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Activation and inflammation of the venous endothelium in vein graft disease. Atherosclerosis 2017; 265:266-274. [PMID: 28865843 DOI: 10.1016/j.atherosclerosis.2017.08.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/19/2017] [Accepted: 08/23/2017] [Indexed: 01/13/2023]
Abstract
The long saphenous vein is the most commonly used conduit in coronary artery bypass graft (CABG) surgery when bypassing multiple diseased arteries; however, its use is complicated by the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis leading to compromised graft efficacy. Despite refinement of surgical techniques to improve graft patency, late vein graft failure remains a significant problem. Moreover, there is a lack of pharmacological interventions proven to be effective in the treatment of late vein graft failure. A greater understanding of the molecular nature of the disease and the interactions between endothelial and smooth muscle cells as a result of alterations in local haemodynamics may assist with designing future beneficial pharmacological interventions. Venous endothelial cells (ECs) are physiologically adapted to chronic low shear stress; however, once the graft is implanted into the arterial circulation, they become suddenly exposed to acute high levels of shear stress. A small number of in vitro and ex vivo studies have demonstrated that acute high shear stress is associated with the activation of a pro-inflammatory profile in saphenous vein ECs, which may be mediated by mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signalling pathways. The impact of acute changes in shear stress on venous ECs and the role of ECs in the development of intimal hyperplasia remains incomplete and is the subject of this review.
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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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Ruiz-Soler A, Kabinejadian F, Slevin MA, Bartolo PJ, Keshmiri A. Optimisation of a Novel Spiral-Inducing Bypass Graft Using Computational Fluid Dynamics. Sci Rep 2017; 7:1865. [PMID: 28500311 PMCID: PMC5431846 DOI: 10.1038/s41598-017-01930-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/06/2017] [Indexed: 11/09/2022] Open
Abstract
Graft failure is currently a major concern for medical practitioners in treating Peripheral Vascular Disease (PVD) and Coronary Artery Disease (CAD). It is now widely accepted that unfavourable haemodynamic conditions play an essential role in the formation and development of intimal hyperplasia, which is the main cause of graft failure. This paper uses Computational Fluid Dynamics (CFD) to conduct a parametric study to enhance the design and performance of a novel prosthetic graft, which utilises internal ridge(s) to induce spiral flow. This design is primarily based on the identification of the blood flow as spiral in the whole arterial system and is believed to improve the graft longevity and patency rates at distal graft anastomoses. Four different design parameters were assessed in this work and the trailing edge orientation of the ridge was identified as the most important parameter to induce physiological swirling flow, while the height of the ridge also significantly contributed to the enhanced performance of this type of graft. Building on these conclusions, an enhanced configuration of spiral graft is proposed and compared against conventional and spiral grafts to reaffirm its potential benefits.
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Affiliation(s)
- Andres Ruiz-Soler
- Engineering and Materials Research Centre, Manchester Metropolitan University, Manchester, M1 5GD, UK.,School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Foad Kabinejadian
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109-2110, USA
| | - Mark A Slevin
- Healthcare Science Research Centre, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | - Paulo J Bartolo
- School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Amir Keshmiri
- School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK.
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Impact of Using Conventional Inlet/Outlet Boundary Conditions on Haemodynamic Metrics in a Subject-Specific Rabbit Aorta. Proc Inst Mech Eng H 2017; 232:103-113. [DOI: 10.1177/0954411917699237] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Computational fluid dynamics is a tool capable of accurately measuring metrics currently used to predict the behaviour of cardiovascular diseases. This study quantifies the impact various commonly used inlet and outlet boundary conditions have on various shear rate–based haemodynamic metrics currently used for predicting the localisation of cardiovascular diseases. Simulations are conducted on an accurately represented rabbit aorta configuration and comparison has been made against available in vivo data. The boundary conditions studied include two different inlet profiles, three outlet boundary conditions, and steady-state versus pulsatile flow cases. Large variations were found in the results, particularly when using different outlet boundary conditions, and the discrepancies were evaluated both quantitatively and qualitatively. The results clearly highlight the importance of the type of boundary condition used when simulating complex cardiovascular models. By restricting the attention to the flow within the aorta and the intercostal branches, the results suggest that prescribing transient simulation and fully developed flow at the inlet are not required. Furthermore, assuming the widely accepted low wall shear stress theory of Caro, it was found that Murray’s law–based outlet boundary condition returns the most physiologically accurate results when compared to in vivo data.
