DEVICES, SYSTEMS AND METHODS FOR ENGAGEABLE STENTS - Patent application

Abstract

The engageable stents disclosed herein may include an outer stent including an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration. The elongate body in the unconstrained configuration may include a retention member and a cylindrical saddle region adjacent the retention member, the cylindrical saddle region defining a lumen extending along a longitudinal axis of the outer stent. The retention member of the outer stent may include a double-walled flange. The engageable stents may include an inner stent including an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration. The elongate body in the unconstrained configuration may include a retention member and a cylindrical saddle region adjacent the retention member. The retention member of the inner stent may include a double-walled flange. The retention members of the outer stent and the inner stent are releasably engageable with one another.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of medical devices. In particular, the present disclosure relates to medical devices, such as one or more stents, for promoting or restricting the flow of fluids and matter along one or more body lumens. [Background technology]

[0002] Placement of a self-expanding stent within an anatomical region (e.g., a body lumen, airway, blood vessel, secretory duct, etc.) may allow for the passage or restriction of fluids from one region to another. For example, the stent may restrict or facilitate the flow of matter across a diseased sphincter.

[0003] However, available stents may have various disadvantages. For example, stents may be susceptible to dislodging or migrating from a desired location, e.g., when subjected to forces induced by patient movement, may not provide sufficient retention strength for a given use, or may provide too much retention strength for a given use. In addition, stents may need to be removed and / or replaced after significant ingrowth with the patient, risking trauma to the stent site during removal / replacement.

[0004] Thus, a variety of beneficial medical effects may be achieved by the devices, systems and methods of the present disclosure. Summary of the Invention

[0005] In one aspect, the system of stents may include an outer stent including an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration. The elongate body in the unconstrained configuration may include a retention member and a cylindrical saddle region adjacent to the retention member. The cylindrical saddle region may define a lumen extending along a longitudinal axis of the outer stent. The retention member of the outer stent may include a double-walled flange having an axially inner wall, an axially outer wall, and a radial wall extending therebetween. The inner stent of the system may include an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration. The elongate body in the unconstrained configuration may include a retention member and a cylindrical saddle region adjacent to the retention member. The cylindrical saddle region may define a lumen. The retention member of the inner stent may include a double-walled flange having an axially inner wall, an axially outer wall, and a radial wall extending therebetween. An axially inner wall of the retention member of the inner stent can be configured to releasably engage an axially outer wall of the retention member of the outer stent.

[0006] In the embodiments described herein or in other aspects of the present disclosure, the axially inner wall of the retaining member of the inner stent and the axially outer wall of the retaining member of the outer stent may each comprise a concave surface. The axially outer wall of the retaining member of the inner stent and the axially inner wall of the retaining member of the outer stent may each comprise a convex surface. The retaining member of the outer stent may be located at a distal portion of its elongate body. The retaining member of the inner stent may be located at a proximal portion of its elongate body. The longitudinal cross-sectional profile of the retaining member of the inner stent may substantially match the longitudinal cross-sectional profile of the retaining member of the outer stent. The axially outer wall of the retaining member of the inner stent may extend to a flexible sleeve that is connected to the lumen of the outer stent. The diameter of the cylindrical saddle region of the inner stent may be different from the diameter of the cylindrical saddle region of the outer stent. The radial wall of the outer stent may comprise a diameter larger than the diameter of the cylindrical saddle region of the outer stent. The elongate body of the outer stent may include a braid. The cylindrical saddle region of the outer stent may be twisted to have a reduced diameter portion. A flexible band may be disposed around the saddle region of the outer stent at the reduced diameter portion. The radial wall of the outer stent may have a diameter greater than the diameter of the radial wall of the inner stent. A coating, such as a cylindrical coating to encourage ingrowth, may extend at least partially along the length of the elongate body of the outer stent. Each of the retention members of the inner stent and the retention members of the outer stent may have a radiopaque marker. The inner stent may further include an element configured to reduce the profile of the inner stent and to detach the inner stent from the outer stent. A flexible sleeve may be coupled to the inner stent and may extend axially away from the retention member of the outer stent.

[0007] In one aspect, a stent may include an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration. The elongate body in the unconstrained configuration may include a proximal retention member and a cylindrical saddle region adjacent the proximal retention member. The cylindrical saddle region may define a lumen along a longitudinal axis of the stent. The proximal retention member may include a double-walled flange having an axially inner wall with a concave surface, an axially outer wall, and a radial wall extending therebetween. The proximal retention member may be configured to reversibly engage a retention member of another device.

[0008] In any of the embodiments described herein or in other aspects of the present disclosure, a distal retention member can be distal to a cylindrical saddle region. The distal retention member can include a double-walled flange having an axially outer wall with a concave surface, an axially inner wall, and a radial wall extending therebetween. The lumen of the cylindrical saddle region can decrease along the cylindrical saddle region from the larger diameters of the proximal and distal retention members to a smaller diameter.

