Pulsed Field Ablation Therapy Parameters: Enhancing Lesion Depth While Reducing Musculoskeletal Stimulation and Thermal Response in an Irrigated Tip Catheter: A Comprehensive Study Using In Silico, In Vitro, and In Vivo Models.

backgroundPulsed field ablation therapies need to be optimized to maximize lesion depth while mitigating heat and musculoskeletal stimulation. We describe the adjustment of biphasic pulsed field ablation parameters for an irrigated tip catheter.

methodsExperimental models all used an 8F, flexible-tip, irrigated ablation catheter. Computer simulation models were designed to assess the effects of bipolar versus monopolar applications. A vegetal (potato) model was used to assess the effects of voltage, pulse width, and number of pulses per burst on lesion depth. In-vitro testing on bovine cardiac muscle was performed with temperature sensors at the surface and 3 and 7 mm beneath the surface to measure temperature rises. Finally, an in vivo canine model was used to assess for musculoskeletal stimulation caused by the pulsed field ablation therapies established with the vegetal/in vitro testing.

resultsMonopolar delivery consistently delivered more tissue depth than bipolar configurations. Adjustments from n to n+1.0 µs and increasing pulses per burst from 50 to 250 increased lesion depth but also increased musculoskeletal stimulation. The optimized burst count was 5 R-wave-gated bursts over 4 to 9 seconds. The optimized therapy had a minimal observed depth of >5 mm and minimized musculoskeletal stimulation. Final selected therapies did create temperature rises, which were completely offset by irrigation rates of 7 to 13 mL/min.

conclusionsPulse width and number of pulses per burst are important contributors to lesion depth, musculoskeletal stimulation, and incident heating. Even small adjustments in these parameters can alter lesion depth, muscle stimulation, and thermal effects, which will differentiate optimal from suboptimal pulsed field ablation.