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Yang J, Bai Z, Song C, Ding H, Chen M, Sun J, Liu X. Research on the Internal Flow Field of Left Atrial Appendage and Stroke Risk Assessment with Different Blood Models. Bioengineering (Basel) 2023; 10:944. [PMID: 37627830 PMCID: PMC10451249 DOI: 10.3390/bioengineering10080944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/23/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
Extant clinical research has underscored that patients suffering from atrial fibrillation (AF) bear an elevated risk for stroke, predominantly driven by the formation of thrombus in the left atrial appendage (LAA). As such, accurately identifying those at an increased risk of thrombosis becomes paramount to facilitate timely and effective treatment. This study was designed to shed light on the mechanisms underlying thrombus formation in the LAA by employing three-dimensional (3D) left atrium (LA) models of AF patients, which were constructed based on Computed Tomography (CT) imaging. The distinct benefits of Computational Fluid Dynamics (CFD) were leveraged to simulate the blood flow field within the LA, using three distinct blood flow models, both under AF and sinus rhythm (SR) conditions. The potential risk of thrombus formation was evaluated by analyzing the Relative Residence Time (RRT) and Endothelial Cell Activation Potential (ECAP) values. The results gleaned from this study affirm that all three blood flow models align with extant clinical guidelines, thereby enabling an effective prediction of thrombosis risk. However, noteworthy differences emerged when comparing the intricacies of the flow field and thrombosis risk across the three models. The single-phase non-Newtonian blood flow model resulted in comparatively lower residence times for blood within the LA and lower values for the Oscillatory Shear Index (OSI), RRT, and ECAP within the LAA. These findings suggest a reduced thrombosis risk. Conversely, the two-phase non-Newtonian blood flow model exhibited a higher residence time for blood and elevated RRT value within the LAA, suggesting an increased risk for thrombosis.
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Affiliation(s)
- Jun Yang
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; (J.Y.); (Z.B.); (C.S.)
| | - Zitao Bai
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; (J.Y.); (Z.B.); (C.S.)
| | - Chentao Song
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; (J.Y.); (Z.B.); (C.S.)
| | - Huirong Ding
- Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200240, China; (H.D.); (M.C.)
| | - Mu Chen
- Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200240, China; (H.D.); (M.C.)
| | - Jian Sun
- Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200240, China; (H.D.); (M.C.)
| | - Xiaohua Liu
- School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai 200240, China
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2
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Dinh H, Vinuela F, Szeder V, Khatibi K, Mejia LP, Chien A. Reconstruction of carotid stenosis hemodynamics based on guidewire pressure data and computational modeling. Med Biol Eng Comput 2022; 60:1253-1268. [PMID: 35359199 DOI: 10.1007/s11517-021-02463-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 10/21/2021] [Indexed: 01/01/2023]
Abstract
A comparative analysis between intravascular guidewire-obtained and computational fluid dynamic (CFD) flow velocity and pressure data using simplified carotid stenosis models was performed. This information was used to evaluate the viability of using guidewire pressure data to provide inlet conditions for CFD flow, and to study the relationship between stenotic length and hemodynamic behavior. Carotid stenosis models differing in diameter and length were prepared and connected to a vascular pulsatile flow simulator. Time-dependent flow velocity and pressure measurements were taken by microcatheter guidewires and compared with CFD data. Guidewire and CFD-generated pressure profiles matched closely in all measurement locations. The guidewire was unable to reliably measure flow velocity at areas associated with higher CFD flow velocities (r = 0.92). CFD results showed that an increased length of stenosis generated expansive regions of elevated wall shear stress (WSS) within and distal to the stenosis. Low WSS was found immediately outside the stenosis outlet. An increase in stenotic length produced higher flow velocities with minimal lengthening of the distal high velocity flow jet due to faster dissipation of translational kinetic energy through turbulence. We found the accuracy of guidewire-obtained velocity measurements is limited to regions unaffected by disturbed flow. WSS and turbulence behavior distal to the stenosis may be important markers to evaluate the severity of atherosclerotic progression as a function of stenotic length.
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Affiliation(s)
- Huy Dinh
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA
| | - Fernando Vinuela
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA
| | - Viktor Szeder
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA
| | - Kasra Khatibi
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA
| | - Lucido Ponce Mejia
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA
| | - Aichi Chien
- Physics and Biology in Medicine Graduate Program, Division of Interventional Neuroradiology, Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, David Geffen UCLA School of Medicine, Los Angeles, USA.
