A novel angiography-based computational modelling for assessing the dynamic stress and quantitative fatigue fracture risk of the coronary stents immediately after implantation: Effects of stent materials, designs and target vessel motions

Abstract

Fluctuating stress on the implanted coronary stents within cardiac cycle is an important mechanism of fatigue fracture, which is associated with in-stent restenosis and stent thrombosis. We developed a novel computational modelling to calculate the dynamic stress of stents based on the time sequence angiography immediately after treatment. Two groups of patient-specific cases (one same stent design treated in 4 different coronary arteries and one same artery actually/virtually implanted one stent with 3 different designs) were performed the dynamic stress analysis by this computational modelling and subsequently assessed the fatigue fracture risk by Goodman method. The motion of target arteries significantly impacts on distribution of the stress and the risk of stent fracture, particularly in the site of hinge motion. Both the location of stent stress concentration in the obtuse marginal artery and the “unsafe” region in the inverse fatigue safety factor contour co-registered with the position of complete transverse fracture 13 months later after implantation. Three stents with different designs had the same location of highest stress concentration at the hinge motion site of the actually/virtually treated artery. Higher strength stent materials are significantly lower the risk of stent fracture rather than stent designs. This new computational modelling might be a useful tool in assessment of fracture risk of the implanted stent and in optimizing new design of dedicated stent treated specific coronary arteries and mechanical properties in vivo of bioresorbable scaffold during degradation process.

Keywords

• Coronary angiography
• Dynamic stress
• Superficial wall strain
• Fatigue analysis
• Cardiac cycle
• Cardiovascular biomechanics