Axial stent strut angle influences wall shear stress after stent implantation: analysis using 3D computational fluid dynamics models of stent foreshortening.
BACKGROUND
The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD) models suggest that the vascular geometry created by an implanted stent causes local alterations in wall shear stress (WSS) that are associated with neointimal hyperplasia (NH). Foreshortening is a potential limitation of stent design that may affect stent performance and the rate of restenosis. The angle created between axially aligned stent struts and the principal direction of blood flow varies with the degree to which the stent foreshortens after implantation.


METHODS
In the current investigation, we tested the hypothesis that stent foreshortening adversely influences the distribution of WSS and WSS gradients using time-dependent 3D CFD simulations of normal arteries based on canine coronary artery measurements of diameter and blood flow. WSS and WSS gradients were calculated using conventional techniques in ideal (16 mm) and progressively foreshortened (14 and 12 mm) stented computational vessels.


RESULTS
Stent foreshortening increased the intrastrut area of the luminal surface exposed to low WSS and elevated spatial WSS gradients. Progressive degrees of stent foreshortening were also associated with strut misalignment relative to the direction of blood flow as indicated by analysis of near-wall velocity vectors.


CONCLUSIONS
The current results suggest that foreshortening may predispose the stented vessel to a higher risk of neointimal hyperplasia.
LaDisa
John F
JF
Division of Cardiology, Department of Pediatrics, Stanford University, Palo Alto, California, USA. jladisa@stanford.edu
Olson
Lars E
LE
Hettrick
Douglas A
DA
Warltier
David C
DC
Kersten
Judy R
JR
Pagel
Paul S
PS
D000818:Animals; D001158:Arteries / Q000502:physiology* / Q000601:surgery*; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D001807:Blood Vessel Prosthesis; D003198:Computer Simulation; D017076:Computer-Aided Design; D004548:Elasticity; D019544:Equipment Failure Analysis / Q000379:methods; D006801:Humans; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods*; D033081:Shear Strength; D015607:Stents; D013314:Stress, Mechanical