Stent with atraumatic spacer

Abstract

To provide an implantable state with an atraumatic spacer member.SOLUTION: A stent comprises a tubular body formed of one or more interwoven wires. The tubular body includes both ends of a first open end and a second open end, and a lumen extending between both ends. The stent further comprises a first anchor member disposed adjacent to the first open end and a second anchor member disposed adjacent to the second open end, the first and second anchor members respectively extend radially outward from the tubular body, and the first and second anchor members respectively have an outer diameter larger than an outer diameter of the tubular body disposed between the first anchor member and second anchor member. A plurality of spacer members is disposed around the first open end and extend longitudinally beyond the first open end, where when pulling force is applied to the spacer members, the outer diameter of the tubular body is not reduced.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to devices, methods and systems for implanting a stent, more particularly, to an implantable stent having an atraumatic spacer member. [Background technology]

[0002] An intraluminal prosthesis is a medical device used to treat lumens within the body. One type of intraluminal prosthesis used to repair and / or treat various vascular diseases is a stent. Stents are generally longitudinal tubular devices formed of biocompatible materials and are useful for opening and supporting various lumens within the body. For example, stents can be used in the vascular system, genitourinary tract, gastrointestinal tract, esophagus, trachea / bronchi and bile duct, as well as a variety of other applications within the body.

[0003] Metallic stents adjacent to the lumen are also used to drain accumulations of pancreatic fluid and to provide direct drainage for the bile duct or gallbladder. When metallic stents are placed adjacent to the wall of a cyst, acute bleeding may occur as drainage reduces the volume of the cyst and the distal face of the stent comes into contact with the cyst wall. Stent ends, such as multi-pointed tips, may involve repeated interaction between the ends of the stent and the cyst wall. Thus, there remains a need to reduce or eliminate this tissue interaction to eliminate bleeding when endoluminal prostheses such as stents are used for drainage. Summary of the Invention

[0004] The present disclosure relates to various embodiments of stents, such as braided stents, having integral spacer features. A first exemplary stent includes a tubular body formed of one or more interwoven wires and having opposite ends, a first open end and a second open end, and a lumen extending between the opposite ends, the tubular body defining a longitudinal axis extending between the first open end and the second open end, a first anchor member disposed adjacent the first open end and a second anchor member disposed adjacent the second open end, the first anchor member and the second anchor member respectively extending radially outward from the tubular body and having an outer diameter larger than an outer diameter of the tubular body disposed between the first anchor member and the second anchor member, and a plurality of spacer members disposed around the first open end and extending longitudinally beyond the first open end, wherein when a tensile force is applied to the spacer members, the outer diameter of the tubular body is not reduced.

[0005] Alternatively or additionally to any one of the above examples, the spacer members each have a first leg and a second leg extending along a portion of the tubular body toward the second open end. Alternatively or additionally to any one of the above examples, the spacer member extends radially outward beyond an outer diameter of the tubular body.

[0006] Alternatively or additionally to any one of the above examples, the spacer members are each formed from a single wire loop. Alternatively or additionally to any one of the above examples, the spacer member is formed separately from the tubular body and attached to an inner wall of the tubular body.

[0007] Alternatively or additionally to any one of the above examples, the spacer members are interwoven with the tubular body. Alternatively or additionally to any one of the above examples, the spacer member is less flexible than the tubular body.

[0008] Alternatively or in addition to any one of the above examples, the plurality of spacer members includes a first group of spacer members having a first length and a second group of spacer members having a second length that is shorter than the first length.

[0009] Alternatively or additionally to any one of the above examples, the first group of spacer members are more flexible than the second group of spacer members. Alternatively or additionally to any one of the above examples, the stent may further include a covering extending over the tubular body, the first and second anchor members, and the plurality of spacer members.

[0010] Alternatively or additionally to any one of the above examples, at least one spacer member has variable flexibility along its length. Alternatively or additionally to any one of the above examples, at least one spacer member is formed of a tapered wire having a first thickness in a first region adjacent the tubular body and a second thickness in a second region disposed furthest from the tubular body.

[0011] Alternatively or additionally to any one of the above examples, the second thickness is less than the first thickness such that the second region is more flexible. Alternatively or additionally to any one of the above examples, the first and second anchor members extend perpendicular to the longitudinal axis.

[0012] Alternatively or additionally to any one of the above examples, the stent may further include a retrieval element disposed at the second open end. Another example stent includes a tubular body formed of one or more interwoven wires, the tubular body having opposite ends, a first open end and a second open end, and a lumen extending between the opposite ends, the tubular body defining a longitudinal axis extending between the first open end and the second open end, a first group of spacer members disposed about the first open end and extending radially outward beyond an outer diameter of the tubular body, the first group of spacer members having a first length, and a second group of spacer members disposed about the first open end and extending longitudinally beyond the first open end, the second group of spacer members having a second length shorter than the first length, wherein when a tensile force is applied to the first and / or second spacer members, the outer diameter of the tubular body is not reduced.

