STENT WITH SELECTIVE MEMBRANE COATING

Medical devices and methods for using medical devices are disclosed. An example expandable medical device includes a tubular scaffold including an inner surface, an outer surface, a proximal end region, a distal end region, and a medial region extending between the proximal end region and the distal end region, wherein the tubular scaffold defines a folded-over portion, and wherein the folded-over portion extends from the distal end region toward the proximal end region. Further, the medical device includes a membrane disposed along the at least a portion of the medial region of the tubular scaffold.

TECHNICAL FIELD

The present disclosure pertains to medical devices, methods for manufacturing medical devices, and uses thereof. More particularly, the present disclosure pertains to stents having selective membrane coatings for implantation in body lumens, and associated methods.

BACKGROUND

Implantable medical devices (e.g., expandable stents) may be designed to treat a variety of medical conditions in the body. For example, some expandable stents may be designed to radially expand and support a body lumen and/or provide a fluid pathway for digested material, blood, or other fluid to flow therethrough following a medical procedure. Some medical devices may include radially or self-expanding stents which may be implanted transluminally via a variety of medical device delivery systems. These stents may be implanted in a variety of body lumens such as coronary or peripheral arteries, the esophageal tract, gastrointestinal tract (including the intestine, stomach and the colon), tracheobronchial tract, urinary tract, biliary tract, vascular system, etc.

In some instances it may be desirable to design stents to include sufficient flexibility while maintaining sufficient radial force to open the body lumen at the treatment site. However, in some stents, the compressible and flexible properties that assist in stent delivery may also cause a stent to migrate from its originally deployed position. For example, stents that are designed to be positioned in the gastrointestinal and/or biliary tract may migrate due to peristalsis (i.e., the involuntary constriction and relaxation of the muscles of the stomach, intestine, and colon). Further, the generally moist and inherently lubricious environment of the stomach, intestine, colon, etc. may contribute to a stent's tendency to migrate when deployed therein. Further yet, the relative motion of non-connected structures (e.g., the relative motion of a hepatic duct and the stomach) may contribute to a stent's tendency to migrate when deployed therein.

Various medical procedures involve the temporary or permanent joining of non-connected anatomical structures. Some examples include a hepaticogastrostomy (HGS), which involves joining a hepatic duct and the stomach to drain the bile duct, EUS-guided gallbladder drainage (EUS-GBD), utilized for the treatment of acute cholecystitis and symptomatic cholelithiasis in patients who are poor operative candidates, a gastrojejunal(GJ) bypass or gastrojejunostomy procedure to create an anastomosis between the small intestine and stomach wall, and stomas to create an artificial opening into the large intestine or other region of the digestive tract. In these medical procedures, peristalsis and gross organ movement in one or both of the anatomical structures being connected may create difficulties in using stents to join the structures due to stent migration. Accordingly procedures may require a stent to permit leak-free drainage from one anatomical structure (e.g., hepatic ducts) to another anatomical structure (e.g., stomach) while also permitting tissue ingrowth into the stent to prevent stent migration.

Therefore, it may be desirable to design a stent having both drainage capabilities and anti-migration features to reduce the stent's tendency to migrate. Examples of medical devices including both drainage and anti-migration features, and methods of using them are disclosed herein.

SUMMARY

This disclosure provides design, material, manufacturing method, and use alternatives for medical devices. An example expandable medical device includes a tubular scaffold including an inner surface, an outer surface, a proximal end region, a distal end region, and a medial region extending between the proximal end region and the distal end region, wherein the tubular scaffold defines a folded-over portion, and wherein the folded-over portion extends from the distal end region toward the proximal end region. Further, the medical device includes a membrane disposed along the at least a portion of the medial region of the tubular scaffold.

Alternatively or additionally to the embodiment above, wherein, wherein the folded-over portion extends away from the outer surface of the medial region toward the proximal end region at an acute angle.

Alternatively or additionally to the embodiment above, wherein the folded-over portion includes interstices extending from an outer surface of the folded-over portion to an inner surface of the folded-over portion, and wherein the interstices are configured to permit tissue to grow therein.

Alternatively or additionally to the embodiment above, wherein the folded-over portion extends circumferentially around a longitudinal axis of the tubular scaffold.

Alternatively or additionally to the embodiment above, wherein the folded-over portion is positioned substantially parallel to a central longitudinal axis of the stent.

Alternatively or additionally to the embodiment above, wherein the membrane extends along an inner surface of the medial region of the tubular scaffold from the distal end region to the proximal end region.

Alternatively or additionally to the embodiment above, wherein the membrane extends along a portion of an inner surface of the medial region of the tubular scaffold, and wherein a portion of the medial region is devoid of the membrane.

Alternatively or additionally to the embodiment above, wherein the portion of the medial region which is devoid of the membrane is positioned radially interior of to the folded-over portion.

Alternatively or additionally to the embodiment above, wherein the membrane is configured to maintain a passageway for fluid to flow therethrough.

Alternatively or additionally to the embodiment above, wherein the membrane is formed from an elastic material.

Alternatively or additionally to the embodiment above, wherein the medical device further comprises a retention member extending radially away from the outer surface at the proximal end region, wherein the retention member has a distally facing surface positioned substantially parallel to a proximally facing surface.

Alternatively or additionally to the embodiment above, wherein the tubular scaffold includes interstices extending from the outer surface of the tubular scaffold to the inner surface of the tubular scaffold, and wherein the membrane spans the interstices of the portion of the tubular scaffold which defines the retention member.

Alternatively or additionally to the embodiment above, wherein the membrane is in direct contact with the inner surface of the portion of the tubular scaffold defining the retention member.

Alternatively or additionally to the embodiment above, wherein the distal end region of the tubular scaffold further includes a flared portion.

Alternatively or additionally to the embodiment above, wherein the folded-over portion is spaced apart from and extends away from the outer surface of the flared portion at an acute angle.

Alternatively or additionally to the embodiment above, wherein the flared portion includes interstices extending from the outer surface of the tubular scaffold to the inner surface of the tubular scaffold, wherein the flared portion is devoid of the membrane such that tissue is permitted to grow through the interstices of the tubular scaffold along the flared portion.

Alternatively or additionally to the embodiment above, wherein the retention member has an outermost diameter, wherein the flared portion has an outermost diameter, wherein the folded-over portion has an outermost diameter, and wherein the outmost diameter of the retention member is greater than the outmost diameter of the flared portion, the folded-over portion or both the flared portion and the folded-over portion.

