODELING OF THE HUMAN COCHLEA USING FLUID–STRUCTURE INTERACTION METHOD. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415500396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, a 3D finite element (FE) model of human cochlea is developed. This passive model includes the structure of oval window, round window, basilar membrane (BM) and cochlear duct which is filled with fluid. Orthotropic material property of the BM is varying along its length. The fluid–structure interaction (FSI) method is used to compute the responses in the cochlea. In particular, the viscous fluid element is adopted for the first time in the cochlear FE model, so that the effects of shear viscosity in the fluid are considered. Results on the cochlear impedance, BM response and intracochlear pressure are obtained. The intracochlear pressure includes the scala vestibule and scala tympani pressure are extracted and used to calculate the transfer functions from equivalent ear canal pressures to scala pressures. The reasonable agreements between the model results and the experimental data in the literature prove the validity of the cochlear model for simulating sound transmission in the cochlea. Moreover, this model predicted the transfer function from equivalent ear canal pressures to scala pressures which is the input to the cochlear partition.
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Affiliation(s)
- LIFU XU
- Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - XINSHENG HUANG
- Department of Otorhinolaryngology, Zhongsan Hospital, Fudan University, Shanghai 200032, P. R. China
| | - NA TA
- Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - ZHUSHI RAO
- Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - JIABIN TIAN
- Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
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Bioengineering Strategies for Polymeric Scaffold for Tissue Engineering an Aortic Heart Valve: An Update. Int J Artif Organs 2014; 37:651-67. [DOI: 10.5301/ijao.5000339] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2014] [Indexed: 12/17/2022]
Abstract
The occurrence of dysfunctional aortic valves is increasing every year, and current replacement heart valves, although having been shown to be clinically successful, are only short-term solutions and suffer from many agonizing long-term drawbacks. The tissue engineering of heart valves is recognized as one of the most promising answers for aortic valve disease therapy, but overcoming current shortcomings will require multidisciplinary efforts. The use of a polymeric scaffold to guide the growth of the tissue is the most common approach to generate a new tissue for an aortic heart valve. However, optimizing the design of the scaffold, in terms of biocompatibility, surface morphology for cell attachments and the correct rate of degradation is critical in creating a viable tissue-engineered aortic heart valve. This paper highlights the bioengineering strategies that need to be followed to construct a polymeric scaffold of sufficient mechanical integrity, with superior surface morphologies, that is capable of mimicking the valve dynamics in vivo. The current challenges and future directions of research for creating tissue-engineered aortic heart valves are also discussed.
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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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Ji J, Yang JA, He X, Ling WP, Chen XL. Cardiac-targeting transfection of tissue-type plasminogen activator gene to prevent the graft thrombosis and vascular anastomotic restenosis after coronary bypass. Thromb Res 2014; 134:440-8. [PMID: 24968958 DOI: 10.1016/j.thromres.2014.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/07/2014] [Accepted: 04/17/2014] [Indexed: 11/19/2022]
Abstract
AIM To observe the tissue-type plasminogen activator gene (t-PA) plasmid packaged with albumin nanoparticles crosslinked to albumin ultrasound microbubbles for targeting transfection to myocardium to prevent the graft thrombosis and vascular anastomotic restenosis after coronary bypass. METHODS A dog model of coronary bypass using the autoallergic saphenous vein as the graft was made. A highly expressive t-PA gene plasmid packaged with albumin nanoparticles crosslinked to albumin ultrasound microbubbles was constructed. Targeting myocardial transfection was performed with this gene vector under the aid of therapeutic ultrasound(1MHz, 1.5 w/cm2, 6minutes, intravenously) after the bypass. The expression of t-PA in myocardium was detected with a multiclonal antibody to t-PA by the indirect immunohistochemical method. Venous blood t-PA and D-dimer contents were tested before and 1, 2 and 4weeks after the operation. The effects of this gene vector on thrombosis of the grafts and the coronary intimal hyperplasia around the anastomotic stoma were observed using a routine pathological examination, a morphometry for intimal thickness and area and the immuno-histochemical stain with a monoclonal antibody to PCNA for estimating the intimal SMC proliferation. RESULTS The effective expression of t-PA protein by myocardium was obtained, followed by the persistent raises of blood t-PA and D-dimer 1, 2 and 4weeks after the transfection. Thrombosis of the grafts was successfully restrained. The expression of PCNA by coronary intimal vSMCs and intimal hyperplasia were remarkablely reduced. CONCLUSION This t-PA gene targeting vector could be used to prevent the dog thrombosis, which provided the experimental identification for prevention on human thrombotic diseases.
