Stent with selective membrane coating

Abstract

Medical devices and methods for using the medical devices are disclosed. An exemplary medical device includes a support structure including an inner surface, an outer surface, a proximal end region, a distal end region, a lumen extending from the proximal end region to the distal end region, and a retention member extending radially away from the outer surface. The retention member has a distal-facing surface and a proximal-facing surface. A membrane is disposed within the lumen of the tubular support structure and secured to the inner surface of the tubular support structure at first and second circumferential attachment regions. Furthermore, the membrane is unattached to the inner surface of the tubular support structure between the first and second circumferential attachment regions, defining a tissue ingrowth region between the inner surface of the tubular support structure and the outward-facing surface of the membrane.

Description

[Technical Field]

[0001] The present disclosure relates to medical devices, methods for manufacturing medical devices, and uses thereof. More particularly, the present disclosure relates to stents with selective membrane coatings for implantation within a body lumen, and related methods. [Background technology]

[0002] Implantable medical devices (e.g., expandable stents) can be designed to treat a variety of medical conditions within the body. For example, some expandable stents can be designed to expand radially and support a body lumen and / or provide a fluid pathway for digested material, blood, or other bodily fluids to flow following a medical procedure. Some medical devices can include radially expandable stents or self-expanding stents that can be implanted percutaneously by various medical device delivery systems. These stents can be implanted in various body lumens, such as the coronary or peripheral arteries, esophagus, gastrointestinal tract (including the intestines, stomach, and colon), bronchi, urinary tract, biliary tract, vasculature, etc.

[0003] In some instances, it may be desirable to design a stent to include sufficient flexibility while maintaining sufficient radial force to open a body lumen at the treatment site. However, in some stents, the compressibility and flexibility characteristics that aid in stent delivery can also cause the stent to migrate from its initial placement location. For example, stents designed for placement in the gastrointestinal and / or biliary tract may migrate due to peristalsis (i.e., the involuntary contraction and relaxation of the muscles of the stomach, intestine, and colon). Furthermore, the generally moist and inherently smooth environment of the stomach, intestine, colon, etc., can increase the tendency of a stent to migrate when placed therein. Furthermore, the relative movement of unconnected structures (e.g., the relative movement of the hepatic duct and stomach) can increase the tendency of a stent to migrate when placed therein.

[0004] Various medical procedures involve the temporary or permanent joining of unconnected anatomical structures. Some examples include hepatogastrostomy (HGS), which involves joining the hepatic duct to the stomach to drain the hepatic duct; EUS-guided gallbladder drainage (EUS-GBD), which is used to treat acute cholecystitis and symptomatic cholelithiasis in patients with poor surgical indications; gastrojejunal (GJ) bypass or gastrojejunostomy, which creates an anastomosis between the small intestinal wall and the stomach wall; and stomas, which create artificial openings in the large intestine or other regions of the digestive tract. In these medical procedures, peristalsis and macroscopic organ movement in one or both of the connected anatomical structures can make it difficult to use stents to join the structures due to stent migration. Therefore, procedures may require a stent that allows leak-free drainage from one anatomical structure (e.g., hepatic duct) to another (e.g., Ebami, stomach) while allowing tissue ingrowth into the stent to prevent stent migration.

[0005] Therefore, it may be desirable to design a stent with both drainage and anti-migration features to reduce the tendency of the stent to migrate. Disclosed herein are examples of medical devices that include both drainage and anti-migration features, and methods of using them. Summary of the Invention

[0006] The present disclosure provides alternatives for medical device design, materials, manufacturing methods, and uses. An exemplary expandable medical device includes a tubular support structure (tubular scaffold) having an inner surface, an outer surface, a proximal end region, a distal end region, a lumen extending from the proximal end region to the distal end region, and a retention member extending radially away from the outer surface, the retention member having a distal-facing surface and a proximal-facing surface. The medical device also includes a membrane disposed within the lumen of the tubular support structure. The membrane is secured to the inner surface of the tubular support structure at a first circumferential attachment region, and the membrane is secured to the inner surface of the tubular support structure at a second circumferential attachment region. Furthermore, the membrane is unattached to the inner surface of the tubular support structure between the first and second circumferential attachment regions, defining a tissue ingrowth region between the inner surface of the tubular support structure and the outward-facing surface of the membrane.

[0007] Alternatively or additionally to the above embodiments, the membrane is configured to maintain a passageway. Alternatively or additionally to the above embodiments, the tissue ingrowth region extends circumferentially around the inner surface of the tubular support structure.

[0008] Alternatively or additionally to the above embodiments, the membrane is formed from an elastic material. Alternatively or additionally to the above embodiments, the membrane is designed to allow tissue ingrowth between the inner surface of the tubular support structure and the outward facing surface of the membrane.

[0009] Alternatively or additionally to the above embodiments, a first circumferential attachment region is secured to the inner surface of the tubular support structure along the distal end region, and a second circumferential attachment region is secured to the inner surface of the tubular support structure at a location distal to the retention member.

[0010] Alternatively or additionally to the above embodiments, the tubular support structure includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and the membrane spans the plurality of gaps in a portion of the tubular support structure that defines the retention member.

[0011] Alternatively or additionally to the above embodiments, the tubular support structure includes a plurality of gaps extending from an outer surface of the tubular support structure to an inner surface of the tubular support structure, and the membrane encloses the plurality of gaps in a portion of the tubular support structure that defines the retention member.

[0012] Alternatively or additionally to the above embodiments, a first circumferential attachment region is secured to the inner surface of the tubular support structure along the distal end region, and a second circumferential attachment region is secured to the inner surface of the tubular support structure at a location proximal to the retention member.

[0013] Alternatively or additionally to the above embodiments, the tubular support structure includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, allowing tissue to grow through the plurality of gaps in a portion of the tubular support structure between the first circumferential attachment region and the second circumferential attachment region.

[0014] Alternatively or additionally to the above embodiments, the distal end region of the tubular support structure further includes a flared portion. Alternatively or additionally to the above embodiments, the first circumferential attachment region is secured to the inner surface of the tubular support structure at a location proximal to the flared portion, and the second circumferential attachment region is secured to the inner surface of the tubular support structure at a location distal to the retention member.

[0015] Alternatively or additionally to the above embodiments, the membrane is in direct contact with the inner surface of a portion of the tubular support structure that defines the retention member. Alternatively or additionally to the above embodiments, the flared portion includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and the flared portion does not have a membrane to allow tissue to grow along the flared portion and through the plurality of gaps in the tubular support structure.

[0016] Alternatively or additionally to the above embodiments, the retaining member has a diameter, the flared portion has a diameter, and the diameter of the retaining member is greater than the diameter of the flared portion. Alternatively or additionally to the above embodiments, the distally facing surface of the retention member is substantially parallel to the proximally facing surface of the retention member.

[0017] Alternatively or additionally to the above embodiments, the membrane is further secured to the inner surface of the tubular support structure at a plurality of spaced apart, discrete attachment points disposed between the first circumferential attachment region and the second circumferential attachment region.

[0018] Alternatively or additionally to the above embodiments, the regions of the membrane between the plurality of spaced apart discrete attachment points are radially spaced from the inner surface of the tubular support structure, forming a plurality of tissue ingrowth regions disposed between the first and second circumferential attachment regions.

[0019] Another expandable medical device includes a tubular support structure including an inner surface, an outer surface, a proximal end region, a distal end region including a flared portion, a lumen extending from the proximal end region to the distal end region, and a retention member extending radially away from the outer surface, the retention member having a distal-facing surface disposed substantially parallel to the proximal-facing surface. The medical device also includes a membrane disposed within the lumen of the tubular support structure, the membrane secured to the inner surface of the tubular support structure at a first circumferential attachment region and the membrane secured to the inner surface of the tubular support structure at a second circumferential attachment region, the membrane configured to maintain a passageway.

[0020] Another expandable medical device includes a tubular support structure including an inner surface, an outer surface, a proximal end region, a distal end region including a flared portion, a lumen extending from the proximal end region to the distal end region, and a retention member extending radially away from the outer surface, the retention member having a distal-facing surface disposed substantially parallel to the proximal-facing surface. The medical device also includes a membrane disposed within the lumen of the tubular support structure, the membrane secured to the inner surface of the tubular support structure at a first circumferential attachment region and the membrane secured to the inner surface of the tubular support structure at a second circumferential attachment region. Furthermore, the flared portion includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, the flared portion being membrane-free to allow tissue growth along the flared portion and through the plurality of gaps in the tubular support structure.

