PRIORITY

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/903,238, filed September 20, 2019, which is hereby incorporated herein by reference in its entirety as though fully set forth herein.

FIELD

[0002] The presently disclosed subject matter relates to medical stents for biological ducts and vessels. In certain embodiments, the medical stent may be removable.

BACKGROUND

[0003] Medical stents may be placed in a biological vessel to support a weakened or compromised vessel. The vessel may be a blocked passageway that may require a supplementary structure within the vessel to maintain the passageway open for fluid to be transferred within the body. Stents may be used in arteries, bile ducts, and other biological passageways. Conventional stents are often made of a metallic mesh and are often permanently placed with the vessel to be supported. The placement of metallic mesh stents is often permanent because tissue within the vessel may grow over the stent and prevent removal of the stent without traumatic injury to the vessel.

[0004] Conventional stents may be used in an artery, a vein, or another structure such as a ureter. In the case of stents for a biliary obstruction, only patients with a malignant obstruction may be treated with an internal stent under current FDA regulations. Patients with benign biliary strictures have to be treated with either temporary tube drainage or an endoscopically -placed plastic stent that requires frequent changing to prevent the stent from becoming obstructed. To access and change these temporary stents, patients have an open port that compromises quality of life and increases risk of infection.

SUMMARY

[0005] Described herein are internal stents that can support a vessel without obstruction, can remain placed without obstruction until support is no longer needed, and that can be removed from the vessel without damaging the vessel. [0006] In some embodiments, a medical device may comprise a coiled stent comprising a first end, a conduit section, and a second end. In some embodiments, the second end may comprise a retrieval feature. In some embodiments, the coiled stent may be substantially cylindrical in shape and may be configured to be placed within an interior volume of a vessel and exert a radial force upon a wall of the vessel. Optionally, the coiled stent may be configured to be removed from the vessel. In some embodiments, an outer diameter of the coiled stent may be substantially equivalent to an inner diameter of the vessel.

[0007] Also disclosed is a method of expanding or fortifying a vessel, comprising surgically placing a medical device described herein in the vessel. Optionally, the medical device may be expanded using a balloon or other means known to those skilled in the art after the medical device is placed in the vessel. In some embodiments, the method further comprises removing the medical device by attaching an implement to the medical device, the implement being configured to mate with a retrieval feature of the medical device, and pulling the medical device from the vessel.

[0008] Also disclosed is a removal device comprising a metal-tipped sheath and an implement configured to move through the metal-tipped sheath and attach to a retrieval feature of a medical device described herein.

[0009] Also disclosed is a kit comprising a medical device described herein and a removal device comprising a metal-tipped sheath and an implement configured to move through the metal -tipped sheath and attach to a retrieval feature of the medical device.

BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1 is a perspective view of a coiled stent with a hook according to one embodiment described herein.

[0011] FIG. 2 is a perspective view of a coiled stent with a hook according to one embodiment described herein.

[0012] FIG. 3 is a perspective view of a coiled stent with a loop according to one embodiment described herein.

[0013] FIG. 4 is a perspective view of a coiled stent with a loop according to one embodiment described herein. [0014] FIG. 5 is a perspective view of a coiled stent placed in a vessel according to one embodiment described herein.

[0015] FIG. 6 is a perspective view of a coiled stent with varying diameter according to one embodiment described herein.

[0016] FIG. 7 is a perspective view of a removal device with a loop snare according to one embodiment described herein.

[0017] FIG. 8 is a perspective view of a removal device with a hook snare according to one embodiment described herein.

DETAILED DESCRIPTION

[0018] The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying description and drawings, in which some, but not all embodiments of the presently disclosed subject matter are shown. The presently disclosed subject matter can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like numbers refer to like elements throughout. [0019] Many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0020] Described herein are medical stents for biological ducts and vessels. In certain embodiments, the medical stent may be removable. The present disclosure may be embodied in a variety of ways. In one embodiment, the present disclosure may comprise a coiled stent comprising a first end, a conduit section, and a second end. In some embodiments, the second end may comprise a retrieval feature. In some embodiments, the coiled stent may be substantially cylindrical in shape and may be configured to be placed within an interior volume of a vessel and exert a radial force upon a wall of the vessel. Optionally, the coiled stent may be configured to be removed from the vessel. In certain embodiments, the retrieval feature may comprise a loop that extends from the second end of the coiled stent. In certain embodiments, the retrieval feature may comprise a hook that extends from the second end of the coiled stent. Optionally, the stent may be configured to be removed from the vessel by connecting an implement with a complementary design to the retrieval feature and pulling the stent through the vessel to an exit position.

