Patent Description:
The present disclosure pertains to medical devices, methods for manufacturing medical devices, and uses thereof. More particularly, the present disclosure pertains to a stent for implantation in a body lumen, and associated methods.

A wide variety of intracorporeal medical devices have been developed for medical use, for example, surgical and/or intravascular use. Some of these devices include guidewires, catheters, medical device delivery systems (e.g., for stents, grafts, replacement valves, etc.), and the like. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods.

<CIT> relates to a stent for a biological luminal organ, capable of expressing the expansion force only by the diameter-extending operation without requiring any post-treatment, adaptable to the extension of the diameter sufficiently to a larger size than when organized; and to provide a three-dimensional biological anchorage adaptable for forming an appropriate three-dimensional shape.

<CIT> relates to a medical prosthesis comprising a tubular framework knitted from a single strand of shape memory metal. The wire may be warp knitted or weft knitted by means of a lock stitch or tuck stitch.

This disclosure provides design, material, manufacturing method, and use alternatives for medical devices. An example medical device may include a stent.

In a first example, a stent may comprise an elongated tubular member comprising at least one knitted filament having a plurality of twisted knit stitches with intermediate rung portions extending between adj acent twisted knit stitches, the elongated tubular member configured to move between a collapsed configuration and an expanded configuration. In in the collapsed configuration the plurality of twisted knit stitches have a first profile and in the expanded configuration the plurality of twisted knit stitches have a second profile different from the first profile.

In another example, a stent may comprise an elongated tubular member comprising a plurality of longitudinal filaments extending generally along a longitudinal axis of the elongated tubular member, a first helical filament extending in a first helical direction, and a second helical filament extending in a second helical direction opposite to the first helical direction, the plurality of longitudinal filaments, first helical filament, and second helical filament overlapping to form a plurality of cell. The longitudinal filaments are intermittently helically wrapped with one of the first or second helical filaments to form a plurality of interlocking joints, the interlocking joints extending at a non-parallel angle relative to the longitudinal axis of the elongated tubular member.

In another example, a stent may comprise an elongated tubular member comprising a plurality of knitted rows, each row including a plurality of loops having a loop portion and a twisted base portion with intermediate rung portions extending between adjacent loops, the elongated tubular member configured to move between a collapsed configuration and an expanded configuration. At least some of the plurality of loops may be configured to be suspended from the twisted base portion of a loop in a preceding row.

The invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which:.

It should be understood, however, that the intention is not to limit aspects of the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

Although some suitable dimensions ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed.

The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

In some instances, it may be desirable to provide an endoluminal implant, or stent, that can deliver luminal patency in a patient with an esophageal stricture or other medical condition. Such stents may be used in patients experiencing dysphagia, sometimes due to esophageal cancer. An esophageal stent may allow a patient to maintain nutrition via oral intake during cancer treatment or palliation periods. Some stents have a woven or knitted configuration to provide good radial strength with minimal foreshortening which may be desirable in esophageal and trachea-bronchial applications as well as some post-bariatric surgery applications. However, some knitted stent designs may be difficult to constrain, especially into a coaxial delivery system and thus may be delivered using a system which may not offer a method of recapture. What may be desirable is an alternative knitted stent that is capable of delivery via a coaxial delivery system while having similar radial forces and foreshortening as previous knitted stent configurations While the embodiments disclosed herein are discussed with reference to esophageal stents, it is contemplated that the stents described herein may be used and sized for use in other locations such as, but not limited to: bodily tissue, bodily organs, vascular lumens, non-vascular lumens and combinations thereof, such as, but not limited to, in the coronary or peripheral vasculature, trachea, bronchi, colon, small intestine, biliary tract, urinary tract, prostate, brain, stomach and the like.

<FIG> illustrates a side view of an illustrative endoluminal implant <NUM>, such as, but not limited to, a stent. In some instances, the stent <NUM> may be formed from an elongated tubular member <NUM>. While the stent <NUM> is described as generally tubular, it is contemplated that the stent <NUM> may take any cross-sectional shape desired. The stent <NUM> may have a first, or proximal end <NUM>, a second, or distal end <NUM>, and an intermediate region <NUM> disposed between the first end <NUM> and the second end <NUM>. The stent <NUM> may include a lumen <NUM> extending from a first opening adjacent the first end <NUM> to a second opening adjacent to the second end <NUM> to allow for the passage of food, fluids, etc..