[0021] The foregoing summary of some embodiments is not intended to describe each embodiment or every implementation of the present disclosure. The figures and detailed description that follow more particularly exemplify these embodiments. [Brief explanation of the drawings]

[0022] The present disclosure may be more fully understood in view of the following detailed description of various embodiments in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 1 illustrates regions of the digestive tract. [Figure 2] 1A-1C illustrate an exemplary stent including a flared portion. [Figure 3] 3 is a cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 4] 3 is another cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 5] 3 is another cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 6] 3 is another cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 7] 3 is another cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 8]3 is another cross-sectional view of the stent of FIG. 2 including an inner membrane. [Figure 9] 9 is a cross-sectional view of the exemplary stent taken along line 9-9 of FIG. 8. [Figure 10] 1A-1C illustrate an exemplary stent positioned in a portion of the digestive tract. [Figure 11] FIG. 10 shows another exemplary stent in a relaxed configuration. [Figure 12] FIG. 12 shows the exemplary stent of FIG. 11 in an expanded configuration. [Figure 13] FIG. 12 is a cross-sectional view of the stent shown in FIG. [Figure 14] FIG. 13 is a cross-sectional view of the stent shown in FIG. [Figure 15] FIG. 10 shows another exemplary stent in a relaxed configuration. [Figure 16] 16 is a cross-sectional view of the exemplary stent of FIG. 15 in an expanded configuration. DETAILED DESCRIPTION OF THE INVENTION

[0023] While the present disclosure is susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure.

[0024] For the following defined terms, these definitions shall be applied unless a different definition is given in the claims or elsewhere in this specification. All numerical values ​​herein are assumed to be modified by the term "about," whether explicitly stated or not. The term "about" generally refers to a range of numerical values ​​that one of ordinary skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term "about" may indicate that the value is rounded to the nearest significant figure.

[0025] The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). Although suitable dimensions, ranges, and / or values ​​relating to various components, features, and / or specifications are disclosed, one of ordinary skill in the art, stimulated by this disclosure, will understand that the desired dimensions, ranges, and / or values ​​may deviate from those expressly disclosed.

[0026] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0027] The following detailed description should be read with reference to the drawings, in which like elements are designated by the same reference numerals throughout the different drawings. The detailed description and drawings, which are not necessarily to scale, depict exemplary embodiments and are not intended to limit the scope of the present disclosure. The exemplary embodiments shown are intended as examples only. Selected features of any exemplary embodiment may be incorporated into additional embodiments, unless expressly stated to the contrary.

[0028] FIG. 1 illustrates various organs within the digestive tract, including the stomach 102 , duodenum 104 , liver 106 , hepatic duct 108 , gallbladder 110 , common bile duct 112 , and pancreas 114 . Bile produced in the liver 106 flows through a series of hepatic ducts 108 and drains into one large duct called the common bile duct (CBD) 112. The CBD then connects to the duodenum 104, allowing bile to enter the duodenum for digestion. When the liver or bile ducts become blocked, bile cannot be drained normally and instead refluxes or accumulates in the liver 106. Blockage of the bile duct can cause jaundice, dark urine, nausea, and loss of appetite, potentially leading to serious conditions.

[0029] Endoscopic retrograde cholangiopancreatography (ERCP) can be used to diagnose and treat bile duct conditions, including gallstones, inflammatory strictures, leaks (e.g., due to trauma, surgery, etc.), and cancer. Bile duct obstruction can occur in many disorders of the biliary system, including liver disorders such as primary sclerosing cholangitis, stone formation, and scarring within the bile duct. Draining blocked fluid from the biliary system can be performed to treat the obstruction. Biliary drainage methods include the placement of plastic or metal stents to relieve the obstruction. In the case of gallstones causing obstruction within the duct, numerous products are also available to resolve this via ERCP. However, access to the bile duct via ERCP may be impossible for a variety of reasons, such as tumors blocking the passage, anatomical variations, or juxta-papillary diverticula.

[0030] If ERCP proves unsuccessful, percutaneous drainage (PTCD) can be performed. However, PTCD can be associated with complications such as bleeding and bile leakage. If subsequent internal drainage cannot be achieved, patients must accept long-term external biliary drainage, which is uncomfortable and can significantly impair quality of life.

[0031] Endoscopic ultrasound (EUS)-guided biliary drainage (BD) offers an alternative to surgery and percutaneous drainage for treating obstructive jaundice when ERCP drainage fails. A hepatogastrostomy (HGS) can be performed to connect the hepatic duct 108 to the stomach 102. This allows bile accumulation to drain into the stomach and may alleviate symptoms caused by bile accumulation, i.e., jaundice. However, the hepatic duct 108 and the stomach 102 are separated by a distance D, indicated by arrow 5 in FIG. 1 . The distance D between the organs may require a relatively long stent. Additionally, as the gastric muscles contract to churn food, the distance D between the hepatic duct 108 and the stomach wall of the stomach 102 changes from a relatively small distance D when the stomach is relaxed to a larger distance D when the stomach is contracted. In addition to the bending of the stomach wall, the stomach also undergoes peristaltic movements during digestion. It is understood that the relative motility of the stomach is not just linear, but is three-dimensionally complex. The distance between the target organs being joined, the relative movement of at least one of the organs, and normal body movements (e.g., twisting, running, jumping, etc.) can increase the chance of stent migration.

[0032] FIG. 2 illustrates an exemplary expandable medical device, i.e., a stent 120 (e.g., a drainage stent) including a first end region 122 (e.g., a proximal end region), a second end region 124 (e.g., a distal end region), and an intermediate region 126 extending between the first end region 122 and the second end region 124. The stent 120 may include one or more stent strut members 142 that form a tubular support structure. The multiple stent strut members 142 may extend helically, longitudinally, circumferentially, or otherwise along the stent 120. While FIG. 2 illustrates the stent strut members 142 extending along the entire length of the stent 120, in other examples, the multiple stent strut members 142 may extend along only a portion of the stent 120.

[0033] In some examples, stent 120 may be a self-expanding stent. Examples of self-expanding stents may include stents having one or more strut members 142 combined to form a rigid and / or semi-rigid tubular stent support structure. For example, the multiple stent strut members 142 of stent 120 may include wires or filaments that are braided, wrapped, intertwined, interwoven, weaved, knitted, looped (e.g., bobbinette style), or the like to form the tubular support structure. For example, exemplary stents disclosed herein may resemble braided stents, although this is not intended to limit possible stent configurations. Rather, the stents shown in the figures may be braided, knitted, wound, intertwined, interwoven, woven, looped (e.g., bobbinette style), or the like, to form a stent support structure. In various embodiments, the woven, braided, and / or knitted members may include a single filament woven against itself or multiple filaments woven against one another. In various embodiments, any of the woven, braided, and / or knitted members comprising the elongate tubular body may include a variety of different cross-sectional shapes (e.g., oval, circular, flattened, square, etc.).

[0034] Alternatively, stent 120 may be a monolithic structure formed from a cylindrical tubular member (such as a single cylindrical tubular member formed by laser cutting a Nitinol tubular member), with the remainder of the tubular member forming the strut members 142. Openings or gaps through the wall of stent 120 may be defined between adjacent strut members 142.

[0035] Stent 120, in the examples disclosed herein, can be constructed from a variety of materials. For example, stent 120 (e.g., self-expanding or balloon-expandable) can be constructed from a metal (e.g., Nitinol, Elgiloy®, etc.). In other cases, stent 120 can be constructed from a polymeric material (e.g., PET). In still other cases, stent 120 can be constructed from a combination of metallic and polymeric materials. Additionally, stent 120 can include bioabsorbable and / or biodegradable materials.

[0036] Additionally, stent 120 can be configured to transition between a first configuration (e.g., a constrained, contracted, or unexpanded configuration) and a second configuration (e.g., an unconstrained or expanded configuration). In the expanded configuration, first end region 122 of stent 120 can include retention members 128 that define first openings 130. Retention members 128 can be formed from stent strut members 142 used to form other portions of stent 120. For example, retention members 128 can be formed from the same stent strut members 142 used to form intermediate region 126.

