Post written by Ryohei Hirose, MD, PhD, from the Department of Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, and the Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
The development and clinical introduction of high-performance submucosal injection materials (SIMs) will greatly contribute to the realization of safe and rapid endoscopic treatment for early gastrointestinal cancer and polyps. The ideal high-performance SIM should satisfy all 3 conditions: (i) create and maintain high submucosal elevation; (ii) be able to be injected with an endoscopic injection needle consisting of a long catheter and a fine needle; and (iii) allow endoscopists to control the creation site of the submucosal cushion. To satisfy all 3 conditions above, we devised a 2-solution type next-generation SIM consisting of an aqueous solution containing cations (ie, calcium chloride aqueous solution) and a polysaccharide solution that can be gelled by cations (ie, sodium alginate aqueous solution).
Viscous solutions such as sodium hyaluronate and hydroxypropyl methylcellulose have been widely used as current high-performance SIMs. Although these viscous solutions provide increased SIM performance as their concentration (viscosity) increases, their injection pressure also increases, making injection difficult. Thus, SIMs that exceed the performance of the current SIMs have not yet been introduced clinically because it is difficult to satisfy all the above 3 conditions.
Since these 2 solutions are relatively low in viscosity, they can be easily injected separately with an endoscopic injection needle and can change into a highly viscous submucosal cushion when mixed and gelled in the submucosa. In addition, since the viscosity of the submucosal cushion is still low when only the first solution is injected, even if the submucosal cushion is created at a site different from the intended site, it disappears in a short time and does not continue to interfere with the treatment procedure. The next-generation SIM facilitates repeat injection when the submucosal cushion is created at an inappropriate site. Thus, the next-generation SIM devised and developed in this study is an ideal SIM that achieves both extremely high performance and high flexibility.
Figure 1. Definition of this study. A, Submucosal injection procedure with low-performance submucosal injection materials (SIMs) and the disadvantages of using low-performance SIM. B, Submucosal injection procedure with high-performance SIMs and disadvantages of using high-performance SIM. C, Overview of the 2-solution-type next-generation SIM and the submucosal injection procedure with the next-generation SIM (2-step injection system). D, Alternative usage of the next-generation SIM.
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