An internally covered (lined) self-expanding metal esophageal stent: tissue response in a porcine model.
BACKGROUND
Self-expandable metal stents (SEMS) palliate malignant dysphagia but may embed in tissue, produce granulation tissue, and prevent removal.


OBJECTIVE
Our purpose was to evaluate in a porcine model the tissue response induced by a new esophageal SEMS completely coated internally rather than externally.


METHODS
Eight Yucatan pigs were studied. Each animal underwent placement of 2 stents: 1 study stent and 1 control stent. SEMS were placed proximally or distally by random assignment. Follow-up endoscopy was performed 1, 2, 3, and 4 weeks after implantation. Ease of stent removal was assessed at 2 weeks and 4 weeks after placement.


METHODS
Animal laboratory.


METHODS
Endoscopic placement of study stents (Alveolus ES-STS, Alveolus, Inc, Charlotte, NC; 18 mm diameter, fully covered internally) and control stents (Ultraflex stent, Boston Scientific, Natick, Mass; microvasive, 18 mm midbody, subtotally covered externally).


METHODS
Extent of granulation tissue and stent-induced esophageal injury.


RESULTS
The tissue hyperplasia response of the study stents was endoscopically graded as mild to moderate. All study stents were endoscopically removed easily and atraumatically. Control stents produced severe granulation tissue formation with complete embedding of the uncovered stent ends; endoscopic removal was possible but resulted in trauma and endoscopically visible bleeding. Histopathologic findings revealed minimal tissue response at the ends of the study stents and severe pseudopolyps in the embedded portion of the control stent. Stent migration occurred in 7 of 8 study stents and 4 of 8 control stents.


CONCLUSIONS
Animal model lacks stricture.


CONCLUSIONS
Fully internally lined SEMS may resist tissue embedding and hyperplasia and may be removable. Human studies are needed to assess applicability to treatment of benign and malignant esophageal disease.
Baron
Todd H
TH
Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Burgart
Lawrence J
LJ
Pochron
Nicole L
NL
D000818:Animals; D016099:Endoscopy, Gastrointestinal; D004947:Esophagus / Q000473:pathology; D005260:Female; D006097:Granulation Tissue / Q000473:pathology*; D011474:Prosthesis Design; D015607:Stents / Q000009:adverse effects; D013552:Swine; D016610:Tissue Embedding