Tissue anchors for transmural gut-wall apposition

Background: With the development of NOTES (natural orifice transluminal endoscopic surgery) and efforts to advance gastric reduction surgery, alternatives for robust tissue apposition apart from suturing and current mucosal clipping devices may be valuable. Objectives: We attempted to identify functional tissue anchors that could be deployed endoscopically, with the potential to provide transmural tissue apposition. Design: Short-term animal-survival study. Patients: Domestic pigs, under general anesthesia, underwent open laparotomy, gastrotomy, and manual placement of prototype tissue anchors. Interventions: Four tissue-anchor designs were evaluated (T bar, T bar with mesh bolster, star, basket). Full-thickness gastric plications were manually created in the body and the antrum via laparotomy and were secured with sets of paired anchors, also placed manually via a gastrotomy. In 1 test animal, a pilot gastric reduction was created by forming 2 rows of 4 anchor sets on the anterior and posterior walls to create a tubelike gastric lumen. Main Outcome Measurements: Follow-up endoscopy was performed at 2, 4, and 9 weeks to visually assess the intraluminal appearance of the plications, followed by necropsy and histologic study. Results: There was an overall attrition of the number of anchor sets. At 2 weeks, the T-bar anchors were first to disappear, and the mesh and the star designs began to pull through the gastric folds. At 4 weeks, there was flattening of the plications that involved 6 pairs of mesh anchors. By 9 weeks, 3 pairs of mesh anchors were lost and 3 pairs were associated with flattened folds. At the time of euthanasia, at 4 or 9 weeks, the number of retained anchors associated with intact plications for each group were as follows: T bar, 6 of 9 pairs (67%); mesh, 12 of 18 pairs (67%); basket, 14 of 18 pairs (78%); and star, 2 of 9 pairs (22%). There were no gastric adhesions and no evidence for any inflammatory changes surrounding the stomachs. The tallest plications involved the basket anchors. The basket-anchored plications contained apposed muscularis propria, with serosal fusion evident. The folds from the other anchor types were formed of mucosa and submucosa with or without superficial muscularis propria. Conclusions: The results of this experience are encouraging. The basket tissue anchors appear most promising. These findings suggest that further development of tissue anchors deployed via flexible catheter-based devices may have clinical value for transmural tissue apposition.