[0013] Alternatively or additionally to any one of the above examples, a first anchor member disposed adjacent the first open end and a second anchor member disposed adjacent the second open end, the first anchor member and the second anchor member each extending radially outward from the tubular body, and the first anchor member and the second anchor member each having an outer diameter greater than an outer diameter of the tubular body disposed between the first anchor member and the second anchor member.

[0014] Alternatively or additionally to any one of the above examples, the first group of spacer members are more flexible than the second group of spacer members. Alternatively or additionally to any one of the above examples, at least one spacer member of the first or second group of spacer members is formed of a tapered wire having a first thickness in a first region adjacent the tubular body and a second thickness in a second region furthest from the tubular body, the second thickness being less than the first thickness such that the spacer member is more flexible in the second region.

[0015] Another example is a method of draining a cyst comprising implanting a stent within a wall of tissue, the stent having a first open end disposed within the cyst and a second open end disposed outside the cyst, the stent being formed of one or more interwoven wires, a tubular body defining a lumen extending between the first open end and the second open end, the stent including a plurality of spacer members disposed about the first open end and extending longitudinally beyond the first open end, draining fluid from the cyst through the lumen of the stent, and as the cyst is drained, the wall of the cyst comes into contact with one or more of the plurality of spacer members, and the plurality of spacer members prevents the wall of the cyst from contacting the first open end of the stent.

[0016] The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following figures and detailed description more particularly exemplify some of the above embodiments.

[0017] The drawings are not necessarily to scale, and like reference characters denote like elements in different drawings. The drawings illustrate various embodiments of the present application by way of example, and not by way of limitation. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a side view of a conventional stent placed adjacent to the wall of the cyst. [Diagram 2] FIG. 2 is a side view of a hollow tubular stent adjacent to the wall of a cyst according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is an end view of the stent of FIG. 2. [Figure 4] FIG. 2 is an end view of a stent according to another embodiment of the present disclosure. [Diagram 5] 3 is a perspective view showing an end of the stent of FIG. 2 positioned within a tissue structure. [Figure 6A] 1 is a partial cross-sectional side view of a stent according to another embodiment of the present invention implanted in a target tissue structure. [Figure 6B] 1 is a partial cross-sectional side view showing a stent according to another embodiment of the present invention implanted in a target tissue structure. [Figure 7] FIG. 2 is a side view of a stent according to yet another embodiment of the present invention. [Figure 8] 8 is a perspective view of the end of the stent of FIG. 7 within a tissue structure. [Figure 9] FIG. 2 is a side view of a stent according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] While the disclosure is susceptible to various modifications and alternative forms, certain of which have been shown in the drawings and described in detail for purposes of illustration. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

[0020] For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. All numerical values ​​herein, whether expressly stated or not, are intended to be modified by the term "about." The term "about" generally refers to a range of numerical values ​​that one of ordinary skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term "about" may include multiple numbers that are rounded to the nearest significant figure.

[0021] The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is used generally in its sense including "and / or" unless the content clearly dictates otherwise.

[0022] It should be noted that references herein to "an embodiment," "some embodiments," "another embodiment," and the like indicate that the described embodiment may include one or more particular features, structures, and / or characteristics. However, such references do not necessarily imply that all embodiments include the particular feature, structure, and / or characteristic. Furthermore, if a particular feature, structure, and / or characteristic is described in connection with one embodiment, it should be understood that such feature, structure, and / or characteristic may be used in connection with another embodiment, whether or not expressly stated, unless clearly stated to the contrary.

[0023] The following detailed description should be read with reference to the drawings, in which similar structures in different drawings are numbered the same, and in which the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

[0024] 1 shows a conventional woven stent 5 positioned adjacent to a tissue wall, such as a cyst wall 40. As the cyst volume is reduced by drainage through the stent lumen, the ends 7 of the stent 5 may contact the cyst wall 4, causing tissue irritation with associated bleeding and vascular infection. Additionally, premature contact of the device ends with the tissue wall may result in blockage of the device lumen, leaving residual pockets of cyst fluid unable to be effectively drained.

[0025] 2 shows a stent 10 including a tubular body 20 and a plurality of atraumatic spacer members 30 extending beyond the ends of the tubular body 20. The tubular body 20 is a hollow tubular structure with an open first end 22, an open second end 24, and a lumen extending between the ends. The tubular body 20 may be formed of one or more wires 15. The wires 15 may be woven, braided, wound, knitted, and combinations thereof to form the tubular body 20.