[0009] In one embodiment, a method of delivering a stent system may include delivering an outer stent (with a retention member and a lumen extending therethrough) into a body lumen of a patient. An inner stent with a retention member may be delivered into the lumen of the outer stent such that the retention member of the inner stent is located within and releasably engaged with the retention member of the outer stent. The inner stent is removable from the outer stent. In-growth between the outer stent and the body lumen may be tolerated because the outer stent may remain in the patient longer than the inner stent, whereas the inner stent may be removed or replaced. The outer stent may be delivered into the body lumen (pyloric sphincter) and the inner stent may extend along the duodenum. The inner stent may include an element that can be pinched or twisted to restrain the inner stent from engagement with the outer stent. The inner stent may be delivered through the outer stent such that a portion of the inner stent extends distally beyond the distal end of the outer stent. [Brief description of the drawings]

[0010] Non-limiting examples of the present disclosure are described with reference to the accompanying figures, which are schematic and not intended to be drawn to scale. In the figures, each identical or nearly identical component shown is typically represented by a single numeral. For purposes of clarity, unless necessary to enable a person skilled in the art to understand the disclosure, not every component is labeled in every figure, and not every component in every embodiment of the present disclosure is shown. [Figure 1A] FIG. 1A shows a side view of an outer stent according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B illustrates an exemplary embodiment of a cross-sectional profile of a retention member, for example, for use with the outer stent of FIG. 1A. [Figure 1C]FIG. 1C illustrates an exemplary embodiment of a cross-sectional profile of a retention member of an inner stent engaging an exemplary embodiment of a cross-sectional profile of a retention member of an outer stent, for example in each case of the profile of FIG. 1B. [Figure 2A] FIG. 2A shows a cross-sectional profile of another retention member of a stent in accordance with an embodiment of the present disclosure. [Figure 2B] FIG. 2B shows a cross-sectional profile of another retention member of a stent according to an embodiment of the present disclosure. [Figure 2C] FIG. 2C shows a cross-sectional profile of another retention member of a stent according to an embodiment of the present disclosure. [Figure 2D] FIG. 2D shows a cross-sectional profile of another retention member of a stent according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 illustrates a system of a stent being delivered into a patient according to an embodiment of the present disclosure. [Figure 4A] FIG. 4A shows a stent that has been twisted to have a reduced diameter portion, according to an embodiment of the present disclosure. [Figure 4B] FIG. 4B illustrates a stent with a flexible band in a smaller diameter section according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present disclosure is not limited to the specific embodiments described. The terminology used in this specification is intended to describe only specific embodiments and is not intended to be limiting beyond the scope of the appended claims. Unless otherwise specified, technical terms used in this specification have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The detailed description should be read with reference to the drawings, which are not necessarily to scale and illustrate embodiments that are helpful in understanding and are not intended to limit the scope of the present invention.

[0012] As used herein, "proximal end" refers to the end of the instrument that is closest to a medical professional when inserting the instrument into a patient, and "distal end" refers to the end or object of the instrument that is furthest from a medical professional during implantation, placement, or delivery.

[0013] As used in this disclosure 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 ordinarily employed in its sense including "and / or," unless the content clearly dictates otherwise.

[0014] It should be noted that references herein to "one embodiment," "some embodiments," and "other embodiments" 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 a particular feature, structure, and / or characteristic. In addition, when a particular feature, structure, and / or characteristic is described with respect to one embodiment, it should be understood that such feature, structure, and / or characteristic may also be used with respect to other embodiments, whether or not expressly stated, unless otherwise clearly stated to the contrary.

[0015] All numerical values, whether explicitly stated or not, are assumed herein to be modified by the term "about". The term "about" generally refers to a range of numbers that one of ordinary skill in the art, in the context of the numerical values, would consider equivalent to the stated value (i.e., having a similar function or result). In many instances, the term "about" may include numbers rounded to the nearest significant figure. Other uses of the term "about" (i.e., in non-numerical contexts), unless otherwise specified, may be presumed to have the ordinary and accustomed definition(s) as understood from or consistent with the context of this specification. Recitation of numerical ranges by endpoints includes all numbers within the range, including the endpoints (e.g., recitation 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0016] Although embodiments of the present disclosure are described with specific reference to medical devices (e.g., stents) and systems for the restriction or drainage of the gallbladder, pseudocyst, gastrojejunostomy, and / or the like, it should be understood that such medical devices may be used in a variety of medical procedures (e.g., replacement of external bile drains, enteroenterostomy, gastroduodenostomy, gastroileostomy, etc.) to establish and / or maintain a temporary or permanent restricted or open flow path from, along, or between various body organs, lumens, secretory ducts, blood vessels, fistulas, cysts, and cavities (e.g., dermis, stomach, duodenum, jejunum, small intestine, gallbladder, kidney, pancreas, intrahepatic bile duct, pancreatic duct, urinary bladder, ureter, abscess, encapsulated pancreatic necrosis, extrahepatic bile duct, etc.), and may be inserted through a variety of access points and a variety of approaches (e.g., percutaneously, endoscopically, laparoscopically, or some combination thereof). While the medical devices disclosed herein are self-expanding, in other embodiments, the medical devices may be expandable by other methods including, for example, balloon catheters, etc. Additionally, such medical devices may facilitate access to an organ, vessel, or body lumen for other purposes, such as, but not limited to, restriction or drainage, for example, creating a pathway for diverting or bypassing fluids or solids from one point to another, removing obstructions, and / or administering therapy (including non-invasively or minimally invasively treating tissue within an organ and / or introducing pharmacological agents through an open flow path).

[0017] Referring to FIG. 1A, a side view of an embodiment of an outer stent 100 is illustrated in accordance with an embodiment of the present disclosure. The outer stent 100 includes an elongate body 110 that is expandable between a constrained configuration and an unconstrained configuration. In FIG. 1A, the elongate body 110 is illustrated in an unconstrained configuration. In the unconstrained configuration, the elongate body 110 is radially expandable to form a distal retention member 114 and a proximal retention member 124. The elongate body 110 includes a cylindrical saddle region 128 adjacent the retention members 114 and 124. The saddle region 128 defines a lumen extending along a longitudinal axis l of the outer stent 100. Each of the retention members 114 and 124 includes a double-wall flange having an axially inner wall 114a, an axially inner wall 124a, an axially outer wall 114b, an axially outer wall 124b, and a radial wall 114c, 124c extending therebetween. The distal retention member 114 and the proximal retention member 124 extend radially outward from the longitudinal axis 1 and from the outer circumference of the elongate body 110 in the unconstrained configuration, and each define a double-walled flange having an inner wall 114a, an outer wall 114b, an inner wall 124a, and an outer wall 124b. The inner wall 114a is axially inward along the distal retention member 114, the outer wall surface 114b is axially outward along the distal retention member 114, the inner wall 124a is axially inward along the proximal retention member 124, and the outer wall 124b is axially outward along the proximal retention member 124. The radial wall 114c of the distal retention member extends between and connects the inner wall 114a and the outer wall 114b. A radial wall 124c of the proximal retention member 124 extends between and connects the inner and outer walls 124a, 124b. Although the outer stent 100 in FIG. 1A is illustrated with a distal retention member 114 and a proximal retention member 124, the stents described herein may include only one of the distal retention member 114 and the proximal retention member 124.

[0018] 1B, an exemplary cross-sectional embodiment of a stent retention member is shown, for example, the distal retention member 114 of the outer stent 100 of FIG. 1A. The retention member 114 includes an outer wall 114b extending from a radial wall 114c. The outer wall 114b includes a first portion 116a and a second portion 116b. The first portion 116a is convex along the outer wall 114b, which extends to a concave second portion 116b. The radius of curvature of the first portion 116a is smaller than the radius of curvature of the second portion 116b. In various embodiments, the respective radii of curvature of the portions 116a and 116b of the outer wall 114b may be smaller, larger, or equal to each other, depending on the desired procedure. The inner wall 114a extends from the radial wall 114c to a first portion 118a that is convex before it further extends to a straight section in a second portion 118b that is at an angle of less than 90° from the longitudinal axis 1. The first portion 118a has a larger radius of curvature than the first portion 116a of the outer wall 114b. The second portion 118b extends to a third portion 118c of the inner wall 114a where the distal retention member 114 connects with the saddle region 128. The convex and / or concave portions may include similar or different angles to complete the curve, similar or different circumferential radii, similar or different lengths, similar or different other features, or combinations thereof.

[0019] In various embodiments, the stent or stents are configured to extend along, across, or between one or more lumens and may help to appose tissue layers (e.g., muscle layers), restrict flow, and / or temporarily or permanently facilitate flow. One or both of the first and second retention members at either end of the stent may be double-walled as described herein and may include one or more vertical or non-vertical surfaces that define the axially inner or axially outer wall of the retention member. These walls may be oriented relative to a cylindrical saddle region extending along the longitudinal axis between the two flanges. Such a non-vertical surface configuration may help inhibit migration of the stent relative to tissue(s) or another stent (e.g., an inner stent at least partially within an outer stent), for example, when compared to a corresponding retention member with a vertical surface. Additionally or alternatively, a retention member such as a double-walled flange with one or more non-vertical surfaces may be configured to be more resistant to being pulled out to remove the device from its intended location once deployed, e.g., having a higher pull-out force compared to a corresponding retention member with a vertical surface.For example, a double wall flange with a non-vertical surface may have a pull-out force of greater than about 4N, about 4.5N, about 5N, about 5.25N, about 5.5N, about 5.75N, or about 6N, such as greater than about 4.1N, about 4.2N, about 4.3N, about 4.4N, about 4.5N, about 4.6N, about 4.7N, about 4.8N, about 4.9N, about 5.0N, about 5.1N, about 5.2N, about 5.3N, about 5.4N, about 5.5N, about 5.6N, about 5.7N, about 5.75N, about 5.8N, about 5.9N, about 6.0N, about 6.1N, about 6.2N, about 6.3N, about 6.4N, about 6.5N, about 6.6N, about 6.7N, about 6.8N, about 6.9N, about 7.0N, about 7.1N, about 7.2N, about 7.3N, about 7.4N, about 7.5N, about 7.6N, about 7.7N, about 7.8N, about 7.9N, about 8.0N, about 8.1N, about 8.2N, about 8.3N, about 8.4N, about 8.5N, about 8.6N, about 8.7N, about 8.8N, about 8.9N, about 9.0N, about 9.0N, about 9.1N, about 9.2N, about 9.3N, about 9.4N, about 9.5N, about 9.6N, about 9.7N, about 9.8N, about 9.9N, about 9.0N, about 0.4N, about 6.5N, about 6.6N, about 6.7N, about 6.8N, about 6.9N, about 7.0N, about 7.1N, about 7.2N, about 7.3N, about 7.4N, about 7.5N, about 7.6N, about 7.7N, about 7.8N, about 7.9N, about 8.0N, about 8.1N, about 8.2N, about 8.3N, about 8.4N, about 8.5N, about 8.6N, about 8.7N, about 8.8N, about 8.9N, about 9.0N, about 9.5N, about 10N, about 11N, about 12N, about 13N, about 14N, about 15N, about 20N, about 25N, or thereabouts. In various embodiments, the one or more non-vertical surfaces may be configured to interact with at least one tissue wall of the first and second body lumens with less trauma (e.g., by configuring an inner wall such that the contact points with the tissue have a smaller surface area), as compared to a vertical surface or as compared to another surface having at least one tissue-engaging element (e.g., a prong, barb, hook, or other such feature).

