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Page 2 of 7 Takamaru et al. Mini-invasive Surg 2022;6:15 https://dx.doi.org/10.20517/2574-1225.2021.120

for esophageal and colorectal ESD, was developed by Ono and Yamaguchi. The IT knife nano has a smaller
insulated tip, making it easier to handle the submucosal layer. The disk behind the insulated tip is also
smaller to reduce thermal damage to the muscle layer. Many studies on colorectal ESD using IT knife nano
[3-5]
have been reported .

CHARACTERISTICS OF IT KNIFE NANO
The IT knife nano can make incisions and resect using an electric current at the blade, one of the unique
features that separate it from the needle-type knives. A long blade of IT knife nano makes it possible to
resect the connected tissue, which is in contact with the submucosal tissue to be dissected. The IT knife
nano is considered to have more power for incision, resection, and coagulation than needle-type devices.
This is because the IT knife nano has a large amount of electric current at the blade compared to other
devices. However, needle-type devices concentrate the current energy at the top of the needle to increase the
current density. Therefore, the IT knife nano can resect a larger amount of submucosal layer tissue at once,
enabling a faster and more reliable detachment of the submucosal dissection.
[6]

STRUCTURE OF IT-KNIFE NANO
The IT-knife nano has an insulated tip of the blade. A small disk is equipped behind the insulated tip to
increase the resection efficiency. This disk makes it possible for the IT knife nano to resect the submucosal
layer using the back of the disk touching the connective tissue. However, it should be noted that damage to
the muscle layer by the burn effect of the disk may occur when the distance between the disk and the muscle
layer is close [Figure 1].

Therefore, we have used another version of the IT knife nano without a disk to resolve this issue. We used a
special made-to-order IT knife nano without a disk for lesions with a narrow submucosal layer caused by
fibrosis. This increases the electric current density and improves the resection ability of the blade. This
device also makes it easier to slip into the submucosal layer and approach the blade to the submucosal tissue
for resection, even if the surgical field is difficult due to fibrosis or other reasons. In addition, an insulated
tip without a disk is suitable for resection in a narrow working space of the submucosa. To use a special
made-to-order IT knife nano without a disk, requirements have to be met as follows: (1) expert
endoscopists perform many colorectal ESDs in a tertiary center; and (2) many IT knife nanos (normal type)
are used for colorectal ESD in the hospital. When a hospital matches these criteria, the hospital can order a
specially made IT knife nano from the industry.

TECHNIQUES OF IT KNIFE NANO
The IT knife nano is mainly designed to be pulled for resection, whereas other needle-type devices are based
on cutting in the pushing direction.

Therefore, when performing submucosal dissection using an IT knife nano, the knife should be moved from
the outside to the inside [Figure 2].

The detailed technique is as follows:

First, the edge of the submucosal tissue is visualized, and the knife blade hooked onto that edge. Then, the
scope is manipulated along the running of the muscle layer to resect the submucosal tissue. The moving
knife direction then should be aimed at the middle of the submucosal layer, which has been raised and
thickened by submucosal injection [Figure 3]. Next, submucosal dissection should be performed equally