To treat atrial fibrillation (AFib), radiofrequency ablation is usually implemented with a cardiac catheter to block abnormal electrical signals from pulmonary veins. However, it is challenging to manipulate a passive catheter. In addition, the radiation exposure to patients under fluoroscopic guidance has been a concern. To address these two major issues, this work presents the development of a steerable and MRI-compatible cardiac catheter by using shape memory alloy (SMA) as an alternative interventional tool for AFib. The developed cardiac catheter is comprised of a passive and flexible tubing and a steerable tip. The tip is composed of multiple bending modules and each module is actuated by a pair of antagonistic SMA wires. To improve the MRI-compatibility of SMA actuators, the electric current required for SMA actuation is significantly reduced by developing a technique of conductive heating actuation. In this paper, the design and fabrication of the cardiac catheter are presented, followed by modeling the SMA bending module. The working performance of the SMA bending module is experimentally studied. In the end, a proof-of-concept demonstration of the cardiac catheter is performed in an explanted heart.
Sheng et al. (2018) studied this question.