[0020] Delivery of a stent into a patient's body may result in stent anchoring and / or placement along the patient's tissue. Removal or replacement of such a stent may undesirably damage the tissue. Therefore, it may be desirable to extend the duration of the stent in the patient's body and instead remove or replace a second stent configured to engage with the first stent. For example, an outer stent may be delivered into the patient to substantially engage and interface with the patient's tissue, and an inner stent may be delivered at least partially within the outer stent such that the inner stent engages with the outer stent. Such a configuration allows the inner stent to be removed from engagement with the outer stent or replaced with minimal damage to the tissue compared to removal or replacement of the outer stent.

[0021] Referring to FIG. 1C, the inner stent 102 is shown engaged to the outer stent 100 of FIGS. 1A and 1B. The inner stent 102 includes an elongate body 132 configured to be expandable between a constrained configuration and an unconstrained configuration. In FIG. 1C, the elongate body 132 of the inner stent 102 is in an unconstrained configuration, which includes a retention member 134 and a cylindrical saddle region 138 adjacent the retention member 134. The cylindrical saddle region 138 extends within the lumen of the saddle region 128 of the outer stent 100 and defines a lumen that is in fluid communication with the lumen. The retention member 134 of the inner stent 100 includes a double-walled flange having an axially inner wall 134a, an axially outer wall 134b, and a radial wall 134c extending therebetween. An axially inner wall 134 a of the retention member 134 of the inner stent 102 is releasably engaged with an axially outer wall 114 b of the distal retention member 114 of the outer stent 100 .

[0022] In various embodiments of a stent system including an inner stent engaged within an outer stent, one or more walls of the outer stent's retention member may assist in engaging the inner stent's retention member. For example, referring to FIG. 1C, the engagement interface between the concave axial outer wall 114b of the distal retention member 114 of the outer stent 100 and the concave axial inner wall 134a of the retention member 134 of the inner stent 102 increases the resistance and further increases the force threshold at which the inner stent 102 separates from the outer stent 100, as compared to a perpendicular wall (relative to the longitudinal axis 1). In various embodiments, one or more portions of the retention member 134 of the inner stent 102 may match (e.g., be complementary, align, engage, mimic, match, bond, or the like) one or more portions (e.g., at least a portion of the cross-sectional profile) of the distal retention member 114 of the outer stent 102. For example, the axial inner wall 134a matches the axial outer wall 114b. In addition, a portion of the retention member (e.g., portion 118c of the distal retention member 114) can disengage from the distal retention member 114 to resist radially inward movement of the retention member (e.g., retention member 134), e.g., by engaging (e.g., by securing or bonding) with at least a portion (e.g., portion 139) of the retention member 134. In addition, an axial wall of the retention member (e.g., axially inner wall 114a of the distal retention member 114) may, e.g., allow and provide room for flexibility for the retention member (e.g., retention member 134) to engage with the distal retention member 114. Once engaged, the retention members 114 and 134 can fit together such that a surface of the retention member 114 and a surface of the retention member 134 are in full or substantially full contact with each other, e.g., resisting movement and / or sliding relative to each other.

[0023] In various embodiments, the inner stent may include one or more retention members. In embodiments of an inner stent including a single retention member, the elongate body of the stent may extend away from the single retention member to form a lumen (e.g., along a body lumen such as the duodenum) within the flexible sleeve and / or saddle region. The sleeve may be everted after or during delivery of the inner stent into the outer stent, e.g., by delivering the inner stent to engage a distal retention member of the outer stent and everting the sleeve along the outer stent such that the sleeve extends proximally from the outer stent (e.g., in the colon or small intestine).

[0024] In various embodiments, the diameter of the retention member may be in the range of about 5 mm to about 40 mm. Other exemplary retention member diameters may be about 15 mm to about 40 mm, about 15 mm to about 35 mm, or within such ranges. In various embodiments, the diameter of the retention member may be set to have a particular offset from the diameter of the cylindrical saddle region in the unconstrained configuration. For example, the stent may be configured to include a difference between the diameter of the cylindrical saddle region and the diameter of the first retention member and / or the second retention member in the unconstrained configuration of about 3 mm to about 20 mm. In other examples, the first retention member and / or the second retention member may be configured to have a diameter in the unconstrained configuration that is about 1 to 5 times larger than the diameter of the cylindrical saddle region. For example, in a device having a cylindrical saddle region with a diameter of about 10 mm in the unconstrained configuration, the first retention member and / or the second retention member may have a diameter of about 13 mm to about 30 mm, about 15 mm to about 25 mm, or about 16 mm to about 20 mm. In another example, a stent having a cylindrical saddle region with a diameter of about 20 mm in an unconstrained configuration may have one or more retention members with a diameter of about 23 mm to about 40 mm. It will be understood that some embodiments may include a significant or slight offset between the diameter of the cylindrical saddle region and the larger diameter of the first retention member and / or the second retention member. In various embodiments, a retention member may have a substantially similar or different axial width to another retention member of a similar or different stent. The axial width of a retention member is measured as the distance along the longitudinal axis between the axially inner and axially outer walls of the respective retention member, including the radial wall. In various embodiments, the width of a retention member in an unconstrained configuration may be about 0.5 mm to about 10.0 mm. Other embodiments may include one or more retention members with a smaller and / or larger width, for example, about 0.5 mm to about 6 mm, about 2 mm to about 6 mm, or about 3 mm to about 7 mm. In some embodiments, a retention member may have a constant width. In other embodiments, the width of the retention member may vary along a perpendicular plane (i.e., a plane perpendicular to the longitudinal axis of the elongate body of the stent).Various embodiments may include, for example, a total stent length in the unconstrained configuration ranging from about 5 mm to about 60 mm.For example, an exemplary deployed stent may have a length of about 10 mm to about 50 mm, about 10 mm to about 35 mm, or so. If it is desired to require a large pull-out force to remove the stent, the diameter ratio between the retention member and the adjacent saddle region or elongate body may be large, and if it is desired to require a small pull-out force to remove the stent, the diameter ratio between the retention member and the adjacent saddle region or elongate body may be small.

