Covered biliary stent with retractable antimigration features

Abstract

A stent having a tubular member formed by a first wire and a loop formed a by second wire. The tubular member is formed from the first wire. The first wire is woven to form a mesh, and the mesh has a plurality of cells. The second wire that forms the loop includes a first portion having a retrieval portion and a second portion having at least one antimigration feature.

Description

COVERED BILIARY STENT WITH RETRACTABLE ANTIMIGRATION FEATURESINTRODUCTION

[0001] The present disclosure relates to a stent for placement in a body lumen and more particularly to stents having antimigration features to prevent or hinder the unintended dislocation or migration of the stent in the body lumen.

[0002] As is well known to those skilled in the art, stents are designed to provide passage for digested material, blood and other fluid to flow, and thus, restoring proper function of a diseased body lumen having strictures, for example. Additionally, stents can be endoscopically placed or inserted. Stents are usually placed in the body lumen transluminally through an endoscope or placed within the body percutaneously. Stents may be placed in body lumens such as, for example, the esophageal tract, the gastrointestinal (Gl) tract, the tracheobronchial tract, urinary tract, biliary tract, vascular system, etc. In the biliary tract, stents are used to treat diseases such as intraoperative injury, pancreatic and enocarcinoma, and cholangiocarcinoma.

[0003] Complications arising from the use of stents include full stent migration, which is a condition whereby the stent moves from an originally deployed location such that no portion of the stent is in the originally deployed location; partial stent migration, which is a condition whereby the stent moves from the originally deployed location such that a portion of the stent remains in the originally deployed location. Furthermore, the moist and lubricious environment of the body lumen reduces friction between the wall of the body lumen and the outer surface of the stent, which promotes stent migration. Stentmigration may be caused by forces experienced by the stent during use in the body lumen, post deployment. For example, stents that are designed to be placed in the gastrointestinal tract may tend to migrate due to fluid pressure from bile flowing through the biliary tract or from peristalsis, which is involuntary constriction and relaxation of the muscles in the esophagus, intestine and colon.

[0004] Some stents are designed with features such as barbs, wide flanges / flared ends to prevent stent migration. In some instances, the stent may be designed to radially expand during deployment into the body lumen. However, in some instances, the stent may experience compressive forces in the body lumen that causes the stent to migrate. Furthermore, stents may be designed to include exposed metal portions of the stent to promote tissue ingrowth into the interstices or openings thereof, and thus anchoring the stent and reducing the risk of stent migration. Such tissue ingrowth may make the stent more difficult to remove or reposition when the tissue has anchored the stent in the body lumen. One method to limit tissue ingrowth may include covering a portion of the stent, thereby reducing the surface area of the stent available to anchor the stent. However, reducing the surface area makes the stent susceptible to migration.

[0005] Other complications associated with current stent designs include removability issues such as stent breakage, bleeding around the stent deployment site, cholangitis, stent obstructions and partial intestinal obstruction.

[0006] Thus, while current stents achieve their intended purpose, there is a need for a new and improved stent that has improved antimigrationfeatures that mitigate stent movement and that are configured to allow the stent to more easily be removed from the body lumen.SUMMARY

[0007] According to several aspects, a stent for placement in a body lumen includes a tubular member that has a proximal end and a distal end. The tubular member is formed from a wire. The wire is woven to form a mesh. The mesh defines a lumen. A first wire loop is formed from the wire of the tubular member and the first wire loop has a first portion, a second portion and a third portion. The first portion of the first wire loop extends radially outward from the tubular member to a first portion extended position. The first portion of the first wire loop has a first end connected to the mesh and a second end. The second portion of the first wire loop has a first end connected to the second end of the first portion and a second end. The third portion of the first wire loop extends radially outward from the tubular member to a third portion extended position. The third portion of the first wire loop has a first end connected to the second end of the second portion of the first wire loop and a second end connected to the mesh. Application of a tensile force on the second portion of the first wire loop causes the first and third portions of the first wire loop to retract from the first and third extended positions to extract the stent from the body lumen.