Another example expandable medical device includes a tubular scaffold including an inner surface, an outer surface, a proximal end region, a distal end region, and a medial region extending between the proximal end region and the distal end region, wherein the tubular scaffold defines an everted portion, and wherein the everted portion extends from the distal end region toward the proximal end region. The medical device also includes a membrane disposed along a first portion of the medial region of the tubular scaffold, wherein a second portion of the medial region of the tubular scaffold is devoid of the membrane, and wherein the second portion of the medial region of the tubular scaffold which is devoid of the membrane is positioned radially interior to the everted portion.

Alternatively or additionally to the embodiment above, wherein the everted portion extends away from the outer surface of the medial region at an acute angle.

Another expandable medical device includes a tubular scaffold including an inner surface, an outer surface, a proximal end region, a distal end region, and a medial region extending between the proximal end region and the distal end region, wherein the tubular scaffold defines a folded-over portion, and wherein the folded-over portion extends from the distal end region toward the proximal end region. The medical device also includes a membrane disposed along a first portion of the medial region of the tubular scaffold, wherein a second portion of the medial region of the tubular scaffold is devoid of the membrane, and wherein the second portion of the medial region of the tubular scaffold which is devoid of the membrane is positioned radially interior to and spaced apart from the folded-over portion. Further, the tubular scaffold further comprises a retention member extending radially away from the medial region, wherein the retention member is a double-walled flange having a distal wall positioned substantially parallel to and spaced apart from a proximal wall of the double-walled flange.

DETAILED DESCRIPTION

FIG.1illustrates various organs in the digestive tract, including the stomach102, duodenum104, liver106, hepatic duct108, gallbladder110, common bile duct112, and pancreas114.

Bile, which is produced in the liver106, flows through a series of hepatic ducts108that drain into one large duct called the common bile duct (CBD)112. The CBD then connects to the duodenum104, allowing the bile to flow into the duodenum for digestion. If the hepatic or bile ducts become blocked, bile cannot drain normally and backs up or builds up in the liver106. Blocked bile ducts and the resulting increase in bile pressure may cause abdominal pain, jaundice, dark urine, nausea and poor appetite, leading to potentially serious conditions.

Endoscopic retrograde cholangiopancreatography (ERCP) may be used to diagnose and treat conditions of the bile ducts, including, for example, gallstones, inflammatory strictures, leaks (e.g., from trauma, surgery, etc.), and cancer. Blockage of the biliary duct may occur in many of the disorders of the biliary system, including the disorders of the liver, such as, primary schlerosing cholangitis, stone formation, scarring in the duct, etc. Draining blocked fluids from the biliary system may be used to treat the disorders. Methods of biliary drainage include the placement of plastic or metal stents to relieve the blockage. In the case of a gallstone causing the obstruction in the duct, a number of products are also available to resolve this through ERCP. However, access to the bile ducts via ERCP may not be possible due to a variety of reasons such as a tumor blocking the passageway, anatomic variation, periampullary diverticula, post ampullary removal surgery (e.g., a Whipple procedure), etc. When ERCP methods prove unsuccessful, percutaneous drainage (PTCD) can be performed. However, PTCD may be associated with complications such as bleeding and bile leakage. If subsequent internal drainage cannot be achieved, the patient would have to accept long-term external biliary drainage, which can be uncomfortable and have significant impairment of quality of life.

Endoscopic Ultrasound (EUS) guided biliary drainage (BD) offers an alternative option to surgery and percutaneous drainage for treating obstructive jaundice when ERCP drainage fails. Hepaticogastrostomy (HGS) may be performed to join the hepatic duct108to the stomach102. This would allow the build-up of bile to flow into the stomach and may relieve the symptoms caused by bile buildup, i.e. jaundice. However, the hepatic duct108and the stomach102are spaced apart by a distance D indicated by the arrow5inFIG.1. The distance D between the organs may require a relatively long stent. Additionally, as the stomach muscles contract to churn food, the distance D between the gastric wall of the stomach102relative to the hepatic duct108varies, from a relatively small distance D when the stomach is relaxed as to a greater distance when the stomach is contracted. In addition to the gastric wall flexing, the stomach undergoes peristalsis during digestion. This relative motility of the stomach is understood to be complex, in three dimensions rather than in an exclusively linear manner. The distance between target organs to be joined, the relative movement of at least one of the organs, as well as the normal motion of the body (e.g., twisting, running, jumping, etc.) may increase the chance of stent migration.

FIG.2illustrates an example expandable medical device, namely a stent120(e.g., a drainage stent) including a first end region122(e.g., a proximal end region), a second end region124(e.g., distal end region) and a medial region126extending between the first end region122and the second end region124. The stent120may include one or more stent strut members142forming a tubular scaffold. Stent strut members142may extend helically, longitudinally, circumferentially, or otherwise along stent120. WhileFIG.2shows stent strut members142extending along the entire length of stent120, in other examples, the stent strut members142may extend only along a portion of stent120.

In some examples, the stent120may be a self-expanding stent. Self-expanding stent examples may include stents having an expandable scaffold. In some instances, the self-expanding stent may have one or more filaments142combined to form a rigid and/or semi-rigid tubular stent scaffold. For example, the stent filaments142of the stent120may include wires or filaments which are braided, wrapped, intertwined, interwoven, weaved, knitted, looped (e.g., bobbinet-style) or the like to form the tubular scaffold. For example, while the example stents disclosed herein may resemble a braided stent, this is not intended to limit the possible stent configurations. Rather, the stents depicted in the Figures may be stents that are braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) or the like to form the stent scaffold. In various embodiments, the woven, braided and/or knitted member(s) may include a single filament woven upon itself, or multiple filaments woven together. In various embodiments, any of the woven, braided and/or knitted member(s), which comprise the elongate tubular body, may include a variety of different cross-sectional shapes (e.g., oval, round, flat, square, etc.).

Alternatively, the stent120may be a monolithic structure formed from a cylindrical tubular member, such as a single, cylindrical tubular laser-cut Nitinol tubular member, in which the remaining portions of the tubular member form the tubular scaffold. Openings or interstices through the wall of the stent120may be defined between adjacent filaments142or struts of the tubular scaffold.