[0037] 2 further illustrates that in the expanded configuration, second end region 124 of stent 120 can include a flared portion 132 having a second opening 136. In some instances, stent 120 may not include a flared portion 132. Rather, in some instances, intermediate region 126 can have a uniform outer diameter along its length.

[0038] Further, the intermediate region 126 of the stent 120 can have a circumference and a longitudinal axis. The intermediate region 126 of the stent 120 can extend between the flared portion 132 of the second end region 124 and the retention member 128 of the first end region 122. The stent 120 can define an internal open lumen (e.g., a passageway, a channel, etc.) extending from the first end region 122 to the second end region 124.

[0039] The retention member 128 may extend radially outward (e.g., substantially perpendicular) from the longitudinal axis of the intermediate region 126 to define a first surface 138a and a second surface 138b. In some examples, the first surface 138a, which may be the distal-facing surface of the retention member 128, is substantially parallel to the second surface 138b, which may be the proximal-facing surface of the retention member 128. The first surface 138a may be configured to atraumatically engage a tissue wall (e.g., an inner) of a first body lumen (e.g., the stomach or duodenum). Additionally, as described in more detail herein, the flared portion 132 (e.g., a flared flange structure) of the second end region 124 may include an outer surface 140 configured to atraumatically engage a tissue wall (e.g., an inner) of an adjacent or juxtaposed second body lumen (e.g., a bile duct). In the exemplary stent 120 shown in FIG. 2, surfaces 138a, 140 may prevent or limit movement / migration of the deployed stent 120 within or between the first and second body lumens.

[0040] 2 illustrates that in some examples, outer diameter D1 of retention member 128 may be greater than outer diameter D2 of flared portion 132. However, in other examples, outer diameter D1 of retention member 128 may be equal to outer diameter D2 of flared portion 132. Intermediate region 126 may have a constant outer diameter D3 extending between flared portion 132 and retention member 128, with diameter D3 of intermediate region 126 being smaller than diameters D1 and D2 of retention member 128 and flared portion 132, respectively. As described herein, in some examples, outer diameter D3 of intermediate region 126 may be substantially equal to outer diameter D2 of flared portion 132.

[0041] In some examples, diameter D1 can be about 5 mm to about 40 mm, or about 10 mm to about 35 mm, or about 15 mm to about 30 mm, or about 20 mm to about 25 mm, or about 10 mm to about 20 mm, or about 20 mm to about 35 mm. In some examples, diameter D2 can be about 2 mm to about 40 mm, or about 6 mm to about 30 mm, or about 10 mm to about 25 mm, or about 15 mm to about 20 mm, or about 6 mm to about 20 mm, or about 15 mm to about 35 mm. In some examples, diameter D3 can be about 2 mm to about 20 mm, or about 4 mm to about 18 mm, or about 6 mm to about 14 mm, or about 8 mm to about 12 mm, or about 6 mm to about 14 mm, or about 15 mm to about 25 mm.

[0042] In one embodiment, the second end region 124 of the stent 120 may include an atraumatic configuration in which the free ends of one or more adjacent woven, braided, or knitted strut members 142 are bent and connected to form a series of atraumatic looped ends 144. For example, each looped end 144a may be formed, for example, by mating and securing adjacent free ends of one or more filaments together, for example, by welding, soldering, adhesive bonding, clamps, crimpable hypotubes, or other suitable means as known in the art. In another embodiment, the second end region 124 of the elongated tubular support structure of the stent 120 may include an atraumatic configuration (e.g., looped ends) in which one or more strut members 142 are woven, braided, or knitted over a mandrel. Although shown schematically in FIG. 2, the plurality of loop ends 144a may include a variety of substantially angular configurations, including, by way of non-limiting example, semicircular, semi-elliptical, and other smoothly curved or substantially smoothly curved shapes.

[0043] Additionally, in some examples, the first end region 122 of the stent 120 may include unconnected free ends 146 of one or more woven, braided, or knitted strut members 142, which form sharp or pointed free ends of the strut members 142. As will be appreciated by one skilled in the art, the surfaces 138a of the retention members 128 may atraumatically engage the inner tissue wall of the first body lumen such that the free ends 146 extend into the first body lumen and do not contact the tissue wall.

[0044] As described herein, stent migration can cause serious complications, including death, in HGS patients. In the absence of tissue ingrowth-based adhesions in various anatomical regions, a deployed stent can migrate proximally into the stomach, causing leakage of bile contents into the peritoneum and resulting in peritonitis. In the presence of sufficient or excessive adhesions in the hepatic duct, the stent can migrate distally into the peritoneum, causing leakage of bile and gastric contents into the peritoneum, also resulting in peritonitis. Furthermore, a migrated stent can abrade the exterior of the stomach wall and other nearby organs or blood vessels without restriction. Anatomically, as described herein, stent migration can occur as a result of the hepatic duct being a generally static vessel, while the stomach is a highly motile organ. Therefore, one method of reducing stent migration can include exposing the bare metal portion of the stent to the tissue of the body lumen. In this case, the stent-supporting structure can provide a structure that promotes tissue ingrowth (e.g., hyperplasia) into the multiple gaps or openings in the stent-supporting structure. Tissue ingrowth may anchor the stent in place and reduce the risk of stent migration.

[0045] FIG. 2 illustrates that, in some instances, the tubular support structure of stent 120 may include one or more uncovered (e.g., bare) portions designed to promote tissue ingrowth (e.g., hyperplasia) into its interstices or openings. The uncovered portions are free of a membrane, coating, or other covering, and thus the interstices of the tubular support structure in the uncovered portions are open to tissue ingrowth. For example, FIG. 2 illustrates that stent 120 may include an uncovered portion 134. It will be appreciated that, in some instances, the uncovered portion 134 of the tubular support structure of stent 120 may include a flared portion 132 of stent 120. In other words, the flared portion 132 of stent 120 shown in FIG. 2 may be exposed (e.g., free of or without a membrane, coating, etc.), allowing tissue ingrowth through the interstices of the tubular support structure along the flared portion 132.

[0046] 2 further illustrates that stent 120 can include a membrane 150 (e.g., a coating, membrane coating, etc.) extending within the lumen of the tubular support structure of stent 120. For example, FIG. 2 illustrates that membrane 150 can extend across length L of tubular support structure of stent 120. The length L that membrane 150 extends within the lumen of tubular support structure of stent 120 can include a portion of intermediate region 126 and first end region 122 (including retention member 128). As described in more detail below, membrane 150 can extend from a separate attachment point along first end region 122 to a separate attachment point along intermediate region 126, thereby defining a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) that allows for the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach). In some examples, membrane 150 is an elastomeric or non-elastomeric material. For example, membrane 150 can be a polymeric material such as silicone, polyurethane, UE, PVDF, PTFE, ePTFE, ChronoFlex®, or a similar biocompatible polymeric material.

[0047] It will be further understood that stent 120 can be designed to include regions that do not include membrane 150 and regions that include membrane 150 in a configuration different from that shown in FIG. 2 . In other words, the lengths of uncovered portion 134 and covered portion L can be different from those shown in FIG. 2 . For example, uncovered portion 134 can be longer than that shown in FIG. 2 (e.g., the uncovered portion can extend into part or all of intermediate region 126). In other examples, a greater portion of stent 120 can include membrane 150. This corresponds to an increase in length L, whereby membrane 150 can extend into flared portion 132. It will be understood that as the proportion of stent 120 that includes membrane 150 increases, the proportion of stent 120 that does not include membrane 150 decreases, and vice versa. In some examples, the ratio of the covered portion L to the uncoated portion 134 can be about 9:1, or about 4:1, or about 7:3, or about 3:2, or about 1:1. The uncoated portion 134 can be designed to be more flexible than the uncoated portion 134, allowing for better trackability when placed in highly mobile areas of the body. It will be appreciated that by designing the stent 120 such that the length of the uncoated portion 134 is relatively greater relative to the covered portion L, a greater percentage of the overall stent length can be devoted to the luminal evacuation and anti-migration functions of the bare region. However, while a longer uncovered portion 134 may be more effective at preventing migration due to side branch shedding and ingrowth, a reduction in the covered portion L may reduce the effective length of the stent 120 that can bridge between anatomically separated organs (e.g., the distance from the stomach wall into the liver parenchyma). The uncovered portion 134 of the stent 120 must be sized to provide sufficient resistance to stent migration (through initial mechanical resistance and ultimately to prevent migration with additional tissue ingrowth), while still allowing the stent 120 to include sufficient covered portion L to bridge the distance between separated anatomical organs (e.g., the distance from the stomach wall into the liver parenchyma).

