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Coronary Artery Radial Deformation and Velocity in Native and Stented Arteries. J Interv Cardiol 2022; 2022:5981027. [PMID: 35401063 PMCID: PMC8976594 DOI: 10.1155/2022/5981027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 03/12/2022] [Indexed: 11/30/2022] Open
Abstract
Introduction Coronary arteries are exposed to a variety of complex biomechanical forces during a normal cardiac cycle. These forces have the potential to contribute to coronary stent failure. Recent advances in stent design allow for the transmission of native pulsatile biomechanical forces in the stented vessel. However, there is a significant lack of evidence in a human model to measure vessel motion in native coronary arteries and stent conformability. Thus, we aimed to characterize and define coronary artery radial deformation and the effect of stent implantation on arterial deformation. Materials and Methods Intravascular ultrasound (IVUS) pullback DICOM images were obtained from human coronary arteries using a coronary ultrasound catheter. Using two-dimensional speckle tracking, coronary artery radial deformation was defined as the inward and outward displacement (mm) and velocity (cm/s) of the arterial wall during the cardiac cycle. These deformation values were obtained in native and third-generation drug-eluting stented artery segments. Results A total of 20 coronary artery segments were independently analyzed pre and poststent implantation for a total of 40 IVUS runs. Stent implantation impacted the degree of radial deformation and velocity. Mean radial deformation in native coronary arteries was 0.1230 mm ± 0.0522 mm compared to 0.0775 mm ± 0.0376 mm in stented vessels (p=0.0031). Mean radial velocity in native coronary arteries was 0.1194 cm/s ± 0.0535 cm/s compared to 0.0840 cm/s ± 0.0399 cm/s in stented vessels (p=0.0228). Conclusion In this in vivo analysis of third-generation stents, stent implantation attenuates normal human coronary deformation during the cardiac cycle. The implications of these findings on stent failure and improved clinical outcomes require further investigation.
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Adaptive coronary artery rotational motion through uncaging of a drug-eluting bioadaptor aiming to reduce stress on the coronary artery. CARDIOVASCULAR REVASCULARIZATION MEDICINE 2021; 39:52-57. [PMID: 34629284 DOI: 10.1016/j.carrev.2021.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 09/23/2021] [Accepted: 09/27/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND Caged drug-eluting stents impede natural coronary rotational motion and increase vessel stress, which can contribute towards adverse events. The DynamX™ Drug-Eluting Bioadaptor is a cobalt‑chromium platform with a novel mechanism that uncages the vessel after the bioresorbable coating resorbs over six months. This study aimed to analyze the effects of the rotational uncaging in a finite element analysis (FEA) model, validating its effect on coronary artery rotational motion through in-vivo stationary intravascular ultrasound (IVUS). METHODS Maximum Von Mises stresses were measured in an FEA model and compared for caged and uncaged bioadaptors. Stationary IVUS images from 20 patients enrolled in a single center were acquired post implantation and at 9-12-month follow-up to evaluate coronary artery rotational motion. RESULTS The FEA model showed that rotational uncaging of the bioadaptor reduces peak stress by 70%. In-vivo, the in-bioadaptor segment was significantly distorted post-implant compared to the native distal and proximal vessel, measured by IVUS: The sum of clockwise and counterclockwise rotational motion (net-effect rotational motion) was -2.7 ± 4.3° versus 0.5 ± 5.0° (proximal vessel), p = 0.036, and versus 0.2 ± 3.8° (distal vessel), p = 0.042. At follow up, when the bioadaptor had uncaged, the vessel returned towards its equilibrium (net-effect rotational motion -0.2 ± 5.6°), with no significant difference between the vessel segments. CONCLUSIONS In concurrence with the FEA observation, the in-vivo IVUS-analysis demonstrates that uncaging of the bioadaptor affects coronary artery rotational motion. The effect of these findings on reducing clinical events warrants further investigation.
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Wu X, Ono M, Kawashima H, Poon EKW, Torii R, Shahzad A, Gao C, Wang R, Barlis P, von Birgelen C, Reiber JHC, Bourantas CV, Tu S, Wijns W, Serruys PW, Onuma Y. Angiography-Based 4-Dimensional Superficial Wall Strain and Stress: A New Diagnostic Tool in the Catheterization Laboratory. Front Cardiovasc Med 2021; 8:667310. [PMID: 34222366 PMCID: PMC8249568 DOI: 10.3389/fcvm.2021.667310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/21/2021] [Indexed: 12/23/2022] Open
Abstract
A novel method for four-dimensional superficial wall strain and stress (4D-SWS) is derived from the arterial motion as pictured by invasive coronary angiography. Compared with the conventional finite element analysis of cardiovascular biomechanics using the estimated pulsatile pressure, the 4D-SWS approach can calculate the dynamic mechanical state of the superficial wall in vivo, which could be directly linked with plaque rupture or stent fracture. The validation of this approach using in silico models showed that the distribution and maximum values of superficial wall stress were similar to those calculated by conventional finite element analysis. The in vivo deformation was validated on 16 coronary arteries, from the comparison of centerlines predicted by the 4D-SWS approach against the actual centerlines reconstructed from angiograms at a randomly selected time-point, which demonstrated a good agreement of the centerline morphology between both approaches (scaling: 0.995 ± 0.018 and dissimilarity: 0.007 ± 0.014). The in silico vessel models with softer plaque and larger plaque burden presented more variation in mean lumen diameter and resulted in higher superficial wall stress. In more than half of the patients (n = 16), the maximum superficial wall stress was found at the proximal lesion shoulder. Additionally, in three patients who later suffered from acute coronary syndrome, the culprit plaque rupture sites co-localized with the site of highest superficial wall stress on their baseline angiography. These representative cases suggest that angiography-based superficial wall dynamics have the potential to identify coronary segments at high-risk of plaque rupture and fracture sites of implanted stents. Ongoing studies are focusing on identifying weak spots in coronary bypass grafts, and on exploring the biomechanical mechanisms of coronary arterial remodeling and aneurysm formation. Future developments involve integration of fast computational techniques to allow online availability of superficial wall strain and stress in the catheterization laboratory.
