Biliary stent

Abstract

A tissue luminal stent is provided comprising a body having an elongated tubular configuration and a deployed configuration.SOLUTION: A tissue lumen stent includes a body having an elongated tubular configuration and a deployed configuration. When deployed, each of the first end and the opposite second end of the body expands into the first and second flange structures, leaving a generally cylindrical saddle region therebetween. At least one of the first and second flange structures has at least first and second inflection points defining first and second segments of the flange structure, wherein an angle of the first inflection point defined by the first segment and the cylindrical saddle region is at least as large as an angle of the second inflection point defined by the first segment and the second segment. The first segment includes a portion of increasing diameter and the second segment includes a portion of decreasing diameter.SELECTED DRAWING: Figure 10B

Description

[Technical Field]

[0001] This application relates generally to medical methods and devices. More specifically, the present disclosure relates to lumen stents and methods of their use to maintain luminal patency through medical procedures. Summary of the Invention

[0002] Various aspects of the present disclosure generally relate to luminal stents and their methods of use for maintaining luminal patency through medical procedures. In one aspect, the present disclosure relates to a tissue lumen stent having a body with an upstream end, a downstream end, and a region therebetween, the tissue lumen stent having an elongated tubular configuration and a shortened configuration in which the upstream and downstream ends radially expand into flanged structures while the region therebetween is generally cylindrical. In some cases, when the stent is in the shortened configuration, the upstream flange structure may include a tapered portion having a maximum transverse dimension, axial width, and / or axial radius greater than that of the downstream flange structure and an axial length at least as long as the maximum diameter of the saddle-shaped region when the body is in the shortened configuration. On the other hand, some embodiments are characterized by a downstream flange structure having a maximum transverse dimension, axial width, and / or axial radius greater than that of the upstream flange structure. Alternatively, or in addition, the upstream flange structure may include a distal-most opening having a diameter greater than the maximum inner diameter of the saddle-shaped region when the body is in the shortened configuration. In some embodiments, the body includes a coated mesh, and in some cases may include both coated and uncoated mesh, while some embodiments include a cover or membrane that covers at least the cylindrical saddle portion of the stent and optionally one or both of the upstream and downstream flange structures.

[0003] In another aspect, the present disclosure relates to a tissue lumen stent including a body having an elongated tubular configuration and a shortened configuration in which the downstream end of the body radially expands into a downstream flange structure and the upstream end of the body expands distally and radially outward into a tapered configuration. The body of the stent upstream of the downstream flange structure optionally increases in diameter (i.e., tapers) continuously toward the upstream end. The upstream and downstream flange structures are optionally asymmetric, and as described above, the upstream flange structure may have a larger maximum transverse dimension, axial width, and / or axial radius than the downstream flange structure and may include a tapered portion having an axial length at least as long as the maximum diameter of the saddle-shaped region when the body is in the shortened configuration. In some cases, the upstream and downstream flange structures are substantially symmetric in the extended configuration. The stent optionally includes a cover or membrane covering the cylindrical saddle-shaped portion, and the cover or membrane may extend across one or both of the upstream and downstream flanges. In some cases, the upstream and / or downstream flange structures have a pull-out force greater than about 2.49 N.

[0004] In yet another aspect, the present disclosure relates to a method of treating a patient using a tissue lumen stent as described above. The method generally includes the steps of (a) endoscopically accessing the patient's biliary system and (b) deploying the tissue lumen stent within the patient's biliary system to a shortened configuration defining asymmetric upstream and downstream flange structures and a cylindrical portion therebetween. The method optionally includes contacting a lumen, such as the common bile duct, pancreatic duct, or hepatic duct.

[0005] The novel features of the invention are set forth with particularity in the appended claims. The features and advantages of the present invention will be better understood by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (not necessarily to scale). [Brief explanation of the drawings]

[0006] [Figure 1] Parts of the biliary and pancreatic systems are shown. [Figure 2A] 1 illustrates an exemplary stent constructed in accordance with an embodiment of the present disclosure and implanted in the common bile duct (CBD). [Figure 2B] FIG. 2B is an enlarged view of the exemplary stent shown in FIG. 2A implanted in the common bile duct CBD. [Figure 3] FIG. 2C is an enlarged side view of the exemplary stent shown in FIGS. 2A and 2B. [Figure 4] FIG. 2 is an enlarged side view of another exemplary stent. [Figure 5A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 5B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 6A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 6B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 7A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 7B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 8A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 8B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 9A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 9B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 10A] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 10B] FIG. 10 is an enlarged side view of a further exemplary stent. [Figure 11] Portions of the liver, stomach, duodenum, pancreas, and associated anatomical structures are shown. [Figure 12] Portions of the liver, stomach, duodenum, pancreas, and associated anatomical structures are shown. [Figure 13A] 1 illustrates a cross section of a stent according to some embodiments. [Figure 13B]1 illustrates a cross section of a stent according to some embodiments. [Figure 13C] 1 illustrates a cross section of a stent according to some embodiments. [Figure 13D] 1 illustrates a cross section of a stent according to some embodiments. [Figure 13E] 1 illustrates a cross section of a stent according to some embodiments. [Figure 13F] 1 illustrates a cross section of a stent according to some embodiments. [Figure 13G] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14A] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14B] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14C] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14D] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14E] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14F] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14G] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14H] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14I] 1 illustrates a cross section of a stent according to some embodiments. [Figure 14J] 1 illustrates a cross section of a stent according to some embodiments. [Figure 15A] 1 illustrates a stent according to some embodiments. [Figure 15B] 1 illustrates a stent according to some embodiments. [Figure 15C] 1 illustrates a stent according to some embodiments. [Figure 16A] 1 illustrates a cross section of a stent according to some embodiments. [Figure 16B] 1 illustrates a cross section of a stent according to some embodiments. [Figure 16C] 1 illustrates a cross section of a stent according to some embodiments. [Figure 16D] 1 illustrates a cross section of a stent according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0007] This disclosure uses the terms antegrade, retrograde, downstream, upstream, proximal, distal, inferior, upper, inferior, and superior to refer to various directions. Unless the context clearly indicates otherwise, the terms antegrade, downstream, proximal, inferior, and inferior are generally used synonymously to refer to a direction that is consistent with fluid flow and along devices and instruments toward the surgeon. Conversely, the terms retrograde, upstream, distal, superior, and superior are generally used synonymously to refer to a direction that is counter to fluid flow and along devices and instruments away from the surgeon. However, it should be noted that this nomenclature is defined herein to aid in clarity of the following description, rather than to limit the scope of the invention. While the exemplary embodiments disclosed herein focus on placement in a retrograde orientation, the disclosed methods, systems, and devices may, depending on the circumstances, be placed in an antegrade orientation. In such circumstances, the designations "upstream" and "downstream" may be reversed.

[0008] Referring to Figure 1, a typical patient's biliary system is shown. Bile, needed for food digestion, is drained by the liver into channels that carry bile to the left hepatic duct (LHD) and the right hepatic duct (RHD). These two hepatic ducts join to form the common hepatic duct (CHD), as shown. The common hepatic duct (CHD) exits the liver and joins with the cystic duct (CD) from the gallbladder (GB), which stores bile, to form the common bile duct (CBD). The common bile duct then joins with the pancreatic duct (PD) from the pancreas to deliver bile, pancreatic juice, and insulin to the descending portion of the duodenum (DD) through the ampulla of Vater (AV). A sphincter known as the sphincter of Oddi (not shown) is located at the opening of the ampulla of Vater (AV) into the duodenum (DD) and prevents material in the duodenum from traveling retrogradely upward to the common bile duct (CBD). Although the invention will be described with particular reference to a stent placed in the lower common bile duct CBD and extending into the descending duodenum DD, the principles apply to a variety of other luminal structures.

[0009] Tumor growth, hyperplasia, pancreatitis, or other strictures within or around the biliary duct tree can obstruct or block fluid flow from the liver, gallbladder, and / or pancreas to the duodenum. To alleviate the effects of the stricture, it may be necessary to place a stent in a portion of the biliary system. The stent can be placed endoscopically. One technique for placing a stent is endoscopic retrograde cholangiopancreatography (ERCP). ERCP is a technique that combines the use of endoscopy and fluoroscopy to diagnose and treat several problems in the biliary or pancreatic duct systems. This procedure involves placing an endoscope down the esophagus, through the stomach, and into the duodenum, and then passing various accessories through the endoscopic instrument channels up the ampulla of Vater into the biliary or pancreatic duct system. Alternatively, a specially narrow diameter endoscope, sometimes called a peroral cholangioscope, may be passed directly into the bile or pancreatic duct. Stents currently placed by ERCP are straight tubes that have a nearly constant diameter in their expanded state and exhibit several drawbacks that are overcome by the present disclosure, as explained below. The stents disclosed herein overcome several limitations of the straight tubes used in ERCP procedures.

