title: Combination of water-jet dissection and needle-knife as a hybrid knife simplifies endoscopic submucosal dissection.
abstract: BACKGROUND
  The safety and efficacy of endoscopic submucosal dissection (ESD) is very dependent on an effective injection beneath the submucosal lamina and on a controlled cutting technique. After our study group demonstrated the efficacy of the HydroJet in needleless submucosal injections under various physical conditions to create a submucosal fluid cushion (Selective tissue elevation by pressure = STEP technique), the next step was to develop a new instrument to combine the capabilities of an IT-Knife with a high-pressure water-jet in a single instrument. In this experimental study, we compared this new instrument with a standard ESD technique.
  
  
  METHODS
  Twelve gastric ESD were performed in six pigs under endotracheal anesthesia. Square areas measuring 4-cm x 4-cm were marked out on the anterior and posterior wall in the corpus-antrum transition region. The HybridKnife was used as an standard needle knife with insulated tip (i.e., the submucosal injection was performed with an injection needle and only the radiofrequency (RF) part of the HybridKnife was used for cutting (conventional technique)) or the HybridKnife was used in all the individual stages of the ESD, making use of the HybridKnife's combined functions (HybridKnife technique). The size of the resected specimens, the operating time, the frequency with which instruments were changed, the number of bleeding episodes, and the number of injuries to the gastric wall together with the subjective overall assessment of the intervention by the operating physician were recorded.
  
  
  RESULTS
  The resected specimens were the same size, with average sizes of 16.96 cm(2) and 15.85 cm(2) resp (p = 0.8125). Bleeding episodes have been less frequent in the HybridKnife group (2.83 vs. 3.5; p = 0.5625). The standard knife caused more injuries to the lamina muscularis propria (0.17 vs. 1.33; p = 0.0313). The operating times had a tendency to be shorter with the HybridKnife technique (47.18 vs. 58.32 minute; p = 0.0313).
  
  
  CONCLUSIONS
  The combination of a needle-knife with high-pressure water-jet dissection improved the results of endoscopic submucosal dissection in this experimental setting. Because the frequency of complications is still high, further improvements to the instrument are necessary.
authors.affiliation: Department of Surgery, University Hospital Mannheim, Ruprechts-Karls-Universität, Heidelberg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Lingenfelder
authors.forename: Klaus
authors.initials: K
authors.lastname: Fischer
authors.forename: Moritz G
authors.initials: MG
authors.lastname: Sold
authors.forename: Stefan
authors.initials: S
authors.lastname: Post
authors.forename: Markus D
authors.initials: MD
authors.lastname: Enderle
authors.forename: Georg F B A
authors.initials: GF
authors.lastname: Kaehler