1
|
Shiravand A, Richter K, Willmann P, Eulzer P, Lawonn K, Hundertmark A, Cattaneo G. Fabrication, characterization and numerical validation of a novel thin-wall hydrogel vessel model for cardiovascular research based on a patient-specific stenotic carotid artery bifurcation. Sci Rep 2024; 14:16301. [PMID: 39009618 PMCID: PMC11251049 DOI: 10.1038/s41598-024-66777-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 07/03/2024] [Indexed: 07/17/2024] Open
Abstract
In vitro vascular models, primarily made of silicone, have been utilized for decades for studying hemodynamics and supporting the development of implants for catheter-based treatments of diseases such as stenoses and aneurysms. Hydrogels have emerged as prominent materials in tissue-engineering applications, offering distinct advantages over silicone models for fabricating vascular models owing to their viscoelasticity, low friction, and tunable mechanical properties. Our study evaluated the feasibility of fabricating thin-wall, anatomical vessel models made of polyvinyl alcohol hydrogel (PVA-H) based on a patient-specific carotid artery bifurcation using a combination of 3D printing and molding technologies. The model's geometry, elastic modulus, volumetric compliance, and diameter distensibility were characterized experimentally and numerically simulated. Moreover, a comparison with silicone models with the same anatomy was performed. A PVA-H vessel model was integrated into a mock circulatory loop for a preliminary ultrasound-based assessment of fluid dynamics. The vascular model's geometry was successfully replicated, and the elastic moduli amounted to 0.31 ± 0.007 MPa and 0.29 ± 0.007 MPa for PVA-H and silicone, respectively. Both materials exhibited nearly identical volumetric compliance (0.346 and 0.342% mmHg-1), which was higher compared to numerical simulation (0.248 and 0.290% mmHg-1). The diameter distensibility ranged from 0.09 to 0.20% mmHg-1 in the experiments and between 0.10 and 0.18% mmHg-1 in the numerical model at different positions along the vessel model, highlighting the influence of vessel geometry on local deformation. In conclusion, our study presents a method and provides insights into the manufacturing and mechanical characterization of hydrogel-based thin-wall vessel models, potentially allowing for a combination of fluid dynamics and tissue engineering studies in future cardio- and neurovascular research.
Collapse
Affiliation(s)
- Ashkan Shiravand
- Institute of Biomedical Engineering, University of Stuttgart, Stuttgart, Germany.
| | - Kevin Richter
- Faculty of Natural and Environmental Sciences, University of Kaiserslautern-Landau, Landau, Germany
| | - Pia Willmann
- Institute of Biomedical Engineering, University of Stuttgart, Stuttgart, Germany
| | - Pepe Eulzer
- Faculty of Mathematics and Computer Science, University of Jena, Jena, Germany
| | - Kai Lawonn
- Faculty of Mathematics and Computer Science, University of Jena, Jena, Germany
| | - Anna Hundertmark
- Faculty of Natural and Environmental Sciences, University of Kaiserslautern-Landau, Landau, Germany
| | - Giorgio Cattaneo
- Institute of Biomedical Engineering, University of Stuttgart, Stuttgart, Germany
| |
Collapse
|
2
|
Kim JH, Chhai P, Rhee K. Development and characterization of viscoelastic polydimethylsiloxane phantoms for simulating arterial wall motion. Med Eng Phys 2021; 91:12-18. [PMID: 34074461 DOI: 10.1016/j.medengphy.2021.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 03/21/2021] [Accepted: 03/23/2021] [Indexed: 11/17/2022]
Abstract
Arterial wall viscoelasticity is likely to be a good diagnostic indicator of vascular disease, but only a few studies on the assessment of wall viscosity have been performed. Artery phantoms are manufactured using polydimethylsiloxane (PDMS) to simulate the viscoelastic characteristics of the artery wall, which depends on the wall tissue composition and progression of atherosclerosis. The viscoelastic property of PDMS is controlled by adjusting the mixture ratio of resin, curing agent, and pure silicone oil. The pressure and diameter waveforms of the artery phantom were measured to estimate the wall viscoelasticity. Elasticity is assessed using the diameter distention over the pulse pressure, and the viscosity is evaluated using the energy dissipation ratio of the pressure-diameter curve and the phase lag between the first harmonics of pressure and diameter waveforms (DP1). PDMS phantoms with resin-to-curing-agent ratios of 20:1 and 25:1 show viscoelastic characteristics similar to those of young and old human carotid arteries, respectively. Adding pure silicone oil further softens the silicone elastomer while decreasing its viscosity. The phantoms with 10:1:5 and 10:1:8 mixture ratios (resin: curing agent: silicone oil) show elasticity similar to that of the 20:1:0 and 25:1:0 ratios, respectively, albeit with a noticeable decrease in viscosity. An abrupt decrease in the phase lag (DP1) was found near the interface of the arterial phantom with different mixture ratios (20:1:0 and 10:1:5), while the change in diameter distension was negligible. DP1 may be a new index to differentiate wall tissues with similar elastic properties but different viscous behavior. The pressure diameter curve and DP1 of the phantom simulating the atherosclerosis wall can be compared with patient data and applied to clinical evaluation of plaque viscoelasticity. Computational analysis of arterial wall motion was performed using a standard linear viscoelastic model. The model parameters were determined from the measured pressure-diameter relationship, and the arterial wall motions of phantoms with different viscoelastic properties were successfully simulated. The computational model may provide a useful insight into the changes of arterial viscoelasticity caused by pathogenic wall degeneration.