[0010] In some embodiments, the stents described herein are deployed by an endoscope with ultrasound guidance. Current ultrasound endoscopes have one open lumen for passing instruments. These ultrasound endoscopes do not have additional lumens for using additional instruments. These endoscopes with ultrasound capabilities have ultrasound guidance that can be used to locate target areas in a body lumen outside the endoscope or in a body lumen with the endoscope. A procedure using ultrasound guidance may be called an EUS (endoscopic ultrasound) procedure.

[0011] In some embodiments, the stents disclosed herein are deployed using a catheter or other delivery device. Examples of catheter devices that can be used to deliver the devices disclosed herein include those disclosed in U.S. Patent Application No. 13 / 871,978, filed April 26, 2013, disclosed as U.S. Patent Application Publication No. 2013 / 0310833, and U.S. Patent Application No. 14 / 186,994, filed February 21, 2014, each of which is incorporated by reference in its entirety.

[0012] Various examples of stent configurations and shapes are shown in Figures 2A, 2B, 3, 4, 5A-5B, 6A-6B, 7A-7B, 8A-8B, 9A-9B, 10A-10B, 13A-13G, 14A-14J, 15A-15C, and 16A-16D that may be used with the methods and devices disclosed herein. The tissue anchor or stent may be made from a shape memory alloy, such as Nitinol. The stent may be self-expanding, expanding from a constrained tubular position to an expanded configuration as shown in Figures 2B, 3, 4, 5A-5B, 6A-6B, 7A-7B, 8A-8B, 9A-9B, 10A-10B, 13A-13G, 14A-14J, 15A-15C, and 16A-16D.

[0013] Referring to FIG. 2A, an exemplary biliary stent 100 configured in accordance with aspects of the present disclosure is shown implanted in the lower end of the common bile duct (CBD). In such a configuration, the stent 100 can be used to treat ampullary strictures. In other embodiments, the stent may be longer to bridge bile duct strictures located further upstream. The stent 100 includes a downstream end 102 that projects into the duodenum (DD) and an upstream end 104 that extends upward into the common bile duct (CBD). The stent 100 is shown in a generally radially expanded and axially shortened state, contacting the wall of the common bile duct (CBD) continuously or at least at some points along its length. The stent 100 can be delivered endoscopically, such as by a device similar to that described in co-pending U.S. patent application Ser. No. 13 / 363,297, filed Jan. 31, 2012. During delivery, stent 100 may be positioned in an elongate tubular configuration within a delivery sheath. Once stent 100 is determined to be properly positioned in the desired luminal location, the sheath is retracted to expose stent 100 and allow it to expand from the elongate tubular configuration to a radially expanded configuration.

[0014] Referring to FIG. 2B, there is shown a close-up view of the biliary stent 100 crossing a stricture 105 in the common bile duct CBD. Referring to FIG. 3, a biliary stent 100 is shown in its radially expanded configuration. A double-walled downstream flange 106 may be formed at the downstream end 102 as shown. The downstream flange 106 is configured to prevent upstream migration of the stent 100, such as by abutting the wall of the duodenum DD (as shown in FIG. 2). A flared upstream portion or flange 108 may be formed at the upstream end of the stent 100 as shown. A central saddle-shaped region 110 is provided between the downstream flange 106 and the upstream flange 108. In this embodiment, the saddle-shaped region has a generally constant diameter that is smaller than the maximum diameter of both the downstream flange 106 and the upstream flange 108. The upstream flange 108 is configured to prevent or inhibit downstream migration of the stent 100. The diameter of the common bile duct CBD tends to increase upstream from the ampulla of Vater AV along the common bile duct CBD. Additionally, a narrowing or other deformation in a vessel that stent 100 is intended to cross tends to have a smaller diameter compared to adjacent portions of the vessel. In some embodiments, the upstream radially outwardly extending configuration of upstream flange 108 engages the narrowed portion of the vessel to prevent or inhibit downstream movement of stent 100.

[0015] Conventional linear stents with a nearly constant diameter lack the aforementioned anti-migration features when radially expanded. To address the migration problem, conventional stents often incorporate undesirable features. For example, stents may be designed to be much longer than the stricture they are intended to cross because it is unclear where the stent will terminate, potentially resulting in migration. Because stents typically shorten as they radially expand, their final length depends on how far the stent expands within the stricture. Adding extra length to compensate for this uncertainty can cause undesirable effects, such as the downstream end protruding into the duodenum (DD). In this configuration, food migrating through the duodenum can catch on the stent, thereby bending, clogging, and / or further displacing it. The downstream end of the stent may even contact the duodenal wall opposite the opening of the common bile duct (CBD), which can also block or prevent fluid flow through the stent and / or cause tissue damage or perforation. Conventional stents that extend and / or migrate too far upstream within the common bile duct (CBD) may block one or more duct branches, such as the cystic duct (CD), left hepatic duct (LHD), and / or right hepatic duct (RHD). Stents constructed in accordance with the present disclosure may be as short as 3 cm or less and may be more precisely positioned to avoid blocking fluid flow through the duct branches. In some embodiments, the length of the stent 100 may be from about 3 cm to about 6 cm.

[0016] Conventional stents may also be uncovered or may include features that allow tissue ingrowth to prevent the stent from migrating. This configuration often results in the undesirable effect of tissue ingrowth through the stent, causing blockages that restrict or completely block flow through the stent. Tubular stents also have upstream and downstream ends that are sharp due to the termination of the wire, a condition that can cause irritation and unwanted proliferative tissue growth that can block the upstream end and restrict bile flow. Furthermore, again due to excessive tissue growth, removal of the stent can be difficult, cause undue trauma, or be impossible without causing unacceptable trauma to the duct. These adverse effects can be avoided by the stent configurations described herein.

[0017] The gentle curve of the flared upstream flange 108, shown in FIG. 3, is designed to hold the stent 100 in place without causing excessive irritation or trauma to the bile duct wall. It is believed that sharper features, such as a tight radius, a steep opening, or a steep stent end, may irritate normal tissue in the lumen wall. Such irritation can lead to hyperplasia (the rapid growth of abnormal tissue within the lumen wall to counteract the irritation). This tissue growth around the stent can cause the stent to collapse inward, thereby restricting or blocking fluid flow. If hyperplasia occurs near the ends of the stent, tissue can grow in front of and / or within the stent ends, creating new strictures that can also restrict or block fluid flow. Applicants have discovered that undesirable hyperplasia can be avoided by configuring the upstream flange 108 with a large radius, and by placing at least a slight inward curl 112 or other feature of reduced diameter at the upstream opening of the stent 100, as shown, to prevent the upstream end of the tube from contacting and abrading adjacent tissue. Because neoplastic tissue does not tend to exhibit hyperplasia, it may be advantageous to shorten the length of the stent to approximately the length of the stenosis. According to some aspects of the present disclosure, the stent may be configured to adapt to the length of the stenosis.

[0018] In some embodiments, the inner diameters of the upstream and downstream openings and the inner diameter of the saddle region are between about 5 mm and about 12 mm, while the maximum outer diameter of the upstream flange (in the deployed, radially expanded configuration) is between about 20 mm and about 30 mm. In some embodiments, the axial length of the upstream flange 108 is at least as long as the axial length of the saddle region 110. In some embodiments, the axial length of the upstream flange 108 is at least one-quarter as long as the axial length of the saddle region 110.

[0019] Referring now to FIG. 4, another exemplary embodiment is shown. The stent 114 is configured with features similar to those of the stent 100 shown in FIG. 3. A bulbous upstream flange 116 is provided to prevent or inhibit tissue trauma and downstream migration of the stent 114. In some embodiments, the upstream flange 116 includes an axial radius 118 that is at least twice the transverse radius 120 when the stent 114 is in the shortened, deployed configuration shown. As with the previous embodiment, the upstream intraluminal flange is designed to be anchored within the lumen above the stricture while minimizing tissue trauma. The knob-like "shoulder" configuration 116 distributes pressure along a larger, rounded surface area. The ends of the stent are not sharp and do not dig into tissue walls. The upstream flange 116 may be kept short to minimize contact with the normal upstream bile duct and minimize the risk of obstructing the drainage of feeding tributary ducts, such as the cystic duct and hepatic duct branches. In some embodiments, the upstream flange does not expand fully within the tube, but instead maintains an outward radial force on the tube to reduce migration.