[0025] In various embodiments, the length of the cylindrical saddle region may be measured as (i) the length along the elongate body between the beginning of the axially inner wall(s) of one or more retention members, (ii) the length along the body where the retention members are the smallest distance between any point along the inner wall of the retention members when the stent is unconstrained and not deployed along tissue, (iii) the length along the body where the retention members are the smallest distance between any point along the inner wall of the retention members when the stent is unconstrained and deployed along tissue, or (iv) the length along the body from a point along the inner wall of a single retention member of the stent to the opposite end of the elongate body. In various embodiments, the cylindrical saddle region, including under conditions (i)-(iv) above, may have a length of about 5 mm to about 150 mm in the unconstrained configuration, a length of about 5 mm to about 35 mm in the unconstrained configuration, or a length therebetween. Exemplary lengths of the cylindrical saddle region of a stent for gastrointestinal function in the unconstrained configuration may include lengths of about 10 mm to about 30 mm, about 15 mm to about 20 mm, about 10 mm to about 20 mm, about 10 mm to about 15 mm, about 5 mm to about 10 mm, or so. In many embodiments, the diameter of the cylindrical saddle region in the unconstrained configuration may be larger than the diameter of the elongate body in the constrained configuration. For example, the diameter of the cylindrical saddle region in the unconstrained configuration may be about 3 mm to about 40 mm. In some embodiments, the diameter of the cylindrical saddle region in the unconstrained configuration may be about 5 mm to about 25 mm, about 5 mm to about 20 mm, about 5 mm to about 15 mm, about 10 mm to about 20 mm, or so. In various embodiments, the diameter of the cylindrical saddle region may be about 3 to 5 times, about 3 to 10 times, or so, larger than the corresponding diameter of its elongate body in the constrained configuration.

[0026] In various embodiments, the elongate body of the stent may be partially or fully covered, uncovered, coated, or a combination thereof. The elongate body may include a constrained configuration (e.g., an unexpanded or delivery configuration), an unconstrained configuration (e.g., a reduced length configuration, an expanded configuration, or a deployed configuration), and a partially constrained / unconstrained transition state between the constrained and unconstrained configurations.

[0027] The non-vertical surfaces of the retention members, comprising the axially inner and axially outer walls of the double-walled flange, may include one or more curved, straight, angled, concave, convex portions, or any combination thereof. Each portion may include a substantially equal or different length, angle, radius of curvature, orientation, angle, or other feature relative to another portion. The surfaces of the first retention member and the second retention member may be similar or different. For example, each end of the medical device may be designed to improve the strength (e.g., resistance to pull-out or retention strength, or resistance to radial or radial strength) of the stent or a portion of the stent, thereby providing a desired amount of linear apposition force when positioned across a tissue plane and / or when engaging another stent. The shape of the retention members may include one or more rolls and / or structural folds, for example, to create a double-walled flange structure. In various embodiments, the retention member may include multiple inflection points, which may be points of bending where a change in the direction of curvature occurs.

[0028] 2A-2D, various cross-sectional profiles of retention members of a stent are illustrated in accordance with embodiments of the present disclosure. The configuration of retention members as described with respect to FIGS. 2A-2E may be substituted or applied to any of the embodiments described herein. For example, distal retention member 114 as described with respect to FIG. 1A, proximal retention member 124 as described with respect to FIG. 1A, retention members as described with respect to FIG. 1C, and / or other retention members described herein may have a configuration as described with respect to FIGS. 2A-2E. Thus, an embodiment may include multiple retention members with similar configurations or different configurations.

[0029] 2A, the elongated body 210 includes a retaining member 202. The retaining member 202 includes a first wall 204, a second wall 206 axially offset from the first wall 204 along a longitudinal axis 1, and a radial wall 208 extending therebetween. A cylindrical saddle region 228 is adjacent to and extends from the first wall 204. The second wall 206 includes three portions: portion 206a, portion 206b, and portion 206c. The cylindrical saddle region 228 may extend to a concave surface of portion 206a, which extends to portion 206b. The portion 206b includes a substantially straight section that extends at an angle of less than 90° from the longitudinal axis 1. The portion 206c includes a convex curvature that extends between portion 206b and the radial wall 208. The radial wall 208 includes a portion that is substantially parallel to the longitudinal axis 1. The radial wall 208 extends to the first wall 204, which includes a portion 204a and a portion 204b. The portion 204a includes a convex surface having a variable radius along its length. The convex and / or concave surfaces may include similar or different angles to complete the curvature, similar or different circumferential radii, similar or different lengths, similar or different other features, or combinations thereof. The portion 204b is concave and connects to the remainder of the elongated body 210.

[0030] Referring to FIG. 2B, another exemplary embodiment is illustrated in which the retaining member 202 may include similar portions 206a, 206b, and 206c as described with respect to FIG. 2A. However, the portion 204a as illustrated in FIG. 2B may include a larger radius of curvature than the portion 204a as illustrated in FIG. 2A. In FIG. 2B, the portion 204b may include a substantially straight section extending rearward from the radial wall 208 and the portion 204a toward the cylindrical saddle region 228. The portion 204b may extend to the portion 204c, which is illustrated in FIG. 2B as including a concave portion. The portion 204c extends to the remainder of the elongated body 210. The angle of the retaining member 202 defined by the portions 204b and 206b is less than 90° with respect to the longitudinal axis 1.