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55
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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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Cardioprotective Effects of Exosomes and Their Potential Therapeutic Use. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 998:163-177. [PMID: 28936739 DOI: 10.1007/978-981-10-4397-0_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Exosomes are membrane-contained vesicles released by various types of cells both in animals and human. They contain microRNAs and proteins and can travel to target cells, affecting their functions. There are specific factors on the surface of every exosomes, making sure that they will be taken up by certain type of cells. With these features, exosomes have been recognized to be one of the fundamental "messengers" for cell-cell communication. Recently, increased interest has been raised in exosomes since they were discovered to play an unneglectable role in preserving cardiac function and cardiomyocyte repair during stress. The widely explored stem cell therapy for cardiomyopathy uncovered the contribution of exosomes. Here we summarized cardioprotective effects of exosomes and their potential therapeutic use.
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Numerical Assessment of Novel Helical/Spiral Grafts with Improved Hemodynamics for Distal Graft Anastomoses. PLoS One 2016; 11:e0165892. [PMID: 27861485 PMCID: PMC5115668 DOI: 10.1371/journal.pone.0165892] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 10/19/2016] [Indexed: 11/19/2022] Open
Abstract
In the present work, numerical simulations were conducted for a typical end-to-side distal graft anastomosis to assess the effects of inducing secondary flow, which is believed to remove unfavourable flow environment. Simulations were carried out for four models, generated based on two main features of 'out-of-plane helicity' and 'spiral ridge' in the grafts as well as their combination. Following a qualitative comparison against in vitro data, various mean flow and hemodynamic parameters were compared and the results showed that helicity is significantly more effective in inducing swirling flow in comparison to a spiral ridge, while their combination could be even more effective. In addition, the induced swirling flow was generally found to be increasing the wall shear stress and reducing the flow stagnation and particle residence time within the anastomotic region and the host artery, which may be beneficial to the graft longevity and patency rates. Finally, a parametric study on the spiral ridge geometrical features was conducted, which showed that the ridge height and the number of spiral ridges have significant effects on inducing swirling flow, and revealed the potential of improving the efficiency of such designs.
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Kato T, Tsunekawa T, Motoji Y, Hirakawa A, Okawa Y, Tomita S. The side-to-side fashion for individual distal coronary anastomosis using venous conduit. Heart Vessels 2016; 32:385-389. [PMID: 27631536 DOI: 10.1007/s00380-016-0890-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 09/07/2016] [Indexed: 11/26/2022]
Abstract
Regarding to coronary artery bypass grafting (CABG), the end-to-side anastomosis (ESA) has been performed as a gold standard. Recently, the effectiveness of the distal side-to-side anastomosis (SSA) in CABG using internal mammary artery has been reported. The benefit of SSA comparing to ESA also has been disclosed by computing simulation. However, use of SSA by venous conduit for individual CABG has not been reported. In this study, we investigated feasibility of SSA. From January 2013 to October 2014, we conducted 114 CABGs. There were 92 venous distal anastomoses without sequential anastomotic site (61 SSA and 31 ESA). The anastomosis was evaluated before discharge and at 1 year after the procedure by angiography or multi-detector row computed tomographic coronary angiography. The median values for time to anastomosis were 13 min in the two group (p = 0.89). There was no revision of anastomosis in both groups. Additional stitches for hemostasis were required significantly less in SSA than ESA (18.0 vs 45.2 %, respectively, p < 0.05). Early angiographic patency; 96.6 % for SSA vs 93.5 % for ESA (p = 0.50), and percentage of good anastomotic figure; 91.2 % for SSA vs 87.1 % for ESA (p = 0.54) were similar in both groups. The angiographic patency at 1 year were 92.9 % for SSA and 81.0 % for ESA (p = 0.16). There was no predictive factor for early and late graft failure. Our study showed feasibility of SSA using venous conduit in individual CABG based on early and mid-term angiographic results. This anastomotic fashion is easy to perform and maybe beneficial in blood flow pattern.
