Design and Evaluation of Self-Expanding Stents Suitable for Diverse Clinical Manifestation Based on Mechanical Engineering

Abstract

Atherosclerosis is one of the most prominent diseases that induce dysfunction of circulation, and it is a disease of large and medium size arteries. If cholesterol presenting at high concentration in a blood injures an intima, a white corpuscle, i.e. a monocyte, goes into the intima and mutates into a foam cell. Then, smooth muscle cells migrate from the media to the intima, and they grow proliferously there. Based on these phenomena, cholesterol and other lipid materials accumulate in the intima. Atherosclerosis has become a serious problem in the developed countries that are aging. Therefore, countermeasures to the atherosclerosis have become important. Although there are various medical treatments for the atherosclerosis, a stent placement has received much attention as a minimally invasive procedure for vascular stenotic lesion based on the coronary atherosclerosis, the arteriosclerosis obliterans, etc. A stent is a cylindrical tube-shaped medical device that can expand the stenotic lesion in a blood vessel continuously. When considering the expansion method of a stent, two types are available. One is a self-expanding type that can expand by itself when released from the sheath of a catheter. Another is a balloon-expandable type that must be expanded forcibly using a balloon catheter. Because the self-expanding stent continues to expand to the memorized diameter at the stenotic lesion, it has the long-term patency of a vascular wall. In the present study, the main target is the self-expanding type.