[0008] In another aspect of the present disclosure, the stent further includes a second wire loop formed from the wire of the tubular member disposed remote from the first wire loop and having a fixed size and shape.

[0009] In another aspect of the present disclosure, the second wire loop extends radially outward from the tubular member and is inclined toward the proximal end of the tubular member.

[0010] In another aspect of the present disclosure, the stent further includes a third wire loop formed from the wire of the tubular member disposed remote from the first wire loop and opposing the second wire loop and having a fixed size and shape.

[0011] In another aspect of the present disclosure, the first portion of the first wire loop extends radially outward from the tubular member and is inclined toward the distal end of the tubular member.

[0012] In another aspect of the present disclosure, the second portion of the first wire loop is threaded through the mesh of the tubular member and disposed in the lumen defined by the mesh of the tubular member.

[0013] In another aspect of the present disclosure, the stent further includes a third wire loop disposed at the distal end of the tubular member.

[0014] In another aspect of the present disclosure, the mesh of the tubular member is coated with silicone between the proximal end and the distal end of the tubular member.

[0015] In another aspect of the present disclosure, the coating of silicone further comprises a portion of the coating that extends radially outward of the tubular member and receives the first portion of the first wire loop in the extended position.

[0016] In another aspect of the present disclosure, the first wire loop is made of a shape set material. For example, the shape set material is nitinol.The shape set material is preformed in the shape of a loop to form the first and third portions of the first wire loop.

[0017] According to several aspects, a stent for placement in a body lumen includes a tubular member having a proximal end and a distal end. The tubular member is formed from a first wire. The first wire is woven to form a mesh with cells. Additionally, the stent includes a wire loop formed by a second wire. The wire loop has a first portion and a second portion. The first portion of the wire loop includes a retrieval portion, and the second portion includes antimigration features. The antimigration features extend radially outward from the tubular member to an extended position. The retrieval portion is engageable to retract the antimigration features from the extended position. Additionally, and more specifically, applying a tensile force on the retrieval portion of the wire loop causes the antimigration features to retract from the extended position to extract the stent from the body lumen.

[0018] In yet another aspect of the present disclosure, the stent includes an outer cover layer disposed at least partially over the tubular member between the proximal end and distal end of the tubular member.

[0019] In yet another aspect of the present disclosure, at least a portion of the outer cover layer extends radially outward and receives the antimigration features in the extended position.

[0020] In yet another aspect of the present disclosure, the second portion of the wire loop is threaded through multiple cells of the mesh of the tubular member.

[0021] In yet another aspect of the present disclosure, the antimigration features extend radially outward from the tubular member at the proximal end of the tubular member.

[0022] In yet another aspect of the present disclosure, the second portion of the wire loop is threaded through a first plurality of the plurality of cells of the mesh of the tubular member to form antimigration loops.

[0023] In yet another aspect of the present disclosure, the antimigration loops extend radially outward from the tubular member at the distal end of the tubular member.

[0024] In yet another aspect of the present disclosure, the antimigration features further include two antimigration loops each extending radially outward from the tubular member at the distal end of the tubular member.

[0025] In still another aspect of the present disclosure, the antimigration features further include antimigration loops disposed at the proximal end of the tubular member and antimigration loops disposed at the distal end of the tubular member. Additionally, the second portion of the wire loop further includes a connector portion. The connector portion connects the antimigration loops at the proximal end of the tubular member to antimigration loops at the distal end of the tubular member.

[0026] According to several aspects, a stent for placement in a body lumen includes a tubular member having a proximal end, a distal end and a diameter. The tubular member is formed from a first wire. The first wire is woven to form a mesh with cells. Additionally, the stent includes a wire loop formed by a second wire. The wire loop has a first portion and a second portion. The firstportion of the wire loop includes a retrieval portion, and the second portion includes multiple antimigration features. The antimigration features extend radially outward from the tubular member to an extended position. The retrieval portion is engageable to retract the antimigration features from the extended position. Additionally, and more specifically, applying a tensile force on the retrieval portion of the wire loop causes the antimigration features to retract from the extended position and reduces the diameter of the tubular member to extract the stent from the body lumen.

