Irreversible electroporation of the liver: is there a safe limit to the ablation volume?

Abstract

Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around 40% of mouse liver. One group consisted in 55 athymicnude, in which a tumor from the KM12C cell line was grown and the other thirty-two C57-Bl6 nontumoral mice. Both groups were subsequently divided into subsets according to the delivered field strength (1000V/cm, 2000V/cm) and whether or not they received anti-hyperkalemia therapy. Early mortality (less than 24hours post-IRE) in the 2000V/cm group was observed and revealed considerably higher mean potassium levels. In contrast, the animals subjected to a 2000V/cm field treated with the anti-hyperkalemia therapy had higher survival rates (OR=0.1, 95%CI=0.02–0.32, p<0.001). Early mortality also depended on the electric field magnitude of the IRE protocol, as mice given 1000V/cm survived longer than those given 2000V/cm (OR=4.7, 95%CI=1.8–11.8, p=0.001). Our findings suggest that ionic disturbances, mainly due to potassium alterations, should be warned and envisioned when large volume ablations are performed by IRE.