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Karadeli HH, Kuram E. Single Component Polymers, Polymer Blends, and Polymer Composites for Interventional Endovascular Embolization of Intracranial Aneurysms. Macromol Biosci 2024; 24:e2300432. [PMID: 37992206 DOI: 10.1002/mabi.202300432] [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: 09/22/2023] [Revised: 11/03/2023] [Indexed: 11/24/2023]
Abstract
Intracranial aneurysm is the abnormal focal dilation in brain arteries. When untreated, it can enlarge to rupture points and account for subarachnoid hemorrhage cases. Intracranial aneurysms can be treated by blocking the flow of blood to the aneurysm sac with clipping of the aneurysm neck or endovascular embolization with embolics to promote the formation of the thrombus. Coils or an embolic device are inserted endovascularly into the aneurysm via a micro-catheter to fill the aneurysm. Many embolization materials have been developed. An embolization coil made of soft and thin platinum wire called the "Guglielmi detachable coil" (GDC) enables safer treatment for brain aneurysms. However, patients may experience aneurysm recurrence because of incomplete coil filling or compaction over time. Unsatisfactory recanalization rates and incomplete occlusion are the drawbacks of endovascular embolization. So, the fabrication of new medical devices with less invasive surgical techniques is mandatory to enhance the long-term therapeutic performance of existing endovascular procedures. For this aim, the current article reviews polymeric materials including blends and composites employed for embolization of intracranial aneurysms. Polymeric materials used in embolic agents, their advantages and challenges, results of the strategies used to overcome treatment, and results of clinical experiences are summarized and discussed.
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Affiliation(s)
- Hasan Hüseyin Karadeli
- Department of Neurology, Istanbul Medeniyet University Göztepe Prof. Dr. Süleyman Yalçın City Hospital, Istanbul, 34722, Turkey
| | - Emel Kuram
- Department of Mechanical Engineering, Gebze Technical University, Kocaeli, 41400, Turkey
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2
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Gonring DW, Zottola ZR, Hirad AA, Lakony R, Richards MS, Pitcher G, Stoner MC, Mix DS. Ultrasound elastography to quantify average percent pressure-normalized strain reduction associated with different aortic endografts in 3D-printed hydrogel phantoms. JVS Vasc Sci 2024; 5:100198. [PMID: 38846626 PMCID: PMC11153908 DOI: 10.1016/j.jvssci.2024.100198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 02/23/2024] [Indexed: 06/09/2024] Open
Abstract
Objective Strain has become a viable index for evaluating abdominal aortic aneurysm stability after endovascular aneurysm repair (EVAR). In addition, literature has shown that healthy aortic tissue requires a degree of strain to maintain homeostasis. This has led to the hypothesis that too much strain reduction conferred by a high degree of graft oversizing is detrimental to the aneurysm neck in the seal zone of abdominal aortic aneurysms after EVAR. We investigated this in a laboratory experiment by examining the effects that graft oversizing has on the pressure-normalized strain (ε ρ + ¯ /pulse pressure [PP]) reduction using four different infrarenal EVAR endografts and our ultrasound elastography technique. Approximate graft oversizing percentages were 20% (30 mm phantom-graft combinations), 30% (28 mm phantom-graft combinations), and 50% (24 mm phantom-graft combinations). Methods Axisymmetric, 10% by mass polyvinyl alcohol phantoms were connected to a flow simulator. Ultrasound elastography was performed before and after implantation with the four different endografts: (1) 36 mm polyester/stainless steel, (2) 36 mm polyester/electropolished nitinol, (3) 35 mm polytetrafluoroethylene (PTFE)/nitinol, and (4) 36 mm nitinol/polyester/platinum-iridium. Five ultrasound cine loops were taken of each phantom-graft combination. They were analyzed over two different cardiac cycles (end-diastole to end-diastole), yielding a total of 10 maximum mean principal strain (ε ρ + ¯ ) values.ε ρ + ¯ was divided by pulse pressure to yield pressure-normalized strain (ε ρ + ¯ /PP). An analysis of variance was performed for graft comparisons. We calculated the average percentε ρ + ¯ /PP reduction by manufacturer and percent oversizing. These values were used for linear regression analysis. Results Results from one-way analysis of variance showed a significant difference inε ρ + ¯ /PP between the empty phantom condition and all oversizing conditions for all graft manufacturers (F(3, 56) = 106.7 [graft A], 132.7 [graft B], 106.5 [graft C], 105.7 [graft D], P < .0001 for grafts A-D). There was a significant difference when comparing the 50% condition with the 30% and 20% conditions across all manufacturers by post hoc analysis (P < .0001). No significant difference was found when comparing the 20% and 30% oversizing conditions for any of the manufacturers or when comparingε ρ + ¯ /PP values across the manufacturers according to percent oversize. Linear regression demonstrated a significant positive correlation between the percent graft oversize and the all-graft average percentε ρ + ¯ /PP reduction (R 2 = 0.84, P < .0001). Conclusions This brief report suggests that a 10% increase in graft oversizing leads to an approximate 5.9% reduction inε ρ + ¯ /PP on average. Applied clinically, this increase may result in increased stiffness in axisymmetric vessels after EVAR. Further research is needed to determine if this is clinically significant.
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Affiliation(s)
- Dakota W. Gonring
- University of Rochester School of Medicine and Dentistry, Rochester, NY
| | | | - Adnan A. Hirad
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, NY
| | - Ronald Lakony
- Hajim School of Engineering and Applied Sciences, University of Rochester, Rochester, NY
| | - Michael S. Richards
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY
| | - Grayson Pitcher
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, NY
| | - Michael C. Stoner
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, NY
| | - Doran S. Mix
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, NY
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Rezaeitaleshmahalleh M, Sunderland KW, Lyu Z, Johnson T, King K, Liedl DA, Hofer JM, Wang M, Zhang X, Kuczmik W, Rasmussen TE, McBane RD, Jiang J. Computerized Differentiation of Growth Status for Abdominal Aortic Aneurysms: A Feasibility Study. J Cardiovasc Transl Res 2023; 16:874-885. [PMID: 36602668 DOI: 10.1007/s12265-022-10352-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/27/2022] [Indexed: 01/06/2023]
Abstract
Fast-growing abdominal aortic aneurysms (AAA) have a high rupture risk and poor outcomes if not promptly identified and treated. Our primary objective is to improve the differentiation of small AAAs' growth status (fast versus slow-growing) through a combination of patient health information, computational hemodynamics, geometric analysis, and artificial intelligence. 3D computed tomography angiography (CTA) data available for 70 patients diagnosed with AAAs with known growth status were used to conduct geometric and hemodynamic analyses. Differences among ten metrics (out of ninety metrics) were statistically significant discriminators between fast and slow-growing groups. Using a support vector machine (SVM) classifier, the area under receiving operating curve (AUROC) and total accuracy of our best predictive model for differentiation of AAAs' growth status were 0.86 and 77.50%, respectively. In summary, the proposed analytics has the potential to differentiate fast from slow-growing AAAs, helping guide resource allocation for the management of patients with AAAs.