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Affiliation(s)
- Takayoshi Kato
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4 Yabuta-minami, Gifu, Gifu, 500-8384, Japan.
| | - Tomohiro Tsunekawa
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4 Yabuta-minami, Gifu, Gifu, 500-8384, Japan
| | - Yusuke Motoji
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4 Yabuta-minami, Gifu, Gifu, 500-8384, Japan
| | - Akihiro Hirakawa
- Biostatistics and Bioinformatics Section, Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Nagoya, Aichi, Japan
| | - Yasuhide Okawa
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4 Yabuta-minami, Gifu, Gifu, 500-8384, Japan
| | - Shinji Tomita
- Department of Cardiovascular Surgery, Gifu Heart Center, 4-14-4 Yabuta-minami, Gifu, Gifu, 500-8384, Japan
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Ha H, Kim GB, Kweon J, Lee SJ, Kim YH, Kim N, Yang DH. The influence of the aortic valve angle on the hemodynamic features of the thoracic aorta. Sci Rep 2016; 6:32316. [PMID: 27561388 PMCID: PMC4999809 DOI: 10.1038/srep32316] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 08/02/2016] [Indexed: 11/17/2022] Open
Abstract
Since the first observation of a helical flow pattern in aortic blood flow, the existence of helical blood flow has been found to be associated with various pathological conditions such as bicuspid aortic valve, aortic stenosis, and aortic dilatation. However, an understanding of the development of helical blood flow and its clinical implications are still lacking. In our present study, we hypothesized that the direction and angle of aortic inflow can influence helical flow patterns and related hemodynamic features in the thoracic aorta. Therefore, we investigated the hemodynamic features in the thoracic aorta and various aortic inflow angles using patient-specific vascular phantoms that were generated using a 3D printer and time-resolved, 3D, phase-contrast magnetic resonance imaging (PC-MRI). The results show that the rotational direction and strength of helical blood flow in the thoracic aorta largely vary according to the inflow direction of the aorta, and a higher helical velocity results in higher wall shear stress distributions. In addition, right-handed rotational flow conditions with higher rotational velocities imply a larger total kinetic energy than left-handed rotational flow conditions with lower rotational velocities.
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Affiliation(s)
- Hojin Ha
- POSTECH Biotech Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea
| | - Guk Bae Kim
- Asan Institute of Life Science, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
| | - Jihoon Kweon
- Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
| | - Sang Joon Lee
- POSTECH Biotech Center, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784, South Korea
| | - Young-Hak Kim
- Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
| | - Namkug Kim
- Department of Convergence Medicine, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
| | - Dong Hyun Yang
- Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
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60
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Tamimi E, Ardila DC, Haskett DG, Doetschman T, Slepian MJ, Kellar RS, Vande Geest JP. Biomechanical Comparison of Glutaraldehyde-Crosslinked Gelatin Fibrinogen Electrospun Scaffolds to Porcine Coronary Arteries. J Biomech Eng 2016; 138:2466198. [PMID: 26501189 DOI: 10.1115/1.4031847] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Indexed: 12/17/2022]
Abstract
Cardiovascular disease (CVD) is the leading cause of death for Americans. As coronary artery bypass graft surgery (CABG) remains a mainstay of therapy for CVD and native vein grafts are limited by issues of supply and lifespan, an effective readily available tissue-engineered vascular graft (TEVG) for use in CABG would provide drastic improvements in patient care. Biomechanical mismatch between vascular grafts and native vasculature has been shown to be the major cause of graft failure, and therefore, there is need for compliance-matched biocompatible TEVGs for clinical implantation. The current study investigates the biaxial mechanical characterization of acellular electrospun glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen cylindrical constructs, using a custom-made microbiaxial optomechanical device (MOD). Constructs crosslinked for 2, 8, and 24 hrs are compared to mechanically characterized porcine left anterior descending coronary (LADC) artery. The mechanical response data were used for constitutive modeling using a modified Fung strain energy equation. The results showed that constructs crosslinked for 2 and 8 hrs exhibited circumferential and axial tangential moduli (ATM) similar to that of the LADC. Furthermore, the 8-hrs experimental group was the only one to compliance-match the LADC, with compliance values of 0.0006±0.00018 mm Hg-1 and 0.00071±0.00027 mm Hg-1, respectively. The results of this study show the feasibility of meeting mechanical specifications expected of native arteries through manipulating GLUT vapor crosslinking time. The comprehensive mechanical characterization of cylindrical biopolymer constructs in this study is an important first step to successfully develop a biopolymer compliance-matched TEVG.