Collapse
Affiliation(s)
- Je Hyun Kim
- Department of Mechanical Engineering, Myongji University, 116 Myongji-ro, Cheoin-gu, Yongin-si, Gyeonggi-do 17058, South Korea
| | - Pengsrorn Chhai
- Department of Mechanical Engineering, Myongji University, 116 Myongji-ro, Cheoin-gu, Yongin-si, Gyeonggi-do 17058, South Korea
| | - Kyehan Rhee
- Department of Mechanical Engineering, Myongji University, 116 Myongji-ro, Cheoin-gu, Yongin-si, Gyeonggi-do 17058, South Korea.
| |
Collapse
|
3
|
Greenwood TE, Hatch SE, Colton MB, Thomson SL. 3D Printing Low-Stiffness Silicone Within a Curable Support Matrix. ADDITIVE MANUFACTURING 2021; 37:101681. [PMID: 33718006 PMCID: PMC7946128 DOI: 10.1016/j.addma.2020.101681] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Embedded 3D printing processes involve extruding ink within a support matrix that supports the ink throughout printing and curing. In once class of embedded 3D printing, which we refer to as "removable embedded 3D printing," curable inks are printed, cured, then removed from the uncured support matrix. Removable embedded 3D printing is advantageous because low-viscosity inks can be patterned in freeform geometries which may not be feasible to create via casting and other printing processes. When printing solid-infill geometries, however, uncured support matrix becomes trapped within the prints, which may be undesirable. This study builds on previous work by formulating a support matrix for removable embedded 3D printing that cures when mixed with the printed silicone ink to solve the problem of trapped, uncured support matrix within solid-infill prints. Printed specimens are shown to have a nearly isotropic elastic modulus in directions perpendicular and parallel to the printed layers, and a decreased modulus and increased elongation at break compared to specimens cast from the ink. The rheological properties of the support matrix are reported. The capabilities of the printer and support matrix are demonstrated by printing a variety of geometries from four UV and addition-cure silicone inks. Shapes printed with these inks range by nearly two orders of magnitude in stiffness and have failure strains between approximately 50 and 250%, suggesting a wide range of potential applications for this printing process.
Collapse
Affiliation(s)
- Taylor E Greenwood
- Department of Mechanical Engineering, Brigham Young University, Provo, UT, 84602, USA
| | - Serah E Hatch
- Department of Mechanical Engineering, Brigham Young University, Provo, UT, 84602, USA
| | - Mark B Colton
- Department of Mechanical Engineering, Brigham Young University, Provo, UT, 84602, USA
| | - Scott L Thomson
- Department of Mechanical Engineering, Brigham Young University, Provo, UT, 84602, USA
| |
Collapse
|
4
|
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: 42] [Impact Index Per Article: 8.4] [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.
Collapse
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
| | | |
Collapse
|
5
|
Chen T, Lancaster M, Lin DSY, Doyle MG, Forbes TL, Amon CH. Measurement of Frictional Properties of Aortic Stent Grafts and Their Delivery Systems. J Med Device 2019. [DOI: 10.1115/1.4043292] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Stent grafts are medical devices used to treat abdominal aortic aneurysms (AAAs) in endovascular aneurysm repair (EVAR). Computational and experimental models have been developed to study stent graft delivery and deployment during EVAR; however, frictional properties have not been taken into account in most previous studies. The objective of this study was to determine the coefficients of friction of three commercially available stent grafts (Cook Zenith, Medtronic Endurant, and Vascutek Anaconda), their delivery sheaths, a porcine aorta, and two mock arterial materials. Stent grafts were obtained and separated into stents, graft fabric, and sheaths. Using a custom-made friction measurement apparatus, the coefficients of friction were measured between five material pairs: (i) the stents and inner surface of the sheath, (ii) the graft fabric and inner surface of the sheath, (iii) the outer surface of the sheath and a porcine aorta, (iv) the outer surface of the sheath and three different polyvinyl alcohol (PVA) cryogels, and (v) the outer surface of the sheath and a polydimethylsiloxane (PDMS) sheet. The results show that the coefficients of friction between the graft fabric and the sheath were higher than those between the stents and the sheath. The PVA cryogels showed more comparable frictional properties to the porcine aorta than did the PDMS sheet, suggesting that PVA cryogels provide a more accurate approximation for the in vivo frictional properties. These results can be used to improve the accuracy of computational models for stent graft delivery and deployment and to select appropriate materials for vascular phantoms.
Collapse
Affiliation(s)
- Tianhao Chen
- Division of Engineering Science, University of Toronto, 35 Street George Street, Toronto, ON M5S 1A4, Canada e-mail:
| | - Michael Lancaster
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada e-mail:
| | - Dawn S. Y. Lin
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada e-mail:
| | - Matthew G. Doyle
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network, University of Toronto, 200 Elizabeth Street, Eaton North 6-222, Toronto, ON M5G 2C4, Canada e-mail:
| | - Thomas L. Forbes
- Division of Vascular Surgery, Peter Munk Cardiac Centre, University Health Network, University of Toronto, 200 Elizabeth Street, Eaton North 6-222, Toronto, ON M5G 2C4, Canada e-mail:
| | - Cristina H. Amon
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Rosebrugh Building, 164 College Street, Toronto, ON M5S3G9, Canada e-mail:
| |
Collapse
|
6
|
Mix DS, Yang L, Johnson CC, Couper N, Zarras B, Arabadjis I, Trakimas LE, Stoner MC, Day SW, Richards MS. Detecting Regional Stiffness Changes in Aortic Aneurysmal Geometries Using Pressure-Normalized Strain. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2372-2394. [PMID: 28728780 PMCID: PMC5562537 DOI: 10.1016/j.ultrasmedbio.2017.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 04/26/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Transabdominal ultrasound elasticity imaging could improve the assessment of rupture risk for abdominal aortic aneurysms by providing information on the mechanical properties and stress or strain states of vessel walls. We implemented a non-rigid image registration method to visualize the pressure-normalized strain within vascular tissues and adapted it to measure total strain over an entire cardiac cycle. We validated the algorithm's performance with both simulated ultrasound images with known principal strains and anatomically accurate heterogeneous polyvinyl alcohol cryogel vessel phantoms. Patient images of abdominal aortic aneurysm were also used to illustrate the clinical feasibility of our imaging algorithm and the potential value of pressure-normalized strain as a clinical metric. Our results indicated that pressure-normalized strain could be used to identify spatial variations in vessel tissue stiffness. The results of this investigation were sufficiently encouraging to warrant a clinical study measuring abdominal aortic pressure-normalized strain in a patient population with aneurysmal disease.
