Enteral stent construction: Current principles

Abstract

A B S T R A C TThe insertion of self-expanding stents into malignant strictures of the small and large bowel has become a routine procedure around the world. However, stent development has happened very much on a "trial & error" approach, based mostly on bright ideas of enthusiastic individuals or marketing decisions by the manufacturer. A large variety of stents are commercially available, covered to a variable degree by a membrane to reduce tissue ingrowth. However, in vitro characteristics and in vivo behavior vary significantly between stents and few operators are aware of the differences. While the ideal stent still remains to be defined, it is important that interventionists understand the variations, in order to make the best possible choice for the individual patient. This article illustrates current principles of stent construction.

Esophageal Stenting: How I Do It

“…The stent is available in lengths varying from 8 to 15 cm and a body diameter of 20 mm with flanges of 25 mm and is placed with a pistol-grip delivery system which allows controlled release and recapturing, if needed. The braided construction and the silicone encasement of the stent mesh allows for a higher expansion force than the Ultraflex ® , making it ideal for placement in strictures with a large tumor bulk or surrounding fibrosis in the mid-esophagus [26, 45] (Fig. 4).…”

“…In the braided stents, the nitinol wires cross over each other but do not interlock. They have a high radial force and, although being more flexible, that configuration retains a relativity high axial force specially when coated, due to the restriction of the movement of the wires by the silicone dipping, heightening the risk of kinking on flexion [26]. In addition, braided stents shorten significantly upon expansion, thus being less predictable when deployed.…”

“…These stents have an internal and external silicone coating in order to prevent ingrowth and recurrent dysphagia. The internal stent cover also precludes adherence of fibrous food to the stent The braided construction and the silicone encasement of the stent mesh allows for a higher expansion force than the Ultraflex ® , making it ideal for placement in strictures with a large tumor bulk or surrounding fibrosis in the mid-esophagus [26,45] (Fig. 4).…”

A viewpoint on material and design considerations for oesophageal stents with extended lifetime

“…7a). Braided stents have a high radial expansive force whilst also retaining flexibility [71]. The wires are free to move across each other at their points of contact, allowing the stent to conform during muscle contractions in the oesophagus [33,72].…”