1
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Mii S, Guntani A, Yamashita S, Ishida M. Importance of Flow Waveform and Flow Volume as Prognostic Indicators for the Patency of Infra-Inguinal Autologous Vein Bypass. Eur J Vasc Endovasc Surg 2023; 65:546-554. [PMID: 36592653 DOI: 10.1016/j.ejvs.2022.12.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 11/14/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To investigate the association of the intra-operative flow waveform and the flow volume with graft prognosis of the infra-inguinal vein bypass. METHODS This was a retrospective study of intra-operative flowmetry performed for infra-inguinal autologous vein bypass between 2011 and 2020. Flow waveforms were classified as type 0 - IV according to the Kyushu University (KU) classification. The patients (n = 340) were divided into three groups based on the flow waveform predicting the graft patency: type 0/I (long patency), type II (no early occlusion but late occlusion possible), and type III/IV (early occlusion). The graft occlusion rates of popliteal artery bypass (PAB) and infrapopliteal artery bypass (IPAB) within 30 days of surgery were compared between type 0/I + II and type III/IV groups, while the midterm graft patency rates were compared between type 0/I and type II groups. Additionally, a multivariate analysis was performed to identify independent risk factors for early and late graft occlusion. RESULTS The early graft occlusion rates of type 0/I + II and type III/IV groups were 3.9% and 0%, respectively, (p = 1.0) for PAB, and 5.3% and 46.2%, respectively, (p < .001) for IPAB. The two year primary patency rates of type 0/I and type II groups were 91% and 75%, respectively, (p = .030) for PAB, and 58% and 63%, respectively, (p = .72) for IPAB. Independent risk factors for early occlusion were none in PAB and flow waveform (type IV) in IPAB. Independent risk factors for patency loss in PAB were flow waveform (type II), end stage renal disease, and dual antiplatelet use, and those in IPAB were older age, women, lower flow volume, and iterative bypass. CONCLUSION Intra-operative flowmetry is useful for predicting the graft prognosis in infra-inguinal vein bypass and this is dependent on the distal target artery.
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Affiliation(s)
- Shinsuke Mii
- Department of Vascular Surgery, Saiseikai Yahata General Hospital, Kitakyushu, Japan.
| | - Atsushi Guntani
- Department of Vascular Surgery, Saiseikai Yahata General Hospital, Kitakyushu, Japan
| | - Sho Yamashita
- Department of Vascular Surgery, Saiseikai Yahata General Hospital, Kitakyushu, Japan
| | - Masaru Ishida
- Department of Vascular Surgery, Steel Memorial Yawata Hospital, Kitakyushu, Japan
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2
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Corti A, Colombo M, Migliavacca F, Rodriguez Matas JF, Casarin S, Chiastra C. Multiscale Computational Modeling of Vascular Adaptation: A Systems Biology Approach Using Agent-Based Models. Front Bioeng Biotechnol 2021; 9:744560. [PMID: 34796166 PMCID: PMC8593007 DOI: 10.3389/fbioe.2021.744560] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/04/2021] [Indexed: 12/20/2022] Open
Abstract
The widespread incidence of cardiovascular diseases and associated mortality and morbidity, along with the advent of powerful computational resources, have fostered an extensive research in computational modeling of vascular pathophysiology field and promoted in-silico models as a support for biomedical research. Given the multiscale nature of biological systems, the integration of phenomena at different spatial and temporal scales has emerged to be essential in capturing mechanobiological mechanisms underlying vascular adaptation processes. In this regard, agent-based models have demonstrated to successfully embed the systems biology principles and capture the emergent behavior of cellular systems under different pathophysiological conditions. Furthermore, through their modular structure, agent-based models are suitable to be integrated with continuum-based models within a multiscale framework that can link the molecular pathways to the cell and tissue levels. This can allow improving existing therapies and/or developing new therapeutic strategies. The present review examines the multiscale computational frameworks of vascular adaptation with an emphasis on the integration of agent-based approaches with continuum models to describe vascular pathophysiology in a systems biology perspective. The state-of-the-art highlights the current gaps and limitations in the field, thus shedding light on new areas to be explored that may become the future research focus. The inclusion of molecular intracellular pathways (e.g., genomics or proteomics) within the multiscale agent-based modeling frameworks will certainly provide a great contribution to the promising personalized medicine. Efforts will be also needed to address the challenges encountered for the verification, uncertainty quantification, calibration and validation of these multiscale frameworks.
