Urinary tract stent

Abstract

The present invention relates to a stent for insertion into a lumen of an anatomical blood vessel or conduit, comprising a helical coil embedded in a sub-polymer tube and comprising an expandable portion.

Description

Technical Field

[0001] The present disclosure relates to a stent for insertion into the lumen of an anatomical vessel or duct, the stent comprising an expandable portion capable of being in a compressed configuration during insertion and in an expanded configuration after having been placed in the vessel or duct. Background Art

[0002] Stents are commonly used to maintain or create lumens in body cavities. Stents are usually formed as tubular endoluminal prostheses and placed in blood vessels or ducts of humans or animals. Stents can be used in various body cavities where body cavity obstruction may occur, such as the urethra, blood vessels, etc.

[0003] After the stent is implanted, it is necessary to keep it in place. Therefore, in order to ensure a secure anchoring of the stent in the body cavity, an anchoring component needs to be provided. Known stents can be anchored at a desired position in the body cavity by expanding at least a portion of the stent after insertion. However, stent displacement is often observed: for example, an intraprostatic urethral stent located between the external urethral sphincter and the bladder neck may be displaced all the way into the bladder.

[0004] Additionally, the mechanical flexibility of the stent should be balanced to support the anatomy of the body lumen into which the stent is inserted and to follow the physical properties of the body lumen, thereby providing overall flexibility to provide a higher quality of life in terms of physiological anatomical function.

[0005] U.S. Patent Application US2003 / 040803 discloses a urethral stent comprising a helical coil comprising a series of continuous turns made from a single wire. The diameter of the stent can be adjusted by twisting the helical coil, which restores its diameter after the torsional stress is released. The stent also includes a soft webbing. This stent requires a complex insertion kit to enable the torsion of the stent to be maintained during placement. In addition, this stent is easily compressed under radial pressure, in a similar manner to when it is twisted. Finally, the soft webbing may fold into folds (especially when the diameter of the stent is reduced), which can restrict the flow of urine and / or create a stagnant point of urine by restricting the inner diameter of the stent, thereby causing infection.

[0006] US patent application US2009 / 210045 discloses urethral stents based on shape memory materials. However, these stents are prone to tissue scaling between the turns of the wire and do not ensure a tight barrier between the inside and outside of the stent. Furthermore, the shape of the stent is ensured by a very compact structure in which the successive turns of the wire are in contact, resulting in an uncomfortable device that cannot be bent and conform to the anatomical structure of the tract.

[0007] The stents disclosed herein provide balanced performance in terms of retention capacity, strong anchoring, and overall flexibility, thereby overcoming some or all of the disadvantages of the prior art. Summary of the invention

[0008] Thus, the present disclosure relates to a stent comprising a polymer tube and a single wire forming a helical coil, the hollow portion of the polymer tube defining a longitudinal axis (Oz). The stent is intended to be inserted into the lumen of an anatomical vessel or duct, preferably a urinary tract vessel or duct. The helical coil comprises:

[0009] i. a series of continuous wire turns embedded in a polymer tube; and

[0010] ii. At least one expandable portion capable of being in a compressed configuration or an expanded configuration, the expandable portion being a shape memory material.

[0011] Furthermore, the axis of the helical coil is substantially parallel to the longitudinal axis (Oz); and the polymer tube is radially rigid to prevent a reduction in diameter of the turns embedded in the polymer tube when the stent is twisted about the longitudinal axis (Oz).

[0012] In other words, the wire is wound in the wall of the polymer tube. The polymer tube thus obtained is very rigid in the radial direction: it does not collapse when pressure is applied radially (i.e., when pressure is applied in a direction perpendicular to the longitudinal axis (Oz)) or when the wire is twisted. But the polymer tube remains flexible in the axial direction: the polymer tube is able to bend to conform to the shape of the lumen in which it is inserted. The stent is therefore a composite device in which the polymer tube and the wire work together to obtain the desired mechanical properties: radial rigidity to resist compression due to natural movements or stenosis and at the same time flexibility. This flexibility is highly desirable for patient comfort. For example, in urological applications, the shape of the urethra changes depending on the patient's activities (sitting / standing, cycling, sexual relations), and the stent 10 should adapt to these shape changes.

[0013] It is noteworthy that the continuous turns are embedded in the polymer tube and the configuration of the continuous turns cannot be changed from a compressed state to an expanded state. Therefore, the continuous turns and the expandable portion are different parts of the helical coil.

[0014] In embodiments, at least one expandable portion is located at the distal end of the stent or at the proximal end of the stent.

[0015] In embodiments, at least one expandable portion protrudes forward of the distal end of the polymeric tube or protrudes forward of the proximal end of the polymeric tube.

[0016] In an embodiment, at least one expandable portion comprises a series of continuous turns.

[0017] In an embodiment, at least one expandable portion comprises a series of continuous turns of wire wound around a polymer tube in a compressed configuration.

