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Patient-specific thoracic endovascular aoratic repair (TEVAR)
Endovascular aortic repair (EVAR) is a minimally invasive procedure to treat aortic aneurysms. Current off-the-shelf devices may not fit the patient perfectly, potentially increasing the chance of post-operative complications. This project aims to provide proof of concept for rapidly creating inexpe...
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| Format: | Thesis |
| Language: | English |
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Department of Human Biology
2020
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| _version_ | 1867613321767682048 |
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| access_status_str | Open Access |
| author | Lin, Andrew |
| author2 | Bezuidenhout, Deon |
| author_browse | Bezuidenhout, Deon Lin, Andrew |
| author_facet | Bezuidenhout, Deon Lin, Andrew |
| author_sort | Lin, Andrew |
| collection | Thesis |
| description | Endovascular aortic repair (EVAR) is a minimally invasive procedure to treat aortic aneurysms. Current off-the-shelf devices may not fit the patient perfectly, potentially increasing the chance of post-operative complications. This project aims to provide proof of concept for rapidly creating inexpensive patient-specific EVAR stent-grafts, conforming to the unique anatomy of the patient. After investigating the range of electrospinning shape capabilities on idealised stent-graft geometries (straight, tapered, elliptical, and curved), CT scans was used to create blood and aortic models of an abdominal aortic aneurysm. The former was used to design a patientspecific stent-graft geometry, 3D print a conductive electrospinning mandrel, and electrospin (290 mm, +18 kV, -3 kV, 5 ml/hr, 5 mm/s, 750 rpm) Polyurethane (PU). Sinusoidal Nitinol reinforcement segments were subsequently incorporated into the graft. Various geometries were successfully spun. Electrospun PU scaffolds had a mean ultimate tensile strength of 7.3 MPa, mean Young’s Modulus of 1.9 MPa, and a mean maximum strain of 571%. Fibre morphology analysis showed a mean orientation index of 0.25 (750 rpm) and 0.35 (1000 rpm), mean fibre diameter of 2.3 µm, and a mean pore size of 7.5 µm; pore size indicates possibility of endothelialisation. Nitinol reinforced patient-specific graft was successfully made and stent-grafts of various stent patterns had radial forces between 1.3 to 5.8 N (comparable to 2.8 N from a commercial example). FEA simulation highlighted various advantages of customised stent-grafts that conform to the anatomy over standard cylindrical devices such as better seal and contact traction. Simulation results (25 mm Ø, cylindrical, electrospun stent-graft) showed close approximations to experimental results; its use for future stent-graft design optimisations is promising. Mock insertion of an electrospun patient-specific stent-graft was performed in a 3D-printed transparent-PLA hollow aortic model with good conformity, albeit subpar visibility without a backlight and inflexibility. Although further improvements can be made to the individual steps, proof of principle was achieved. This process is very promising for the manufacturing of patient-specific devices that could offer better long term outcomes. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31136 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:17.944Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Human Biology |
| publisherStr | Department of Human Biology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/31136 Patient-specific thoracic endovascular aoratic repair (TEVAR) Lin, Andrew Bezuidenhout, Deon Thierfelder, Nikolaus biomedical engineering Endovascular aortic repair (EVAR) is a minimally invasive procedure to treat aortic aneurysms. Current off-the-shelf devices may not fit the patient perfectly, potentially increasing the chance of post-operative complications. This project aims to provide proof of concept for rapidly creating inexpensive patient-specific EVAR stent-grafts, conforming to the unique anatomy of the patient. After investigating the range of electrospinning shape capabilities on idealised stent-graft geometries (straight, tapered, elliptical, and curved), CT scans was used to create blood and aortic models of an abdominal aortic aneurysm. The former was used to design a patientspecific stent-graft geometry, 3D print a conductive electrospinning mandrel, and electrospin (290 mm, +18 kV, -3 kV, 5 ml/hr, 5 mm/s, 750 rpm) Polyurethane (PU). Sinusoidal Nitinol reinforcement segments were subsequently incorporated into the graft. Various geometries were successfully spun. Electrospun PU scaffolds had a mean ultimate tensile strength of 7.3 MPa, mean Young’s Modulus of 1.9 MPa, and a mean maximum strain of 571%. Fibre morphology analysis showed a mean orientation index of 0.25 (750 rpm) and 0.35 (1000 rpm), mean fibre diameter of 2.3 µm, and a mean pore size of 7.5 µm; pore size indicates possibility of endothelialisation. Nitinol reinforced patient-specific graft was successfully made and stent-grafts of various stent patterns had radial forces between 1.3 to 5.8 N (comparable to 2.8 N from a commercial example). FEA simulation highlighted various advantages of customised stent-grafts that conform to the anatomy over standard cylindrical devices such as better seal and contact traction. Simulation results (25 mm Ø, cylindrical, electrospun stent-graft) showed close approximations to experimental results; its use for future stent-graft design optimisations is promising. Mock insertion of an electrospun patient-specific stent-graft was performed in a 3D-printed transparent-PLA hollow aortic model with good conformity, albeit subpar visibility without a backlight and inflexibility. Although further improvements can be made to the individual steps, proof of principle was achieved. This process is very promising for the manufacturing of patient-specific devices that could offer better long term outcomes. 2020-02-17T11:33:04Z 2020-02-17T11:33:04Z 2019 2020-02-17T10:06:15Z Master Thesis Masters MSc http://hdl.handle.net/11427/31136 eng application/pdf Department of Human Biology Faculty of Health Sciences |
| spellingShingle | biomedical engineering Lin, Andrew Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| thesis_degree_str | Master's |
| title | Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| title_full | Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| title_fullStr | Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| title_full_unstemmed | Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| title_short | Patient-specific thoracic endovascular aoratic repair (TEVAR) |
| title_sort | patient specific thoracic endovascular aoratic repair tevar |
| topic | biomedical engineering |
| url | http://hdl.handle.net/11427/31136 |
| work_keys_str_mv | AT linandrew patientspecificthoracicendovascularaoraticrepairtevar |