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Affiliation(s)
- Anna Corti
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Monika Colombo
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.,Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Switzerland
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Jose Felix Rodriguez Matas
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Stefano Casarin
- Department of Surgery, Houston Methodist Hospital, Houston, TX, United States.,Center for Computational Surgery, Houston Methodist Research Institute, Houston, TX, United States.,Houston Methodist Academic Institute, Houston, TX, United States
| | - Claudio Chiastra
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.,PoliToMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
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3
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Abstract
Maternal cardiovascular changes during pregnancy include an expansion of plasma volume, increased cardiac output, decreased peripheral resistance, and increased uteroplacental blood flow. These adaptations facilitate the progressive increase in uteroplacental perfusion that is required for normal fetal growth and development, prevent the development of hypertension, and provide a reserve of blood in anticipation of the significant blood loss associated with parturition. Each woman's genotype and phenotype determine her ability to adapt in response to molecular signals that emanate from the fetoplacental unit. Here, we provide an overview of the major hemodynamic and cardiac changes and then consider regional changes in the splanchnic, renal, cerebral, and uterine circulations in terms of endothelial and vascular smooth muscle cell plasticity. Although consideration of gestational disease is beyond the scope of this review, aberrant signaling and/or maternal responsiveness contribute to the etiology of several common gestational diseases such as preeclampsia, intrauterine growth restriction, and gestational diabetes.
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Affiliation(s)
- George Osol
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405, USA;
| | - Nga Ling Ko
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405, USA;
| | - Maurizio Mandalà
- Department of Biology, Ecology and Earth Science, University of Calabria, 87036 Arcavacata di Rende (CS), Italy
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4
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Ko NL, Mandalà M, John L, Gelinne A, Osol G. Venoarterial communication mediates arterial wall shear stress-induced maternal uterine vascular remodeling during pregnancy. Am J Physiol Heart Circ Physiol 2018; 315:H709-H717. [PMID: 29775414 DOI: 10.1152/ajpheart.00126.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although expansive remodeling of the maternal uterine circulation during pregnancy is essential for maintaining uteroplacental perfusion and normal fetal growth, the underlying physiological mechanisms are not well understood. Using a rat model, surgical approaches were used to alter uterine hemodynamics and wall shear stress (WSS) to evaluate the effects of WSS and venoarterial communication (e.g., transfer of placentally derived growth signals from postplacental veins to preplacental arteries) on gestational uterine vascular remodeling. Changes in WSS secondary to ligation of the cervical but not the ovarian end of the main uterine artery and vein provoked significant expansive remodeling at the opposite end of both vessels, but only in pregnant animals. The ≈50% increase in lumen diameter (relative to the contralateral horn) was associated with an upregulation of total endothelial nitric oxide (NO) synthase expression and was abolished by in vivo NO synthase inhibition with N-nitro-l-arginine methyl ester. Complete removal of a venous segment adjacent to the uterine artery to eliminate local venous influences significantly attenuated the WSS-induced remodeling by about one-half ( P < 0.05). These findings indicate that, during pregnancy, 1) increased WSS stimulates uterine artery growth via NO signaling and 2) the presence of an adjacent vein is required for arterial remodeling to fully occur. NEW & NOTEWORTHY This study provides the first in vivo evidence for the importance of venous influences on arterial growth within the uteroplacental circulation.
