For patients with symptomatic coronary artery disease, the best course of action often involves implanting a drug-eluting stent into the artery where a plaque buildup is blocking blood flow to the heart. The metallic stent props the artery open while releasing a drug that helps to suppress restenosis — the re-closure of the artery due to excess tissue growth around the stent. However, the body's response to tissue inflammation and arterial injury around the stent's edges can still sometimes cause restenosis.
In a paper that published in the SIAM Journal on Applied Mathematics, Sunčica Čanić, Yifan Wang (both of the University of California, Berkeley), and Martina Bukač (University of Notre Dame) develop mathematical models that represent a drug-eluting stent in an artery and investigate how the stent affects arterial tissue permeability and blood flow. "I believe that our work may help clinical workers understand certain pathologies of stent-related restenosis and eventually improve patient outcomes," Wang said.
To accomplish this objective, the authors used several novel elements that are not present in previous stent models. "For the first time in our study, drug-eluting stents were computationally evaluated based on their performance in moving arteries modeled as poroelastic materials, with arterial wall permeability depending on the deformation of the arterial wall," Čanić said. Poroelastic materials are solids with many pores through which fluids can flow, like sponges or the biological tissues that make up artery walls. The degree to which fluids can permeate the tissue wall depends on changes in the volume of the pores.
"We showed that the presence of a stent affects the deformation of the arterial tissue at the stent location, which changes the permeability properties of the tissue," Čanić said. "This, in turn, influences how an anti-inflammatory drug that coats the stent penetrates the tissue and prevents inflammation."
