2005 Abstracts: Endoscopic Placement, Long-Term Retention and Removal of Hydrogel Prostheses at the Lower Esophageal Sphincter in Mini-Swine: 3.8 Years Follow-up
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Endoscopic Placement, Long-Term Retention and Removal of Hydrogel Prostheses at the Lower Esophageal Sphincter in Mini-Swine: 3.8 Years Follow-up
David W. Easter, UCSD, San Diego, CA; Glen Lehman, Indiana University Hospital, Indianapolis, IN; Fred J. Clubb, Texas Heart Institute, Houston, TX; Yelena Tropsha, Medtronic Gastroenterology, Shoreview, MN
INTRODUCTION: Previous short-term animal studies have demonstrated the safety, durability and reversibility of hydrogel prostheses placed at the lower esophageal sphincter (LES) using a novel delivery device.
PURPOSE: We report the long-term rates of hydrogel retention, stability, and the success with endoscopic removal methods at the conclusion of our animal study. METHODS: Seventeen mini-swine were implanted with multiple hydrogel prostheses placed at the LES using a novel endoscopic delivery device (Gatekeeper-TM, Medtronic, Inc.) Early methods utilized a beveled needle insertion technique (n = 11 animals) and late methods used a conical trocar needle system (n = 6 animals.)Animals were periodically monitored with fluoroscopy and/or endoscopy to assess stability and retention rates. Hydrogel size after insertion/hydration was 15mm length by 5.5mm diameter. Animals were sacrificed at intervals up to 3.8 years (n = 4 at >3.4 yrs). Prostheses were explanted endoscopically 3-weeks prior to sacrifice, or at sacrifice, using a technique of needle-knife cautery and suction into a ligating cap. RESULTS: The first two weeks of followup was the most common time interval to lose prostheses after the successful placement of hydrogels. The long-term retention of prostheses placed with the beveled needle technique was 50%. The trocar method's retention rates ranged from 71-100%, depending upon the time of animal sacrifice. Standard endoscopy methods allowed for successful hydrogel explantation in multiple animals (n = 4). No macroscopic evidence of hydrogel degradation was evident upon removal or sacrifice. Followup endoscopy at removal sites in live animals revealed no visible signs of complication. Histopathology on intact and explanted sites demonstrated normal healing without excessive inflammation. CONCLUSION: The Gatekeeper-TM system of endoscopic placement of hydrogel prostheses at the LES in mini-swine results in stable long-term implants. The current method of conical trocar design yields acceptable delivery and retention rates. Prostheses can be safely removed using standard endoscopic methods without apparent clinical sequelae. Human studies are underway.
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