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Numerical study on flow topology and hemodynamics in tortuous coronary artery with symmetrical and asymmetrical stenosis. Biocybern Biomed Eng 2021. [DOI: 10.1016/j.bbe.2020.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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4
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Szabo B, Tanczos B, Varga A, Barath B, Ghanem S, Rezsabek Z, Al-Smadi MW, Nemeth N. Micro-Rheological Changes of Red Blood Cells in the Presence of an Arterio-Venous Fistula or a Loop-Shaped Venous Graft in the Rat. Front Physiol 2020; 11:616528. [PMID: 33391035 PMCID: PMC7775550 DOI: 10.3389/fphys.2020.616528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/30/2020] [Indexed: 11/17/2022] Open
Abstract
Introduction: In case of kidney failure, hemodialysis is the primary kidney replacement technique. Several vascular access methods used for the therapy, one of which is the arterio-venous fistula (AVF). In the AVF, the blood flow is altered, which can elevate the mechanical stress on the red blood cells (RBCs). This can affect the RBC hemorheological properties, and it can further cause systemic changes. To lower the turbulence and shear stress, we performed a loop-shaped arterio-arterial venous interposition graft (loop-shaped graft) to compare its effect to the conventional AVF. Materials and Methods: Thirty male Wistar were used (permission registration Nr.: 25/2016/UDCAW). The animals were randomly divided into sham-operated, AVF, and loop groups (n = 10/each). The superficial inferior epigastric vein (SIEV) was used to create the AVF and the loop-shaped graft. Blood samples were taken before/after the surgery and at the 1st, 3rd, and 5th postoperative weeks. We measured hemorhelogical, hematological, and blood gas parameters. The microcirculation of the hind limbs was also monitored using Laser Doppler fluxmetry. Results: Hematocrit, RBC count, and hemoglobin decreased by the 1st postoperative week. The erythrocyte aggregation values significantly increased in the fistula group by the 5th week (6.43 ± 2.31 vs. 13.60; p < 0.0001; vs. before operation). At the postoperative 1st week in the loop group, the values showed a significant decrease in RBC deformability. During the maturation period, dominantly at the 5th week, all values were normalized. The operated hind limb’s skin microcirculation significantly increased in the sham and loop group by the 1st week (39 ± 10.57 vs. 73.93 ± 1.97 BFU, p < 0.01). This increase wasn’t observed in the fistula group probably due to a steal-effect. Conclusion: Unlike in the loop group, in the presence of the fistula, several rheological parameters have changed. The loop-shaped graft had only minimal impact on micro-rheological parameters.
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Affiliation(s)
- Balazs Szabo
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Debrecen, Debrecen, Hungary
| | - Bence Tanczos
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Debrecen, Debrecen, Hungary
| | - Adam Varga
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Debrecen, Debrecen, Hungary
| | - Barbara Barath
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Debrecen, Debrecen, Hungary
| | - Souleiman Ghanem
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Clinical Medicine, University of Debrecen, Debrecen, Hungary
| | - Zsofia Rezsabek
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Mohammad Walid Al-Smadi
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Norbert Nemeth
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Lakzian E, Akbarzadeh P. Numerical investigation of unsteady pulsatile Newtonian/non-Newtonian blood flow through curved stenosed arteries. Biomed Mater Eng 2019; 30:525-540. [PMID: 31771034 DOI: 10.3233/bme-191072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A numerical investigation of Newtonian/non-Newtonian unsteady pulsatile entry blood flow inside a 3D curved stenosed artery is presented. For considering the non-Newtonian effect (shear thinning or shear thickening behavior), the blood viscosity is characterized by the power-law model (Ostwald de Waele Equation). At the inlet of the artery, a realistic pulsatile waveform is utilized according to the experimental data reported by other researchers. This study belongs to the analysis of the curvature ratios, percentage and length ratio of stenosis, and blood thickening on hemodynamic characteristics of the flow. The results emphasize that the maximum wall shear stress happens near the stenosis neck and as expected, by decreasing the stenosis length, the maximum value of wall shear stress increases. In addition, the results indicate that the shear thickening fluid shows a more stable velocity profile rather than the shear thinning fluid flow.
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Affiliation(s)
- E Lakzian
- Faculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
| | - P Akbarzadeh
- Faculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran
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He F, Hua L, Gao LJ. A hemodynamic model with a seepage condition and fluid-structure interactions for blood flow in arteries with symmetric stenosis. J Biol Phys 2019; 45:183-192. [PMID: 31062132 DOI: 10.1007/s10867-019-09523-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 03/25/2019] [Indexed: 12/01/2022] Open
Abstract
To strengthen the detailed understanding of arterial stenosis, we construct a novel hemodynamic model. Frequently used symmetric stenosis is employed in this work. Being different from a traditional model, this numerical model adopts microcirculation resistance as an outlet boundary condition, which is called a seepage condition. Meanwhile, fluid-structure interactions are used in the numerical simulation considering the interrelationship of blood and arterial wall. Our results indicate that (i) the region upstream of stenosis experiences very high pressures during cardiac cycles, (ii) pressure drops much faster as the flow moves into the stenotic region, and (iii) high flow velocities and high shear stresses occur in the post-stenosis region. This work provides evidence that there is a strong effect of the function of microcirculation on stenosis. This contributes to evaluating potential stenotic behavior in arteries and is pivotal in guiding disease treatment.
