Structural implications of fenestrated stent graft misalignment.
BACKGROUND
Endovascular aneurysm repair is a minimally-invasive method for the treatment of abdominal aortic aneurysms. For aneurysms that involve the visceral arteries, a custom-made stent graft with fenestrations for the branch arteries is required. The purpose of the current study is to evaluate the structural impact of misaligned fenestrations with respect to luminal patency and proximal aortic neck apposition in an in vitro model.


METHODS
A custom apparatus was used to evaluate seven Anaconda and three Zenith fenestrated stent grafts. All stent grafts were evaluated at 10° increments of stent/fenestration misalignment up to 80°. Images were captured at each interval and the luminal cross-sectional area and wall apposition were measured.


RESULTS
The Anaconda stent graft, which has an unsupported main body, demonstrated a linear reduction in luminal patency at increasing angles of misalignment (P < 0.0001). Stent/fenestration misalignments of 20° and 80° resulted in decreases in mean luminal patency of 14% and 54% respectively. The Zenith stent graft demonstrated a similar decrease in luminal patency, starting at misalignments of ≥40° (P < 0.0001). However, with stent/fenestration misalignments of ≥30°, apposition between the Zenith stent graft and the simulated aortic neck was compromised suggesting the creation of a type Ia endoleak.


CONCLUSIONS
Both the Anaconda and Zenith devices behave adversely at extreme angles of misalignment with luminal narrowing in the Anaconda device and loss of wall apposition in the Zenith device; however, both stent grafts appear to be equivalent at low angles of misalignment.
Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 164, Toronto, ON, M5S 13G9, Canada; Division of Vascular Surgery, Toronto General Hospital, UHN, 190 Elizabeth St., Toronto, ON, M5G 2C4, Canada.
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Crawford
Division of Engineering Science, University of Toronto, 35 St. George Street, Toronto, ON, M5S 1A4, Canada.
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Itkina
Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada.
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Doyle
Division of Vascular Surgery, Toronto General Hospital, UHN, 190 Elizabeth St., Toronto, ON, M5G 2C4, Canada.
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Tse
Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 164, Toronto, ON, M5S 13G9, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada.
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Amon
Division of Vascular Surgery, Toronto General Hospital, UHN, 190 Elizabeth St., Toronto, ON, M5G 2C4, Canada. Electronic address: graham.roche-nagle@uhn.ca.
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Roche-Nagle
D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects* / Q000379:methods; D057510:Endovascular Procedures / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011475:Prosthesis Failure; D015607:Stents; D016896:Treatment Outcome
Abdominal aortic aneurysm; EVAR; Endograft; Endovascular aneurysm repair; Fenestrated; Misalignment; Stent graft