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Affiliation(s)
- Xinlei Wu
- Institute of Cardiovascular Development and Translational Medicine, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.,Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Smart Sensors Lab, National University of Ireland Galway (NUIG), Galway, Ireland
| | - Masafumi Ono
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Hideyuki Kawashima
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Eric K W Poon
- Department of Medicine, Melbourne Medical School, St Vincent's Hospital, University of Melbourne, Melbourne, VIC, Australia
| | - Ryo Torii
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Atif Shahzad
- Smart Sensors Lab, National University of Ireland Galway (NUIG), Galway, Ireland
| | - Chao Gao
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Department of Cardiology, Xijing Hospital, Xi'an, China
| | - Rutao Wang
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Department of Cardiology, Xijing Hospital, Xi'an, China
| | - Peter Barlis
- Department of Medicine, Melbourne Medical School, St Vincent's Hospital, University of Melbourne, Melbourne, VIC, Australia.,Faculty of Medicine, Dentistry Health Sciences, Melbourne Medical School, University of Melbourne, Melbourne, VIC, Australia
| | - Clemens von Birgelen
- Thoraxcentrum Twente, Medisch Spectrum Twente, Enschede, Netherlands.,Department of Health Technology and Services Research, Technical Medical Centre, Faculty of Behavioural, Management, and Social Sciences, University of Twente, Enschede, Netherlands
| | - Johan H C Reiber
- Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
| | - Christos V Bourantas
- Institute of Cardiovascular Science, University College London, London, United Kingdom.,Department of Cardiology, Barts Heart Centre, London, United Kingdom
| | - Shengxian Tu
- School of Biomedical Engineering, Biomedical Instrument Institute, Shanghai Jiao Tong University, Shanghai, China
| | - William Wijns
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Smart Sensors Lab, National University of Ireland Galway (NUIG), Galway, Ireland
| | - Patrick W Serruys
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland.,Imperial College London, National Heart and Lung Institute, London, United Kingdom
| | - Yoshinobu Onuma
- Department of Cardiology, National University of Ireland Galway (NUIG), Galway, Ireland
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McCallinhart PE, Scandling BW, Trask AJ. Coronary remodeling and biomechanics: Are we going with the flow in 2020? Am J Physiol Heart Circ Physiol 2020; 320:H584-H592. [PMID: 33185115 DOI: 10.1152/ajpheart.00634.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Under normal conditions, coronary blood flow (CBF) provides critical blood supply to the myocardium so that it can appropriately meet the metabolic demands of the body. Dogmatically, there exist several known regulators and modulators of CBF that include local metabolites and neurohormonal factors that can influence the function of the coronary circulation. In disease states such as diabetes and myocardial ischemia, these regulators are impaired or shifted such that CBF is reduced. Although functional considerations have been and continued to be well studied, more recent evidence builds upon established studies that collectively suggest that the relative roles of coronary structure, biomechanics, and the influence of cardiac biomechanics via extravascular compression may also play a significant role in dictating CBF. In this mini review, we discuss these regulators of CBF under normal and pathophysiological conditions and their potential influence on the control of CBF.
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Affiliation(s)
- Patricia E McCallinhart
- Center for Cardiovascular Research, The Heart Center, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, Ohio
| | - Benjamin W Scandling
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio.,Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Aaron J Trask
- Center for Cardiovascular Research, The Heart Center, The Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, Ohio.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio
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Zhu L, Pan Z, Li Z, Chang Y, Zhu Y, Yan F, Tu S, Yang W. Can the Wall Shear Stress Values of Left Internal Mammary Artery Grafts during the Perioperative Period Reflect the One-Year Patency? Thorac Cardiovasc Surg 2020; 68:723-729. [PMID: 32937666 DOI: 10.1055/s-0040-1714385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE The left internal mammary artery (LIMA) is the preferred graft for coronary artery bypass grafting, but the reasoning for LIMA occlusion is unclear. We sought to examine whether the wall shear stress (WSS) values of LIMA grafts during the perioperative period reflected the 1-year patency by using combining computational fluid dynamics (CFD) and coronary computed tomography angiography (CCTA) images. METHODS CCTA was performed in 233 patients with LIMA graft perioperatively and 1 year later from October 2014 to May 2017. LIMA occlusion was detected in six patients at the 1-year follow-up CCTA. Two patients were excluded due to poor imaging quality. The remaining four patients were enrolled as occlusive (OCC) group, and eight patients with patent LIMA were recruited as patent (PAT) group. The WSS values of LIMA during perioperative period were calculated. LIMA graft was artificially divided into three even segments, proximal (pLIMA), middle (mLIMA) and distal (dLIMA) segments. The independent samples t-test and the Student-Newman-Keuls test were used. RESULTS The WSS values of dLIMA were significantly higher in the PAT group than in the OCC group (4.43 vs. 2.56, p < 0.05). The WSS values of dLIMA in the PAT group were significantly higher than pLIMA, which was absent in the OCC group. CONCLUSIONS A higher WSS value of the distal segment of LIMA and a higher WSS value of the distal segment compared with the proximal segment of LIMA in the PAT were observed; this tendency might be helpful in predicting the 1-year patency of LIMA.
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Affiliation(s)
- Lan Zhu
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zilai Pan
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zehang Li
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yunxiao Chang
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yunpeng Zhu
- Department of Cardiac Surgery, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Fuhua Yan
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shengxian Tu
- Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Wenjie Yang
- Department of Radiology, Ruijin Hospital affiliated to School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Bazylev VV, Rosseĭkin EV, Radzhabov DA, Mikuliak AI. Results of flowmetric assessment of composite Y-grafts and autovenous coronary artery bypass grafts. ANGIOLOGII︠A︡ I SOSUDISTAI︠A︡ KHIRURGII︠A︡ = ANGIOLOGY AND VASCULAR SURGERY 2020; 26:52-59. [PMID: 32597885 DOI: 10.33529/angi02020210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM The purpose of the study was to perform intraoperative assessment of blood flow in coronary bypass grafts of the 'first' and 'third' order according to Calafiore A.M. with the help of the TTFM technique and to compare the obtained results. PATIENTS AND METHODS This retrospective, single-centre study enrolled a total of 222 patients subjected to coronary artery bypass grafting (CABG) from January to November 2017. Depending on the type of bypass grafting of the posterior interventricular artery (PIVA), the patients were divided into 2 groups. Group One consisted of 108 patients undergoing bypass grafting of the PIVA with the help of combined Y-grafts from the right internal thoracic artery (RTIA). Group Two was composed of 114 patients subjected to autovenous coronary artery bypass grafting of the PIVA. Blood flow was assessed with the help of the VeriQ MediStim® flowmeter after termination of extracorporeal circulation (ECC), at systolic pressure of 100-110 mm Hg. The parameters of blood flow were assessed using the 1.5- and 2-mm probes. In a specially designed protocol we registered the type of the shunt, the bypassed artery, and values of flowmetry parameters. We also evaluated the pattern of the flowmetric curve according to Takemi Handa et al. RESULTS: The obtained findings revealed a statistically significant difference in the values of Qmean (p=0.001), with the PI values in the groups not statistically differing (p=0.14). Thus, in patients with similar parameters influencing the volumetric velocity of blood flow (the degree of proximal stenosis, diameter of the bypassed artery, mean systolic AP and HR) the value of Qmean was higher in the group with coronary artery bypass grafting (CABG), i. e., in the group of the 'first-order' conduits. Therefore, an autovein directly anastomosed to the aorta experiences grater haemodynamic overload, which completely confirms the theory of Calafiore A.M. CONCLUSION First-order conduits (CABG) appear to experience greater wall strain because of greater haemodynamic overload as compared with third-order conduits (Y-grafts). A composite Y-graft may be an alternative technique of bypass grafting of the basin of the right coronary artery (RCA). A composite Y-graft has greater resistance to wall shear stress than an autovein anastomosed to the aorta.