[0027] In still another aspect of the present disclosure, the stent includes an outer cover layer disposed at least partially over the tubular member between the proximal end and distal end of the tubular member.

[0028] In still another aspect of the present disclosure, a portion of the outer cover layer extends radially outward and receives the antimigration features in the extended position.

[0029] In still another aspect of the present disclosure, the antimigration features extend radially outward from the tubular member at the distal end of the tubular member.

[0030] In still another aspect of the present disclosure, the antimigration features further include two antimigration features. The first antimigration feature extends radially outward from the tubular member at the proximal end and the second antimigration feature extends radially outward from the distal end of the tubular member.

[0031] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0033] FIG. 1A is a perspective view of a fully covered stent with antimigration features at both the proximal and distal ends, in accordance with an embodiment of the present disclosure;

[0034] FIG. 1 B is a cross-section view of the fully covered stent with antimigration features at both the proximal and distal ends, as indicated in FIG.1 A, in accordance with an embodiment of the present disclosure;

[0035] FIG. 2 is a magnified partial view of the proximal end of a stent having an antimigration feature, in accordance with an embodiment of the present disclosure;

[0036] FIG. 3A is a magnified partial view of the proximal end of a stent with a woven antimigration feature, in accordance with an embodiment of the present disclosure;

[0037] FIG. 3B is a magnified partial view of the proximal end of a stent with a shape set antimigration feature, in accordance with an embodiment of the present disclosure;

[0038] FIG. 4A is a magnified partial view of a proximal end of a stent with antimigration features with a knot retracting due to a tensile force applied on the loop, in accordance to an embodiment of the present disclosure;

[0039] FIG. 4B is a magnified partial view of a proximal end of a stent with antimigration features with a set shape due to a tensile force applied on the loop, in accordance with an embodiment of the present disclosure;

[0040] FIG. 5 is a magnified partial view of a stent with fully retracted antimigration features and a cinched proximal end, in accordance with an embodiment of the present disclosure;

[0041] FIG. 6A is a magnified partial view of a stent with an outer cover that lays flat when antimigration features are fully retracted, in accordance with an embodiment of the present disclosure;

[0042] FIG. 6B is a magnified partial view of a stent with an outer coverwith a pocket that is empty when antimigration features are fully retracted, in accordance with an embodiment of the present disclosure;

[0043] FIG. 7 is a perspective view of an alternate embodiment of a stent having a wire loop having antimigration features formed from the wire that forms the mesh of the tubular member, in accordance with an embodiment of the present disclosure;

[0044] FIG. 8a is a cross-sectional view of the alternate embodiment of the stent shown in FIG. 7, in accordance with an embodiment of the present disclosure; and

[0045] FIG. 8b is a cross-sectional view of an alternate embodiment of the stent shown in FIG. 7 having three wire loops, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0046] The following description is merely exemplary in nature and not intended to limit the present disclosure, application, or uses.

[0047] The embodiments illustrated herein may be used in any portion of the body benefiting from a removable or repositionable indwelling medical device, such as a stent, including but not limited to, the gastrointestinal region, esophageal region, duodenum region, biliary region, colonic region, as well as any other bodily region or field. Additionally, the embodiments illustrated herein are not limited to the size or shapes illustrated herein. Moreover, in the present disclosure the proximal end of the stent refers to, for example, the end of the stent that is positioned nearer to the liver, while the distal end of stent refers to the end of the stent that is closer to the duodenum, where bile enters the digestive system in a biliary stent placement.

[0048] With reference to FIGS. 1 A and 1 B, a perspective view and a longitudinal cross-sectional view of a stent 100 is illustrated, in accordance with an embodiment of the present disclosure. Stent 100 has a tubular member 102 and a wire loop 104. Stent 100 is suitable for multiple applications in a body lumen. Stent 100 is particularly suitable for use in the Gl tract, including biliary and esophageal lumens.

