Looped ends versus open ends braided stent: A comparison of the mechanical behaviour using analytical and numerical methods

Shanahan, Camelia; Tiernan, Peter; Tofail, Syed A. M.

doi:10.1016/j.jmbbm.2017.08.025

Cited by 26 publications

(31 citation statements)

References 20 publications

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“…open-ended stents tend to become compressed and narrowed, but in stents with looped ends, the pressure is conducted to the center of the stent and the local pressure is released by a change in the overall shape of the stent. 23 The stent can also move effortlessly with every movement of the vein. Furthermore, compared with the smooth edges of the looped ends, the sharp wires of the open ends are more harmful to the vein wall.…”

Section: Looped Ends: When the End Of A Stent Is Pressedmentioning

confidence: 99%

Preliminary report of a new type of braided vein stent in animals

Che

Jiang

Líu³

et al. 2018

Phlebology

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Background Iliofemoral vein stenosis or occlusion is a common cause of severe chronic venous insufficiency. Endovascular venous stenting has become a preferred treatment because it is minimally invasive and has a high safety profile. Despite the wide application of the wallstent, it is not specifically designed for veins. There are currently few studies on braided stents in the field of veins. We designed a novel braided vein stent, which has higher radial resistive force and more optimized looped ends structure compared with the wallstent. The purpose of this study was to evaluate the safety and performance of the stent in animals, providing a reference for further clinical trials. Methods The Wallstent is used as a control group. The novel stent and the Wallstent were implanted in the iliac vein of sheep. After 30 days and 90 days, vascular injury, thrombus, neointima coverage, and luminal stenosis were evaluated through venous angiography, endoscopic observation of stent specimen and histopathology. Imaging, histology, and integration data were analyzed by t-test for comparisons between the groups. Results Two groups of stents were successfully implanted. Follow-up observation showed that there was no thrombosis or obstruction >50% occurred in any group and no significant differences in patency, vascular injury, or intimal hyperplasia compared with the Wallstent. Conclusion The novel stent significantly increases the radial resistive force and does not increase vascular injury, thrombus and stent stenosis during 30-day and 90-day follow-up. The next step is to further validate the effectiveness of the stent through long-term animal observation and human clinical trials.

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Section: Looped Ends: When the End Of A Stent Is Pressedmentioning

confidence: 99%

Preliminary report of a new type of braided vein stent in animals

Che

Jiang

Líu³

et al. 2018

Phlebology

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“…[1][2][3][4] During various kinds of BRS, braided stents and laser-cutting stents have been investigated by extensive researches. 2 For the braided stents, the radial strength and flexibility are always considered to be the two dominant indexes 5 for evaluation which are mainly determined by the braiding parameters 6,7 and also affected by the mechanical properties of the weaving monofilament. 8 For the braided stents, the process of shaping the stent by annealing can also affect the mechanical properties of stents.…”

Section: Introductionmentioning

confidence: 99%

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Tian

Zhang

et al. 2021

Polymers for Advanced Techs

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Mechanical properties of poly(L-lactic acid) (PLLA) braided stents are closely related to the performance of the weaving monofilaments. In this study, the PLLA monofilaments were prepared via solid-state drawing (SSD) method and annealed with different constraint methods. Experimental results show that mechanical properties of fabricated monofilaments have been greatly improved by SSD method. With the constrained annealing method, mechanical properties can be further improved while negative effect is shown with unconstrained annealing method. The physicochemical properties of PLLA monofilaments were further characterized, and it is found that the draw ratio of SSD and annealing method can affect the crystallinity and crystallite size, which can directly influence the mechanical properties of the monofilaments.This work tells that it is necessary to consider collectively the effects of SSD method and annealing method of the monofilaments in order to obtain optimized mechanical properties of the braided stents.

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“…There are many methods of evaluating the radial mechanical properties of stents, including radial compression, partial compression, plane compression, and v‐block compression. The equation proposed by Jedwab and Clerc 9 can accurately calculate the radial force of the stent, as confirmed by many scholars 13,23 . Due to the low accuracy of the existing instruments, and the fact that nitinol wires can easily lodge in the compression component of the instrument, the partial compressive test method suggested by Flueckiger et al 24 was used in this study, which is typically used to evaluate the resistance of stents to vascular pulsation.…”

Section: Discussionmentioning

confidence: 77%

“…Four kinds of FD were prepared for each group. The braiding parameters L , D , p , and β were adjusted using Equations (2–6) 13 to give natural porosities P 0 of 61%, 68%, and 75% with a standard number of wires (48 in groups 1–3 and 64 in groups 4–6), while the fourth type (used as a control) had a natural porosity of 68% but a different number of wires (64 in groups 1–3 and 48 in groups 4–6). The subscripts i represent the initial state in Equations (2–6).…”

Section: Methodsmentioning

confidence: 99%

Influence of geometric parameters on partial compressive force and pushing performance of flow diverter

Qiu

Liu

et al. 2021

Numer Methods Biomed Eng

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Research on flow diverter (FD) has progressed over the past decades; however, the relationships between parameters such as stent diameter, porosity, and number of wires and the properties of FDs, such as partial compressive force and push resistance, are not well understood. In this study, the partial compressive force and push resistance of braided FDs with varying porosity (61%–75%), diameter (2.5–5.0 mm), and number of wires (48 or 64) were evaluated using finite element analysis (FEA) and bench tests. At a small compression ratio, the 48‐wire stents exhibited a larger partial compressive force than 64‐wire stents of the same diameter. But when the compression ratio was 50%, the 64‐wire stents had better resistance to pressure. The partial compressive force decreased as the stent diameter increased when all other parameters were equal. However, the influence of the diameter decreased as the stent porosity increased. The push resistance decreased as the porosity and diameter increased, and increased with the number of wires. These results provide useful information for FD design. Decreasing the number of wires can reduce the push resistance, while the push resistance is mainly influenced by the porosity and number of wires, and almost has no relationship with the partial compressive force. The FEA model proved very reliable, and corresponded well to the bench test results, which indicates that this model can be utilized to guide the design of FDs.

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Looped ends versus open ends braided stent: A comparison of the mechanical behaviour using analytical and numerical methods

Cited by 26 publications

References 20 publications

Preliminary report of a new type of braided vein stent in animals

Preliminary report of a new type of braided vein stent in animals

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Influence of geometric parameters on partial compressive force and pushing performance of flow diverter

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