The stent120in the examples disclosed herein may be constructed from a variety of materials. For example, the stent120(e.g., self-expanding or balloon expandable) may be constructed from a metal (e.g., Nitinol, Elgiloy, etc.). In other instances, the stent120may be constructed from a polymeric material (e.g., PET). In yet other instances, the stent120may be constructed from a combination of metallic and polymeric materials. Additionally, stent120may include a bioabsorbable and/or biodegradable material.

Additionally, the stent120may be configured to shift between a first (e.g., constrained, collapsed, non-expanded) configuration and a second (e.g., non-constrained, expanded) configuration. In an expanded configuration, the first end region122of the stent120may include a retention member128defining a first opening130. The retention member128may be formed from the stent strut members142used to form other portions of the stent120. For example, the retention member128may be formed from the same stent strut members142used to form the medial region126.

FIG.2further illustrates that, in some examples, the medial region126may include a uniform outer diameter D3along its length. Additionally, the medial region126of the stent120may include a circumference and a longitudinal axis. The medial region126of the stent120may extend between the second end region124and the retention member128of the first end region122. The stent120may define an open interior lumen (e.g., passage, channel, etc.) extending from the first end region122to the second end region124.

The retention member128may extend radially away from (e.g., substantially perpendicular to) the longitudinal axis of the medial region126to define a first surface138aand a second surface138b. In some instances, the first surface138a, which may be a distally facing surface of the retention member128, is substantially parallel to the second surface138b, which may be a proximally facing surface of the retention member128. The first surface138amay be configured to atraumatically engage a (e.g., inner) tissue wall of a first body lumen (e.g., the stomach or duodenum).

FIG.2further illustrates that the second end region124of the stent120may be everted on itself to form a folded-over portion160. For example, it can be appreciated that to form the folded-over portion160, the stent scaffold may be wrapped, intertwined, interwoven, weaved, looped such that the individual filaments142extend continuously along the medial region126to the second end region124of the stent120whereby they curve and extend back (e.g., bend back) toward the first end region122of the stent120. In the folded-over configuration shown inFIG.2, the folded-over portion160includes a first outwardly-facing surface162. It can be appreciated that this first outwardly facing surface162may extend circumferentially around the longitudinal axis of the stent120. Additionally,FIG.2illustrates that the folded-over portion160may have a maximum outer diameter D2.

Further, the outwardly facing surface162of the folded-back portion160may be configured to atraumatically engage a (e.g., inner) tissue wall of an adjacent or apposed second body lumen (e.g., a biliary duct). In the example stent120illustrated inFIG.2, the outwardly facing surface162, the first surface138aand the second surface138bmay prevent or limit movement/migration of the deployed stent120within or between the first and second body lumens.

FIG.2further illustrates that, in some examples, an outer diameter D1of the retention member128may be greater than the outer diameter D2of the folded-over portion160. However, in other examples, the outer diameter D1of the retention member128may be equal to the outer diameter D2of the folded-over portion160. The medial region126may include a constant outer diameter D3extending between the second end region124and the retention member128, whereby the diameter D3of the medial region126is less than the diameters D1and D2of the retention member128and the folded-over portion160, respectively.

In some examples, the diameter D1may 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, the diameter D2may 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, the diameter D3may 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 15 mm to about 25 mm.

Additionally, in some examples, the first end region122of the stent120may include free ends146of the one or more woven, braided or knitted strut members142which are not connected, and instead form sharp or pointed free ends of the strut members142. As will be understood by those of skill in the art, the surface138aof the retention member128may atraumatically engage an inner tissue wall of a first body lumen such that the free ends146extend into the first body lumen and do not contact the tissue wall.

As discussed herein, for HGS patients, stent migration may cause serious complications including death. If there is no tissue ingrowth-based adhesion at various anatomical regions, a deployed stent may migrate proximally into the stomach, causing leakage of biliary contents into the peritoneum, resulting in peritonitis. If there is sufficient or excessive adhesion at the hepatic duct, the stent may migrate distally into the peritoneum, causing leakage of biliary and stomach contents into the peritoneum, also causing peritonitis. Additionally, a migrated stent is free to abrade the outer gastric wall and other organs or vessels in the vicinity. Anatomically, stent migration can occur as a result of the hepatic duct being a generally static vessel, whereas the stomach is a highly motile vessel, as discussed herein. Accordingly, one method to reduce stent migration may include exposing bare metal portions of the stent to the tissue of the body lumen. The stent scaffold may then provide a structure that promotes tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The tissue ingrowth may anchor the stent in place and reduce the risk of stent migration.

FIG.2illustrates that, in some examples, the tubular scaffold of the stent120may include one or more non-covered (e.g., bare) portions designed to promote tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The non-covered portions may be devoid of a membrane, coating or other covering and thus the interstices of the tubular scaffold in the non-covered portions are open to tissue ingrowth. For example,FIG.2illustrates that the stent120may include the non-covered portion134. It can be appreciated that, in some examples, the non-covered portion134of the tubular scaffold of the stent120may include the folded-over portion160of the stent120. In other words, the folded-over portion160of the stent120shown inFIG.2may be bare (e.g., devoid or free of a membrane, coating, etc.) allowing tissue ingrowth through the interstices of the tubular scaffold along the folded-over portion160. Further, as will be discussed in greater detail with respect toFIG.3, the non-covered portion134of the tubular scaffold of the stent120may include a portion of the medial region126of the stent120proximate the folded-over portion160. It can be appreciated that when positioned in a body lumen, the outer-facing surface162of the folded-over portion160, which may be a non-covered or bare portion of the stent120, may contact the vessel wall.

Additionally,FIG.2illustrates that the stent120may include a membrane150(e.g., coating, membrane coating, etc.) extending along the tubular scaffold of the stent120, such as within the lumen of the tubular scaffold of the stent120. For example,FIG.2illustrates that the membrane150may extend along a length L1of the tubular scaffold of the stent120. The length L1along which the membrane150extends within the lumen of the tubular scaffold of the stent120may include a portion of the medial region126and the first end region122(including the retention member128). As will be discussed in greater detail below, the membrane150may extend along an inner surface and/or outer surface of the filaments142forming the medial region126in order to span across the interstices of the medial region126, whereby the membrane150defines a leak-free, passageway (e.g., channel, lumen, tunnel, etc.) which may permit drainage of bodily substances (e.g., bile) from one anatomical organ (e.g., liver) to another anatomical organ (e.g., stomach). In some examples, the membrane150may be an elastomeric or non-elastomeric material. For example, the membrane150may be a polymeric material, such as silicone, polyurethane, UE, PVDF, PTFE, ePTFE, ChronoFlex® or similar biocompatible polymeric formulations.

