A Computational Analysis of the Deformation of the Femoropopliteal Artery With Stenting

Abstract

Physiological loads that act on the femoropopliteal artery, in combination with stenting, can lead to uncharacteristic deformations of the stented vessel. The overall goal of this study was to investigate the effect of stent length and stent location on the deformation characteristics of the superficial femoral artery (SFA) using an anatomically accurate, three-dimensional finite element model of the leg. For a range of different stent lengths and locations, the deformation characteristics (length change, curvature change, and axial twist) that result from physiological loading of the SFA along with the mechanical behavior of the vessel tissue are investigated. Results showed that stenting portions of the SFA leads to a change in global deformation characteristics of the vessel. Increased stress and strain values and altered deformation characteristics were observed in the various stented cases of this study, which are compared to previous results of an unstented vessel. The study concludes that shortening, twist and curvature characteristics of the stented vessel are dependent on stent length and stent location within the vessel.

Stent Design Affects Femoropopliteal Artery Deformation

“…No stent appears to accommodate all deformation modes without either exacerbating or restricting baseline deformations. Restriction of foreshortening within the stented segment observed in this study agrees with previous findings in patient 4,19 , cadaver 20 , and computational models 21 , and the amount of restriction for different devices correlates with device stiffness in compression determined with bench-top tests 8 . In these tests the Viabahn stent-graft restricted foreshortening the least, likely due to its helically wrapped wire around specially designed PTFE fabric, while most other devices contained multiple, rigid longitudinal connectors that restricted foreshortening.…”

Deformation of the Femoropopliteal Segment

“…While vessel shortening and increased curvature during knee flexion in both unstented and stented vessels have been widely reported, 1,2,5-7,10-17 this study for the first time found that more flexible stents accommodate shortening better than axially stiffer stents under axial compression during hip/knee flexion. Figure 6B demonstrates that stiffer stents, which shorten less, are associated with higher levels of curvature in the bare vessel immediately distal to the implanted stent.…”

“…Such kinking and buckling of the vessel at the ends of the stented segment has been associated with high stress concentrations within the vessel tissue, which may contribute to injury. 7 Clinical experience with FP stents has shown a positive correlation between stent flexibility and resistance to fracture. 8…”

Impact of alterations in target vessel curvature on branch durability after endovascular repair of thoracoabdominal aortic aneurysms

“…Significant increase in the stress and strain on the stent, whether BES or SES, has been observed in the femoropopliteal system and the coronary artery system and affects long-term patency. [12][13][14] In addition, in vitro models assessing the influence of target vessel morphology demonstrate considerable alteration in stent function related to the underlying stent design in the curved vessel. 15,16 Stent placement in curved segments also can induce profound alterations in local hemodynamics affecting secondary flow patterns, pressure gradient change, and vorticity.…”