The stent <NUM> may be expandable from a first radially collapsed configuration (not explicitly shown) to a second radially expanded configuration. In some cases, the stent <NUM> may be deployed to a configuration between the collapsed configuration and a fully expanded configuration. The stent <NUM> may be structured to extend across a stricture and to apply a radially outward pressure to the stricture in a lumen to open the lumen and allow for the passage of foods, fluids, air, etc..

The proximal end <NUM> of the stent <NUM> may include a plurality of loops <NUM>. The loops <NUM> may be configured to receive a retrieval tether or suture interwoven therethrough, or otherwise passing through one or more of the loops <NUM>. The retrieval suture may be used to collapse and retrieve the stent <NUM>, if so desired. For example, the retrieval suture may be pulled like a drawstring to radially collapse the proximal end <NUM> of the stent <NUM> to facilitate removal of the stent <NUM> from a body lumen.

The stent <NUM> may have a knitted structure, fabricated from a single filament <NUM> interwoven with itself and defining open cells <NUM>. In some cases, the filament <NUM> may be a monofilament, while in other cases the filament <NUM> may be two or more filaments wound, braided, or woven together. In some instances, an inner and/or outer surface of the stent <NUM> may be entirely, substantially or partially, covered with a polymeric covering or coating. The covering or coating may extend across and/or occlude one or more, or a plurality of the cells defined by the struts or filaments <NUM>. The covering or coating may help reduce food impaction and/or tumor or tissue ingrowth.

It is contemplated that the stent <NUM> can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stent <NUM> to be expanded into shape when accurately positioned within the body. In some instances, the material may be selected to enable the stent <NUM> to be removed with relative ease as well. For example, the stent <NUM> can be formed from alloys such as, but not limited to, Nitinol and Elgiloy®. Depending on the material selected for construction, the stent <NUM> may be self-expanding (i.e., configured to automatically radially expand when unconstrained). In some embodiments, fibers may be used to make the stent <NUM>, which may be composite fibers, for example, having an outer shell made of Nitinol having a platinum core. It is further contemplated the stent <NUM> may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some embodiments, the stent <NUM> may be self-expanding while in other embodiments, the stent <NUM> may be expand by an expansion device (such as, but not limited to a balloon inserted within the lumen <NUM> of the stent <NUM>). As used herein the term "self-expanding" refers to the tendency of the stent to return to a preprogrammed diameter when unrestrained from an external biasing force (for example, but not limited to a delivery catheter or sheath). The stent <NUM> may include a one-way valve, such as an elastomeric slit valve or duck bill valve, positioned within the lumen <NUM> thereof to prevent retrograde flow of gastrointestinal fluids.

In some instances, in the radially expanded configuration, the stent <NUM> may include a first end region <NUM> proximate the proximal end <NUM> and a second end region <NUM> proximate the second end <NUM>. In some embodiments, the first end region <NUM> and the second end region <NUM> may include retention features or anti-migration flared regions (not explicitly shown) having enlarged diameters relative to the intermediate portion <NUM>. The anti-migration flared regions, which may be positioned adjacent to the first end <NUM> and the second end <NUM> of the stent <NUM>, may be configured to engage an interior portion of the walls of the esophagus or other body lumen. In some embodiments, the retention features, or flared regions may have a larger diameter than the cylindrical intermediate region <NUM> of the stent <NUM> to prevent the stent <NUM> from migrating once placed in the esophagus or other body lumen. It is contemplated that a transition from the cross-sectional area of the intermediate region <NUM> to the retention features or flared regions may be gradual, sloped, or occur in an abrupt step-wise manner, as desired.

In some embodiments, the first anti-migration flared region may have a first outer diameter and the second anti-migration flared region may have a second outer diameter. In some instances, the first and second outer diameters may be approximately the same, while in other instances, the first and second outer diameters may be different. In some embodiments, the stent <NUM> may include only one or none of the anti-migration flared regions. For example, the first end region <NUM> may include an anti-migration flare while the second end region <NUM> may have an outer diameter similar to the intermediate region <NUM>. It is further contemplated that the second end region <NUM> may include an anti-migration flare while the first end region <NUM> may have an outer diameter similar to an outer diameter of the intermediate region <NUM>. In some embodiments, the stent <NUM> may have a uniform outer diameter from the first end <NUM> to the second end <NUM>. In some embodiments, the outer diameter of the intermediate region <NUM> may be in the range of <NUM> to <NUM> millimeters. The outer diameter of the anti-migration flares may be in the range of <NUM> to <NUM> millimeters. It is contemplated that the outer diameter of the stent <NUM> may be varied to suit the desired application.