Collapse
Affiliation(s)
- Doran S Mix
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA.
| | - Ling Yang
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Camille C Johnson
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Nathan Couper
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Ben Zarras
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Isaac Arabadjis
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Lauren E Trakimas
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Michael C Stoner
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Steven W Day
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Michael S Richards
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| |
Collapse
|
7
|
Campeau MA, Lortie A, Tremblay P, Béliveau MO, Dubé D, Langelier È, Rouleau L. Effect of manufacturing and experimental conditions on the mechanical and surface properties of silicone elastomer scaffolds used in endothelial mechanobiological studies. Biomed Eng Online 2017; 16:90. [PMID: 28705250 PMCID: PMC5513328 DOI: 10.1186/s12938-017-0380-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/06/2017] [Indexed: 11/17/2022] Open
Abstract
Background Mechanobiological studies allow the characterization of cell response to mechanical stresses. Cells need to be supported by a material with properties similar to the physiological environment. Silicone elastomers have been used to produce various in vitro scaffolds of different geometries for endothelial cell studies given its relevant mechanical, optical and surface properties. However, obtaining defined and repeatable properties is a challenge as depending on the different manufacturing and processing steps, mechanical and surface properties may vary significantly between research groups. Methods The impact of different manufacturing and processing methods on the mechanical and surface properties was assessed by measuring the Young’s modulus and the contact angle. Silicone samples were produced using different curing temperatures and processed with different sterilization techniques and hydrophilization conditions. Results Different curing temperatures were used to obtain materials of different stiffness with a chosen silicone elastomer, i.e. Sylgard 184®. Sterilization by boiling had a tendency to stiffen samples cured at lower temperatures whereas UV and ethanol did not alter the material properties. Hydrophilization using sulphuric acid allowed to decrease surface hydrophobicity, however this effect was lost over time as hydrophobic recovery occurred. Extended contact with water maintained decreased hydrophobicity up to 7 days. Mechanobiological studies require complete cell coverage of the scaffolds used prior to mechanical stresses exposure. Different concentrations of fibronectin and collagen were used to coat the scaffolds and cell seeding density was varied to optimize cell coverage. Conclusion This study highlights the potential bias introduced by manufacturing and processing conditions needed in the preparation of scaffolds used in mechanobiological studies involving endothelial cells. As manufacturing, processing and cell culture conditions are known to influence cell adhesion and function, they should be more thoroughly assessed by research groups that perform such mechanobiological studies using silicone. Electronic supplementary material The online version of this article (doi:10.1186/s12938-017-0380-5) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Marc-Antoine Campeau
- Department of Chemical Engineering, McGill University, Montreal, QC, H3A 0C5, Canada
| | - Audrey Lortie
- Département de génie chimique et biotechnologique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Pierrick Tremblay
- Département de génie chimique et biotechnologique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Marc-Olivier Béliveau
- Département de génie chimique et biotechnologique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Dominic Dubé
- Département de génie mécanique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Ève Langelier
- Département de génie mécanique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada.,Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - Léonie Rouleau
- Département de génie mécanique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada. .,Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada.
| |
Collapse
|
8
|
Botar CC, Tóth ÁÁ, Klisurić OR, Nićiforović DD, Vučaj Ćirilović VA, Till VE. Dynamic simulation and Doppler Ultrasonography validation of blood flow behavior in Abdominal Aortic Aneurysm. Phys Med 2017; 37:1-8. [DOI: 10.1016/j.ejmp.2017.03.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 03/20/2017] [Accepted: 03/27/2017] [Indexed: 10/19/2022] Open
|
9
|
Ruiz de Galarreta S, Cazón A, Antón R, Finol EA. A Methodology for Verifying Abdominal Aortic Aneurysm Wall Stress. J Biomech Eng 2017; 139:2554137. [PMID: 27636678 DOI: 10.1115/1.4034710] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 11/08/2022]
Abstract
An abdominal aortic aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from the numerical studies against the experimental testing. To this end, four AAA phantoms were manufactured using vacuum casting. The geometry of each phantom was subject to microcomputed tomography (μCT) scanning at zero and three other intraluminal pressures: 80, 100, and 120 mm Hg. A zero-pressure geometry algorithm was used to calculate the wall stress in the phantom, while the numerical wall stress was calculated with a finite-element analysis (FEA) solver based on the actual zero-pressure geometry subjected to 80, 100, and 120 mm Hg intraluminal pressure loading. Results demonstrate the moderate accuracy of this methodology with small relative differences in the average wall stress (1.14%). Additionally, the contribution of geometric factors to the wall stress distribution was statistically analyzed for the four phantoms. The results showed a significant correlation between wall thickness and mean curvature (MC) with wall stress.