[0026] Stent 10 may include multiple wires 15 of a metallic material, such as, for example, Nitinol, or a material containing Nitinol, or other nickel-titanium alloy. In some cases, wires 15 may have a diameter of, for example, about 0.011 inches (about 0.28 mm). The number and diameter of wires 15 shown in FIG. 2 are not limiting and may be the same or different, and other numbers of wires 15 and wires of other diameters may be suitably used. Desirably, an even number of wires 15, for example, from about 10 to about 36, may be used.

[0027] Desirably, wire 15 is formed from any suitable implantable material, including, but not limited to, nitinol, stainless steel, cobalt-based alloys such as Elgiloy®, platinum, gold, titanium, tantalum, niobium, polymeric materials, and combinations thereof. Useful, non-limiting examples of polymeric stent materials include poly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), poly(glycolide) (PGA), poly(L-lactide-co-D,L-lactide) (PLLA / PLA), poly(L-lactide-co-glycolide) (PLLA / PGA), poly(D,L-lactide-co-glycolide) (PLA / PGA), poly(glycolide-co-trimethylene carbonate) (PGA / PTMC), polydioxanone (PDS), polycaprolactone (PCL), polyhydroxybutyrate (PHBT), poly(phosphazene) poly(D,L-lactide-co-caprolactone) (PLA / PCL), poly(glycolide-co-caprolactone) (PGA / PCL), poly(phosphate esters), and the like. Wires made of polymeric materials may also contain radiopaque materials, such as metal-based powders, particles, or pastes, that can be incorporated into the polymeric material. For example, the radiopaque material may be blended with the polymer composition from which the polymeric wire is formed and then shaped into the stent 10 as described herein. Alternatively, the radiopaque material may be applied to the surface of the metallic or polymeric wire 15 of the stent 10. In any embodiment, various radiopaque materials and their salts and derivatives may be used, such as, but not limited to, bismuth, barium, and salts of barium sulfate, tantalum, tungsten, gold, platinum, titanium, and the like. Additional useful radiopaque materials are disclosed in U.S. Pat. No. 6,626,936, the contents of which are incorporated herein by reference. Metal complexes useful as radiopaque materials are also contemplated. The stent may be selectively radiopaque in desired areas along the wire or may be completely radiopaque.

[0028] In some cases, the wire 15 has a composite structure having an inner core of tantalum, gold, platinum, tungsten, iridium, or combinations thereof, and an outer member or layer of Nitinol to provide a composite wire for improved radiopacity and visibility. In one example, the inner core is platinum and the outer layer is Nitinol. The platinum inner core comprises at least about 10% of the wire 15 based on a percentage of the total cross section. Additionally, Nitinol that has not been treated for shape memory, such as by heating, forming, and cooling Nitinol in its martensite and austenite phases, is also useful as the outer layer. Further details of such composite wires are disclosed in U.S. Pat. No. 7,101,392, the contents of which are incorporated herein by reference. The wire 15 is formed from Nitinol or a composite wire having a central core of platinum and an outer layer of Nitinol. Additionally, if required by welding processes such as MIG, the filler weld material can also be formed from Nitinol, stainless steel, cobalt-based alloys such as Elgiloy, platinum, gold, titanium, tantalum, niobium, and combinations thereof.

[0029] The tubular body 20 has one or more anchor members 26, 28 adjacent the first and second ends, respectively. The anchor members 26, 28 extend radially outward from the tubular body 20 and form flanges. In the example shown in Figure 2, the anchor members 26, 28 extend circumferentially and radially outward from the tubular body 20 generally perpendicular to the longitudinal axis X of the stent 10. The anchor members 26, 28 have an outer diameter that is greater than the outer diameter of the stent body portion disposed between the anchor members 26, 28.

[0030] The stent 10 includes a plurality of atraumatic spacer members 30 disposed around the first end 22 of the tubular body as shown in FIG. 2. In another embodiment, the plurality of spacer members 30 are disposed around both the first end 22 and the second end 24. The spacer members 30 are configured to hold the first end 22 of the stent away from the wall 40 of the cyst as the cyst is drained and the wall 40 of the cyst advances toward the first end 22. The spacer members 30 prevent the wall of the cyst 40 from contacting the first end 22 of the tubular body 20 of the stent 10. Even if the cyst is completely drained, the spacer members 30 prevent contact between the wall of the cyst and the first end 22 of the tubular body 20, thus preventing damage to the tissue wall from contacting the exposed first end 22 of the stent. In some cases, the spacer members 30 are formed from the wire 15 that forms the tubular body 20. For example, the spacer member 30 may be formed by extending one or more wires 15 from the first end 22 of the tubular body 20 and then weaving the wires back into the tubular body 20. Alternatively, the spacer member 30 may be formed from additional wires added to a previously formed tubular body 20. The spacer member 30 has a first region 36 disposed adjacent the first end 22 of the tubular body 20 and a terminal end 38 that is the portion of the spacer member 30 furthest from the first end 22 of the tubular body 20 measured along the length of the spacer member 30. The spacer member 30 may be formed from a biocompatible material such as the metal or polymeric materials listed above for the wires 15 of the tubular body 20. The spacer member 30 may be freestanding, cantilevered from the first end 22 of the tubular body 20, or extended from the first end 22 of the tubular body 20 while retaining its shape. However, when the spacer members 30 engage the walls of the lumen, the spacer members 30 provide insufficient radial resistance to engage the stent 10 .