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Affiliation(s)
- V V Bazylev
- Federal Centre of Cardiovascular Surgery under the RF Ministry of Public Health, Penza, Russia
| | - E V Rosseĭkin
- Federal Centre of Cardiovascular Surgery under the RF Ministry of Public Health, Penza, Russia
| | - D A Radzhabov
- Federal Centre of Cardiovascular Surgery under the RF Ministry of Public Health, Penza, Russia
| | - A I Mikuliak
- Federal Centre of Cardiovascular Surgery under the RF Ministry of Public Health, Penza, Russia
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7
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Wadey K, Lopes J, Bendeck M, George S. Role of smooth muscle cells in coronary artery bypass grafting failure. Cardiovasc Res 2019; 114:601-610. [PMID: 29373656 DOI: 10.1093/cvr/cvy021] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 01/22/2018] [Indexed: 01/30/2023] Open
Abstract
Atherosclerosis is the underlying pathology of many cardiovascular diseases. The formation and rupture of atherosclerotic plaques in the coronary arteries results in angina and myocardial infarction. Venous coronary artery bypass grafts are designed to reduce the consequences of atherosclerosis in the coronary arteries by diverting blood flow around the atherosclerotic plaques. However, vein grafts suffer a high failure rate due to intimal thickening that occurs as a result of vascular cell injury and activation and can act as 'a soil' for subsequent atherosclerotic plaque formation. A clinically-proven method for the reduction of vein graft intimal thickening and subsequent major adverse clinical events is currently not available. Consequently, a greater understanding of the underlying mechanisms of intimal thickening may be beneficial for the design of future therapies for vein graft failure. Vein grafting induces inflammation and endothelial cell damage and dysfunction, that promotes vascular smooth muscle cell (VSMC) migration, and proliferation. Injury to the wall of the vein as a result of grafting leads to the production of chemoattractants, remodelling of the extracellular matrix and cell-cell contacts; which all contribute to the induction of VSMC migration and proliferation. This review focuses on the role of altered behaviour of VSMCs in the vein graft and some of the factors which critically lead to intimal thickening that pre-disposes the vein graft to further atherosclerosis and re-occurrence of symptoms in the patient.
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Affiliation(s)
- Kerry Wadey
- Bristol Medical School, Research Floor Level 7, Bristol Royal Infirmary, Bristol BS2 8HW, UK
| | - Joshua Lopes
- Translational Biology and Engineering Program, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Michelle Bendeck
- Translational Biology and Engineering Program, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Sarah George
- Bristol Medical School, Research Floor Level 7, Bristol Royal Infirmary, Bristol BS2 8HW, UK
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Gooch KJ, Firstenberg MS, Shrefler BS, Scandling BW. Biomechanics and Mechanobiology of Saphenous Vein Grafts. J Biomech Eng 2019; 140:2666246. [PMID: 29222565 DOI: 10.1115/1.4038705] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Indexed: 11/08/2022]
Abstract
Within several weeks of use as coronary artery bypass grafts (CABG), saphenous veins (SV) exhibit significant intimal hyperplasia (IH). IH predisposes vessels to thrombosis and atherosclerosis, the two major modes of vein graft failure. The fact that SV do not develop significant IH in their native venous environment coupled with the rapidity with which they develop IH following grafting into the arterial circulation suggests that factors associated with the isolation and preparation of SV and/or differences between the venous and arterial environments contribute to disease progression. There is strong evidence suggesting that mechanical trauma associated with traditional techniques of SV preparation can significantly damage the vessel and might potentially reduce graft patency though modern surgical techniques reduces these injuries. In contrast, it seems possible that modern surgical technique, specifically endoscopic vein harvest, might introduce other mechanical trauma that could subtly injure the vein and perhaps contribute to the reduced patency observed in veins harvested using endoscopic techniques. Aspects of the arterial mechanical environment influence remodeling of SV grafted into the arterial circulation. Increased pressure likely leads to thickening of the medial wall but its role in IH is less clear. Changes in fluid flow, including increased average wall shear stress, may reduce IH while disturbed flow likely increase IH. Nonmechanical stimuli, such as exposure to arterial levels of oxygen, may also have a significant but not widely recognized role in IH. Several potentially promising approaches to alter the mechanical environment to improve graft patency are including extravascular supports or altered graft geometries are covered.
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Affiliation(s)
- Keith J Gooch
- Department of Biomedical Engineering, The Ohio State University, 290 Bevis Hall 1080 Carmack Drive, Columbus, OH 43210.,Davis Heart Lung Research Institute, The Ohio State University, Columbus, OH 43210 e-mail:
| | - Michael S Firstenberg
- Surgery and Integrative Medicine, Northeast Ohio Medical Universities, Akron, OH 44309
| | - Brittany S Shrefler
- Department of Internal Medicine, The Ohio State University, Columbus, OH 43210
| | - Benjamin W Scandling
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210
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Challa KK, Kansal MM, Frazin L, Nikanorov A, Kohler R, Martinsen BJ, Vidovich MI. Coronary artery rotation in native and stented porcine coronary arteries. Catheter Cardiovasc Interv 2018; 91:1092-1100. [PMID: 28836331 DOI: 10.1002/ccd.27247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/20/2017] [Accepted: 07/22/2017] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Coronary arteries are exposed to several complex biomechanical forces during the cardiac cycle. These biomechanical forces potentially contribute to both native coronary artery disease, development of atherosclerosis and eventual stent failure. The aim of the present study was to characterize and define coronary artery axial rotation and the effect of stent implantation on this biomechanical factor. METHODS Intravascular ultrasound (IVUS) images were obtained from porcine coronary arteries and analyzed in ultrasound analysis software used to evaluate myocardial strain and torsion in echocardiography. In this study the software was utilized for a novel application to evaluate coronary artery rotation and time-to-peak (TTP) rotation in porcine coronary arteries. Clockwise (CW) and counterclockwise (CCW) rotation of coronary arteries during the cardiac cycle and (TTP) rotation were measured. RESULTS A total of 11 (4 LAD, 4 LCX, 3 RCA) coronary artery segments were independently analyzed pre- and post-stent implantation for a total of 22 IVUS runs. CW and CCW rotation and TTP varied widely within coronary artery segments and between different coronary arteries. Stent implantation impacted degree, direction and TTP of coronary rotation. Measurement reliability was assessed and the intraclass correlation coefficient for maximum average CCW was 0.990 (95% confidence interval 0.980-0.996, P < 0.0001), indicating excellent agreement. CONCLUSIONS Coronary arteries display wide spectrum of CW and CCW rotation during the cardiac cycle. Coronary stents impact the degree and direction of coronary artery rotation. The implications of these findings on development of atherosclerosis and stent failure require further investigation.
