Experimental High-Frequency Irreversible Electroporation Using a Single-Needle Delivery Approach for Nonthermal Pancreatic Ablation In Vivo

Purpose: To investigate the feasibility of single-needle high-frequency irreversible electroporation (SN-HFIRE) to create reproducible tissue ablations in an in vivo pancreatic swine model. Materials and Methods: SN-HFIRE was performed in swine pancreas in vivo in the absence of intraoperative paralytics or cardiac synchronization using 3 different voltage waveforms (1-5-1, 2-5-2, and 5-5-5 [on-off-on times (mu s)], n = 6/setting) with a total energized time of 100 mu s per burst. At necropsy, ablation size/shape was determined. Immunohistochemistry was performed to quantify apoptosis using an anticleaved caspase-3 antibody. A numerical model was developed to determine lethal thresholds for each waveform in pancreas. Results: Mean tissue ablation time was 5.0 +/- 0.2 minutes, and no cardiac abnormalities or muscle twitch was detected. Mean ablation area significantly increased with increasing pulse width (41.0 +/- 5.1 mm(2) [range 32-66 mm(2)] vs 44 +/- 2.1 mm(2) [range 38-56 mm(2)] vs 85.0 +/- 7.0 mm(2) [range 63-155 mm(2)]; 1-5-1, 2-5-2, 5-5-5, respectively; p < 0.0002 5-5-5 vs 1-5-1 and 2-5-2). The majority of the ablation zone did not stain positive for cleaved caspase-3 (6.1 2.8% [range 1.8-9.1%], 8.8 1.3% [range 5.5-14.0%], and 11.0 +/- 1.4% [range 7.1-14.2%] cleaved caspase-3 positive 1-5-1, 2-5-2, 5-5-5, respectively), with significantly more positive staining at the 5-5-5 pulse setting compared with 1-5-1 (p < 0.03). Numerical modeling determined a lethal, threshold of 1114 +/- 123 V/cm (1-5-1 waveform), 1039 +/- 103 V/cm (2-5-2 waveform), and 693 +/- 81 V/cm (5-5-5 waveform), Conclusions: SN-HFIRE induces rapid, predictable ablations in pancreatic tissue in vivo without the need for intraoperative paralytics or cardiac synchronization.