FIG.3illustrates a cross-sectional view of the stent120taken along line3-3ofFIG.2.FIG.3illustrates the first end region122, the second end region124and the medial region126. The stent120may be formed from one or more braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) filaments142to form the tubular scaffold of the stent120.FIG.3also illustrates the folded-over portion160positioned along the second end region124. The folded-over portion160may include the first outer facing surface162described herein.FIG.3further illustrates that the folded-over portion160may also include a second inward facing surface164. The inward facing surface164may be defined as the surface of the folded-over portion160which faces toward the longitudinal axis of the stent120, and thus faces toward the medial region126of the stent120. Additionally, the stent may include a retention member128positioned along the first end region122.

FIG.3further illustrates the folded-over portion160extending away from an outer surface of the medial region126at an angle θ. In some instances, the angle θ may be about 20 degrees or more, 30 degrees or more, 45 degrees or more, 60 degrees or more, or 70 degrees or more. The folded-over portion160may taper radially outward as the folded-over portion160extends toward the first end region122of the stent120. Thus, the folded-over portion160may taper radially outward as the folded-over portion160extends over and surrounds a portion of the medial region126. Further,FIG.3illustrates the folded-over portion160extending along the longitudinal axis of the stent120for a length L2. It can be appreciated that the stent120may include embodiments in which the folded-over portion160extends away from the outer surface of the medial region126at a variety of different angles θ. Further, it can be appreciated that the stent120may include embodiments in which the folded-over portion160extends along the medial region126at a variety of different lengths.

FIG.3further illustrates the membrane150extending along a portion of the inner surface of the filaments142defining the tubular scaffold of the stent120. In other words,FIG.3illustrates that the stent120may include the membrane150extending within the inner lumen of the tubular scaffold of the stent120. In other instances, the membrane150may extend along a portion of the outer surface of the filaments142defining the tubular scaffold of the stent120. As discussed herein,FIG.3illustrates the membrane extending along a length L1of the medial region126of the stent120, occluding the interstices between the filaments142along the medial region126.

As discussed herein, the first outer-facing surface162and the second inner-facing surface164of the folded-over portion160may be devoid of the membrane150, thereby permitting tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. Additionally,FIG.3illustrates that a portion134of the medial region126may be devoid of the membrane150, thereby permitting tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The non-covered portion134may extend from the covered portion of the medial region126to the folded-over portion160. The entire non-covered portion134may be devoid of the membrane150, coating or other covering and thus the interstices of the tubular scaffold in the non-covered portion134may be open to tissue ingrowth.

It can be appreciated that as the proportion of the stent120which includes a membrane150increases, the proportion of the stent120which does not include a membrane decreases, and vice versa. In some examples, the ratio of the covered portion L1to the non-covered portion134may be about 9:1 of the covered portion L1to the uncovered portion134, or about 4:1 of the covered portion L1to the uncovered portion134, or about 7:3 of the covered portion L1to the uncovered portion134, or about 3:2 of the covered portion L1to the uncovered portion134, or about 1:1 of the covered portion L1to the uncovered portion134. The uncovered portion134may be designed to be more flexible than the covered portion L1, allowing for better response when positioned in highly motile regions of the body.

Further, it can be appreciated that designing the stent120to include a relatively greater length of the uncovered portion134to the covered portion L1may dedicate a greater percentage of the overall stent length to bare region duct drainage and anti-migration features. However, while longer uncovered portions134may allow for higher potential for side branch drainage and anti-migration ingrowth, the reduction in the covered portion L1may reduce the effective length of the stent120that can be bridged between disconnected anatomical vessels (e.g., the distance between the gastric wall into the liver parenchyma). The uncovered portion134and the length L2of the folded-over portion160must be sized to allow enough resistance to stent migration (so as to prevent migration initially through mechanical resistance and eventually with the addition of tissue ingrowth) while also allowing the stent120to include enough of a covered portion L1to bridge the distance between disconnected anatomical vessels (e.g., the distance between the gastric wall into the liver parenchyma).

It can be appreciated that tissue may be permitted to grow around, between, through, within, etc. those strut members142of the tubular scaffold of the stent120in which the membrane150is not attached. In other words,FIG.3illustrates multiple “tissue ingrowth regions” defined along both the folded-over portion160and along the non-covered portion134along the medial region126of the tubular scaffold of the stent120. The uncovered or bare portions of the tubular scaffold of the stent120may provide structures that promote tissue ingrowth to anchor the stent120in place and reduce the risk of stent migration. Further, it can be appreciated that the membrane150may define a leak-free, passageway (e.g., channel, lumen, tunnel, etc.) which may permit drainage of bodily substances (e.g., bile) from one anatomical organ (e.g., liver) to another anatomical organ (e.g., stomach).

When positioned in the body (e.g.,FIG.10illustrates the stent120positioned in a hepatic duct116of the liver106), the outer facing surface162of the folded-over portion160may directly contact the vessel wall. Accordingly, the non-covered filaments142forming the folded-over portion160may promote an initial (primary) tissue ingrowth region to anchor the stent120in place and reduce the risk of stent migration. In other words, after the initial placement of the stent120in the body lumen, the interstices formed from the filaments142of the folded-over portion160may provided openings through which tissue ingrowth may occur. This may be the primary mechanism for which the distal end region124of the stent120may be anchored to the duct.

However, it can be appreciated that the non-covered portion134may also provide a secondary tissue ingrowth region to anchor the stent120in place and reduce the risk of stent migration. For example, tissue may initially grow within the folded-over portion160, during which time the non-covered portion134may remain bare, thereby allowing fluid drainage therethrough into membrane150covered portion of the medial region126. However, over time, tissue may grow into the interstices of the non-covered portion134, thereby providing a secondary anchoring tissue ingrowth region. As tissue ingrowth occurs within the non-covered portion134, the ability for fluid drainage to occur within the non-covered portion134may decrease.

It can be further appreciated that the folded-over portion160may provide a radially outward force on the vessel wall within which the stent120is positioned. In other words, the folded-over portion may include a spring force which forces the outer facing surface162of the folded-over portion160to oppose the tissue of the vessel wall. Further, this radially outward spring force also acts to create a space between the inner facing surface164of the folded-over portion160and the outer surface of the non-covered portion134of the medial region126. It can be appreciated that this design may create a double braided layer of bare, non-covered filaments (e.g., one layer of the folded-over portion160positioned radially outward of a second layer, which is the bare non-covered portion134of the medial region126).

