Model-based Force Estimation for Intra-cardiac Catheters

The objectives of this paper are twofold: first, presenting an efficient quasi-static model for intracardiac catheters, and second, proposing a real-time approach for the estimation of the force at the tip using the proposed model. The force estimation approach has the potential to be used in conjunction with previously developed pose sensing technologies to provide a sense of the forces applied by the catheter to the heart tissue in cardiac ablation procedures. The catheter is modeled as a planar elastica, consisting of consecutive circular curves. The parameters of the model are obtained through experiments, leading to a precise description of the shape of the catheter for the given external forces. The approach incorporates modeling of the compound system (distal shaft and catheter body) with inhomogeneous mechanical properties. The force estimation approach is based on the pose measurement of the catheter tip along with the identified parameters of the catheter model. As a result of the low dimensionality of the proposed quasi-static model, the inverse problem can be efficiently solved for the estimation of the external forces. The experiments performed using electromagnetic sensors verify the feasibility of the proposed scheme in medical applications.