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Affiliation(s)
- Mostafa Rezaeitaleshmahalleh
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA
| | - Kevin W Sunderland
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA
| | - Zonghan Lyu
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA
| | - Tonie Johnson
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA
| | - Kristin King
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA
| | - David A Liedl
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Janet M Hofer
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Min Wang
- Department of Management Science and Statistics, The University of Texas at San Antonio, San Antonio, TX, USA
| | - Xiaoming Zhang
- Department of Radiology, Mayo Clinic, MN, Rochester, USA
| | - Wiktoria Kuczmik
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Todd E Rasmussen
- Division of Vascular and Endovascular Surgery, Mayo Clinic, Rochester, MN, USA
| | - Robert D McBane
- Department of Cardiovascular Medicine, Mayo Clinic, MN, Rochester, USA
| | - Jingfeng Jiang
- Department of Biomedical Engineering, Michigan Technological University, MI, Houghton, USA.
- Joint Center for Biocomputing and Digital Health, Health Research Institute and Institute of Computing and Cybernetics, Michigan Technological University, Houghton, MI, USA.
- Department of Radiology, Mayo Clinic, MN, Rochester, USA.
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4
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Morris L, Tierney P, Hynes N, Sultan S. An in vitro Assessment of the Haemodynamic Features Occurring Within the True and False Lumens Separated by a Dissection Flap for a Patient-Specific Type B Aortic Dissection. Front Cardiovasc Med 2022; 9:797829. [PMID: 35369331 PMCID: PMC8968342 DOI: 10.3389/fcvm.2022.797829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/15/2022] [Indexed: 11/14/2022] Open
Abstract
One of the highest mortality rates of cardiovascular diseases is aortic dissections with challenging treatment options. Currently, less study has been conducted in developing in vitro patient-specific Type B aortic dissection models, which mimic physiological flow conditions along the true and false lumens separated by a dissection flap with multiple entry and exit tears. A patient-specific Stanford Type B aortic dissection scan was replicated by an in-house manufactured automatic injection moulding system and a novel modelling technique for creating the ascending aorta, aortic arch, and descending aorta incorporating arterial branching, the true/false lumens, and dissection flap with entry and exit intimal tears. The physiological flowrates and pressure values were monitored, which identified jet stream fluid flows entering and exiting the dissection tears. Pressure in the aorta’s true lumen region was controlled at 125/85 mmHg for systolic and diastolic values. Pressure values were obtained in eight sections along the false lumen using a pressure transducer. The true lumen systolic pressure varied from 122 to 128 mmHg along the length. Flow patterns were monitored by ultrasound along 12 sections. Detailed images obtained from the ultrasound transducer probe showed varied flow patterns with one or multiple jet steam vortices along the aorta model. The dissection flap movement was assessed at four sections of the patient-specific aorta model. The displacement values of the flap varied from 0.5 to 3 mm along the model. This model provides a unique insight into aortic dissection flow patterns and pressure distributions. This dissection phantom model can be used to assess various treatment options based on the surgical, endovascular, or hybrid techniques.
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Affiliation(s)
- Liam Morris
- Galway-Mayo Institute of Technology, Galway, Ireland
- Galway Medical Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Medical and Engineering Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Lero – Science Foundation Ireland Research Centre for Software, Galway-Mayo Institute of Technology, Galway, Ireland
- *Correspondence: Liam Morris,
| | - Paul Tierney
- Galway Medical Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Medical and Engineering Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
| | - Niamh Hynes
- CÚRAM, National University of Ireland, Galway, Ireland
| | - Sherif Sultan
- Western Vascular Institute, Department of Vascular and Endovascular Surgery, University College Hospital Galway, Galway, Ireland
- Department of Vascular and Endovascular Surgery, Galway Clinic, Royal College of Surgeons in Ireland, Doughiska, Ireland
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5
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Concannon J, Moerman KM, Hynes N, Sultan S, McGarry JP. Influence of shape-memory stent grafts on local aortic compliance. Biomech Model Mechanobiol 2021; 20:2373-2392. [PMID: 34541627 PMCID: PMC8595172 DOI: 10.1007/s10237-021-01514-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/18/2021] [Indexed: 12/19/2022]
Abstract
The effect of repair techniques on the biomechanics of the aorta is poorly understood, resulting in significant levels of postoperative complications for patients worldwide. This study presents a computational analysis of the influence of Nitinol-based devices on the biomechanical performance of a healthy patient-specific human aorta. Simulations reveal that Nitinol stent-grafts stretch the artery wall so that collagen is stretched to a straightened high-stiffness configuration. The high-compliance regime (HCR) associated with low diastolic lumen pressure is eliminated, and the artery operates in a low-compliance regime (LCR) throughout the entire cardiac cycle. The slope of the lumen pressure–area curve for the LCR post-implantation is almost identical to that of the native vessel during systole. This negligible change from the native LCR slope occurs because the stent-graft increases its diameter from the crimped configuration during deployment so that it reaches a low-stiffness unloading plateau. The effective radial stiffness of the implant along this unloading plateau is negligible compared to the stiffness of the artery wall. Provided the Nitinol device unloads sufficiently during deployment to the unloading plateau, the degree of oversizing has a negligible effect on the pressure–area response of the vessel, as each device exerts approximately the same radial force, the slope of which is negligible compared to the LCR slope of the native artery. We show that 10% oversizing based on the observed diastolic diameter in the mid descending thoracic aorta results in a complete loss of contact between the device and the wall during systole, which could lead to an endoleak and stent migration. 20% oversizing reaches the Dacron enforced area limit (DEAL) during the pulse pressure and results in an effective zero-compliance in the later portion of systole.
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Affiliation(s)
- J Concannon
- Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - K M Moerman
- Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - N Hynes
- Western Vascular Institute, National University of Ireland Galway, Galway, Ireland
| | - S Sultan
- Western Vascular Institute, National University of Ireland Galway, Galway, Ireland
| | - J P McGarry
- Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland.