It can further be appreciated that the relative amount of non-covered (e.g., bare) portions of the stent120versus the membrane150covered portions may be customized (e.g., tailored) based on the where in the body the stent120may be positioned. For example, tissue ingrowth may be relatively fast in some organs (e.g., the hepatic duct) and, therefore, it may be desirable to design the stent120to have a shorter folded-over portion160(e.g., a shorter length L2of the outer facing surface162inFIG.3) for primary tissue ingrowth and anchorage. It can be appreciated that designing the stent120to include a shorter length L2of the outer facing surface162of the folded over region160may permit more of the non-covered portion134to drain fluid from side-branches of the organ in which the stent120is positioned.

Additionally, tissue ingrowth may be relatively slow in some organs (e.g., the pancreas) and, therefore, it may be desirable to design the stent120to have a longer folded-over portion160(e.g., a longer length L2of the outer facing surface162inFIG.3) for primary tissue ingrowth and anchorage. It can be appreciated that designing the stent120to include a longer length L2of the outer facing surface162of the folded-over region160may result in more tissue ingrowth along the outer facing surface162of the folded-over portion160to help anchor the stent120in place while continuing to provide side-branch drainage.

One advantage of the stent designs described herein which include a folded-over portion and a non-covered medial portion is that the non-covered medial portion (e.g., portion134inFIG.3) and the folded-over portion (e.g., folded-over portion160inFIG.3) allow for side branch drainage and tissue ingrowth, respectively, to be achieved independent of one another with the promotion of tissue ingrowth to have less impact on the prolonged drainage of side branch vessels. This design is combined with the membrane150which may define a leak-free, passageway (e.g., channel, lumen, tunnel, etc.) which may permit drainage of bodily substances (e.g., bile) from one anatomical organ (e.g., liver) to another anatomical organ (e.g., stomach).

It can be further appreciated that the relative lengths of the non-covered portion134and the covered portion L1may differ from that illustrated inFIG.3. For example,FIG.4illustrates a cross-sectional view of the stent120identical toFIG.3except that more of the stent120may include a membrane150.FIG.4illustrates the membrane150extending along substantially the entire length of the medial region126to the second end region124(e.g.,FIG.4illustrates the entire length of the medial region126may include the membrane150). The portion of the medial region126which includes the membrane is identified as length L3inFIG.4. However,FIG.4further illustrates that the membrane150may extend along the medial region126to the point at with the stent scaffold folds over upon itself (e.g., the point at which the stent struts are everted to form the folded-over portion160). WhileFIG.4illustrates the membrane150lengthening from length L1(shown inFIG.3) to length L3(shown inFIG.4), the folded-over portion160may remain devoid of the membrane150.

For example,FIG.5illustrates an alternative embodiment of the stent120whereby the folded-over portion160has been everted approximately 180 degrees such that the outer facing surface162and the inner facing surface164may be substantially parallel to the longitudinal axis of the stent120. Additionally,FIG.5illustrates the folded-over portion160extending along the medial region126of the stent120a length L4.FIG.5further illustrates the membrane150extending along the inner surface of the filaments142a distance L5. Comparing the example stent embodiment of shown inFIG.4to that shown inFIG.5illustrates that the stent embodiment shown inFIG.5may include a relatively greater percentage of non-covered stent filaments142and relatively lower percentage of a membrane150covered stent scaffold. In some instances, the folded-over portion160may extend along and surround substantially the entire length of the uncovered portion of the medial region126.

FIG.6illustrates an example expandable medical device, namely a stent220(e.g., drainage stent). The stent220may be similar in form and function to the stent120described with respect toFIG.2. For example, the stent220may include a first end region222(e.g., a proximal end region), a second end region224(e.g., distal end region) and a medial region226extending between the first end region222and the second end region224. The stent220may include one or more stent filaments242forming a tubular scaffold. Stent filaments242may extend helically, longitudinally, circumferentially, or otherwise along stent220. WhileFIG.6shows stent filaments242extending along the entire length of stent220, in other examples, the stent filaments242may extend only along a portion of stent220.

In some examples, the stent220may be a self-expanding stent. Self-expanding stent examples may include stents having an expandable scaffold. In some instances, the self-expanding stent may have one or more filaments242combined to form a rigid and/or semi-rigid tubular stent scaffold. For example, the filaments242of the stent220may include wires or filaments which are braided, wrapped, intertwined, interwoven, weaved, knitted, looped (e.g., bobbinet-style) or the like to form the tubular scaffold. For example, while the example stents disclosed herein may resemble a braided stent, this is not intended to limit the possible stent configurations. Rather, the stents depicted in the Figures may be stents that are braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) or the like to form the stent scaffold. In various embodiments, the woven, braided and/or knitted member(s) may include a single filament woven upon itself, or multiple filaments woven together. In various embodiments, any of the woven, braided and/or knitted member(s), which comprise the elongate tubular body, may include a variety of different cross-sectional shapes (e.g., oval, round, flat, square, etc.).

Alternatively, the stent220may be a monolithic structure formed from a cylindrical tubular member, such as a single, cylindrical tubular laser-cut Nitinol tubular member, in which the remaining portions of the tubular member form the tubular scaffold of the stent220. Openings or interstices through the wall of the stent220may be defined between adjacent filaments242or strut members.

The stent220in the examples disclosed herein may be constructed from a variety of materials. For example, the stent220(e.g., self-expanding or balloon expandable) may be constructed from a metal (e.g., Nitinol, Elgiloy, etc.). In other instances, the stent220may be constructed from a polymeric material (e.g., PET). In yet other instances, the stent220may be constructed from a combination of metallic and polymeric materials. Additionally, stent220may include a bioabsorbable and/or biodegradable material.

Additionally, the stent220may be configured to shift between a first (e.g., constrained, collapsed, non-expanded) configuration and a second (e.g., non-constrained, expanded) configuration. In an expanded configuration, the first end region222of the stent220may include a retention member228defining a first opening230. The retention member228may be formed from the stent filaments242used to form other portions of the stent220. For example, the retention member228may be formed from the same stent filaments242used to form the medial region226.