[0020] Stents configured according to the present disclosure can be used to cross strictures virtually anywhere within the biliary and pancreatic systems. In some embodiments, the downstream end flange of the stent is always positioned in the duodenum, and the stent length is tailored to the location of the stricture. For example, a relatively short stent may be used to cross strictures at or near the ampulla of Vater. A longer stent may be used to cross strictures between the bifurcation between the left and right hepatic ducts and the cystic duct. In yet another embodiment, the stent has upstream and downstream ends configured similarly to the upstream flange 116 of FIG. 4, allowing the entire stent to be placed within the duct and bridge the stricture without extending into the duodenum. According to aspects of the present disclosure, the stent may be retrievable. In some embodiments, the stents described herein may include loops at either or both ends of the stent. The loops may facilitate retrieval of the stent using a snare or other retrieval technique. For example, a wire or filament loop can be used to capture the downstream flange in the duodenum with a snare, allowing the entire stent to be pulled out of the duct and removed through the duodenum. In another example, a loop can be used on the upstream flange in the bile duct or stomach, allowing the upstream flange to be pulled from inside the duct and removed from the body.

[0021] Stents constructed in accordance with the present disclosure may also be used to connect other lumens, such as connecting the hepatic duct or intrahepatic parenchyma to the stomach, or the pancreatic duct to the stomach, or the common bile duct to the stomach or duodenum, to allow fluid to drain from the duct if it is blocked further downstream.

[0022] The stents disclosed herein also provide advantages over conventional rigid rivet-type anastomosis devices used in the gastrointestinal tract because they securely and atraumatically engage the tissue wall and do not form necrotic tissue. In some embodiments, the stents disclosed herein can be configured to be retrievable and removable after implantation. In some embodiments, the stents can be designed for long-term or permanent implantation.

[0023] In some embodiments, stent 100 of FIG. 3 and stent 114 of FIG. 4 include a body formed from a woven filament braid. The filaments are generally metal wires, more typically nickel-titanium or other superelastic or shape-memory metal wires. Alternatively, when elasticity is not important, the filaments may be formed from polymeric materials such as polypropylene, polyethylene, polyester, nylon, PTFE, and the like. In some cases, bioabsorbable or biodegradable materials may be used, typically biodegradable polymers such as poly-L-lactic acid (PLLA).

[0024] The body can have both an elongated, tubular configuration (for stent delivery) and a shortened configuration (when deployed), in which the downstream and upstream ends of the body radially expand (concurrently shortening the body). One or both ends can expand into a double-walled flange structure. Such a "double-walled flange structure" can be formed as a portion of the body. Typically, the extreme end portions, but optionally a portion spaced inward from the end portions, move inward (toward the center), and a pair of adjacent body segments at that portion are drawn together at their bases such that their midlines or crest lines curve and expand radially, forming a pair of adjacent annular rings, which define the double-walled flange structure. See, for example, downstream flange 106 in FIGS. 3 and 4. After shortening and deployment of such a double-walled flange structure, the body can further have a cylindrical saddle-shaped region between the flange structures.

[0025] When formed from shape-memory metal wires such as nitinol or eligiloy, the wires generally have relatively small diameters ranging from 0.0254 mm (0.001 inch) to 0.508 mm (0.02 inch), usually from 0.0508 mm (0.002 inch) to 0.254 mm (0.01 inch), and the braid may contain as few as 10 to as many as 200 wires, more commonly from 20 to 100 wires. In an exemplary case, the wires may total 24 to 60 wires, have diameters ranging from 0.0762 mm (0.003 inch) to 0.1778 mm (0.007 inch), and be rounded. The wires may be braided into a tubular geometry by conventional techniques, and the tubular geometry may be heat-treated to impart the desired shape memory. Typically, the braided tube is formed into the desired final (deployed) configuration with flanges at each end. Such a flanged configuration may then be heat set or formed into the braid so that, in the absence of a radially restraining or axially elongating force, the stent will assume a shortened configuration with flanges at each end. Such a shortened memory configuration allows the stent to be delivered in a constrained configuration (radially or axially elongated) and then released from the restraint, causing the body to assume the flanged configuration at the target site.

[0026] However, in an alternative embodiment, the woven filament braid can be heat-set into an elongated, tubular configuration and shifted into a shortened, flanged configuration by applying an axial compression force. Such axial compression shortens the flanges and radially expands them, allowing for controlled and adjustable shortening, allowing the stent to be adjusted to a desired length. According to this embodiment, the woven filament braid is heat-set into an expanded configuration and can include means for mechanically shortening the stent beyond its normal, fully expanded configuration, allowing the stent to be automatically or manually adjusted to the length of the stenosis. The shortening and flanges may be formed by providing sleeves, tubes, rods, filaments, tethers, springs, elastic members, etc., which apply natural or adapted forces to the tube to cause the shortening and flange formation. Optionally or additionally, the body may have weakened regions, strengthened regions, or otherwise modified to form the desired flange geometry when a force is applied to cause axial shortening.

[0027] Stents can be adapted to be delivered by a delivery device having a small diameter, typically in the range of 1 mm to 8 mm, usually 2 mm to 5 mm, typically via an endoscopic delivery catheter. Thus, the elongated tubular configuration of the stent body typically has a diameter below the catheter diameter, typically 0.8 mm to 7.5 mm, more typically 0.8 mm to 4.5 mm, where the flange structure is significantly expanded, typically in the range of 3 mm to 70 mm, more typically 5 mm to 40 mm. Various stents of different lengths may be provided, e.g., in kit form, for use in different stricture locations. In some embodiments, the overall length of the stent in its fully expanded / deployed state is 7, 9, and 11 cm. In other embodiments, the length is 6, 8, and 10 cm. In still other embodiments, the stent length is 1 to 6 cm. The diameter of the cylindrical saddle-shaped region of the stent often does not increase during deployment, but optionally increases to a diameter of 2 mm to 50 mm, more typically 5 mm to 12 mm. The lumen or passageway of the deployed stent, when present, has a variable diameter, generally as little as 0.2 mm to as much as 40 mm, more commonly in the range of 1 mm to 20 mm, typically slightly smaller than the expanded outer diameter of the cylindrical saddle region. The length of the body can also vary significantly. Generally, when in the elongated tubular configuration, the body length ranges from 7 mm to 100 mm, usually from 12 mm to 70 mm. Upon deployment, the body can generally be shortened by at least 20%, more typically by at least 40%, and often by 70% or more. Thus, the shortened length generally ranges from 2 mm to 80 mm, usually from 30 mm to 60 mm.

[0028] The body of the stent consists of a woven filament braid without any other coverings or layers. However, in other cases, the stent may further include a membrane or other covering formed over at least a portion of the body. Often, the membrane prevents or inhibits tissue ingrowth, allowing the device to be removed after being implanted for weeks, months, or longer. Suitable membrane materials include polytetrafluoroethylene (PTFE), expanded PTFE (ePTFE), silicone, polypropylene, urethane polyether block amide (PEBA), polyethylene terephthalate (PET), polyethylene, C-Flex® thermoplastic elastomer, Krator™ SEBS, and SBS polymers.

[0029] Such a membrane may be formed over the entire stent body or only a portion of it, may be formed over the exterior or interior surface of the body, and is generally elastomeric so that the membrane conforms to the shape of the body in both the elongated and shortened configurations. Optionally, the membrane may be formed over only the central saddle region, in which case it need not be elastomeric as the central saddle region does not expand radially.

[0030] The cover or membrane prevents tissue ingrowth within the interstices of the wire mesh and minimizes fluid leakage during stent implantation. Reducing tissue ingrowth improves the ease of stent removal. In contrast to vascular stents, which are generally not designed to be displaced or retrieved, the stents shown herein are collapsible and designed to be removable and retrievable. The stents also generally do not include balls or other sharp protrusions used on some other types of stents to permanently secure the stent to the surrounding tissue.