[0031] In the example shown in FIG. 2, each spacer member 30 is formed from a single wire 35 formed into a loop and attached to the previously formed tubular body 20, with the ends of the wire loop defining legs 32, 34 attached to the inside surface of the tubular body 20. In another example, the spacer members 30 are formed from a single wire. The legs 32, 34 are welded to the inside of the tubular body 20. Alternatively, the legs 32, 34 may be attached with adhesive, wire wrapping, or another suitable permanent bond. In some examples, the legs 32, 34 are woven into the wire 15 of the tubular body 20. The legs 32, 34 extend from the first end 22 to the second end 24 over 25% or more, 50% or more, or 75% or more of the length of the tubular body 20. In some examples, the legs 32, 34 extend the entire length of the tubular body 20 from the first end 22 to the second end 24. The legs 32, 34 extend substantially parallel to the longitudinal axis or at an oblique angle, i.e., helical, along the inner surface of the tubular body 20. In some examples, the legs 32, 34 are juxtaposed along the wires 15, following the path of the wires 15 in the braid pattern of the stent 10.

[0032] The legs 32, 34 from one spacer member 30 overlap the legs 32, 34 of another spacer member 30 in some examples. For example, in some embodiments, the legs 32, 34 of a first spacer member 30 extend in a first helical direction along the inner surface of the tubular body 20, while the legs 32, 34 of a second spacer member 30 extend in an opposite second helical direction along the inner surface of the tubular body 20 and intersect with the legs 32, 34 of the first spacer member 30. In other examples, all of the legs 32, 34 of all spacer members 30 extend along the interior of the tubular body 20 without contacting the legs 32, 34 of another spacer member 30. For example, the legs 32, 34 of each spacer member 30 extend in the same helical direction along the interior of the tubular body 20.

[0033] The spacer members 30 are equally spaced around the circumference of the first end 22 and radiate outward in a radial direction. The spacer members 30 are spaced apart as shown in FIG. 3. Alternatively, the spacer members 30 may overlap adjacent spacer members 30 around the circumference of the first end 22. For example, each spacer member 30 may overlap adjacent spacer members 30 on either side of the spacer members 30. As shown in FIG. 3, the stent 10 includes three spacer members 30. In other embodiments, the stent 10 includes two opposing spacer members 30, or four, five, six, or more spacer members 30, equally or non-uniformly spaced around the circumference of the stent 10.

[0034] The wires 35 forming the spacer member 30 may have the same or different properties as the wires 15 forming the tubular body 20. For example, the wires 35 may have the same or different stiffness or flexibility, all of which may be adjusted based on the specific application. In some embodiments, the wires 35 forming the spacer member 30 may be stiffer than the stent wires 15 forming the tubular body 20 of the stent 10. In some examples, the wires 35 forming the spacer member 30 may be formed of a different material and / or have a different diameter than the stent wires 15. In some cases, the wires 35 forming the spacer member 30 may be stainless steel, while the stent wires 15 may be formed of a nickel-titanium alloy, such as Nitinol. The material forming the wires 35 of the spacer member may have a greater, the same, or less stiffness than the material forming the wires 15 of the tubular body 20, and / or the material forming the wires 35 of the spacer member may have a greater, the same, or less elastic modulus (Young's modulus) than the material forming the wires 15 of the tubular body 20. The choice of wire 35, 15 material, wire diameter, and pretreatment, as well as the stent configuration, are some of the factors that can be varied to achieve specific stent properties. Additionally, at least one of the spacer members 30 can be made radiopaque in various ways, for example, with a coating or finish, with a band, or as part of the stent material. Color or different finishes can also be added to the spacer members 30 to visually distinguish them from the rest of the stent wire 15.

