3462 Depth of injury following endoscopic spray cryotherapy: eus assisted evaluation of mucosal ablation and subsequent healing in the swine model.

Abstract

BACKGROUND: In our previous studies we reported a novel technique using spray cryotherapy through an endoscope to achieve mucosal ablation in the swine esophagus.We described its feasibility, efficacy and safety and then documented both the acute, subacute and longterm endoscopic/histologic appearance of the esophagus by performing serial EGD and biopsy over a 3-month period. Unresolved was the extent and evolution of the cryo injury. AIM: To prospectively assess the extent of mucosal ablation and depth of injury using EUS post cryotherapy in the swine esophagus. METHODS: Two Yorkshire swine underwent baseline EUS of the esophagus followed by a 45 second cryoburn to the mucosa of the distal esophagus. EUS of the treated areas was then performed using a 20MHz Olympus ultrasound probe at 5 min,48 hours, one and two weeks. A third swine underwent cryotherapy to the distal esophagus and again in the mid-esophagus at 48 hrs followed by EUS and esophagectomy for full thickness biopsy of each cryo site. RESULTS: Full thickness biopsy immediately post cryo revealed RBC extravasation into the submucosa with normal overlying epithelium, while the site 48 hrs. post cryo revealed complete ablation of the mucosal layer which measured 0.3-0.5 mm. EUS (see table) revealed edema/expansion of the mucosa and submucosa immediately post injury with expansion of all layers at one week and resolution by two weeks. CONCLUSIONS: Based on these preliminary data, biopsy confirms complete mucosal ablation with transmural inflammation the greatest degree of which is in the adventitia and to a lesser extent superficially. EUS demonstrates transient edema but no significant injury to underlying structures. Endoscopic cryotherapy apears to be an ideal modality for mucosal ablation for which Barrett's epithelium and perhaps vascular ectasias should be considered.