The Preliminary Study Of The Mechanical Behavior Of Cardiovascular Stents In Coronary Arteries

While people's living standard has been improving, the dietary structure is out of balance and more fatty substance is absorbed. Consequently the incidence of coronary diseases has been rising. At present Percutaneous Transluminal Coronary Angioplasty (PTCA), a minimally invasive surgery, is one of the most popular therapies for the coronary diseases in China. As an important device in the surgery, the stent is a small tube-like structure. After implantation of the stent, restenosis in the vascular lesion and stent fracture are the major barriers to the success of the surgery as clinical report. In this thesis, experimental test and finite element method are applied to investigate the mechanical properties of the stent in the artery.In the experiment, a stent was inserted into the porcine coronary artery and computer tomography (CT) technique was adopted to visualize stent expansion in the artery. After the deployment, anatomy analysis was used to study the mechanical behavior of stent expansion in the artery. We obtained:1. The mechanical properties of stent expansion in artery differ from that out of artery.2. The implantation of the stent brings about compression and damage to the artery wall.Secondly, using numeric simulation, we analyzed the whole process of stent deployment in the blocked artery. The conclusions were as follow:1. During the expansion, stent slides on the artery wall. The sliding movement produces shear stress on the artery wall, and this stress perhaps is the key contributor to the artery wall damage.2. After the stent expands to the nominal diameter, axial tension stress appears on the interface of the plaque and artery. This stress could induce the instability of plaque and artery, and the dissection of plaque from artery is start from the edge.Thirdly, using numeric simulation, we studied the mechanical properties of stent overlapping and its behavior in the blocked artery. We got:1. The normal surface-to-surface contact between stent struts does not occur in the use of overlapped stents.2. During the procedure of overlapping, slide happens among struts. 3. The main reasons of overlapping stents strut broken are the contact pattern and struts sliding.4. The artery damage is more serious in the area where stent overlapped.