Collapse
Affiliation(s)
- Sergio Ruiz de Galarreta
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Aitor Cazón
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Raúl Antón
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Ender A Finol
- Department of Biomedical Engineering, The University of Texas at San Antonio, One UTSA Circle, AET 1.360, San Antonio, TX 78249-0669 e-mail:
| |
Collapse
|
10
|
Anisotropic abdominal aortic aneurysm replicas with biaxial material characterization. Med Eng Phys 2016; 38:1505-1512. [DOI: 10.1016/j.medengphy.2016.09.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 08/16/2016] [Accepted: 09/23/2016] [Indexed: 11/19/2022]
|
11
|
Hollis L, Conlisk N, Thomas-Seale LEJ, Roberts N, Pankaj P, Hoskins PR. Computational simulations of MR elastography in idealised abdominal aortic aneurysms. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/4/045016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
12
|
Courtial EJ, Fanton L, Orkisz M, Douek P, Huet L, Fulchiron R. Hyper-Viscoelastic Behavior of Healthy Abdominal Aorta. Ing Rech Biomed 2016. [DOI: 10.1016/j.irbm.2016.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
13
|
Ribeiro de Oliveira MM, Nicolato A, Santos M, Godinho JV, Brito R, Alvarenga A, Martins ALV, Prosdocimi A, Trivelato FP, Sabbagh AJ, Reis AB, Maestro RD. Face, content, and construct validity of human placenta as a haptic training tool in neurointerventional surgery. J Neurosurg 2016; 124:1238-44. [DOI: 10.3171/2015.1.jns141583] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECT
The development of neurointerventional treatments of central nervous system disorders has resulted in the need for adequate training environments for novice interventionalists. Virtual simulators offer anatomical definition but lack adequate tactile feedback. Animal models, which provide more lifelike training, require an appropriate infrastructure base. The authors describe a training model for neurointerventional procedures using the human placenta (HP), which affords haptic training with significantly fewer resource requirements, and discuss its validation.
METHODS
Twelve HPs were prepared for simulated endovascular procedures. Training exercises performed by interventional neuroradiologists and novice fellows were placental angiography, stent placement, aneurysm coiling, and intravascular liquid embolic agent injection.
RESULTS
The endovascular training exercises proposed can be easily reproduced in the HP. Face, content, and construct validity were assessed by 6 neurointerventional radiologists and 6 novice fellows in interventional radiology.
CONCLUSIONS
The use of HP provides an inexpensive training model for the training of neurointerventionalists. Preliminary validation results show that this simulation model has face and content validity and has demonstrated construct validity for the interventions assessed in this study.
Collapse
Affiliation(s)
- Marcelo Magaldi Ribeiro de Oliveira
- 1Department of Surgery, Federal University of Minas Gerais, Brazil
- 2Department of Neurosurgery, Neurosurgical Simulation Research and Training Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec
- 3Surgical Simulation Centre, Mount Sinai Hospital, University of Toronto, Ontario, Canada; and
| | - Arthur Nicolato
- 1Department of Surgery, Federal University of Minas Gerais, Brazil
| | - Marcilea Santos
- 1Department of Surgery, Federal University of Minas Gerais, Brazil
| | | | - Rafael Brito
- 1Department of Surgery, Federal University of Minas Gerais, Brazil
| | | | | | - André Prosdocimi
- 1Department of Surgery, Federal University of Minas Gerais, Brazil
| | | | - Abdulrahman J. Sabbagh
- 4Department of Neurosurgery, National Neurosciences Institute, King Fahad Medical City, Riyadh, Saudi Arabia
| | | | - Rolando Del Maestro
- 2Department of Neurosurgery, Neurosurgical Simulation Research and Training Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec
| |
Collapse
|
14
|
In vitro biomechanical evaluation of single impulse and repetitive mechanical shockwave devices utilized for spinal manipulative therapy. Ann Biomed Eng 2014; 42:2524-36. [PMID: 25326437 DOI: 10.1007/s10439-014-1115-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 09/06/2014] [Indexed: 01/07/2023]
Abstract
Mechanical shockwave therapy devices have been in clinical use for almost 40 years. While most often used to treat back pain, our understanding of their biomechanical performance is very limited. From biomechanical studies we know that biological tissue is viscoelastic and preferably excited around its resonance frequency. Targeting these frequencies has been the focus in extracorporeal shock wave lithotripsy, but these concepts are relatively new in orthopedic and rehabilitation therapies. The exact mechanism by which shockwave therapy acts is not known. Knowledge of the performance characteristics of these devices, correlated with clinical outcome studies, may lead to better patient selection, improvement of device functionality, and knowledge of the underlying working principals of therapy. The objectives of this study were to determine the ability of several commercial shockwave devices to achieve a desired thrust profile in a benchtop setting, determine the thrust profile in a clinical analog, and determine the influence of operator experience level on device performance. We conducted two different types of testing: (1) bench testing to evaluate the devices themselves, and (2) clinical equivalent testing to determine the influence of the operator. The results indicated a significant dependence of thrust output on the compliance of the test media. The Activator V-E device matched the ideal half-sine thrust profile to 94%, followed by the Impulse device (84%), the Activator IV/FS (74%), and the Activator II (48%). While most devices deviated from the ideal profile on the return path, the Impulse device exhibited a secondary peak. Moreover, the Activator V-E device provided evidence that the device performs consistently despite operator experience level. This has been a major concern in manual spinal manipulation. Based on our results, a hyper-flexible spine would receive a lower peak thrust force than a hypo-flexible spine at the same power setting. Furthermore, a hand-held operation further reduced the peak thrust force as it increased the system compliance. However, that influence was dissimilar for the different devices. Although controlled clinical trials are needed to determine the correlation between thrust profile and clinical outcome, already ongoing clinical studies indicate an improved patient satisfaction due to reduced treatment pain when devices are used with a thrust characteristic closer to an ideal sine wave.