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Affiliation(s)
- Jun Ji
- Department of Pathology, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen 518020, Guangdong, China
| | - Jian-An Yang
- Cardiovascular Surgery, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen 518020, Guangdong, China.
| | - Xia He
- Department of Pathology, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen 518020, Guangdong, China
| | - Wen-Ping Ling
- Department of Pathology, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen 518020, Guangdong, China
| | - Xiao-Ling Chen
- Department of Pathology, Shenzhen Sun Yat-Sen Cardiovascular Hospital, Shenzhen 518020, Guangdong, China
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Su B, Zhong L, Wang XK, Zhang JM, Tan RS, Allen JC, Tan SK, Kim S, Leo HL. Numerical simulation of patient-specific left ventricular model with both mitral and aortic valves by FSI approach. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2014; 113:474-482. [PMID: 24332277 DOI: 10.1016/j.cmpb.2013.11.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 10/25/2013] [Accepted: 11/18/2013] [Indexed: 06/03/2023]
Abstract
Intraventricular flow is important in understanding left ventricular function; however, relevant numerical simulations are limited, especially when heart valve function is taken into account. In this study, intraventricular flow in a patient-specific left ventricle has been modelled in two-dimension (2D) with both mitral and aortic valves integrated. The arbitrary Lagrangian-Eulerian (ALE) approach was employed to handle the large mesh deformation induced by the beating ventricular wall and moving leaflets. Ventricular wall deformation was predefined based on MRI data, while leaflet dynamics were predicted numerically by fluid-structure interaction (FSI). Comparisons of simulation results with in vitro and in vivo measurements reported in the literature demonstrated that numerical method in combination with MRI was able to predict qualitatively the patient-specific intraventricular flow. To the best of our knowledge, we are the first to simulate patient-specific ventricular flow taking into account both mitral and aortic valves.
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Affiliation(s)
- Boyang Su
- Biofluid Mechanics Research Laboratory, 2 Engineering Drive 3, Department of Bioengineering, National University of Singapore, 117576 Singapore, Singapore; Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore, Mistri Wing 17, 3rd Hospital Avenue, 168752 Singapore, Singapore
| | - Liang Zhong
- Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore, Mistri Wing 17, 3rd Hospital Avenue, 168752 Singapore, Singapore; Duke-NUS Graduate Medical School Singapore, 8 College Road, 169857 Singapore, Singapore.
| | - Xi-Kun Wang
- Maritime Research Centre, Nanyang Technological University, Singapore
| | - Jun-Mei Zhang
- Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore, Mistri Wing 17, 3rd Hospital Avenue, 168752 Singapore, Singapore
| | - Ru San Tan
- Cardiac Mechanics Engineering and Physiology Unit, National Heart Centre Singapore, Mistri Wing 17, 3rd Hospital Avenue, 168752 Singapore, Singapore; Duke-NUS Graduate Medical School Singapore, 8 College Road, 169857 Singapore, Singapore
| | - John Carson Allen
- Duke-NUS Graduate Medical School Singapore, 8 College Road, 169857 Singapore, Singapore
| | - Soon Keat Tan
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore
| | - Sangho Kim
- Department of Bioengineering, National University of Singapore, Singapore
| | - Hwa Liang Leo
- Department of Bioengineering, National University of Singapore, Singapore
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Carniel EL, Gramigna V, Fontanella CG, Frigo A, Stefanini C, Rubini A, Natali AN. Characterization of the anisotropic mechanical behaviour of colonic tissues: experimental activity and constitutive formulation. Exp Physiol 2014; 99:759-71. [PMID: 24486449 DOI: 10.1113/expphysiol.2013.076091] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The aim was to investigate the biomechanical behaviour of colonic tissues by a coupled experimental and numerical approach. The wall of the colon is composed of different tissue layers. Within each layer, different fibre families are distributed according to specific spatial orientations, which lead to a strongly anisotropic configuration. Accounting for the complex histology of the tissues, mechanical tests must be planned and designed to evaluate the behaviour of the colonic wall in different directions. Uni-axial tensile tests were performed on tissue specimens from 15 fresh pig colons, accounting for six different loading directions (five specimens for each loading direction). The next step of the investigation was to define an appropriate constitutive framework and develop a procedure for identification of the constitutive parameters. A specific hyperelastic formulation was developed that accounted for the multilayered conformation of the colonic wall and the fibre-reinforced configuration of the tissues. The parameters were identified by inverse analyses of the mechanical tests. The comparison of model results with experimental data, together with the evaluation of satisfaction of material thermomechanics principles, confirmed the reliability of the analysis developed. This work forms the basis for more comprehensive activities that aim to provide computational tools for the interpretation of surgical procedures that involve the gastrointestinal tract, considering the specific biomedical devices adopted.
