Scientists Use Computer Modelling to Develop Better Stents

Suncica Canic, a professor at the University of Houston, uses computer models to design stents. Here, a 3-D computer model of a stent. Credit: Suncica Canic, Mate Kosor and Josip Tambaca; University of Houston and University of Zagreb

Even though stents are designed to be compatible with the human body, they sometimes cause unwanted reactions such as blood clots and scar tissue formation, explains Stephanie Dutchen from the NIGMS/NIH. So, scientists have tried to coat stents with cells that make the tiny tubes even more compatible. But these, too, aren’t yet perfect, says Suncica Canic, a professor of mathematics at the University of Houston. Blood flowing over a coated stent can still clot or tear cells away. This is, as Canic put it, “not good.” Supported by a joint grant from the National Science Foundation (NSF) and the National Institutes of Health’s National Institute of General Medical Science (NIH/NIGMS), Cancic makes computer models to guide the search for a better stent coating.

She also uses computer models to study the strengths and weaknesses of different stent structures. Her work could help manufacturers optimise stent design and help doctors choose the right stents for their patients, ultimately improving patient outcomes.

Computer scientists usually model stents in three dimensions. Keeping track of about 200,000 points, or nodes, along the stent mesh, the models are massive.

Together with her collaborator, Josip Tambaca of the University of Zagreb in Croatia, and her doctoral student, Mate Kosor, Canic wrote a much simpler program that approximates stents as meshes of one-dimensional rods. This program let the researchers achieve the same result using just 400 nodes.

Using their simplified model, the researchers have examined the designs of several stents on the market to see which structures seem to be best for specific blood vessels or procedures. For instance, they found that stents with an “open design”—where every other horizontal rod is taken out—bend easily, which makes them good to put in curvy coronary arteries.

Canic and Tambaca have also used the model to design a stent with mechanical properties specifically tailored to an experimental heart-valve replacement procedure. She found that this specialised stent works best for the procedure when it’s stiff in the middle and less stiff at the ends. In addition, she has found that combining “bendiness” with radial stiffness—where you can bend the stent into a U shape, but you can’t squeeze the tube shut—produces a stent with less chance of buckling than those that are currently in use.

More information on the research is available from the National Science Foundation.

Tags: stents, Suncica Canic, University of Houston, University of Zagreb