[0035] The spacer member 30 is configured such that application of a pulling or squeezing force to the spacer member 30 does not reduce the outer diameter of the tubular body 20. In examples where the spacer member 30 is formed of additional wires attached to the preformed tubular body 20, the attachment is such that tensioning the spacer member 30 does not reduce the outer diameter of the tubular body 20. For example, the spacer member 30 may be attached to the inner surface of the tubular body 20 at the intersection of one or more wires by welding or using an adhesive to prevent the spacer member 30 from interacting with the woven or braided structure to reduce in diameter when the spacer member 30 is tensioned or compressed. In examples where the spacer member 30 is formed of one or more wires used in forming the tubular body 20, the portions of the wires forming the spacer member 30 may be stabilized relative to the tubular body 20 such that tensioning the spacer does not reduce the outer diameter of the tubular body 20. In one example, stabilization includes welding one or more of the final wire intersections at the first end 22 of the tubular body where the wires forming the spacer member 30 exit the tubular body 20. In another example, adhesive or additional wire wrapping may be used to stabilize the spacer member 30 to the tubular body 20. The spacer member 30 does not function as a retrieval element to reduce the diameter of the stent 10 for retrieval. In some examples, a separate retrieval element 80 is disposed at the second end 24 and / or the first end 22 of the tubular body 20. In the example shown in FIG. 2, the stent 10 includes a retrieval element 80 attached to the second end 24 of the tubular body 20. In some examples, the retrieval element 80 is a wire or suture that is woven into the loops of the wires 15 of the tubular body 20 at the second end 24 of the tubular body 20.

[0036] The spacer member 30 extends longitudinally beyond the first end 22 of the tubular body 20. The spacer member 30 can extend beyond the first end 22 of the tubular body 20 by a distance D. In some examples, the distance D can be 5%-50%, 10%-50%, or 5%-30% of the overall length of the tubular body 20. In some examples, the spacer member 30 can extend 8 mm-15 mm beyond the first end 22. The spacer member 30 can extend radially away from the tubular body 20 beyond the outer diameter of the tubular body 20 measured at the first end 22. In the example shown in FIGS. 2 and 3, the spacer member 30 also extends radially beyond the outer diameter of the anchor members 26, 28. For example, the spacer member 30 may extend radially outward at an angle between about 20 degrees and about 85 degrees, between about 25 degrees and about 75 degrees, between about 30 degrees and about 60 degrees, or between about 45 degrees and about 75 degrees from the longitudinal axis X of the stent 10. The angle of the spacer member 30 relative to the longitudinal axis X may be, for example, 25 degrees or more, 30 degrees or more, 35 degrees or more, 40 degrees or more, 45 degrees or more, 50 degrees or more, 55 degrees or more, 60 degrees or more, 65 degrees or more, 70 degrees or more, 75 degrees or more, 80 degrees or more, or 85 degrees or more, or another desired angle. The spacer member 30 shown in the figures is shaped as an elongated loop. In other examples, the spacer member 30 may be any desired shape, such as circular, oval, teardrop, etc. The ends 38 of the spacer member 30 may be rounded to provide an atraumatic end for engaging the wall 40 of the cyst, as shown in FIG. 3.

[0037] The spacer member 30 forms a structure with the necessary rigidity to maintain the stent 10 in a spaced-apart position from the cyst wall 40 to prevent damage to the tissue wall from contact with the first end 22 of the tubular body 20. In some examples, the flexibility of the spacer member 30 varies along its length. The spacer member 30 may be formed from a wire having a varying thickness along its length. In one example, as shown in FIG. 4, the stent 100 includes at least one spacer member 130 formed from a wire having a first thickness in a first region 136 adjacent the tubular body 120 and tapering and / or transitioning to a second thickness at a terminal end 138. As shown in FIG. 4, the second thickness is less than the first thickness, allowing for a more flexible spacer member 130 at the terminal end 138. The more flexible terminal end 138 allows the spacer member 130 to bend slightly at the terminal end 138 when contacting the cyst wall 40, reducing the possibility of tissue damage.

[0038] In some embodiments, the stent 10, 100 includes a covering 70, 170 disposed over at least a portion of the tubular body 20, 120 of the stent 10, 100. For example, the covering 70, 170 may completely cover the entire length of the tubular body 20, 120 of the stent 10, 100, with all interstices formed in the braided or woven pattern being covered by the covering 70, 170 to form a fully covered stent, preventing tissue ingrowth and fluid leakage into the lumen of the tubular body 20, 120. In another example, the covering 70, 170 may only cover a portion of the length of the tubular body 20, 120 of the stent 10, 100, forming a partially covered stent, with some interstices formed in the braided or woven pattern remaining uncovered to allow tissue ingrowth. In some cases, the spacer member 30, 130 is covered with the cover 70, 170 so that the entire stent 10, 100, including both the tubular body 20, 120 and the spacer member 30, 130, is covered with the cover 70, 170. For example, the cover 70, 170 extends across and fills the gap between adjacent sides of the loop formed by the wire forming the spacer member 30, 130, but the gap between adjacent spacer members 30, 130 is devoid of cover material, allowing fluid to flow between the spacer members 30, 130 around the ends of the stent 10, 100 and into the lumen of the stent 10, 100. In some cases, the stent 10, 100 may be dipped into a solution of silicone or another polymer to form the cover 70, 170. Alternatively, a polymeric sheet or tube may be placed around and / or within the tubular body 20, 120 to form the covering 70, 170. The covering 70, 170 may be placed on the exterior or interior surface of the tubular body 20, 120, or on both the interior and exterior surfaces of the tubular body 20, 120 to embed the stent 10, 100 in a polymeric material. The coating or covering may be a polymer covering such as polytetrafluoroethylene (PTFE), or a silicone covering, although other coverings, particularly elastomeric polymers, may also be used.Non-limiting examples of useful polymeric materials can include polyester, polypropylene, polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, and combinations and copolymers thereof.

