The effect of stent graft oversizing on radial forces considering nitinol wire behavior and vessel characteristics

Implantation sequence modification averts distal stent graft-induced new entry after endovascular repair of Stanford type B aortic dissection

“…4,5 Several issues have been related to the distal SINE formation seen after stent grafting. Distal graft excessive oversizing and lack of tapering in the graft cause increased radial force at the distal end of the endograft, 6 and the increased force, over a period of time, can induce a tear. [7][8][9][10] It has also been suggested that "spring-back", the tendency of a bent, hard tube to return to its original unbent position, can inflict a stress that causes tears at the proximal or distal end of the endograft.…”

Evaluation of a New Approach for Modeling Full Ring Stent Bundles with the Inclusion of Manufacturing Strains

“…In recent investigations, when ring bundles were to be modeled, researchers often adopted the 'equivalent beam' approach. 8,23,24 This technique assumes that a multi-turn bundle can be represented by a 1-turn model as long as the 2nd moment of area for both of them is the same. Although its simplicity is tempting, the drawback of this approach is significant since such a model exaggerates material strain magnitudes because the radius of the wire is increased.…”

“…Direct runtime comparison with other studies in the literature is not trivial since differences in stent geometries, material parameters, the amount of catheter compaction as well as possible exclusion of the cycling steps will inevitably affect the computational cost; reported times from hours to days though can be found in the bibliography. 9,24 Besides the benefits discussed, it is important to mention that some limitations exist. Since the BF model overlaps all Nitinol turns, identification of differences along the width of the bundle is not possible, restricting the capability for a turn-to-turn analysis.…”

“…Such geometries are found in devices like the Anaconda TM (Terumo Aortic, Glasgow, UK) and so far, whenever numerically examined, researchers employ significant simplifications to study them mechanically. The reduction of the number of wire turns, 8,23,24 the omission of the manufacturing process 8,23,24 and the utilization of double symmetry 4,26 are the major modeling techniques followed, all restricting the models' accuracy or applicability. As a result, to the best of the authors' knowledge, there is no model currently available in the literature that can capture the mechanical state of a full ring stent bundle accurately, with the versatility to be applied to complex implant geometry simulations.…”

A Study on the Effects of Struts of Z-Shaped Stent-Grafts on Radial Forces

“…Stent-grafts fixation in the vessel affects the success of endovascular aneurysm repair. Researches indicate that insufficient stent-graft radial force is attributed to post-surgery complications, such as prosthesis migration and endoleak type Ⅰ [3,4]. Endoleak type Ⅰ happens when there is not a complete contact between stent graft rings and vessel wall.…”