Problem Specification - Lesson 1

Balloon angioplasty is a procedure where a balloon catheter is loaded with a depressed stent and is passed through the cardiovascular system to the diseased coronary artery. Once in place, the balloon is inflated to a predetermined diameter, causing the balloon and stent to rapidly expand. The balloon forces the stent outwards, breaking up and pushing plaque deposits outward, and clearing the way for blood flow to the nutrient-deprived walls. This expansion also causes plastic deformation of the metal stent, providing a system of truss supports to keep the artery open.

FEA has the ability to identify some mechanical characteristics of coronary artery stents that may not be easily obtained using traditional mechanical testing. The Food and Drug Administration (FDA) recognizes the power of FEA, and recommends that device submissions require simulation as a validation tool; FEA stent submissions often include data on recoil percentage, maximum stresses due to balloon expansion, and residual stresses.

The mechanical responses that occur as a result of expanding the balloon-stent assembly due to balloon inflation are explored, followed by balloon deflation. These steps lead to a successfully deployed coronary artery stent. The final results of this report include detailed FEA of the stent that reflects real-world submission data outlined by the FDA and studied recoil percentage, critical locations of maximum stresses, stress magnitudes at these critical locations, as well as residual stresses due to plastic deformation.

For more information on the FDA's involvement in Stent design and regulation, the following link contains guidance for industry;

http://www.fda.gov/RegulatoryInformation/Guidances/ucm071863.htm

The model generated for this tutorial is a simple stent geometry made solely for the purpose of the tutorial and does not reflect the best stent designs.

We encourage you to try to think up your own!