Fabrication and Optimal Design of Biodegradable Polymeric Stents for Aneurysms Treatments.

Xue Han,Xia Wu,Xiongbiao Chen,Michael Kelly

doi:10.3390/jfb8010008

Abstract

An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries of the heart and brain. Biodegradable polymeric stent-assisted coiling is expected to be the ideal treatment of wide-neck complex aneurysms. This paper presents the development of methods to fabricate and optimally design biodegradable polymeric stents for aneurysms treatment. Firstly, a dispensing-based rapid prototyping (DBRP) system was developed to fabricate coil and zigzag structures of biodegradable polymeric stents. Then, compression testing was carried out to characterize the radial deformation of the stents fabricated with the coil or zigzag structure. The results illustrated the stent with a zigzag structure has a stronger radial stiffness than the one with a coil structure. On this basis, the stent with a zigzag structure was chosen for the development of a finite element model for simulating the real compression tests. The result showed the finite element model of biodegradable polymeric stents is acceptable within a range of radial deformation around 20%. Furthermore, the optimization of the zigzag structure was performed with ANSYS DesignXplorer, and the results indicated that the total deformation could be decreased by 35.7% by optimizing the structure parameters, which would represent a significant advance of the radial stiffness of biodegradable polymeric stents.

Highlights

An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries of the heart and brain
Endovascular treatment (EVT) by selective coiling is considered one of the main treatments for intracranial aneurysms, which is limited with respect to the treatment of wide-necked and/or large aneurysms, and recanalization would occur after the EVT treatment
As an emerging fabrication technique, the dispensing-based rapid prototyping (DBRP) technique allows for more accurate control over the scaffold microstructure, facilitating the fabrication of stents as designed [11,12]

Summary

Introduction

An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries of the heart (aortic aneurysm) and brain (cerebral aneurysm). EVT by selective coiling is considered one of the main treatments for intracranial aneurysms, which is limited with respect to the treatment of wide-necked and/or large aneurysms, and recanalization would occur after the EVT treatment To circumvent these limitations, a number of new devices have been developed over the last several decades [3]. Most biodegradable polymeric stents are made with a zigzag structure, but there is no any optimal design method utilized. This often causes weaker mechanical properties compared to native arterial vessels and result in early recoil post implantation [8]. This study is aimed at developing methods for fabrication and optimal design of biodegradable polymeric stents for treating aneurysms. A simulation of compression test was pursued based on finite element model; and a study on optimizing the structure of biodegradable polymeric stents though the ANSYS Design Xplorer was conducted

Material Preparation

Fabrication Method

Comparison between Real Compression Test and Simulation

Findings

Optimization of Biodegradable Polymeric Stents