PURPOSE: This study was designed to compare the migration rates of covered stents with eight, four, and zero barbs in urethra-mimicking bovine pericardium models. METHODS: Three types of polytetrafluoroethylene-covered retrievable self-expandable prostatic stents, with eight, four, and zero barbs, were tested in bovine pericardium models, consisting of normal saline-filled acrylic containers with tubes at both ends and a replica of the human urethra. The barbs were 2 mm in length and projected 60° toward the urinary bladder. The anti-migration force (AMF) and resistance force against stent removal (RFSR) were measured by an automatic push-pull gauge system at a fixed rate (2 mm/s). RESULTS: Significant differences in AMF among the three stent types were detected (P < 0.001). Median AMF was far greater for eight-barbed than for four-barbed stents (11.96 vs. 7.55 N, P = 0.003). For stent removal, the difference between 4- and 8-barbed stents were not significant in median static (5.54 vs. 6.08 N, P = 0.15) or sliding (prostatic urethra, 5.32 vs. 5.59 N, P = 0.65; membranous urethra, 7.78 vs. 8.57 N, P = 0.364) RFSR. No perforations or scratched traces were observed during removal of these stents. CONCLUSIONS: The inclusion of eight barbs projecting 60° toward the urinary bladder were not only effective against stent migration in this model but suggests that these stents may be suitable for the treatment of prostatic urethral strictures without severely irritating the tissue. However, whether these results translate into living urethral tissue is unclear, necessitating further studies.
PURPOSE: This study was designed to compare the migration rates of covered stents with eight, four, and zero barbs in urethra-mimicking bovine pericardium models. METHODS: Three types of polytetrafluoroethylene-covered retrievable self-expandable prostatic stents, with eight, four, and zero barbs, were tested in bovine pericardium models, consisting of normal saline-filled acrylic containers with tubes at both ends and a replica of the human urethra. The barbs were 2 mm in length and projected 60° toward the urinary bladder. The anti-migration force (AMF) and resistance force against stent removal (RFSR) were measured by an automatic push-pull gauge system at a fixed rate (2 mm/s). RESULTS: Significant differences in AMF among the three stent types were detected (P < 0.001). Median AMF was far greater for eight-barbed than for four-barbed stents (11.96 vs. 7.55 N, P = 0.003). For stent removal, the difference between 4- and 8-barbed stents were not significant in median static (5.54 vs. 6.08 N, P = 0.15) or sliding (prostatic urethra, 5.32 vs. 5.59 N, P = 0.65; membranous urethra, 7.78 vs. 8.57 N, P = 0.364) RFSR. No perforations or scratched traces were observed during removal of these stents. CONCLUSIONS: The inclusion of eight barbs projecting 60° toward the urinary bladder were not only effective against stent migration in this model but suggests that these stents may be suitable for the treatment of prostatic urethral strictures without severely irritating the tissue. However, whether these results translate into living urethral tissue is unclear, necessitating further studies.
Authors: Kapil Sethi; Michael Bozin; Tebogo Jabane; Richard McMullin; David Cook; Rob Forsyth; Lachlan Dodds; Lydia Johns Putra Journal: Investig Clin Urol Date: 2017-10-23