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Mylonas SN, Moulakakis KG, Kadoglou N, Antonopoulos C, Kotsis TE, Kakisis J, Katsenis K, Liapis C. Arterial Stiffness Assessed by Cardio-Ankle Vascular Index in Patients With Abdominal Aortic Aneurysm and Its Alterations After Treatment. Vasc Endovascular Surg 2021; 55:804-810. [PMID: 34114528 DOI: 10.1177/15385744211023281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE The aim of the present study was to investigate a potential difference on the arterial stiffness among aneurysm patients and non-aneurysm controls, as well as to explore potential changes between patients treated either with endovascular or open repair. MATERIALS AND METHODS A 110 patients with an infrarenal AAA were prospectively enrolled in this study. Fifty-six patients received an EVAR, whereas 54 patients received an open surgical repair. Moreover, 103 gender and age-matched subjects without AAA served as controls. The cardio-ankle vascular index (CAVI) was applied for measurement of the arterial stiffness. RESULTS CAVI values were statistically higher in the AAA patients when compared with control subjects. Although at 48 hours postoperatively the CAVI values were increased in both groups when compared to baseline values, the difference in CAVI had a tendency to be higher in the open group compared to the endovascular group. At 6 months of follow up the CAVI values returned to the baseline for the patients of the open repair group. However, in the endovascular group CAVI values remained higher when compared with the baseline values. CONCLUSION Patients with AAAs demonstrated a higher value of CAVI compared to healthy controls. A significant increase of arterial stiffness in both groups during the immediate postoperative period was documented. The increase in arterial stiffness remained significant at 6 months in EVAR patients. Further studies are needed to elucidate the impact of a decreased aortic compliance after stentgraft implantation on the cardiac function of patients with AAA.
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Affiliation(s)
- Spyridon N Mylonas
- Department of Vascular and Endovascular Surgery, 61059University of Cologne, Cologne, Germany.,Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece
| | - Konstantinos G Moulakakis
- Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece.,Department of Vascular Surgery, Medical School, 484358University of Patras, Patras, Greece
| | - Nikolaos Kadoglou
- Department of Cardiology, Medical School, 371002University of Cyprus, Nicosia, Cyprus
| | | | - Thomas E Kotsis
- Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece
| | - John Kakisis
- Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece
| | - Konstantinos Katsenis
- Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece
| | - Christos Liapis
- Department of Vascular Surgery, Medical School, 68989University of Athens, Athens, Greece
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7
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Poupart O, Conti R, Schmocker A, Pancaldi L, Moser C, Nuss KM, Sakar MS, Dobrocky T, Grützmacher H, Mosimann PJ, Pioletti DP. Pulsatile Flow-Induced Fatigue-Resistant Photopolymerizable Hydrogels for the Treatment of Intracranial Aneurysms. Front Bioeng Biotechnol 2021; 8:619858. [PMID: 33553124 PMCID: PMC7855579 DOI: 10.3389/fbioe.2020.619858] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 12/22/2020] [Indexed: 11/13/2022] Open
Abstract
An alternative intracranial aneurysm embolic agent is emerging in the form of hydrogels due to their ability to be injected in liquid phase and solidify in situ. Hydrogels have the ability to fill an aneurysm sac more completely compared to solid implants such as those used in coil embolization. Recently, the feasibility to implement photopolymerizable poly(ethylene glycol) dimethacrylate (PEGDMA) hydrogels in vitro has been demonstrated for aneurysm application. Nonetheless, the physical and mechanical properties of such hydrogels require further characterization to evaluate their long-term integrity and stability to avoid implant compaction and aneurysm recurrence over time. To that end, molecular weight and polymer content of the hydrogels were tuned to match the elastic modulus and compliance of aneurysmal tissue while minimizing the swelling volume and pressure. The hydrogel precursor was injected and photopolymerized in an in vitro aneurysm model, designed by casting polydimethylsiloxane (PDMS) around 3D printed water-soluble sacrificial molds. The hydrogels were then exposed to a fatigue test under physiological pulsatile flow, inducing a combination of circumferential and shear stresses. The hydrogels withstood 5.5 million cycles and no significant weight loss of the implant was observed nor did the polymerized hydrogel protrude or migrate into the parent artery. Slight surface erosion defects of 2–10 μm in depth were observed after loading compared to 2 μm maximum for non-loaded hydrogels. These results show that our fine-tuned photopolymerized hydrogel is expected to withstand the physiological conditions of an in vivo implant study.
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Affiliation(s)
- Oriane Poupart
- Laboratory of Biomechanical Orthopedics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Riccardo Conti
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Andreas Schmocker
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland.,Laboratory of Applied Photonics Devices, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Lucio Pancaldi
- Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christophe Moser
- Laboratory of Applied Photonics Devices, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Katja M Nuss
- Musculoskeletal Research Unit, Department of Molecular Mechanisms of Disease, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Mahmut S Sakar
- Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Tomas Dobrocky
- Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Hansjörg Grützmacher
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Pascal J Mosimann
- Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, Bern, Switzerland.,Department of Diagnostic and Interventional Neuroradiology, Alfried Krupp Hospital, Essen, Germany
| | - Dominique P Pioletti
- Laboratory of Biomechanical Orthopedics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Elhelali A, Sultan S, Hynes N, Delassus P, Kavanagh EP, Fahy P, Stefanov F, Morris L. Evaluation of aortic arch aneurysms treated with the streamliner multilayer flow modulator. ITALIAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY 2020. [DOI: 10.23736/s1824-4777.20.01444-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Kyriakou F, Maclean C, Dempster W, Nash D. Efficiently Simulating an Endograft Deployment: A Methodology for Detailed CFD Analyses. Ann Biomed Eng 2020; 48:2449-2465. [PMID: 32394221 PMCID: PMC7505889 DOI: 10.1007/s10439-020-02519-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 04/24/2020] [Indexed: 01/10/2023]
Abstract
Numerical models of endografts for the simulation of endovascular aneurysm repair are increasingly important in the improvement of device designs and patient outcomes. Nevertheless, current finite element analysis (FEA) models of complete endograft devices come at a high computational cost, requiring days of runtime, therefore restricting their applicability. In the current study, an efficient FEA model of the Anaconda™ endograft (Terumo Aortic, UK) was developed, able to yield results in just over 4 h, an order of magnitude less than similar models found in the literature. The model was used to replicate a physical device that was deployed in a 3D printed aorta and comparison of the two shapes illustrated a less than 5 mm placement error of the model in the regions of interest, consistent with other more computationally intensive models in the literature. Furthermore, the final goal of the study was to utilize the deployed fabric model in a hemodynamic analysis that would incorporate realistic fabric folds, a feature that is almost always omitted in similar simulations. By successfully exporting the deployed graft geometry into a flow analysis, it was illustrated that the inclusion of fabric wrinkles enabled clinically significant flow patterns such as flow stagnation and recirculation to be detected, paving the way for this modelling methodology to be used in future for stent design optimisation.