FIG.6further illustrates that, in an expanded configuration, the second end region224of the stent220may include a flared portion232having a second opening236. Additionally, similar to that described with respect to the stent120ofFIG.2, the second end region224of the stent220may be everted on itself to form a folded-over portion260. For example, it can be appreciated that to form the folded-over portion260, the stent scaffold may be wrapped, intertwined, interwoven, weaved, looped such that the individual filaments242extend continuously along the medial region226to the second end region224of the stent220, whereby they curve and extend back (e.g., bend back) toward the first end region222of the stent220. It can be appreciated that prior to being bent back over on themselves, the individual filaments242which form the folded-over portion260may have an inner surface which faces the longitudinal axis of the stent220. However, in the folded-over configuration, the inner facing surface of the filaments242(which form the folded-over portion260) have been everted and subsequently face outward away from the longitudinal axis of the stent220. This first outwardly facing surface of filaments242is identified by reference numeral262inFIG.6. It can be appreciated that this first outwardly facing surface262may extend circumferentially around the longitudinal axis of the stent220. Additionally,FIG.6illustrates that the folded-over portion260may have a maximum outer diameter D6.

Additionally, the medial region226of the stent220may include a circumference and a longitudinal axis. The medial region226of the stent220may extend between the flared portion232of the second end region224and the retention member228of the first end region222. The stent220may define an open interior lumen (e.g., passage, channel, etc.) extending from the first end region222to the second end region224.

The retention member228may extend radially away from (e.g., substantially perpendicular to) the longitudinal axis of the medial region226to define a first surface238aand a second surface238b. In some instances, the first surface238a, which may be a distally facing surface of the retention member228, is substantially parallel to the second surface238b, which may be a proximally facing surface of the retention member228. The first surface238amay be configured to atraumatically engage a (e.g., inner) tissue wall of a first body lumen (e.g., the stomach or duodenum). Further, as will be discussed in greater detail herein, the flared portion232(e.g., flared flange structure) of the second end region224may include an outer surface240, a portion of which may be configured to atraumatically engage a (e.g., inner) tissue wall of an adjacent or apposed second body lumen (e.g., a biliary duct). In the example stent220illustrated inFIG.6, the surfaces262,238a,240may prevent or limit movement/migration of the deployed stent220within or between the first and second body lumens.

FIG.6illustrates that, in some examples, an outer diameter D4of the retention member228may be greater than the outer diameter D5of the flared portion232and the outer diameter D6of the folded-over portion260. However, in other examples, the outer diameter D4of the retention member228may be equal to the outer diameter D5of the flared portion232and/or equal to the outer diameter D6of the folded-over portion260. In yet other examples, the outer diameter D4of the retention member228may be less than the outer diameter D5of the flared portion232and/or less than the outer diameter D6of the folded-over portion260. The medial region226may include a constant outer diameter D7extending between the flared portion232and the retention member228, whereby the diameter D7of the medial region226is less than the diameters D4, D5and D6of the retention member228, the flared portion232, and the folded-over portion260, respectively. As discussed herein, in some examples the outer diameter D7of the medial region226may be substantially equal to the outer diameter D5of the flared portion232.

In some examples, the diameter D4may 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, the diameter D5may 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, the diameter D6may 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, the diameter D7may 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.

Additionally, in some examples, the first end region222of the stent220may include free ends246of the one or more woven, braided or knitted strut members242which are not connected, and instead form sharp or pointed free ends of the strut members242. As will be understood by those of skill in the art, the surface238aof the retention member228may atraumatically engage an inner tissue wall of a first body lumen such that the free ends246extend into the first body lumen and do not contact the tissue wall.

As discussed herein, for HGS patients, stent migration may cause serious complications including death. If there is no tissue ingrowth-based adhesion at various anatomical regions, a deployed stent may migrate proximally into the stomach, causing leakage of biliary contents into the peritoneum, resulting in peritonitis. If there is sufficient or excessive adhesion at the hepatic duct, the stent may migrate distally into the peritoneum, causing leakage of biliary and stomach contents into the peritoneum, also causing peritonitis. Additionally, a migrated stent is free to abrade the outer gastric wall and other organs or vessels in the vicinity. Anatomically, stent migration can occur as a result of the hepatic duct being a generally static vessel, whereas the stomach is a highly motile vessel, as discussed herein. Accordingly, one method to reduce stent migration may include exposing bare metal portions of the stent to the tissue of the body lumen. The stent scaffold may then provide a structure that promotes tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The tissue ingrowth may anchor the stent in place and reduce the risk of stent migration.

FIG.6illustrates that, in some examples, the tubular scaffold of the stent220may include one or more non-covered (e.g., bare) portions designed to promote tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The non-covered portions may be devoid of a membrane, coating or other covering and thus the interstices of the tubular scaffold in the non-covered portions are open to tissue ingrowth. For example,FIG.6illustrates that the stent220may include the non-covered portion234. It can be appreciated that, in some examples, the non-covered portion234of the tubular scaffold of the stent220may include the flared portion232and the folded-over portion260of the stent120. In other words, the flared portion232and the folded-over portion260of the stent220shown inFIG.6may be bare (e.g., devoid or free of a membrane, coating, etc.) allowing tissue ingrowth through the interstices of the tubular scaffold along the flared portion232.

Additionally,FIG.6illustrates that the stent220may include a membrane250(e.g., coating, membrane coating, etc.) extending along the tubular scaffold of the stent220, such as within the lumen of the tubular scaffold of the stent220. For example,FIG.6illustrates that the membrane250may extend along a length L6of the tubular scaffold of the stent220. The length L6along which the membrane250extends within the lumen of the tubular scaffold of the stent220may include a portion of the medial region226and the first end region222(including the retention member228). The membrane250may extend along inner surface and/or outer surface of the filaments142forming the medial region226in order to span across the interstices of the medial region226, whereby the membrane250defines a leak-free, passageway (e.g., channel, lumen, tunnel, etc.) which may permit drainage of bodily substances (e.g., bile) from one anatomical organ (e.g., liver) to another anatomical organ (e.g., stomach). In some examples, the membrane250be an elastomeric or non-elastomeric material. For example, the membrane250may be a polymeric material, such as silicone, polyurethane, UE, PVDF, PTFE, ePTFE, ChronoFlex® or similar biocompatible polymeric formulations.

