Geometrical enhancements for abdominal aortic stent-grafts.
OBJECTIVE
To compare the function of 2 stent-graft designs for endovascular abdominal aortic aneurysm repair.


METHODS
Computational fluid dynamics was used to investigate the performance of a conventional stent-graft versus one with a novel tapered configuration (equal area ratios at the inlet and bifurcation). Idealized geometries (uniplanar) were formed first for both devices. To mimic the clinical setting with pulsatile blood flow, a realistic model (multiplanar) was created for the conventional stent-graft based on computed tomography scans from 3 patients with different aortic geometries. A similar model was created for the tapered stent-graft by mimicking the deployment of the conventional stent-graft through its centerline.


RESULTS
The tapered stent-graft model demonstrated reduced secondary flow vortices and wall shear stresses in the iliac limbs compared to the conventional graft in the idealized scenario. The drag forces in the idealized models were similar for both designs, though the tapered stent-graft showed a 4% reduction. Flow was split more evenly between the tapered stent-graft limbs in the realistic scenario.


CONCLUSIONS
The novel tapered design reduced flow velocities and secondary flows due to its smooth trunk-to-limb transition, while also splitting the flow between the iliac limbs more evenly. In multiplanar models, the out-of-plane curvature was the greatest cause of skewed flow, which reduced the benefits of the tapered stent-graft.
Molony
David S
DS
Centre for Applied Biomedical Engineering Research (CABER) and the Materials and Surface Science Institute, University of Limerick, Ireland.
Callanan
Anthony
A
Morris
Liam G
LG
Doyle
Barry J
BJ
Walsh
Michael T
MT
McGloughlin
Tim M
TM
D001012:Aorta, Abdominal / Q000601:surgery*; D017544:Aortic Aneurysm, Abdominal / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D008433:Mathematics; D008953:Models, Anatomic; D011474:Prosthesis Design; D015607:Stents