Goal:  Maintaining a constant contact force (CF) of an ablation catheter during cardiac catheter ablation therapy is clinically challenging due to inherent myocardial motion, often resulting in poor ablation of arrhythmogenic substrates. To enable a prescribed contact force to be applied during ablation, a catheter contact force controller (CCFC) was developed.  Methods:  The system includes a hand-held device attached to a commercial catheter and steerable sheath. A compact linear motor assembly attaches to an ablation catheter and autonomously controls its relative position within the shaft of the steerable sheath. A closed-loop control system is implemented within embedded electronics to enable real-time catheter-tissue contact force control. To evaluate the performance of the CCFC, a linear motion phantom was used to impose a series of physiological CF profiles; lesion CF was controlled at prescribed levels ranging from 15 to 40 g.  Results:  For a prescribed CF of 25 g, the CCFC was able to regulate the CF with a root mean squared error of 3.7 ± 0.7 g. The ability of the CCFC to retract the catheter upon sudden changes in tissue motion, which may have caused tissue damage, was also demonstrated. Finally, the device was able to regulate the CF for a predetermined amount of time according to a force-time integral model.  Conclusion:  The developed CCFC is capable of regulating catheter-tissue CF in a laboratory setting that mimics clinical ablation therapy.  Significance:  Catheter-tissue CF control promises to improve the precision and success of ablation lesion delivery.
['Daniel Gelman', 'Allan C. Skanes', 'Mohammad Ali Tavallaei', 'Maria Drangova']
Design and Evaluation of a Catheter Contact-Force Controller for Cardiac Ablation Therapy