It is contemplated that the stent <NUM> can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stent <NUM> to be expanded into shape when accurately positioned within the body. In some instances, the material may be selected to enable the stent <NUM> to be removed with relative ease as well. For example, the stent <NUM> can be formed from alloys such as, but not limited to, Nitinol and Elgiloy®. Depending on the material selected for construction, the stent <NUM> may be self-expanding or require an external force to expand the stent <NUM>. In some embodiments, composite filaments may be used to make the stent <NUM>, which may include, for example, an outer shell or cladding made of Nitinol and a core formed of platinum or other radiopaque material. It is further contemplated the stent <NUM> may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some instances, the filaments of the stent <NUM>, or portions thereof, may be bioabsorbable or biodegradable, while in other instances the filaments of the stent <NUM>, or portions thereof, may be biostable.

<FIG> illustrates enlarged side view of the knitted configuration of the stent <NUM>. The stent <NUM> may include a plurality of rows 50a, 50b, 50c, 50d (collectively, <NUM>) extending circumferentially about the stent <NUM>. The stent <NUM> may include any number of rows <NUM> desired. For example, the number of rows <NUM> may be selected to achieve a desired length of the stent <NUM>. The uppermost, or first, row 50a may be unsecured and active. In some instances, the first row 50a may include a plurality of loops 60a, 60b, 60c (collectively, <NUM>). The loops <NUM> may each include a loop portion 62a, 62b, 62c (collectively, <NUM>) and an overlapping base portion 64a, 64b, 64c (collectively, <NUM>). The overlapping base portion 64a, 64b, 64c is understood as the portion of the loops <NUM> in which one segment of the filament overlaps or crosses over a second segment of the filament, with the segment of the filament forming the loop portion 62a, 62b, 62c extending therebetween. Adjacent loops <NUM> may be interconnected by a rung section 66a, 66b (collectively, <NUM>). For example, a first rung section 66a may extend between the base portion 64a of the first loop 60a and the second base portion 64b of the second loop 60b. The next row 50b may be suspended from the loops <NUM> of the first row 50a. For example, the second row 50b may include a plurality of loops 70a, 70b, 70c (collectively, <NUM>) each including a loop portion 72a, 72b, 72c (collectively, <NUM>) and a base portion 74a, 74b, 74c (collectively, <NUM>). Adjacent loops <NUM> may be interconnected by a rung section 76a, 76b (collectively, <NUM>). As the stent <NUM> is knitted, the loop portion <NUM> may be wrapped about the base portion <NUM> of the preceding row 50a.

It is contemplated that a single row <NUM> may be formed at a time. For example, the rows may be formed in succession with a subsequent row (e.g., row 50b) being formed after the preceding row (e.g., row 50a) has formed a complete rotation. While not explicitly shown, the loops <NUM> of the first row 50a may be wrapped about a section of the filaments <NUM> free from loops. As described herein, the loops <NUM> of the second row 50b may be wrapped about the base portion <NUM> of the loops <NUM> the preceding row 50a. For example, the filament <NUM> may be knitted such that it extends from the first rung section 76a, is wrapped about the base portion 64b of the preceding row 50a, crosses back over itself to form base section 74b and continues to the next rung section 76b. It is contemplated that the loop portion <NUM> may be positioned on a first side of the rungs 66a, 66b and on a second opposite side of the loop portion 62b. In other words, the filament <NUM> may be wound such that it extends on top of the second rung portion 66b, behind the base portion 64b, and over the first rung portion 66a before crossing over itself to form the base portion 74b of the loop 70b of the second row 50b. The reverse configuration is also contemplated in which the filament <NUM> may be wound such that it extends behind the second rung portion 66b, over or on top of the base portion 64b, and behind the first rung portion 66a before crossing over itself to form the base portion 74b of the loop 70b of the second row 50b.

