Importance

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Abstract

A secure stent for maintaining a lumenal opening constructed preferably as a tubular structure of NiTi material or bioabsorbable polymers. The circumference of the tube is preferably in the shape of a polygon in contrast to the circular or oval shape of a body lumen into which the stent is to be placed. The polygon shape and ribs provides interference with the lumen wall and resists stent migration. The diameter of the stent tube is configured with each end enlarged providing flanges for interference with a lumen wall. The central portion of the stent is also bulged out to an increased diameter to provide an enhanced lumen wall resistance to avoid migration. In addition, the locking feature of a ribbed structure prevents the stent from collapsing, and thereby maintains the lumen opening. The stent is preferably constructed from polymers, including bioabsorbable polymers, and/or super elastic materials. The bioabsorbable polymer construction aids removal by causing the tube diameter to collapse. Removal of the stent can therefore be accomplished by simply grasping the proximal end of the stent. Alternatively, a stent constructed entirely of bioabsorbable material will eventually be entirely absorbed, avoiding the need for removal. Alternatively, the stent can be preferably constructed of NiTi or other shape memory material and set in the desired shape at a high temperature. Installation is accomplished by cooling the stent to the malleable Martensite state and winding it on a small diameter mandrel of an insertion/removal tool. The compacted stent is then placed in a probe and inserted in a body lumen, whereupon it is heated to an Austenite state where it regains its spring tension, forcing it back toward the set shape. Removal is accomplished by cooling the stent to the malleable Martensite state and pulling it out. If the selected material is bioabsorbable, the stent generally does not have to be removed.

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First Claim