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Affiliation(s)
- Nga Ling Ko
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont , Burlington, Vermont
| | - Maurizio Mandalà
- Department of Biology, Ecology, and Earth Science, University of Calabria , Cosenza , Italy
| | - Liam John
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont , Burlington, Vermont
| | - Aaron Gelinne
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont , Burlington, Vermont
| | - George Osol
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Larner College of Medicine, University of Vermont , Burlington, Vermont
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5
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Biomechanical property and modelling of venous wall. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 133:56-75. [DOI: 10.1016/j.pbiomolbio.2017.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 11/18/2022]
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6
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Donadoni F, Pichardo-Almarza C, Bartlett M, Dardik A, Homer-Vanniasinkam S, Díaz-Zuccarini V. Patient-Specific, Multi-Scale Modeling of Neointimal Hyperplasia in Vein Grafts. Front Physiol 2017; 8:226. [PMID: 28458640 PMCID: PMC5394124 DOI: 10.3389/fphys.2017.00226] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/30/2017] [Indexed: 11/16/2022] Open
Abstract
Neointimal hyperplasia is amongst the major causes of failure of bypass grafts. The disease progression varies from patient to patient due to a range of different factors. In this paper, a mathematical model will be used to understand neointimal hyperplasia in individual patients, combining information from biological experiments and patient-specific data to analyze some aspects of the disease, particularly with regard to mechanical stimuli due to shear stresses on the vessel wall. By combining a biochemical model of cell growth and a patient-specific computational fluid dynamics analysis of blood flow in the lumen, remodeling of the blood vessel is studied by means of a novel computational framework. The framework was used to analyze two vein graft bypasses from one patient: a femoro-popliteal and a femoro-distal bypass. The remodeling of the vessel wall and analysis of the flow for each case was then compared to clinical data and discussed as a potential tool for a better understanding of the disease. Simulation results from this first computational approach showed an overall agreement on the locations of hyperplasia in these patients and demonstrated the potential of using new integrative modeling tools to understand disease progression.
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Affiliation(s)
| | | | | | - Alan Dardik
- The Department of Surgery, Yale University School of MedicineNew Haven, CT, USA.,Veteran Affairs Connecticut Healthcare SystemWest Haven, CT, USA
| | - Shervanthi Homer-Vanniasinkam
- Mechanical Engineering, University College LondonLondon, UK.,Leeds Vascular Institute, Leeds General InfirmaryLeeds, UK.,Division of Surgery, University of WarwickWarwick, UK
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7
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Klein B, Destephens A, Dumeny L, Hu Q, He Y, O'Malley K, Jiang Z, Tran-Son-Tay R, Berceli S. Hemodynamic Influence on Smooth Muscle Cell Kinetics and Phenotype During Early Vein Graft Adaptation. Ann Biomed Eng 2016; 45:644-655. [PMID: 27624660 DOI: 10.1007/s10439-016-1725-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/02/2016] [Indexed: 10/21/2022]
Abstract
Pathologic vascular adaptation following local injury is the primary driver for accelerated intimal hyperplasia and an occlusive phenotype. Smooth muscle cell (SMC) proliferation within the wall, and migration into the developing intima, is a major component of this remodeling response. The primary objective in the current study was to investigate the effect of the local biomechanical forces on early vein graft adaptation, specifically focusing on the spatial and temporal response of SMC proliferation and conversion from a contractile to synthetic architecture. Taking advantage of the differential adaptation that occurs during exposure to divergent flow environments, vein grafts were implanted in rabbits to create two distinct flow environments and harvested at times ranging from 2 h to 28 days. Using an algorithm for the virtual reconstruction of unfixed, histologic specimens, immunohistochemical tracking of DNA synthesis, and high-throughput transcriptional analysis, the spatial and temporal changes in graft morphology, cell proliferation, and SMC phenotype were catalogued. Notable findings include a burst of cell proliferation at 7 days post-implantation, which was significantly augmented by exposure to a reduced flow environment. Compared to the adjacent media, proliferation rates were 3-fold greater in the intima, and a specific spatial distribution of these proliferating cells was identified, with a major peak in the sub-endothelial region and a second peak centering on the internal elastic lamina. Genomic markers of a contractile SMC phenotype were reduced as early as 2 h post-implantation and reached a nadir at 7 days. Network analysis of upstream regulatory pathways identified GATA6 and KLF5 as important transcription factors that regulate this shift in SMC phenotype.
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Affiliation(s)
- Benjamin Klein
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Anthony Destephens
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Leanne Dumeny
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Qiongyao Hu
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Yong He
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Kerri O'Malley
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Zhihua Jiang
- Malcom Randall VA Medical Center, Gainesville, FL, USA.,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA
| | - Roger Tran-Son-Tay
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA.,Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Scott Berceli
- Malcom Randall VA Medical Center, Gainesville, FL, USA. .,Department of Surgery, University of Florida, Box 100128, Gainesville, FL, 32610-0128, USA. .,Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.
