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Page 6 of 20 Nakamura et al. Mini-invasive Surg 2022;6:50 https://dx.doi.org/10.20517/2574-1225.2022.38

Hot biopsy forceps
Hot biopsy forceps are used for hemostasis during gastric ESD. They feature larger cups than hemostatic
forceps; hence, they can capture more tissue and cauterize wider and deeper areas. This property is suitable
for ESD of the gastric body or cardia, where thick arteries often exist. An example of hot biopsy forceps is
the Radial Jaw 4 (Boston Scientific, Co., Ltd.).

Electrosurgical unit setting and device maneuver
Appropriate settings for an electrosurgical unit (ESU) and basic knowledge of electrosurgery have a
remarkable impact on the success of gastric ESD. Widely used electrosurgical units are VIO 200/300 or VIO
3 (ERBE, Co., Ltd.) and ESG-100/300 (Olympus, Co., Ltd.).

The ESU mode and device maneuverability (control of the contact area) must be adjusted according to the
different tissue conditions. The key tissue conditions are: (1) the rigidity of the tissue due to collagen fibers;
and (2) the presence of vessels. Rigid tissue must be incised with the cut mode (AUTO CUT, ENDO CUT,
etc.). Soft tissue can be cut in either cut mode or coagulation mode (FORCED COAG, SWIFT COAG, etc.).
Dissection of the soft tissue with cut mode avoids tissue shrinkage and maintains a clear-cutting plane while
dissection with coagulation mode prevents bleeding when blood vessels are contained. Bleeding interferes
with the visualization of the operation field and worsens electrical conduction, thus interrupting the ESD
procedure. Therefore, it is better to dissect the soft tissue containing blood vessels in coagulation mode to
avoid bleeding. Although thin vessels can be coagulated without bleeding by the ESD knives, when a thick
vessel is seen in the tissue, it is better to use hemostatic forceps with SOFT COAG mode to coagulate the
vessel. When the coagulation mode is used for dissection of the soft tissue without vessels, the contact area
between the tissue and the knife should be small enough to concentrate the electric current, achieve high
thermal energy, and render efficient tissue dissection. Conversely, to dissect highly vascularized soft tissue,
the contact area should be large enough to decrease the electrical current concentration and obtain an
efficient tissue coagulation effect. The size of the contact area is controlled by scope movement and device
maneuvers. With regard to the sequence of the ESD procedure, a mucosal incision is performed in the cut
mode because the mucosa contains the muscularis mucosae, which is a thin layer of tough, fibrous tissue.
Submucosal dissection is performed in the cut mode if there are no vessels in the submucosa or fibrous
tissue. Coagulation mode is used during submucosal dissection when vessels are present in the submucosa.

The settings of the cut mode (effect, duration, and interval) and coagulation mode (effect and wattage) are
adjusted according to the type of ESD device used. The ESU settings for gastric ESD in our facility are
shown in Tables 1-3.

ENDOSCOPIC PROCEDURE
Scope positioning and approach
For a longitudinal location, a lesion in the antrum is generally approached from the oral side with the
forward view, while a lesion in the corpus is approached from the anal side with the retroflex view because
gravity in the stomach moves toward the fornix and lifts a dissected specimen up in these positions
[Figure 4].

For a circumferential location, the difficulty of the ESD procedure can be assumed based on the direction of
gravity [Figure 5]. The direction of gravity is distinguished by the presence of fluid. The dissection
procedure for a lesion on the anti-gravity side is uncomplicated because the dissected specimen is
spontaneously flipped up by gravity [Figure 5A]. For a lesion on the ipsilateral side of gravity, it is better to
start a mucosal incision from the gravity side because the tension of mucosa from the anti-gravity side helps