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Affiliation(s)
- Karthik K Challa
- Department of Medicine, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Division of Cardiology, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Department of Veterans Affairs, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois
| | - Mayank M Kansal
- Department of Medicine, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Division of Cardiology, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Department of Veterans Affairs, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois
| | - Leon Frazin
- Department of Medicine, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Division of Cardiology, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Department of Veterans Affairs, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois
| | - Alex Nikanorov
- Clinical and Scientific Affairs, Cardiovascular Systems, Inc, St. Paul, Minnesota, 55112
| | - Robert Kohler
- Clinical and Scientific Affairs, Cardiovascular Systems, Inc, St. Paul, Minnesota, 55112
| | - Brad J Martinsen
- Clinical and Scientific Affairs, Cardiovascular Systems, Inc, St. Paul, Minnesota, 55112
| | - Mladen I Vidovich
- Department of Medicine, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Division of Cardiology, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois.,Department of Veterans Affairs, University of Illinois at Chicago, Jesse Brown VA Medical Center, Chicago, Illinois
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10
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Mattson JM, Zhang Y. Structural and Functional Differences Between Porcine Aorta and Vena Cava. J Biomech Eng 2018; 139:2612941. [PMID: 28303272 DOI: 10.1115/1.4036261] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 12/14/2022]
Abstract
Elastin and collagen fibers are the major load-bearing extracellular matrix (ECM) constituents of the vascular wall. Arteries function differently than veins in the circulatory system; however as a result from several treatment options, veins are subjected to sudden elevated arterial pressure. It is thus important to recognize the fundamental structure and function differences between a vein and an artery. Our research compared the relationship between biaxial mechanical function and ECM structure of porcine thoracic aorta and inferior vena cava. Our study suggests that aorta contains slightly more elastin than collagen due to the cyclical extensibility, but vena cava contains almost four times more collagen than elastin to maintain integrity. Furthermore, multiphoton imaging of vena cava showed longitudinally oriented elastin and circumferentially oriented collagen that is recruited at supraphysiologic stress, but low levels of strain. However in aorta, elastin is distributed uniformly, and the primarily circumferentially oriented collagen is recruited at higher levels of strain than vena cava. These structural observations support the functional finding that vena cava is highly anisotropic with the longitude being more compliant and the circumference stiffening substantially at low levels of strain. Overall, our research demonstrates that fiber distributions and recruitment should be considered in addition to relative collagen and elastin contents. Also, the importance of accounting for the structural and functional differences between arteries and veins should be taken into account when considering disease treatment options.
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Affiliation(s)
- Jeffrey M Mattson
- Department of Mechanical Engineering, Boston University, Boston, MA 02215 e-mail:
| | - Yanhang Zhang
- Department of Mechanical Engineering, Department of Biomedical Engineering, Boston University, 110 Cummington Mall, Boston, MA 02215 e-mail:
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11
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Drug-eluting stents appear superior to bare metal stents for vein-graft PCI in vessels up to a stent diameter of 4 mm. Heart Int 2016; 11:e17-e24. [PMID: 27924213 PMCID: PMC5072290 DOI: 10.5301/heartint.5000228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2016] [Indexed: 12/03/2022] Open
Abstract
Background Research trials have shown improved short-term outcome with drug-eluting stents (DES) over bare metal stents (BMS) in saphenous vein graft (SVG) percutaneous coronary intervention (PCI), primarily by reducing target vessel revascularization (TVR) for in-stent restenosis. We compared the outcomes in patients undergoing SVG stent implantation treated with DES or BMS. In exploratory analyses we investigated the influence of stent generation and diameter. Methods Data were obtained from a prospective database of 657 patients who underwent PCI for SVG lesions between 2003 and 2011. A total of 344 patients had PCI with BMS and 313 with DES. Propensity scores were developed based on 15 observed baseline covariates in a logistic regression model with stent type as the dependent variable. The nearest-neighbour-matching algorithm with Greedy 5-1 Digit Matching was used to produce two patient cohorts of 313 patients each. We assessed major adverse cardiac events (MACE) out to a median of 3.3 years (interquartile range: 2.1-4.1). MACE was defined as all-cause mortality, myocardial infarction (MI), TVR and stroke. Results There was a significant difference in MACE between the two groups in favour of DES (17.9% DES vs. 31.2% BMS group; p = 0.0017) over the 5-year follow-up period. MACE was driven by increased TVR in the BMS group. There was no difference in death, MI or stroke. Adjusted Cox analysis confirmed a decreased risk of MACE for DES compared with BMS 0.75 (95% confidence interval (CI) 0.52-0.94), with no difference in the hazard of all-cause mortality (hazard ratio: 1.08; 95% CI: 0.77-1.68). However, when looking at stent diameters greater than 4 mm, no difference was seen in MACE rates between BMS and DES. Conclusions Overall in our cohort of patients who had PCI for SVG disease, DES use resulted in lower MACE rates compared with BMS over a 5-year follow-up period; however, for stent diameters over 4 mm no difference in MACE rates was seen.