[0049] The tubular member 102 is generally formed by a stent wire 106 that is woven or braided to create a cylindrical framework or structure. It should also be appreciated that, in some embodiments, tubular member 102 may be laser cut from a tube, e.g., a nitinol tube. The tubular member 102 has a proximal end 108, a distal end 110 and a first diameter d1 (shown in FIG.1B). Intersections formed by weaving or braiding the stent wire 106 creatediamond shaped cells 112. Alternatively, the cells 112 are a shape different from a diamond shape, for example tubular member 102 may be knitted. In an embodiment of the present disclosure the tubular member 102 is also formed by weaving or braiding multiple stent wires 106. An example of a woven tubular member 102 is described in more detail in U.S. Patent Application Publication No. 2017 / 0105854, file Oct. 20, 2015, which is hereby incorporated by reference in its entirety. Another example of a woven tubular member 102 is the Evolution® stent commercialized by Cook® Medical.

[0050] Without limitation, the stent wire 106 is made from medical grade stainless steel or from nitinol or other shape-memory materials, and / or other metals / polymers. Moreover, the stent wire 106 may have a radiopaque core such as platinum, palladium or similar material. In an embodiment of the present disclosure the tubular member 102 is a self-expanding structure, or an obstinate structure designed to resist deformation.

[0051] The tubular member 102 further includes a lumen 114 extending between the proximal end 108 and the distal end 110 and defined by the stent wire 106 and, thus, providing an interior passage for the bodily fluid traveling through the body lumen. Additionally, the stent wire 106 forming the tubular member 102 is covered at least partially with coating layer 116 to seal the cells 112 to prevent tissue ingrowth through the cells 112 of the tubular member 102. For example, the coating layer 116 covering the tubular member 102 is made from silicone, although other like materials are contemplated. In an embodiment of the present disclosure the coating layer 116 may only cover a portion of the tubular member 102.

[0052] With continuing reference to FIGS. 1 A and 1 B, the wire loop 104 is shown. The wire loop 104 includes a first portion 117 that defines a retrieval loop 118 and a second portion 119 that defines antimigration features 120a, 120b, 120c, and 120d. The retrieval loop 118 is the portion of the wire loop 104 that extends between the antimigration feature 120a and antimigration feature 120d. In the instant embodiment, the retrieval loop 118 and the antimigration features 120a and 120d are disposed at the proximal end 108 of the stent 100.

[0053] The second portion 119 of the wire loop 104 further includes a connector portion 122 that connects the first antimigration feature 120a and at the proximal end 108 to the antimigration feature 120b at the distal end 110. In another embodiment of the present disclosure the second portion 119 of the wire loop 104 has multiple connector portions 122. For example, the second portion 119 of the wire loop 104 further includes a second connector portion 122 that connects the antimigration feature 120b to the antimigration feature 120c at the distal end 110, and a third connector portion 122 that connects the antimigration feature 120c and the antimigration feature 120d.

[0054] The antimigration features 120a, 120b, 120c, 120d extend radially outwards from cells 112 of the tubular member 102. Antimigration features 120a, 120b, 120c and 120d are configured to hinder the movement or migration of the stent 100 by contacting the body lumen. In an embodiment of the present disclosure the antimigration features 120a, 120b, 120c and 120d are formed by threading the second portion 119 of wire loop 104 through a predetermined set of cells 112 at both the proximal end 108 and distal end 110 to form a readily outward extending loop, as shown FIGS. 1A and 1B (referredhereinto as an antimigration loop). In another embodiment of the present disclosure, antimigration features 120a, 120b, 120c and 120d are formed by threading the second portion 119 of the wire loop 104 through the set of the cells 112 at the proximal end 108 and at the distal end, as will be described in further detail.

[0055] Referring now to FIG. 2, a magnified perspective view of the proximal end 108 of the stent 100 is shown, in accordance with an embodiment of the present disclosure. FIG. 2 further illustrates how the antimigration feature 120a is connected to the tubular member 102 of stent 100 by weaving the second portion 119 of the wire loop 104 through multiple cells 112, namely, a first cell 112a, a second cell 112b and a third cell 112c, in accordance with the present disclosure. Moreover, FIG. 2 shows the second portion 119 of the wire loop 104, entering the lumen 114 of the tubular member 102 via the first cell 112a and exiting the lumen via the second cell 112b, reentering the lumen of the tubular member 102 via the second cell 112b and finally exiting via the third cell 112c to form antimigration feature 120a. In an embodiment of the present disclosure the second portion 119 of the wire loop 104 may be threaded through multiple sets of cells 112 in proximity of either the proximal end 108 and / or the distal end 110 (shown in FIG. 1A) to form multiple antimigration loops.

