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Introduction: Ablation of Barrett’s with high-grade dysplasia has become standard. The most common ablation technique uses radiofrequency energy, but a drawback is the requirement that the devices be used either separate from or attached to the outside of an endoscope. An alternative is cryoablation, but current cryotherapy devices are cumbersome, require gastric venting, and ablation depth is difficult to standardize. A device that goes down the working channel of an endoscope that delivers a uniform and reproducible ablation would potentially be safer and more user-friendly. The aim of this study was to assess depth of injury related to time of ablation using a novel through-the-scope balloon-based cryotherapy device.

Methods: Patients with esophageal cancer were enrolled in a multi-center prospective trial evaluating a novel cryoballoon ablation device prior to esophagectomy. The device is a through-the-scope, highly compliant balloon catheter that is inflated and cooled by an inert refrigerant delivered from a handheld unit. The balloon automatically sizes to the esophageal lumen. One to two ablations were performed in separate areas in each patient in mucosa proximal to the tumor. After resection, the ablation sites were removed as a full-thickness block and examined histologically by a central study pathologist. Symptoms were assessed prior to ablation, on the day of and 3 days after the procedure using a standardized questionnaire with a 10-point scale.

Results: Twenty-one ablations were performed in 13 patients for 6, 10, 12 or 14 seconds, and the esophagus was removed 0, 4 or 7 days after the procedure. The ablation was in squamous mucosa in 12 patients and in dysplastic Barrett’s in 1 patient. There were no adverse events and no perforations. No pain was present in 78% of patients the day of the procedure and in 89% of patients 3 days after the procedure. The mean scores for pain on the day of and at 3 days after the procedure were 0.89 and 0.2 respectively. Swallowing difficulty was present in 11% on the day of and in 22% at 3 days after the procedure. The mean scores for swallowing difficulty on the day of and at 3 days after the procedure were 0.3 and 0.6 respectively. Details of the histology are shown (Table).

Conclusions: Ablation with a novel cryoballoon device for 10-14 seconds results in substantial mucosal injury with minimal pain or impaired swallowing. Depth of necrosis was maximal at day 4 and was typically into the superficial muscularis propria. By 7 days the injury was resolving, a finding similar to previous work with this device in animals. Major advantages of this device include the ability to standardize the ablation along with the ease of use and quickness of the procedure. Future studies will assess the risk of stricture and efficacy for Barrett’s ablation with this device.

Day (post-esophagectomy)	0	0	0	0	4	4	4	7	7	7
Ablation time (sec)	6	10	12	14	10	12	14	10	12	14
n	1	1	1	4	4	2	5	1	1	1
Circumferential mucoscal ablation; Avg and (range) when n>1	30%	80%	50%	3.75% (0-10)	64% (25-90)	80% (65-95)	68% (50-80)	15%	0	100%
Depth of necrosis* Avg, (range)	1	1	1	1 (0-1)	3 (3-3)	3 (2-4)	3 (2-4)	1	1	2
Adjacent injury* Avg, (range)	0	0	0	1 (0-1)	2 (0-3)	3 (2-4)	2 (0-3)	0	0	2

*Key: 0=no necrosis; 1=necrosis only involving mucosa including or superficial to muscularis mucosa; 2=necrosis into but not through submucosa; 3=necrosis into superficial muscularis propria; 4=necrosis involving full-thickness of muscularis propria, no perforation