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Affiliation(s)
- Faidon Kyriakou
- Department of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, Glasgow, G1 1XJ, UK.
| | | | - William Dempster
- Department of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, Glasgow, G1 1XJ, UK
| | - David Nash
- Department of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, Glasgow, G1 1XJ, UK
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10
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McHugo VS, Nolke L, Delassus P, MaCarthy E, McMahon CJ, Morris L. The impact of compliance on Stage 2 uni-ventricular heart circulation: An experimental assessment of the Bidirectional Glenn. Med Eng Phys 2020; 84:184-192. [PMID: 32977917 DOI: 10.1016/j.medengphy.2020.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 03/11/2020] [Accepted: 07/13/2020] [Indexed: 11/30/2022]
Abstract
The Bidirectional Glenn (BDG) or cavopulmonary connection is typically undertaken to volume unload the single ventricle in an effort to preserve ventricular and atrioventricular valve function. The geometry of this surgical palliation has been shown to influence the fluid energy loss as well as the distribution of flow that enters through the superior vena cava. In-vitro and in-silico studies to date have been performed on rigid wall models, while this investigation looks at the impact of flexible thin walled models versus rigid walls. Rigid and compliant models of two patient-specific Glenn geometries were fabricated and tested under various flow conditions, within a biosimulator capable of replicating patient specific flow conditions. It was found that the compliant models exhibit greater levels of energy loss compared to the rigid models. Along with these findings greater levels of turbulence was found in both compliant models compared to their rigid counterparts under ultrasound examinations. This shows that vessel compliance has a significant impact on the hemodynamics within hypoplastic left heart syndrome.
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Affiliation(s)
- V S McHugo
- Department of Mechanical and Industrial Engineering (GMIT), Galway Medical Technology Centre, Ireland.
| | - L Nolke
- Department of Pediatric Cardiology Our Lady's Children's Hospital Crumlin, Dublin, Ireland; University College Dublin School of Medicine, Belfield, Dublin, Ireland
| | - P Delassus
- Department of Mechanical and Industrial Engineering (GMIT), Galway Medical Technology Centre, Ireland
| | - E MaCarthy
- Department of Mechanical and Industrial Engineering (GMIT), Galway Medical Technology Centre, Ireland
| | - C J McMahon
- Department of Pediatric Cardiology Our Lady's Children's Hospital Crumlin, Dublin, Ireland; University College Dublin School of Medicine, Belfield, Dublin, Ireland.
| | - L Morris
- Department of Mechanical and Industrial Engineering (GMIT), Galway Medical Technology Centre, Ireland.
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11
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Domanin M, Piazzoli G, Trimarchi S, Vergara C. Image-Based Displacements Analysis and Computational Blood Dynamics after Endovascular Aneurysm Repair. Ann Vasc Surg 2020; 69:400-412. [PMID: 32738387 DOI: 10.1016/j.avsg.2020.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 01/14/2023]
Abstract
BACKGROUND To examine intraheartbeat displacements (IHD) and geometrical changes of endografts for abdominal aortic aneurysm repair over the course of years, defined as follow-up displacements (FUD), and to correlate them with computational fluid dynamics (CFD). Despite the widespread use of endovascular aneurysm repair (EVAR), we still know little about endograft behavior after deployment. METHODS Two cases, treated with either expanded polytetrafluoroethylene on a nitinol stent frame (PI) or with woven polyester fabric sutured to a stainless-steel Z stent skeleton (PII), were submitted to dynamic computed tomography angiography at 1, 12, and 60 months after implantation. After segmentation, IHD were computed as displacements of the reconstructed surface with respect to the diastolic instant. Similarly, FUD were studied using imaging techniques that align temporal successive segmentations. In addition, numerical simulations for blood dynamics were performed to compute viscous forces, specifically wall shear stress and time-averaged wall shear stress (TAWSS). RESULTS IHD analysis showed slight translations without deformation for the PI endograft with respect to the stiffer stainless-steel endograft behavior of PII. FUD showed in PI motion of the metallic struts mainly focused on the distal main body of the endograft and in the zone overlapping with iliac branches. In PII, we observed a huge FUD in the middle and inferior-anterior regions of the main body. CFD analysis revealed changes of velocity patterns associated with remodeling of the iliac zone for PI and of the main body region for PII, where flow impinges the lumen wall and progressively induces deformation of the endograft wires. Measurement of TAWSS demonstrated flow disturbances in the enlarged region correlated with displacement analysis. CONCLUSIONS Image-based displacement analysis associated with CFD enabled very subtle evaluations of endograft behavior on different temporal scales. This kind of study could be helpful both for physicians, forecasting evolution during the life span of the endograft, and manufacturers, giving them useful information about endograft implant performance and design.
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Affiliation(s)
- Maurizio Domanin
- Department of Clinical Sciences and Community Health, Università di Milano, Milan, Italy; Unità Operativa di Chirurgia Vascolare, Fondazione I.R.C.C.S. Cà Granda Ospedale Maggiore Policlinico di Milano, Milan, Italy.
