Medical stents for body lumens exhibiting peristaltic motion

A method for providing reinforcement to a selected region of a selected body lumen having a wall that is subject to characteristic peristaltic motion in which a localized radial contraction of the lumen progresses in a wave-like manner down the lumen, said lumen, because of said peristaltic motion, characteristically exhibiting transient localized lengthening of the lumen wall in an amount that conforms to a profile of the peristaltic contraction wave, the method comprising the steps of:

• selecting for use in said lumen a tubular structural stent formed of a filament extending in a pattern of axially adjacent interlocked loops, the pattern and arrangement of said loops selected such that from a relaxed state of said loops, each of said loops is permitted to shift in the axial direction of the stent relative to and independently of loops distal thereof and proximal thereto, to permit transient localized lengthening of the stent with localized lengthening of corresponding portions of said lumen wall, the amount of said permitted shifting of said loops being sufficient to accommodate said wave profile without disturbing loops that engage other, at-rest portions of the lumen wall distal of and proximal to said wave profile, said shifting to permit localized stent lengthening being accommodated by bending of said filament, said permitted localized stent lengthening being by a factor (.epsilon.) defined by the ratio .epsilon.=l/s, where l is the maximum extended length of said portion of said lumen that corresponds to said wave profile during contraction and s is the wall length of that portion of said lumen when at rest;
• delivering said selected stent into said body lumen;
• and
• positioning said stent in contact with said wall at said selected region in said body lumen;
• whereby said stent can locally lengthen and shorten with the physiologic motions of said body lumen during peristalsis and thereby resist migration from said selected region.