[0048] Figures 3-9 illustrate exemplary stents that may be similar in form and function to the stent 120 described above. For example, each of the stents illustrated in Figures 3-9 may include a membrane disposed within the lumen of the tubular support structure of the stent (e.g., as described with respect to Figure 2). The stents illustrated in Figures 3-9 may include various portions of the tubular support structure of the stent that are uncoated to promote tissue ingrowth therethrough.

[0049] FIG. 3 shows a cross-sectional view of an exemplary expandable medical device, i.e., stent 220. The exemplary stent 220 may be similar in form and function to the stent 120 described herein. For example, the stent 220 may include a first end region 222, a second end region 224, and an intermediate region 226. The stent 220 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 242 to form the tubular support structure of the stent 220. The stent 220 may also include a flared portion 232 disposed along the second end region 224. Additionally, the stent may include a retention member 228 disposed along the first end region 222.

[0050] Figure 3 further illustrates that stent 220 may include membrane 250 that extends along a portion of the inner surface of strut members 242 that define the tubular support structure of stent 220. In other words, Figure 3 illustrates that stent 220 may include membrane 250 that extends within the inner lumen of the tubular support structure of stent 220, thereby allowing membrane 250 to be attached at various locations along the inner surface of the tubular support structure of stent 220.

[0051] For example, Figure 3 shows that membrane 250 may be attached to the tubular support structure of stent 220 at first separate circumferential attachment point 252 and second separate circumferential attachment point 254. It will be appreciated that membrane 250 may be attached circumferentially along the inner surface of the tubular support structure of stent 220 at both first separate circumferential attachment point 252 and second separate circumferential attachment point 254. As will be further appreciated from Figure 3, membrane 250 may extend spaced apart from inner surface 256 of strut member 242 (which forms the tubular support structure of stent 220) along a portion of the stent structure extending between first separate circumferential attachment point 252 and second separate circumferential attachment point 254.

[0052] 3 illustrates that membrane 250 may be fixedly attached to the inner surface of the tubular support structure of stent 220 along a portion of the tubular support structure of stent 220 identified as length X1. FIG. 3 illustrates that membrane 250 may be adhered (e.g., affixed, secured, etc.) to the inner surface of strut members 242 along length X1. As can be seen from FIG. 3, length X1 of the tubular support structure of stent 220 may include retention members 228. It will be appreciated that the portion of the tubular support structure of stent 220 described above, including membrane 250 (e.g., covering) attached to strut members 242, may function to prevent tissue from growing into the interstices or openings thereof. For example, the strut members 242 along the length X1 of the tubular support structure of the stent 220, to which the membrane 250 is attached, may extend across multiple gaps in the tubular support structure of the stent 220 and may prevent tissue ingrowth along the individual surfaces of the membrane 250 and the strut members 242 and the multiple gaps therebetween.

[0053] It will further be appreciated that strut members 242 of the tubular support structure of stent 220 to which membrane 250 is not attached (e.g., the portion of membrane 250 extending along flared portion 232 and the portion of membrane 250 extending along intermediate region 226 between first and second distinct circumferential attachment points 252 and 254 of tubular support structure of stent 220) may allow tissue to grow around, between, throughout, within, etc. In other words, FIG. 3 illustrates multiple "tissue ingrowth regions" defined along both flared portion 232 and intermediate region 226 (between first and second distinct circumferential attachment points 252 and 254) of tubular support structure of stent 220. The tissue ingrowth region may be defined as the space between the inner surface 256 of the tubular support structure of the stent 220 and the outer surface of the membrane 250 extending between the attachment points 252 / 254. As described herein, the uncovered or bare portions of the tubular support structure of the stent 220 may promote tissue ingrowth to provide a structure that anchors the stent 220 in place and reduces the risk of stent migration.

[0054] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 250 to the inner surface of the tubular support structure of stent 220, membrane 250 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0055] FIG. 4 shows a cross-sectional view of another exemplary expandable medical device, namely, stent 320. The exemplary stent 320 may be similar in form and function to the stent 120 described herein. For example, the stent 320 may include a first end region 322, a second end region 324, and an intermediate region 326. The stent 320 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 342 to form the tubular support structure of the stent 320. The stent 320 may also include a flared portion 332 disposed along the second end region 324. Additionally, the stent may include a retention member 328 disposed along the first end region 322.

[0056] Figure 4 further illustrates that stent 320 may include membrane 350 that extends along a portion of the inner surface of strut members 342 that define the tubular support structure of stent 320. In other words, Figure 4 illustrates that stent 320 may include membrane 350 that extends within the inner lumen of the tubular support structure of stent 320, thereby allowing membrane 350 to be attached at various locations along the inner surface of the tubular support structure of stent 320.

[0057] For example, Figure 4 shows that membrane 350 may be attached to the tubular support structure of stent 320 at first separate circumferential attachment point 352 and second separate circumferential attachment point 354. It will be appreciated that membrane 350 may be attached circumferentially along the inner surface of the tubular support structure of stent 320 at both first separate circumferential attachment point 352 and second separate circumferential attachment point 354. As will be further appreciated from Figure 4, membrane 350 may extend away from inner surface 356 of strut member 342 (which forms the tubular support structure of stent 320) along a portion of the stent structure extending between first separate circumferential attachment point 352 and second separate circumferential attachment point 354.

[0058] 4 further illustrates that membrane 350 may be fixedly attached to the inner surface of the tubular support structure of stent 320 along a portion of the tubular support structure of stent 320 identified as length X2. FIG. 4 illustrates that membrane 350 may be adhered (e.g., affixed, secured, etc.) to the inner surface of strut members 342 along length X2. As can be seen from FIG. 4, length X2 of the tubular support structure of stent 320 may include retention members 328. It will be appreciated that the portion of the tubular support structure of stent 320 described above, including membrane 350 (e.g., covering) attached to strut members 342, may function to prevent tissue from growing into the interstices or openings thereof. For example, the strut members 342 along the length X2 of the tubular support structure of the stent 320, to which the membrane 350 is attached, may extend across multiple gaps in the tubular support structure of the stent 320 and may prevent tissue ingrowth along the individual surfaces of the membrane 350 and strut members 342 and the multiple gaps therebetween.

[0059] It will further be appreciated that strut members 342 of the tubular support structure of stent 320 to which membrane 350 is not attached (e.g., the portion of membrane 350 extending along flared portion 332 and the portion of membrane 350 extending along intermediate region 326 between first and second distinct circumferential attachment points 352 and 354 of tubular support structure of stent 320) may allow tissue to grow around, between, throughout, within, etc. In other words, FIG. 4 illustrates multiple "tissue ingrowth regions" defined along both flared portion 332 and intermediate region 326 (between first and second distinct circumferential attachment points 352 and 354) of tubular support structure of stent 320. The tissue ingrowth region may be defined as the space between the inner surface 356 of the tubular support structure of the stent 320 and the outer surface of the membrane 350 extending between the discrete attachment points 352 / 354. As described herein, the uncovered or bare portions of the tubular support structure of the stent 320 may promote tissue ingrowth to provide a structure that anchors the stent 320 in place and reduces the risk of stent migration.

[0060] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 350 to the inner surface of the tubular support structure of stent 320, membrane 350 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0061] FIG. 5 shows a cross-sectional view of another exemplary expandable medical device, namely, stent 420. The exemplary stent 420 may be similar in form and function to stent 120 described herein. For example, stent 420 may include a first end region 422, a second end region 424, and an intermediate region 426. Stent 420 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 442 to form the tubular support structure of stent 420. Stent 420 may also include a flared portion 432 disposed along second end region 424. Additionally, the stent may include a retention member 428 disposed along first end region 422.

[0062] Figure 5 further illustrates that stent 420 may include membrane 450 that extends along a portion of the inner surface of strut members 442 that define the tubular support structure of stent 420. In other words, Figure 5 illustrates that stent 420 may include membrane 450 that extends within the inner lumen of the tubular support structure of stent 420, thereby allowing membrane 450 to be attached at various locations along the inner surface of the tubular support structure of stent 420.