| | - Giulia Piazzoli
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy
| | - Santi Trimarchi
- Department of Clinical Sciences and Community Health, Università di Milano, Milan, Italy; Unità Operativa di Chirurgia Vascolare, Fondazione I.R.C.C.S. Cà Granda Ospedale Maggiore Policlinico di Milano, Milan, Italy
| | - Christian Vergara
- LABS, Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Milan, Italy
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12
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Donadoni F, Bonfanti M, Pichardo-Almarza C, Homer-Vanniasinkam S, Dardik A, Díaz-Zuccarini V. An in silico study of the influence of vessel wall deformation on neointimal hyperplasia progression in peripheral bypass grafts. Med Eng Phys 2019; 74:137-145. [PMID: 31540730 DOI: 10.1016/j.medengphy.2019.09.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/08/2019] [Accepted: 09/08/2019] [Indexed: 10/26/2022]
Abstract
Neointimal hyperplasia (NIH) is a major obstacle to graft patency in the peripheral arteries. A complex interaction of biomechanical factors contribute to NIH development and progression, and although haemodynamic markers such as wall shear stress have been linked to the disease, these have so far been insufficient to fully capture its behaviour. Using a computational model linking computational fluid dynamics (CFD) simulations of blood flow with a biochemical model representing NIH growth mechanisms, we analyse the effect of compliance mismatch, due to the presence of surgical stitches and/or to the change in distensibility between artery and vein graft, on the haemodynamics in the lumen and, subsequently, on NIH progression. The model enabled to simulate NIH at proximal and distal anastomoses of three patient-specific end-to-side saphenous vein grafts under two compliance-mismatch configurations, and a rigid wall case for comparison, obtaining values of stenosis similar to those observed in the computed tomography (CT) scans. The maximum difference in time-averaged wall shear stress between the rigid and compliant models was 3.4 Pa, and differences in estimation of NIH progression were only observed in one patient. The impact of compliance on the haemodynamic-driven development of NIH was small in the patient-specific cases considered.
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Affiliation(s)
- Francesca Donadoni
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Mirko Bonfanti
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, W1W 7TS, UK
| | - Cesar Pichardo-Almarza
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Shervanthi Homer-Vanniasinkam
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK; Leeds Teaching Hospitals NHS Trust, LS1 3EX, UK; Division of Surgery, University of Warwick, Warwick, UK
| | - Alan Dardik
- The Department of Surgery, Yale University School of Medicine, New Haven, CT, USA; Veteran Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Vanessa Díaz-Zuccarini
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK; Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, W1W 7TS, UK.
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Salman HE, Ramazanli B, Yavuz MM, Yalcin HC. Biomechanical Investigation of Disturbed Hemodynamics-Induced Tissue Degeneration in Abdominal Aortic Aneurysms Using Computational and Experimental Techniques. Front Bioeng Biotechnol 2019; 7:111. [PMID: 31214581 PMCID: PMC6555197 DOI: 10.3389/fbioe.2019.00111] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 05/02/2019] [Indexed: 11/13/2022] Open
Abstract
Abdominal aortic aneurysm (AAA) is the dilatation of the aorta beyond 50% of the normal vessel diameter. It is reported that 4-8% of men and 0.5-1% of women above 50 years of age bear an AAA and it accounts for ~15,000 deaths per year in the United States alone. If left untreated, AAA might gradually expand until rupture; the most catastrophic complication of the aneurysmal disease that is accompanied by a striking overall mortality of 80%. The precise mechanisms leading to AAA rupture remains unclear. Therefore, characterization of disturbed hemodynamics within AAAs will help to understand the mechanobiological development of the condition which will contribute to novel therapies for the condition. Due to geometrical complexities, it is challenging to directly quantify disturbed flows for AAAs clinically. Two other approaches for this investigation are computational modeling and experimental flow measurement. In computational modeling, the problem is first defined mathematically, and the solution is approximated with numerical techniques to get characteristics of flow. In experimental flow measurement, once the setup providing physiological flow pattern in a phantom geometry is constructed, velocity measurement system such as particle image velocimetry (PIV) enables characterization of the flow. We witness increasing number of applications of these complimentary approaches for AAA investigations in recent years. In this paper, we outline the details of computational modeling procedures and experimental settings and summarize important findings from recent studies, which will help researchers for AAA investigations and rupture mechanics.
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Affiliation(s)
| | - Burcu Ramazanli
- Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey
| | - Mehmet Metin Yavuz
- Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey
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Raptis A, Xenos M, Kouvelos G, Giannoukas A, Matsagkas M. Haemodynamic performance of AFX and Nellix endografts: a computational fluid dynamics study. Interact Cardiovasc Thorac Surg 2019; 26:826-833. [PMID: 29325136 DOI: 10.1093/icvts/ivx414] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 12/03/2017] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES The objective of this study is to analyse the flow conditions in the AFX and Nellix endografts (EGs) accounting for their postimplantation configuration in patients with an endovascular aneurysm repair-treated abdominal aortic aneurysm. METHODS We reconstructed post-endovascular aneurysm repair computed tomography scans of patients treated with an AFX or Nellix EG creating post-implantation EG models. We examined 16 patients, 8 in each group. The blood flow properties were obtained by computational fluid dynamics simulations and were subsequently compared with physiological infrarenal blood flow properties measured in 5 healthy subjects. Specifically, pressure drop, maximum velocity and wall shear stress were measured at peak systole and mean helicity at mid-diastole. RESULTS Our statistical analyses showed that the haemodynamic properties in both control regions did not vary statistically after the implantation of either the AFX or the Nellix EG, except for helicity that was significantly lower in the abdominal part of the Nellix EG compared with the expected physiological measurement. Regardless of the overall blood flow restoration, it is important to note that low pressure drop was detected along the limbs of the AFX and suppressed blood helical motion was detected at the entrance of the Nellix device. CONCLUSIONS It is observed from the results that the AFX EG has achieved absolute restoration of blood flow after endovascular aneurysm repair, although the development of secondary flow in the upper part of the EG and the low pressure drop in its limbs should be acknowledged. The Nellix EG also seems to be haemodynamically efficient. However, the suppression of helical flow before blood enters the device might raise concerns about its clinical application.
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Affiliation(s)
- Anastasios Raptis
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina, Greece
| | - Michalis Xenos
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina, Greece.,Department of Mathematics, University of Ioannina, Ioannina, Greece
| | - George Kouvelos
- Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | - Athanasios Giannoukas
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina, Greece.,Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | - Miltiadis Matsagkas
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina, Greece.,Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa, Greece
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Numerical and Experimental Investigation of Novel Blended Bifurcated Stent Grafts with Taper to Improve Hemodynamic Performance. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2018; 2018:8054850. [PMID: 30271457 PMCID: PMC6151236 DOI: 10.1155/2018/8054850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/17/2018] [Accepted: 07/29/2018] [Indexed: 11/26/2022]
Abstract
The typical helical flow within the human arterial system is widely used when designing cardiovascular devices, as this helical flow can be generated using the “crossed limbs” strategy of the bifurcated stent graft (BSG) and enhanced by the tapered structure of arteries. Here, we propose the use of a deflected blended bifurcated stent graft (BBSG) with various tapers, using conventional blended BSGs with the same degree of taper as a comparison. Hemodynamic performances, including helical strength and wall shear stress- (WSS-) based indicators, were assessed. Displacement forces that may induce stent-graft migration were assessed using numerical simulations and in vitro experiments. The results showed that as the taper increased, the displacement force, helicity strength, and time-averaged wall shear stress (TAWSS) within the iliac grafts increased, whereas the oscillating shear index (OSI) and relative residence time (RRT) gradually decreased for both types of BBSGs. With identical tapers, deflected BBSGs, compared to conventional BBSGs, exhibited a wider helical structure and lower RRT on the iliac graft and lower displacement force; however, there were no differences in hemodynamic indicators. In summary, the presence of tapering facilitated helical flow and produced better hemodynamic performance but posed a higher risk of graft migration. Conventional and deflected BBSGs with taper might be the two optimal configurations for endovascular aneurysm repair, given the helical flow. The deflected BBSG provides a better configuration, compared to the conventional BBSG, when considering the reduction of migration risk.