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8
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BERNAD ELENAS, BERNAD SANDORI, SARGAN IZABELLA, CRAINA MARIUSL. SAPHENOUS VEIN GRAFT PATENCY AFTER GEOMETRY REMODELING. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415400515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Tortuous saphenous vein graft (SVG) hemodynamics was investigated using computational fluid dynamics (CFD) techniques. Computed tomography (CT) technology is used for noninvasive bypass graft assessment seven days after surgery. CT investigation shows two regions with severe shape remodeling, one is an angle type contortion and the other one is a sharp curvature with tortuous area reduction. The numerical analysis carefully examines the effect of an SVG geometry remodeling through flow separation, particle deposition, and wall shear stress (WSS). During the cardiac cycle, overall pressure drop increases from 2.6[Formula: see text]mmHg to 4.4[Formula: see text]mmHg. In the accelerating part of the systolic phase, particles released in the inlet section move downstream toward the first narrowed part (elbow type contortion) with a helical motion. WSS range along the cardiac cycle varies from 2[Formula: see text]Pa to 42[Formula: see text]Pa, enough to damage the endothelial cells. Vessel torsion induced helical flow can reduce the flow disturbance and separation. Additionally, in the distal end of the graft, the high particle concentrations can promote the inflammatory processes in the vessels.
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Affiliation(s)
- ELENA S. BERNAD
- University of Medicine and Pharmacy “Victor Babes” Timisoara University Clinic “Bega” P-ta Eftimie Murgu 2, RO-300041, Timisoara, Romania
| | - SANDOR I. BERNAD
- Romanian Academy, Timisoara Branch Centre for Fundamental and Advanced Technical Research Bd. Mihai Viteazul 24, RO-300223, Timisoara, Romania
| | - IZABELLA SARGAN
- University of Medicine and Pharmacy “Victor Babes” Timisoara University Clinic “Bega” P-ta Eftimie Murgu 2, RO-300041, Timisoara, Romania
| | - MARIUS L. CRAINA
- University of Medicine and Pharmacy “Victor Babes” Timisoara University Clinic “Bega” P-ta Eftimie Murgu 2, RO-300041, Timisoara, Romania
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9
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Prim DA, Zhou B, Hartstone-Rose A, Uline MJ, Shazly T, Eberth JF. A mechanical argument for the differential performance of coronary artery grafts. J Mech Behav Biomed Mater 2015; 54:93-105. [PMID: 26437296 DOI: 10.1016/j.jmbbm.2015.09.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 09/03/2015] [Accepted: 09/14/2015] [Indexed: 12/17/2022]
Abstract
Coronary artery bypass grafting (CABG) acutely disturbs the homeostatic state of the transplanted vessel making retention of graft patency dependent on chronic remodeling processes. The time course and extent to which remodeling restores vessel homeostasis will depend, in part, on the nature and magnitude of the mechanical disturbances induced upon transplantation. In this investigation, biaxial mechanical testing and histology were performed on the porcine left anterior descending artery (LAD) and analogs of common autografts, including the internal thoracic artery (ITA), radial artery (RA), great saphenous vein (GSV) and lateral saphenous vein (LSV). Experimental data were used to quantify the parameters of a structure-based constitutive model enabling prediction of the acute vessel mechanical response pre-transplantation and under coronary loading conditions. A novel metric Ξ was developed to quantify mechanical differences between each graft vessel in situ and the LAD in situ, while a second metric Ω compares the graft vessels in situ to their state under coronary loading. The relative values of these metrics among candidate autograft sources are consistent with vessel-specific variations in CABG clinical success rates with the ITA as the superior and GSV the inferior graft choices based on mechanical performance. This approach can be used to evaluate other candidate tissues for grafting or to aid in the development of synthetic and tissue engineered alternatives.
