Effect of robot-assisted gastric ESD in difficult ESD locations.

355 Background: Since its introduction, endoscopic submucosal dissection (ESD) has become a standard treatment for early malignant lesions of stomach. However, ESD is technically demanding and it bears a high risk of complication for beginners. The difficulty of the ESD technique tends to depend on the location of the lesion. We compared and analyzed the efficacy of the ESD assistive robot that we developed in the location where stomach ESD is considered difficult. Methods: We have developed an automated simulator that can implement gastric ESD locations. An EndoGel (Sunarrow, Tokyo, Japan) was attached to the simulator to implement a virtual gastric location where ESD is difficult. "Difficult ESD locations" were selected in consideration of the location where a lot of muscle damage and frequent blind dissections occurred when conventional ESD was performed. An experienced endoscopist performed ten robot-assisted ESDs or conventional ESDs in 3 difficult and 3 easy positions, respectively. Results: While there was no significant difference in dissection speed of robot ESD and conventional ESD in easy positions, the submucosal dissection speed was remarkably faster in robotic ESD than in conventional ESD in difficult positions (P < 0.05). In difficult positions, there was significantly more muscle damage in conventional ESD than in robotic ESD. (P < 0.05). Conclusions: Dissection speed was greatly improved when assistive robots aided gastric ESD procedures in difficult locations. Our robotic device can thus provide simple, effective, and safe multidirectional traction during gastric ESD in difficult location.