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Affiliation(s)
- E L Carniel
- Department of Industrial Engineering Centre of Mechanics of Biological Materials
| | - V Gramigna
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | | | - A Frigo
- Department of Industrial Engineering Centre of Mechanics of Biological Materials
| | - C Stefanini
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - A Rubini
- Centre of Mechanics of Biological Materials Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - A N Natali
- Department of Industrial Engineering Centre of Mechanics of Biological Materials
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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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Wang C, Baker BM, Chen CS, Schwartz MA. Endothelial cell sensing of flow direction. Arterioscler Thromb Vasc Biol 2013; 33:2130-6. [PMID: 23814115 DOI: 10.1161/atvbaha.113.301826] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Atherosclerosis-prone regions of arteries are characterized by complex flow patterns where the magnitude of shear stress is low and direction rapidly changes, termed disturbed flow. How endothelial cells sense flow direction and how it impacts inflammatory effects of disturbed flow are unknown. We therefore aimed to understand how endothelial cells respond to changes in flow direction. APPROACH AND RESULTS Using a recently developed flow system capable of changing flow direction to any angle, we show that responses of aligned endothelial cells are determined by flow direction relative to their morphological and cytoskeletal axis. Activation of the atheroprotective endothelial nitric oxide synthase pathway is maximal at 180° and undetectable at 90°, whereas activation of proinflammatory nuclear factor-κB is maximal at 90° and undetectable at 180°. Similar effects were observed in randomly oriented cells in naive monolayers subjected to onset of shear. Cells aligned on micropatterned substrates subjected to oscillatory flow were also examined. In this system, parallel flow preferentially activated endothelial nitric oxide synthase and production of nitric oxide, whereas perpendicular flow preferentially activated reactive oxygen production and nuclear factor-κB. CONCLUSIONS These data show that the angle between flow and the cell axis defined by their shape and cytoskeleton determines endothelial cell responses. The data also strongly suggest that the inability of cells to align in low and oscillatory flow is a key determinant of the resultant inflammatory activation.
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Affiliation(s)
- Chong Wang
- Robert M Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA
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Karimi A, Navidbakhsh M, Shojaei A, Faghihi S. Measurement of the uniaxial mechanical properties of healthy and atherosclerotic human coronary arteries. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:2550-4. [PMID: 23623067 DOI: 10.1016/j.msec.2013.02.016] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/17/2013] [Accepted: 02/10/2013] [Indexed: 01/19/2023]
Abstract
Atherosclerosis is a common arterial disease which alters the stiffness of arterial wall. Arterial stiffness is related to many cardiovascular diseases. In this investigation, maximum stress and strain as well as physiological and maximum elastic modulus of 22 human coronary arteries are measured. In addition, the force-displacement diagram of human coronary artery is obtained to discern the alterations between the healthy and atherosclerotic arterial wall stiffness. The age of each specimen and its effect on the elastic modulus of human coronary arteries is also considered. Twenty-two human coronary arteries, including eight atherosclerotic and fourteen healthy arteries are excised within 5 hours post-mortem. Samples are mounted on a tensile-testing machine and force is applied until breakage occurs. Elastic modulus coefficient of each specimen is calculated to compare the stiffness of healthy and atherosclerotic coronary arteries. The results show that the atherosclerotic arteries bear 44.55% more stress and 34.61% less strain compared to the healthy ones. The physiological and maximum elastic moduli of healthy arteries are 2.53 and 2.91 times higher than that of atherosclerotic arteries, respectively. The age of specimens show no correlation with the arterial wall stiffness. A combination of biomechanics and mathematics is used to characterize the mechanical properties of human coronary arteries. These results could be utilized to understand the extension and rupture mechanism of coronary arteries and has implications for interventions and surgeries, including balloon-angioplasty, bypass, and stenting.
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Affiliation(s)
- Alireza Karimi
- Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology, Tehran 14965/161, Iran
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