Background: Single pulse irreversible electroporation (IRE) is a non-thermal method used for cardiac ablation, in which a direct current is delivered between a catheter and a skin patch. Catheter polarity influences the direction of the current through the cardiac cells. Theoretically, this will not influence lesion depth, since cells are insensitive for current direction. However, some studies suggest that polarity does influence lesion size due to electrolytic effects, beyond the region of electroporation.
Objective: To investigate the influence of catheter polarity on lesion size with IRE.
Methods: Epicardial ablation was performed in 8 pigs using a custom suction device with a linear electrode of 35 x 6 mm. Cathodal and anodal IRE-pulses were delivered at the left ventricle (50J and 100J) and the right ventricle (30J). After three weeks the animals were euthanized, and the lesions were sliced and stained. Lesion depth was measured by a blinded observer. In case of a transmural lesion, the lesion thickness (decreases over time) was assumed to be the thickness of the adjacent healthy myocardium.
Results: 48 lesions (464 slides) were analyzed. No significant difference in lesion depth was found between cathodal and anodal pulses of 30J and 50J. With 100J, lesions after anodal pulses were significantly deeper than after cathodal pulses (p=0.012). This may be explained by a different number of sections that showed transmural lesions.
Conclusion: Overall results of this study suggest that IRE-pulses with anodal electrode polarity create deeper lesions, possible due to electrolytic effects. The exact mechanism remains to be elucidated.