[0031] Depending on the particular application, different portions of the stent may be coated or uncoated. In some embodiments, one end of the stent may have an uncoated portion. In some embodiments, any of the stents disclosed herein may include a covering on one of the ends of the stent. The covering may be provided on a flanged or non-flanged end of the stent. For example, if one end of the stent is deployed in the liver and the other end in the stomach, the end of the stent within the liver may be uncoated, and the end that abuts the cylindrical saddle region and the stomach may be covered. If one end is deployed adjacent to the ampulla of Vater and the duodenum and the other end in the bile duct, the end in the bile duct is covered. In some embodiments, any of the stents disclosed herein may include coverings on both ends of the stent. In some embodiments, the central portion or the portion between the upstream and downstream flanges may be uncoated. The uncoated central portion may be used to drain fluid from the pancreatic duct when the ends of the stent are placed in the duodenum and bile duct.

[0032] In some embodiments, the cylindrical saddle region is covered to prevent fluid leakage outside the cylindrical saddle region of the stent. The stents disclosed herein can be deployed within the body, whereby the cylindrical region forms a fluid conduit between body lumens within the peritoneum, as described herein. The covered cylindrical saddle region can prevent leakage into the peritoneum. Leakage of biological materials into the peritoneum can cause serious complications, and as a result, stents can have a cover to prevent leakage of fluids or materials outside the cylindrical saddle region of the stent. Covers can also be used on the ends of the stent that are configured to connect to the stomach or duodenum.

[0033] Examples of manufacturing techniques that can be used to produce the stents disclosed herein include using laser cutting, weaving, welding, etching, and wire forming. A membrane material, such as silicone, is applied to the wire stent frame to prevent fluid from passing through the stent wall. The membrane or cover material can be applied by painting, brushing, spraying, dipping, or molding.

[0034] The strength of the double-walled flanged structure(s) depends on the number, size, stiffness, and weave pattern(s) of the individual wires used to form the tubular stent body. For example, a design using a large number of nitinol wires, e.g., 48, but with a relatively small wire diameter, e.g., 0.006 inches (0.1524 mm), produces a braided structure with a flexible saddle region and one or more relatively stiff double-walled flanges. Using fewer wires, e.g., 16, and a larger wire diameter, e.g., 0.016 inches (0.4064 mm), produces a braided structure with a relatively stiff saddle region and one or more relatively rigid, inflexible flanges. Both stiff and flexible designs may be desirable depending on the application. In particular, in some embodiments, the double-walled flange(s) have a preselected bending stiffness in the range of 1 g / mm to 100 g / mm, or in the range of 4 g / mm to 40 g / mm. Similarly, in some embodiments, the central saddle region has a preselected bending stiffness in the range of 1 g / mm to 100 g / mm, or 10 g / mm to 100 g / mm.

[0035] The bending stiffness of the flange may be determined by the following test: The distal flange is secured in a fixture. The outer diameter of the flange is pulled in a direction parallel to the axis of the stent using a hook attached to a Chatillon force gauge. The saddle portion of the stent is held in a hole in the fixture and the force (grams) and deflection (mm) are measured and recorded. The bending stiffness of the flange may be determined by the following test: The distal flange is secured in a fixture. The outer diameter of the flange is pulled in a direction perpendicular to the axis of the stent using a hook attached to a Chatillon force gauge. The saddle portion of the stent is held in a hole in the fixture and the force (grams) and deflection (mm) are measured and recorded.

[0036] The shape and design of the stent can be selected based on the desired application. For example, embodiments of the stents and methods disclosed herein include forming a direct fluid conduit between commonly unconnected body lumens (e.g., the stomach and gallbladder). In these embodiments, the ends or flanges of the stent can be selected to provide sufficient strength and flexibility to maintain tissue planes. In some embodiments, the stents and methods disclosed herein can be used to improve flow through natural pathways within the body. In these embodiments, the shape and design of the stent can be selected based on the desired characteristics for these applications.

[0037] The stent design also has improved lateral strength and pull-out force over conventional stents. Pull-out force can be determined using two different tests: the stent pull-out force test and the implant anchor pull-out test.

[0038] In the pull-out force test, the stent is tested in its fully expanded configuration. The stent is deployed through a hole in a material sized to fit the expanded diameter of the cylindrical saddle region of the stent. For example, the hole in the material can be approximately 10 mm or 15 mm, depending on the stent size. The stent pull-out test measures the force required to deform the distal flange of a fully expanded stent and pull the expanded distal flange of the stent through the opening. The stent is pulled proximally using a fastener attached to a force gauge. A proximal force is applied until the distal flange is detached from the material, and the removal force, measured in grams, is measured and recorded as the "pull-out force," and the deflection, measured in mm, is measured and recorded. In some embodiments, the stent pull-out force is greater than approximately 260 grams (approximately 2.55 N). In some embodiments, the stent pull-out force is greater than approximately 300 grams (approximately 2.94 N). In some embodiments, the stent pull-out force is greater than approximately 400 grams (approximately 3.92 N). In some embodiments, the stent pull-out force is greater than about 500 grams (about 4.9 N). In some embodiments, the stent pull-out force is greater than about 550 grams (about 5.39 N). In some embodiments, the stent pull-out force is greater than about 600 grams (about 5.88 N). In some embodiments, the stent pull-out force is greater than about 700 grams (about 6.86 N). In some embodiments, the stent pull-out force is greater than about 800 grams (about 7.84 N). In some embodiments, the stent pull-out force is greater than about 900 grams (about 8.82 N). In some embodiments, the stent pull-out force is greater than about 1000 grams (about 9.8 N).

[0039] The implant adhesion test tests the strength of the distal flange of a stent when the proximal flange is held in a constrained position by a catheter device. The distal flange is deployed on the other side of a rigid material having a hole sized to fit the catheter shaft. The catheter can be pulled with the measured force required to deform the distal flange and pull it through the hole in the rigid material. In some embodiments, the stent has an implant adhesion test strength greater than about 1 N. In some embodiments, the stent has an implant adhesion test strength greater than about 2 N. In some embodiments, the stent has an implant adhesion test strength greater than about 3 N. In some embodiments, the stent has an implant adhesion test strength greater than about 4 N. In some embodiments, the stent has an implant adhesion test strength greater than about 5 N. In some embodiments, the stent has an implant adhesion test strength greater than about 6 N. In some embodiments, the stent has an implant adhesion test strength greater than about 7 N. In some embodiments, the stent has an implant adhesion test strength greater than about 8 N. In some embodiments, the stent has an implant bond test strength of greater than about 9 N. In some embodiments, the stent has an implant bond test strength of greater than about 10 N. In some embodiments, the stent has an implant bond test strength of greater than about 15 N.

[0040] Stent shapes can vary. Figures 2A, 2B, 3, 4, 5A-5B, 6A-6B, 7A-7B, 8A-8B, 9A-9B, 10A-10B, 13A-13G, 14A-14J, 15A-15C, and 16A-16D show various stent shapes and cross sections. For example, the end or flange shape can be optimized to improve the strength of the stent and provide a sufficient amount of linear force against each tissue plane while allowing smooth fluid and material flow through the inner opening of the composite structure. In some embodiments, the end shape can be described as "bell-shaped," consisting of multiple structural folds and having multiple inflection points. An inflection point can be thought of as a point on the curve where a change in the direction of curvature occurs. Additional end portions can be rolled or protrude against the tissue plane. An alternative design may consist of an opening wider than the inner diameter of the device.

[0041] In some embodiments, both ends of the stent are symmetrical. In some embodiments, both ends of the stent can have different end geometries. The stent end geometries can be selected based on the body lumen and location where the stent will be deployed, as well as the desired physical characteristics. The stent can be designed to facilitate unidirectional flow of fluids and materials. Unidirectional flow can also provide or require additional strength in the leading stent flange (e.g., the upstream flange), which first contacts the flowing material. The upstream flange can be designed with a cross-section that has a stronger pull-out force than the downstream flange. The diameter of the opening in the upstream flange can be designed wider than the downstream flange to minimize the possibility of fluids or materials getting trapped within the flange. The end of the upstream flange can also be designed to further reduce the possibility of fluids or materials getting trapped in the flange. For example, the stent can have the cross-section shown in FIG. 14A with its wide flange end on the upstream flange, and the flange design shown in FIG. 14I on the downstream flange, as shown in FIG. 14J.

