Development of computer-based simulator for catheter navigation in blood vessels (2nd report, evaluation of torquability of guidewire)

We have developed catheter simulation system in blood vessels for surgical planning and intra-operative assistance. In this study, we evaluated the torquability of the guidewire model for the simulation system. The model of the guidewire is constructed with viscoelastic springs and segments as the dynamic deformation of a flexible structure. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness and friction of the vessel wall. Using these models, the trajectory of the guidewire tip was calculated when the proximal part of the guidewire model was twisted at a constant speed. When the friction coefficient between the guidewire and the vessel is large, the guidewire tip vibrates. When the guidewire is twisted, there is a lag before the guidewire tip starts rotating and friction obstructs this rotation. Besides the friction coefficient, the shape of the blood vessel also affects the motion of the guidewire tip. When the guidewire becomes stirrer, the torquability of guidewire tip increases. This simulator would be useful for the analysis of the structure of the guidewire and may help guide the design of new guidewire.