Biodegradable Esophageal Stent Placement Does Not Prevent Stricture Formation Following Circumferential Mucosectomy in a Porcine Model.

Eric M Pauli, MD, Steve J Schomisch, PhD, Joseph P Furlan, BS, Amitabh Chak, MD, Jeffrey L Ponsky, MD, Jeffrey M Marks, MD. University Hospitals Case Medical Center, Cleveland, OH


Introduction: Advanced esophageal dysplasia and early cancers have traditionally been treated with esophagectomy. Recently developed tissue ablation techniques are less invasive, but may undertreat and do not permit histological analysis for staging. Endoscopic esophageal mucosectomy (EEM) offers a less-invasive therapy and provides an intact specimen for histo-pathologic assessment. However, high rates and high degrees of stricture formation following EEM limit its applicability. We hypothesized that placement of a self-expanding biodegradable stent (BD-stent; 12 week disintegration time) immediately following circumferential EEM would prevent stricture formation.

Methods: Ten pigs (5 unstented controls, 5 BD-stent) were utilized in the study. Sample size calculations indicated that 5 per group would detect a 25% stricture reduction with a p=0.05 and power of 0.80 using t-test. Following sedation and mechanical ventilation, a flexible endoscope with a band ligator and snare was used to circumferentially incise the mucosal layer approximately 20 cm proximal to the lower esophageal sphincter. A 7-10 cm circumferential segment of tissue was dissected free from the underlying muscle and excised using electrocautery and snare. In the stented group, a 18×120 mm uncovered, self-expanding, woven polydioxanone stent (ELLA-CS, Hradec-Kralove, Czech Republic) was deployed over a 0.035” guidewire. Stents were bridled using a non-absorbable suture passed through the stent interstices and suture to the cheek. Barium sulfate esophagograms were performed weekly to evaluate for percent reduction in diameter, stricture length and proximal dilation. Animals were followed clinically and were euthanized when the stricture exceeded 80% and were unable to gain weight (despite high-calorie liquid diet supplementation) or at 14 weeks.

Results: The control group rapidly developed esophageal strictures; no animal survived beyond the third week of evaluation. At two weeks post-EEM, the BD-stent group had a significant reduction in stricture diameter (77.6% vs 26.6%, p<0.001) and degree of proximal dilation (175% vs 131%, p=0.04) compared to controls. There was no difference in % stricture length between the groups. Survival in the BD-stent group was significantly longer than in the control group (9.2 weeks vs 2.4, p=0.01). However, all BD-stent animals ultimately developed clinically significant strictures (range 4-14 weeks). Comparison between the maximum reduction in diameter and stricture length (immediately prior to euthanasia) demonstrated no differences between the groups. There were no stent related obstructions or migrations.

Conclusions: Circumferential EEM quickly results in a high degree of stricture formation in a porcine model. These strictures result in clinical deterioration (regurgitation, failure to gain weight) within three weeks. The placement of a BD-stent significantly delays the time of clinical deterioration from 2.4 to 9.2 weeks, but does not minimize the maximum degree of luminal narrowing or proximal esophageal dilatation. The timing of stricture formation in the polydioxanone BD-stent group correlated with the known loss of integrity and radial force (6-8 weeks) and the stent disintegration (11-12 weeks). Future areas of investigation will need to focus on the use of fully-covered BD-stents and on the use of BD-stents with a longer in vivo half-life.

Session Number: SS14 – Therapeutic Endoscopy
Program Number: S078

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