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Gao J, Guo H, Tian S, Qiao Y, Han J, Li Y, Wang L. Preparation and mechanical performance of small-diameter PHBHHx vascular graft by electrospinning. INT J POLYM MATER PO 2018. [DOI: 10.1080/00914037.2018.1473865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Jing Gao
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Huiwen Guo
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Shunzhu Tian
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Yansha Qiao
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Jiarui Han
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Yuling Li
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
| | - Lu Wang
- Key Laboratory of Textile Science & Technology of Ministry of Education, College of Textiles, Donghua University, Shanghai, People’s Republic of China
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17
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Raptis A, Xenos M, Georgakarakos E, Kouvelos G, Giannoukas A, Matsagkas M. Hemodynamic Profile of Two Aortic Endografts Accounting for Their Postimplantation Position. J Med Device 2017. [DOI: 10.1115/1.4035687] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Endovascular aneurysm repair (EVAR) is a clinically effective technique for treating anatomically eligible abdominal aortic aneurysms (AAAs), involving the deployment of an endograft (EG) that is designed to prevent blood leakage in the aneurysmal sac. While most EGs have equivalent operating principles, the hemodynamic environment established by different EGs is not necessarily the same. So, to unveil the post-EVAR hemodynamic properties, we need an EG-specific computational approach that currently lacks from the literature. Endurant and Excluder are two EGs with similar pre-installation designs. We assumed that the flow conditions in the particular EGs do not vary significantly. The hypothesis was tested combining image reconstructions, computational fluid dynamics (CFD), and statistics, taking into account the postimplantation position of the EGs. Ten patients with Endurant EGs and ten patients with Excluder EGs were included in this study. The two groups were matched with respect to the preoperative morphological characteristics of the AAAs. The EG models are derived from image reconstructions of postoperative computed tomography scans. Wall shear stress (WSS), displacement force, velocity, and helicity were calculated in regions of interest within the EG structures, i.e., the main body, the upper and lower part of the limbs. Excluder generated higher WSS compared to Endurant, especially on the lower part of the limbs (p = 0.001). Spatial fluctuations of WSS were observed on the upper part of the Excluder limbs. Higher blood velocity was induced by Excluder in all the regions of interest (p = 0.04, p = 0.01, and p = 0.004). Focal points of secondary flow were detected in the main body of Endurant and the limbs of Excluder. The displacement force acting on the lower part of the Excluder limbs was stronger compared to the Endurant one (p = 0.03). The results showed that two similar EGs implanted in similar AAAs can induce significantly different flow properties. The delineation of the hemodynamic features associated with the various commercially available EGs could further promote the personalization of treatment offered to aneurysmal patients and inspire ideas for the improvement of EG designs in the future.
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Affiliation(s)
- Anastasios Raptis
- Cardiovascular Surgery Department, Sector of Surgery, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45500, Greece
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina 45500, Greece e-mails:
| | - Michalis Xenos
- Department of Mathematics, University of Ioannina, Ioannina 45500, Greece
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina 45500, Greece e-mail:
| | - Efstratios Georgakarakos
- Department of Vascular Surgery, “Democritus” Medical School, University Hospital of Alexandroupolis, Alexandroupolis 68100, Greece e-mail:
| | - George Kouvelos
- Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa 41334, Greece e-mail:
| | - Athanasios Giannoukas
- Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa 41334, Greece
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina 45500, Greece e-mail:
| | - Miltiadis Matsagkas
- Department of Vascular Surgery, Faculty of Medicine, University of Thessaly, Larissa 41334, Greece
- Laboratory for Vascular Simulations, Institute of Vascular Diseases, Ioannina 45500, Greece e-mails:
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18
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Stefanov F, McGloughlin T, Morris L. A computational assessment of the hemodynamic effects of crossed and non-crossed bifurcated stent-graft devices for the treatment of abdominal aortic aneurysms. Med Eng Phys 2016; 38:1458-1473. [PMID: 27773830 DOI: 10.1016/j.medengphy.2016.09.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 08/22/2016] [Accepted: 09/23/2016] [Indexed: 10/20/2022]
Abstract
There are several issues attributed with abdominal aortic aneurysm endovascular repair. The positioning of bifurcated stent-grafts (SG) may affect SG hemodynamics. The hemodynamics and geometrical parameters of crossing or non-crossing graft limbs have not being totally accessed. Eight patient-specific SG devices and four pre-operative cases were computationally simulated, assessing the hemodynamic and geometrical effects for crossed (n= 4) and non-crossed (n= 4) configurations. SGs eliminated the occurrence of significant recirculations within the sac prior treatment. Dean's number predicted secondary flow locations with the greatest recirculations occurring at the outlets especially during the deceleration phase. Peak drag force varied from 3.9 to 8.7N, with greatest contribution occurring along the axial and anterior/posterior directions. Average resultant drag force was 20% smaller for the crossed configurations. Maximum drag force orientation varied from 1.4° to 51°. Drag force angle varied from 1° to 5° during one cardiac cycle. 44% to 62% of the resultant force acted along the proximal centerline where SG migration is most likely to occur. The clinician's decision for SG positioning may be a critical parameter, and should be considered prior to surgery. All crossed SG devices had an increased spiral flow effect along the distal legs with reductions in drag forces.