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12
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Erndt-Marino JD, Becerra-Bayona S, McMahon RE, Goldstein AS, Hahn MS. Cell layer-electrospun mesh composites for coronary artery bypass grafts. J Biomed Mater Res A 2016; 104:2200-9. [PMID: 27101019 DOI: 10.1002/jbm.a.35753] [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] [Received: 02/01/2016] [Revised: 04/15/2016] [Accepted: 04/19/2016] [Indexed: 11/09/2022]
Abstract
This work investigates the potential of cell layer-electrospun mesh constructs as coronary artery bypass grafts. These cell-mesh constructs were generated by first culturing a confluent layer of 10T½ smooth muscle progenitor cells on a high strength electrospun mesh with uniaxially aligned fibers. Cell-laden mesh sheets were then wrapped around a cylindrical mandrel such that the mesh fibers were aligned circumferentially. The resulting multi-layered constructs were then cultured for 4 wks in media supplemented with TGF-β1 and ascorbic acid to support 10T½ differentiation toward a smooth muscle cell-like fate as well as to support elastin and collagen production. The underlying hypothesis of this work was that extracellular matrix (ECM) deposited by the cell layers would act as an adhesive agent between the individual mesh layers, providing strength to the construct as well as a source for structural elasticity at low strains. In addition, the structural anisotropy of the mesh would inherently guide desired circumferential cell and ECM alignment. Results demonstrate that the cell-mesh constructs exhibited a J-shaped circumferential stress-strain response similar to that of native coronary artery, while also displaying acceptable tensile strength. Furthermore, associated 10T½ cells and deposited collagen fibers showed a high degree of circumferential alignment. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2200-2209, 2016.
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Affiliation(s)
- Josh D Erndt-Marino
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
| | - Silvia Becerra-Bayona
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
| | - Rebecca E McMahon
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, 77843
| | - Aaron S Goldstein
- Department of Chemical Engineering, Virginia Polytechnic and State University, Blacksburg, Virginia, 24061
| | - Mariah S Hahn
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12180
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Pashneh-Tala S, MacNeil S, Claeyssens F. The Tissue-Engineered Vascular Graft-Past, Present, and Future. TISSUE ENGINEERING PART B-REVIEWS 2015; 22:68-100. [PMID: 26447530 PMCID: PMC4753638 DOI: 10.1089/ten.teb.2015.0100] [Citation(s) in RCA: 446] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiovascular disease is the leading cause of death worldwide, with this trend predicted to continue for the foreseeable future. Common disorders are associated with the stenosis or occlusion of blood vessels. The preferred treatment for the long-term revascularization of occluded vessels is surgery utilizing vascular grafts, such as coronary artery bypass grafting and peripheral artery bypass grafting. Currently, autologous vessels such as the saphenous vein and internal thoracic artery represent the gold standard grafts for small-diameter vessels (<6 mm), outperforming synthetic alternatives. However, these vessels are of limited availability, require invasive harvest, and are often unsuitable for use. To address this, the development of a tissue-engineered vascular graft (TEVG) has been rigorously pursued. This article reviews the current state of the art of TEVGs. The various approaches being explored to generate TEVGs are described, including scaffold-based methods (using synthetic and natural polymers), the use of decellularized natural matrices, and tissue self-assembly processes, with the results of various in vivo studies, including clinical trials, highlighted. A discussion of the key areas for further investigation, including graft cell source, mechanical properties, hemodynamics, integration, and assessment in animal models, is then presented.
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Affiliation(s)
- Samand Pashneh-Tala
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
| | - Sheila MacNeil
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
| | - Frederik Claeyssens
- Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield , Broad Lane, Sheffield, United Kingdom
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Impact of top end anastomosis design on patency and flow stability in coronary artery bypass grafting. Heart Vessels 2015; 31:643-8. [DOI: 10.1007/s00380-015-0680-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 03/06/2015] [Indexed: 11/25/2022]
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Singh C, Wang X. A new design concept for knitted external vein-graft support mesh. J Mech Behav Biomed Mater 2015; 48:125-133. [PMID: 25916819 DOI: 10.1016/j.jmbbm.2015.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 11/24/2022]
Abstract
Autologous vein-graft failure significantly limits the long-term efficacy of coronary artery bypass procedures. The major cause behind this complication is biomechanical mismatch between the vein and coronary artery. The implanted vein experiences a sudden increase (10-12 fold) in luminal pressures. The resulting vein over-distension or 'ballooning' initiates wall thickening phenomenon and ultimate occlusion. Therefore, a primary goal in improving the longevity of a coronary bypass procedure is to inhibit vein over-distension using mechanical constriction. The idea of using an external vein-graft support mesh has demonstrated sustained benefits and wide acceptance in experimental studies. Nitinol based knitted structures have offered more promising mechanical features than other mesh designs owing to their unique loosely looped construction. However, the conventional plain knit construction still exhibits limitations (radial compliance, deployment ease, flexibility, and bending stresses) which limit this design from proving its real clinical advantage. The new knitted mesh design presented in this study is based on the concept of composite knitting utilising high modulus (nitinol and polyester) and low modulus (polyurethane) material components. The experimental comparison of the new design with a plain knit design demonstrated significant improvement in biomechanical (compliance, flexibility, extensibility, viscoelasticity) and procedural (deployment limit) parameters. The results are indicative of the promising role of new mesh in restoring the lost compliance and pulsatility of vein-graft at high arterial pressures. This way it can assist in controlled vein-graft remodelling and stepwise restoration of vein mechanical homoeostasis. Also, improvement in deployment limit parameter offers more flexibility for a surgeon to use a wide range of vein diameters, which may otherwise be rendered unusable for a plain knit mesh.
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Affiliation(s)
- Charanpreet Singh
- Australian Future Fibres Research and Innovation Centre, Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216, Australia
| | - Xungai Wang
- Australian Future Fibres Research and Innovation Centre, Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216, Australia; School of Textile Science and Engineering, Wuhan Textile University, Wuhan 430073, China.
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Abstract
Coronary artery disease is recognized as a major health problem worldwide, particularly because of the associated morbidity and mortality. Coronary artery bypass grafting has been an established mainstay in the treatment of this disease for almost half a century and is arguably the most intensively studied surgical procedure ever undertaken. Because of its unique properties, the human internal mammary artery has long been considered the best graft to use in this type of surgery. Previous studies have shown several advantages of this graft compared with others, that is, lower incidence of atherosclerosis. However, few comparative studies on the reactivity of this artery have been published. Moreover, these studies usually focus on isolated cardiovascular risk factors rather than combined risk factors. In fact, patients who require coronary revascularization usually present multiple risk factors, which can interfere with several pathways of regulation of vascular function, namely endothelial function. Several diseases and cardiovascular risk factors have been shown to interfere with endothelial function, promoting the production of vasoconstrictors, inhibiting the production of vasodilators, or both, and thus eventually leading to endothelial dysfunction. Therefore, it is of great interest to study the endothelial function, particularly of the human internal mammary artery, in the presence of combined cardiovascular risk factors and concomitant diseases. Many techniques have been developed to assess the endothelial function, in particular, studies on isolated arteries, as well as spectroscopic, electrochemical, and immunological methods, among others.
