Representative endoscopic and CT images of the stented ET over time.

(A) Endoscopic images taken immediately after stent placement, showing the proximal end of the Mg stent (arrows) in the porcine ET. The proximal end of the stent with mild secretion (arrows) is observed around the Mg stent at two weeks, while the Mg stent is not observed at four weeks (arrowheads). (B) 3D-reconstructed CT images of the degraded Mg stent showing a residual Mg stent with a collapsed distal end at two weeks and only a small piece of the Mg stent at four weeks. Note. CT, computed tomography; Mg, magnesium; ET, Eustachian tube.</p

Schematic image of an absorbable magnesium stent to manage ETD showing prevention of stent-induced tissue hyperplasia and maintaining the ET patency.

Schematic image of an absorbable magnesium stent to manage ETD showing prevention of stent-induced tissue hyperplasia and maintaining the ET patency.</p

Representative histological images of the porcine ET and histological findings.

(A) Histological images showing the submucosal tissue hyperplasia increased at two weeks and then significantly decreased at four weeks. (B) Histological results of the thickness of submucosal tissue hyperplasia and the degree of inflammatory cell infiltration in the proximal and distal portions of the stented ET over time after the Mg stent placement. Note. Mg, magnesium; ET, Eustachian tube.</p

The Mg stent and the technical steps of ET stent placement under endoscopic guidance.

Photographs showing (A) the Mg stent loaded onto a balloon catheter and (B) when fully expanded. (C) Endoscopic image showing the nasopharyngeal ostium (arrowheads). (D) The steerable guiding sheath (arrows) was inserted into the nasopharyngeal ostium. (E) The balloon catheter crimped with the Mg stent (arrowheads) is advanced into the ET. (F) The balloon catheter was fully inflated with saline. (G) After verifying the fully expanded stent (arrows), the sheath with the balloon catheter was removed. (H) An endoscopic image of the Mg stent (arrowheads) in the porcine ET. Note. Mg, magnesium; ET, Eustachian tube.</p

Surface morphologies of the Mg stent and mass loss rates.

(A) SEM images showing the size and number of the cracks increasing over time (arrows) on the surface of Mg stent samples obtained at one, two, and four weeks, respectively. (B) The bridges (arrows) between the struts are disconnected, and the strut was sequentially separated. (C) A graph depicting the mass loss rates of the Mg stent over a four-week period. Note. Mg, magnesium; SEM, scanning electron microscopy.</p

Self-Expandable Electrode Based on Chemically Polished Nickel–Titanium Alloy Wire for Treating Endoluminal Tumors Using Bipolar Irreversible Electroporation

The application of irreversible electroporation (IRE) to endoluminal organs is being investigated; however, the current preclinical evidence and optimized electrodes are insufficient for clinical translation. Here, a novel self-expandable electrode (SE) made of chemically polished nickel–titanium (Ni–Ti) alloy wire for endoluminal IRE is developed in this study. Chemically polished heat-treated Ni–Ti alloy wires demonstrate increased electrical conductivity, reduced carbon and oxygen levels, and good mechanical and self-expanding properties. Bipolar IRE using chemically polished Ni–Ti wires successfully induces cancer cell death. IRE-treated potato tissue shows irreversibly and reversibly electroporated areas containing dead cells in an electrical strength-dependent manner. In vivo study using an optimized electric field strength demonstrates that endobiliary IRE using the SE evenly induces well-distributed mucosal injuries in the common bile duct (CBD) with the overexpression of the TUNEL, HSP70, and inflammatory cells without ductal perforation or stricture formation. This study demonstrates the basic concept of the endobiliary IRE procedure, which is technically feasible and safe in a porcine CBD as a novel therapeutic strategy for malignant biliary obstruction. The SE is a promising electrical energy delivery platform for effectively treating endoluminal organs