[0031] 2C, another exemplary embodiment is illustrated in which the retaining member 202 includes a portion 206a having a concave curvature that extends to a substantially straight section of portion 206b. The portion 206b extends to a convex curvature of portion 206c, which then extends to a radial wall 208. The radial wall 208 extends to a portion 204a having a convex curvature. The portion 204a extends to a substantially straight section of portion 204b, which then extends to a portion 204c having a concave curvature. The substantially straight sections of portion 204b and portion 206b are formed at an angle of less than 90° with respect to the longitudinal axis 1. The portion 204c extends to the remainder of the elongated body 210. However, one or more of portions 206a, 206c, 204a, and / or 204c may have a smaller radius of curvature than that shown (e.g., as shown for concavely curved portion 204c in FIG. 2A compared to concavely curved portion 204c in FIG. 2C). However, other sections may additionally or alternatively be substituted for one or more sections of the retention members of other embodiments described herein. In various embodiments, at least a portion of the concave or convex curvature may have a radius of curvature small enough to include creases or other folds.

[0032] Referring to FIG. 2D, another exemplary embodiment is illustrated in which the retention member 202 includes similar portions 206a, 206b, and 206c as described with respect to at least one of FIGS. 2A-2C. The portion 206a as illustrated in FIG. 2D includes a radius of curvature greater than the radius of curvature of the portion 206a of FIG. 2A. For example, the portion 206a as illustrated in FIG. 2D may include a radius of curvature between about 1 mm and about 3 mm. In various embodiments, the portion 206a and / or the portion 206c may include a radius of curvature between about 1.5 mm and about 2.1 mm. In FIG. 2D, the portion 206a may include a varying radius of curvature along its length. As illustrated in FIG. 2D, the portion 206a extends radially away from the saddle region 228 toward the longitudinal axis 1 such that a section of the portion 206a is closer to the longitudinal axis 1 than the cylindrical saddle region 228. Portion 206d extends between saddle region 228 and portion 206a. In various embodiments, portion 206a or other portions 206b, 206c, 206d may include an uneven and / or otherwise wavy curvature. Portion 204b of first wall 204 includes a straight portion that is substantially perpendicular to longitudinal axis l, as shown in FIG. 2D. Portion 204c includes a concave surface that extends to the remainder of elongate body 210.

[0033] While various profiles of the retention members are described with respect to Figures 2A-2D, it should be understood that various embodiments may include one or more similarities and / or differences from the illustrated examples. For example, the first wall 204 or the second wall 206 may be comprised of additional or fewer portions, any of which may include a concave section, a convex section, a substantially straight section, or any combination thereof. A portion may extend toward the first or second end of its elongate body perpendicular to the longitudinal axis, parallel to the longitudinal axis, at another angle to the longitudinal axis, or any combination thereof. Additionally, any dimensions and / or orientations of portions described with respect to Figures 2A-2D may be applied alternatively or in combination with other portions described therewith, or may otherwise be applied with the profile of portions and / or retention members within the scope of this disclosure.

[0034] In various embodiments, a smaller radius of curvature for such portions may contribute to a higher retention strength and / or resistance of the corresponding retention member. For example, the retention member configuration illustrated in FIG. 1B may be more resistant to deformation than the respective configuration in FIG. 2A. Thus, embodiments may be configured to comply with various retention member strength and / or resistance requirements as necessitated by at least one particular procedure, tissue, stent engagement, stent function, or other considerations.

[0035] In various embodiments, the stent may be formed from one or more filaments and / or surfaces. In various embodiments, one or more metal wires, one or more wire braids, polymer filaments, sheets, or combinations thereof may form the stent. The stent may include one or more structural elements (e.g., struts, hoops, meshes, tessellating cells, or other units, etc.). In many embodiments, the stent may include mesh-like, woven, and / or knitted surfaces. In various embodiments, the stent may be formed from a shape memory material (e.g., Nitinol, etc.). Features (e.g., retention members, saddle regions, etc.) of portions or the entire stent may include radiopaque markers to allow a user to identify the location of one or more features across the stent or stents. For example, any portion of the retention member of the inner stent may be radiopaque along with any portion of the retention member of the outer stent, allowing a user to identify their relative locations during delivery and deployment to ensure a desired engagement / configuration between the two.

[0036] Various stent embodiments described herein may include a full or partial coating, covering, or other film that covers the interior of the device, covers the exterior of the device, extends between structural elements, or any combination thereof. For example, the coating, covering, or other film may include silicone, polymer, or combinations thereof. For example, the coating may include polyurethane, polytetrafluoroethylene, expanded polytetrafluoroethylene, polyvinylidene fluoride, aromatic polycarbonate-based thermoplastic polyurethane, and / or other such materials. The coating may include an ingrowth-promoting material for interfacing with tissue. The coating may be applied by dip coating, roll coating, painting, spraying, other known processing methods, or combinations thereof. The coating, covering, or other film may inhibit tissue growth and / or minimize fluid leakage from the interior and / or exterior of the stent. The first retention member, the second retention member, the saddle region extending between the first retention member and the second retention member, or a combination thereof, may comprise a solid coating, a porous coating, or other coating configuration. In various embodiments, the circumferential coating or covering may be applied to cover the entire length of the stent or a partial length of the stent. For example, a partial coating may cover the entire length of the saddle region but not the flanges, or vice versa.