[0056] Referring now to FIG. 3A, a partial longitudinal cross-sectional view of a stent 200, as described above, having a tubular member 202 and a wire loop 204 is illustrated, in accordance with another embodiment of the present disclosure. In the present embodiment, the wire loop 204 is one continuous wire loop that includes a first portion 217 and a second portion 219.The first portion 217 of wire loop 204 defines the retrieval loop 218 and the second portion 219 defines the two antimigration features 220a and 220b. The antimigration features 220a and 220b are formed at the proximal end 208 of the tubular member 202 by threading wire loop 204 through a set of cells 212 to interlock wire loop 204 with the tubular member 202 of stent 200, as described above, in FIG. 2. Alternatively, in an embodiment of the present disclosure the retrieval loop 218 and two or more antimigration features 220 are formed at the distal end (not shown) of the tubular member of stent 200 in a like manner.

[0057] Referring to FIG. 3B, a partial longitudinal cross-sectional view a stent 300 having a tubular member 302 and a wire loop 304, as described above, in accordance with yet another embodiment of the present disclosure. In the present embodiment, the wire loop 304 is a continuous wire loop made from shape memory material, described above, and has a first portion 317 and second portion 319. The first portion 317 of the wire loop 304 defines a retrieval loop 318 and the second portion 319 of the wire loop 304 defines a set of two shape set antimigration features 320a and 320b. The wire loop 304 is threaded through cells 312a, b, c, d of the tubular member 302 to form a set of two shape set antimigration features 320a and 320b. The first shape set antimigration feature 320a is formed, for example, by threading the wire loop 304 through an exit cell 312a and an entrance cell 312b. In like manner, the second shape set antimigration feature 320b is formed by the threading the wire loop 304 through the exit cell 312c and the entrance cell 312d. In the instant embodiment, the exit cell 312a and the entrance cell 312b are adjacent cells and, similarly, the exit cell 312c and the entrance cell 312dare adjacent cells as well. Additionally, the exit cells, 312a and 312c, and the entrance cells, 312b and 312d, are separated by one or more cells.

[0058] Referring to FIG. 4A, a partial cross-sectional view of the stent 200 with the retrieval loop 218 placed under a tensile load “T” is illustrated, in accordance with an embodiment of the present disclosure. The stent 200 may be removed from a body lumen by engaging the retrieval loop 218 and applying a tensile load “T” to the retrieval loop 218. As the tensile load “T” is continuously applied to the retrieval loop antimigration features 220a, 220b retract towards the tubular member 202. The antimigration features are fully retracted when the second portion 219 of the wire loop 204 contacts the tubular member 202 of the stent 200.

[0059] Referring to FIG. 4B, a partial longitudinal cross-sectional view of the stent 300 with shape set antimigration features, 320a and 320b, and the retrieval loop 318 placed under the tensile load “T” is illustrated, in accordance with an embodiment of the present disclosure. As tensile load “T” is continuously applied to the retrieval loop 318 the shape set antimigration features 320a and 320b retract towards the tubular member 302. The antimigration features 320a and 320b are fully retracted when the second portion 319 of the wire loop 304 contacts the tubular member 302 of the stent 300.

[0060] Referring now to FIG. 5, a partial cross-sectional view of the of stent 200 with the antimigration features 220a and 220b fully retracted is illustrated, in accordance with an embodiment of the present disclosure. With the application of additional tensile load “T” on the retrieval loop 218 antimigration features 220a and 220b are fully retracted and the tubularmember 202 of the stent 200 is reduced in diameter. Advantageously for removal of stent 200, the proximal end 208 of the tubular member 202 of the stent 200 is reduced in diameter, from the first diameter d1 to a second diameter d2.