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Sayed Razavi M, Shirani E. Development of a general method for designing microvascular networks using distribution of wall shear stress. J Biomech 2013; 46:2303-9. [DOI: 10.1016/j.jbiomech.2013.06.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 06/02/2013] [Accepted: 06/04/2013] [Indexed: 11/25/2022]
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Piola M, Prandi F, Bono N, Soncini M, Penza E, Agrifoglio M, Polvani G, Pesce M, Fiore GB. A compact and automated ex vivo vessel culture system for the pulsatile pressure conditioning of human saphenous veins. J Tissue Eng Regen Med 2013; 10:E204-15. [PMID: 23897837 DOI: 10.1002/term.1798] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/29/2013] [Accepted: 07/08/2013] [Indexed: 11/05/2022]
Abstract
Saphenous vein (SV) graft disease represents an unresolved problem in coronary artery bypass grafting (CABG). After CABG, a progressive remodelling of the SV wall occurs, possibly leading to occlusion of the lumen, a process termed 'intima hyperplasia' (IH). The investigation of cellular and molecular aspects of IH progression is a primary end-point toward the generation of occlusion-free vessels that may be used as 'life-long' grafts. While animal transplantation models have clarified some of the remodelling factors, the pathology of human SV is far from being understood. This is also due to the lack of devices able to reproduce the altered mechanical load encountered by the SV after CABG. This article describes the design of a novel ex vivo vein culture system (EVCS) capable of replicating the altered pressure pattern experienced by SV after CABG, and reports the results of a preliminary biomechanical conditioning experimental campaign on SV segments. The EVCS applied a CAGB-like pressure (80-120 mmHg) or a venous-like perfusion (3 ml/min, 5 mmHg) conditioning to the SVs, keeping the segments viable in a sterile environment during 7 day culture experiments. After CABG-like pressure conditioning, SVs exhibited a decay of the wall thickness, an enlargement of the luminal perimeter, a rearrangement of the muscle fibres and partial denudation of the endothelium. Considering these preliminary results, the EVCS is a suitable system to study the mechanical attributes of SV graft disease, and its use, combined with a well-designed biological protocol, may be of help in elucidating the cellular and molecular mechanisms involved in SV graft disease.
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Affiliation(s)
- Marco Piola
- Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milan, Italy
| | - Francesca Prandi
- Laboratorio di Ingegneria Tissutale Cardiovascolare, Centro Cardiologico Monzino-IRCCS, Milan, Italy
| | - Nina Bono
- Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milan, Italy
| | - Monica Soncini
- Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Milan, Italy
| | - Eleonora Penza
- II Divisione di Cardiochirurgia, Centro Cardiologico Monzino-IRCCS, Milan, Italy
| | - Marco Agrifoglio
- Dipartimento di Scienze Cliniche e di Comunità, Università di Milano, Milan, Italy
| | - Gianluca Polvani
- Dipartimento di Scienze Cliniche e di Comunità, Università di Milano, Milan, Italy
| | - Maurizio Pesce
- Laboratorio di Ingegneria Tissutale Cardiovascolare, Centro Cardiologico Monzino-IRCCS, Milan, Italy
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Keyes JT, Lockwood DR, Utzinger U, Montilla LG, Witte RS, Vande Geest JP. Comparisons of planar and tubular biaxial tensile testing protocols of the same porcine coronary arteries. Ann Biomed Eng 2012; 41:1579-91. [PMID: 23132151 DOI: 10.1007/s10439-012-0679-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 10/09/2012] [Indexed: 01/13/2023]
Abstract
To identify the orthotropic biomechanical behavior of arteries, researchers typically perform stretch-pressure-inflation tests on tube-form arteries or planar biaxial testing of splayed sections. We examined variations in finite element simulations (FESs) driven from planar or tubular testing of the same coronary arteries to determine what differences exist when picking one testing technique vs. another. Arteries were tested in tube-form first, then tested in planar-form, and fit to a Fung-type strain energy density function. Afterwards, arteries were modeled via finite element analysis looking at stress and displacement behavior in different scenarios (e.g., tube FESs with tube- or planar-driven constitutive models). When performing FESs of tube inflation from a planar-driven constitutive model, pressure-diameter results had an error of 12.3% compared to pressure-inflation data. Circumferential stresses were different between tube- and planar-driven pressure-inflation models by 50.4% with the planar-driven model having higher stresses. This reduced to 3.9% when rolling the sample to a tube first with planar-driven properties, then inflating with tubular-driven properties. Microstructure showed primarily axial orientation in the tubular and opening-angle configurations. There was a shift towards the circumferential direction upon flattening of 8.0°. There was also noticeable collagen uncrimping in the flattened tissue.
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Affiliation(s)
- Joseph T Keyes
- Graduate Interdisciplinary Program in Biomedical Engineering, The University of Arizona, P.O. Box 210119, Tucson, AZ 85721-0119, USA
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Impact of competitive flow on hemodynamics in coronary surgery: numerical study of ITA-LAD model. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:356187. [PMID: 22997536 PMCID: PMC3444941 DOI: 10.1155/2012/356187] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Competitive flow from native coronary artery is considered as a major factor in the failure of the coronary artery bypass grafts. However, the physiological effects are not very clear. The aim is to research the impact of competitive flow caused by different left anterior descending (LAD) artery stenosis degrees on hemodynamics in internal thoracic artery (ITA) bypass graft. An idealized ITA-LAD model was built in CAD tools. The degree of the competitive flow was divided into five classes according to different LAD stenosis degrees: higher (no stenosis), secondary (30% stenosis), reduced (50% stenosis), lower (75% stenosis) and no competitive flow (fully stenosis). Finite volume method was employed for the numerical simulation. The flow velocity distributions, wall shear stress and oscillatory shear index were analyzed. Results showed that higher competitive flow in the bypass graft would produce unbeneficial wall shear stress distribution associating with endothelial dysfunction and subsequent graft failure. The coronary bypass graft surgery was preferred to be carried out when the LAD stenosis was higher than 75%.
