Radiofrequency ablation using a novel insulated-tip ablation catheter can create uniform lesions comparable in size to conventional irrigated ablation catheters while using a fraction of the energy and irrigation

Abstract

Introduction: During radiofrequency ablation (RFA) using conventional RFA catheters (RFC), ~90% of the energy dissipates into the bloodstream/surrounding tissue. We hypothesized that a novel insulated-tip ablation catheter (SMT) capable of blocking the radiofrequency path may focus most of the energy into the targeted tissue while utilizing reduced power and irrigation.

Methods: This study evaluated the outcomes of RFA using SMT versus an RFC in silico, ex vivo, and in vivo. Radiofrequency applications were delivered over porcine myocardium (ex vivo) and porcine thigh muscle preparations superfused with heparinized blood (in vivo). Altogether, 274 radiofrequency applications were delivered using SMT (4-15 W, 2 or 20 ml/min) and 74 applications using RFC (30 W, 30 ml/min).

Results: RFA using SMT proved capable of directing 66.8% of the radiofrequency energy into the targeted tissue. Accordingly, low power-low irrigation RFA using SMT (8-12 W, 2 ml/min) yielded lesion sizes comparable with RFC, whereas high power-high irrigation (15 W, 20 ml/min) RFA with SMT yielded lesions larger than RFC (p < .05). Although SMT was associated with greater impedance drops ex vivo and in vivo, ablation using RFC was associated with increased charring/steam pop/tissue cavitation (p < .05). Lastly, lesions created with SMT were more homogeneous than RFC (p < .001).

Conclusion: Low power-low irrigation (8-12 W, 2 ml/min) RFA using the novel SMT ablation catheter can create more uniform, but comparable-sized lesions as RFC with reduced charring/steam pop/tissue cavitation. High power-high irrigation (15 W, 20 ml/min) RFA with SMT yields lesions larger than RFC.

Keywords: SMT; catheter ablation; power; radiofrequency; steam pop.