[0018] In an embodiment, the inner surface of the polymer tube is cylindrical, preferably, the inner surface of the polymer tube is cylindrical and smooth. In an embodiment, the outer surface of the polymer tube is partially or completely corrugated. In a preferred embodiment, the inner surface of the polymer tube is cylindrical and smooth, and the outer surface of the polymer tube is partially corrugated.

[0019] In an embodiment, the continuous turns of the helical coil embedded in the polymer tube have a constant pitch. Alternatively, the continuous turns of the helical coil embedded in the polymer tube have a first constant pitch in a first portion of the polymer tube and a second constant pitch in a second portion of the polymer tube, the second constant pitch being different from the first constant pitch.

[0020] In an embodiment, the helical coil comprises at least one expandable portion comprising a pair of turns facing in opposite directions and closed in a U-shape, such that the at least one expandable portion defines a cylinder in its expanded configuration. In particular, the helical coil may comprise two U-shaped expandable portions, the second expandable portion comprising a pair of turns facing in opposite directions and closed in a U-shape, such that the second expandable portion defines a cylinder in its expanded configuration.

[0021] In an embodiment, the at least one expandable portion comprises a series of continuous turns in the compressed configuration and defines a conical shape in its expanded configuration.

[0022] In an embodiment, at least one expandable portion is coated with a polymer.

[0023] In an embodiment, the shape memory material is selected from a polymer or a metal alloy. Preferably, the shape memory material is a metal alloy of nickel and titanium.

[0024] The present disclosure also relates to a kit comprising:

[0025] - a stent as disclosed above;

[0026] - Introduction tools for introduction, deployment and manipulation of stents; and

[0027] - Flushing channels, which direct fluid through the introducer tool to the stent.

[0028] definition

[0029] In the present invention, the following terms have the following meanings:

[0030] "Distal end" refers to the portion of the stent that is located close to the orifice through which the stent is introduced, ie, close to the external opening of the reproductive system.

[0031] "Expandable" refers to a portion of a stent whose size is capable of increasing from a compressed state to an expanded state. Expansion is triggered by an external stimulus such as a change in temperature (thermal activation) or a mechanical constraint (mechanical activation).

[0032] "Flexibility" refers to a general mechanical property and is not precisely measured in this disclosure. Flexibility must be understood as the property of the stent to bend or follow the patient's movements in terms of anatomical paths and physiological anatomical functions. A flexible stent should not form wrinkles, which can be uncomfortable and restrict fluid flow.

[0033] "French / Charrière", abbreviated Fr, refers to the scale of catheter diameters: 1 mm equals 3 Fr. Therefore, the diameter of a round catheter in millimeters can be calculated by dividing the French size by 3. Charrière is equivalent to French.

[0034] A "helical coil" refers to a continuous series of turns of a wire, the turns (or spiral) being more or less regularly spaced, the turns being oriented approximately along the same axis, and the turns having approximately the same diameter. Since a helical coil is deformable, its exact geometry is not well defined. In particular, a helical coil may be bent, stretched or compressed.

[0035] "Pitch" refers to the repeat length between two consecutive turns of a helical coil having regularly spaced turns.

[0036] "Proximal" refers to the portion of the stent located distal to the orifice through which the stent is introduced, ie, distal to the external opening of the reproductive system. DETAILED DESCRIPTION

[0037] The present disclosure relates to a stent 10 for insertion into the lumen of an anatomical vessel or duct. The stent 10 includes a polymer tube 30 and a single wire 20 forming a helical coil, the hollow portion of the polymer tube 30 defining a longitudinal axis (Oz). The helical coil includes a series of continuous turns embedded therein. The axis of the helical coil is the direction in which the turns are wound around it. The axis of the helical coil is substantially parallel to the longitudinal axis (Oz). The polymer tube 30 is intended to maintain and support the lumen of the lumen into which the stent 10 is inserted: the polymer tube 30 is radially rigid to prevent the diameter of the turns embedded in the polymer tube 30 from decreasing when the stent is twisted around the longitudinal axis (Oz). In addition, the polymer tube 30 remains flexible in the axial direction: the polymer tube 30 can be bent to conform to the shape of the lumen into which the polymer tube 30 is inserted. In addition, the helical coil includes an expandable portion 22, which can be in a compressed configuration or an expanded configuration. The expandable portion 22 is made of a shape memory material. Therefore, the stent 10 can be inserted and placed with the expandable portion 22 compressed in a small diameter shape. After placement, the shape memory material can be triggered to adopt its expanded configuration. In the expanded region, the stent 10 applies a radial load on the wall of the lumen and is anchored. Finally, the shape memory material can be triggered again to lose its shape to remove the stent 10. For example, the expandable portion 22 can be designed to have a first shape at room temperature (for introduction), have a first trigger at a high temperature (about 45°C or slightly above 45°C) to expand and remain in an expanded state at body temperature; and have a second trigger at a low temperature (about 15°C or slightly below 15°C), at which the expandable portion 22 loses its mechanical properties and softens for removal. In fact, softening the wire 20 simplifies stent removal because the expandable portion 22 no longer applies pressure and the wire 20 can be deformed into a slender wire instead of a large diameter coil.