[0061] Referring now to FIGS. 6A, a partial cross-sectional view of a stent 400 with a coating layer 416 and fully retracted antimigration features 420a, 420b is illustrated, in accordance with the present disclosure. The coating layer 416, as described above with respect to other embodiments of the present disclosure, is applied to and covers the tubular member. As the antimigration features 420a and 420b are deployed and extend radially outward from the tubular member the coating layer 416 is extended outward in proportion to the extension and retraction of the antimigration features 420a and 420b. For example, as shown in FIG. 6A, the coating layer 416 lays flat on the tubular member 402 of the stent 400 when the antimigration features 420a and 420b are fully retracted.

[0062] Referring to FIG. 6B, a partial cross-sectional view of a stent 500 with a coating layer 516 and fully retracted antimigration features 520a, 520b is illustrated, in accordance with an alternative embodiment of the present disclosure. In accordance with the present embodiment the coating layer 516 includes a pocket 528 for each antimigration feature, 520a and 520b, to extend into. When the antimigration feature 520a, for example, is fully retracted the pocket 528 recedes towards the tubular member 502, as shown in FIG. 6B.

[0063] With reference to Fig. 7, a perspective view of an alternate stent 600 is illustrated, in accordance with another embodiment of the presentdisclosure. Stent 600 has a tubular body 602 having a proximal end 604 and a distal end 606. T ubular body 602 is formed of a single woven wire or multiple woven wires 608. Woven wire 608 may be covered or encapsulated, entirely or at least partially, by a layer or coating of silicone 610 or other suitable material. Silicone layer or coating 610 along with woven wire 608 define a lumen 612 through which fluid may pass.

[0064] Moreover, tubular body 602 of stent 600 further includes antimigration features 614, 616, 618, and 620 configured to inhibit movement or migration of stent 600 in a body lumen after stent 600 has been placed in the body lumen. Antimigration features 614, 616, 618, and 620, for example, are each a loop of wire formed from the woven wire 608 that defines the tubular body 602. Furthermore, antimigration features 614, 616 are of a fixed shape and size and antimigration features 618, 620 are retractable into the lumen 612 of the tubular body 602. Fixed antimigration features 614, 616 are formed from a portion of woven wire 608 and project outwardly from tubular body 602 and are not retractable into lumen 612. In other words, the weave of the tubular body 602 is interrupted to form the loop that forms the antimigration features 614, 616. For example, a first end 614a of antimigration feature 614 emanates from a first portion 622 of woven wire 608 and a second end 614b terminates at a second portion 624 of woven wire 608. Accordingly, antimigration feature 616 is formed in a similar manner. In an embodiment, of the present disclosure antimigration features 614, 616 are angled or inclined toward the proximal end 604 of stent 600 by an anglemeasured relative to a perpendicular reference line “L” that is generally perpendicular to the surfaceof the stent 600. The angle “ ” is an angle that is greater than zero degrees measured from reference line “L”.

[0065] Antimigration features 618, 620 are retractable from an extended position to a retracted position, in a similar manner as described above relative to the other embodiments of the present disclosure. As with the fixed antimigration features 614, 616, antimigration features 618, 620 are each a loop of wire formed from the woven wire 608 of tubular body 602. However, in contrast to fixed antimigration features 614, 616, one end of each of the loops or antimigration features 618, 620 are connected to each other by a central loop portion 630. In the present disclosure it is contemplated that the word connected includes attached to or integrally formed with. More specifically, a first end 618a of antimigration feature 618 emanates from (or integral with) a third portion 626 of woven wire 608 and a second end 618b is connected to the central loop portion 630 that extends into the lumen 612 of tubular body 602. The central loop portion 630 extends into the lumen 612 and may further extend longitudinally toward the distal end 606 of the stent 600 and connects to the first end 620a of the other antimigration feature 620. The second end 620b of the antimigration feature 620 connects to a fourth portion 628 of woven wire 608. In an embodiment of the present disclosure, antimigration features 618, 620 are angled or inclined toward the distal end 606 of stent 600 by an angle “a” measured relative to a perpendicular line “L’ ” that is generally perpendicular to the surface of the stent 6OO.The angle “a” is an angle that is greater than zero degrees measured from line “L’ ”. A force “F” may be applied to the central loop portion 630 to retract the antimigration features 618, 620 into the lumen 612 of the stent 600. The retraction of theantimigration features 618, 620 into the lumen 612 of the stent 600 by the application of force “F” on the central loop portion 630 facilitates extraction of the stent 600 from the body lumen. Moreover, an extraction loop 632 is provided at the distal end 606 of stent 600 to facilitate extraction of the stent 600 from the body lumen.

[0066] Referring now to Fig. 8a, a cross-sectional view of stent 600 at a location indicated in Fig. 7 is illustrated, in accordance with the present disclosure. As shown antimigration features 618, 620 may be located opposite each other and separated by an angle of approximately 180 degrees. However, the present disclosure contemplates other embodiments of the present disclosure where the antimigration features 618, 620 are separated by an angle of less than 180 degrees and other embodiments where the antimigration features 618, 620 are separated by an angle of more than180 degrees.

[0067] Referring now to Fig. 8b, a cross-sectional view of stent 600 is illustrated, in accordance with an alternate embodiment 700 of the present disclosure. In alternate embodiment 700, three antimigration features or loops 702, 704 and 706 are located approximately equal distances from each other and separated by an angle of approximately 120 degrees. In the present embodiment antimigration features 702, 704 and 706 are connected by loop portions 708 and 710. The force “F” may be applied to the loop portions 708 and 710 to retract antimigration features 702, 704 and 706. However, the present disclosure contemplates other embodiments of the present disclosure where the antimigration features 702, 704 and 706 are not equally spaced apart and are separated by an angle of less than 120 degrees and still otherembodiments where two of the antimigration features 702, 704 and 706 are separated by an angle of more than 120 degrees.

[0068] The stents described above of the present disclosure offer several advantages. For example, when treating biliary tract diseases, such as pancreatitis, pancreatic adenocarcinoma and cholangiocarcinoma, the antimigration features 120, 220, 320, 420 and 520 of the stents 100, 200, 300, 400 and 500 contact the body lumen and provide sufficient anchoring of the stent to mitigate movement of the stent within the body lumen. Additionally, since the stent wire that forms the tubular member 102 is separate from the wire loops 104, 204, 304, 404 and 504 that form the retrieval loop and the antimigration features 120, 220, 320, 420 and 520, the penstatic forces on the tubular members 102, 202, 302, 402, 502 will not cause the antimigration features to retract and allow the stent to migrate.

[0069] The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

Claims

CLAIMSWhat is claimed is:

1. A stent for placement in a body lumen, the stent comprising: a tubular member having a proximal end and a distal end, wherein the tubular member is formed from a wire, wherein the wire is woven to form a mesh, and wherein the mesh defines a lumen; anda first wire loop formed from the wire of the tubular member, the first wire loop having a first portion, a second portion and a third portion, wherein the first portion of the first wire loop extends radially outward from the tubular member to a first portion extended position and wherein the first portion of the first wire loop has a first end connected to the mesh and a second end and, wherein the second portion of the first wire loop has a first end connected to the second end of the first portion and a second end, wherein the third portion of the first wire loop extends radially outward from the tubular member to a third portion extended position, wherein the third portion of the first wire loop has a first end connected to the second end of the second portion of the first wire loop and a second end connected to the mesh; andwherein application of a tensile force on the second portion of the first wire loop causes the first and third portions of the first wire loop to retract from the first and third extended positions to extract the stent from the body lumen.

2. The stent of claim 1 , further comprising a second wire loop formed from the wire of the tubular member disposed remote from the first wire loop and having a fixed size and shape.

3. The stent of claim 2, wherein the second wire loop extends radially outward from the tubular member and is inclined toward the proximal end of the tubular member.

4. The stent of claim 2, further comprising a third wire loop formed from the wire of the tubular member disposed remote from the first wire loop and opposing the second wire loop and having a fixed size and shape.

5. The stent of claim 1 , wherein the first portion of the first wire loop extends radially outward from the tubular member and inclined toward the distal end of the tubular member.