[0063] For example, Figure 5 shows that membrane 450 may be attached to the tubular support structure of stent 420 at first separate circumferential attachment point 452 and second separate circumferential attachment point 454. It will be appreciated that membrane 450 may be attached circumferentially along the inner surface of the tubular support structure of stent 420 at both first separate circumferential attachment point 452 and second separate circumferential attachment point 454. As will be further appreciated from Figure 5, membrane 450 may extend away from inner surface 456 of strut member 442 (which forms the tubular support structure of stent 420) along a portion of the stent structure extending between first separate circumferential attachment point 452 and second separate circumferential attachment point 454.

[0064] 5 further illustrates that membrane 450 may be fixedly attached to the inner surface of the tubular support structure of stent 420 along a portion of the tubular support structure of stent 420 identified as length X3. FIG. 5 illustrates that membrane 450 may be adhered (e.g., affixed, secured, etc.) to the inner surface of strut members 442 along length X3. As can be seen from FIG. 4, length X3 of the tubular support structure of stent 420 may include retention members 428. It will be appreciated that the portion of the tubular support structure of stent 420 described above, including membrane 450 (e.g., covering) attached to strut members 442, may function to prevent tissue from growing into the interstices or openings thereof. For example, the strut members 442 along the length X3 of the tubular support structure of the stent 420, to which the membrane 450 is attached, may extend across multiple gaps in the tubular support structure of the stent 420 and may prevent tissue ingrowth along the individual surfaces of the membrane 450 and strut members 442 and the multiple gaps therebetween.

[0065] It will further be appreciated that strut members 442 of the tubular support structure of stent 420 to which membrane 450 is not attached (e.g., the portion of membrane 450 extending along flared portion 432 and the portion of membrane 450 extending along intermediate region 426 between first and second distinct circumferential attachment points 452 and 454 of tubular support structure of stent 420) may allow tissue to grow around, between, throughout, within, etc. In other words, FIG. 5 illustrates multiple "tissue ingrowth regions" defined along both flared portion 432 and intermediate region 426 (between first and second distinct circumferential attachment points 452 and 454) of tubular support structure of stent 420. The tissue ingrowth region may be defined as the space between the inner surface 456 of the tubular support structure of the stent 420 and the outer surface of the membrane 450 extending between the discrete attachment points 452 / 454. As described herein, the uncovered or bare portions of the tubular support structure of the stent 420 may promote tissue ingrowth to provide a structure that anchors the stent 420 in place and reduces the risk of stent migration.

[0066] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 450 to the inner surface of the tubular support structure of stent 420, membrane 450 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0067] FIG. 6 shows a cross-sectional view of another exemplary expandable medical device, namely, stent 520. The exemplary stent 520 may be similar in form and function to the stent 120 described herein. For example, the stent 520 may include a first end region 522, a second end region 524, and an intermediate region 526. The stent 520 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 542 to form the tubular support structure of the stent 520. The stent 520 may also include a flared portion 532 disposed along the second end region 524. Additionally, the stent may include a retention member 528 disposed along the first end region 522.

[0068] Figure 6 further illustrates that stent 520 may include membrane 550 that extends along a portion of the inner surface of strut members 542 that define the tubular support structure of stent 520. In other words, Figure 6 illustrates that stent 520 may include membrane 550 that extends within the inner lumen of the tubular support structure of stent 520, thereby allowing membrane 550 to be attached at various locations along the inner surface of the tubular support structure of stent 520.

[0069] For example, Figure 6 shows that membrane 550 may be attached to the tubular support structure of stent 520 at first separate circumferential attachment point 552 and second separate circumferential attachment point 554. It will be appreciated that membrane 550 may be attached circumferentially along the inner surface of the tubular support structure of stent 520 at both first separate circumferential attachment point 552 and second separate circumferential attachment point 554. As will be further appreciated from Figure 6, membrane 550 may extend away from inner surface 556 of strut member 542 (which forms the tubular support structure of stent 520) along a portion of the stent structure extending between first separate circumferential attachment point 552 and second separate circumferential attachment point 554.

[0070] It will be appreciated that the portion of the tubular support structure of the stent 520 described above, including the membrane 550 (e.g., covering) attached to the strut members 542, may function to prevent tissue from growing into the interstices or openings thereof. For example, the strut members 542 of the tubular support structure of the stent 520, to which the membrane 550 is attached, may extend across the interstices of the tubular support structure of the stent 520 and prevent tissue ingrowth along the individual surfaces of the membrane 550 and strut members 542 and the interstices therebetween.

[0071] It will further be appreciated that strut members 542 of the tubular support structure of stent 520 to which membrane 550 is not attached (e.g., the portion of membrane 550 extending along flared portion 532 and the portion of membrane 550 extending along intermediate region 526 between first and second distinct circumferential attachment points 552 and 554 of tubular support structure of stent 520) may allow tissue to grow around, between, throughout, within, etc. In other words, FIG. 6 illustrates multiple "tissue ingrowth regions" defined along both flared portion 532 and intermediate region 526 (between first and second distinct circumferential attachment points 552 and 554) of tubular support structure of stent 520. The tissue ingrowth region may be defined as the space between the inner surface 556 of the tubular support structure of the stent 520 and the outer surface of the membrane 550 extending between the discrete attachment points 552 / 554. As described herein, the uncovered or bare portions of the tubular support structure of the stent 520 may promote tissue ingrowth to provide a structure that anchors the stent 520 in place and reduces the risk of stent migration.

[0072] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 550 to the inner surface of the tubular support structure of stent 520, membrane 550 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0073] FIG. 7 shows a cross-sectional view of another exemplary expandable medical device, namely, a stent 620. The exemplary stent 620 may be similar in form and function to the stents 620 described herein. For example, the stent 620 may include a first end region 622, a second end region 624, and an intermediate region 626. The stent 620 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 642 to form the tubular support structure of the stent 620. The stent 620 may also include a flared portion 632 disposed along the second end region 624. Additionally, the stent may include a retention member 628 disposed along the first end region 622.

[0074] Figure 7 further illustrates that stent 620 may include membrane 650 that extends along a portion of the inner surface of strut members 642 that define the tubular support structure of stent 620. In other words, Figure 7 illustrates that stent 620 may include membrane 650 that extends within the inner lumen of the tubular support structure of stent 620, thereby allowing membrane 650 to be attached at various locations along the inner surface of the tubular support structure of stent 620.

[0075] 7 shows that membrane 650 may be attached to the tubular support structure of stent 620 at first distinct circumferential attachment points 652 and second distinct circumferential attachment points 654. It will be appreciated that membrane 650 may be attached circumferentially along the inner surface of the tubular support structure of stent 620 at both first distinct circumferential attachment points 652 and second distinct circumferential attachment points 654.

[0076] FIG. 7 further illustrates that membrane 650 may be fixedly attached to the inner surface of tubular support structure 620 along portions of tubular support structure 620, identified as lengths X4, X5, and X6. Length X6, along which membrane 650 is fixedly attached to the inner surface of tubular support structure 620, may be similar to length X2 described with respect to FIG. 4. FIG. 7 illustrates that membrane 650 may be adhered (e.g., affixed, secured, etc.) to the inner surface of strut members 642 along lengths X4, X5, and X6 of tubular support structure 620. As can be seen from FIG. 7, length X6 of tubular support structure 620 may include retention members 628. It will be appreciated that the portions of tubular support structure 620 described above, including membrane 650 (e.g., covering) attached to strut members 642, may function to prevent tissue from growing into the interstices or openings thereof. For example, the strut members 642 along the lengths X4, X5, X6 of the tubular support structure of the stent 620, to which the membrane 650 is attached, may extend across multiple gaps in the tubular support structure of the stent 620 and may prevent tissue ingrowth along the individual surfaces of the membrane 650 and strut members 642 and the multiple gaps therebetween.

