Coronary stent implantation changes 3-D vessel geometry and 3-D shear stress distribution

Mechanisms of in-stent restenosis are not fully understood. Shear stress is known to play a role in plaque and thrombus formation and is sensitive to changes in regional vessel geometry. Hence, we evaluated the regional chang es in 3-D geometry and shear stress induced by stent placement in coronary arteries of pigs. Methods. 3-D reconstruction was performed, applying a combined angiographic and IVUS technique (ANGUS), from seven Wallstents (diameter 3.5 (n = 3) an d 5 mm (n = 4)), which were implanted in seven coronary arteries of five pi gs. This 3-D geometry was used to calculate locally the curvature, while th e shear stress distribution was obtained by computational fluid dynamics. L ocal changes in shear stress were obtained at the entrance and exit of the stent for baseline (0.65 +/- 0.22 ml/s) and hyperemic flow (2.60 +/- 0.86 m l/s) conditions. Results. after stent implantation, the curvature increased by 121% at the e ntrance and by 100% at the exit of the stent, resulting in local changes in shear stress. In general, at the entrance of the stent local maxima in she ar stress were generated, while at the exit both local maxima and minima in shear stress were observed (p < 0.05). Additionally, the shear stress at t he entrance and exit of the stent were correlated with the local curvature (r: 0.30-0.84). Conclusion. Stent implantation changes 3-D vessel geometry in such a way th at regions with decreased and increased shear stress occur close to the ste nt edges. These changes might be related to the asymmetric patterns of in-s tent restenosis. (C) 2000 Elsevier Science Ltd. All rights reserved.