Collapse
|
15
|
In-plane mechanics of soft architectured fibre-reinforced silicone rubber membranes. J Mech Behav Biomed Mater 2014; 40:339-353. [PMID: 25265032 DOI: 10.1016/j.jmbbm.2014.09.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/01/2014] [Accepted: 09/08/2014] [Indexed: 11/22/2022]
Abstract
Silicone rubber membranes reinforced with architectured fibre networks were processed with a dedicated apparatus, allowing a control of the fibre content and orientation. The membranes were subjected to tensile loadings combined with continuous and discrete kinematical field measurements (DIC and particle tracking). These tests show that the mechanical behaviour of the membranes is hyperelastic at the first order. They highlight the influence of the fibre content and orientation on both the membrane in-plane deformation and stress levels. They also prove that for the considered fibrous architectures and mechanical loadings, the motion and deformation of fibres is an affine function of the macroscale transformation. These trends are fairly well described by the micromechanical model proposed recently in Bailly et al. (JMBBM, 2012). This result proves that these materials are very good candidates for new biomimetic membranes, e.g. to improve aortic analogues used for in vitro experiments, or existing textiles used for vascular (endo)prostheses.
Collapse
|
16
|
Bailly L, Deplano V, Lemercier A, Boiron O, Meyer C. New experimental protocols for tensile testing of abdominal aortic analogues. Med Eng Phys 2014; 36:800-4. [DOI: 10.1016/j.medengphy.2014.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 12/17/2013] [Accepted: 02/06/2014] [Indexed: 11/28/2022]
|
17
|
O׳Leary SA, Kavanagh EG, Grace PA, McGloughlin TM, Doyle BJ. The biaxial mechanical behaviour of abdominal aortic aneurysm intraluminal thrombus: Classification of morphology and the determination of layer and region specific properties. J Biomech 2014; 47:1430-7. [DOI: 10.1016/j.jbiomech.2014.01.041] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 12/29/2013] [Accepted: 01/18/2014] [Indexed: 10/25/2022]
|
18
|
Haworth KJ, Weidner CR, Abruzzo TA, Shearn JT, Holland CK. Mechanical properties and fibrin characteristics of endovascular coil-clot complexes: relevance to endovascular cerebral aneurysm repair paradigms. J Neurointerv Surg 2014; 7:291-6. [PMID: 24668257 DOI: 10.1136/neurintsurg-2013-011076] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Although coil embolization is known to prevent rebleeding from acutely ruptured cerebral aneurysms, the underlying biological and mechanical mechanisms have not been characterized. We sought to determine if microcoil-dependent interactions with thrombus induce structural and mechanical changes in the adjacent fibrin network. Such changes could play an important role in the prevention of aneurysm rebleeding. METHODS The stiffness of in vitro human blood clots and coil-clot complexes implanted into aneurysm phantoms were measured immediately after formation and after retraction for 3 days using unconfined uniaxial compression assays. Scanning electron microscopy of the coil-clot complexes showed the effect of coiling on clot structure. RESULTS The coil packing densities achieved were in the range of clinical practice. Bare platinum coils increased clot stiffness relative to clot alone (Young's modulus 6.9 kPa and 0.83 kPa, respectively) but did not affect fibrin structure. Hydrogel-coated coils prevented formation of a clot and had no significant effect on clot stiffness (Young's modulus 2 kPa) relative to clot alone. Clot age decreased fiber density by 0.2 fibers/µm(2) but not the stiffness of the bare platinum coil-clot complex. CONCLUSIONS The stiffness of coil-clot complexes is related to the summative stiffness of the fibrin network and associated microcoils. Hydrogel-coated coils exhibit significantly less stiffness due to the mechanical properties of the hydrogel and the inhibition of fibrin network formation by the hydrogel. These findings have important implications for the design and engineering of aneurysm occlusion devices.
Collapse
Affiliation(s)
- Kevin J Haworth
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA Biomedical Engineering Program, University of Cincinnati, Cincinnati, Ohio, USA
| | | | - Todd A Abruzzo
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA Department of Neurosurgery, University of Cincinnati, Cincinnati, Ohio, USA
| | - Jason T Shearn
- Biomedical Engineering Program, University of Cincinnati, Cincinnati, Ohio, USA
| | - Christy K Holland
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA Biomedical Engineering Program, University of Cincinnati, Cincinnati, Ohio, USA
| |
Collapse
|
19
|
Cloonan AJ, Shahmirzadi D, Li RX, Doyle BJ, Konofagou EE, McGloughlin TM. 3D-Printed Tissue-Mimicking Phantoms for Medical Imaging and Computational Validation Applications. 3D PRINTING AND ADDITIVE MANUFACTURING 2014; 1:14-23. [PMID: 28804733 PMCID: PMC4981152 DOI: 10.1089/3dp.2013.0010] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Abdominal aortic aneurysm (AAA) is a permanent, irreversible dilation of the distal region of the aorta. Recent efforts have focused on improved AAA screening and biomechanics-based failure prediction. Idealized and patient-specific AAA phantoms are often employed to validate numerical models and imaging modalities. To produce such phantoms, the investment casting process is frequently used, reconstructing the 3D vessel geometry from computed tomography patient scans. In this study the alternative use of 3D printing to produce phantoms is investigated. The mechanical properties of flexible 3D-printed materials are benchmarked against proven elastomers. We demonstrate the utility of this process with particular application to the emerging imaging modality of ultrasound-based pulse wave imaging, a noninvasive diagnostic methodology being developed to obtain regional vascular wall stiffness properties, differentiating normal and pathologic tissue in vivo. Phantom wall displacements under pulsatile loading conditions were observed, showing good correlation to fluid-structure interaction simulations and regions of peak wall stress predicted by finite element analysis. 3D-printed phantoms show a strong potential to improve medical imaging and computational analysis, potentially helping bridge the gap between experimental and clinical diagnostic tools.
