Effects of Micro-sized Drug Reservoirs on Key Clinical Attributes for Drug-eluting Depot Stents

• Main Authors: Yi-Hsiang Chiu, 邱奕翔
• Other Authors: Hao-Ming Hsiao
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/90705065696457344164

碩士 === 國立臺灣大學 === 機械工程學研究所 === 100 === A stent is a miniature medical device deployed in a stenotic artery to restore the blood flow. In this thesis, we first carried out a sensitivity analysis using the developed finite element models and the parametric stent design to investigate several key clinically-relevant functional attributes recommended by FDA. These key clinical attributes include stresses/strains, fatigue resistance, radial strength, and expansion recoil. The finite element models were able to predict the mechanical integrity of a balloon-expandable stent at various stages such as crimping onto a balloon catheter, stent expansion, radial strength to resist blood vessels from collapsing, and service life in the human body when subjected to pulsatile blood pressure. Subsequently, we used these models to investigate an innovative variation of the drug-eluting stent (DES) with micro-sized drug reservoirs－the depot stent. It allows programmable drug delivery with both spatial and temporal control and has several potential advantages over traditional DESs. However, creating such reservoirs on the stent struts may weaken the structure of the stent scaffolding and compromise its mechanical integrity. Thus, we systematically evaluated the effects of these micro-sized drug reservoirs on stent attributes and proposed an optimized depot stent that could triple drug capacity than the current DESs with marginal trade-off in its attributes. Finally, we introduced a newly-found percutaneous coronary intervention complication called the longitudinal deformation and evaluated the effect of different stent designs on stent longitudinal integrity via computational modeling. We found that the stent strut phase and the connector number had significant effect on stent longitudinal integrity. In summary, the developed analytical schemes allow us to gain deeper insight into the fundamental stent issues and evaluate the mechanical behavior of various stent designs, in the hope to optimize the overall stent attributes.