Applicability of advanced endoscopic balloon-type irreversible electroporation catheter on the esophagus: Preclinical animal study

Abstract

Background: Irreversible electroporation (IRE) is a new destructive technique that removes undesirable tissues using an electric field. Main mechanism of IRE is through the creation of permanent, nano-sized pores on the cell membranes, resulting in cell death. It poses, however, one technical challenge as contractions of smooth muscle of the gastrointestinal tract may prevent IRE from effectively electroporate the cell. The present study aims to demonstrate the applicability of this newly designed endoscopic balloon-type IRE catheter in destroying undesired tissues.

Methods: The electrical field generated at 1500V with 40 pulses during ablation with the balloon-type catheter in esophagus were simulated using COMSOL Multiphysics. After a pig was anesthetized, a 0.035-inch Jagwire was inserted through the duodenum using a gastroscope. An IRE catheter was then manually advanced into the esophagus along with a guidewire. The fluoroscopy with contrast medium was employed to determine target lesions with clips. Following the sequential ablation along the esophagus, electrical parameters as well as the number of interruptions encountered were recorded. The pigs used in the experiments were sacrificed after 24 hours and tissue specimens obtained were evaluated using H&E and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.

Results: Based on the COMSOL simulation, the heated portion, approximately 57 degrees of Celsius, was observed only at the edge of the electrodes. Fluoroscopy demonstrated the balloon-type catheter was not adjacent to the heart and tightly blocked the lumen of esophagus as it adheres to the mucosal layer during inflation. The IRE catheter was able to overcome muscle contractions during ablative process and deliver all electrical energy of the scheduled sequences. A total of 12 ablations were performed in three pigs, and the success rate of balloon catheter was 91.7% (11/12). Histological slides from H&E staining and TUNEL assay showed nuclei, stained brown, which indicates apoptosis at the ablation site.

Conclusions: The IRE balloon-type catheter demonstrated its applicability and effectiveness as an electroporation-based treatment in esophagus as validated in the experimental results. Further studies regarding electrodes improvement to heat-free condition and its safety related assessment would be needed.