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Affiliation(s)
- Fan He
- Department of Mechanics, School of Science, Beijing University of Civil Engineering and Architecture, Beijing, 100044, China.
| | - Lu Hua
- Key Laboratory of Clinical Trial Research in Cardiovascular Drugs, Ministry of Health, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Li-Jian Gao
- Key Laboratory of Clinical Trial Research in Cardiovascular Drugs, Ministry of Health, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
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7
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Discrete-Phase Modelling of an Asymmetric Stenosis Artery Under Different Womersley Numbers. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2019. [DOI: 10.1007/s13369-018-3391-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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8
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Ahamad NA, Kamangar S, Badruddin IA. The influence of curvature wall on the blood flow in stenosed artery: A computational study. Biomed Mater Eng 2018; 29:319-332. [DOI: 10.3233/bme-181734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- N. Ameer Ahamad
- Mathematics Department, Faculty of Science, University of Tabuk, Saudi Arabia
| | - Sarfaraz Kamangar
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Irfan Anjum Badruddin
- Department of Mechanical Engineering, College of Engineering, King Khalid University, Abha, 61421, Saudi Arabia
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Impact of spatial characteristics in the left stenotic coronary artery on the hemodynamics and visualization of 3D replica models. Sci Rep 2017; 7:15452. [PMID: 29133915 PMCID: PMC5684364 DOI: 10.1038/s41598-017-15620-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 10/25/2017] [Indexed: 12/31/2022] Open
Abstract
Cardiovascular disease has been the major cause of death worldwide. Although the initiation and progression mechanism of the atherosclerosis are similar, the stenotic characteristics and the corresponding medical decisions are different between individuals. In the present study, we performed anatomic and hemodynamic analysis on 8 left coronary arterial trees with 10 identified stenoses. A novel boundary condition method had been implemented for fast computational fluid dynamics simulations and patient-specific three-dimensional printed models had been built for visualizations. Our results suggested that the multiple spatial characteristics (curvature of the culprit vessel multiplied by an angle of the culprit's vessel to the upstream parent branch) could be an index of hemodynamics significance (r = -0.673, P-value = 0.033). and reduction of the maximum velocity from stenosis to downstream was found correlated to the FFRCT (r = 0.480, p = 0.160). In addition, 3D printed models could provide accurate replicas of the patient-specific left coronary arterial trees compare to virtual 3D models (r = 0.987, P-value < 0.001). Therefore, the visualization of the 3D printed models could help understand the spatial distribution of the stenoses and the hand-held experience could potentially benefit the educating and preparing of medical strategies.
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10
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Shi C, Zhang D, Cao K, Zhang T, Luo L, Liu X, Zhang H. A study of noninvasive fractional flow reserve derived from a simplified method based on coronary computed tomography angiography in suspected coronary artery disease. Biomed Eng Online 2017; 16:43. [PMID: 28407768 PMCID: PMC5391576 DOI: 10.1186/s12938-017-0330-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 03/17/2017] [Indexed: 01/14/2023] Open
Abstract
Background The invasive fractional flow reserve has been considered the gold standard for identifying ischaemia-related stenosis in patients with suspected coronary artery disease. Determining non-invasive FFR based on coronary computed tomographic angiography datasets using computational fluid dynamics tends to be a demanding process. Therefore, the diagnostic performance of a simplified method for the calculation of FFRCTA requires further evaluation. Objectives The aim of this study was to investigate the diagnostic performance of FFRCTA calculated based on a simplified method by referring to the invasive FFR in patient-specific coronary arteries and clinical decision-making. Methods Twenty-nine subjects included in this study underwent CCTA before undergoing clinically indicated invasive coronary angiography for suspected coronary artery disease. Pulsatile flow simulation and a novel boundary condition were used to obtain FFRCTA based on the CCTA datasets. The Pearson correlation, Bland–Altman plots and the diagnostic performance of FFRCTA and CCTA stenosis were analyzed by comparison to the invasive FFR reference standard. Ischaemia was defined as an FFR or FFRCTA ≤0.80, and anatomically obstructive CAD was defined as a CCTA stenosis >50%. Results FFRCTA and invasive FFR were well correlated (r = 0.742, P = 0.001). Slight systematic underestimation was found in FFRCTA (mean difference 0.03, standard deviation 0.05, P = 0.001). The area under the receiver-operating characteristic curve was 0.93 for FFRCTA and 0.75 for CCTA on a per-vessel basis. Per-patient accuracy, sensitivity and specificity were 79.3, 93.7 and 61.5%, respectively, for FFRCTA and 62.1, 87.5 and 30.7%, respectively, for CCTA. Per-vessel accuracy, sensitivity and specificity were 80.6, 94.1 and 68.4%, respectively, for FFRCTA and 61.6, 88.2 and 36.8%, respectively, for CCTA. Conclusions FFRCTA derived from pulsatile simulation with a simplified novel boundary condition was in good agreement with invasive FFR and showed better diagnostic performance compared to CCTA, suggesting that the simplified method has the potential to be an alternative and accurate way to assess the haemodynamic characteristics for coronary stenosis.