[0021] In some embodiments, an outer diameter of the coiled stent may be substantially equivalent to an inner diameter of the vessel. In some embodiments, the coiled stent may be configured to expand from a first diameter to a second diameter, wherein the first diameter is smaller than the second diameter, and the second diameter is substantially equivalent to an inner diameter of the vessel. Optionally, the stent may comprise expansion joints that become locked or fixed in position upon expansion of the stent to the full diameter. In certain embodiments, the stent may be configured to be expanded by release of tension after placement. In other embodiments, the stent may be configured to be expanded by an auxiliary means such as a balloon. In some embodiments, the stent may be configured to support the vessel and maintain a minimal diameter of the vessel. The diameter of the stent and gauge of the coil may be adjusted to increase or decrease the radial force exerted on the vessel. In some cases, a larger radial force may be needed. In other cases, the vessel walls are generally weak and a lower radial force may be needed.

[0022] In some embodiments, the diameter of the coiled stent may range from about 5 mm to about 15 mm. For example, the diameter of the coiled stent may be about 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, 11.5 mm, 12 mm, 12.5 mm, 13 mm, 13.5 mm, 14 mm, 14.5 mm, or 15 mm. Optionally, the diameter of the first end of the stent may be smaller or larger than the diameter of the second end of the stent. In certain embodiments, the diameter of the stent may increase from a first end throughout the conduit section. In other embodiments, the diameter of the stent may decrease from a first end throughout the conduit section. For example, the diameter of the first end may be about 5 mm and the diameter of the second end may be about 10 mm, with diameter of the conduit section increasing from 5 mm near the first end to about 10 mm near the second end.

[0023] In some embodiments, the coiled stent may comprise a metal. For example, the coiled stent may comprise stainless steel, a cobalt chrome alloy, a nickel aluminum alloy, or a nickel titanium alloy, such as Nitinol (available from Memry Corporation, Bethel, CT), or other metal alloy known to those skilled in the art. Optionally, the coiled stent may be comprised of a metal alloy coated with a polymer. In certain embodiments, the polymer may be a Polytetrafluoroethylene (PTFE) or GORE-TEX (available from W.L. Gore, Flagstaff, AZ).

[0024] In certain embodiments, the coiled stent may be resistant to tissue incorporation.

The lack of incorporation may enable the coiled stent to be removed from the vessel after a prolonged period of placement. Optionally, the coiled stent may be coated with a pharmaceutical composition that may be released from the stent upon placement in the vessel. For example, the coiled stent may be coated with a pharmaceutical composition to impede tissue incorporation, such as Paclitaxel.

[0025] The cross-section of the coil used for the stent may differ based on application. In some embodiments, the cross section may be substantially circular with a smooth profile. In other embodiments, the cross section may be hexagonal, or irregular in shape. An irregular shape, or non-circular shape, may aid in the removal of the stent by minimizing the points of contact with the vessel.

[0026] Turning to the figures, FIGS. 1 and 2 show a coiled stent 100 with a hook 120, 140 attached to the coil 110. The hook 120 may be oriented toward the center of the coil 110 as in FIG. 1 or the hook 140 may be oriented away from the coil 110 as in FIG. 2. FIGS. 3 and 4 show a coiled stent 100 with a loop 130, 150 attached to the coil 110. The loop 130 may extend from the coil 110 as in FIG. 3 or the loop 150 may be located at the end of the coil 110 and aligned with the coil 110 as in FIG. 4.

[0027] FIG. 5 shows a coiled stent in a vessel 160, where the vessel tissue 140 has grown around a portion of the coil 110, and hook 120 remains accessible.

[0028] FIG. 6 shows a coiled stent 100, where the diameter of the coil 110 changes over the length of the coiled stent 100. Diameter dl of the coil 110 is smaller than diameter d2 of the coil 110 at the retrieval end of the coiled stent 100. In some embodiments, the retrieval end may be located at smaller end of the coiled stent 100.

[0029] As used herein, a vessel may comprise a duct, a canal, a stricture, or other biological passage.

[0030] In other embodiments, the present disclosure comprises a method of expanding or fortifying a vessel, the method may comprise surgically placing a coiled stent described herein in the vessel. Optionally, the coiled stent may be configured to expand after being placed in the vessel. In certain embodiments, the coiled stent may be expanded using a balloon or other means known to those skilled in the art after the coiled stent is placed in the vessel. In some embodiments, the method further comprises removing the coiled stent by attaching an implement configured to mate with the retrieval feature of the coiled stent to the retrieval feature and pulling the coiled stent from the vessel.

[0031] The coiled stent may be placed in a variety of vessels. The method for placement may be dependent on the location of the vessel. In some embodiments, the coiled stent may be placed in the vessel endoscopically. In some embodiments, the coiled stent may be placed in the vessel percutaneously.

[0032] In some embodiments, the present disclosure comprises a removal device comprising a metal-tipped sheath and an implement configured to move through the metal- tipped sheath and attach to the retrieval feature of a medical device described herein. As shown in FIGS. 7 and 8, the retrieval device 200 may include a looped snare 210 or a hooked snare 230 that can form a secure connection to a hook or a loop retrieval end of a coiled stent, as described herein.

[0033] In other embodiments, the present disclosure comprises a kit comprising a medical device described herein, and a removal device comprising a metal-tipped sheath and an implement configured to move through the metal-tipped sheath and attach to the retrieval feature of the medical device.