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Affiliation(s)
- Florian Stefanov
- Galway Medical Technologies Centre, Department of Mechanical and Industrial Engineering, Galway Mayo Institute of Technology, Galway, Ireland
| | - Tim McGloughlin
- Department of Biomedical Engineering, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Liam Morris
- Galway Medical Technologies Centre, Department of Mechanical and Industrial Engineering, Galway Mayo Institute of Technology, Galway, Ireland.
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Raptis A, Xenos M, Georgakarakos E, Kouvelos G, Giannoukas A, Labropoulos N, Matsagkas M. Comparison of physiological and post-endovascular aneurysm repair infrarenal blood flow. Comput Methods Biomech Biomed Engin 2016; 20:242-249. [DOI: 10.1080/10255842.2016.1215437] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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20
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Guan Y, Wang L, Lin J, King MW. Compliance Study of Endovascular Stent Grafts Incorporated with Polyester and Polyurethane Graft Materials in both Stented and Unstented Zones. MATERIALS 2016; 9:ma9080658. [PMID: 28773781 PMCID: PMC5509269 DOI: 10.3390/ma9080658] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 11/16/2022]
Abstract
Compliance mismatch between stent graft and host artery may induce complications and blood flow disorders. However, few studies have been reported on stent graft compliance. This study aims to explore the deformation and compliance of stent graft in stented and unstented zones under three pressure ranges. Compliance of two stent grafts incorporated with polyurethane graft (nitinol-PU) and polyester graft (nitinol-PET) materials respectively were tested; the stents used in the two stent grafts were identical. For the circumferential deformation of the stent grafts under each pressure range, the nitinol-PET stent graft was uniform in both zones. The nitinol-PU stent graft was circumferentially uniform in the stented zone, however, it was nonuniform in the unstented zone. The compliance of the PU graft material was 15 times higher than that of the PET graft. No significant difference in compliance was observed between stented and unstented zones of the nitinol-PET stent graft regardless of the applied pressure range. However, for the nitinol-PU stent graft, compliance of the unstented PU region was approximately twice that of the stented region; thus, compliance along the length of the nitinol-PU stent graft was not constant and different from that of the nitinol-PET stent graft.
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Affiliation(s)
- Ying Guan
- Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620, China.
| | - Lu Wang
- Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620, China.
| | - Jing Lin
- Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620, China.
| | - Martin W King
- Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, 2999 North Renmin Road, Songjiang, Shanghai 201620, China.
- College of Textiles, North Carolina State University, Raleigh, NC 27695-8301, USA.
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Georgakarakos E, Ioannou CV, Georgiadis GS, Storck M, Trellopoulos G, Koutsias S, Lazarides MK. The ovation abdominal stent graft for the treatment of abdominal aortic aneurysms: current evidence and future perspectives. Expert Rev Med Devices 2016; 13:253-62. [DOI: 10.1586/17434440.2016.1147949] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Georgakarakos E, Argyriou C, Georgiadis GS, Lazarides MK. Non-Invasive Pulse Wave Analysis in a Thrombus-Free Abdominal Aortic Aneurysm after Implantation of a Nitinol Aortic Endograft. Front Surg 2016; 2:68. [PMID: 26793712 PMCID: PMC4707224 DOI: 10.3389/fsurg.2015.00068] [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] [Received: 10/12/2015] [Accepted: 12/17/2015] [Indexed: 11/13/2022] Open
Abstract
Endovascular aneurysm repair has been associated with changes in arterial stiffness, as estimated by pulse wave velocity (PWV). This marker is influenced by the medical status of the patient, the elastic characteristics of the aneurysm wall, and the presence of intraluminal thrombus. Therefore, in order to delineate the influence of the endograft implantation in the early post-operative period, we conducted non-invasively pulse wave analysis in a male patient with an abdominal aortic aneurysm containing no intraluminal thrombus, unremarkable past medical history, and absence of peripheral arterial disease. The estimated parameters were the systolic and diastolic pressure calculated at the aortic level (central pressures), PWV, augmentation pressure (AP) and augmentation index (AI), pressure wave reflection magnitude (RM), and peripheral resistance. Central systolic and diastolic pressure decreased post-operatively. PWV showed subtle changes from 11.6 to 10.6 and 10.9 m/s at 1-week and 1-month, respectively. Accordingly, the AI decreased from 28 to 14% and continued to drop to 25%. The AP decreased gradually from 15 to 6 and 4 mmHg. The wave RM dropped from 68 to 52% at 1-month. Finally, the peripheral resistance dropped from 1.41 to 0.99 and 0.85 dyn × s × cm−5. Our example shows that the implantation of an aortic endograft can modify the pressure wave reflection over the aortic bifurcation without causing significant alterations in PWV.
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Affiliation(s)
- Efstratios Georgakarakos
- Department of Vascular Surgery, University Hospital of Alexandroupolis, "Democritus" University of Thrace , Alexandroupolis , Greece
| | - Christos Argyriou
- Department of Vascular Surgery, University Hospital of Alexandroupolis, "Democritus" University of Thrace , Alexandroupolis , Greece
| | - George S Georgiadis
- Department of Vascular Surgery, University Hospital of Alexandroupolis, "Democritus" University of Thrace , Alexandroupolis , Greece
| | - Miltos K Lazarides
- Department of Vascular Surgery, University Hospital of Alexandroupolis, "Democritus" University of Thrace , Alexandroupolis , Greece
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An Experimental Evaluation of Device/Arterial Wall Compliance Mismatch for Four Stent-Graft Devices and a Multi-layer Flow Modulator Device for the Treatment of Abdominal Aortic Aneurysms. Eur J Vasc Endovasc Surg 2016; 51:44-55. [DOI: 10.1016/j.ejvs.2015.07.041] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 07/29/2015] [Indexed: 11/19/2022]
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Moore SS, O’Sullivan KJ, Verdecchia F. Shrinking the Supply Chain for Implantable Coronary Stent Devices. Ann Biomed Eng 2015; 44:497-507. [DOI: 10.1007/s10439-015-1471-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 09/24/2015] [Indexed: 12/13/2022]
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25