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Affiliation(s)
- Changzheng Shi
- Medical Imaging Center, The First Affiliated Hospital, Jinan University, 613 Huangpu W Ave, Tianhe District, Guangzhou, 510630, Guangdong Province, China
| | - Dong Zhang
- Medical Imaging Center, The First Affiliated Hospital, Jinan University, 613 Huangpu W Ave, Tianhe District, Guangzhou, 510630, Guangdong Province, China
| | - Kunlin Cao
- Research and Development Department, Shenzhen Keya Medical Technology, Co., Ltd., Longgang District, Shenzhen, 518116, Guangdong Province, China
| | - Tao Zhang
- Medical Imaging Center, The First Affiliated Hospital, Jinan University, 613 Huangpu W Ave, Tianhe District, Guangzhou, 510630, Guangdong Province, China
| | - Liangping Luo
- Medical Imaging Center, The First Affiliated Hospital, Jinan University, 613 Huangpu W Ave, Tianhe District, Guangzhou, 510630, Guangdong Province, China.
| | - Xin Liu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave. Xili University Town, Nanshan District, Shenzhen, 518055, Guangdong Province, China.
| | - Heye Zhang
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Ave. Xili University Town, Nanshan District, Shenzhen, 518055, Guangdong Province, China
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Samaee M, Tafazzoli-Shadpour M, Alavi H. Coupling of shear–circumferential stress pulses investigation through stress phase angle in FSI models of stenotic artery using experimental data. Med Biol Eng Comput 2016; 55:1147-1162. [DOI: 10.1007/s11517-016-1564-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 09/02/2016] [Indexed: 11/28/2022]
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12
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Peng C, Wang X, Xian Z, Liu X, Huang W, Xu P, Wang J. The Impact of the Geometric Characteristics on the Hemodynamics in the Stenotic Coronary Artery. PLoS One 2016; 11:e0157490. [PMID: 27310014 PMCID: PMC4911169 DOI: 10.1371/journal.pone.0157490] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/30/2016] [Indexed: 01/15/2023] Open
Abstract
The alterations of the hemodynamics in the coronary arteries, which result from patient-specific geometric significances are complex. The effect of the stenosis on the blood flow alteration had been wildly reported, but the combinational contribution from geometric factors required a comprehensive investigation to provide patient-specific information for diagnosis and assisting in the decision on the further treatment strategies. In the present study, we investigated the correlation between hemodynamic parameters and individual geometric factors in the patient-specific coronary arteries. Computational fluid dynamic simulations were performed on 22 patient-specific 3-dimensional coronary artery models that were reconstructed based on computed tomography angiography images. Our results showed that the increasing severity of the stenosis is associated with the increased maximum wall shear stress at the stenosis region (r = 0.752, P < 0.001). In contrast, the length of the recirculation zone has a moderate association with the curvature of the lesion segment (r = 0.505, P = 0.019) and the length of the lesions (r = 0.527, P = 0.064). Moreover, bifurcation in the coronary arteries is significantly correlated with the occurrence of recirculation, whereas the severity of distal stenosis demonstrated an effect on the alteration of the flow in the upstream bifurcation. These findings could serve as an indication for treatment planning and assist in prognosis evaluation.
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Affiliation(s)
- Changnong Peng
- Department of Cardiology, Shenzhen Sun Yat-Sen cardiovascular hospital, Shenzhen 518112, China
| | - Xiaoqing Wang
- Department of Cardiology, Shenzhen Sun Yat-Sen cardiovascular hospital, Shenzhen 518112, China
| | - Zhanchao Xian
- Department of Cardiology, Shenzhen Sun Yat-Sen cardiovascular hospital, Shenzhen 518112, China
| | - Xin Liu
- Research center for biomedical information technology, Shenzhen institute of advance technology, Chinese academic of science, Shenzhen 518055, China
- * E-mail: (XL); (WH)
| | - Wenhua Huang
- Institutes of Clinical Anatomy, Southern Medical University, Guangzhou 510515, China
- * E-mail: (XL); (WH)
| | - Pengcheng Xu
- Institutes of Clinical Anatomy, Southern Medical University, Guangzhou 510515, China
| | - Jinyang Wang
- Institutes of Clinical Anatomy, Southern Medical University, Guangzhou 510515, China
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Govindaraju K, Viswanathan GN, Badruddin IA, Kamangar S, Salman Ahmed NJ, Al-Rashed AAAA. The influence of artery wall curvature on the anatomical assessment of stenosis severity derived from fractional flow reserve: a computational fluid dynamics study. Comput Methods Biomech Biomed Engin 2016; 19:1541-9. [PMID: 27052093 DOI: 10.1080/10255842.2016.1170119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment.
