Endoscopic suture fixation of gastroesophageal stents with and without submucosal injection in a porcine model

Victor T Wilcox, MD, Brian J Dunkin, MD, FACS, Nabil Tariq, MD, FACS, Albert Y Huang, MD, Patrick R Reardon, MD, FACS. Methodist Institute for Technology, Innovation & Education (MITIE).

BACKGROUND: Self expanding metal stents (SEMS) are useful for treating leaks after bariatric or upper gastrointestinal (GI) surgery. Stent migration is common, however, occurring in 12 to 40% of patients and can lead to additional costs, repeat procedures, and potential morbidity. Methods utilized to reduce migration include clip fixation and “sleeving” a second stent within the first to increase the proximal “landing zone”. Recently, suturing the stent into place endoscopically has been shown to increase pullout forces in a porcine model, but raises concern about full thickness suture penetration into adjacent organs.

STUDY AIMS: We hypothesized that submucosal injection prior to suture fixation would decrease the likelihood of full thickness suture penetration while still providing significantly greater pull-out forces than no sutures or endoscopic clipping.

METHODS: 155mm SEMS were placed into the esophagus of porcine explant models with 75mm of the stent within the esophagus and 80mm extending beyond the gastroesophageal junction distally so as to mimic stent placement for leaks after upper GI and bariatric surgery. A force meter was used to measure the pullout force required to dislodge the stent in Newtons (N). In each explant, the stent was first deployed without fixation and the pullout force measured to act as a control. The stent was then replaced and the explant randomized to one of three groups (n=5 per group): fixation with two clips, two endoscopic sutures without submucosal elevation, or two endoscopic sutures with submucosal elevation. The pullout forces were again measured and the ratio of the experimental pullout force to the control calculated as a measure of the efficacy of the fixation. After each trial, the specimens were examined for signs of transmural penetration. Suture fixation was accomplished using the OverStitchTM Endoscopic Suturing Device (Apollo Endosurgery, Austin, TX). Paired-samples t-test and Fischer’s exact two tailed test were used to compare study groups to controls and one-way ANOVA for comparison among groups.

RESULTS: The control pullout force was 3.27 ± 0.67N (n=15). Endoscopic suture fixation without submucosal injection resulted in a statistically significant increase in stent pullout force (23.01 ± 5.05N; mean force ratio 765%; 95% confidence interval [CI]: 362-1167%; p < 0.01). Endoscopic suture fixation with submucosal injection also resulted in a statistically significant increase in pullout force (14.26 ± 4.51N; mean force ratio 462%; 95% confidence interval [CI]: 281-643%; p < 0.01) while fixation with clips did not increase the pull out force (3.40 ± 0.59N; mean force ratio 108%; 95% confidence interval [CI]: 56%-159%; p = 0.988). Suture fixation without submucosal elevation was also statistically stronger than with elevation, but 7 of 10 sutures placed without submucosal elevation penetrated full thickness versus 0 of 10 with submucosal elevation (p = 0.003).

CONCLUSION: Endoscopic suture fixation of SEMS with or without submucosal elevation results in a statistically significant increase in pullout force compared to clip or no fixation. However, suture fixation with submucosal injection avoids transmural suture penetration and may prevent injury to nearby organs and structures.

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