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Georgakarakos E, Ioannou CV, Trellopoulos G, Kontopodis N, Papachristodoulou A, Torsello G, Bisdas T. Immediate Change in Suprarenal Neck Angulation After Endovascular Aneurysm Repair. J Endovasc Ther 2015; 22:613-9. [DOI: 10.1177/1526602815591562] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Purpose: To compare the immediate suprarenal neck angulation change between the Ovation stent-graft, with its inflatable sealing rings, and a stent-graft with a conventional sealing mechanism. Methods: A case-control study was conducted in which 30 consecutive patients (mean age 67 years; all men) with abdominal aortic aneurysm (AAA) treated with the Ovation stent-graft (group O) were retrospectively compared with 24 patients (mean age 77 years; all men) contemporaneously treated with the Endurant stent-graft (group E) at 3 high-volume tertiary vascular centers. The variables recorded were the aortic neck length, preoperative and postoperative angulation, minimum and maximum diameters of the infrarenal neck, as well as the maximum AAA diameter. All patients had undergone preoperative and postoperative (within 30 days) computed tomographic angiography. Multiple regression analysis compared the relative contribution to neck angulation change of each geometric parameter and the type of endograft. Data are presented as the mean ± standard deviation. Results: The mean preoperative suprarenal neck angulation in group O was 23.2°±18.0° compared with 23.8°±22.9° in group E ( t test, p=0.91). The neck lengths were 29.2±14.6 and 23.2±11.0 mm in groups O and E, respectively (p=0.1). Similarly, the minimum and maximum neck diameters were 22.4±2.6 and 25±3.5 mm, respectively, in group O vs 23.3±3.6 mm and 27.0±5.7 mm, respectively, in group E (p=0.3 and 0.12, respectively). The maximum transverse diameters of the AAA in the 2 groups were comparable, that is, 57.0±9.0 mm in group O vs 53.2±11.1 mm in group E (p=0.17). The Ovation stent-graft caused greater decrease in the aortic neck angulation postoperatively compared with the Endurant device (13.2°±16.1° vs 6.1°±5.9°, p=0.04). Multiple regression analysis revealed that preoperative neck angulation (β coefficient 0.37, p<0.001) and the type of endograft (β coefficient −7.91, p=0.01) had significant influence on the postoperative neck angulation change. The intraclass correlation coefficient ranged from 0.951 to 0.990 for the preoperative measurements and from 0.911 to 0.999 for the postoperative measurements for each examiner or the total of estimates at the measurement time points. Conclusion: The Ovation stent-graft induces greater postoperative reduction in the AAA neck angulation compared to an endograft with stent-supported graft seal. Expanded research to infrarenal angle as well to greater angles and correlation to clinical events is justified.
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Affiliation(s)
- Efstratios Georgakarakos
- Department of Vascular Surgery, “Democritus” University of Thrace, University Hospital of Alexandroupolis, Greece
| | - Christos V. Ioannou
- Department of Vascular Surgery, University Hospital of Heraklion, University of Crete Medical School, Heraklion, Greece
| | - George Trellopoulos
- First Surgical Clinic, General Hospital “G. Papanikolaou” Exohi, Thessaloniki, Greece
| | - Nikolaos Kontopodis
- Department of Vascular Surgery, University Hospital of Heraklion, University of Crete Medical School, Heraklion, Greece
| | | | - Giovanni Torsello
- Department of Vascular Surgery, St. Franziskus Hospital, and University Clinic of Münster, Germany
| | - Theodosios Bisdas
- Department of Vascular Surgery, St. Franziskus Hospital, and University Clinic of Münster, Germany
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Moulakakis KG, Mylonas SN, Kakisis J, Kadoglou NPE, Papadakis I, Sfyroeras GS, Antonopoulos CCN, Mantas G, Ikonomidis I, Liapis CD. Arterial Stiffness Alterations and Inflammatory Response Following Endovascular Aortic Repair: Based on a Presentation at the 2013 VEITH Symposium, November 19-23, 2013 (New York, NY, USA). AORTA : OFFICIAL JOURNAL OF THE AORTIC INSTITUTE AT YALE-NEW HAVEN HOSPITAL 2015; 3:75-80. [PMID: 26798761 DOI: 10.12945/j.aorta.2015.14-071] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 03/27/2015] [Indexed: 11/18/2022]
Abstract
Endovascular abdominal aortic aneurysm repair (EVAR) and thoracic aortic aneurysm repair (TEVAR) have been widely incorporated into clinical practice. However, changes in arterial stiffness and post-implantation syndrome after aortic endografting remain important issues under investigation. The aneurysm sac wall motion after successful EVAR and TEVAR reflects complex interactions between all the components of the excluded aneurysm, including true compliance of the aneurysm wall itself, intra-aneurysm sac pressure, remodeling of the thrombus, and mechanical characteristics of the endograft. Experimental and clinical studies have shown that aortic endografting results in increased arterial stiffness in animal models. It can be assumed that the alterations of aortic mechanical properties can have a direct impact on heart output. The long-term impact of these mechanical changes on cardiovascular outcomes and the potential effects of different endografts on hemodynamics are important issues under investigation. Post-implantation syndrome (PIS) is a systemic inflammatory response frequently observed after endovascular treatment of aortic pathologies. The main features of PIS include fever, leukocytosis, elevated C-reactive protein levels, and coagulation disturbances. Endograft design appears to influence this inflammatory response following aortic endografting; woven polyester endografts have been shown to be associated with greater inflammatory response compared to PTFE stent grafts. The purpose of this paper is to review the literature to elucidate arterial stiffness alterations and inflammatory response after EVAR and TEVAR and the impact of endograft design on aortic stiffness and the post-inflammatory response.
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Affiliation(s)
| | - Spyridon N Mylonas
- Department of Vascular Surgery, Medical School, University of Athens, Greece
| | - John Kakisis
- Department of Vascular Surgery, Medical School, University of Athens, Greece
| | | | - Ioannis Papadakis
- Department of Cardiology, Attikon University Hospital, Athens, Greece
| | - George S Sfyroeras
- Department of Vascular Surgery, Medical School, University of Athens, Greece
| | | | - George Mantas
- Department of Vascular Surgery, Medical School, University of Athens, Greece
| | | | - Christos D Liapis
- Department of Vascular Surgery, Medical School, University of Athens, Greece
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An In Vitro Evaluation of Emboli Trajectories Within a Three-Dimensional Physical Model of the Circle of Willis Under Cerebral Blood Flow Conditions. Ann Biomed Eng 2015; 43:2265-78. [DOI: 10.1007/s10439-015-1250-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/09/2015] [Indexed: 10/24/2022]
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Zhang P, Sun A, Zhan F, Luan J, Deng X. Hemodynamic study of overlapping bare-metal stents intervention to aortic aneurysm. J Biomech 2014; 47:3524-30. [DOI: 10.1016/j.jbiomech.2014.08.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 06/16/2014] [Accepted: 08/22/2014] [Indexed: 11/25/2022]
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