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61
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Wu Y, Liu G, Chen W, Yang M, Zhu C. 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside reduces intimal hyperplasia of tissue engineering blood vessel by inhibiting phenotype switch of vascular smooth muscle cell. J Biomed Mater Res B Appl Biomater 2016; 105:744-752. [PMID: 26743435 DOI: 10.1002/jbm.b.33585] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 09/11/2015] [Accepted: 11/18/2015] [Indexed: 12/12/2022]
Abstract
Intimal hyperplasia (IH) is the cause of clinical failure in patients with vascular transplants and intravascular stents. The proliferation and phenotype switching of vascular smooth muscle cells (VSMCs) play important roles in IH. Inhibiting the proliferation of VSMCs and maintaining the differentiated phenotype of VSMCs is one way to reduce IH. In this article, 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) was used in experiments after drug screening. We found that the metabolism, autophagy, and differentiation of VSMCs were enhanced which were important to the normal function of VSMCs, but the secretion of VSMCs was reduced after AICAR treatment. AICAR induces G1 phase arrest and inhibits the proliferation of VSMCs using the MTT and EdU assays and cell cycle analysis. Then, the rat carotid artery vessel transplantation model was used to evaluate the function of AICAR in vivo. AICAR-modified tissue-engineered blood vessels (TEBVs) had a higher patency rate and less IH than the control TEBVs. In conclusion, AICAR can improve the normal function of VSMCs by increasing the metabolism and autophagy of VSMCs but inhibit the proliferation, paracrine, and phenotypes switching of VSMCs, further contribute the reducing of IH in TEBVs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 744-752, 2017.
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Affiliation(s)
- Yangxiao Wu
- Department of Anatomy, Key Lab for Biomechanics and Tissue Engineering of Chongqing, Third Military Medical University, Chongqing, 400038, China
| | - Ge Liu
- Department of Anatomy, Key Lab for Biomechanics and Tissue Engineering of Chongqing, Third Military Medical University, Chongqing, 400038, China
| | - Wen Chen
- Department of Anatomy, Key Lab for Biomechanics and Tissue Engineering of Chongqing, Third Military Medical University, Chongqing, 400038, China
| | - Mingcan Yang
- Department of Anatomy, Key Lab for Biomechanics and Tissue Engineering of Chongqing, Third Military Medical University, Chongqing, 400038, China
| | - Chuhong Zhu
- Department of Anatomy, Key Lab for Biomechanics and Tissue Engineering of Chongqing, Third Military Medical University, Chongqing, 400038, China
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Ostdiek AM, Ivey JR, Grant DA, Gopaldas J, Grant SA. An in vivo study of a gold nanocomposite biomaterial for vascular repair. Biomaterials 2015; 65:175-83. [PMID: 26164402 PMCID: PMC4507082 DOI: 10.1016/j.biomaterials.2015.06.045] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 06/26/2015] [Indexed: 01/05/2023]
Abstract
Currently vascular repairs are treated using synthetic or biologic patches, however these patches have an array of complications, including calcification, rupture, re-stenosis, and intimal hyperplasia. An active patch material composed of decellularized tissue conjugated to gold nanoparticles (AuNPs) was developed and the long term biocompatibility and cellular integration was investigated. Porcine abdominal aortic tissue was decellularized and conjugated with 100 nm gold nanoparticles (AuNP). These patches were placed over a longitudinal arteriotomy of the thoracic aorta in six pigs. The animals were monitored for six months. Gross, histological, and immunohistochemical analyses of the patches were performed after euthanasia. Grossly there was minimal scar tissue with the patches still visible on the outer surface of the vessel. The inner lumen was smooth with a seamless transition from patch to native tissue. Histology demonstrated infiltration of host cells into the patch material. The immunohistochemical results demonstrated an endothelial cell layer forming over the patch within the vessel. Smooth muscle cells were repopulating the biomaterial in all animals. These results demonstrated that the AuNP biomaterial patch integrated well with the host tissue and did not failed over the six month implantation time.
