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Multiphysics Simulation: An IEEE Spectrum Insert
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Simulating the Release Mechanism in Drug-Eluting Stents

T. Schauer, I. Guler
Boston Scientific Corporation, MN, USA

Stent insertion through the coronary artery is a common procedure used to treat restricted blood flow to the heart caused by stenosis. Following the procedure, restenosis may occur due to excessive tissue growth around the stent. Researchers at Boston Scientific are using multiphysics simulation to better understand how drug-eluting stents prevent tissue regrowth and further improve their design.
In COMSOL Multiphysics, the researchers developed a pore-shell model of a stent coating designed for controlled release of medication into surrounding tissues. In their model, the stiff-spring method was implemented to ensure a continuous diffusive flux of medicine at the pore-shell interface. The Optimization Module was used to refine model parameters that could not be determined experimentally, such as the polymer shell thickness and the retardation coefficient of the pores in the stent coating. Both simulation and experimental data confirm a fast release mechanism from pores and slow diffusion through the polymer encapsulant in the shell.

Predicted medicine concentration in the stent coating for the in vitro case at time = 2 hours.