[0042] Any of the stents disclosed herein may include a windsock-type structure. The windsock structure may encourage unidirectional fluid flow from the interior of the stent through the windsock, while preventing or minimizing the flow of materials through the windsock into the interior of the stent. The windsock may be attached to the downstream end of the stent. The windsock may have a length suitable for a particular application and a desired fluid flow path. For example, the windsock may have a length sized to extend from the duodenal region to the jejunum. In some embodiments, the stent is configured such that the upstream end is sized to deploy in the bile duct or pancreatic duct and the downstream end is located in the duodenum adjacent to the ampulla of Vater, with the windsock attached to the downstream end and extending from the duodenum to the jejunum. In this embodiment, digestive fluids flow from the upstream end of the stent in the pancreatic or bile duct through the stent and windsock to the jejunum, thereby passing through the duodenum. The windsock may also have a length sized to extend from the stomach region to the jejunum. In some embodiments, the stent is sized so that its upstream end is deployed in the bile duct, pancreatic duct, or liver, and its downstream end is configured to reside in the stomach with a windsock attached to the downstream end and extending from the stomach to the jejunum. In this embodiment, digestive fluids flow from the upstream end of the stent in the pancreatic duct, bile duct, or liver through the stent and windsock to the jejunum, thereby passing through the stomach and duodenum. These exemplary applications may provide benefits associated with gastric bypass procedures (Roux-en-Y procedure) without the need for the invasive surgery used in gastric bypass procedures.

[0043] The dimensions of the stent can be designed to provide the desired retention at the tissue wall along with the desired conduit for fluid flow. For example, the width and diameter of the flanges can be optimized to provide the desired characteristics. Cuffs or lips can be provided at the tips of the flanges to provide additional strength. The diameter and length of the cuffs can also be optimized to modify the characteristics of the stent. The diameter of the cuffs can be larger than the diameter of the cylindrical hollow portion. This can facilitate subsequent access to the stent and reduce the chance of material getting trapped within the flange. The cuffs or outer lips can also be shaped to minimize the chance of fluids or material getting trapped within the flange volume. For example, the outer cuff or lip can include a wall that protrudes or curls away from the interior volume of the stent. The diameter and length of the cylindrical portion can be optimized based on the thickness of the tissue wall and the desired stent location. The overall length of the stent can also be optimized based on the particular application.

[0044] In some embodiments, any of the flange cross sections disclosed herein can be used with any of the other stent flanges or cross sections disclosed herein. For example, flange 106 shown in Figures 8A-8B can be replaced with any of the flanges shown in Figures 13A-153, 14A-14J, 15A-15C, and 16A-16D, such that the stent has the flange of Figures 13A-13G, 14A-14J, 15A-15C, and 16A-16D and a cylindrical portion 156 at the other end. In another example, flanges 164, 164A of Figures 10A-10B can be replaced with any of the flanges shown in Figures 13A-13G, 14A-14J, 15A-15C, and 16A-16D.

[0045] In some embodiments, the self-expanding stent body is formed from a shape memory alloy, while other designs can use elastic tethers connecting the ends of the body. The body can therefore have a low elasticity, where the force compressing the ends axially comes from the elastic tether. Such designs can be particularly suitable when polymeric or other less elastic materials are used for the stent body.

[0046] In yet other embodiments, the stent can include a lock that maintains the body in a shortened configuration. For example, the lock can include a rod or cylinder within the body that engages both ends of the body when the body is shortened. Alternatively, the lock can include one, two, or more axial members that clamp the lumen of the stent body when the body is shortened.

[0047] As yet another option, the stent may include a sleeve formed over a portion of the cylindrical saddle region, which maintains the diameter of the central saddle region and limits the inward extension of the flanges, helping to form the flanges when the stent body is axially shortened.

[0048] 5A-10B, additional stent embodiments are shown that utilize similar features to those described above. FIG. 5A shows another exemplary stent 130 having an upstream flange 132 that is generally cylindrical in shape and has rounded portions at the proximal and distal ends of the upstream flange 132 .

[0049] The stents disclosed herein can include covered and uncovered portions. Figure 5B shows a stent 130' similar to Figure 5A, but with a portion of the saddle region 110' uncovered. By leaving only a portion of the stent uncovered, a limited amount of tissue ingrowth can prevent stent migration, but at least allow for removal of the stent within a limited period of time. In another similar embodiment, the upstream and / or downstream ends of the stent can be uncovered to allow unobstructed fluid flow from side branches of the duct system, such as the cystic duct and pancreatic duct.

[0050] In some embodiments, the covered portion of the stent may be as little as about 20% of the stent. For example, in a stent having one end configured to engage the stomach and a second end configured to engage another body lumen, as little as about 20% of the stent may be covered. The covered portion may be the portion of the stent configured to engage the stomach, such as the stomach end of the stent.

[0051] The uncoated portion of the stent allows fluid to flow into the interior region of the stent and through it to the other end of the stent. For example, the uncoated end of the stent may be placed in the liver. Pressure from the bile in the liver causes bile to flow through the uncoated portion of the stent, through the stent's lumen, and into another body lumen, such as the stomach or duodenum, where the other end of the stent is secured. The portion of the stent that engages the stomach or duodenum may be coated to minimize tissue ingrowth and improve fluid flow and delivery to the stomach. FIG. 6A shows another exemplary stent 136. The body 138 of the stent upstream of the downstream flange 106 gradually increases in diameter. FIG. 6B shows a similar stent 136' having a portion 140 of the body 138' that is uncoated, similar to the stent shown in FIG. 5B.

[0052] Figure 7A shows another exemplary stent 142. Stent 142 includes a double-walled downstream flange 144 and a double-walled upstream flange 146. The inward-facing wall of upstream flange 146 is configured to be flatter than the outward-facing wall. Figure 7B shows a similar stent 142' having an uncoated portion 148 in its saddle region 110'.

[0053] FIG. 8A shows another exemplary stent 150. The stent 150 includes an upstream flange 152 with a beveled portion 154 that connects to a cylindrical portion 156. FIG. 8B shows a similar stent 150' with an uncoated beveled portion 154'. In some embodiments, the stent 150' can be used to drain a portion of the liver or associated duct system. The uncoated beveled portion 154' and cylindrical portion 156' can be implanted or deployed within the liver. The uncoated beveled portion 154' allows bile to flow from the duct system and other areas of the liver, where it can flow to the other end of the stent, which is deployed into a body lumen, such as the stomach or duodenum. The stent 150' shown in FIG. 8B has an uncoated portion (shown as the uncoated beveled portion 154') that can be used to facilitate drainage. The stent 150' can be deployed between the bile duct and the duodenum, with the downstream flange 106 deployed in the duodenum and the cylindrical portion 156' deployed in the bile duct. The uncoated beveled portion 154' allows material to flow from the pancreatic duct, through the interior of the stent, and out an outlet adjacent the downstream flange 106 into the duodenum.

[0054] Figure 9A shows another exemplary stent 158. Stent 158 ​​includes a double-walled downstream flange 144 and an identical double-walled upstream flange 144. Figure 9B shows a similar stent 158' with an uncoated downstream flange 144' and an uncoated upstream flange 144'.

[0055] Figure 10A shows another exemplary stent 160. Stent 160 includes a small diameter, double-walled downstream flange 162 and a larger diameter, double-walled upstream flange 164. Figure 10B shows a similar stent 160' with an uncoated upstream flange 164'.

[0056] FIG. 13A shows a cross section of an embodiment of a stent 150 including a cylindrical saddle region 151, a flange 152 with an end 153 configured to bend back toward the flange 154, and a flange 154 with an end 155 configured to bend back toward the flange 152. The flanges 152, 154 and the ends 153, 155 are configured to hold the tissue walls T1, T2 in juxtaposition. The distal portions of the flanges 152, 154 are bent to reduce trauma to the tissue walls. FIGS. 13B and 13C show a similar configuration to FIG. 13A , but with the stent's ends 153, 155 additionally rounded. FIG. 13B shows the ends 153, 155 rounded into approximately a semicircle, and FIG. 13C has the ends 153, 155 forming approximately a full circle. The ends 153, 155 of the stent in Figures 13B-C may atraumatically engage tissue and provide added strength from further rounding the tips of the stent structure.

