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2.3 MECHANICAL ENGINEERING
As in-stent restenosis following coronary stent deployment has been strongly linked with stent-induced arterial injury and altered vessel hemodynamics, the sequential numerical analysis of the mechanical and hemodynamic impact of stent deployment within a coronary artery is likely to provide an excellent indication of coronary stent performance. Despite this observation, very few numerical studies have considered both the mechanical and hemodynamic impact of stent deployment. In light of this observation, the aim of this research is to develop a robust numerical methodology for investigating the performance of balloon-expandable coronary stents in terms of their mechanical and hemodynamic impact within a coronary artery. The proposed methodology is divided into two stages. In the first stage, a numerical model of the stent is generated and a computational structural analysis is carried out to simulate its deployment within a coronary artery. In the second stage, the results of the structural analysis are used to generate a realistic model of the stented coronary lumen and a computational fluid dynamics analysis is carried out to simulate pulsatile blood flow within a coronary artery. Following the completion of the analyses, the mechanical impact of the stent is evaluated in terms of the stress distribution predicted within the artery whilst the hemodynamic impact of the stent is evaluated in terms of the wall shear stress distribution predicted upon the luminal surface of the artery. In order to demonstrate its application, the proposed numerical methodology was applied to six generic stents. Comparing the predicted performance of the generic stents revealed that strut thickness is likely to have a significant influence upon both the mechanical and hemodynamic impact of coronary stent deployment. Additionally, comparing the predicted performance of three of the investigated stents to the clinical performance of three comparable commercial stents, as reported in two large-scale clinical trials, revealed that that the proposed numerical methodology successfully identified the stents that resulted in higher rates of angiographic in-stent restenosis, late lumen loss and target-vessel revascularisation at short-term follow-up. In light of the conflicting requirements of coronary stent design, the proposed numerical methodology should prove useful in the design and optimisation of future coronary stents.
Martin, D. M. (2013) Sequential structural and fluid dynamics analysis of balloon-expandable coronary stents. Doctoral Thesis, Dublin Institute of Technology. doi:10.21427/D7G31Z