Silicone vascular models for analysis of carotid artery stenting

Carotid artery stenting (CAS) is a minimally invasive surgical treatment for stenosis that is usually due to atherosclerotic plaque. Criteria to select an optimal stent for each clinical situation are lacking, however. Here we describe a surgical simulator that predicts vascular geometries after stenting using silicone rubber models of stenotic carotid arteries. Our objective was to develop the fabrication scheme of such vascular models. Herein, four CAS vascular models, or a soft plaque, two normal, and a hard one, were fabricated. By using rapid prototyping of 3D CT angiographic data, we first made a patient-specific wax models with geometries that matched the lumen of carotid artery. Next, we fabricated a plaque model that matches patient-identical geometries. Then, we produced the each part using silicone rubber with different mechanical properties. In order to match the mechanical properties of the vessel model, pre- and post-stent geometry were compared in vivo and vitro using digital angiography. Moreover, we compared the stiffness of the vessel model by the Young's modulus. We first evaluated the mechanical properties of the vessel, and then that of the plaque. As for the former, the relationship between the expansion ratio and the stiffness parameter β was formulated by curve-fitting. We evaluated the mechanical properties of each plaque. It was found that the Young's modulus were 0.015, 0.092, 0.137, 0.503 N/m², for the soft, normal (two cases), and hard plaque, respectively. The largest difference was about 34 times for the soft and hard one. We achieved to develop a novel fabrication scheme for the carotid artery with atherosclerotic plaque. The validated vascular model featured two distinct mechanical properties for the vessel and plaque. Such models may help surgeons develop criteria to optimize CAS in a patient-specific manner.