Estimating contact force for steerable ablation catheters based on shape analysis

Cardiac ablation using flexible catheters is a common interventional procedure for treating cardiac arrhythmia. This procedure is performed under image guidance and the contact force between the ablation tip and the heart tissue is one of the factors that greatly impacts the efficacy of the ablation procedure. This paper investigates the feasibility of estimating the force that the catheter tip exerts on the heart tissue by monitoring the changes in the shape of the deflectable distal shaft of the catheter (henceforth called the “deflectable shaft” or the “shaft” of the catheter). It is shown that variations in the shaft curvature provide information about how much force the catheter tip is exerting at its point of contact. Consequently, an index is defined for determining the range of contact forces based on the shaft curvature. Experimental results show that the defined index can correctly detect the range of applied contact forces in more than 80% of the cases. This study proves that the flexibility of the deflectable shaft provides a means of estimating contact forces exerted by the catheter tip.