Model-based Force Estimation of a Steerable Ablation Catheter in the Presence of the Blood Flow

Catheter ablation (CA) is a well-established treatment for arrhythmia such as atrial fibrillation. Studies have shown that the rate of success of this procedure directly depends on the size, depth and shape of the lesions formed. Catheter tip-tissue contact force (CF) is known to be one of the key factors affecting lesion quality and therefore a major determinant of the outcome of the procedure. However, accurate knowledge of CF remains a major challenge due to the various complexities involved in the CA procedure. This paper presents the development of a kinetostatic model which can estimate CF in the presence of blood flow. The model, which is based on Euler-Bernoulli's beam theory to describe large deflection, is capable of reporting the tip contact force in real-time, where the effect of blood flow is approximated using the independence principle. The equation governing the static equilibrium of the catheter is formulated as a minimization problem and solved in MATLAB using the pseudo-inverse theorem, where the computational frequency of the force estimation was found to be 33.3 Hz. The proposed method is verified numerically using a finite element model, for various loading conditions, where the maximum relative error was found to be below 3%. Furthermore, a parametric study is conducted to investigate the effect of the blood flow on the catheter contact force estimation, for a catheter with various lengths, diameters, and bending stiffness.