Computer Simulation Models Stent Drug Behavior

Drug eluting stents can have potential side effects when the chemical gets deposited downstream and causes blood clots to form. To help predict potential problems, MIT scientists developed a model to study how drugs from stents behave around arterial bifurcations.
From the article abstract in PLoS ONE:

Methods and Results
We constructed two-phase computational models of stent-deployed arterial bifurcations simulating blood flow and drug transport to investigate the factors modulating drug distribution when the main-branch (MB) was treated using a DES. Simulations predicted extensive flow-mediated drug delivery in bifurcated vascular beds where the drug distribution patterns are heterogeneous and sensitive to relative stent position and luminal flow. A single DES in the MB coupled with large retrograde luminal flow on the lateral wall of the side-branch (SB) can provide drug deposition on the SB lumen-wall interface, except when the MB stent is downstream of the SB flow divider. In an even more dramatic fashion, the presence of the SB affects drug distribution in the stented MB. Here fluid mechanic effects play an even greater role than in the SB especially when the DES is across and downstream to the flow divider and in a manner dependent upon the Reynolds number.
Conclusions
The flow effects on drug deposition and subsequent uptake from endovascular DES are amplified in bifurcation lesions. When only one branch is stented, a complex interplay occurs – drug deposition in the stented MB is altered by the flow divider imposed by the SB and in the SB by the presence of a DES in the MB. The use of DES in arterial bifurcations requires a complex calculus that balances vascular and stent geometry as well as luminal flow.

Image: Mural drug deposition is a function of relative stent position with respect to the side-branch and Reynolds number in arterial bifurcations. Snapshots of arterial drug deposition patterns for three different stent placement scenarios (upstream (A), midstream (B) and downstream (C)) and five different flow conditions are shown. All the simulated flow conditions were normalized using the mean Reynolds number (Re0) evaluated in the Methods section.
Article in PLoS ONE: Luminal Flow Amplifies Stent-Based Drug Deposition in Arterial Bifurcations
Press release: New computer model could lead to safer stents