The Diamond™ endobiliary stent (Microvasive, Natick, MA) is a self-expanding, metallic stent, constructed of nitinol wire strands laser-welded in a configuration conferring high radial-force and kink-resistant properties. The stent is compressed onto a flexible delivery catheter by a transparent plastic oversheath with a 3 mm outer diameter. Post-deployment diameter is 10 mm, lengths: 4, 6, & 8 cm. Initial evaluation has been previously reported. We report our accumulated preclinical evaluation here. Methods: Duodenoscopy was performed on 13 pigs (35kg) using general anesthesia. Stents were placed under standard endoscopic and fluoroscopic guidance. To assess deployment, multiple stents were placed in most subjects and immediately removed with biopsy forceps. Patency and bio-tolerance were assessed by long-term follow-up in 9. The following parameters were assessed: ease of delivery & deployment (4 pt scale); expansion (measured by retrieval balloon): fluoroscopic appearance; accuracy of deployment (within 5 mm of intended margins); repositioning; bio-tolerance; histopathology; and complications. Results: A total of 34 stents (# per length = 6, 3, 25) were placed over 6 sessions. The delivery system passed easily through the Olympus TJF-100 duodenoscope, over a .035″ guidewire, and through the un-adultered sphincter choledocus in all cases. Stents deployed with a 1:1 responsiveness (ease of delivery = 3.5; ease of deployment = 3.8). Stents deployed to their full diameter immediately on release. The stent lattice-work and proximal and distal radiographic markings were visible fluoroscopically. Accuracy of deployment was 96%. A partially deployed stent (50%) could be repositioned more distally in the CBD but could not be advanced more proximal nor recaptured. Deployed stents that traversed the ampulla could be immediately removed with a snare or biopsy forceps. At mean 8.6 wk (range 7-10 wk) follow-up no survival subjects had clinical evidence of biliary obstruction or stent related complications. Necropsy in 8 subjects demonstrated minimal to no appreciable epithelial hyperplasia or biliary sludge accumulation grossly or microscopically. Stent migration was observed in one subject. One trans-papillary stent was attempted and successfully removed with a forceps at 7 weeks. No procedure related complications were encountered. Conclusions: 1) The Diamond endobiliary stent demonstrated ease of delivery without sphincterotomy; full and accurate deployment; and excellent bio-tolerance. 2) This endobiliary stent has potential advantages over currently available biliary stents warranting clinical investigation.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging