Structural and fluid dynamic assessment of stenting procedures for coronary bifurcations

Despite their wide success and acceptance, stenting procedures are still an open problem in the clinical field, especially in complex vascular tracts such as coronary bifurcations. These regions are a very atheroprone environment because of a peculiar hemodynamic field characterized by recirculation and stagnation zones. Moreover, the anatomical complexity of bifurcated lesions and the technical difficulties during stent deployments concur in lower procedural success rates and higher risk of post-stenting clinical problems, such as sub-acute stent thrombosis and in-stent restenosis, respect to common linear lesions. Different options and interventional strategies have been proposed but, currently, an optimal solution has not been identified, yet. In this light, the main objective of this PhD thesis is the development of both structural and fluid dynamic engineering methods able to better investigate the biomechanical effect of stenting procedures in coronary bifurcations. After describing the main modelling techniques developed by means of finite element analyses, computational fluid dynamics or digital particle image velocimetry, several case studies are presented to examine and compare the most adopted stenting procedures and the currently available stents for coronary bifurcations. Two main findings arise from the models here presented: i) the importance of new dedicated devices specific for bifurcations and ii) the worse biomechanical influence of double-stenting procedures respect to single-stenting procedures are the main findings proposed in this thesis. Particular attention is finally dedicated to the implementation of image-based patient specific models able to replicate real interventions. In summary, the results obtained show that such models may provide useful insights for both the industry to improve the commercially available devices and for the clinical world to enhance the current stenting procedures and facilitate the interventional planning.