[0034] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Additionally, any reference referred to as being “incorporated herein” is to be understood as being incorporated in its entirety.

[0035] The terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “a coil” includes a plurality of such coils, unless the context clearly is to the contrary (e.g., a plurality of coils), and so forth.

[0036] Various embodiments of the disclosure have been described herein. It should be recognized that these embodiments are merely illustrative of the present disclosure.

Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. It is expected that skilled artisans can employ such variations as appropriate, and the disclosure is intended to be practiced otherwise than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated or otherwise clearly contradicted by context.

Illustrative embodiments

[0037] As used below, any reference to medical devices, methods, or kits is to understood as a reference to each of the those medical devices, methods, or kits disjunctively (e.g., “Illustrative embodiments 1-4 is to be understood as illustrative embodiment 1, 2, 3, or 4”). [0038] Illustrative embodiment 1 is a medical device comprising a coiled stent comprising a first end, a conduit section, and a second end, wherein the second end comprises a retrieval feature, wherein the coiled stent is substantially cylindrical in shape and is configured to be placed within an interior volume of a vessel and exert a radial force upon a wall of the vessel, and wherein the coiled stent is configured to be removed from the vessel.

[0039] Illustrative embodiment 2 is the medical device of any preceding or subsequent illustrative embodiment, wherein the retrieval feature comprises a hook that extends from the second end of the coiled stent.

[0040] Illustrative embodiment 3 is the medical device of any preceding or subsequent illustrative embodiment, wherein the retrieval feature comprises a loop that extends from the second end of the coiled stent.

[0041] Illustrative embodiment 4 is the medical device of any preceding or subsequent illustrative embodiment, wherein an outer diameter of the coiled stent is substantially equivalent to an inner diameter of the vessel. [0042] Illustrative embodiment 5 is the medical device of any preceding or subsequent illustrative embodiment, wherein the coiled stent is configured to expand from a first diameter to a second diameter, wherein the first diameter is smaller than the second diameter, and the second diameter is substantially equivalent to an inner diameter of the vessel.

[0043] Illustrative embodiment 6 is the medical device of any preceding or subsequent illustrative embodiment, wherein the coiled stent is configured to support the vessel and maintain a minimal diameter of the vessel.

[0044] Illustrative embodiment 7 is the medical device of any preceding or subsequent illustrative embodiment, wherein the coiled stent comprises a metal alloy.

[0045] Illustrative embodiment 8 is the medical device of any preceding or subsequent illustrative embodiment, wherein the coiled stent comprises stainless steel, a cobalt chrome alloy, a nickel aluminum alloy, or a nickel titanium alloy.

[0046] Illustrative embodiment 9 is the medical device of any preceding or subsequent illustrative embodiment, wherein the metal alloy is coated with a polymer.

[0047] Illustrative embodiment 10 is the medical device of any preceding or subsequent illustrative embodiment, wherein the coiled stent is resistant to tissue incorporation.

[0048] Illustrative embodiment 11 is the medical device of any preceding or subsequent illustrative embodiment, wherein stent has a circular cross section.

[0049] Illustrative embodiment 12 is the medical device of any preceding or subsequent illustrative embodiment, wherein stent has a non-circular cross section.

[0050] Illustrative embodiment 13 is the medical device of any preceding or subsequent illustrative embodiment, wherein the vessel comprises at least one of a duct, a canal, a stricture, or other biological passage.

[0051] Illustrative embodiment 14 is a method for expanding or fortifying a vessel, comprising surgically placing the medical device of any one of illustrative embodiments 1- 13 in the vessel.

[0052] Illustrative embodiment 15 is the method of any preceding or subsequent illustrative embodiment, further comprising expanding the medical device using a balloon after the medical device is placed in the vessel.

[0053] Illustrative embodiment 16 is the method of any preceding or subsequent illustrative embodiment, wherein the medical device is configured to expand after being placed in the vessel. [0054] Illustrative embodiment 17 is the method of any preceding or subsequent illustrative embodiment, wherein the medical device is placed endoscopically.

[0055] Illustrative embodiment 18 is the method of any preceding or subsequent illustrative embodiment, wherein the medical device is placed percutaneously.

[0056] Illustrative embodiment 19 is the method of any preceding or subsequent illustrative embodiment, further comprising removing the medical device from the vessel.

[0057] Illustrative embodiment 20 is the method of any preceding or subsequent illustrative embodiment, wherein removing the medical device comprises attaching an implement configured to mate with the retrieval feature of the medical device to the medical device and pulling the medical device from the vessel.

[0058] Illustrative embodiment 21 is a removal device comprising a metal-tipped sheath and an implement configured to move through the metal-tipped sheath and attach to the retrieval feature of the medical device of any one of illustrative embodiments 1-13.

[0059] Illustrative embodiment 22 is a kit comprising the medical device of any one of illustrative embodiments 1-13 and a removal device comprising a metal -tipped sheath and an implement configured to move through the metal-tipped sheath and attach to the retrieval feature of the medical device.