The knitted structure of the stent <NUM> may allow the loop sections <NUM>, <NUM> to lengthen such that the cells <NUM> and/or loop sections <NUM>, <NUM> have a first profile when the stent <NUM> is in the expanded configuration and the second profile, different from the first profile, when the stent <NUM> is in a collapsed delivery configuration. Lengthening of the loop sections <NUM>, <NUM> may allow the cross-sectional diameter of the stent <NUM> to be reduced for delivery. To lengthen, the loops <NUM>, <NUM> use some of the length of the filament <NUM> from the rungs <NUM>, <NUM> to elongate. <FIG> illustrates a portion of the stent <NUM> in an elongated configuration. As can be seen, as the loops <NUM>, <NUM> elongate, the rung material <NUM>, <NUM> is pulled into the loop portion <NUM>, <NUM> to allow for loop elongation (e.g., in a direction along a longitudinal axis <NUM>) while the intermediate rung portion <NUM>, <NUM> is shortened. The rung material <NUM>, <NUM> may be accessible and readily subsumed into the loop portion <NUM>, <NUM> due to the twist region <NUM>, <NUM>. This may result in the stent <NUM> being constrained at lower forces allowing it to be loaded into a coaxial delivery system. It is contemplated that the knit structure of the stent <NUM> may be less subject to wire breaks due to fatigue from peristaltic motion, when compared to previous knit for stents. The softer curvature of the current knit pattern may allow the loops <NUM>, <NUM> be easily pursed by external forces which may be applied to the stent <NUM> by the anatomy.

<FIG> illustrates a side view of an illustrative stent <NUM> being formed about a mandrel <NUM>. The stent <NUM> may be similar in form and function to the stent <NUM> described above. The stent <NUM> may be formed from a single knitted strand or filament <NUM>. In general, the stent <NUM> is formed by knitting in a single direction. For example, in the embodiments illustrated in <FIG>, the strand <NUM> is knitted in a counterclockwise direction as shown at arrow <NUM>. However, it should be understood that the stent <NUM> may be formed by knitting in a clockwise direction, as desired. The strand <NUM> may follow a looped path about the mandrel <NUM> configured to form a plurality of interconnected loops.

The strand <NUM> may be manipulated (e.g., knitted) into a plurality of rows <NUM>, <NUM>, <NUM>, <NUM>, <NUM> each having a plurality of interconnected or intermeshing loops 140a-c, 142a-c, 144a-c, 146a-c, 148d-e. The stent <NUM> may include as many rows as required to form a stent <NUM> having the desired length. As described above, the loops may be loosely knit and include interconnecting intermediate rung portions such as the rung portions 152a and 152b interconnecting three loops 146d, 146c, 146b of one of the rows <NUM>. It should be understood that as the stent <NUM> is formed from a single strand <NUM>, the rows <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may not be distinct and separate rows but instead form a continuous connection with the preceding and/or following row. It is further contemplated that the stent <NUM> need not be formed from a single strand <NUM> but rather may include two or more strands knitted together. In some instances, a loop may be generally aligned with, or suspended from, a loop of the preceding row in a direction generally parallel to a longitudinal axis of the stent <NUM> (for example, circumferentially aligned along a length of the stent <NUM>). As can be seen, the loop 146b in one row <NUM> is suspended from the loop 144b in the row <NUM> above it. Thus, the loops may form axially extending columns or wales 150a-e, although this is not required.

To form the stent <NUM>, an end region <NUM> of the strand <NUM> is passed over an intermediate rung portion 152b of a preceding row <NUM>, as shown at arrow <NUM>. The end region <NUM> of the strand <NUM> may then be wrapped behind the loop 146c in a direction opposite to the general direction <NUM> of the overall knit. The end region <NUM> of the strand <NUM> may then be passed over a rung portion 152a on opposing side of the loop 146c (relative to the rung portion 152b) before being crossed over itself to complete the loop. The reverse configuration is also contemplated in which the loop passes behind the rung portions 152b, 152a and over the loop 146c. The loops 140a-c, 142a-c, 144a-c, 146a-c, 148d-e may generally take the form of a twisted knit stitch where each individual loop is twisted. It is contemplated that the twisted nature of the loops may create ridges in the outer surface of the stent <NUM>. These ridges may help secure the stent <NUM> within the body lumen.