It can be further appreciated that the stent220may be designed to include regions which do not include the membrane250and regions which include the membrane250in different configurations than that illustrated inFIG.6. In other words, the length of the non-covered portion234and the covered portion L6may differ from that illustrated inFIG.6. For example, the non-covered portion234may be longer than that shown inFIG.6(e.g., the non-covered portion may extend to a portion or all of the medial region226). In other examples, more of the stent220may include a membrane250. This would correspond to a lengthening of the length L6, whereby the membrane250may extend onto the flared portion232. It can be appreciated that as the proportion of the stent220which includes a membrane250increases, the proportion of the stent220which does not include a membrane decreases, and vice versa.FIG.7illustrates a cross-sectional view of the stent220taken along line7-7ofFIG.6.

FIG.7illustrates the first end region222, the second end region224and the medial region226. The stent220may be formed from one or more braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) filaments242to form the tubular scaffold of the stent220.FIG.7also illustrates the flared portion232and the folded-over portion260positioned along the second end region224. The folded-over portion260may include the first outer facing surface262described herein.FIG.7further illustrates that the folded-over portion260may also include a second inward facing surface264. The inward facing surface264may be defined as the surface of the folded-over portion260which faces toward the flared portion232and the longitudinal axis of the stent220. Additionally, the stent220may include a retention member228positioned along the first end region222.

FIG.7further illustrates the membrane250extending along a portion of the inner surface of the filaments242defining the tubular scaffold of the stent220. In other words, FIG.7illustrates that the stent220may include the membrane250extending within the inner lumen of the tubular scaffold of the stent220. In other instances, the membrane250may extend along a portion of the outer surface of the filaments142defining the tubular scaffold of the stent220. As discussed herein,FIG.7illustrates the membrane extending along a length L6of the medial region226of the stent220. Further,FIG.7illustrates the non-covered portion234(including the folded-over portion260). As discussed herein, the first outer-facing surface262and the second inner-facing surface264of the folded-over portion260may be devoid of the membrane250, thereby permitting tissue ingrowth (e.g., a hyperplastic response) into the interstices or openings thereof. The entire non-covered portion234may be devoid of the membrane250, coating or other covering and thus the interstices of the tubular scaffold in the non-covered portion234may be open to tissue ingrowth.

In some examples, the ratio of the covered portion L6to the non-covered portion may be about 9:1 of the covered portion L6to the uncovered portion234, or about 4:1 of the covered portion L to the uncovered portion234, or about 7:3 of the covered portion L6to the uncovered portion234, or about 3:2 of the covered portion L6to the uncovered portion234, or about 1:1 of the covered portion L6to the uncovered portion234. The uncovered portion234may be designed to be more flexible than the uncovered portion234, allowing for better response when positioned in highly motile regions of the body. It can be appreciated that designing the stent220to include a relatively greater length of the uncovered portion234to the covered portion L6may dedicate a greater percentage of the overall stent length to bare region duct drainage and anti-migration features. However, while longer uncovered portions234may allow for higher potential for side branch drainage and anti-migration ingrowth, the reduction in the covered portion L6may reduce the effective length of the stent220that can be bridged between disconnected anatomical vessels (e.g., the distance between the gastric wall into the liver parenchyma). The uncovered portion234of the stent220must be sized to allow enough resistance to stent migration (so as to prevent migration initially through mechanical resistance and eventually with the addition of tissue ingrowth) while also allowing the stent220to include enough of a covered portion L6to bridge the distance between disconnected anatomical vessels (e.g., the distance between the gastric wall into the liver parenchyma). Like the discussion set forth herein with respect toFIGS.2-3, it can be appreciated that the stent220shown inFIG.6may be customized based on the where in the body the stent220may be positioned. For example, based on the rate of tissue ingrowth and/or side branch fluid flow within a particular organ (e.g., pancreas, hepatic duct, etc.), it may be desirable to design the stent220to have a shorter or longer fold-over portion260and/or more or less of the medial region226and/or the flared portion232to be covered by the membrane250.

FIGS.8-9illustrate example stents that may be similar in form and function to the stents120,220described above. For example, each of the stents shown inFIGS.8-9may include a membrane disposed along the tubular scaffold of the stent, such as within the lumen of the tubular scaffold of the stent (e.g., as described with respect toFIG.2andFIG.6). The stents illustrated inFIGS.8-9may include various portions of the tubular scaffold of the stent which are uncovered to promote tissue ingrowth therethrough.

FIG.8illustrates a cross-sectional view of an example expandable medical device, namely a stent320. The example stent320may be similar in form and function to other stents described herein. For example, the stent320may include a first end region322, a second end region324and a medial region226extending therebetween. The stent320may be formed from one or more braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) filaments342to form the tubular scaffold of the stent320. The stent320may also include a folded-over portion360positioned along the second end region324.

Additionally, the stent320may include a retention member328positioned along the first end region322. The retention member328may extend radially away from (e.g., substantially perpendicular to) the longitudinal axis of the medial region326to define a first surface338aand a second surface338b. In some instances, the first surface338a, which may be a distally facing surface of the retention member328, is substantially parallel to the second surface338b, which may be a proximally facing surface of the retention member328. The first surface338amay be configured to atraumatically engage a (e.g., inner) tissue wall of a first body lumen (e.g., the stomach or duodenum).

FIG.8further illustrates that the stent320may include a membrane350extending along a portion of the inner surface of the strut members342defining the tubular scaffold of the stent320. In other words,FIG.8illustrates that the stent320may include a membrane350extending along a length L7within the inner lumen of the tubular scaffold of the stent320, whereby the membrane350may be attached along the inner surface of the tubular scaffold of the stent320.

FIG.8further illustrates that the folded-over portion360may include a substantially flat distal-facing surface366located at a distal extent of the stent320. In some instances, the flat distal-facing surface366may line in a plane generally perpendicular to the central longitudinal axis of the stent320. Additionally, similar to that described with respect to the stents120,220, the folded-over portion360may further include an outer facing surface362and an inner facing surface364. Additionally, like the stent embodiment shown inFIG.5, the outer facing surface362and the inner facing surface364of the folded-over portion360may be substantially parallel to the central longitudinal axis of the stent320. In some examples, it can be appreciated that the outer facing surface362may extend circumferentially around the longitudinal axis of the stent220and, together with the distal facing surface366, may define a substantially cylindrical shape.FIG.8illustrates that the folded-over portion360may extend toward the proximal end region322from the distal-facing surface366a length L8. The folded-over portion360may extend over and surround a portion of the medial region326of the stent320with the inner facing surfaced364spaced apart from the outer surface of the medial region326to define an annular gap therebetween. The folded-over portion360, as well as the portion of the medial region326in which the folded-over portion360surrounds, may be devoid of a membrane or covering (e.g., bare), retaining interstices of the tubular scaffold open for tissue ingrowth and/or fluid drainage therethrough.

