Study of the Behavior of a Bell-Shaped Colonic Self-Expandable NiTi Stent under Peristaltic Movements

Abstract

Managing bowel obstruction produced by colon cancer requires an emergency intervention to patients usually in poor conditions, and it requires creating an intestinal stoma in most cases. Regardless of that the tumor may be resectable, a two-stage surgery is mandatory. To avoid these disadvantages, endoscopic placement of self-expanding stents has been introduced more than 10 years ago, as an alternative to relieve colonic obstruction. It can be used as a bridge to elective single-stage surgery avoiding a stoma or as a definitive palliative solution in patients with irresectable tumor or poor estimated survival. Stents must be capable of exerting an adequate radial pressure on the stenosed wall, keeping in mind that stent must not move or be crushed, guaranteeing an adequate lumen when affected by peristaltic waves. A finite element simulation of bell-shaped nitinol stent functionality has been done. Catheter introduction, releasing at position, and the effect of peristaltic wave were simulated. To check the reliability of the simulation, a clinical experimentation with porcine specimens was carried out. The stent presented a good deployment and flexibility. Stent behavior was excellent, expanding from the very narrow lumen corresponding to the maximum peristaltic pressure to the complete recovery of operative lumen when the pressure disappears.

Colorectal stenting as first-line treatment in acute colonic obstruction

“…Comparison between colonic SEMS manufactured by major stent companies show no important differences between them [40] . In addition, manufacturers are continuously working on stent improvement to allow a proper obstruction decompression [46] . It is better to use bare (uncovered) stents for MCRO rather than covered ones that are more prone to have complications [41] .…”

Computational analysis of mechanical stress in colonic diverticulosis

“…Computational models have been established previously for the normal colon tissue. Most are, however, based on isotropic material models [16][17][18] despite the anisotropic nature of the colon tissue. One study implemented an anisotropic computational model based on uniaxial testing 19 .…”

Feasibility of using bulk metallic glass for self-expandable stent applications

“…Some of the most popular stent materials include nitinol, stainless steel, cobalt-chromium alloy, and other polymeric alloys. [1][2][3][4][5][6][7][8][9][10][11][12] Stents can be broadly classified into self-expandable stent and balloon-expandable stent. 13 Particularly, self-expandable stents are used extensively to treat occlusions in endovascular lumen both in central and peripherals vessels, and also as bio-prosthetic heart valves frames.…”