A study of the radial and bending performance for poly (L‐lactic acid) braided stents with innovative runners

Abstract

Poly (L-lactic acid) (PLLA) braided stent is expected to treat the peripheral vascular and biliary obstructive diseases with its excellent biocompatibility and biodegradability. However, the application of PLLA is still restricted by insufficient mechanical performance. In this paper, a series of PLLA braided stents with runners in axial, circumferential and spiral directions were prepared, and the effects of the runners on the mechanical performance of PLLA braided stents were studied. Meanwhile, the relationship between radial supporting performance and bending performance was analyzed to evaluate the effects on mechanical performance of PLLA stents.According to the relationship, it is found that the runners in different directions have a great influence on the mechanical performance of the stents. Especially the runners in spiral direction can effectively improve the radial force and bending stiffness of the stents compared with the control group. This work provides some suggestions for the development and design of PLLA braided stents in the future.

Evaluation of the stress relaxation behavior of poly (L‐lactic acid) self‐expanding braided stents

“…During the compression stage, the slope of the radial strength at the beginning of the RS‐D curve represents the radial stiffness 35 . At the end of the compression stage, when the test lumen reaches its minimum diameter, the maximum radial loading of stents is defined as the peak compression force (PCF).…”

“…During the compression stage, the slope of the radial strength at the beginning of the RS-D curve represents the radial stiffness. 35 At the end of the compression stage, when the test lumen reaches its minimum diameter, the maximum radial loading of stents is defined as the peak compression force (PCF). Chronic outward force (COF) refers to the radial loading of braided stents acting on the vessel wall at the indicated use diameter (IUD) during expansion stage.…”

Key Factors of Mechanical Strength and Toughness in Oriented Poly(l-lactic acid) Monofilaments for a Bioresorbable Self-Expanding Stent

“…/ n = (4) where σ is the polymer strength. A and B are constants for a different polymer, and M n is the number-average molecular weight.…”

“…As a biodegradable polymer, poly­( l -lactic acid) (PLLA) monofilaments can be prepared via melt extrusion and solid-state drawing, , which are increasingly applied to biomedical devices such as PLLA braided stents − and surgical sutures . Moreover, the high orientation, crystallinity, superior strength, and toughness of the monofilaments, as the fundamental element of the braided stents, are acquired. ,− Nowadays, researchers have made great progress in fabricating high-performance PLLA monofilaments especially for manufacturing technologies. − In particular, PLLA-based implants typically contact the bloodstream or other avascular tissues, which have to be sterilized to eliminate the risks of infection before clinical application. , The complex external and internal environments can also drastically influence the mechanical properties of the monofilament.…”

Enhanced mechanical properties of poly(L‐lactide) braided stent with six‐arm poly(L‐lactide‐co‐ε‐caprolactone) coating cross‐linked by hexamethylene diisocyanate

“…The biodegradable polymer materials for making the stents mainly include polydioxanone (PDO), poly (ε-caprolactone) (PCL), poly(L-lactide) (PLLA), poly(L-lactide-glycolide) (PLGA), and so forth. 4,5 To improve the mechanical properties of biodegradable polymer stents, researchers have studied the material properties, 6 structural parameters, [7][8][9] and physical modification, 10,11 to analyze the factors that can affect the mechanical properties.…”