<FIG> is a side view of an illustrative delivery system <NUM> for delivering a stent, such as the stents <NUM>, <NUM> described herein, to a target region. The delivery system <NUM> may include an outer or exterior elongate shaft or tubular member <NUM> and an inner elongate shaft or tubular member <NUM>. The inner tubular member <NUM> may be slidably disposed within a lumen of the outer tubular member <NUM>. The outer tubular member <NUM> may extend proximally from a distal end region <NUM> to a proximal end region <NUM> configured to remain outside of a patient's body. A first hub or handle <NUM> may be coupled to the proximal end region <NUM> of the outer tubular member <NUM>. The inner tubular member <NUM> may extend proximally from a distal end region <NUM> to a proximal end region <NUM> configured to remain outside of a patient's body. A second hub or handle <NUM> may be coupled to the proximal end region <NUM> of the inner tubular member <NUM>. In some instances, the distal end region <NUM> of the outer tubular member <NUM> may be configured to be atraumatic.

The outer tubular member <NUM> may include a lumen <NUM> extending from the distal end region <NUM> to the proximal end region <NUM>. The lumen <NUM> may also extend through the first handle <NUM>. The lumen <NUM> of the outer shaft <NUM> and the first handle <NUM> may be configured to slidably receive the inner shaft <NUM>. The inner tubular member <NUM> may include a lumen <NUM> extending from the distal end region <NUM> to the proximal end region <NUM>. The lumen <NUM> of the inner tubular shaft <NUM> may also extend through the second handle <NUM>. The lumen <NUM> of the inner shaft <NUM> may be configured to receive a guidewire <NUM>, as desired.

The stent <NUM> may be disposed around a portion of the inner tubular member <NUM> at or adjacent to the distal end region <NUM> thereof. When the stent <NUM> is disposed over the inner tubular member <NUM>, in a collapsed and elongated delivery configuration, the stent <NUM> may be restrained in a collapsed reduced diameter or delivery configuration by the outer tubular member <NUM> surrounding the stent <NUM>. In the collapsed configuration, the stent <NUM> may have a smaller diameter and a longer length than the expanded deployed configuration. The distal end region <NUM> of the outer tubular member <NUM> may be positioned such that the outer tubular member <NUM> surrounds and covers the length of the stent <NUM> during delivery. The outer tubular member <NUM> may have sufficient hoop strength to retain the stent <NUM> in its reduced diameter state.

<FIG> illustrates a side view of the delivery system <NUM> with the stent <NUM> in a partially deployed configuration. The delivery system <NUM> may be advanced through the gastrointestinal tract (or other body lumen), as desired. The delivery system <NUM> may be advanced with or without the use of a guidewire <NUM>. Once the stent <NUM> is positioned adjacent to the target region, the restraining forces maintaining the stent <NUM> in the radially collapsed configuration may be removed to deploy the stent <NUM>.

The stent <NUM> may be released by actuating the first handle <NUM> proximally relative to the second handle <NUM>, e.g., by pulling the first handle <NUM> proximally <NUM> while maintaining the second handle <NUM> in a fixed position. Thus, the outer tubular shaft <NUM> may be retracted proximally relative to the inner tubular shaft <NUM>. In other words, the outer tubular shaft <NUM> may be proximally retracted while the inner tubular shaft <NUM> is held stationary. As shown in <FIG>, as the outer tubular shaft <NUM> is retracted proximally <NUM> to uncover the stent <NUM>, the biasing force is removed from the exterior of the stent <NUM> and the stent <NUM> assumes its radially expanded, unbiased, deployed configuration. Once the outer tubular member <NUM> no longer covers the proximal end <NUM> of the stent <NUM>, the stent <NUM> may assume its fully deployed configuration, as shown in <FIG>. The delivery system <NUM> may then be removed from the body lumen.

<FIG> illustrates a side view of another alternative stent <NUM> having an alternative knitted configuration. The stent may include a first portion <NUM> including one or more rows <NUM>, <NUM> where a loop 208b in a row <NUM> is suspended from every loop 208a in the preceding row <NUM> in a manner similar to the stents <NUM>, <NUM> described above. The stent <NUM> may further include a second or intermediate portion <NUM> having one or more rows <NUM>, <NUM>, <NUM>, <NUM> where only every other loop <NUM> is formed. In the intermediate portion <NUM>, some or all of the loops <NUM> may be suspended from the intermediate rung portion <NUM>. In some instances, the stent may further include a third portion <NUM> including one or more rows <NUM>, <NUM> including the same number of loops <NUM> as the first portion <NUM>. Is contemplated that the intermediate portion <NUM> may result in a spiral patterns being formed as shown at dashed lines <NUM>, when the first row <NUM> include an odd number of loops. The spiral portion <NUM> may have a lower radial force than the first portion <NUM> and/or the third portion <NUM>. It is contemplated that the spiral portion <NUM> need not necessarily be positioned between the first portion <NUM> and the third portion <NUM>. For example, the stent <NUM> may include only one of the first portion <NUM> or the third portion <NUM>.

