Time-Dependent Impact of Irreversible Electroporation on Pathology and Ablation Size in the Porcine Liver: A 24-Hour Experimental Study
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Irreversible electroporation causes cell death through low frequency, high voltage electrical pulses and is increasingly used to treat non-resectable cancers. A recent systematic review revealed that tissue damage through irreversible electroporation is time-dependent, but the impact of time on the ablation zone size remains unknown. Irreversible electroporation ablations were performed hourly during 24 consecutive hours in the peripheral liver of 2 anaesthetized domestic pigs using clinical treatment settings. Immediately after the 24th ablation, the livers were harvested and examined for tissue response in time based on macroscopic and microscopic pathology. The impact of time on these outcomes was assessed with Spearman rank correlation test. Ablation zones were sharply demarcated as early as 1 hour after treatment. During 24 hours, the ablation zones showed a significant increase in diameter (rs = 0.493, P = .014) and total surface (rs = 0.499, P = .013), whereas the impact of time on the homogeneous ablated area was not significant (rs = 0.172, P = .421). Therefore, the increase in size could mainly be attributed to an increase in the transition zone. Microscopically, the ablation zones showed progression in cell death and inflammation. This study assessed the dynamics of irreversible electroporation on the porcine liver during 24 consecutive hours and found that the pathological response (ie, cell death/inflammation), and ablation size continue to develop for at least 24 hours. Consequently, future studies on irreversible electroporation should prolong their observation period.