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Mucosal preparation
Poor mucosal visibility, caused by mucus or bubbles, can interfere with proper lesion recognition and
precise device movement during the procedure. Moreover, when complications such as perforation or
bleeding occur, inadequate mucosal preparation makes their management difficult. In our institution, a
mixture comprised of 20,000 units of pronase, 1 g of sodium bicarbonate, 20 mg of dimethylpolysiloxane,
and 80 mL of water is administered before ESD.

Sedation
In Japanese practice, most gastric ESD procedures are performed in the endoscopy unit under deep sedation
using a combination of intravenous benzodiazepines, i.e. midazolam, diazepam, flunitrazepam, etc., and
analgesics, i.e. pethidine, pentazocine, etc. This is because ESD usually develops from EMR, and the same
setting can be continued. In the case of patients being restless, haloperidol drip infusion or continuous
infusion of dexmedetomidine is useful. When an extremely long (> 3 h) procedure is expected or for lesions
in difficult locations, propofol sedation or general anesthesia could be considered. With deeper sedation or
under general anesthesia, a patient’s movement disappears, and an operator can concentrate on the
procedure.

DEVICES
Endo-knife
There are several types of knives available for gastric ESD, and they are mainly grouped into needle-type,
partially insulated-type, and scissor-type knives [Figure 1].

Needle-type knife
A needle-type knife can be used in all situations in ESD procedures, that is, mucosal marking, mucosal
incision, and submucosal dissection. The needle tip allows accurate and pin-point tissue dissection and is
especially useful for dissecting fibrosis in the submucosa. Although the needle tip enables the tissue to be
incised in any direction, the chance of perforation is higher than that of other knives. Therefore, precise
adjustment of the depth and direction of movement is required for a safe operation. Recently, most needle-
type knives have been equipped with a water-jet function, which allows submucosal injection by knives.
This increases safety and reduces procedural time.

In general, the direction of movement for mucosal incision and submucosal dissection with a needle knife-
type device is from the center to the periphery and from the near side to the far side [Figure 2].

Representative needle knife-type devices are the Dual Knife (Olympus, Co., Ltd.), Flush Knife (Fujifilm, Co.,
Ltd.), Splash M-Knife (Pentax, Co., Ltd.), Hybrid Knife (ERBE, Co., Ltd.), and ORISE ProKnife (Boston
Scientific, Co., Ltd.).

Partially insulated-type knife
A partially insulated-type knife has a small ceramic ball at the tip of the needle to avoid electrical cautery
conduction. The ceramic tip prevents current transmission from the tip of the needle to the deep tissues,
thus reducing the risk of unintentional perforation or bleeding. Because the non-insulated tip cannot dissect
the tissue, the proximal metal part is used for tissue dissection. The characteristic structure of the insulated-
type knife requires the use of a needle-type knife for marking and pre-cutting. In general, the direction of
movement for mucosal incision and submucosal dissection with an insulated-type knife is contrary to that
of the needle-type knife: from the periphery to the center, and from the far side to the near side [Figure 3].