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Affiliation(s)
- A M Ostdiek
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA.
| | - J R Ivey
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA.
| | - D A Grant
- Department of Bioengineering, University of Missouri, Columbia, MO 65211, USA.
| | - J Gopaldas
- Prairie Cardiovascular, Springfield, IL 62701, USA.
| | - S A Grant
- Department of Bioengineering, University of Missouri, Columbia, MO 65211, USA.
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63
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Ha H, Choi W, Park H, Lee SJ. Effect of swirling blood flow on vortex formation at post-stenosis. Proc Inst Mech Eng H 2015; 229:175-83. [PMID: 25767153 DOI: 10.1177/0954411915573065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Various clinical observations reported that swirling blood flow is a normal physiological flow pattern in various vasculatures. The swirling flow has beneficial effects on blood circulation through the blood vessels. It enhances oxygen transfer and reduces low-density lipoprotein concentration in the blood vessel by enhancing cross-plane mixing of the blood. However, the fluid-dynamic roles of the swirling flow are not yet fully understood. In this study, inhibition of material deposition at the post-stenosis region by the swirling flow was observed. To reveal the underlying fluid-dynamic characteristics, pathline flow visualization and time-resolved particle image velocimetry measurements were conducted. Results showed that the swirling inlet flow increased the development of vortices at near wall region of the post-stenosis, which can suppress further development of stenosis by enhancing transport and mixing of the blood flow. The fluid-dynamic characteristics obtained in this study would be useful for improving hemodynamic characteristics of vascular grafts and stents in which the stenosis frequently occurred. Moreover, the time-resolved particle image velocimetry measurement technique and vortex identification method employed in this study would be useful for investigating the fluid-dynamic effects of the swirling flow on various vascular environments.
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Affiliation(s)
- Hojin Ha
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Woorak Choi
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Hanwook Park
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Sang Joon Lee
- Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Republic of Korea
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Ha H, Choi W, Lee SJ. Beneficial fluid-dynamic features of pulsatile swirling flow in 45° end-to-side anastomosis. Med Eng Phys 2015; 37:272-9. [DOI: 10.1016/j.medengphy.2015.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Revised: 11/29/2014] [Accepted: 01/11/2015] [Indexed: 11/17/2022]
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65
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Effects of a carotid covered stent with a novel membrane design on the blood flow regime and hemodynamic parameters distribution at the carotid artery bifurcation. Med Biol Eng Comput 2014; 53:165-77. [DOI: 10.1007/s11517-014-1222-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/21/2014] [Indexed: 10/24/2022]
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66
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Ha H, Hwang D, Choi WR, Baek J, Lee SJ. Fluid-dynamic optimal design of helical vascular graft for stenotic disturbed flow. PLoS One 2014; 9:e111047. [PMID: 25360705 PMCID: PMC4215892 DOI: 10.1371/journal.pone.0111047] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 09/22/2014] [Indexed: 11/18/2022] Open
Abstract
Although a helical configuration of a prosthetic vascular graft appears to be clinically beneficial in suppressing thrombosis and intimal hyperplasia, an optimization of a helical design has yet to be achieved because of the lack of a detailed understanding on hemodynamic features in helical grafts and their fluid dynamic influences. In the present study, the swirling flow in a helical graft was hypothesized to have beneficial influences on a disturbed flow structure such as stenotic flow. The characteristics of swirling flows generated by helical tubes with various helical pitches and curvatures were investigated to prove the hypothesis. The fluid dynamic influences of these helical tubes on stenotic flow were quantitatively analysed by using a particle image velocimetry technique. Results showed that the swirling intensity and helicity of the swirling flow have a linear relation with a modified Germano number (Gn*) of the helical pipe. In addition, the swirling flow generated a beneficial flow structure at the stenosis by reducing the size of the recirculation flow under steady and pulsatile flow conditions. Therefore, the beneficial effects of a helical graft on the flow field can be estimated by using the magnitude of Gn*. Finally, an optimized helical design with a maximum Gn* was suggested for the future design of a vascular graft.