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21
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Aksut M, Koksal C, Kocamaz O, Aksoy E, Kara I, Onk A, Ozkaynak B. Should right coronary bypass grafts be anastomosed proximal or distal to the crux? A comparison of graft patencies. Ann Thorac Cardiovasc Surg 2012; 18:331-7. [PMID: 22673608 DOI: 10.5761/atcs.oa.11.01783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
AIM Late occlusion of bypass grafts is one of the main issues associated with long-term survival after coronary artery bypass grafting (CABG) surgery. Left coronary system is generally revascularized using arterial conduits, whereas saphenous venous grafts are used for right coronary system. We investigated the prognostic factors that are related to the patency and risk of occlusion of saphenous venous grafts used for revascularization of diseased right coronary arteries. PATIENTS AND METHOD 92 patients who underwent CABG operation including a right coronary artery (RCA) bypass using saphenous venous graft (SVG) between January 2003 and July 2010 were evaluated retrospectively. Mean time of follow up was 66.9 ± 27.2 months (range 104-13 months). Grafts patencies were investigated using coronary angiography, and associated risk factors for mortality and morbidity were determined during the mid-term and long-term follow up. During the data collection phase, a significant association was noticed between patency of right coronary bypass grafts and site of distal anastomoses on RCA. Thus, patients were divided into two groups, according to the site of anastomosis. Right coronary anastomoses were performed either proximal (Group A, n = 44) or distal (Group B, n = 46) to the crux of the RCA (PDA). RESULTS Patency rates were similar in-group A (50% occluded and 50% patent) whereas patency rates were significantly higher in-group B (occluded 16.7%, patent 83.3%, p = 0.001). Mean age was significantly higher in-group A compared to Group B (p <0.05); however, there was no statistically significant difference between the two groups with regard to risk factors associated with cardiovascular disease (p >0.05). Also, mean diameter of the target vessel was significantly higher in-group A (p <0.01). CONCLUSION Based on the results of our study we suggest that even though an appropriate segment for anastomosis is available proximal to the crux of the RCA, right posterior descending artery (PDA) should be preferred for revascularization when RCA is the target vessel in CABG.
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Affiliation(s)
- Mehmet Aksut
- Kartal Kouyolu Training and Research Hospital, Cardiovascular Surgery Clinic, Istanbul, Turkey
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23
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Choi JS, Hong SC, Kwon HM, Suh SH, Lee JS. Influences of Geometric Configurations of Bypass Grafts on Hemodynamics in End-to-Side Anastomosis. THE KOREAN JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY 2012; 44:89-98. [PMID: 22263134 PMCID: PMC3249301 DOI: 10.5090/kjtcs.2011.44.2.89] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 03/17/2011] [Accepted: 03/17/2011] [Indexed: 11/22/2022]
Abstract
Background Although considerable efforts have been made to improve the graft patency in coronary artery bypass surgery, the role of biomechanical factors remains underrecognized. The aim of this study is to investigate the influences of geometric configurations of the bypass graft on hemodynamic characteristics in relation to anastomosis. Materials and Methods The Numerical analysis focuses on understanding the flow patterns for different values of inlet and distal diameters and graft angles. The Blood flow field is treated as a two-dimensional incompressible laminar flow. A finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as a constitutive equation for blood. In an attempt to obtain the optimal aorto-coronary bypass conditions, the blood flow characteristics are analyzed using in vitro models of the end-to-side anastomotic angles of 45°, 60° and 90°. To find the optimal graft configurations, the mass flow rates at the outlets of the four models are compared quantitatively. Results This study finds that Model 3, whose bypass diameter is the same as the inlet diameter of the stenosed coronary artery, delivers the largest amount of blood and the least pressure drop along the arteries. Conclusion Biomechanical factors are speculated to contribute to the graft patency in coronary artery bypass grafting.
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Affiliation(s)
- Jae-Sung Choi
- Deptartment of Thoracic and Cardiovascular Surgery, Seoul National University Boramae Hospital, Korea
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Anastasiou AD, Spyrogianni AS, Koskinas KC, Giannoglou GD, Paras SV. Experimental investigation of the flow of a blood analogue fluid in a replica of a bifurcated small artery. Med Eng Phys 2011; 34:211-8. [PMID: 21824798 DOI: 10.1016/j.medengphy.2011.07.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 05/31/2011] [Accepted: 07/13/2011] [Indexed: 11/30/2022]
Abstract
The scope of this work is to study the pulsatile flow of a blood mimicking fluid in a micro channel that simulates a bifurcated small artery, in which the Fahraeus-Lindqvist effect is insignificant. An aqueous glycerol solution with small amounts of xanthan gum was used for simulating viscoelastic properties of blood and in vivo flow conditions were reproduced. Local flow velocities were measured using micro Particle Image Velocimetry (μ-PIV). From the measured velocity distributions, the wall shear stress (WSS) and its variation during a pulse were estimated. The Reynolds numbers employed are relatively low, i.e. similar to those prevailing during blood flow in small arteries. Experiments both with a Newtonian and a non-Newtonian fluid (having asymptotic viscosity equal to the viscosity of the Newtonian one) proved that the common assumption that blood behaves as a Newtonian fluid is not valid for blood flow in small arteries. It was also shown that the outer wall of the bifurcation, which is exposed to a lower WSS, is more predisposed to atherosclerotic plaque formation. Moreover, this region in small vessels is shorter than the one in large arteries, as the developed secondary flow decays faster. Finally, the WSS values in small arteries were found to be lower than those in large ones.
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Affiliation(s)
- A D Anastasiou
- Laboratory of Chemical Process and Plant Design, Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece
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McMahon RE, Qu X, Jimenez-Vergara AC, Bashur CA, Guelcher SA, Goldstein AS, Hahn MS. Hydrogel-electrospun mesh composites for coronary artery bypass grafts. Tissue Eng Part C Methods 2011; 17:451-61. [PMID: 21083438 DOI: 10.1089/ten.tec.2010.0427] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aim of the present study was to investigate the potential of hydrogel-electrospun mesh hybrid scaffolds as coronary artery bypass grafts. The circumferential mechanical properties of blood vessels modulate a broad range of phenomena, including vessel stress and mass transport, which, in turn, have a critical impact on cardiovascular function. Thus, coronary artery bypass grafts should mimic key features of the nonlinear stress-strain behavior characteristic of coronary arteries. In native arteries, this J-shaped circumferential stress-strain curve arises primarily from initial load transfer to low stiffness elastic fibers followed by progressive recruitment and tensing of higher stiffness arterial collagen fibers. This nonlinear mechanical response is difficult to achieve with a single-component scaffold while simultaneously meeting the suture retention strength and tensile strength requirements of an implantable graft. For instance, although electrospun scaffolds have a number of advantages for arterial tissue engineering, including relatively high tensile strengths, tubular mesh constructs formed by conventional electrospinning methods do not generally display biphasic stress-strain curves. In the present work, we demonstrate that a multicomponent scaffold comprised of polyurethane electrospun mesh layers (intended to mimic the role of arterial collagen fibers) bonded together by a fibrin hydrogel matrix (designed to mimic the role of arterial elastic fibers) results in a composite construct which retains the high tensile strength and suture retention strength of electrospun mesh but which displays a J-shaped mechanical response similar to that of native coronary artery. Moreover, we show that these hybrid constructs support cell infiltration and extracellular matrix accumulation following 12-day exposure to continuous cyclic distension.