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Affiliation(s)
- Kalimuthu Govindaraju
- a Centre for Engineering Programs , HELP College of Arts and Technology , Kuala Lumpur , Malaysia
| | - Girish N Viswanathan
- b Cardiology department , Derriford Hospital , Plymouth , UK.,c Institute of Cellular Medicine , Newcastle University , Newcastle upon Tyne , UK
| | - Irfan Anjum Badruddin
- d Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - Sarfaraz Kamangar
- d Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - N J Salman Ahmed
- e Center for Energy Sciences, Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - Abdullah A A A Al-Rashed
- f Department of Automotive and Marine Engineering Technology , College of Technological Studies, The Public Authority for Applied Education and Training , Kuwait city , Kuwait
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NOVAKOVA L, KOLINSKY J, ADAMEC J, KUDLICKA J, MALIK J. Vascular Stenosis Asymmetry Influences Considerably Pressure Gradient and Flow Volume. Physiol Res 2016; 65:63-9. [DOI: 10.33549/physiolres.932944] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Vascular stenosis is often described only by its percentage in both clinical and scientific praxis. Previous studies gave inconclusive results regarding the effect of stenosis eccentricity on its hemodynamic effect. The aim of this experimental study was to investigate and quantify the effect of stenosis severity and eccentricity on the pressure drop. A combination of pressure and flow measurements by Particle Imaging Velocimetry (PIV) method was used. Models of the same stenosis significance but with different levels of eccentricity were studied in vitro by PIV. This study has shown that stenosis asymmetry is associated with more profound pressure drop and flow volume decrease. On the contrary, pressure drop and flow volume decrease were not further significantly influenced by the level of asymmetry. Hemodynamic changes associated with stenosis eccentricity must be taken into account in both clinical and scientific studies.
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Affiliation(s)
- L. NOVAKOVA
- Department of Fluid Mechanics and Thermomechanics, Faculty of Mechanical Engineering, Czech Technical University in Prague, Czech Republic
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15
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Veselý O, Nováková L, Adamec J. Experimental study of effect of stenosis geometry on pressure loss for periodic flow. EPJ WEB OF CONFERENCES 2016. [DOI: 10.1051/epjconf/201611402132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Taelman L, Bols J, Degroote J, Muthurangu V, Panzer J, Vierendeels J, Segers P. Differential impact of local stiffening and narrowing on hemodynamics in repaired aortic coarctation: an FSI study. Med Biol Eng Comput 2015; 54:497-510. [PMID: 26142885 DOI: 10.1007/s11517-015-1336-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 06/15/2015] [Indexed: 12/22/2022]
Abstract
Even after successful treatment of aortic coarctation, a high risk of cardiovascular morbidity and mortality remains. Uncertainty exists on the factors contributing to this increased risk among which are the presence of (1) a residual narrowing leading to an additional resistance and (2) a less distensible zone disturbing the buffer function of the aorta. As the many interfering factors and adaptive physiological mechanisms present in vivo prohibit the study of the isolated impact of these individual factors, a numerical fluid-structure interaction model is developed to predict central hemodynamics in coarctation treatment. The overall impact of a stiffening on the hemodynamics is limited, with a small increase in systolic pressure (up to 8 mmHg) proximal to the stiffening which is amplified with increasing stiffening and length. A residual narrowing, on the other hand, affects the hemodynamics significantly. For a short segment (10 mm), the combination of a stiffening and narrowing (coarctation index 0.5) causes an increase in systolic pressure of 58 mmHg, with 31 mmHg due to narrowing and an additional 27 mmHg due to stiffening. For a longer segment (25 mm), an increase in systolic pressure of 50 mmHg is found, of which only 9 mmHg is due to stiffening.
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Affiliation(s)
- Liesbeth Taelman
- IBiTech-bioMMeda, iMinds Medical IT, Faculty of Engineering and Architecture, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Joris Bols
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Joris Degroote
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Vivek Muthurangu
- Centre for Cardiovascular MR, UCL Institute of Child Health, London Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK
| | - Joseph Panzer
- Paediatric Cardiology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium
| | - Jan Vierendeels
- Department of Flow, Heat and Combustion Mechanics, Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, 9000, Ghent, Belgium
| | - Patrick Segers
- IBiTech-bioMMeda, iMinds Medical IT, Faculty of Engineering and Architecture, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
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17
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Zhang JM, Luo T, Tan SY, Lomarda AM, Wong ASL, Keng FYJ, Allen JC, Huo Y, Su B, Zhao X, Wan M, Kassab GS, Tan RS, Zhong L. Hemodynamic analysis of patient-specific coronary artery tree. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2015; 31:e02708. [PMID: 25630671 DOI: 10.1002/cnm.2708] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 05/28/2023]
Abstract
Local hemodynamic parameters, such as wall shear stress (WSS), oscillatory shear index and relative resident time (RRT), have been linked to coronary plaque initiation and progression. In this study, a left coronary artery tree model was reconstructed from computed tomography angiography images of a patient with multiple stenoses. The geometry of the coronary artery tree model was virtually restored by eliminating the lesions, essentially re-creating the virtually healthy artery anatomy. Using numerical simulations, flow characteristics and hemodynamic parameter distributions in the stenosed and virtually healthy models were investigated. In the virtually healthy artery model, disturbed flows were found at four locations, prone to initialization of plaque formation. Low WSS and high RRT were exhibited in three of the four locations, and high WSS and low RRT were exhibited in the fourth. These findings suggest that coronary plaque is more likely to form in locations with disturbed flow conditions characterized by low WSS and high RRT or high WSS and low RRT. In addition, clinical index of fractional flow reserve was found to significantly correlate with blood flow rate, rather than anatomic parameters, such as diameter stenosis, which implied the importance of hemodynamic environment in stenosis formation.
