Comparison of Stent Designs using Computational Fluid Dynamics

Coronary artery disease (CAD) is one of the leading causes of death in the developed world. CAD occurs due to the build up of plaque in the coronary arteries which supply fresh blood to the constantly active heart muscle. Several methods exist to alleviate CAD such as coronary artery bypass grafting, balloon angioplasty and coronary stenting. A coronary stent is a small tubular prosthesis which can improve blood flow by acting as a scaffold to prop the diseased artery open. However, stent restenosis (re-blockage) remains a common problem with different stent designs leading to different restenosis rates. This work investigates a relationship between restenosis and the induced flow fields for two different stent designs. Two models have been developed using advanced computational fluid dynamics (CFD) in order to assess the haemodynamic impact of coronary stent implantation. One model represents the left anterior descending (LAD) coronary artery implanted with a Palmaz-Schatz (PS) stent and the second model represents the same artery implanted with a Gianturco-Roubin-II (GR-II) stent. Mathematical models were constructed to simulate the fully developed, non-Newtonian nature of the coronary blood flow. Two flow characteristics that are known to encourage restenosis are low wall shear stress (WSS) and high wall shear stress gradient (WSSG) and both have been identified from the computational simulations. Using data from a recent clinical restenosis trial of the GR-II stent and the PS stent, correlations between flow characteristics and restenosis rates have been investigated.