Video 1
The novel versatile knife (Optimos knife) used in this study. The tip of the knife can be rotated fully and smoothly by controlling the button on the handle. The transparent sheath of the knife is suitable for attaining the best view during the procedure. The 1.9-mm-wide and 2.5-mm-long anchor-shaped tip allows the performance of several steps of ESD including marking, circumferential incision and cutting, and dissection and vessel coagulation. The outer sheath allows additional submucosal injection and saline irrigation without changing the device.
Video 3
Endoscopic submucosal dissection procedures in the animal model. All markings on the target mucosa were circumferentially made with the tip of the Optimos knife, using a soft coagulation mode. Using a 23-gauge needle, the mixed solution was repeatedly injected into the submucosal layer until the target mucosa was totally raised. In the Optimos knife group, mucosal incision was started at the proximal end of the target lesion and extended around the markings using an endocut mode to almost complete the mucosal incision. Submucosal dissection was gradually carried out, using the forced coagulation mode. Finally, the distal remnant mucosal area was cut with the hooking method. If bleeding occurs during dissection, saline irrigation can be performed for securing a clear view using the water injection system of the Optimos knife. The knife in a forced coagulation mode is sufficient to coagulate the small vessels of a ramified vascular network. The water injection system was also used to keep enough fluid in the submucosa for continuous submucosal dissection. In the combination knives group, three conventional knives (the IT-2 knife, the Hook Knife, and the Dual knife) were used according to the same steps as the Optimos knife group.
Fig. 1The novel versatile knife (Optimos knife; Taewoong Medical) used in this study. (A) The Optimos knife has a 1.9-mm-wide and 2.5-mm-long anchor-shaped tip, which can be smoothly and fully rotated by controlling the dial on the handle of the knife. (B) The outer sheath can perform the water injection function. (C) The handle of the knife.
Fig. 2Endoscopic submucosal dissection (ESD) procedures in the animal model. (A) Markings were made with the tip of the Optimos knife (Taewoong Medical) in the soft coagulation mode. (B) The mixed solution was repeatedly injected into the submucosal layer. (C-E) The tip of the Optimos knife was used to make the incision along the markings, using the endocut mode. (F-J) Submucosal dissection was carried out using the forced coagulation mode. The vessel was coagulated by the hooking method using the soft coagulation mode and cut using the endocut mode. (K, L) The distal remnant mucosal area was cut with the hooking method. (M-O) The knife can coagulate the small vessels of a ramified vascular network in a forced coagulation mode. (P, Q) The water injection system was used to keep enough fluid in the submucosa for continuous submucosal dissection. (R, S) The Coagrasper forceps were used to control major bleeding from large vessels, using the soft coagulation mode. (T) The post-ESD ulcers were shown to prevent bleeding afterward. (U-X) Three conventional knives (the IT-2, the Hook Knife, and the Dual knife) were used for ESD in the combination knives group.
Fig. 3Part of the stomach harvested from the second pig. Target lesions were centered on the greater curvature of the gastric body. The resected stomachs were incised along the lesser curvature to expose the interior, where no abnormality such as bleeding or perforation was found. The surrounding normal tissues were damaged and changed, but were not detected during endoscopic submucosal dissection. All numbers represent sequentially resected areas.
Fig. 4Tissues from resected specimens pinned on a rubber board after formalin fixation. (Inset) Resected specimens just after the procedure.
Fig. 5Representative histological findings of endoscopic mucosal dissection (ESD) specimens and residual muscularis propria tissue from the Optimos knife group (A-D) and combination knives group (E-H; H&E stain). (A, B) ESD showing minimal injury to the lamina propria and submucosa in the Optimos knife group. (C, D) Residual bed tissue showing minimal injury to the lamina propria and muscularis propria in the Optimos knife group. (E, F) ESD showing minimal injury to the lamina propria and submucosa in the combination knives group. (G, H) Residual bed tissue showing marked injury in the lamina propria and muscularis propria in the combination knives group. Arrows represent the extent of injury. Scale bars represent 50 µm in (B) and (F) and 500 µm in the others.
Fig. 6Comparison of the levels of histological injury between the Optimos knife group and the combination knives group. (A) Extent of injury to the lamina propria in the dissected gastric specimens. (B) Extent of injury to the lamina propria in the remaining gastric bed tissue. (C) Depth of injury to the submucosa in the dissected gastric specimens. (D) Depth of injury to the MP in the remaining gastric bed tissue. LP, lamina propria; ESD, endoscopic mucosal dissection; SM, submucosa; MP, muscularis propria.
Table 1Procedural Data of All 18 Endoscopic Submucosal Dissection Procedures
Table 2Statistical Analysis of Procedural Data
Table 3Extent or Depth of Histological Injury in the Lamina Propria, Submucosa, and Muscularis Propria