[0057] Figures 13D-13G show additional cross-sectional views of stent structures. Figure 13D shows a stent 150 with flange structures 152, 154 that protrude away from a cylindrical saddle-shaped region 151. The cylindrical saddle-shaped region 151 has a diameter D1, and the outer flange structures 152, 154 have a larger diameter D2. Figure 13E shows a stent 150 with flange structures 152, 154 that curl outward and away from the interior volume of the cylindrical saddle-shaped region 151. Figure 13F shows flange structures 152, 154 that protrude away from the cylindrical saddle-shaped region 151 and have rounded ends 153, 155. The rounded ends may provide additional lateral strength to the stent. FIG. 13G shows flange structures 152, 154 that protrude away from the interior volume of cylindrical saddle region 151 and further include double-walled flange structures to increase the strength of stent 150 and further atraumatically engage tissue walls during implantation.

[0058] 14A-14J show various partial cross sections of stent flange configurations. Some flange designs may have volumes within each flange that can trap fluids or other materials passing through the stent. The flanges may be designed to minimize the possibility of fluids or other materials becoming trapped within the stent's internal volume or the stent flanges. The stent shown in FIGS. 14A-14I has flange designs designed to minimize fluids and materials becoming trapped or trapped within the flange volumes.

[0059] FIG. 14A shows a partial cross section of a stent 160 in which the flange structure 162 has multiple inflection points. The inflection points create radial bends in the three-dimensional stent structure. The wall of the flange 162 protrudes away from the cylindrical saddle region 161 (first inflection point), then bends back toward the center of the longitudinal path 164 of the stent 160 (two additional inflection points), then bends back away from the center of the longitudinal path 164 of the stent 160 again (two additional inflection points), and further bends at the stent end 163 (one additional inflection point). Each bend can be considered an inflection point. The stent 160 shown in FIG. 16A has six inflection points. The inflection points can add additional strength to the stent flanges. The stent may have an open end with a diameter larger than that of the cylindrical saddle region 161 to reduce the possibility of material becoming trapped within the stent and to promote fluid flow through the stent body. The additional inflection points increase the lateral strength and pull-out force of the expanded stent.

[0060] Figure 14B shows a stent 160 in which the flange structure 162 has seven inflection points. The structure is similar to the stent shown in Figure 14A, but the outer stent wall is angled back toward the center of the longitudinal path 164 at the ends 163.

[0061] 14C shows a stent 160 in which a flange structure 162 has rounded stent ends 163. The rounded ends are rolled back toward a cylindrical saddle region 161, forming a circular cross section. Because the stent flange ends 163 are curved back toward themselves, fluid flow does not occur directly at the ends of the stent. This stent configuration also reduces the likelihood of fluid becoming trapped within the interior volume of the flange 162.

[0062] FIG. 14D shows a stent 160 in which flanges 162 project away from longitudinal paths 164 of saddle region 161 and ends 163 curl outward beyond the outer points of flanges 162 .

[0063] 14E shows a stent 160 in which flanges 162 have five inflection points. The flanges 162 bulge outward away from the center of the saddle region 161, then bend back toward the central passage 164, and then bend again so that the ends 163 bulge away from the longitudinal center 164 of the cylindrical saddle region 161.

[0064] FIG. 14F shows a stent 160 in which flanges 162 project away from a cylindrical saddle region 161 and form a rounded circular cross section with rounded ends 163 that extend back toward the flanges 162 .

[0065] FIG. 14G is similar to FIG. 14F, except that the circular end 163 is more than a full circle at the end 163 of the stent. 14H shows a stent flange 162 having multiple bends resembling right angles, with rounded ends 163 that curl away from a cylindrical central region 161. The right angles can increase the lateral strength and pull-out force of the stent.

[0066] Figure 141 shows a flange with a sinusoidal outer shape, with the rounded ends curling away from the cylindrical saddle region. The wavy sinusoidal outer shape can increase the lateral strength and pull-out force of the stent.

[0067] Figure 14J shows a cross section of a stent with one flange having the structure shown in Figure 14A and the flange shown in Figure 14I. The flange shown in Figure 14A can be deployed wide open and facing the direction of fluid flow. The flange shown in Figure 14I can be used as the opposing end with a narrow outer end where material exits the interior volume of the stent.

[0068] 15A-15B show a cross-sectional view and an exterior view, respectively, of a stent 170 according to some embodiments. The flange structure 171 initially protrudes outward, away from the stent body, and then curls back toward the interior volume of the cylindrical saddle region 172 to form a semicircular flange configuration. The flange provides additional lateral strength and increases pullout force while minimizing the possibility of material or fluid becoming trapped within the flange's interior volume. FIG. 15C shows an alternative configuration in which the semicircular flange structure 171 curls back toward the cylindrical saddle region 172.

[0069] The stent structures shown in Figures 16A-16D may be referred to as double-walled flange structures. Figure 16A shows a stent 180 with a flange 181 that includes a cylindrical saddle region 182 and a relatively large, open cylindrical region, and with a wide cuff or lip 183 on the flange structure 181. Figure 16B shows a stent 180 with a smaller inner diameter than Figure 16A, but with a larger double-walled flange 181 that atraumatically engages tissue. Figure 16C shows a stent 180 with an outer cuff or lip 183 that is larger in diameter than the inner cylindrical saddle region.

[0070] 16D shows an embodiment of a stent 180 similar to FIG. 16C but including a separate plug 184 in the flange 181 to prevent fluids or substances from becoming lodged within the flange volume. The plug may be made of a material suitable for flowing or passing through the digestive tract after the stent is removed. In some embodiments, the flange may be made of a biodegradable or bioabsorbable material. The flange plug structure may be used with any of the stent structures disclosed herein.

[0071] In an exemplary EUS procedure, an endoscope equipped with ultrasound capabilities is advanced through the mouth, down the esophagus, and into the stomach. An ultrasound target may optionally be placed within the target body lumen. There are many ways to create an ultrasound target, for example, an infusion catheter may be used to inject a large amount of saline, which may be identified by ultrasound. Ultrasound guidance is used to advance a needle through the working channel of the endoscope to first puncture the stomach wall and the wall of the target body lumen, followed by advancing a guidewire into the target body lumen. A catheter device carrying a stent may follow the guidewire to gain access to the target body lumen. In this embodiment, needle access is preferred. However, in some embodiments, a catheter can be used to initially penetrate the stomach wall and target body lumen directly using an actuated distal tip, without the use of a needle and guidewire (such catheter devices are disclosed in U.S. Patent Application No. 13 / 871,978, filed April 26, 2013, published as U.S. Patent Application Publication No. 2013 / 0310833, and U.S. Patent Application No. 14 / 186,994). After gaining access to the target body lumen, the catheter device can deploy the upstream end of the stent within the target body lumen by withdrawing or retracting the sheath that restrains the stent. The downstream end of the stent can then be deployed into the stomach by continuing to retract the sheath that restrains the stent. After stent deployment, a pathway is formed between the stomach and the target body lumen through the interior of the stent. The delivery catheter is removed, and the stent can optionally be expanded. After stent deployment, the endoscope is removed. The stent is later removed endoscopically using a snare or other known techniques. A similar technique can be used in conjunction with an ERCP procedure with an endoscope positioned in the duodenum.

[0072] As described above, any of the stents disclosed herein can be used in an ERCP procedure. The ERCP procedure can include advancing an endoscope through the mouth and stomach into the intestine. The endoscope can be advanced to a region of the intestine adjacent to the ampulla of Vater. A guidewire can be advanced through the working channel of the endoscope, into the ampulla of Vater, and into the common bile duct or pancreatic duct. A catheter carrying a self-expanding stent can be advanced over the guidewire to gain access to the common bile duct or pancreatic duct. The catheter retracts the sheath to allow the self-expanding stent to expand. The sheath can be partially retracted to expand the first or upstream end of the stent within the common bile duct or pancreatic duct. After the upstream end is deployed, the sheath can be further retracted to deploy the second or downstream end of the stent. The downstream end of the stent can be deployed in the ampulla of Vater, other regions of the intestine, or common bile duct, or the pancreatic duct. The cylindrical saddle region of the stent forms a fluid conduit or pathway between the common bile duct or pancreatic duct and the ampulla of Vater, the intestine, or other regions of the common bile duct or pancreatic duct.

[0073] Figures 11 and 12 show additional examples of body lumens that may be connected by the stents disclosed herein. The arrows in Figures 11 and 12 indicate areas of the abdominal cavity where a stent extends to connect the common bile duct to the duodenum (e.g., Figure 11, #3) or the stomach to various locations within the biliary tree. Figures 11 and 12 show areas within the abdominal cavity where a stent extends between the stomach and the duodenum and other areas of the biliary tree.

