BACKGROUND:Braided stents are widely used for treating stenotic arteries due to their good flexibility,but they have significant limitations in providing adequate radial support.OBJECTIVE:In response to the lack of radial support of braided stents made of a single material,a mixed braided stent using biodegradable materials with different mechanical parameters was developed to explore the influencing factors affecting the radial mechanical properties of the mixed braided stent.METHODS:Fe-alloy yarn was introduced into the Mg-alloy stents,and the stents with various braiding parameters were analyzed using finite element analysis.The radial support,radial recoil and expansion non-uniformity of the mixed braided stents were evaluated by comparing with ordinary 0.18 mm Mg-alloy stents prepared by yarn.RESULTS AND CONCLUSION:(1)When the Fe-alloy yarn diameters were 0.18 mm and 0.14 mm,the radial support force of the stent increased continuously with the introduction of more and more Fe-alloy yarns.Although the radial support provided was less by the 0.14 mm Fe-alloy yarns than by the same number of 0.18 mm Fe-alloy mixed braided stents,an increase in the number of Fe-alloy yarns resulted in a radial support comparable to that of the thicker Fe-alloy yarns.When the Fe-alloy yarn diameter was 0.10 mm,the radial support of the stents decreased with the increase in the number of Fe-alloy yarns.(2)When the braiding angle was increased,the radial support force of the stents was reduced,but the radial recoil and expansion non-uniformity were improved.By adjusting the braided angle,the lack of radial support force caused by small diameter Fe-alloy yarns could be improved.(3)It is concluded that this method can improve the radial mechanical properties of the stent without increasing the yarn diameter.This not only overcomes the limitation of single-material stents,but also provides a new idea for the design of multi-material stents.

BACKGROUND:Braided stents are widely used for treating stenotic arteries due to their good flexibility,but they have significant limitations in providing adequate radial support.OBJECTIVE:In response to the lack of radial support of braided stents made of a single material,a mixed braided stent using biodegradable materials with different mechanical parameters was developed to explore the influencing factors affecting the radial mechanical properties of the mixed braided stent.METHODS:Fe-alloy yarn was introduced into the Mg-alloy stents,and the stents with various braiding parameters were analyzed using finite element analysis.The radial support,radial recoil and expansion non-uniformity of the mixed braided stents were evaluated by comparing with ordinary 0.18 mm Mg-alloy stents prepared by yarn.RESULTS AND CONCLUSION:(1)When the Fe-alloy yarn diameters were 0.18 mm and 0.14 mm,the radial support force of the stent increased continuously with the introduction of more and more Fe-alloy yarns.Although the radial support provided was less by the 0.14 mm Fe-alloy yarns than by the same number of 0.18 mm Fe-alloy mixed braided stents,an increase in the number of Fe-alloy yarns resulted in a radial support comparable to that of the thicker Fe-alloy yarns.When the Fe-alloy yarn diameter was 0.10 mm,the radial support of the stents decreased with the increase in the number of Fe-alloy yarns.(2)When the braiding angle was increased,the radial support force of the stents was reduced,but the radial recoil and expansion non-uniformity were improved.By adjusting the braided angle,the lack of radial support force caused by small diameter Fe-alloy yarns could be improved.(3)It is concluded that this method can improve the radial mechanical properties of the stent without increasing the yarn diameter.This not only overcomes the limitation of single-material stents,but also provides a new idea for the design of multi-material stents.