A finite element study on variations in mass transport in stented porcine coronary arteries based on location in the coronary arterial tree

Abstract

Drug-eluting stents have a significant clinical advantage in late-stage restenosis due to the antiproliferative drug release. Understanding how drug transport occurs between coronary arterial locations can better help guide localized drug treatment options. Finite element models with properties from specific porcine coronary artery sections (left anterior descending (LAD), right (RCA); proximal, middle, distal regions) were created for stent deployment and drug delivery simulations. Stress, strain, pore fluid velocity, and drug concentrations were exported at different time points of simulation (0-180 days). Tests indicated that the highest stresses occurred in LAD sections. Higher-than-resting homeostatic levels of stress and strain existed at upwards of 3.0 mm away from the stented region, whereas concentration of species only reached 2.7 mm away from the stented region. Region-specific concentration showed 2.2 times higher concentrations in RCA artery sections at times corresponding to vascular remodeling (peak in the middle segment) compared to all other segments. These results suggest that wall transport can occur differently based on coronary artery location. Awareness of peak growth stimulators and where drug accumulation occurs in the vasculature can better help guide local drug delivery therapies.

Fig. 1

(a) Top: geometry with representative 1/20 symmetry. Bottom: representative mesh with closeup in inset. (b) Resolute Integrity^® release profile used in the simulations (adapted from Ref. [33]).

Fig. 2

Geometry planes and lines for evaluation. (a) is the planar cut at the end of the stent. i is the line of nodes at the midradius around the θ direction at the end of the stent. ii is the line of nodes in mid-θ along the radius at the end of the stent. (b) is the planar cut in the middle of the stent. iii is the line of nodes at the midradius around the θ direction in the middle of the stent. iv is the line of nodes in mid-θ along the radius in the middle of the stent. (c) is the planar cut at mid-θ. v is the line of nodes at midradius along the length of the vessel section. iv is the line of nodes at the inner surface of the artery along the length of the vessel section.

Fig. 3

Mechanical metrics between section. Top is the maximum principal stress and bottom is the maximum principal strain. Values are averaged over all elements in either the stented or nonstented regions. Contour plot shows a representative maximum principal stress contour plot (in Pa) from a RCA proximal section.

Fig. 4

(a and b) v^fr at line scan v along the length for the different vessel sections. The arrows represent the stented sections of the vessels. Lengths along the vessels are normalized. (c) is the Pecletlike number between arterial sections (Eq. (9)).

Fig. 5

Representative v^fr results (a), and concentration results at times of 18 (b), 36 (c), 72 (d), 126 (e), and 180 days (f). All contour plots are from RCA middle sections.

Fig. 6

Representative concentration values for the i, and iii regions over time for a RCA middle section

Fig. 7

Average values 2over the ii and iv scans over times of 9, 30, and 180 days for (a), (b), and (c), respectively

Fig. 8

Representative concentration (kg/m³) contour plots for right middle sections for a noncell-binding model (a) and a cell-binding model (b)