[0077] It will further be appreciated that strut members 642 of the tubular support structure of stent 620 to which membrane 650 is not attached (e.g., the portion of membrane 650 extending along flared portion 632, and the portion of membrane 650 extending between first distinct circumferential attachment point 352 and length X4, between lengths X4 and X5, between lengths X5 and X6, and along length X6 along intermediate region 626) may allow tissue to grow around, between, throughout, within, etc., such strut members 642. In other words, FIG. 7 illustrates multiple "tissue ingrowth regions" defined along both flared portion 632 and intermediate region 626 (between first distinct circumferential attachment point 652 and length X4, between lengths X4 and X5, and between lengths X5 and X6) of the tubular support structure of stent 620. The tissue ingrowth region may be defined as the space between the inner surface 656 of the tubular support structure of the stent 620 and the outer surface of the membrane 650 extending between the discrete attachment points 652 / 654. As described herein, the uncovered or bare portions of the tubular support structure of the stent 620 may promote tissue ingrowth to provide a structure that anchors the stent 620 in place and reduces the risk of stent migration.

[0078] It will be appreciated that in some instances, length X4 may be substantially equal to length X5. However, in other instances, length X4 may differ from length X5. For example, length X4 may be shorter than length X5. In other instances, length X5 may be shorter than length X4. Furthermore, it will be appreciated that the distance that membrane 650 extends away from the inner surface 656 of stent 620 may vary depending on the length of X4 or X5. For example, it will be appreciated that decreasing length X4 or X5 may result in an elongation of the unattached portion of membrane 650 extending between the portions of membrane 650 that remain attached to the inner surface 656 of stent 620. A longer unattached portion of membrane 650 allows membrane 650 to extend further away from inner surface 656, thereby creating a larger ingrowth “pocket” that allows for a greater amount of tissue ingrowth to anchor stent 120.

[0079] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 650 to the inner surface 656 of the tubular support structure of stent 620, membrane 650 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0080] FIG. 8 shows a cross-sectional view of another exemplary expandable medical device, namely, stent 720. The exemplary stent 720 may be similar in form and function to the stent 120 described herein. For example, the stent 720 may include a first end region 722, a second end region 724, and an intermediate region 726. The stent 720 may be formed from one or more braided, knitted, wound, intertwined, interwoven, woven, or looped (e.g., bobbinette-style) strut members 742 to form the tubular support structure of the stent 720. The stent 720 may also include a flared portion 732 disposed along the second end region 724. Additionally, the stent may include a retention member 728 disposed along the first end region 722.

[0081] Figure 8 further illustrates that stent 720 may include membrane 750 that extends along a portion of the inner surface of strut members 742 that define the tubular support structure of stent 720. In other words, Figure 8 illustrates that stent 720 may include membrane 750 that extends within the inner lumen of the tubular support structure of stent 720, thereby allowing membrane 750 to be attached at various locations along the inner surface of the tubular support structure of stent 720.

[0082] 8 shows that membrane 750 may be attached to the tubular support structure of stent 720 at first distinct circumferential attachment points 752 and second distinct circumferential attachment points 754. It will be appreciated that membrane 750 may be attached circumferentially along the inner surface of the tubular support structure of stent 720 at both first distinct circumferential attachment points 752 and second distinct circumferential attachment points 754.

[0083] Additionally, FIG. 8 illustrates an example of an arrangement in which membrane 750 is attached and detached in longitudinal stripes to the tubular support structure of stent 720. The striped arrangement of the unattached portions of membrane 750 is further illustrated in the cross-sectional view taken along line 9-9 in FIG. 8. For example, the cross-sectional view in FIG. 9 illustrates four portions 750a, 750b, 750c, and 750d of membrane 750 that are not attached to the tubular support structure of stent 720. It can be seen from FIG. 9 that each of the four portions 750a, 750b, 750c, and 750d of membrane 750 that are not attached to the tubular support structure of stent 720 extends inward toward the longitudinal axis 764 of stent 720. FIG. 9 illustrates that each of the four portions 750a, 750b, 750c, and 750d of membrane 750 forms a space between the inner surface of stent 720 and the outward-facing surface of membrane 750. 9 illustrates that membrane 750 may be connected to an inner surface 756 of the tubular support structure of stent 720 along a portion of the stent extending between four portions 750a, 750b, 750c, 750d of membrane 750 that are not attached to the tubular support structure of stent 720. In other words, FIG. 9 illustrates that membrane 750 may be circumferentially continuous so as to define a lumen 762 that extends longitudinally along the tubular support structure of stent 720. As can be further appreciated from FIG. 8, membrane 750 may extend spaced apart from inner surfaces 756 of strut members 742 (which form the tubular support structure of stent 720) along a portion of the stent structure extending between first distinct circumferential attachment point 752 and second distinct circumferential attachment point 754.

[0084] 9 illustrates that the membrane 750 may be connected to the inner surface 756 of the tubular support structure of the stent 720 along the portion of the stent between the four portions 750a, 750b, 750c, and 750d of the membrane 750 that are not attached to the tubular support structure of the stent 720. Furthermore, FIG. 8 illustrates that the membrane 750 may be attached along a portion of the tubular support structure of the stent 320, identified as length X7. FIG. 9 illustrates that the membrane 750 may be adhered (e.g., affixed, secured, etc.) to the inner surface of the strut members 742 along length X7. As can be seen from FIG. 8, the length X7 of the tubular support structure of the stent 720 may include the retention members 728. It will be appreciated that the portion of the tubular support structure of the stent 720 described above, including the membrane 750 (e.g., covering) attached to the strut members 742, may function to prevent tissue from growing into the interstices or openings therein. For example, the strut members 742 along the length X7 of the tubular support structure of the stent 720, to which the membrane 750 is attached, may extend across multiple gaps in the tubular support structure of the stent 720 and may prevent tissue ingrowth along the individual surfaces of the membrane 750 and strut members 742 and the multiple gaps therebetween.

[0085] It will further be appreciated that strut members 742 of the tubular support structure of stent 720 to which membrane 750 is not attached (e.g., the portion of membrane 750 extending along flaring portion 732 and the portion of membrane 750 extending between the four portions 750a, 750b, 750c, 750d of membrane 750 that are not attached to the tubular support structure of stent 720) may allow tissue to grow around, between, throughout, within, etc. In other words, Figures 8-9 show multiple "tissue ingrowth regions" defined along both flaring portion 732 and intermediate region 726 of the tubular support structure of stent 720 (between the four portions 750a, 750b, 750c, 750d of membrane 750 that are not attached to the tubular support structure of stent 720). The tissue ingrowth region may be defined as the space between the inner surface 756 of the tubular support structure of the stent 720 and the outer surface of the membrane 750. As described herein, the uncovered or bare portions of the tubular support structure of the stent 720 may promote tissue ingrowth to provide a structure that anchors the stent 720 in place and reduces the risk of stent migration.

[0086] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 750 to the inner surface of the tubular support structure of stent 720, membrane 750 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0087] As described herein, the exemplary stents described herein can be designed to allow leak-free drainage from one anatomical structure (e.g., the hepatic duct) to another anatomical structure (e.g., the stomach) while allowing tissue ingrowth into the stent to prevent stent migration. For example, FIG. 10 shows the flared end 132 of an exemplary stent 120 positioned within the hepatic duct 116 of the liver 106. FIG. 10 also shows the retention member 128 positioned within the stomach 102.

[0088] As described herein, the uncovered portions of the stent 120 may promote desirable tissue ingrowth to prevent migration of the stent 120 after it has been properly positioned within the body. For example, exemplary stent configurations disclosed herein may provide resistance to migration by selectively allowing tissue ingrowth along the uncovered portions of the stent. For example, the atraumatic surface 138a of the retention member 128 (shown contacting the inner wall 118 of the stomach 102) and along the flared portion 132 of the stent 120 may provide resistance to migration by selectively allowing tissue ingrowth along these portions. As described herein, other stent designs disclosed herein may include additional regions to allow tissue ingrowth. Furthermore, FIG. 10 illustrates that the stent 120 may allow bile (or other bodily fluids) to flow from the hepatic duct 116 to the stomach 102 through the lumen of the membrane 150.

[0089] The exemplary stents shown in Figures 2-9 may contemplate a braided stent design utilized to allow leak-free drainage from one anatomical structure (e.g., the hepatic duct) to another anatomical structure (e.g., the stomach) while allowing tissue ingrowth into the stent to prevent stent migration. Additional stent designs are contemplated that allow leak-free drainage from one anatomical structure (e.g., the hepatic duct) to another anatomical structure (e.g., the stomach) while also allowing tissue ingrowth into the stent to prevent stent migration. For example, the braided stents described herein may be utilized for similar purposes as the stents described in Figures 2-9.

