EP radiofrequency generators: Significant offsets between selected and delivered power?

Abstract

Introduction: For radiofrequency (RF) ablation, the EP Shuttle^® (Stockert GmbH, Freiburg, Germany), Ampere^® (St. Jude Medical, St. Paul, MN, USA), and SmartAblate^® (Biosense Webster, Diamond Bar, CA, USA) generator models are most frequently used in clinical practice. The aim of this study was to assess the correlation between selected and delivered RF power for different generators.

Methods and results: In an experimental setup, ablation catheters were connected to the EP Shuttle^® , Ampere^® , and SmartAblate^® generators. The power delivered by the generators was measured using a current converter and an oscilloscope. The selected power displayed on the generator was compared to the actually delivered power measured by the experimental setup (n = 800 measurements). The offsets between selected and delivered power increased significantly with impedance (EP Shuttle^® ). For example, at a selected power of 30 W, the delivered power was 40.3 W (EP Shuttle^® ), 30.1 W (Ampere^® ), and 28.1 W (SmartAblate^® ) at an impedance of 200 Ω. In addition, ablation lesions (n = 80) were created in ex vivo porcine cardiac muscle preparations. The resulting ablation lesion size was calculated in caliper measurements. When the EP Shuttle^® generator was operated at 200 Ω, the resulting lesion size was significantly larger than at 100 Ω. There were no significant offsets between power delivery and lesion size when using the Ampere^® or SmartAblate^® generators.

Conclusions: The Ampere^® and SmartAblate^® generator models deliver accurate power as selected by the user. The power delivered by the EP Shuttle^® generator exceeds the selected power by up to 40% depending on impedance. The findings were confirmed in ex vivo porcine heart experiments and should be considered in clinical practice.

Keywords: accuracy; catheter ablation; generator; lesion; radiofrequency.