Collapse
Affiliation(s)
- Aidan J. Cloonan
- Centre for Applied Biomedical Engineering Research, Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
- Irish Centre for Composites Research, Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
- Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
| | - Danial Shahmirzadi
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - Ronny X. Li
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York
| | - Barry J. Doyle
- Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, University of Western Australia, Perth, Australia
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom
| | - Elisa E. Konofagou
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, New York
- Department of Radiology, Columbia University, New York, New York
| | - Tim M. McGloughlin
- Centre for Applied Biomedical Engineering Research, Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
- Materials and Surface Science Institute, University of Limerick, Limerick, Ireland
- Department of Biomedical Engineering, Khalifa University of Science, Technology & Research, Abu Dhabi, United Arab Emirates
| |
Collapse
|
20
|
Allard L, Soulez G, Chayer B, Qin Z, Roy D, Cloutier G. A multimodality vascular imaging phantom of an abdominal aortic aneurysm with a visible thrombus. Med Phys 2014; 40:063701. [PMID: 23718616 DOI: 10.1118/1.4803497] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE With the continuous development of new stent grafts and implantation techniques, it has now become technically feasible to treat abdominal aortic aneurysms (AAA) with challenging anatomy using endovascular repair with standard, fenestrated, or branched stent-grafts. In vitro experimentations are very useful to improve stent-graft design and conformability or imaging guidance for stent-graft delivery or follow-up. Vascular replicas also help to better understand the limitation of endovascular approaches in challenging anatomy and possibly improve surgical planning or training by practicing high risk clinical procedures in the laboratory to improve outcomes in the operating room. Most AAA phantoms available have a very basic anatomy, which is not representative of the clinical reality. This paper presents a method of fabrication of a realistic AAA phantom with a visible thrombus, as well as some mechanical properties characterizing such phantom. METHODS A realistic AAA geometry replica of a real patient anatomy taken from a multidetector computed tomography (CT) scan was manufactured. To demonstrate the multimodality imaging capability of this new phantom with a thrombus visible in magnetic resonance (MR) angiography, CT angiography (CTA), digital subtraction angiography (DSA), and ultrasound, image acquisitions with all these modalities were performed by using standard clinical protocols. Potential use of this phantom for stent deployment was also tested. A rheometer allowed defining hyperelastic and viscoelastic properties of phantom materials. RESULTS MR imaging measurements of SNR and CNR values on T1 and T2-weighted sequences and MR angiography indicated reasonable agreement with published values of AAA thrombus and abdominal components in vivo. X-ray absorption also lay within normal ranges of AAA patients and was representative of findings observed on CTA, fluoroscopy, and DSA. Ultrasound propagation speeds for developed materials were also in concordance with the literature for vascular and abdominal tissues. CONCLUSIONS The mimicked abdominal tissues, AAA wall, and surrounding thrombus were developed to match imaging features of in vivo MR, CT, and ultrasound examinations. This phantom should be of value for image calibration, segmentation, and testing of endovascular devices for AAA endovascular repair.
Collapse
Affiliation(s)
- Louise Allard
- Laboratory of Biorheology and Medical Ultrasonics, Research Center, University of Montreal Hospital (CRCHUM), Québec H2L 2W5, Canada
| | | | | | | | | | | |
Collapse
|
21
|
Fahy P, Delassus P, McCarthy P, Sultan S, Hynes N, Morris L. An In Vitro Assessment of the Cerebral Hemodynamics Through Three Patient Specific Circle of Willis Geometries. J Biomech Eng 2013; 136:011007. [DOI: 10.1115/1.4025778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Indexed: 11/08/2022]
Abstract
The Circle of Willis (CoW) is a complex pentagonal network comprised of fourteen cerebral vessels located at the base of the brain. The collateral flow feature within the circle of Willis allows the ability to maintain cerebral perfusion of the brain. Unfortunately, this collateral flow feature can create undesirable flow impact locations due to anatomical variations within the CoW. The interaction between hemodynamic forces and the arterial wall are believed to be involved in the formation of cerebral aneurysms, especially at irregular geometries such as tortuous segments, bends, and bifurcations. The highest propensity of aneurysm formation is known to form at the anterior communicating artery (AcoA) and at the junctions of the internal carotid and posterior communicating arteries (PcoAs). Controversy still remains as to the existence of blood flow paths through the communicating arteries for a normal CoW. This paper experimentally describes the hemodynamic conditions through three thin walled patient specific models of a complete CoW based on medical images. These models were manufactured by a horizontal dip spin coating method and positioned within a custom made cerebral testing system that simulated symmetrical physiological afferent flow conditions through the internal carotid and vertebral arteries. The dip spin coating procedure produced excellent dimensional accuracy. There was an average of less than 4% variation in diameters and wall thicknesses throughout all manufactured CoW models. Our cerebral test facility demonstrated excellent cycle to cycle repeatability, with variations of less than 2% and 1% for the time and cycle averaged flow rates, respectively. The peak systolic flow rates had less than a 4% variation. Our flow visualizations showed four independent flow sources originating from all four inlet arteries impacting at and crossing the AcoA with bidirectional cross flows. The flow paths entering the left and right vertebral arteries dissipated throughout the CoW vasculature from the posterior to anterior sides, exiting through all efferent vessels. Two of the models had five flow impact locations, while the third model had an additional two impact locations within the posterior circulation caused by an additional bidirectional cross flows along the PcoAs during the accelerating and part of the decelerating phases. For a complete CoW, bidirectional cross flows exist within the AcoA and geometrical variations within the CoW geometry can either promote uni- or bidirectional cross flows along the PcoAs.