<FIG> illustrates a side view of another alternative stent <NUM> having an alternative knitted configuration. The stent may include a first portion <NUM> including one or more rows <NUM>, <NUM>, <NUM> where a loop <NUM> in a row <NUM> is suspended from every loop <NUM> in the preceding row <NUM> in a manner similar to the stents <NUM>, <NUM> described above. The stent <NUM> may further include a second or intermediate portion <NUM> having one or more rows <NUM>, <NUM>, <NUM>, <NUM> where only every other loop <NUM> is formed and every other loop <NUM> is dropped. In other words, the rows <NUM>, <NUM>, <NUM>, <NUM> in the second portion <NUM> may have fewer loops <NUM> than the rows <NUM>, <NUM>, <NUM> in the first portion <NUM>. In some instances, the stent <NUM> may further include a third portion <NUM> including one or more rows <NUM>, <NUM>, <NUM> including the same number of loops <NUM> as the first portion <NUM>. It is contemplated that the intermediate portion <NUM> may have a reduced number of loops <NUM> (relative to the first and/or third portions <NUM>, <NUM>) which may result in a region having a reduced radial force. This may be beneficial for placing the stent <NUM> in a region of the anatomy with sharper bends or to possibly afford a wider open section for drainage requirements, among other advantages. As shown in in the third portion <NUM> the dropped loop <NUM> may be picked up again, if so desired. In some instances, the stent <NUM> may end with the second portion <NUM> when it is desired for the stent <NUM> to be terminated at a section with reduced radial force. For example, the stent <NUM> may terminate with the second portion <NUM> if a softer stent end is required to reduce tissue aggravation.

<FIG> illustrates a side view of another alternative stent <NUM> having an alternative knitted configuration. The stent <NUM> may include a first portion <NUM> having a first knit pattern and the second portion <NUM> having a second knit pattern different from the first knit pattern. In some embodiments, the first portion <NUM> may be formed from one or more rows <NUM>, <NUM>, <NUM> having a stockinette stitch while the second portion <NUM> may be formed from one or more rows <NUM>, <NUM> having a twisted knit stitch as described with respect to <FIG>. It is contemplated that incorporating a hybrid of two or more knit patterns may provide a variable flexibility along a length of the stent <NUM>. This may allow the stent <NUM> to be more or less compliant with the surrounding anatomy. It is contemplated that the stent <NUM> may include any number of sections having a different knit pattern desired. For example, the stent <NUM> may include two, three, four, or more different knit patterns. It is further contemplated that the knit patterns may be arranged in any configuration desired. This may include blocks of rows having a same knit pattern alternating with other blocks of rows having a different knit pattern, alternating rows of different knit patterns, etc..

<FIG> illustrates a side view of another illustrative endoluminal implant <NUM>, such as, but not limited to, a stent. In some instances, the stent <NUM> may be formed from an elongated tubular member <NUM>. While the stent <NUM> is described as generally tubular, it is contemplated that the stent <NUM> may take any cross-sectional shape desired. The stent <NUM> may have a first, or proximal end <NUM>, a second, or distal end <NUM>, and an intermediate region <NUM> disposed between the first end <NUM> and the second end <NUM>. The stent <NUM> may include a lumen <NUM> extending from a first opening adjacent the first end <NUM> to a second opening adjacent to the second end <NUM> to allow for the passage of food, fluids, etc..

The proximal end <NUM> of the stent <NUM> may include a plurality of loops <NUM>. The loops <NUM> may be configured to receive a retrieval tether or suture interwoven therethrough, or otherwise passing through one or more of the loops <NUM>. The retrieval suture may be used to collapse and retrieve the stent <NUM>, if so desired. For example, the retrieval suture may be pulled like a drawstring to radially collapse the proximal end <NUM> of the stent <NUM> to facilitate removal of the stent <NUM> from a body lumen. In some embodiments, the loops <NUM> may take the form of cathedral or atraumatic style loop ends, as desired.

