2 Therefore, it is necessary to be able to predict the behavior (e.g. reaction forces and changes in the mechanical factors such as stress and strain fields) of both the device and the host tissue prior to the procedure, to minimize the negative outcomes and reduce the procedural cost. Currently, biomechanics involved in the PMTA procedure has not been well studied. In our previous work [16, 17], we have studied the deployment of proximal anchor of the PTMA device using computational models to predict the interaction between the human/porcine derived material CS vessel models and the stent. We observed that stiffer stent material tends to have a better safety factor when deployed in a relatively softer tissue (porcine). Although human tissue offered an adequate radial forces, another concern arises that is high stresses on the vessel wall may induce a vascular injury. In this study, we attempted to alter the stent design to reduce radial interactive forces. The approach includes maintain the same material properties of the stent and varying the design parameters, e.g. the strut thickness. Two stents models with different strut thickness values were developed. The results from these models include peak stresses and strains, interaction forces (shear and normal) of the CS wall and the stent, as well as the device fatigue life and safety factor were compared to the original design, and differences between these design can provide insights into the stent designs that may help to reduce future device failure in the PTMA intervention. Figure 1 Illustration of a Monarch™ PTMA being deployed into the CS vessel, which is adjacent to the posterior mitral annulus. ANT - anterior mitral leaflet. PML - posterior mitral leaflet. GCV - great cardiac vein. METHODS/MATERIALS Stent models. Typical mechanical properties of superelastic Nitinol material are illustrated in Fig. 2a, and the material parameters used in this study are listed in Table 1. Three stent designs were developed, 1) the original design with a stent strut thickness of 0.30 mm, 2) modified stents with a thickness of 0.23 mm and 3) thickness of 0.18 mm, denoted as, Original, Mod1 and Mod2, respectively. Fig. 3 illustrates the stent in the undeformed and deformed configurations. Details of design parameters of these stent models are listed in Table 2. The original PTMA device is composed of two and twelve strut cells in the axial and circumferential directions, respectively.
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