Collapse
Affiliation(s)
| | - Patrick Delassus
- Galway Medical Technologies Centre (GMedTech), Department of Mechanical and Industrial Engineering, Galway Mayo Institute of Technology, Dublin Road, Galway,Ireland
| | - Peter McCarthy
- Department of Diagnostic Radiology, University Hospital, Newcastle Road, Galway,Ireland
| | - Sheriff Sultan
- Department of Vascular and Endovascular Surgery, Western Vascular Institute, University Hospital, Newcastle Road, Galway,Ireland
- Department of Vascular and Endovascular Surgery, Galway Clinic, Doughiska, Galway, Ireland
| | - Niamh Hynes
- Department of Vascular and Endovascular Surgery, Galway Clinic, Doughiska, Galway,Ireland
| | - Liam Morris
- Galway Medical Technologies Centre (GMedTech), Department of Mechanical and Industrial Engineering, Galway Mayo Institute of Technology, Dublin Road, Galway,Ireland e-mail:
| |
Collapse
|
22
|
An Alternative Method to Create Highly Transparent Hollow Models for Flow Visualization. Int J Artif Organs 2013; 36:131-4. [DOI: 10.5301/ijao.5000171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2012] [Indexed: 11/20/2022]
Abstract
Aim Transparent hollow models are needed to visualize and quantify flow in various applications. To obtain the final transparent model, an intermediate molding of the fluid space with an easily removable material is required. Currently used materials to produce this intermediate molding have limitations: toxicity, cost, and a tendency to penetrate the final model, thereby degrading its transparency. In this work an alternative method is presented using chocolate as the fluid-space molding material. Methods Starting from a three-dimensional computer aided design (CAD) geometry, a fluid space model of a human aorta was produced out of chocolate. The replica was coated and cast in a block of highly transparent silicone (Sylgard184; Dow-Corning, Midland, MI, USA). After the silicone was cured, the chocolate was removed using hot water. The geometric accuracy of the fluid-space mold and the transparency of the final model were investigated. Results The mean divergence of the chocolate fluid-space mold from the original geometry was 5.7%. The silicone casting had no defects and perfect transparency for particle tracking. Fluid boundaries were invisible when tested with a fluid whose refractive index matched silicone. Conclusions The process we describe is a cheap and effective way to create transparent models that have excellent optical quality.
Collapse
|
23
|
Deplano V, Meyer C, Guivier-Curien C, Bertrand E. New insights into the understanding of flow dynamics in an in vitro model for abdominal aortic aneurysms. Med Eng Phys 2012; 35:800-9. [PMID: 22981221 DOI: 10.1016/j.medengphy.2012.08.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 06/05/2012] [Accepted: 08/17/2012] [Indexed: 10/27/2022]
Abstract
An in vitro dynamics set-up of the flow in a compliant abdominal aortic aneurysm (AAA) model with an anterior posterior asymmetry, aorto-iliac bifurcation, and physiological inlet flow rate and outlet pressure waveforms was developed. The aims were first to show that the structural mechanical behavior of the used material to mimic the AAA wall was similar to this of patients with AAA and then to study the influence of the aorto-iliac bifurcation presence and to study the influence of the imbalanced flow rate in the iliac branches on the AAA flow field. 3D visualizations, never performed in the literature, have clearly put into evidence the development of a vortex ring generated at the AAA proximal neck during the decelerating phase of flow rate, which detaches and progresses downstream during the cardiac cycle, impinges on the anterior wall in the distal AAA region, breaks up, and separates into two vortices of which one rolls on upstream along the anterior wall. 2D particle image velocimetry measurements, swirling strength and enstrophy calculations allowed quantification of the vorticity, vortex trajectory and energy for the different geometrical and hydrodynamical conditions. The main results show that the instant and the intensity of the vortex ring impingement depend on the presence of the aorto-iliac bifurcation, with higher intensity, by about 90%, for an AAA without bifurcation. The imbalance of the flow rates into the iliac branches induces different propagation velocities of the vortex ring and lowers the intensity of the vortex impact by about 60%. The potential influence of the AAA dynamics is discussed in terms of AAA remodeling and rupture.
