Selective tissue elevation by pressure injection (STEP) facilitates endoscopic mucosal resection (EMR).

Endoscopic mucosal resection and endoscopic submucosal dissection have become more common in treatment of flat superficial tumors of the gastrointestinal tract. Submucosal injection is used to try to avoid complications and improve the technical feasibility of the procedure. However, the method has its limitations, particularly when treating extensive flat tumors in the colon. The water-jet dissector has already demonstrated its capacity for selective cutting with the dissection of parenchymatous. This chapter addresses a new indication, transmucosal mucosal elevation, together with first clinical results. After carrying out animal experiments into the physical properties using animal preparations and freshly resected human specimens from operations, our work group investigated and compared the applicability of the procedure using different carrier fluids. Six test substances-hydroxyethyl starch (HES), Gelafusal, Infukoll, Glucose 50 und isotonic saline solution-were injected into six anesthetized pigs; the height of the submucosal fluid cushion created by the injection was measured endosonographically over a period of 45 minutes. Endoscopic mucosal resection was subsequently carried out, and the resected specimen together with the area it was taken from were assessed histologically. Using commercially available NaCl cartridges, applied by the way of endocapillaries, 18 lesions were elevated in a series of 12 patients and subsequently resected endoscopically. All investigated substances could be applied without difficulty using the Helix HydroJet (Erbe Elektromedizin GmbH, Waldhörnle-Str., Tübingen, Germany). The plasma expanders (HES and Gelafundin 4%, B. Braun Melsungen AG, Melsungen, Germany) produced longer lasting fluid cushions than the isotonic solutions. Mucosal resections could be carried out in all cases with all of the solutions. Histological investigation confirmed the selective nature of the fluid accumulation in the submucosal tissue, which spared the lamina mucosae and lamina muscularis propria. The first clinical applications were successful. The technique of selective fluid accumulation in the submucosa by pressure injection, selective tissue elevation by pressure injection (STEP), presented herein for the first time in a clinical setting, makes it easier to carry out endoscopic mucosal resections and expands the use of this technique to treatment of extended lesions. The manufacturer has announced his intention of combining this technology with an IT-knife, so further improvements can be expected.