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Affiliation(s)
- Rebecca E McMahon
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
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Lupi A, Navarese EP, Lazzero M, Sansa M, Servi SD, Serra A, Bongo AS, Buffon A. Drug-Eluting Stents vs. Bare Metal Stents in Saphenous Vein Graft Disease - Insights From a Meta-Analysis of 7,090 Patients -. Circ J 2011; 75:280-9. [DOI: 10.1253/circj.cj-10-0186] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Eliano Pio Navarese
- Istituto di Cardiologia, Università Cattolica del Sacro Cuore
- Interventional Cardiology Unit, Hospital de la Santa Creu i Sant Pau
| | | | - Mara Sansa
- Cardiologia 2, Ospedale Maggiore della Carità
| | | | - Antonio Serra
- Interventional Cardiology Unit, Hospital de la Santa Creu i Sant Pau
| | | | - Antonio Buffon
- Istituto di Cardiologia, Università Cattolica del Sacro Cuore
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Nordgaard H, Swillens A, Nordhaug D, Kirkeby-Garstad I, Van Loo D, Vitale N, Segers P, Haaverstad R, Lovstakken L. Impact of competitive flow on wall shear stress in coronary surgery: computational fluid dynamics of a LIMA-LAD model. Cardiovasc Res 2010; 88:512-9. [PMID: 20581004 DOI: 10.1093/cvr/cvq210] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIMS Competitive flow from native coronary vessels is considered a major factor in the failure of coronary bypass grafts. However, the pathophysiological effects are not fully understood. Low and oscillatory wall shear stress (WSS) is known to induce endothelial dysfunction and vascular disease, like atherosclerosis and intimal hyperplasia. The aim was to investigate the impact of competitive flow on WSS in mammary artery bypass grafts. METHODS AND RESULTS Using computational fluid dynamics, WSS was calculated in a left internal mammary artery (LIMA) graft to the left anterior descending artery in a three-dimensional in vivo porcine coronary artery bypass graft model. The following conditions were investigated: high competitive flow (non-significant coronary lesion), partial competitive flow (significant coronary lesion), and no competitive flow (totally occluded coronary vessel). Time-averaged WSS of LIMA at high, partial, and no competitive flow were 0.3-0.6, 0.6-3.0, and 0.9-3.0 Pa, respectively. Further, oscillatory WSS quantified as the oscillatory shear index (OSI) ranged from (maximum OSI = 0.5 equals zero net WSS) 0.15 to 0.35, <0.05, and <0.05, respectively. Thus, high competitive flow resulted in substantial oscillatory and low WSS. Moderate competitive flow resulted in WSS and OSI similar to the no competitive flow condition. CONCLUSION Graft flow is highly dependent on the degree of competitive flow. High competitive flow was found to produce unfavourable WSS consistent with endothelial dysfunction and subsequent graft narrowing and failure. Partial competitive flow, however, may be better tolerated as it was found to be similar to the ideal condition of no competitive flow.
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Affiliation(s)
- Håvard Nordgaard
- Department of Circulation and Medical Imaging, The Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
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The resonance theory of coronary arterial wall stress as an explanation for the distribution of coronary artery disease. Med Hypotheses 2010; 74:820-2. [PMID: 20044212 DOI: 10.1016/j.mehy.2009.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 12/05/2009] [Indexed: 11/20/2022]
Abstract
The coronary arteries are unique within the arterial system in being subject to a continuous oscillatory displacement. It is hypothesised that oscillatory resonance of the coronary arteries occurs when the heart rate is the same as the arteries' Natural Frequency of oscillation. If resonance were to occur then standing waves would exist along the coronary arteries. The sites of the anti-nodes of such standing waves would be the sites of increased wall stress and therefore be expected to be predisposed to disease. Coronary artery resonance would explain the observed increased incidence of disease in the proximal segments of the arteries. It is proposed that coronary artery resonance is a previously unrecognised aetiological factor for coronary artery disease that contributes to its location. If the hypothesis is true then there are potential important consequences for the diagnosis and treatment of the disease.
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Goettsch C, Goettsch W, Arsov A, Hofbauer LC, Bornstein SR, Morawietz H. Long-term cyclic strain downregulates endothelial Nox4. Antioxid Redox Signal 2009; 11:2385-97. [PMID: 19309265 DOI: 10.1089/ars.2009.2561] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Endothelial cells in vivo are constantly exposed to mechanical forces such as cyclic strain. In endothelial cells, Nox4-containing NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (.O(2)(-)) formation. In this study, we analyzed the effect of cyclic strain on endothelial ROS formation by electron paramagnetic resonance spectroscopy, cytochrome c assay, and dihydroethidium fluorescence, on NO formation by Griess reaction and on gene expression by RT-PCR and Western blot. Primary cultures of human umbilical vein endothelial cells were exposed to 2-18% cyclic strain for up to 24 h using the Flexercell system. Long-term application of 5-12% cyclic strain downregulated Nox4 expression and ROS formation in a time-dependent manner. Downregulation of Nox4 was further confirmed by promoter analysis using dual-luciferase assay. Cu/Zn SOD, MnSOD, and catalase expression was decreased after application of chronic 12% cyclic strain. In contrast, endothelial NO formation and eNOS were increased by cyclic strain. Strain-dependent Nox4 downregulation was abolished by eNOS inhibition with L-NAME. In conclusion, physiological levels of cyclic strain downregulate Nox4 expression and superoxide anion formation. This novel mechanism might contribute to a vasoprotective balance between NO and superoxide anions in response to physiological mechanical stimulation of endothelial cells.
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Affiliation(s)
- Claudia Goettsch
- Division of Vascular Endothelium and Microcirculation, Department of Medicine III, University of Technology Dresden, D-01307 Dresden, Germany
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