Anatomy-shaped design of a fully-covered, biliary, self-expandable metal stent for treatment of benign distal biliary strictures

BACKGROUND AND STUDY AIMS The treatment success of benign biliary strictures with fully covered metal stents (CSEMS) is altered by high stent dislocation rates. We aimed to evaluate a new stent design to prevent dislocation. PATIENTS AND METHODS Patients with benign biliary strictures were treated with a newly designed double-coned stent (dcSEMS). Mechanical analysis of the new stent was performed and it was compared with a cylindrical stent. RESULTS A total of 13 dcCSEMS were implanted in 11 patients (2 female, 9 male, median age 47, range 33 - 71). All patients had distal biliary strictures due to chronic pancreatitis. No stent migration occurred. In all but one patient the stents were removed. One patient refused stent extraction and was lost to follow up. Stent occlusion occurred twice leading to cholangitis in both cases. The duration of stent treatment was 170 days (range 61 - 254). After extraction only one patient had early recurrent stricture and received the same stent again. Three stents showed minimal tissue granulation at the papilla. One stent presented ingrowth at the proximal end and was removed after implantation of a second fully covered stent. Mechanical examination revealed significantly lower radial expansion force of the new stent as compared to the cylindrical stent. CONCLUSIONS The new stent design has a low rate of migration. Biomechanical properties may explain this effect.