[0039] FIG. 5 shows one end of the stent 10 of FIG. 2 embedded in a tissue portion shown as a cyst. In a method of draining the cyst, the first end of the stent 10 may be embedded in an opening in the tissue wall with the first anchor member 26, the first end 22 of the tubular body 20, and the three spacer members 30, all of which project through the tissue wall 46 into the cavity representing the cyst. The second anchor member 28 is positioned on the opposite side of the tissue wall 46 to secure the stent 10 across the tissue wall 46. The larger diameter of the first anchor member 26 holds the stent 10 in place so that the spacer member 30 is positioned within the cyst. As the cyst volume decreases as it is drained through the lumen of the stent 10, the wall of the cyst below (see FIG. 2) contacts the spacer member 30 rather than the first end 22 of the tubular body 20. The spacer members 30 prevent the walls of the cyst from contacting the first end 22 of the tubular body 20. The spacer members 30 hold the first end 22 of the tubular body 20 spaced from the walls of the cyst to allow fluid to pass around the first end 22 of the tubular body 20 between adjacent spacing members 30 and into the lumen of the tubular body 20 to drain the fluid from the cyst. Even if all of the fluid has been drained from the cyst, the walls of the cyst will be spaced from the first end 22 of the tubular body 20 by the spacer 30. This spacing may reduce or eliminate tissue irritation and resulting bleeding.

[0040] 6A and 6B show another embodiment of a stent 200 positioned through a tissue wall 46 with a first end 222 of the stent 200 positioned in a cavity of a cyst 242. The stent 200 includes a tubular body 220 and a first group of spacer members 230 having a first length extending from a first region 236 adjacent the first end 222 of the tubular body 220 to a terminal end 238 of the spacer members 230. The stent 200 includes a second group of spacer members 231 extending from a first region 237 adjacent the first end 222 of the tubular body 200 to a terminal end 239 of the spacer members 231. The second group of spacer members 231 have a second length that is shorter than the first length of the first group of spacer members 230, positioning the terminal ends 239 of the second group of spacer members 231 closer to the first end 222 of the tubular body 220 than the terminal ends 238 of the first group of spacer members 230. As fluid within the cyst 242 is drained through the lumen of the stent 200 in the direction of the arrow 260, the wall 40 of the cyst collapses and engages the terminal ends 238 of the first group of spacer members 230, as shown in FIG. 6. Then, as the cyst continues to drain and the wall 40 of the cyst advances toward the first end 222 of the tubular body 220, the first group of spacer members 230 bends or curves in the direction of the arrow 250 toward the second end 224 of the tubular body 220, allowing the terminal ends 239 of the second group of spacer members 231 to engage the wall 40 of the cyst, as shown in FIG. 6B.

[0041] The first group of spacer members 230 may be more flexible than the second group of spacer members 231, allowing the first group of spacer members 230 to bend or partially collapse when the cyst wall 40 advances toward the first end 222 of the tubular body. Similar to the spacer members 30, the first and second groups of spacer members 230, 231 may have variable flexibility along their lengths. In particular, one or both of the first and second groups of spacer members 230, 231 may have a terminal end 238 that is more flexible than a first portion 236 adjacent the tubular body 320. Similar to the stent 10, when the first and second groups of spacer members 230, 231 engage the lumen wall, the spacer members 230, 231 provide insufficient radial resistance to secure the stent 200. Similar to the spacer member 30 described above, the spacers 230, 231 are configured so that application of a tensile or compressive force to the spacer members 230, 231 will not reduce the outer diameter of the tubular body 220.

