Radial force and wire structure determine the onset of covered self-expandable metal stent migration in endoscopic ultrasound-guided hepaticogastrostomy: Measurement of sliding-resistance force using a porcine model.

BACKGROUND:Self-expandable metal stent (SEMS) migration after endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) is a severe complication. The migration risk could be related to the surface friction of SEMS, assumed to be affected by the wire structure and mechanical properties, including radial force (RF); however, their relevance remains unclear. This experimental study aimed to assess the mechanical properties of SEMS involved in the onset of stent migration by measuring the sliding-resistance force (SF) as the SEMS moves through the stomach wall. METHODS:The SF of seven types of 8-mm diameter SEMS (four braided and three laser-cut types) and porcine stomach wall was measured with a universal testing machine. The SF of each SEMS was measured three times, and the average maximum SF (SFmax) was used for analysis. The correlation between SFmax and RF of each SEMS was evaluated. RESULTS:SFmax and RF showed a very strong positive correlation (r = 0.92). Compared to the regression line predictions in the scatter plots of SFmax and RF, the SFmax of laser-cut and braided type SEMSs had positive and negative residuals, respectively. CONCLUSIONS:Selecting a laser-cut type SEMS with a higher RF may more effectively prevent the onset of stent migration against the stomach wall in EUS-HGS.