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Affiliation(s)
- Jun-Mei Zhang
- National Heart Center Singapore, 5 Hospital Drive, 169609, Singapore; Duke-NUS Graduate Medical School, Singapore, 8 College Road, 169857, Singapore
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18
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Saeid Khalafvand S, Han HC. Stability of carotid artery under steady-state and pulsatile blood flow: a fluid-structure interaction study. J Biomech Eng 2015; 137:061007. [PMID: 25761257 DOI: 10.1115/1.4030011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Indexed: 11/08/2022]
Abstract
It has been shown that arteries may buckle into tortuous shapes under lumen pressure, which in turn could alter blood flow. However, the mechanisms of artery instability under pulsatile flow have not been fully understood. The objective of this study was to simulate the buckling and post-buckling behaviors of the carotid artery under pulsatile flow using a fully coupled fluid-structure interaction (FSI) method. The artery wall was modeled as a nonlinear material with a two-fiber strain-energy function. FSI simulations were performed under steady-state flow and pulsatile flow conditions with a prescribed flow velocity profile at the inlet and different pressures at the outlet to determine the critical buckling pressure. Simulations were performed for normal (160 ml/min) and high (350 ml/min) flow rates and normal (1.5) and reduced (1.3) axial stretch ratios to determine the effects of flow rate and axial tension on stability. The results showed that an artery buckled when the lumen pressure exceeded a critical value. The critical mean buckling pressure at pulsatile flow was 17-23% smaller than at steady-state flow. For both steady-state and pulsatile flow, the high flow rate had very little effect (<5%) on the critical buckling pressure. The fluid and wall stresses were drastically altered at the location with maximum deflection. The maximum lumen shear stress occurred at the inner side of the bend and maximum tensile wall stresses occurred at the outer side. These findings improve our understanding of artery instability in vivo.
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Veselý O, Nováková L, Adamec J. Experimental study of effect of stenosis geometry on flow parameters. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/20159202105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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SIDDIQUI AM, HAROON T, BANO Z, ISLAM S. PRESSURE FLOW OF A SECOND GRADE FLUID THROUGH A CHANNEL OF VARYING WIDTH WITH APPLICATION TO STENOSED ARTERY. INT J BIOMATH 2013. [DOI: 10.1142/s1793524513500162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Analytical solutions are obtained for steady flow of an incompressible second grade fluid in an axisymmetric channel of varying width. Three approximate methods are used depending upon three different geometrical configuration. The results obtained are applied to study the flow of a second grade fluid through a smooth constriction. To understand the flow behavior near stenosis, resistance to the flow, shear stress at the wall and stress at the stenosis throat are calculated. The results obtained are numerically evaluated for different values of dimensionless non-Newtonian parameters λ1 and λ2 and maximum height of the stenosis δm. It is observed that as we increase the value of these parameters the resistance to the flow, wall shear stress and stress at the stenosis throat increase.
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Affiliation(s)
- A. M. SIDDIQUI
- Pennsylvania State University, York Campus, Edgecomb PA 1703, USA
| | - T. HAROON
- Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shehzad Islamabad 44000, Pakistan
| | - Z. BANO
- Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shehzad Islamabad 44000, Pakistan
| | - S. ISLAM
- Department Mathematics, Abdul Wali Khan University, Mardan, Pakistan
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WANG XIAOHONG, LI XIAOYANG. THE INFLUENCE OF WALL COMPLIANCE ON FLOW PATTERN IN A CURVED ARTERY EXPOSED TO A DYNAMIC PHYSIOLOGICAL ENVIRONMENT: AN ELASTIC WALL MODEL VERSUS A RIGID WALL MODEL. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519412005095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Plenty of well-established medical research works have shown that many vascular diseases such as stenosis and atherosclerosis are prone to appear in curved arteries. In this paper, we investigated the influence of wall compliance on flow pattern in curved arteries exposed to dynamic physiological environments in order to understand the hemodynamic mechanism and provide a basis for clinical research in related areas. Representative curved arteries with elastic and rigid walls are constructed by computers. The fluid-structure interaction (FSI) effect is considered in our calculations. Physiological velocity profile is assigned as the inlet boundary condition. No-slip boundary condition is applied at the blood-wall interface. Our results show that the maximum axial velocity in the rigid wall model is larger than that in the elastic wall model. Wall compliance also has a remarkable effect on backflow patterns. Significant differences in pressure distribution are found between the elastic and rigid wall models. Blood strain rate distribution patterns in the two models were also compared. It was interesting to discover that in the straight part of the artery, the flexible wall made the counter-rotating vortices induced by the curvature gradually disappear along a downstream direction. However, for the flow feature in the rigid wall model, strong vortices existed throughout the entire straight part of the artery. It revealed that the increment of wall rigidity results in a reduction in wall movement capacity, thus affecting the physiological function of the arterial wall, making it incapable of effectively regulating the flow pattern inside the artery. The current work indicates that the influence of wall compliance on flow pattern in curved artery is significant.