[0042] A further example of a stent 300 with a tubular body 320 and a plurality of spacer members 330 is shown in FIG. 7. In this example, the tubular body 320 is formed of one or more stent wires 315, does not include anchor members, and has a generally uniform diameter along its length. The plurality of spacer members 330 may be attached to the first end 322 of the tubular body 320, the second end 324 of the tubular body 320, or both. The spacer members 330 may be formed of the wires 315 that form the tubular body 320, or may be formed of wires 335 that are attached to the tubular body 320 after the tubular body 320 is formed. As with the stent 10 above, the wires 315 may be attached to the tubular body 320 by welding, adhesives, wire wrapping, or other suitable permanent connections. Additionally, as with the stent 10 above, the spacer members 330 are configured such that application of a pulling or squeezing force to the spacer members 330 does not cause the outer diameter of the tubular body 320 to decrease.

[0043] The wire 335 can be tapered to provide variable flexibility along the spacer member 330. For example, the wire 335 can have a first thickness in a first region 336 adjacent the tubular body 320 and taper to a second, smaller thickness in a region of the terminal end 338 of the spacer member 330 such that the terminal end 338 of the spacer member 330 is more flexible than the first region 336. This allows the terminal end 338 of the spacer member 330 to bend or curve toward the opposite end of the tubular body 320 when contacting tissue. The stiffer first region 336 holds the end of the tubular body 320 spaced from the tissue wall and allows fluid to drain around the first end 322 of the tubular body 320 and into the lumen of the stent 300. The flexibility of the distal end 338 of the spacer member 330 allows the spacer member 330 to gently engage the tissue wall beneath the stent 300, but the spacer member 330 provides insufficient radial resistance to anchor the stent 300 to the wall of the lumen extending generally parallel to the longitudinal axis. The stiffer first region 336 may provide sufficient longitudinal resistance to anchor the stent 300 positioned perpendicular to the tissue wall. FIG. 8 shows the first end 322 of the tubular body 320 extending into the opening in the tissue wall 46. In this example of the stent 300, the spacer member 330 has the dual function of retaining the stent 300 within the opening in the tissue wall 46 and spacing the first end 322 of the tubular body 320 of the stent 300 from the tissue wall as the cyst is drained.

[0044] 9 illustrates another example of a stent 400 having a tubular body 420 formed of one or more wires 415 woven, braided, knitted, or wrapped around the tubular body 420. The stent 400 includes a first group of spacer members 430 having a first length extending from a first region 437 adjacent the first end 422 of the tubular body 420 to a terminal end 438 of the spacer members 430. The stent 400 includes a second group of spacer members 431 extending from the first region 437 adjacent the first end 422 of the tubular body 420 to a terminal end 439 of the spacer members 431. The second group of spacer members 431 has a second length that is shorter than the first length of the first group of spacer members 430, and the terminal end 439 of the second group of spacer members 423 is disposed closer to the first end 422 of the tubular body 420 than the terminal end 438 of the first group of spacer members 430. The first group of spacer members 430 are more flexible than the second group of spacer members 431, allowing the first group of spacer members 430 to bend, curve, or partially collapse as the cyst drains and the tissue wall progresses toward the first end 422. In this example, the tubular body 420 does not include an anchor member and has a substantially uniform diameter along its length. The first and second groups of spacer members 430, 431 may be attached to the first end 422 of the tubular body 420, the second end 424 of the tubular body 420, or both. The spacer members 430, 431 may be formed of a wire 415 that forms the tubular body 420, or may be formed of a wire 435 that is attached to the tubular body 420 after the tubular body 420 is formed. As with the stent 10 described above, the spacer members 430, 431 are configured such that application of a tensile or compressive force to the spacer members 430, 431 does not cause the outer diameter of the tubular body 420 to decrease. The wire 435 is tapered and has variable flexibility along the spacer members 430, 431. For example, the wire 435 has a first thickness in a first region 436, 437 adjacent the tubular body 420 and tapers or transitions to a second, smaller thickness in the region of the terminal ends 438, 439 such that the terminal ends 438, 439 are more flexible than the first region 436, 437.This allows the terminal ends 438, 439 of the spacer members 430, 431 to bend toward the second end 424 of the tubular body 420 when they contact the tissue wall. The stiffer first regions 436, 437 hold the terminal ends 438, 439 of the tubular body 420 spaced apart from the tissue wall. The flexibility of the terminal ends 438, 439 of the spacer members 430, 431 allows the spacer members 430, 431 to gently engage the tissue wall beneath the stent 400, but provides insufficient radial resistance to anchor the stent 400 against the wall of the lumen that extends generally parallel to the longitudinal axis. The stiffer first regions 436, 437 provide sufficient longitudinal resistance to anchor the stent 400 perpendicularly positioned against the tissue wall.

