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Purpose
Inappropriate stent-graft (SG) flexibility has been frequently associated with endovascular aortic repair (EVAR) complications such as endoleaks, kinks, and SG migration, especially in tortuous arteries. Stents derived from auxetic unit cells have shown some potential to address these issues as they offer an optimum trade-off between radial...
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... al. [19] (Fig. 3b), and in the present work (Fig. 3c) is depicted in Fig. 3. The overall behavior of all three SGs are relatively similar, in spite of in the suture modeling strategy and choice of elements for the stent and FEM software used. Next, the results for all SG candidates are presented in terms of their global deformation properties in Fig. 4, maximal LR, maximal stresses in the stent, maximal strains in the graft, and torque-bending angle behavior observed during their respective performances in Fig. ...
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... ZLP8 suffered a noticeable kink in its central portion, where the graft was pulled downwards with buckling of the central stents. Among the novel SG designs derived from auxetic unit cells or NUPR unit cells in Fig. 4, it is difficult to isolate any top candidate in comparison based on the global deformation attributes in Fig. 4, with no noticeable ...
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... ZLP8 suffered a noticeable kink in its central portion, where the graft was pulled downwards with buckling of the central stents. Among the novel SG designs derived from auxetic unit cells or NUPR unit cells in Fig. 4, it is difficult to isolate any top candidate in comparison based on the global deformation attributes in Fig. 4, with no noticeable ...
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... noting that AO-LP maintains a consistent and stable torque curve behavior throughout a 180° angulation, a distinctive characteristic when compared to the novel SG candidates derived from auxetic unit cells. The latter exhibit a relatively linear increase in torque magnitude in the range of 60° to 120°, as depicted in Fig. 5e. In the case of ZLP8 (Fig. 4), the formation of kinks in the central region is associated with the torque increase observed between 80° and 150° of angulation. The oscillation seen in the torque-angle curves of SG candidates derived from auxetic unit cells can be attributed to graft wrinkling when being pulled inward by the stents during bending after a 45° ...
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... entire collection of these new SG designs (RE-UL, CRE-UL, CS-UL, RE-DIA, CRE-DIA, CS-DIA). To replicate the invivo deformations that such novel SGs might encounter after deployment in a highly tortuous iliac aneurysm, we adhered to the modeling approach outlined by Demanget et al. [16] and applied specific boundary conditions. As illustrated in Fig. 4, the novel SGs exhibited a noteworthy absence of kinks, displaying uniform distortions consistently along their entire length in their deformed states. This aligns with the findings of Demanget et al. [14,16], who observed that SGs employing circular, spiral, or Z-spiral stents showcased enhanced flexibility compared to standard ...
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... of kinks, displaying uniform distortions consistently along their entire length in their deformed states. This aligns with the findings of Demanget et al. [14,16], who observed that SGs employing circular, spiral, or Z-spiral stents showcased enhanced flexibility compared to standard Z-stented SGs like Zenith-LP. This distinction is evident in Fig. 4, which depicts a noticeable kink in the central area of ZLP8. Importantly, none of the SGs in our study displayed stress magnitudes exceeding 390 MPa, as depicted in Fig. 5a. This indicates that the nitinol stents retained their elastic properties throughout the simulation, suggesting that the novel SGs are unlikely to experience stent ...