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Affiliation(s)
- David A Prim
- University of South Carolina, Biomedical Engineering Program, Columbia, SC, USA
| | - Boran Zhou
- University of South Carolina, Biomedical Engineering Program, Columbia, SC, USA
| | - Adam Hartstone-Rose
- University of South Carolina School of Medicine, Department of Cell Biology and Anatomy, Columbia, SC, USA; University of South Carolina, Department of Anthropology, Columbia, SC, USA
| | - Mark J Uline
- University of South Carolina, Biomedical Engineering Program, Columbia, SC, USA; University of South Carolina, Department of Chemical Engineering, Columbia, SC, USA
| | - Tarek Shazly
- University of South Carolina, Biomedical Engineering Program, Columbia, SC, USA; University of South Carolina, Department of Mechanical Engineering, Columbia, SC, USA
| | - John F Eberth
- University of South Carolina, Biomedical Engineering Program, Columbia, SC, USA; University of South Carolina School of Medicine, Department of Cell Biology and Anatomy, Columbia, SC, USA.
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10
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Veselý J, Horný L, Chlup H, Adámek T, Krajíček M, Žitný R. Constitutive modeling of human saphenous veins at overloading pressures. J Mech Behav Biomed Mater 2015; 45:101-8. [DOI: 10.1016/j.jmbbm.2015.01.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 01/21/2015] [Accepted: 01/29/2015] [Indexed: 12/25/2022]
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11
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Ramachandra AB, Sankaran S, Humphrey JD, Marsden AL. Computational simulation of the adaptive capacity of vein grafts in response to increased pressure. J Biomech Eng 2015; 137:1934919. [PMID: 25376151 PMCID: PMC4321118 DOI: 10.1115/1.4029021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 10/17/2014] [Indexed: 12/12/2022]
Abstract
Vein maladaptation, leading to poor long-term patency, is a serious clinical problem in patients receiving coronary artery bypass grafts (CABGs) or undergoing related clinical procedures that subject veins to elevated blood flow and pressure. We propose a computational model of venous adaptation to altered pressure based on a constrained mixture theory of growth and remodeling (G&R). We identify constitutive parameters that optimally match biaxial data from a mouse vena cava, then numerically subject the vein to altered pressure conditions and quantify the extent of adaptation for a biologically reasonable set of bounds for G&R parameters. We identify conditions under which a vein graft can adapt optimally and explore physiological constraints that lead to maladaptation. Finally, we test the hypothesis that a gradual, rather than a step, change in pressure will reduce maladaptation. Optimization is used to accelerate parameter identification and numerically evaluate hypotheses of vein remodeling.
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Affiliation(s)
- Abhay B. Ramachandra
- Department of Mechanical andAerospace Engineering,University of California San Diego,9500 Gilman Drive,La Jolla, CA 92093
| | - Sethuraman Sankaran
- Senior Computational Scientist HeartFlow, Inc.,1400 Seaport Blvd., Building B,Redwood City, CA 94063
| | - Jay D. Humphrey
- Department of Biomedical Engineering,Yale University,55 Prospect Street,New Haven, CT 06520
| | - Alison L. Marsden
- Department of Mechanicaland Aerospace Engineering,University of California San Diego,9500 Gilman Drive,La Jolla, CA 92093e-mail:
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12
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Vimmr J, Jonášová A, Bublík O. Numerical analysis of non-Newtonian blood flow and wall shear stress in realistic single, double and triple aorto-coronary bypasses. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:1057-1081. [PMID: 23733715 DOI: 10.1002/cnm.2560] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 06/02/2023]
Abstract
Considering the fact that hemodynamics plays an important role in the patency and overall performance of implanted bypass grafts, this work presents a numerical investigation of pulsatile non-Newtonian blood flow in three different patient-specific aorto-coronary bypasses. The three bypass models are distinguished from each other by the number of distal side-to-side and end-to-side anastomoses and denoted as single, double and triple bypasses. The mathematical model in the form of time-dependent nonlinear system of incompressible Navier-Stokes equations is coupled with the Carreau-Yasuda model describing the shear-thinning property of human blood and numerically solved using the principle of the SIMPLE algorithm and cell-centred finite volume method formulated for hybrid unstructured tetrahedral grids. The numerical results computed for non-Newtonian and Newtonian blood flow in the three aorto-coronary bypasses are compared and analysed with emphasis placed on the distribution of cycle-averaged wall shear stress and oscillatory shear index. As shown in this study, the non-Newtonian blood flow in all of the considered bypass models does not significantly differ from the Newtonian one. Our observations further suggest that, especially in the case of sequential grafts, the resulting flow field and shear stimulation are strongly influenced by the diameter of the vessels involved in the bypassing.