[0045] Like stent 10, stents 100, 200, 300, and 400 include a covering similar to coverings 70, 170 described above disposed over at least a portion of the tubular body of stent 100, 200, 300, 400. For example, the covering may completely cover the entire length of the tubular body of stent 100, 200, 300, 400 forming a fully covered stent where all of the interstices formed by the braided or woven pattern are covered by the covering to prevent tissue in-growth and fluid leakage into the lumen of the tubular body. In another example, the covering may only cover a portion of the length of the tubular body of stent 100, 200, 300, 400 forming a partially covered stent where some of the interstices formed by the braided or woven pattern remain uncovered to allow tissue in-growth. In some examples, the spacer members 130, 230, 330, 430 are covered by the covering, so that the entire stent 100, 200, 300, 400 is covered by the covering, including both the entire tubular body and the spacer members 130, 230, 330, 430. For example, the covering may extend across and fill the gap between adjacent sides of the loops formed by the wire that form the spacer members 130, 230, 330, 430, but the gaps between adjacent spacer members 130, 230, 330, 430 may be devoid of covering material, allowing fluid to flow between the spacer members 130, 230, 330, 430 around the ends of the stent 100, 200, 300, 400 and into the lumen of the stent 100, 200, 300, 400.

[0046] Various types of stents and stent structures can be used for the stents 10, 100, 200, 300, 400. For example, the stents 10, 100, 200, 300, 400 can be self-expanding or balloon-expanding stents. The stents 10, 100, 200, 300, 400 can be radially contracted to a compressed or contracted configuration for delivery and then expandable to an expanded configuration during deployment in a body lumen. Thus, the stents 10, 100, 200, 300, 400 can be described as radially expandable or deformable. Self-expanding stents include those that have a spring-like action that causes the stent to expand radially, or those that expand due to memory properties of the stent material to assume a particular configuration at a particular temperature. The configuration of the stent can also be selected from many shapes. For example, a wire stent can be fixed into a continuous helical pattern, with or without wavy or zigzag wires, to form a radially deformable stent. Individual ring or circular members can be connected by welding or interlacing or locking struts, sutures, rings, etc. to form a tubular stent. In another embodiment, the stents 10, 100, 200, 300, 400 can be formed as a monolithic tubular member by etching or cutting a pattern of interconnected struts from a tube.

[0047] It will be understood that the present disclosure is in many respects merely illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps, without departing from the scope of the present disclosure. This includes, where appropriate, using features of one illustrative embodiment that are used in other embodiments. The scope of the invention is, of course, defined in the language of the appended claims.

Claims

1. a tubular body formed from one or more interwoven wires defining a plurality of wire crossings, the tubular body having a first open end, a second open end opposite the first open end, and a lumen extending between the first and second open ends; a first anchor member disposed adjacent the first open end and a second anchor member disposed adjacent the second open end, the first anchor member and the second anchor member extending radially outward from the tubular body and having an outer diameter greater than an outer diameter of the tubular body disposed between the first anchor member and the second anchor member; a plurality of spacer members disposed about and extending longitudinally beyond the first open end, the plurality of spacer members being attached to one or more of the plurality of wire crossings; Equipped with A stent in which the outer diameter of the tubular body does not contract when tension is applied to the spacer member.

2. The stent of claim 1 , wherein the spacer members each have a first leg and a second leg extending along a portion of the tubular body toward the second open end.

3. The stent of claim 1 or 2, wherein the spacer members extend radially outwardly beyond an outer diameter of the tubular body.

4. The stent of any one of claims 1 to 3, wherein each of the spacer members is formed from a single wire loop.

5. The stent according to any one of claims 1 to 4, wherein the spacer member is formed separately from the tubular body and attached to an inner wall of the tubular body.

6. The stent of any one of claims 1 to 4, wherein the spacer member is interwoven with the tubular body.

7. The stent according to any one of claims 1 to 6, wherein the spacer member is less flexible than the tubular body.

8. The stent of any one of claims 1 to 7, wherein the spacer members include a first group of spacer members having a first length and a second group of spacer members having a second length that is shorter than the first length.

9. The stent of claim 8 , wherein the first group of spacer members are more flexible than the second group of spacer members.

10. The stent of any one of claims 1 to 9, further comprising a cover extending over the tubular body, the first and second anchor members, and the spacer member.

11. The stent of any one of claims 1 to 10, wherein at least one of the spacer members has variable flexibility along its length.

12. 12. The stent of claim 11, wherein the at least one spacer member is formed from a tapered wire having a first thickness in a first region adjacent the tubular body and a second thickness in a second region disposed furthest from the tubular body.

13. 13. The stent of claim 12, wherein the second thickness is less than the first thickness, thereby providing greater flexibility in the second region.

14. The stent of any one of claims 1 to 13, wherein the tubular body defines a longitudinal axis extending between the first open end and the second open end, and the first and second anchor members extend perpendicular to the longitudinal axis.

15. The stent of any one of claims 1 to 14, further comprising a retrieval element disposed at the second open end.

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