[0037] Various embodiments described herein may include one or more additional features designed to engage at least one tissue layer. For example, embodiments may include textured surfaces, prongs, or other tissue-engaging elements along one or more retention members.

[0038] Various embodiments herein may include retention members and alternative configurations at opposing ends or portions of the stent. For example, various embodiments may include flanges with walls perpendicular to the longitudinal axis, flared retention members, bulbous retention members, ramped retention members, curled retention members, folded retention members, or other configurations. Some embodiments may include one or more configurations for managing the flow of objects therethrough. For example, various embodiments may include valves, barrier members, funnels, tubes, reducers, or other configurations useful for managing flow therethrough.

[0039] In various embodiments of the medical device, at least a portion of one or more walls of the retention member may include at least one curved section, a straight section, a section angled relative to the longitudinal axis, a section perpendicular to the longitudinal axis, a section horizontal to the longitudinal axis, a radius of curvature, or any combination thereof. Although the cross-sectional profiles of the retention members are illustrated and described herein in particular orientations, it is understood that any retention member may be inverted, flipped, or mirrored in orientation (e.g., across the "x" (horizontal) or "y" (vertical) axes of the drawings of this disclosure) depending on the procedure (e.g., endoscopic procedure, colonoscopic procedure, desired engagement between the retention member(s) and tissue or other retention member(s), atraumatic concerns during delivery, placement, or removal, or the like).

[0040] 3, a system of stents is shown being delivered into a patient's body in accordance with an embodiment of the present disclosure. The outer stent 300 may be positioned along the patient's tissue 350 and extend across an opening in a tissue wall or apposing tissue wall (e.g., a sphincter 352 such as the pyloric sphincter). The outer stent 300 may be delivered in a constrained configuration along a guidewire 360 ​​while being constrained by a retractable sheath 362, which may include a radiopaque marker 364 at its distal end. The sheath 362 may be retracted to position the outer stent 300 along the tissue 350 in an unconstrained configuration such that the distal retention member 314 and the proximal retention member 324 can engage the tissue 350. Once the outer stent 300 is positioned as shown in FIG. 3, a guidewire 360 ​​and sheath 362 may be passed through the outer stent 300 to deliver the inner stent 302 in a constrained configuration, over the guidewire 360 ​​and constrained by the sheath 362 (although the inner stent 302 may be delivered and positioned using a separate guidewire and / or sheath). The distal end of the guidewire 360 ​​and the sheath 362 are extended distally beyond the outer stent 300 to deploy the inner stent 302. The inner stent 302 is partially unconstrained by retracting the sheath 362 proximally relative to the guidewire 360. A distal portion 302d of the inner stent 302 is unconstrained, while a proximal portion of the stent 302 is constrained by and within the sheath 362. The proximal portion of the stent, including the retention member, may be free to engage the distal retention member 314 of the outer stent 300 (e.g., as shown in FIG. 1C , the retention member 134 of the inner stent 102 engages the distal retention member 114 of the outer stent 100). Although FIG. 3 is shown / described as positioning the inner stent 302 to engage only the distal retention member 314 of the outer stent 300, in various embodiments the inner stent 302 may include two retention members, one each for engaging the distal retention member 314 and the proximal retention member 324 of the outer stent.Although FIG. 3 illustrates / describes the inner stent 302 as being partially positioned distally beyond the outer stent 300, the inner stent 302 may be positioned at least partially proximal to the outer stent 300 (e.g., in the large or small intestine), or the inner stent 302 may be positioned entirely within the outer stent 300 (e.g., so as to engage both the distal retention member 314 and the proximal retention member 324 of the outer stent 300).

[0041] 4A, in accordance with an embodiment of the present disclosure, a stent 400 is shown including a twist 430 along its saddle region 428. The saddle region 428 reduces in diameter from each of the distal and proximal retention members 414, 424 along the longitudinal axis 1 toward the twist 430. The stent 400 is shown in an unconstrained configuration. The twist 430 may be expandable, for example, such that another device (e.g., a guidewire, a catheter, and / or another stent) or the like may pass through the twist 430 of the unconstrained stent 400 at the same time that the saddle region 428 partially untwists or otherwise expands to accommodate the diameter of the additional device(s). The twist 430 may return substantially to the illustrated configuration upon removal of the device(s) from within the saddle region 428. Additionally or alternatively, the twist 430 may act as a reducer / restrictor for flow along the longitudinal axis 1 and may include a coating and / or covering. It should be understood that the stent 400 may be an outer stent or an inner stent as described herein. For example, the stent 400 may be placed along the tissue and an inner stent may be placed within the stent 400, or the stent 400 may be placed within an outer stent. The reduced diameter portions of the saddle region 428 may be larger or smaller depending on the flow reduction, obstruction, body lumen patency, size of the device passing therethrough, or the fit of the saddle region 428 around the device.