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Affiliation(s)
- XIAOHONG WANG
- Biomechanical Research Laboratory, College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China
| | - XIAOYANG LI
- Biomechanical Research Laboratory, College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang District, Beijing, P. R. China
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Bernad SI, Bernad ES, Craina M, Sargan I, Totoran A, Brisan C. Particle depositions and related hemodynamic parameters in the multiple stenosed right coronary artery. J Clin Med Res 2012; 4:177-89. [PMID: 22719804 PMCID: PMC3376876 DOI: 10.4021/jocmr843w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2012] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Blood flow analysis of the human right coronary artery (RCA) has been carried out to investigate the effects of serial stenosis on coronary hemodynamics. A 3-D model of a serial stenosed RCA was reconstructed based on multislice computerized tomography images. METHODS A velocity waveform in the proximal RCA and a pressure waveform in the distal RCA of a patient with a severe stenosis were acquired with a catheter delivered wire probe and applied as boundary conditions. The numerical analysis examines closely the effect of a multiple serial stenosis on the hemodynamic characteristics such as flow separation, wall shear stress (WSS) and particle depositions. RESULTS AND CONCLUSIONS Energy loss associated with such flow expansion after each constriction will be large and consequently the pressure drop will be higher. Overall pressure drop increased from 1700 Pa (12.75 mmHg) at the end diastole to 11000 Pa (82.5 mmHg) at the peak systole. At the peak systole the WSS values reached 110 Pa in the stenosis with 28% diameter reduction and 210 Pa in the stenosis with 54% diameter reduction, which is high enough to damage the endothelial cells. However at the end of one cardiac cycle a percent of 1.4% (15 from 1063 particles release at the inlet section) remain inside the stenosed RCA.
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Affiliation(s)
- Sandor I. Bernad
- Centre for Fundamental and Advanced Research, Romanian Academy - Timisoara Branch, Timisoara, Romania
| | - Elena S. Bernad
- “Bega” Education and Research Hospital, University of Medicine and Pharmacy “Victor Babes” Timisoara, Romania
| | - Marius Craina
- “Bega” Education and Research Hospital, University of Medicine and Pharmacy “Victor Babes” Timisoara, Romania
| | - Izabella Sargan
- Department of Anatomy, University of Medicine and Pharmacy “Victor Babes” Timisoara, Romania
| | - Alin Totoran
- Department of Biomedical Engineering, Politehnica University of Timisoara, Romania
| | - Cosmin Brisan
- “Bega” Education and Research Hospital, University of Medicine and Pharmacy “Victor Babes” Timisoara, Romania
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23
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Effects of stent-graft geometry and blood hematocrit on hemodynamic in Abdominal Aortic Aneurysm. CHEMICAL AND PROCESS ENGINEERING 2012. [DOI: 10.2478/v10176-012-0005-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Effects of stent-graft geometry and blood hematocrit on hemodynamic in Abdominal Aortic Aneurysm
CFD technique was used to determine the effect of a stent-graft spatial configuration and hematocrit value on blood flow hemodynamic and the risk of a stent-graft occlusion. Spatial configurations of an endovascular prosthesis placed in Abdominal Aortic Aneurysm (AAA) for numerical simulations were developed on the basis of AngioCT data for 10 patients. The results of calculations showed that narrows or angular bends in the prosthesis as well as increased hematocrit affects blood flow reducing velocity and WSS which might result in thrombus development.
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24
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Wang X, Li X. Biomechanical behaviors of curved artery with flexible wall: a numerical study using fluid-structure interaction method. Comput Biol Med 2011; 41:1014-21. [PMID: 21943789 DOI: 10.1016/j.compbiomed.2011.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 08/08/2011] [Accepted: 08/27/2011] [Indexed: 11/26/2022]
Abstract
Studies showed that vascular diseases were prone to occur in curved arteries. In this paper, biomechanical behaviors of curved artery with flexible wall subjected to physiological flow were presented. Fluid-structure interaction effect was considered. The Von Mises stress variation and distribution patterns, the influence of artery curvature and flexibility on peak wall Von Mises stress, diameter change and cross sectional shape variation of the curved artery in the cardiac cycle were studied in detail. We believe that the findings may provide important implications for individualized treatment for patients with cardiovascular disease.
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Affiliation(s)
- Xiaohong Wang
- Biomechanical Research Laboratory, Center of Engineering Mechanics, Beijing University of Technology, No.100 Pingleyuan, Chaoyang District, Beijing, PR China.