6. The stent of claim 5, wherein the second portion of the first wire loop is threaded through the mesh of the tubular member and disposed in the lumen defined by the mesh of the tubular member.

7. The stent of claim 1 , further comprising a third wire loop disposed at the distal end of the tubular member.

8. The stent of claim 1, wherein the mesh of the tubular member further includes a coating between the proximal end and the distal end of the tubular member.

9. The stent of claim 8, wherein the coating further comprises a coating portion that extends radially outward of the tubular member and receives the first portion of the first wire loop in the extended position.

10. The stent of claim 1 , wherein the first wire loop is made of a shape set material, wherein the shape set material is nitinol and wherein the shape set material is preformed in the shape of a loop to form the first and third portions of the first wire loop.

11. A stent for placement in a body lumen, the stent comprising: a tubular member having a proximal end and a distal end, wherein the tubular member is formed from a first wire, wherein the first wire is woven to form a mesh, and wherein the mesh has a plurality of cells; anda wire loop formed by a second wire, the wire loop having a first portion and a second portion, wherein the first portion of the wire loop includes a retrieval portion, wherein the second portion includes at least one antimigration feature, wherein the at least one antimigration feature extends radially outward from the tubular member to an extended position, and wherein the retrieval portion is engageable to retract the at least one antimigration feature from the extended position; andwherein application of a tensile force on the retrieval portion of the wire loop causes the at least one antimigration feature to retract from the extended position to extract the stent from the body lumen.

12. The stent of claim 11 , wherein the second portion of the wire loop is threaded through a first plurality of the plurality of cells of the mesh of the tubular member.

13. The stent of claim 11, wherein the at least one antimigration feature extends radially outward from the tubular member at the proximal end of the tubular member.

14. The stent of claim 12, wherein the second portion of the wire loop is threaded through a first plurality of the plurality of cells of the mesh of the tubular member to form at least one antimigration loop.

15. The stent of claim 14, wherein the at least one antimigration loop extends radially outward from the tubular member at the distal end of the tubular member.

16. The stent of claim 15, wherein the at least one antimigration feature further includes two antimigration loops each extending radially outward from the tubular member at the distal end of the tubular member.

17. The stent of claim 14, wherein the at least one antimigration feature further includes at least one antimigration loop disposed at the proximal end of the tubular member and at least one antimigration loop disposed at the distal end of the tubular member, and wherein the second portion of the wire loop further includes a connector portion, wherein the connector portionconnects the at least one antimigration loop at the proximal end of the tubular member to the at least one antimigration loop at the distal end of the tubular member.

18. The stent of claim 11 , further comprising a coating layer at least partially disposed on the mesh of the tubular member between the proximal end and distal end of the tubular member, wherein a portion of the coating layer extends radially outward and receives the at least one antimigration feature in the extended position.

19. A stent for placement in a body lumen, the stent comprising: a tubular member having a proximal end and a distal end and a diameter, wherein the tubular member is formed from a first wire, wherein the first wire is woven to form a mesh, and wherein the mesh has a plurality of cells; and a wire loop formed by a second wire, the wire loop having a first portion and a second portion, wherein the first portion of the wire loop includes a retrieval portion, wherein the second portion includes a plurality of antimigration features, wherein the plurality of antimigration features extends radially outward from the tubular member to an extended position, and wherein the retrieval portion is engageable to retract the plurality of antimigration features from the extended position; andwherein application of a tensile force on the retrieval portion of the wire loop causes the plurality of antimigration features to retract from the extended position and reduces the diameter of the tubular member to extract the stent from the body lumen.

20. The stent of claim 19, wherein the plurality of antimigration features extend radially outward from the tubular member at the distal end of the tubular member.

21. The stent of claim 20, wherein the plurality of antimigration features further includes at least two antimigration features, wherein a first of the at least two antimigration features extends radially outward from the tubular member at the proximal end and a second of the at least second antimigration feature extends radially outward from the distal end of the tubular member.

22. The stent of claim 19, an outer cover layer at least partially disposed over the tubular member between the proximal end and distal end of the tubular member.

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