Prevention of Coagulum Formation With Simultaneous Charge Delivery in Radiofrequency Ablation: A Canine Model

Objectives: This study reports on a novel method to prevent coagulum formation by continuously delivering a negative charge to the catheter tip to repel negatively charged fibrinogen molecules during RF ablation.

Background: Radiofrequency (RF) ablation for cardiac arrhythmias is associated with a 70% incidence of coagulum formation on the catheter tip during ablation and a 10% incidence of thromboembolic events. Catheter tip thrombus can impede RF energy to the tissue, reducing efficacy and increasing procedure times.

Methods: A novel circuit was built to deliver a negative, fixed-offset, direct current-based charge using a 9-V battery, placed in parallel with an RF delivery unit during RF ablation. In in vivo canine experiments, standard ablation catheters were advanced into atria and ventricles under fluoroscopic guidance. The presence of thrombus with and without RF delivery was identified with intracardiac echocardiography.

Results: Scanning electron microscopy of the catheter tips showed clot coverage of the catheter tip to be 90% for noncharged catheters compared to 0% (p < 0.01) in negatively charged catheters. Volume of clot formed on the catheter tip decreased with increased amount of charge (140 ± 5.3 arbitrary units with no charge vs. 0 arbitrary units with a 100-μA current delivering negative charge, p < 0.01). Application of a negative charge did not affect the quality of the intracardiac electrogram or induce malignant ventricular arrhythmias.

Conclusions: Negative-charge delivery to ablation catheter tips and tissue during RF ablation is feasible and safe and can eliminate coagulum formation, potentially reducing thromboembolic complications.