Collapse
|
24
|
Use of the photoelastic method and finite element analysis in the assessment of wall strain in abdominal aortic aneurysm models. J Biomech 2012; 45:1759-68. [DOI: 10.1016/j.jbiomech.2012.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 04/20/2012] [Accepted: 05/02/2012] [Indexed: 11/19/2022]
|
25
|
Tierney ÁP, Callanan A, McGloughlin TM. Use of Regional Mechanical Properties of Abdominal Aortic Aneurysms to Advance Finite Element Modeling of Rupture Risk. J Endovasc Ther 2012; 19:100-14. [DOI: 10.1583/11-3456.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
|
26
|
Desai M, Ahmed M, Darbyshire A, You Z, Hamilton G, Seifalian AM. An Aortic Model for the Physiological Assessment of Endovascular Stent-Grafts. Ann Vasc Surg 2011; 25:530-7. [DOI: 10.1016/j.avsg.2010.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 12/22/2010] [Accepted: 12/24/2010] [Indexed: 11/25/2022]
|
27
|
Ene F, Gachon C, Delassus P, Carroll R, Stefanov F, O'Flynn P, Morris L. In vitro evaluation of the effects of intraluminal thrombus on abdominal aortic aneurysm wall dynamics. Med Eng Phys 2011; 33:957-66. [PMID: 21478044 DOI: 10.1016/j.medengphy.2011.03.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 03/12/2011] [Accepted: 03/14/2011] [Indexed: 10/18/2022]
Abstract
The optimum time to treat abdominal aortic aneurysms (AAAs) still remains an uncertain issue. The decision to intervene does not take in account the effects that wall curvature, intraluminal thrombus (ILT) properties and thickness have on rupture. The role of ILT in aneurysm dynamics and rupture has been controversial. In vitro testing of four silicone AAA models incorporating the ILT and aortic bifurcation was studied under physiological conditions. Pressures (P) and diameters (D) were analysed for models with and without ILT at different locations. The diametral strain, compliance and P/D curves were influenced by the presence, elastic stiffness and thickness of the ILT. In this case, the inclusion of ILT reduced the lumen area by 77% that resulted in a 0.5-81% reduction in compliance depending on ILT properties. With an increase in ILT stiffness from 0.05 to 0.2 MPa, the compliance was reduced by 81%. In the region of maximum diameter, there was a reduction of diametral strain and compliance except for the softer ILT which was more compliant throughout the proximal region. The shifting of the maximum diametral strain and compliance to the proximal neck was pronounced by an increase in ILT stiffness, thus creating a possible rupture site.
Collapse
Affiliation(s)
- Florentina Ene
- Department of Mechanical Engineering, Galway Medical Technologies Centre (GMedTech), Galway Mayo Institute of Technology (GMIT), Dublin Road, Galway, Ireland.
| | | | | | | | | | | | | |
Collapse
|
28
|
Corbett TJ, Molony DS, Callanan A, McGloughlin TM. The effect of vessel material properties and pulsatile wall motion on the fixation of a proximal stent of an endovascular graft. Med Eng Phys 2010; 33:106-11. [PMID: 20947409 DOI: 10.1016/j.medengphy.2010.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 09/21/2010] [Accepted: 09/22/2010] [Indexed: 10/18/2022]
Abstract
Migration is a serious failure mechanism associated with endovascular abdominal aortic aneurysm (AAA) repair (EVAR). The effect of vessel material properties and pulsatile wall motion on stent fixation has not been previously investigated. A proximal stent from a commercially available stent graft was implanted into the proximal neck of silicone rubber abdominal aortic aneurysm models of varying proximal neck stiffness (β=25.39 and 20.44). The stent was then dislodged by placing distal force on the stent struts. The peak force to completely dislodge the stent was measured using a loadcell. Dislodgment was performed at ambient pressure with no flow (NF) and during pulsatile flow (PF) at pressures of 120/80 mmHg and 140/100 mmHg to determine if pulsatile wall motions affected the dislodgement force. An imaging analysis was performed at ambient pressure and at pressures of 120 mmHg and 140 mmHg to investigate diameter changes on the model due to the radial force of the stent and internal pressurisation. Stent displacement forces were ~50% higher in the stiffer model (7.16-8.4 N) than in the more compliant model (3.67-4.21 N). The mean displacement force was significantly reduced by 10.95-12.83% from the case of NF to the case of PF at 120/80 mmHg. A further increase in pressure to 140/120 mmHg had no significant effect on the displacement force. The imaging analysis showed that the diameter in the region of the stent was 0.37 mm greater in the less stiff model at all the pressures which could reduce the fixation of the stent. The results suggest that the fixation of passively fixated aortic stents could be comprised in more compliant walls and that pulsatile motions of the wall can reduce the maximum stent fixation.
Collapse
Affiliation(s)
- T J Corbett
- Centre for Applied Biomedical Engineering Research (CABER), MSSi, Department of Mechanical and Aeronautical Engineering, University of Limerick, Limerick, Ireland
| | | | | | | |
Collapse
|
29
|
McGloughlin TM, Doyle BJ. New Approaches to Abdominal Aortic Aneurysm Rupture Risk Assessment. Arterioscler Thromb Vasc Biol 2010; 30:1687-94. [PMID: 20508202 DOI: 10.1161/atvbaha.110.204529] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Timothy M. McGloughlin
- From Centre for Applied Biomedical Engineering Research, Department of Mechanical and Aeronautical Engineering, and the Materials and Surface Science Institute, University of Limerick, Ireland
| | - Barry J. Doyle
- From Centre for Applied Biomedical Engineering Research, Department of Mechanical and Aeronautical Engineering, and the Materials and Surface Science Institute, University of Limerick, Ireland
| |
Collapse
|
30
|
Corbett TJ, Callanan A, O'Donnell MR, McGloughlin TM. An Improved Methodology for Investigating the Parameters Influencing Migration Resistance of Abdominal Aortic Stent-Grafts. J Endovasc Ther 2010; 17:95-107. [DOI: 10.1583/09-2920.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|