Balloon-based esophageal cryoablation with a novel focal ablation device: Dose-finding and safety in porcine and human models

The new Cryoballoon Focal Ablation System (CbFAS), a through-the-scope catheter with batterypowered handle that delivers cryogenic fluid into an inflated balloon, differs from current cryotherapy methods used for treatment of Barrett's epithelium. In this dose-finding study, short- and long-term histopathological effects and safety of the CbFAS were evaluated. Cryoablations with (supra)therapeutic durations (4-24 seconds) were performed in pigs that survived for 12 or 48 hours or 4 or 28 days. Next, cryoablations (durations based on animal data) were performed in normal mucosa of esophageal cancer patients scheduled to undergo esophagectomy. The outcome parameters, the occurrence of any bleeding or perforation, the histological presence of edema, inflammation, and necrosis throughout the esophageal wall layers, were evaluated. A total of 60 cryoablations were performed in 11 pigs. 48 hour cryoablations with therapeutic durations (4-10 seconds) resulted in edema/inflammation as deep as the serosa and necrosis ranging from submucosa to serosa with a median depth of 3.2 mm. In 4 day cryoablations this was in the serosa, and muscularis tunica to serosa at a median depth of 4.5 mm, respectively. No necrosis or inflammation remained after 28 days, not even after supratherapeutic cryoablation (12-24 seconds). No acute or delayed bleeding or perforation was observed. Next, eight 6-second cryoablations were performed in four patients. Direct postablation mucosal necrosis was observed; after 4 days necrosis and inflammation was limited to the submucosa. CbFAS cryoablation penetrates deeply into the esophageal wall layers resulting in severe early ablation. After 4 weeks, little injury and no fibrosis remain, even after supratherapeutic durations of administration, suggesting that CbFAS combines deep ablation with a potentially favorable safety profile.