Prediction of Mechanical Behavior of Balloon-Expandable Stents

Coronary heart disease is a major health threat for people in the developed countries. Narrowing of the coronary arteries is one of the most common types of coronary heart diseases and is often treated by percutaneous transluminal coronary angioplasty (PTCA) and recently by stenting. A stenting procedure involves inserting a slotted metal tube or coil into the artery and expanding it to help achieve a sufficient luminal size. To optimize the design of stents, we have developed a finite element model of the stenting procedure. The results showed the distal ends of the stent could damage arteries due to non-uniform expansion of the stent. Our model also showed that inclusion of the plaque and artery is important for predicting the final stent shape and diameter. A response surface of the stent hoop stiffness is proposed to help designers quickly decide the stiffness of the stent for a given design. Results show that contact stresses are inversely proportional to stent stiffness and a minimum stent hoop stiffness is needed to prevent stent collapse after balloon removal.