Evaluation of variable inter-pulse delay and timing on pulsed field ablation lesion characteristics

Irreversible electroporation with pulsed-field ablation (PFA) represents a promising modality via myocyte-selective treatment of arrhythmias. However, aside from voltage, a thorough evaluation of PFA output parameters on lesion characteristics has not been performed.

To demonstrate the impact of timing cycle attributes on PFA lesion characteristics using an established in vitro electroporation model.

Russet potato slabs underwent unipolar PFA using a 3.5-mm electrode catheter connected to a programmable PFA generator. PFA waveforms were delivered with a train ranging from 1 to 3 biphasic pulses, 1 to 50 cycles, frequency of 50 kHz, inter-pulse delay of 200 to 1310 ms, and with repeated applications using variable inter-application pauses from 5 to 20 s. Experiments were repeated with varying voltage outputs. The slabs were sliced, stained, and measured.

Increasing number of cycles and number of PFA applications were associated with larger lesions but reached a plateau effect despite increased total energy delivered. There was a linear relationship between increasing inter-pulse delay and depth. There was no change in lesion size with application period.

Increasing the inter-pulse delay of pulse sequences created deeper lesions despite total energy remaining constant and achieved similar depths compared to pulses that used more cycles and greater number of applications. Modulating inter-pulse delay may be useful for controlling lesion depth without increasing total application energy delivery, which may reduce risks associated with high energy PFA pulses. Further research is required to correlate these in vitro findings with in vivo results and clinical outcomes.