FIG.9illustrates a cross-sectional view of an example expandable medical device, namely a stent420.FIG.9illustrates an alternative shape for the folded-over portion460along the distal end region424of an example drainage stent420. Similar to other stent designs described herein, the stent420may be formed from one or more braided, knitted, wrapped, intertwined, interwoven, weaved, looped (e.g., bobbinet-style) strut members442to form the tubular scaffold and folded-over portion460of the stent420.

FIG.9illustrates that the folded-over portion460may include one or more lobes468a,468b,468c,468dextending away from a central longitudinal axis472of the stent420.FIG.9further illustrates that the folded-over portion460may also include one or more valleys470a,470b,470c,470dformed between two lobes468a,468b,468c,468d. It can be appreciated that the outer diameter (as measured from the central longitudinal axis472) of the valleys470a,470b,470c,470dmay be less than the outer diameter of the lobes468a,468b,468c,468d.

FIG.9further illustrates that the one or more lobes468a,468b,468c,468dmay be spaced substantially equidistant around the central longitudinal axis472of the stent420. Thus, the folded-over portion460may have an undulating outer and/or inner surface forming the lobes468a,468b,468c,468dand the valleys470a,470b,470c,470d. It can be appreciated that one advantage of the shape of the folded-over portion460(including the alternating lobes468a,468b,468c,468dand valleys470a,470b,470c,470d) is that the larger outer diameter of the lobes468a,468b,468c,468dmay engage the tissue initially to provide early ingrowth opportunities while the smaller outer diameters of the valleys470a,470b,470c,470d, which would initially be spaced away from the tissue wall, maintain patency for continued drainage. Further, the lobed configured of the folded-over portion460may be incorporated into the folded-over portion of any of the other stents disclosed herein, including stents120,220,320.

As discussed herein, the examples of stents described herein may be designed to permit leak-free drainage from one anatomical structure (e.g., hepatic ducts) to another anatomical structure (e.g., stomach) while also permitting tissue ingrowth into the stent to prevent stent migration. For example,FIG.10illustrates the folded-over portion160of the example stent120positioned in a hepatic duct116of the liver106.FIG.10also illustrates the retention member128positioned in the stomach102with a laterally extending surface of the retention member128juxtaposed with the wall of the stomach102.

As discussed herein, the uncovered portions of the stent120may encourage tissue ingrowth, which can be desirable in order to prevent migration of stent120after it has been appropriately positioned within the body. For example, configuration of the example stents disclosed herein may allow for resistance to migration based on the selective allowance of tissue ingrowth along uncovered portions of the stent. For example, the atraumatic surface138(shown contacting the inner wall118of the stomach102) of the retention member128and also the surface along the outer facing surface162of the stent120may allow for resistance to migration based on the selective allowance of tissue ingrowth along those portions. As described herein, other stent designs disclosed herein may include additional regions for the allowance of tissue ingrowth. Additionally,FIG.10illustrates that the stent120may permit the flow of bile (or other body fluid) from the haptic duct116to the stomach102via the lumen of the stent120covered by the membrane150. Furthermore, fluid drainage may be permitted through the interstices of the uncovered medial region of the stent120into the lumen of the stent120.

The example stents shown inFIGS.2-9may contemplate braided stent designs which are utilized to permit leak-free drainage from one anatomical structure (e.g., hepatic ducts) to another anatomical structure (e.g., stomach) while also permitting tissue ingrowth into the stent to prevent stent migration. Additional stent designs are contemplated to permit leak-free drainage from one anatomical structure (e.g., hepatic ducts) to another anatomical structure (e.g., stomach) while also permitting tissue ingrowth into the stent to prevent stent migration. For example, knitted stents described herein may be utilized for the same purposes as the stents described inFIGS.2-9.

It can be appreciated that for any of the example stent configurations described herein, coating and/or encapsulating a greater proportion of the stent strut members may result in a less flexibility stent design. In other words, the example stents disclosed herein illustrate stent designs having different proportions (e.g., ratios) of uncovered (e.g., bare) verses covered (e.g., with a membrane, coating, etc.) stent strut members. It can be appreciated that these designs may vary in flexibility, with the stents having a lower percentage of covered stent strut members being more flexible.

Further, any of the stent designs described herein may include a variety of different braid patterns, some of which may be relatively more or less “dense” than other braid patterns. For example, any of the stent designs described herein may include braid patterns with different wire counts, wire thicknesses or braid patterns. Example braid patterns may include a standard 2-over-2 configuration or a standard 1-over-1 configuration. Different braid patterns may result in different braid pattern density, stent flexibility, stent foreshortening characteristics, etc. It can be appreciated that different braid patterns may be utilized to implement different balances between tissue ingrowth into the interstices of the stent and/or drainage within the non-covered portions of the stent.

It can be appreciated that, in addition to the HGS procedure described herein, the example stents described herein may be used in other medical procedures. For example, the stent designs described herein may 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 of the stent into a distal portion of the small intestine. The stent creates an anastomosis between the small intestine and the stomach, effectively rerouting the stomach contents directly into the small intestine. As both the stomach wall and intestine experience peristaltic motion, this would be considered a highly motile application, which may benefit from the stent, where the bypass can be achieved while allowing an adaptable channel which retains its diameter throughout peristalsis.

U.S. Provisional Patent Application No. 63/246,376, filed Sep. 21, 2021, U.S. patent application Ser. No. 17/941,867, filed Sep. 9, 2022, and U.S. Provisional Patent Application No. 63/427,618, filed Nov. 23, 2022, are herein incorporated by reference in their entirety for any and all purposes. These applications describe stents for implantation in body lumens and associated methods.

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

In at least some embodiments, portions or all of the stents or delivery systems may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are generally understood to be materials which are opaque to RF energy in the wavelength range spanning x-ray to gamma-ray (at thicknesses of <0.005 inches (0.127 mm)). These materials are capable of producing a relatively dark image on a fluoroscopy screen relative to the light image that non-radiopaque materials such as tissue produce. This relatively bright image aids the user of the stents or delivery systems in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the stents or delivery systems to achieve the same result.