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Affiliation(s)
- J Vimmr
- European Centre of Excellence NTIS - New Technologies for Information Society, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic
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13
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Garbey M, Berceli SA. A dynamical system that describes vein graft adaptation and failure. J Theor Biol 2013; 336:209-20. [PMID: 23871714 DOI: 10.1016/j.jtbi.2013.07.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 05/30/2013] [Accepted: 07/09/2013] [Indexed: 11/30/2022]
Abstract
Adaptation of vein bypass grafts to the mechanical stresses imposed by the arterial circulation is thought to be the primary determinant for lesion development, yet an understanding of how the various forces dictate local wall remodeling is lacking. We develop a dynamical system that summarizes the complex interplay between the mechanical environment and cell/matrix kinetics, ultimately dictating changes in the vein graft architecture. Based on a systematic mapping of the parameter space, three general remodeling response patterns are observed: (1) shear stabilized intimal thickening, (2) tension induced wall thinning and lumen expansion, and (3) tension stabilized wall thickening. Notable is our observation that the integration of multiple feedback mechanisms leads to a variety of non-linear responses that would be unanticipated by an analysis of each system component independently. This dynamic analysis supports the clinical observation that the majority of vein grafts proceed along an adaptive trajectory, where grafts dilate and mildly thicken in response to the increased tension and shear, but a small portion of the grafts demonstrate a maladaptive phenotype, where progressive inward remodeling and accentuated wall thickening lead to graft failure.
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Affiliation(s)
- Marc Garbey
- Department of Computer Science, University of Houston, 501 Philip G. Hoffman Hall, Houston, TX 77204-3010, USA; Department of Surgery at The Methodist Hospital, Houston TX, USA; LaSIE, University of La Rochelle, France.
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14
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Hwang M, Garbey M, Berceli SA, Wu R, Jiang Z, Tran-Son-Tay R. Rule-based model of vein graft remodeling. PLoS One 2013; 8:e57822. [PMID: 23533576 PMCID: PMC3606352 DOI: 10.1371/journal.pone.0057822] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 01/26/2013] [Indexed: 11/18/2022] Open
Abstract
When vein segments are implanted into the arterial system for use in arterial bypass grafting, adaptation to the higher pressure and flow of the arterial system is accomplished thorough wall thickening and expansion. These early remodeling events have been found to be closely coupled to the local hemodynamic forces, such as shear stress and wall tension, and are believed to be the foundation for later vein graft failure. To further our mechanistic understanding of the cellular and extracellular interactions that lead to global changes in tissue architecture, a rule-based modeling method is developed through the application of basic rules of behaviors for these molecular and cellular activities. In the current method, smooth muscle cell (SMC), extracellular matrix (ECM), and monocytes are selected as the three components that occupy the elements of a grid system that comprise the developing vein graft intima. The probabilities of the cellular behaviors are developed based on data extracted from in vivo experiments. At each time step, the various probabilities are computed and applied to the SMC and ECM elements to determine their next physical state and behavior. One- and two-dimensional models are developed to test and validate the computational approach. The importance of monocyte infiltration, and the associated effect in augmenting extracellular matrix deposition, was evaluated and found to be an important component in model development. Final model validation is performed using an independent set of experiments, where model predictions of intimal growth are evaluated against experimental data obtained from the complex geometry and shear stress patterns offered by a mid-graft focal stenosis, where simulation results show good agreements with the experimental data.
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Affiliation(s)
- Minki Hwang
- Departments of Mechanical & Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Marc Garbey
- Department of Computer Science, University of Houston, Houston, Texas, United States of America
| | - Scott A. Berceli
- Department of Surgery, University of Florida College of Medicine, Gainesville, Florida, United States of America
- Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida, United States of America
| | - Rongling Wu
- Center for Statistical Genetics, Division of Biostatistics, Pennsylvania State University, Hershey, Pennsylvania, United States of America
| | - Zhihua Jiang
- Department of Surgery, University of Florida College of Medicine, Gainesville, Florida, United States of America
- Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida, United States of America
| | - Roger Tran-Son-Tay
- Departments of Mechanical & Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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