Stress distribution on a cobalt-chromium stent placed into an artery with and without atherosclerotic plaque

• Κύριος συγγραφέας: Στρατάκος, Στάθης
• Άλλοι συγγραφείς: Stratakos, Stathis
• Γλώσσα: English
• Έκδοση: 2020
• Θέματα: Finite elment analysis; Computational structural mechanics; Simulation; Iliac artery; Computed tomography; Critical limb ischemia; Balloon expandable stent; Fatigue; Reverse engineering; Stent mechanics; Ανάλυση με πεπερασμένα στοιχεία; Υπολογιστική μηχανική; Προσομοίωση; Λαγόνια αρτηρία; Τομογραφία; Κρίσιμη ισχαιμία άκρων; Stent επεκτάσιμο με μπαλόνι; Κόπωση; Ανάστροδη μηχανική; Μηχανική stent

Cardiovascular diseases are a group of disorders of the heart and blood vessels. Globally, CVDs are the leading cause of death and serious illness, taking an estimated 17.9 million lives each year. To put things in perspective, this figure is interpreted into a total of 31% of all deaths worldwide. The treatment of coronary and peripheral artery disease using metallic stents has been one of the most revolutionary and most rapidly adopted medical interventions of our time. In the present study, a brief reference is made to vascular endoprosthesis - stents and their evolution. Next, the range of materials used, and their geometric characteristics are highlighted, in combination with the influence of these parameters on the behavior of the stent itself as well as the artery. Then, the stent of Rontis corporation is constructed using as a prototype the units provided by the company, while in collaboration with members from the R&D department of the company, its mechanical properties are verified through simulation in finite element analysis. Subsequently, the behavior of the stent during its compression and expansion is simulated and investigated, changing certain parameters, in order to validate the constructed geometry. At the same time, a case of critical limb ischemia is selected from a patient, and the three-dimensional geometric model at a curved point of the iliac artery in which atherosclerotic plaque has developed is extracted from the tomography of the case. Consequently, after processing the 3D model, part of it is inserted assembled together with the stent into a finite element program and the process of its expansion in a quasi-static analysis is simulated. Finally, the fatigue cycles needed to occur until the stent failure were calculated under cyclic loading which is caused by the alteration between systolic and diastolic pressure.