The stent <NUM> may have a braided or woven structure, fabricated from a plurality of longitudinal filaments <NUM> (extending in a direction generally parallel to a longitudinal axis <NUM> of the stent <NUM>) interwoven with a plurality of helical filaments <NUM>, <NUM> to form a plurality of open cells <NUM>. The longitudinal filaments <NUM> may be considered "warp" filaments and the helical filaments <NUM>, <NUM> may be considered "weft" filaments. As the longitudinal filaments <NUM> are interwoven with the helical <NUM>, <NUM> filaments, the longitudinal filaments <NUM> may undulate or have a sinusoidal wave shape along a length of the stent <NUM>. As will be discussed in more detail herein, the helical filaments <NUM>, <NUM> may be configured to be looped around the longitudinal filaments <NUM> in different diagonal directions. In other words, the first helical filament <NUM> may extend in a first helical (or rotational) direction and the second helical filament <NUM> may extend in a second helical (or rotational) direction opposite from the first. In some cases, the filaments <NUM>, <NUM>, <NUM> may be monofilament, while in other cases the filaments <NUM>, <NUM>, <NUM> may be two or more filaments wound, braided, or woven together. In some instances, an inner and/or outer surface of the stent <NUM> may be entirely, substantially or partially, covered with a polymeric covering or coating. The covering or coating may extend across and/or occlude one or more, or a plurality of the cells <NUM> defined by the struts or filaments <NUM>, <NUM>, <NUM>. The covering or coating may help reduce food impaction and/or tumor or tissue ingrowth.

It is contemplated that the stent <NUM> can be made from a number of different materials such as, but not limited to, metals, metal alloys, shape memory alloys and/or polymers, as desired, enabling the stent <NUM> to be expanded into shape when accurately positioned within the body. In some instances, the material may be selected to enable the stent <NUM> to be removed with relative ease as well. For example, the stent <NUM> can be formed from alloys such as, but not limited to, Nitinol and Elgiloy®. Depending on the material selected for construction, the stent <NUM> may be self-expanding (e.g., configured to automatically radially expand when unconstrained). In some embodiments, fibers may be used to make the stent <NUM>, which may be composite fibers, for example, having an outer shell made of Nitinol having a platinum core. It is further contemplated the stent <NUM> may be formed from polymers including, but not limited to, polyethylene terephthalate (PET). In some embodiments, the stent <NUM> may be self-expanding while in other embodiments, the stent <NUM> may be expanded by an expansion device (such as, but not limited to a balloon inserted within the lumen <NUM> of the stent <NUM>). As used herein the term "self-expanding" refers to the tendency of the stent to return to a preprogrammed diameter when unrestrained from an external biasing force (for example, but not limited to a delivery catheter or sheath). The stent <NUM> may be delivered to a target region within the body using a similar device to that described above with respect to <FIG> and <FIG>. The stent <NUM> may include a one-way valve, such as an elastomeric slit valve or duck bill valve, positioned within the lumen <NUM> thereof to prevent retrograde flow of gastrointestinal fluids.