[0090] FIG. 11 illustrates an exemplary expandable medical device, a braided stent 820. The stent 820 may have a first end 822, a second end 824, and an intermediate region 826 extending between the first end 822 and the second end 824. The stent 820 may include a lumen extending from a first opening adjacent the first end 822 to a second opening adjacent the second end 824. The stent 820 may be made from at least one filament that forms open cells and a twisted knit stitch. In some instances, the stent 820 may be formed from only a single filament that is interwoven with itself to form the open cells and the twisted knit stitch. In some cases, the filament may be a monofilament, while in other cases, the filament may be two or more filaments that are wrapped, braided, or woven together.

[0091] It is contemplated that stent 820 may be made from several different materials, such as, but not limited to, metals, metal alloys, shape memory alloys, and / or polymers, as desired, allowing stent 820 to expand into a certain shape when correctly positioned within the body. In some cases, materials may be selected to also allow stent 820 to be relatively easily removed. For example, stent 820 may be formed from alloys such as, but not limited to, Nitinol and Elgiloy®. Depending on the materials selected for construction, stent 820 may be self-expanding (i.e., configured to automatically radially expand when unconstrained). In some embodiments, fibers may be used to fabricate stent 820, such as a composite fiber having an outer shell made of Nitinol with a platinum core. It is further contemplated that stent 820 may be formed from a polymer, including, but not limited to, polyethylene terephthalate (PET).

[0092] As shown in FIG. 11, the stretching of the disclosed braid pattern allows stent 820 to change length without significantly reducing diameter, and because of the availability of excess material "stored" in the design, it can maintain radial force, effectively allowing it to be used as an "infinite" braid throughout the entire design range. FIGS. 11-12 illustrate the performance of braided stent 820 as it moves between a relaxed, longitudinally contracted state (shown in FIG. 11) and an extended state (shown in FIG. 12). Braided stent 820 can accommodate changes in length without changing diameter, as shown in FIGS. 11-12. Thus, stent 820 can have a first longitudinal length and a first diameter in the relaxed, expanded configuration (FIG. 11), and a second longitudinal length and a second diameter in the extended configuration (FIG. 12), where the first longitudinal length is shorter than the second longitudinal length and the first and second diameters are substantially the same. As a result, stent 820 can conform to more movement between two anatomical structures and may perform better in areas of motility, such as the HGS procedure described above, while maintaining a substantially constant lumen diameter to allow fluid flow through the stent. Stent 820 may behave like a spring in its deployed, relaxed, and fully expanded configurations.

[0093] Figure 13 shows a cross-sectional view of stent 820 shown in Figure 11. Figure 13 further illustrates that stent 820 may include membrane 850 extending along a portion of the inner surface of braided filament members 842 that define the braided support structure of stent 820. In other words, Figure 13 illustrates that stent 820 may include membrane 850 extending within the inner lumen of the braided support structure of stent 820, whereby membrane 850 may be attached at various locations along the inner surface of the braided support structure of stent 820.

[0094] For example, Figure 13 shows that membrane 850 may be attached to the knitted support structure of stent 820 at first discrete circumferential attachment location 852 and second discrete circumferential attachment location 854. It will be appreciated that membrane 850 may be attached around the entire circumference along the inner surface of the knitted support structure of stent 820 at both first discrete circumferential attachment location 852 and second discrete circumferential attachment location 854. As will be further appreciated from Figure 13, membrane 850 may extend spaced apart from inner surface 856 of knitted filament member 842 (forming the knitted support structure of stent 820) along a portion of the stent structure extending between first discrete circumferential attachment location 852 and second discrete circumferential attachment location 854.

[0095] Additionally, FIG. 13 illustrates that membrane 850 can be fixedly attached to the inner surface of the tubular support structure of stent 820 along retention member 828 of the knitted support structure of stent 820. FIG. 13 illustrates that membrane 850 can be adhered (e.g., affixed, secured, etc.) to the inner surface of knitted filament member 842 along retention member 828. It will be appreciated that the portions of the knitted support structure of stent 820 described above, including membrane 850 attached to (e.g., covering) knitted filament member 842, can act to prevent tissue from growing into its interstices or openings. For example, knitted filament member 842 along retention member 828 of the knitted support structure of stent 820, to which membrane 850 is attached, can extend across interstices in the knitted support structure of stent 820 and prevent tissue ingrowth along the individual surfaces of membrane 850 and knitted filament member 842 and the interstices therebetween.

[0096] It will be further understood that tissue may be able to grow around, between, throughout, within, etc., the knitted filament members 842 of the tubular support structure of the stent 820 where the membrane 850 is not attached. In other words, FIG. 13 shows multiple "tissue ingrowth regions" defined along the intermediate region 826 of the knitted support structure of the stent 820. Some tissue ingrowth regions may be defined as the space between the inner surface 856 of the tubular support structure of the stent 820 and the outer surface of the membrane 850 extending between the discrete attachment points 852 / 854. As described herein, the uncovered or bare portions of the knitted support structure of the stent 820 may promote tissue ingrowth to anchor the stent 820 in place and provide a structure that reduces the risk of stent migration.

[0097] Furthermore, as will be understood from the description herein of the separate attachment points of membrane 850 to the inner surface of the knitted support structure of stent 820, membrane 850 may define a leak-tight passageway (e.g., a channel, lumen, tunnel, etc.) to allow the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0098] Figure 14 shows a cross-sectional view of the stent 820 shown in Figure 12. Figure 14 illustrates membrane 850 of knitted stent 820 as knitted stent 820 moves between a relaxed, longitudinally contracted state (shown in Figure 11) and an elongated state (shown in Figure 12). Figure 14 illustrates that membrane 850 can move between a relaxed state (Figure 11) and a tensioned state when in an elongated state (Figure 12). It will be appreciated that membrane 850 can define a leak-tight passageway (e.g., channel, lumen, tunnel, etc.) to allow for the evacuation of bodily materials when in the relaxed state (Figure 13) and while in the elongated state (Figure 14).

[0099] FIG. 15 illustrates another exemplary expandable medical device, stent 920. Stent 920 may be similar in form and function to stent 820 described herein. Stent 920 may include a first end 922 and a second end 924. Stent 920 may include a lumen extending between first end 922 and second end 924. Additionally, FIG. 15 illustrates that stent 920 may include a first knitted region W and a second knitted region Z. FIG. 15 further illustrates that stent 920 may include a coated region Y disposed between first knitted region W and second knitted region Z. Coated region Y may be defined as a region of stent 920 that includes knitted stent filaments 942 encapsulated within a coating. The coating of stent filaments 942 along encapsulated coated region Y may prevent region Y of stent 920 from elongating. It will be appreciated that the first knitted region Y and the second knitted region Z may be capable of stretching similar to the stent 820 described herein.

[0100] Figure 16 shows a cross-sectional view of the stent 820 shown in Figure 15. Figure 16 further illustrates that the stent 920 may include a membrane 950 that extends along a portion of the inner surface of the braided stent filaments 942 that define the braided support structure of the stent 920. In other words, Figure 16 illustrates that the stent 920 may include the membrane 950 that extends within the inner lumen of the braided support structure of the stent 920, thereby allowing the membrane 950 to be attached at various locations along the inner surface of the braided support structure of the stent 920.

[0101] 16 illustrates that membrane 950 may be attached to the knitted support structure of stent 920 at a first discrete circumferential attachment location 952 and a second discrete circumferential attachment location 954. It will be appreciated that membrane 950 may be attached around the entire circumference along the inner surface of the knitted support structure of stent 920 at both first discrete circumferential attachment location 952 and second discrete circumferential attachment location 954. As can be further appreciated from FIG. 16 , membrane 950 may extend spaced apart from inner surface 956 of knitted filament member 942 (forming the knitted support structure of stent 920) along a portion of the stent structure extending between first discrete circumferential attachment location 952 and second discrete circumferential attachment location 954.

