In vivo study on the feasibility of a single needle electrode to perform irreversible electroporation (IRE) in hepatic tissue

Objective: Irreversible electroporation (IRE) is an alternative to thermal tissue ablation in situ. Current irreversible electroporation (IRE) systems requires cardiac synchronization and paralytics, and ≥2 electrodes to be placed using an open approach. We sought do develop a single needle high-frequency irreversible electroporation (H-FIRE) system, used in conjunction with external dispersive electrodes (grounding pads), to perform hepatic ablations in vivo. Methods: Swine were anesthetized, a midline laparotomy performed, and the liver exposed. An H-FIRE electrode was inserted into the parenchyma and 2 dispersive electrodes were placed on the hind limbs. In the absence of paralytics or cardiac synchronization H-FIRE pulses (100 or 300) were delivered (2250 V, pulse length 0.5, 1, or 2 μs) for 50 or 100 μs (on-time). 6 Hrs later the animal was euthanized and tissue resected/analyzed. Results: 16 independent H-FIREs were performed in 3 separate animals. No ECG abnormalities or changes in vital signs occurred during H-FIRE. Minor twitching of the rectus abdominis and muscles near the dispersive electrodes were recorded during H-FIRE. Average ablation diameter was 10.50 ± 0.35 mm, and histological analysis demonstrated absence of significant damage to vascular and biliary structures concomitant with a lack of coagulative necrosis. Immunohistochemical analysis demonstrated cell death was predominantly apoptotic, with minor necrotic cell death adjacent to the electrode. Conclusion: H-FIRE can be safely delivered via a single electrode to create reproducible hepatic ablations in vivo, while preserving underlying hepatic architecture. Optimizing pulse delivery should increase ablation size and reproducibility, and a single electrode system opens the possibility for development toward laparoscopic use.