Stent Simulations
The buildup of plaque in the arteries, caused by conditions such as hypertension or diabetes, can lead to an increased risk of stroke and other severe heart issues. To treat this buildup, doctors most often implant a stent in the coronary artery, which is a long, narrow tube that forces the artery open, allowing blood flow.
Drug-eluting stents are the most recent innovation in the field of stent design. These stents contain a plastic component, filled by a drug that treats the plaque buildup. They’ve been shown to perform better than traditional wire stents, and are quickly becoming cardiologists’ first choice for treatment.
There are only about ten DES currently approved for use in humans. Shown below in the flat-mesh form, the geometric properties of these stents vary widely.
Because most stent design is done outside of the academic world, there is little public information about the effect of stent design decisions. For example, are curved corners more effective than pointed corners? What’s the effect of linking layers directly, versus having a connector?
In this project, I sought to answer these questions by, firstly, designing the DES in SolidWorks with a uniform length, width, and wire thickness; secondly, running artery-mimicking simulations on the stents to characterize their behavior; and thirdly, connecting these results to the available literature on stent geometry and efficacy.
To design the stents, I used the mesh-pictures to create a mesh sheet in SolidWorks, then wrapped it around a cylinder. You can see the conversion of one of the stents below:
I did this for all of the stents pictured in the first picture.
The simulations I then ran looked at two properties of the stents: (1) How bendable each stent was, and (2) What the response to arterial pressure was. As such properties have been linked to stent longevity in the body, I could then compare these results to their associated geometries.
Examples of both simulations are shown below.
I’m also including the tables I generated as results from the simulations (named according to the order in the first picture).
The Bend-Test table shows the maximum displacement when one side of the stent is fixed and the other has a downwards pressure applied.
The Pressure-Test results show the radial and the longitudinal displacement when an artery-like pressure is applied to the outside of the stent uniformly. Though force was not cycled, like it would be in a real artery, the stent material is the same, so we can still see a good comparison.
You can look at a brief presentation of my project here, and also view the full paper I compiled with procedure/conclusions here. The study is obviously imperfect, but it can serve as a launchpad for similar studies that can give more accurate results.