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25
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Computational simulation of aortic aneurysm using FSI method: Influence of blood viscosity on aneurismal dynamic behaviors. Comput Biol Med 2011; 41:812-21. [DOI: 10.1016/j.compbiomed.2011.06.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 05/17/2011] [Accepted: 06/28/2011] [Indexed: 11/24/2022]
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26
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Arjmandi-Tash O, Razavi SE, Zanbouri R. Possibility of atherosclerosis in an arterial bifurcation model. BIOIMPACTS : BI 2011; 1:225-8. [PMID: 23678432 DOI: 10.5681/bi.2011.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 11/02/2011] [Accepted: 12/08/2011] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Arterial bifurcations are susceptible locations for formation of atherosclerotic plaques. In the present study, steady blood flow is investigated in a bifurcation model with a non-planar branch. METHODS The influence of different bifurcation angles and non-planar branch is demonstrated on wall shear stress (WSS) distribution using three-dimensional Navier-Stokes equations. RESULTS The WSS values are low in two locations at the top and bottom walls of the mother vessels just before the bifurcation, especially for higher bifurcation angles. These regions approach the apex of bifurcation with decreasing the bifurcation angle. The WSS magnitudes approach near to zero at the outer side of bifurcation plane and these locations are separation-prone. By increasing the bifurcation angle, the minimum WSS decreases at the outer side of bifurcation plane but low WSS region squeezes. WSS peaks exist on the inner side of bifurcation plane near the entry section of daughter vessels and these initial peaks drop as bifurcation angle is increased. CONCLUSION It is concluded that the non-planarity of the daughter vessel lowers the minimum WSS at the outer side of bifurcation and increases the maximum WSS at the inner side. So it seems that the formation of atherosclerotic plaques at bifurcation region in direction of non-planar daughter vessel is more risky.
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Affiliation(s)
- Omid Arjmandi-Tash
- Process Design and Simulation Research Center, School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran
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27
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Keshavarz-Motamed Z, Kadem L. 3D pulsatile flow in a curved tube with coexisting model of aortic stenosis and coarctation of the aorta. Med Eng Phys 2010; 33:315-24. [PMID: 21106429 DOI: 10.1016/j.medengphy.2010.10.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
Abstract
Coarctation of the aorta is a congenital heart disease defined as an obstruction of the aorta distal to the left subclavian artery (between the aortic arch and descending aorta). It is usually associated with other diseases such as bicuspid and tricuspid aortic stenosis. If the coarctation remains uncorrected it can lead to hypertension, left ventricular failure and aortic dissection. Numerous investigations pointed out that there is a relationship between the genesis and the progression of cardiovascular disease and the locally irregular flow occurring at the diseased zone. Therefore, to examine the relationship between arterial disease and hemodynamics conditions, detailed quantitative studies on flow dynamics in arterial models are clearly inquired. In this study we numerically investigate pulsatile blood flow in a simplified model of the aorta (curved pipe) with coexisting coarctation of the aorta and aortic stenosis. Three severities of aortic stenoses (0.61 cm(2), 1.0 cm(2) and 1.5 cm(2)) coexisting with aortic coarctations (50%, 75% and 90% by area) are investigated. An experimentally validated numerical model from literature is used and baseline results are validated against it. To ensure having a physiologically relevant model using this geometry, flow properties are set so that the Dean number falls in the physiological range for the aorta. The results show that the coexistence of these pathologies significantly modifies the flow in a curved pipe. The maximal velocity is shifted towards the outer wall and can reach values as high as 5m/s just downstream of the coarctation. The wall shear stress distribution is significantly modified compared to the normal, unobstructed case. Finally, a clinically significant pressure gradient is induced by the curvature of the tube (up to 36 mmHg). This can lead to an overestimation of the severity of the coarctation using catheterization.
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Affiliation(s)
- Z Keshavarz-Motamed
- Mechanical and Industrial Engineering, Concordia University, Montreal, QC, Canada
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Abstract
SUMMARY It is generally believed that plaque rupture and myocardial oxygen supply-demand imbalance contribute approximately equally to the burden of peri-operative myocardial infarction. This review critically analyses data of post-mortem, pre-operative coronary angiography, troponin surveillance, other pre-operative non-invasive investigations, and peri-operative haemodynamic predictors of myocardial ischaemia and/or myocardial infarction. The current evidence suggests that myocardial oxygen supply-demand imbalance predominates in the early postoperative period. It is likely that flow stagnation and thrombus formation is an important pathway in the development of a peri-operative myocardial infarction, in addition to the more commonly recognised role of peri-operative tachycardia. Research and therapeutic interventions should be focused on the prediction and therapy of flow stagnation and thrombus formation. Plaque rupture appears to be a more random event, distributed over the entire peri-operative admission.
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Affiliation(s)
- B M Biccard
- Department of Anaesthetics, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Inkosi Albert Luthuli Central Hospital, South Africa.
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29
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Niazmand H, Rajabi Jaghargh E. Bend Sweep Angle and Reynolds Number Effects on Hemodynamics of S-Shaped Arteries. Ann Biomed Eng 2010; 38:2817-28. [DOI: 10.1007/s10439-010-0043-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 04/09/2010] [Indexed: 11/30/2022]
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30
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Balocco S, Basset O, Azencot J, Tortoli P, Cachard C. 3D dynamic model of healthy and pathologic arteries for ultrasound technique evaluation. Med Phys 2008; 35:5440-50. [DOI: 10.1118/1.3006948] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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