Medical stents for body lumens exhibiting peristaltic motion

Claim 2

A unitary stent for providing reinforcement to a selected region of a selected body lumen, comprising: a resilient cylindrical supporting mesh inner layer; a resilient cylindrical retaining mesh outer layer of inner diameter about equal to the outer diameter of said inner layer; and a semi-permeable compliant membrane sandwiched between and secured in position by said supporting mesh inner layer and said retaining mesh outer layer, to form said unitary stent, said semipermeable membrane being sufficiently impermeable to prevent ingrowth of cells into said stent.

Claim 3

The stent of claim wherein said membrane is composed of expanded polytetrafluoroethylene.

Claim 4

The stent of claim 1 wherein said inner and outer layers are knitted of metal wire such that said stent is self-expandable.

Claim 5

The stent of claim 3 wherein said metal wire is nitinol wire.

Claim 6

The stent of 3 wherein said metal wire has a diameter of about 0.15 mm.

Claim 7

The stent of 3 wherein said metal wire has a diameter of about 0.15 mm.

Claim 8

The stent of claim 1 wherein said stent has a diameter of about 14 to 25 mm and a length of about 5 to 15 cm.

Claim 9

The stent of claim 1 wherein said stent has a diameter of about 8 to 10 mm and a length of about 4 to 8 cm.

Claim 10

The stent of claim 1 wherein said stent has a diameter of about 6 to 10 mm and a length of about 2 to 10 cm.

Claim 11

The stent of claim 1 wherein said stent has a diameter of about 10 to 20 mm and a length of about 2 to 6 cm.

Claim 12

The stent of claim 1 wherein said stent has a diameter of about 8 to 12 mm and a length of about 2 to 6 cm.

Claim 13

The stent of claim 1 wherein said stent has a diameter of about 10 to 20 mm and a length of about 4 to 10 cm.

Claim 14

The stent of claim 1 wherein said stent has a diameter of about 12 to 25 mm and a length of about 4 to 10 cm.

Claim 15

The stent of claim 1 wherein said stent has a diameter of about 6 to 8 mm and a length of about 2 to 6 cm.

Claim 16

The stent of claim 1 wherein said stent has a diameter of about 8 to 14 mm and a length of about 4 to 8 cm.

Claim 17

The stent of claim 1 wherein said stent has a diameter of about 8 to 25 mm and a length of about 1 to 8 cm.

Claim 18

The stent of claim 1 wherein said stent has a diameter of about 8 to 20 mm and a length of about 1 to 25 cm.

Claim 19

The stent of claim 1 wherein said lumen has a wall that is subject to peristaltic motion in which localized radial contraction of the lumen progresses in a wave-like manner along the lime, said lumen characteristically exhibiting transient localized lengthening of the lumen wall in an amount that conforms to a profile of the peristaltic contraction wave, and wherein said inner and outer layers are 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 (ε) defined by the ratio ε=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, 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.