[0074] FIG. 11 shows various numbered locations 1-6 where a stent may be placed within the abdominal cavity. In some embodiments, any of the stents disclosed herein may be placed at any of the locations shown in FIGS. 11 and 12. For example, any of the techniques shown in FIGS. 11 and 12 may be used in place of an ERCP procedure. In some cases, an ERCP procedure may fail or be impossible; in these cases, a stent can be placed through any of the pathways shown in FIGS. 11 and 12.

[0075] In some embodiments, the stents disclosed herein can be used in a choledochoduodenal anastomosis, such as that shown in FIG. 11, #3, which connects the common bile duct to the duodenum. In a choledochoduodenal anastomosis, an endoscope can be advanced through the mouth and stomach into the duodenum. A target location in the common bile duct can be identified using ultrasound or other guidance methods. A needle or catheter device can be advanced through the endoscope to puncture the duodenal wall and the common bile duct. If a needle is used to access the common bile duct, a guidewire can be advanced over the guidewire with the catheter accessing the common bile duct. The catheter can then deploy the stent with its upstream end or flange in the common bile duct and its downstream end or flange in the duodenum, thereby forming a fluid conduit between the common bile duct and the duodenum.

[0076] In some embodiments, the stents disclosed herein can be used in hepatogastric anastomosis, which connects the hepatic duct to the stomach. The arrows in Figures 11 (#1) and 12 indicate the area within the abdominal cavity where the stent connects the hepatic duct to the stomach. An endoscope can be advanced through the mouth to the stomach. A target location within the liver can be identified using ultrasound or other guidance methods. A needle or catheter device can be advanced to puncture the stomach and liver. A guidewire can be placed within the liver (after needle access), followed by advancing a catheter carrying a stent over the guidewire. The upstream end of the stent can be positioned within the liver and hepatic duct using a catheter. The downstream end of the stent is deployed within the stomach. The stent can have an uncoated portion at the end of the stent that is released within the liver and hepatic duct. For example, the upstream end deployed within the liver can have an uncoated portion of approximately 3 to 4 cm. The uncoated portion on the end of the stent can encourage bile to drain from the liver and through the interior volume of the stent to the stomach. Pressure within the liver can assist in the drainage of bile from the liver through the stent to the stomach. The downstream end of the stent deployed in the stomach can be coated to reduce contact between bile and the stomach wall.

[0077] Route #2 in Figure 11 shows an alternative access route for accessing the common bile duct and subsequently placing an intraluminal stent within it. In some cases, ERCP can fail approximately 1% of the time. If the ERCP procedure fails, alternative access to the common bile duct is necessary. As shown in #2 in Figure 11, the hepatic duct can be accessed by advancing a needle through the stomach and liver wall to puncture the hepatic duct. A guidewire can then be passed through the hepatic duct and common bile duct. Bile flow can assist in advancing the guidewire through the common bile duct and into the ampulla of Vater and duodenum. Forceps or other surgical instruments can be used to grasp the end of the guidewire within the duodenum. The forceps or other surgical instrument can then be used to withdraw the end of the guidewire from the patient's mouth. Once the end of the guidewire exits the patient's body, a catheter can be advanced over the guidewire. The catheter can be advanced through the stomach, duodenum, ampulla of Vater, and into the bile duct. After the catheter has access to the common bile duct, ERCP steps can be performed, such as cutting the ampulla of Vater, extracting stones, addressing strictures, etc. This type of procedure can be called a rendezvous procedure. The catheter can also be used for additional medical procedures, such as placement of any of the stents disclosed herein, as desired.

[0078] Path #4 illustrates another type of rendezvous procedure. A needle may be advanced into the duodenum. The bile duct may be located and targeted with the needle. The needle may then be advanced through the wall of the duodenum into the bile duct. A guidewire may then be passed from the needle into the bile duct. The guidewire may be advanced through the bile duct to the ampulla of Vater and into the duodenum. In the duodenum, the guidewire may be grasped using forceps or other surgical instruments and withdrawn through the mouth. Once the end of the guidewire exits the patient's body, a catheter may be advanced over the guidewire. The catheter may be advanced through the stomach and duodenum into the bile duct. The catheter may then be used for additional medical procedures, such as placing any of the stents disclosed herein, as desired.

[0079] Pathway #5 shows a path through the pancreatic duct for a rendezvous procedure. A needle may be advanced into the stomach. The pancreatic duct may be located and targeted by the needle. The needle is then advanced through the stomach wall into the pancreatic duct. A guidewire may then be passed from the needle into the pancreatic duct. The guidewire may be advanced through the pancreatic duct into the ampulla of Vater and the duodenum. The guidewire may be grasped in the duodenum using forceps or other surgical instruments and withdrawn from the mouth. Once the end of the guidewire exits the patient's body, a catheter may be advanced over the guidewire. The catheter may be advanced through the stomach and duodenum into the pancreatic duct. The catheter may then be used for additional medical procedures, such as placing any of the stents disclosed herein, as desired.

[0080] In some embodiments, the stents disclosed herein can be used in pancreaticogastrostomy, which connects the pancreatic duct to the stomach. The arrows in Figures 11 (#6) and 12 indicate the area within the abdominal cavity through which the stent extends to connect the pancreatic duct to the stomach. In a pancreaticogastrostomy, an endoscope can be advanced through the mouth into the stomach. A target location within the pancreatic duct can be identified using ultrasound guidance or other guidance methods. A needle or catheter device can be advanced from the endoscope to puncture the stomach wall and pancreatic duct. A guidewire can be placed within the pancreatic duct (after needle access), followed by advancing a catheter carrying a stent over the guidewire. The upstream end of the stent can be positioned within the pancreatic duct using the catheter. The downstream end of the stent is deployed within the stomach, thereby forming a fluid conduit between the pancreatic duct and the stomach.

[0081] In some embodiments, the stents disclosed herein can be used for antegrade stent placement. Antegrade stent placement can be performed in the bile duct and pancreatic duct. Antegrade stent placement is when the operator enters the upstream portion of the bile duct (or pancreatic duct). The upstream portion of the bile duct can be accessed percutaneously (e.g., transhepatically) or under EUS guidance (e.g., transenterically targeting the intrahepatic or extrahepatic bile duct—see route #2 in Figure 11). After gaining access to the upstream portion of the bile duct, a guidewire is inserted and advanced downstream, crossing the stricture and ampulla, and advanced into the duodenum. The stent is then advanced antegrade over the wire, crossing the stricture and ampulla until the downstream end of the stent is in the duodenum. The sheath is retracted relative to the stent to release the downstream flange or double-walled flange. The sheath and stent may then be retracted as a single unit until the flange abuts the ampulla of Vater, indicated by resistance encountered by the retraction. The sheath is then retracted relative to the stent, deploying the upstream flange within the bile duct. A similar technique can be used to place a stent antegrade into the pancreatic duct after gaining upstream access to the pancreatic duct (see Figure 11 #5 pathway).

[0082] According to an additional aspect of the present disclosure, a two-flanged ERCP stent, which may be shorter than those described herein above, is temporarily inserted into the lower end of the common bile duct to facilitate passage of an endoscope into the bile duct. Such an arrangement facilitates insertion of a cholangioscope into the bile or pancreatic duct for cholangioscopy or pancreatic duct ("ductoscopy"). Entering the duct is typically very difficult due to the duct's acute angle to the duodenum, i.e., the duct's axis is at a 90-degree angle to the axis of the duodenum. The temporary stent fits into the stent's opening, stabilizing the scope's advancement into the duct, rather than fitting the scope directly into the duct's opening.

[0083] In the above-mentioned ductoscopy, a short stent can be used because there is no stenosis to bridge, only the ampulla / sphincter of Oddi. The diameter of the stent can be 8 mm to allow for the insertion of a very small gastroscope (e.g., 6 mm in diameter). After the stent is inserted, the duodenoscope can be removed and replaced with a "transnasal" gastroscope. This scope, although longer than a standard gastroscope, is inserted orally. This technique can be called "direct per oral cholangioscopy." The stent can be removed immediately after the ductoscopy is performed.

[0084] Short ERCP stents may also be suitable for treating "dyskinesis of the sphincter of Oddi," a condition in which repeated spasms in the sphincter increase pressure in the bile duct and result in pain. Even after sphincterotomy, the ampulla opening continues to scar and obstruct bile flow, causing pain.