<FIG> illustrates a flat layout of a portion of the illustrative stent <NUM>. As described above the stent <NUM> is formed from a plurality of elongated strands <NUM>, <NUM>, <NUM>. The strands are wires <NUM>, <NUM>, <NUM> are woven to form a pattern of geometric cells <NUM>. The sides 430a, 430b, 430c, 430d, 430e, 430f (collectively, <NUM>) of each of the cells <NUM> are defined by a series of strand lengths. Each of the sides <NUM> may be joined to an adjoining side in an intersection where two or more of the strands <NUM>, <NUM>, <NUM> are helically wrapped about each other to form interlocking joints 432a, 432b, 432c, 432d (collectively, <NUM>). For example, a first interlocking joint 432a may include a helical strand <NUM> helically wound with a first longitudinal strand 414a, a second joint 432b may include a second or different longitudinal strand 414b helically wound with another helical strand <NUM>. It is contemplated that the helical strands <NUM>, <NUM> forming the joints 432a, 432b may extend in opposite rotational directions about the circumference of the stent <NUM>. In some instances, the helical strands <NUM>, <NUM> may be separate and distinct wires, although this is not required. The third interlocking joint 432c may include the second longitudinal strand 414b helically wound with the helical strand <NUM>. In some embodiments, the helical strand <NUM> forming the first interlocking joint 432a and the third interlocking joint 432c may be the same filament which has made a complete helical rotation about a circumference stent <NUM>, although this is not required. The fourth interlocking joint 432d may include the first longitudinal strand 414a helically wound with the helical strand <NUM>. In some embodiments, the helical strand <NUM> forming the second interlocking joint 432b and the fourth interlocking joint 432c may be the same filament which has made a complete helical rotation about a circumference of the stent <NUM>, although this is not required. The longitudinal strands <NUM> and helical strands <NUM>, <NUM> may interact at the interlocking joints <NUM> such that the interlocking joints <NUM> have an angle in the range of about <NUM>° to about <NUM>°, <NUM>° to about <NUM>° or approximately <NUM>° relative to a longitudinal axis or plane of the stent <NUM>. In other words, as the helical strands <NUM>, <NUM> are helically wrapped, the interlocking joints <NUM> may have a non-parallel or non-orthogonal angle relative to a longitudinal axis or plane of the stent <NUM>.

In some embodiments, the cells <NUM> may have a generally hexagonal shape. However, the shape of the cell <NUM> may vary based on the number of interlocking joints <NUM> forming the cell <NUM>. For example, each cell <NUM> may not include four interlocking joints <NUM>. It is contemplated that the cell <NUM> may include fewer than four or more than four interlocking joints <NUM>, as desired. It is further contemplated that some interlocking joints <NUM> may be shared with an adjacent cell <NUM>. For example, some interlocking joint <NUM> may be eliminated to reduce the radial force exerted by the stent <NUM>. In some embodiments, each cell <NUM> may include one or more cross points <NUM> where the strands <NUM>, <NUM> cross but are not twisted to form a wrap as at the interlocking joints <NUM>.

It is contemplated that the size of the cells <NUM> may be controlled based on the number of helical strands <NUM>, <NUM>. For example, the larger the number of helical strands <NUM>, <NUM> the smaller the cells <NUM> will be. Said differently a stent having twelve helical strands <NUM>, <NUM> will have smaller cells <NUM> than the stent having six helical strands <NUM>, <NUM>. In some cases, both the longitudinal strands <NUM> and the helical strands <NUM>, <NUM> may be increased to reduce the size of the cells <NUM>. It is further contemplated that the longitudinal strands <NUM> may be uniformly spaced about the circumference of the stent <NUM>. This may result in cells <NUM> having similar sizes. In other embodiments, the longitudinal strands <NUM> may be positioned with unequal spacing or eccentric spacing about the circumference of the stent <NUM>. This may result in the stent <NUM> having cells <NUM> of differing sizes.

The stents, delivery systems, and the various components thereof, may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material. Some examples of suitable metals and metal alloys include stainless steel, such as 304V, <NUM>, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic Nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys, nickel-copper alloys, nickel-cobalt-chromium-molybdenum alloys, nickel-molybdenum alloys, other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys; platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material.

Some examples of suitable polymers for the stents or delivery systems may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-<NUM> (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like.

In at least some embodiments, portions or all of the stents or delivery systems may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are generally understood to be materials which are opaque to RF energy in the wavelength range spanning x-ray to gamma-ray (at thicknesses of <<NUM>"). These materials are capable of producing a relatively dark image on a fluoroscopy screen relative to the light image that non-radiopaque materials such as tissue produce. This relatively bright image aids the user of the stents or delivery systems in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the stents or delivery systems to achieve the same result.

Claim 1:
A stent (<NUM>), the stent (<NUM>) comprising: an elongated tubular member (<NUM>) comprising at least one knitted filament (<NUM>) having a plurality of twisted knit stitches with intermediate rung portions (<NUM>) extending between adjacent twisted knit stitches, the elongated tubular member (<NUM>) configured to move between a collapsed configuration and an expanded configuration; wherein in the collapsed configuration the plurality of twisted knit stitches have a first profile and in the expanded configuration the plurality of twisted knit stitches have a second profile different from the first profile; wherein a length of the intermediate rung portions (<NUM>) in the collapsed configuration is less than a length of the intermediate rung portions (<NUM>) in the expanded configuration.