[0102] Additionally, the braided stent filaments 942 along the retention members 928 of the braided support structure of the stent 920 may include a coating that extends across the interstices of the braided support structure of the stent 920 along the retention members 928. The coating may prevent tissue ingrowth along the individual surfaces of the coating and braided stent filaments 942 and the interstices therebetween. Furthermore, the coating across the braided filaments 942 defining the retention members 928 may provide a leak-tight surface. Thus, the coated braided filaments 942 defining the retention members 928 together with the membrane 950 define a leak-tight passageway (e.g., channel, lumen, tunnel, etc.) that allows for the evacuation of bodily substances (e.g., bile) from one anatomical organ (e.g., the liver) to another anatomical organ (e.g., the stomach).

[0103] It will further be appreciated that tissue may be allowed to grow around, between, throughout, within, etc., the knitted filament members 942 of the knitted support structure of the stent 920 where the membrane 950 is not attached. In other words, FIG. 16 shows multiple "tissue ingrowth regions" defined along the intermediate region 926 of the knitted support structure of the stent 920. Some tissue ingrowth regions may be defined as the space between the inner surface 956 of the tubular support structure of the stent 920 and the outer surface of the membrane 950 extending between the discrete attachment points 952 / 954. As described herein, the uncovered or bare portions of the knitted support structure of the stent 920 may promote tissue ingrowth to anchor the stent 920 in place and provide a structure that reduces the risk of stent migration.

[0104] It will be understood that for any of the exemplary stent configurations described herein, coating and / or encapsulating a greater percentage of the stent strut members may result in a less flexible stent design. In other words, the exemplary stents disclosed herein exhibit stent designs with different proportions (e.g., ratios) of uncoated (e.g., bare) stent strut members to covered (e.g., with a membrane, coating, etc.) stent strut members. It will be understood that these designs may vary in flexibility, such that stents with a lower percentage of coated stent strut members are more flexible.

[0105] In addition to the HGS procedures described herein, it will be understood that the exemplary stents described herein can be used in other medical procedures. For example, the stent designs described herein can be utilized in a gastrojejunal (GJ) bypass procedure. One GJ procedure involves inserting one end of a stent into the stomach wall and the other end into a distal portion of the small intestine. The stent forms an anastomosis between the small intestine and the stomach, effectively diverting stomach contents directly into the small intestine. Because both the stomach wall and the intestine undergo peristaltic movement, this is considered a high-motility application that could benefit from a stent, which could achieve a bypass while allowing for an adaptable channel that maintains its diameter during peristalsis.

[0106] U.S. Provisional Patent Application No. 63 / 246,376, filed September 21, 2021, and U.S. Patent Application No. 17,941,867, filed September 9, 2022, are incorporated by reference herein in their entirety for all purposes. These applications describe stents and related methods for implantation in a body lumen.

[0107] Stents, delivery systems, and their various components may be made from metals, metal alloys, polymers (some examples of which are disclosed below), metal-polymer composites, ceramics, combinations thereof, etc., or other suitable materials. Some examples of suitable metals and metal alloys include stainless steels such as 304V, 304L, and 316LV stainless steel, mild steel, nickel-titanium alloys such as linear elastic and / or superelastic 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, cobalt-chromium alloys, cobalt-chromium-molybdenum alloys, platinum-strengthened stainless steels, titanium, combinations thereof, etc., or other suitable materials.

[0108] Other examples of some suitable polymers for stents or delivery systems include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, e.g., DELRIN® available from DuPont), polyether block esters, polyurethanes (e.g., Polyurethane 85A), polypropylene (PP), polyvinyl chloride (PVC), polyether-esters (e.g., ARNITEL® available from DSM Engineering Plastics), ether or ester-based copolymers (e.g., butylene / poly(alkylene ether) phthalates and / or other polyester elastomers, such as HYTREL® available from DuPont), polyamides (e.g., DURETHAN® available from Bayer, or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide / ethers, polyether block amides (PEBA, e.g., available under the trade name PEBAX®), ethylene vinyl acetate, and the like. copolymer (EVA), silicone, polyethylene (PE), Marlex high density polyethylene, Marlex low density polyethylene, linear low density polyethylene (e.g., REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO) , polyparaphenylene terephthalamide (e.g., KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grillon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (e.g., SIBS and / or SIBS 50A), polycarbonate, ionomers, biocompatible polymers, and other suitable materials.or mixtures, combinations, copolymers, polymer / metal composites, etc.

[0109] In at least some embodiments, portions or all of the stent or delivery system may also be doped with, fabricated from, or otherwise include radiopaque materials. Radiopaque materials are generally understood to be materials that are opaque to RF energy in the wavelength range spanning x-rays to gamma rays (thicknesses of <0.005 inches (0.127 mm)). These materials are capable of producing a relatively dark image on a fluoroscopy screen compared to the bright image produced by non-radiopaque materials such as tissue. This relatively bright image aids the user of the stent or delivery system in determining its location. Some examples of radiopaque materials may include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloys, polymeric materials filled with radiopaque fillers, and the like. Additionally, other radiopaque marker bands and / or coils may also be incorporated into the design of the stent or delivery system to achieve the same results.

[0110] It will be understood that this disclosure is, in many respects, merely illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps, without exceeding the scope of the present disclosure. This may include, to the extent appropriate, the use of any of the features of one illustrative embodiment in another embodiment. The scope of the present disclosure will, of course, be defined in the language in which the appended claims are expressed.

Claims

1. 1. An expandable medical device, comprising: a tubular support structure including an inner surface, an outer surface, a proximal end region, a distal end region, a lumen extending from the proximal end region to the distal end region, and a portion of the tubular support structure defining a retention member extending radially away from the outer surface, the retention member having a distal-facing surface and a proximal-facing surface; a membrane disposed within the lumen of the tubular support structure; the membrane is secured to the inner surface of the tubular support structure at a first circumferential attachment region, and the membrane is secured to the inner surface of the tubular support structure at a second circumferential attachment region; the membrane is not attached to the inner surface of the tubular support structure between the first circumferential attachment region and the second circumferential attachment region, defining a tissue ingrowth region between the inner surface of the tubular support structure and the outward-facing surface of the membrane.

2. The medical device of claim 1 , wherein the membrane is configured to maintain a passageway.

3. 3. The medical device of claim 1 or 2, wherein the tissue ingrowth region extends circumferentially around the inner surface of the tubular support structure.

4. The medical device of claim 1 , wherein the membrane is formed from an elastic material.

5. 4. The medical device of claim 1, wherein the membrane is designed to allow tissue ingrowth between the inner surface of the tubular support structure and the outward-facing surface of the membrane.

6. 6. The medical device of claim 1, wherein the first circumferential attachment region is secured to the inner surface of the tubular support structure along the distal end region, and the second circumferential attachment region is secured to the inner surface of the tubular support structure at a location distal to the retention member.

7. 7. The medical device of claim 1, wherein the tubular support structure includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and the membrane spans the plurality of gaps in the portion of the tubular support structure that defines the retention member.

8. 8. The medical device of claim 7, wherein the tubular support structure includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and the membrane encloses the plurality of gaps in the portion of the tubular support structure that defines the retention member.

9. 9. The medical device of claim 1, wherein the first circumferential attachment region is secured to the inner surface of the tubular support structure along the distal end region, and the second circumferential attachment region is secured to the inner surface of the tubular support structure at a location proximal to the retention member.

10. 10. The medical device of claim 1, wherein the tubular support structure includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and wherein tissue can grow through the plurality of gaps in a portion of the tubular support structure between the first circumferential attachment region and the second circumferential attachment region.

11. The medical device of claim 10 , wherein the distal end region of the tubular support structure further includes a flared portion.

12. 12. The medical device of claim 11, wherein the first circumferential attachment region is secured to the inner surface of the tubular support structure at a location proximal to the flared portion and the second circumferential attachment region is secured to the inner surface of the tubular support structure at a location distal to the retention member.

13. 13. The medical device of claim 1, wherein the membrane is in direct contact with the inner surface of the portion of the tubular support structure that defines the retention member.

14. 14. The medical device of claim 11, wherein the flaring portion includes a plurality of gaps extending from the outer surface of the tubular support structure to the inner surface of the tubular support structure, and the flaring portion is free of the membrane to allow tissue to grow along the flaring portion and through the plurality of gaps in the tubular support structure.

15. 15. The medical device of claim 11, wherein the retention member has a diameter and the flared portion has a diameter, the diameter of the retention member being greater than the diameter of the flared portion.

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