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Affiliation(s)
- Hojin Ha
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
| | - Dongha Hwang
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
| | - Woo-Rak Choi
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
| | - Jehyun Baek
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
| | - Sang Joon Lee
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
- Center for Biofluid and Biomimic Research, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, Republic of Korea
- * E-mail:
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Kabinejadian F, Ghista DN, Su B, Kaabi Nezhadian M, Chua LP, Yeo JH, Leo HL. In vitro measurements of velocity and wall shear stress in a novel sequential anastomotic graft design model under pulsatile flow conditions. Med Eng Phys 2014; 36:1233-45. [DOI: 10.1016/j.medengphy.2014.06.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 06/19/2014] [Accepted: 06/28/2014] [Indexed: 10/24/2022]
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Li H, Xie B, Gu C, Gao M, Zhang F, Wang J, Dai L, Yu Y. Distal end side-to-side anastomoses of sequential vein graft to small target coronary arteries improve intraoperative graft flow. BMC Cardiovasc Disord 2014; 14:65. [PMID: 24884776 PMCID: PMC4023697 DOI: 10.1186/1471-2261-14-65] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 04/29/2014] [Indexed: 11/24/2022] Open
Abstract
Background End-to-side anastomoses to connect the distal end of the great saphenous vein (GSV) to small target coronary arteries are commonly performed in sequential coronary artery bypass grafting (CABG). However, the oversize diameter ratio between the GSV and small target vessels at end-to-side anastomoses might induce adverse hemodynamic condition. The purpose of this study was to describe a distal end side-to-side anastomosis technique and retrospectively compare the effect of distal end side-to-side versus end-to-side anastomosis on graft flow characteristics. Methods We performed side-to-side anastomoses to connect the distal end of the GSV to small target vessels on 30 patients undergoing off-pump sequential CABG in our hospital between October 2012 and July 2013. Among the 30 patients, end-to-side anastomoses at the distal end of the GSV were initially performed on 14 patients; however, due to poor graft flow, those anastomoses were revised into side-to-side anastomoses. We retrospectively compared the intraoperative graft flow characteristics of the end-to-side versus side-to-side anastomoses in the 14 patients. The patient outcomes were also evaluated. Results We found that the side-to-side anastomosis reconstruction improved intraoperative flow and reduced pulsatility index in all the 14 patients significantly. The 16 patients who had the distal end side-to-side anastomoses performed directly also exhibited satisfactory intraoperative graft flow. Three-month postoperative outcomes for all the patients were satisfactory. Conclusions Side-to-side anastomosis at the distal end of sequential vein grafts might be a promising strategy to connect small target coronary arteries to the GSV.
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Affiliation(s)
| | | | | | | | | | | | | | - Yang Yu
- Department of Cardiac Surgery, Beijing An Zhen Hospital, Capital Medical University, Beijing 100029, China.
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