Post written by Kenjiro Yamamoto, MD, from the Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan. 

In this study, we conducted animal experiments to evaluate incision force and coagulation effect in various settings of the endoCUT mode with the VIO (Erbe, Tübingen, Germany) series. We determined the optimal electrosurgical unit (ESU) settings for endoscopic papillectomy (EP).

We identified the ESU-related factors associated with tissue invasiveness based on various verification methods in a large number of experiments, enabling EP to be a less-invasive procedure.

The endoCUT-I mode is set with a longer initial cutting phase and a longer cutting phase in duration than the endoCUT-Q mode. Duration setting provides a coagulation effect on its own. Effect setting should be set to 1 for EP, which does not generate coagulation voltage because duration setting also provides a coagulation effect through the initial cutting phase.

Overall, based on the results of this study, we concluded that the optimal VIO settings for ideal EP, namely “VIO EP mode,” is endoCUT-I mode with effect 1, duration 4, and interval 1. We believe this optimal ESU setting provides ideal EP resection.

We hope the findings from this study on ESU will be of help to therapeutic endoscopists in all fields.

The principle of incision. Passing a low voltage of 200 Vp or more and a continuous sinusoidal current between the electrode and the tissue generates Joule heat (A), which dehydrates and dries the tissue, creating a space between the electrode and the tissue (B). This is followed by generation of a small aerial discharge accompanied by a few small sparks (C). Through the sparks, the current is concentrated at a single point and flows into the tissue, resulting in extremely high current density (D). The water inside the cell then boils instantly (bumping) (E), causing the cell membrane to rupture (phreatic explosion) and the tissue to be cut (F). The current further spreads to the surrounding area, and the generated Joule heat, which is kept below the boiling point, causes coagulation of the surrounding tissue (G).

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