[0085] While the above is a complete description of exemplary embodiments of the present disclosure, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be deemed to limit the scope of the disclosure, which is defined by the appended claims and the claims of any subsequent application to which priority is claimed.

[0086] When a feature or element herein is referred to as being "on" another feature or element, it can be directly on the other feature or element, or there may be intervening features and / or elements. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. When a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it should also be understood that it can be directly connected, attached, or coupled to the other feature or element, or there may be intervening features or elements present. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or illustrated with respect to one embodiment, the features and elements so described or illustrated may also be applicable to other embodiments. Those skilled in the art should also recognize that references to structures or features located "adjacent" another feature may have overlapping portions above or below the adjacent feature.

[0087] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. For example, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. It should be further understood that as used herein, the term "comprising" specifies the presence of stated features, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ".

[0088] Spatially relative terms, such as "lower," "below," "below," "above," "upper," etc., may be used herein for ease of description to describe the relationship of one element or feature to another element or feature or features as shown in the drawings. It is understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in the drawings is inverted, elements described as being "below" or "directly below" the other element or feature would be oriented "above" the other element or feature. Thus, the exemplary term "lower" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein will be interpreted accordingly. Similarly, the terms "upper," "lower," "vertical," "horizontal," etc., are used herein for descriptive purposes only, unless specifically indicated otherwise.

[0089] The terms "first" and "second" may be used herein to describe various features / elements, but these features / elements should not be limited by these terms unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another. Thus, a first feature / element described below could be referred to as a second feature / element, and similarly, a second feature / element described below could be referred to as a first feature / element, without departing from the teachings of the present invention.

[0090] As used herein, including when used in the examples, throughout the specification and claims, and unless expressly specified otherwise, all numbers may be read as if preceded by the word "about" or "approximately," even if those terms do not expressly appear. The terms "about" or "approximately" may be used when describing a size and / or location to indicate that the stated value and / or location is within a reasonably expected range of values ​​and / or locations. For example, a numerical value may have a value of ±0.1% of the stated value (or range of values), ±1% of the stated value (or range of values), ±2% of the stated value (or range of values), ±5% of the stated value (or range of values), ±10% of the stated value (or range of values), etc. Any numerical range cited herein is intended to include all subranges contained therein.

[0091] While various illustrative embodiments have been described above, any of numerous modifications to the various embodiments may be made without departing from the scope of the invention as set forth in the claims. For example, the order in which various illustrative method steps are performed is often changed in alternative embodiments, and in other alternative embodiments, one or more method steps may be omitted entirely. Optional features of the various apparatus and system embodiments may be included in some embodiments but not in other embodiments. Therefore, the above description has been provided primarily for purposes of illustration and should not be construed as limiting the scope of the invention as set forth in the claims.

[0092] The examples and illustrations included herein show, for purposes of explanation and not limitation, specific embodiments in which the subject matter may be practiced. As noted above, other embodiments may be utilized and derived therefrom, and structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Such embodiments of the inventive subject matter are referred to herein, individually or collectively, with the term "invention," merely for convenience, and are not intended to intentionally limit the scope of this application to any single invention or inventive concept, if more than one is actually disclosed. Thus, while specific embodiments have been shown and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover all adaptations or variations of the various embodiments. Combinations of the above-described embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art upon reviewing the above description.

Claims

1. A tissue lumen stent comprising a main body having a long, tubular structure and an unfolded structure, When the main body is in the deployed configuration, the first end and the second end on the opposite side of the main body extend radially to a first flange structure and a second flange structure, respectively, leaving a substantially cylindrical saddle-shaped region between the first flange structure and the second flange structure. The first flange structure and the second flange structure each include an inward curl at their distal ends. A tissue lumen stent in which the first flange structure and the second flange structure are configured to hold tissue walls in parallel.

2. The tissue lumen stent according to claim 1, wherein the inward curl at the distal end of the first flange structure and the second flange structure is bent to reduce trauma to the tissue wall.

3. The tissue lumen stent according to claim 1, wherein the first flange structure and the second flange structure are substantially symmetrical with respect to the central plane of the cylindrical saddle region in the deployed configuration.

4. The tissue lumen stent according to any one of claims 1 to 3, further comprising a cover or membrane covering the cylindrical saddle region, wherein the inward curl of the distal end of at least one of the first flange structure and the second flange structure is not covered.

5. The tissue lumen stent according to any one of claims 1 to 4, wherein in the deployed configuration, the maximum diameter of the cylindrical saddle region is 5 mm to 20 mm, and the maximum diameters of the first flange structure and the second flange structure are 20 mm to 40 mm, respectively.

6. The tissue lumen stent according to any one of claims 1 to 5, wherein the elongated tubular structure has a maximum diameter of 0.8 mm to 4.5 mm.

7. A tissue lumen stent comprising a main body having an elongated tubular structure and an unfolded structure, When the main body is unfolded into the tissue in the unfolded configuration, the first end and the opposite second end of the main body extend radially into a first flange structure and a second flange structure, respectively, leaving a substantially cylindrical saddle-shaped region between the first flange structure and the second flange structure. At least one of the first flange structure and the second flange structure includes an inward curl at its distal end. A tissue lumen stent in the deployed configuration, wherein the maximum diameter of the cylindrical saddle region is 5 mm to 20 mm, and the maximum diameter of at least one of the first flange structure and the second flange structure, including the inward curl, is 20 mm to 40 mm.

8. The tissue lumen stent according to claim 7, wherein when the body is deployed in tissue, the cylindrical saddle region is measured as the shorter of (a) the length of the body between the portion where the first flange structure is joined to the body and the portion where the second flange structure is joined to the body, and (b) the length of the body which is the shortest distance between any point along the first flange structure and any point along the second flange structure.

9. The tissue lumen stent according to claim 7 or 8, wherein the first flange structure and the second flange structure each include an inward curl at their distal ends, and the first flange structure and the second flange structure are configured to hold tissue walls in parallel.

10. The tissue lumen stent according to any one of claims 7 to 9, wherein the first flange structure has a maximum diameter that is greater than the maximum diameter of the second flange structure in the deployed configuration.

11. The tissue lumen stent according to any one of claims 7 to 10, wherein the outermost opening of at least one of the first flange structure and the second flange structure, which includes the inward curl, has a diameter greater than the maximum diameter of the cylindrical saddle region in the deployed configuration.

12. The tissue lumen stent according to any one of claims 7 to 11, further comprising a cover or membrane covering the cylindrical saddle region, the first flange structure, the second flange structure, or any combination thereof.

13. The tissue lumen stent according to any one of claims 7 to 12, having an overall length of 10 mm to 60 mm in the deployed configuration.

14. A tissue lumen stent comprising a main body having a long, tubular structure and an unfolded structure, When the main body is unfolded into the tissue in the unfolded configuration, the first end and the opposite second end of the main body extend radially into a first flange structure and a second flange structure, respectively, leaving a substantially cylindrical saddle-shaped region between the first flange structure and the second flange structure. At least one of the first flange structure and the second flange structure includes an inward curl at its distal end. A tissue lumen stent in the elongated tubular configuration, wherein the main body has a maximum diameter of 0.8 mm to 4.5 mm, and in the deployed configuration, at least one of the first flange structure and the second flange structure, which include the inward curl, has a maximum diameter of 5 mm to 40 mm.

15. The tissue lumen stent according to claim 14, wherein the first flange structure and the second flange structure each include an inward curl at their distal ends, and the first flange structure and the second flange structure are configured to hold tissue walls in parallel.

16. The distal end, including the inward curl, is bent to reduce trauma to the tissue wall, as described in claim 14 or 15.

17. The tissue lumen stent according to any one of claims 14 to 16, wherein in the deployed configuration, the maximum diameter of the cylindrical saddle region is 5 mm to 20 mm, and at least one of the first flange structure and the second flange structure, which include the inward curl, has a maximum diameter of 20 mm to 40 mm.

18. The tissue lumen stent according to any one of claims 14 to 17, wherein the first flange structure has a maximum diameter greater than the maximum diameter of the second flange structure in the deployed configuration.

19. The tissue lumen stent according to any one of claims 14 to 18, further comprising a covered mesh covering the cylindrical saddle region, and an uncovered mesh on the inwardly curled portion of at least one of the first flange structure and the second flange structure.

20. The tissue lumen stent according to any one of claims 14 to 19, having an overall length of 10 mm to 60 mm in the deployed configuration.

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