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Purpose: Balloon-expandable stents are commonly used for the treatment of tracheobronchial strictures. We routinely perform targeted overdilation of these stents 1-2mm on initial deployment to prevent stent migration or allow foreshortening to target airway caliber; however, specific data on the effect of targeted overdilation is unknown., Patients and Methods: We used three iCAST stents (6×22mm, 7×22mm, and 10×38mm) to perform the study. We had two sets of each size to average our results. Targeted overdilation was accomplished with Merit Elation balloons., Results: The 6 × 22 and 7 × 22 stent OD increased from 6 to 11.4mm and 7 to 11.6mm. The 10 × 38 stent demonstrated minimal OD change with overdilation (OD change of 10.4 to 12.2mm). All stents demonstrated significant foreshortening with overdilation (20.2 to 5.65mm, 19.4 to 6mm, and 30.9 to 10.2mm for 6 × 22, 7 × 22, and 10 × 38, respectively). The breakpoint was seen at near twice the stated stent OD (13.5mm, 15mm, and 15mm with 6 × 22, 7 × 22 and 10 × 38, respectively)., Conclusion: We have demonstrated that iCAST stents can increase their OD with subsequent foreshortening during targeted overdilation. This data can help facilitate decisions when selecting a particular iCAST stent for a specific airway application. Additionally, we have highlighted that balloon inflation diameter does not correspond to the actual stent OD during deployment. We believe that this data offers practical information for end-users of this stent type and additional data will be needed to corroborate our findings., Competing Interests: The authors report no conflicts of interest in this work., (© 2021 Wong et al.)

Balloon expandable stents (BES), which are made of stainless steel, are vulnerable to external compression, leading to deformation or collapse/fracture of the stents. In this report, two cases of complete collapse of BES are presented. In both cases, BES were placed in a heavily calcified aorta and subsequently collapsed without any evidence of external compression. Repeated pulsation of heavily calcified aorta was presumed to be the cause of the stent collapse., Competing Interests: Disclosure Statement (COI)SI received a research grant from W. L. Gore; JS received honoraria from Nipro corporation and Abbott; KK received scholarships from Boston Scientific, Terumo corporation, and Gore Japan. The other authors state that they have no conflicts of interest to disclose., (Copyright © 2020 Annals of Vascular Diseases.)

The selection of stent and balloon type is decisive in the stenting process. In the treatment of an eccentric plaque obstruction, a symmetric expansion from stent dilatation generates nonuniform stress distribution, which may aggravate fibrous cap prone to rupture. This paper developed a new stent design to treat eccentric plaque using structural transient dynamic analysis in ANSYS. A non-symmetric structural geometry of stent is generated to obtain reasonable stress distribution safe for the arterial layer surrounding the stent. To derive the novel structural geometry, a Sinusoidal stent type is modified by varying struts length and width, adding bridges, and varying curvature width of struts. An end ring of stent struts was also modified to eliminate dogboning phenomenon and to reduce the Ectropion angle. Two balloon types were used to deploy the stent, an ordinary cylindrical and offset balloon. Positive modification results were used to construct the final non-symmetric stent design, called an Asymmetric stent. Analyses of the deformation characteristics, changes in surface roughness and induced stresses within intact arterial layer were subsequently examined. Interaction between the stent and vessel wall was implemented by means of changes in surface roughness and stress distribution analyses. The Palmaz and the Sinusoidal stent were used for a comparative study. This study indicated that the Asymmetric stent types reduced the central radial recoiling and the dogboning phenomenon. In terms of changes in surface roughness and induced stresses, the Asymmetric stent has a comparable effect with that of the Sinusoidal stent. In addition, it could enhance the distribution of surface roughening as expanded by an offset balloon.

Endovascular stenting has evolved over the last 50 years since its inception into the framework of management of vascular atherosclerotic disease. Stent design has evolved as lesion complexity has increased. Nevertheless, certain first principles regarding stent design have been recapitulated time and again with every iteration of endovascular stents. This article reviews principles of endovascular stent design and compares and contrasts key aspects of balloon expandable and self-expanding stents., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Atherosclerotic iliac artery disease is increasingly being treated with endovascular techniques. A number of new stent technologies can be utilized with high long-term patency, including self-expanding stents, balloon-expandable stents, and covered stents, but comparative data on these stent types and in more complex lesions are lacking. This article provides a review of currently available iliac stent technologies, as well as complex procedural aspects of iliac artery interventions, including approaches to the treatment of iliac bifurcation disease, long segment occlusions, choice of stent type, and treatment of iliac artery in-stent restenosis.

The physical properties of the stent surface influence the effectiveness of vascular disease treatment after stent deployment. During the expanding process, the stent acquires high-level deformation that could alter either its microstructure or the magnitude of surface roughness. This paper constructed a finite element simulation to observe the changes in surface roughness during the stenting process. Structural transient dynamic analysis was performed using ANSYS, to identify the deformation after the stent is placed in a blood vessel. Two types of bare metal stents are studied: a Palmaz type and a Sinusoidal type. The relationship between plaque length and the changes in surface roughness was investigated by utilizing three different length of plaque; plaque length longer than the stent, shorter than the stent and the same length as the stent. In order to reduce computational time, 3D cyclical and translational symmetry was implemented into the FE model. The material models used was defined as a multilinear isotropic for stent and hyperelastic for the balloon, plaque and vessel wall. The correlation between the plastic deformation and the changes in surface roughness was obtained by intermittent pure tensile test using specimen whose chemical composition was similar to that of actual stent material. As the plastic strain is achieved from FE simulation, the surface roughness can be assessed thoroughly. The study found that the plaque size relative to stent length significantly influenced the critical changes in surface roughness. It was found that the length of stent which is equal to the plaque length was preferable due to the fact that it generated only moderate change in surface roughness. This effect was less influential to the Sinusoidal stent.