[0042] 4B, the saddle region 428 of the stent 400 may similarly be reduced in diameter with the use of bands 432 rather than twists 430 of FIG. 4A. As illustrated in FIG. 4B, the saddle region 428 reduces in diameter along the longitudinal axis 1 from each of the distal and proximal retention members 414, 424 to the bands 432. Although the stent 400 is illustrated in an unconstrained configuration, the bands 432 constrain a portion of the saddle region 428. The bands 432 may be flexible such that another instrument may penetrate the saddle region 428 and expand the saddle region 428 and bands 432 around the instrument. The bands 432 and saddle region 428 may substantially return to the configuration illustrated in FIG. 4B upon removal of the instrument from within the saddle region 428. Additionally or alternatively, the bands 432 may function as a reducer / restrictor for flow along the longitudinal axis 1 and may include a coating and / or covering. It should be understood that the stent 400 can be an outer stent or an inner stent as described herein. For example, the stent 400 may be placed along the tissue and an inner stent may be placed within the stent 400, or the stent 400 may be placed within the outer stent. The reduced diameter portions of the saddle region 428 may be larger or smaller depending on the flow reduction, obstruction, body lumen patency, size of the device passing therethrough, or the fit of the saddle region 428 around the device.

[0043] An embodiment of a method of delivering a stent system disclosed herein may include delivering an outer stent (comprising a retention member and a lumen extending therethrough) into a body lumen of a patient. An inner stent including a retention member may be delivered into the lumen of the outer stent such that the retention member of the inner stent is disposed within and releasably engages the retention member of the outer stent. The inner stent is removable from the outer stent. In-growth between the outer stent and the body lumen may be tolerated because the outer stent may remain in the patient longer than the inner stent, whereas the inner stent may be removed or replaced. The outer stent may be delivered into the body lumen (pyloric smooth muscle) and the inner stent may extend along the duodenum. The inner stent may include elements (e.g., bands, sutures, strings, wires, or the like) that can be pinched or twisted to constrain the inner stent (e.g., to separate the inner stent from the retention member(s) of the outer stent prior to removal). The inner stent may be removed from the outer stent in a variety of ways, such as by pinching the inner stent or elements connected to the inner stent (e.g., sutures, loops, wires, etc.) with an instrument (e.g., forceps, graspers, clamps, etc.) and pulling, pushing, and / or twisting the instrument to separate the inner stent from the outer stent. The inner stent may be delivered through the outer stent.

[0044] All of the apparatus and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the apparatus and methods of the present disclosure have been described in terms of preferred embodiments, it will be apparent to those skilled in the art that modifications may be applied to the apparatus and / or methods described herein and to the steps or sequence of method steps without departing from the concept, spirit and scope of the present disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the present disclosure as defined by the appended claims.

Claims

1. 1. A stent system comprising: The outer stent is an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration, the elongate body in the unconstrained configuration including a retention member and a cylindrical saddle region adjacent the retention member, the cylindrical saddle region defining a lumen extending along a longitudinal axis of the outer stent; the retention member of the outer stent includes a double-walled flange having an axially inner wall, an axially outer wall, and a radial wall extending therebetween. the outer stent; The inner stent an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration, the elongate body in the unconstrained configuration including a retention member and a cylindrical saddle region adjacent the retention member, the cylindrical saddle region defining a lumen; the retention member of the inner stent includes a double-walled flange having an axially inner wall, an axially outer wall, and a radial wall extending therebetween; the axially inner wall of the retention member of the inner stent is configured to releasably engage the axially outer wall of the retention member of the outer stent. the inner stent; Including, The system.

2. 2. The system of any preceding claim, wherein the axially inner wall of the retention member of the inner stent and the axially outer wall of the retention member of the outer stent each comprise a concave surface.

3. 2. The system of any preceding claim, wherein the axially outer wall of the retention member of the inner stent member and the axially inner wall of the retention member of the outer stent each comprise a convex surface.

4. 2. The system of any preceding claim, wherein the retention member of the outer stent is located at a distal portion of the elongate body and the retention member of the inner stent is located at a proximal portion of the elongate body.

5. 2. A system according to any preceding claim, wherein a longitudinal cross-sectional profile of the retention member of the inner stent substantially matches a longitudinal cross-sectional profile of the retention member of the outer stent.

6. 10. The system of claim 1, wherein the axially outer wall of the retention member of the inner stent member extends to a flexible sleeve that abuts the lumen of the outer stent.

7. 2. The system of any preceding claim, wherein a diameter of the cylindrical saddle region of the inner stent is different from a diameter of the cylindrical saddle region of the outer stent.

8. 2. The system of any preceding claim, wherein the radial wall of the outer stent has a diameter greater than a diameter of the cylindrical saddle region of the outer stent.

9. 2. The system of any preceding claim, wherein the elongate body of the outer stent comprises a braid, and the cylindrical saddle region of the outer stent is twisted to have a reduced diameter portion.

10. 2. The system of any preceding claim, wherein the radial wall of the outer stent includes a diameter greater than a diameter of the radial wall of the inner stent.

11. 2. The system of any preceding claim, further comprising a coating extending at least partially along the elongate body of the outer stent.

12. 2. The system of any preceding claim, further comprising a radiopaque marker on each of the retention members of the inner stent and the outer stent.

13. 2. The system of any preceding claim, wherein the inner stent further comprises elements configured for reducing a profile of the inner stent and for detaching the inner stent from the outer stent.

14. 2. The system of any preceding claim, further comprising a flexible sleeve coupled to the inner stent and extending axially away from the retention member of the outer stent.

15. 1. A stent comprising: an elongate body configured to be expandable between a constrained configuration and an unconstrained configuration, the elongate body including a proximal retention member and a cylindrical saddle region adjacent the proximal retention member in the unconstrained configuration, the cylindrical saddle region defining a lumen along a longitudinal axis of the stent; the proximal retention member includes a double-walled flange having an axially inner wall including a concave surface, an axially outer wall, and a radial wall extending therebetween; the proximal retention member is configured for reversible engagement with a retention member of another device; Stent.

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