[0038] In the present disclosure, the continuous turns are embedded in the polymer tube 30, and their configuration cannot be changed from a compressed state to an expanded state. Therefore, the continuous turns and the expandable portion 22 are different parts of the helical coil.

[0039] The stent 10 disclosed herein is particularly suitable for urological applications and may be placed in the ureter, bladder neck, or urethra.

[0040] In the present disclosure, a single wire 20 is used. A single wire means that the entire coil is made of one wire, but the single wire 20 can be arranged to move back and forth along the longitudinal axis (Oz) of the polymer tube 30, for example to form an interwoven spiral. A single wire 20 is advantageous when the stent 10 must be removed. In fact, the practitioner can pull the wire 20 to move the stent 10. Since the wire 20 is at least partially embedded in the polymer tube 30, the polymer tube 30 will be pulled at the same time. In addition, the portion of the wire 20 embedded in the polymer tube 30 will not stretch, and the total length of the stent 10 to be removed is reduced. Finally, since the wire 20 is a single element, the risk of breakage during the removal process is greatly reduced.

[0041] The polymer tube 30 can be any suitable polymer known in the art. The polymer tube 30 can include additives to adapt the surface properties: the polymer tube 30 can be hydrophilic and / or hydrophobic to improve accelerated urine flow, reduce scaling and infection, and provide a strong anchoring force. The polymer tube 30 can have tissue biocompatibility and magnetic resonance imaging biocompatibility functions. The polymer tube 30 can be plasma treated. The polymer tube 30 can also contain drugs or active substances, which will be slowly released in the tissue inserted with the stent 10, thereby providing therapeutic treatment.

[0042] Suitable polymers are, for example, thermoplastic polyurethane (TPU) and silicone.

[0043] The outer diameter of the polymer tube 30 may be selected from 8 Fr / CH to 26 Fr / CH. Particularly suitable outer diameters are 10.6 Fr / CH, 24 Fr / CH.

[0044] The expandable portion 22 may be located anywhere along the polymeric tube 30 .

[0045] In an embodiment, the expandable portion 22 is located at the end (distal or proximal end) of the stent 10, or elsewhere, to maintain a strong anchoring force corresponding to the associated pathology while taking into account physiological and anatomical constraints and characteristics. If the stent 10 includes two expandable portions 22, the two expandable portions 22 can be located at both ends of the stent 10 (distal and proximal ends), or at one end and the central portion of the stent 10. For example, the expandable proximal portion anchored at the level of the bladder neck and within the bladder is specifically designed to enhance the flow of urine to the urethra and avoid any residual volume during urination. In the intra-prostatic urethra region, the expandable distal portion anchored above the external sphincter at the bottom of the prostate is specifically designed to prevent the risk of displacement and retrograde ejaculation. All expandable portions 22 are specifically designed to facilitate the insertion, expansion and removal of the stent 10.

[0046] In an embodiment, the expandable portion 22 protrudes in front of the distal end of the polymer tube 30 or in front of the proximal end of the polymer tube 30. This is advantageous when the polymer tube 30 is intended to maintain and support the lumen of the cavity and the expandable portion 22 is anchored in a stronger and healthier area, which has different tissue resistance than the cavity where the polymer tube 30 is located. In particular, the expandable portion 22 may include a series of continuous turns. For example, the spiral coil may be partially embedded in the polymer tube 30 (the retaining portion) and partially protrude from the polymer tube 30 (the expandable portion 22). If the stent 10 includes two expandable portions 22, the two expandable portions 22 may be located at both ends of the stent 10 (the distal end and the proximal end), or at one end and the central portion of the stent 10. Figures 4 to 5 is an illustration of a stent 10 with two expandable portions 22 protruding at both ends of a polymer tube 30. In urological applications, the configuration in which the expandable portions 22 protrude in front of the distal end of the polymer tube 30 is particularly advantageous for the drainage of urine: the continuous turns of the distal end of the stent 10 help to drain the liquid towards the polymer tube 30 and avoid any accumulation of urine that could cause scaling and infection. In another urological application, the configuration in which the expandable portions 22 protrude in front of the proximal end of the polymer tube 30 is particularly advantageous for allowing the fluid to flow between the urethra and the ducts that reach the urethra, such as the ejaculatory ducts. In fact, in order to avoid retrograde ejaculation, the stent 10 should not block the flow of sperm into the urethra: the open structure of the expandable portions 22 is therefore suitable for keeping the urethra open without closing the ducts.

[0047] Alternatively, the expandable portion 22 includes a series of continuous turns wrapped around the polymer tube 30 in a compressed configuration to ensure uniform inner and outer diameters of the insertion system and the stent 10. This will allow accurate optical visualization and ease of insertion through the urinary tract, thereby avoiding the need for expansion prior to insertion. The expandable portion 22 can be located at the end (distal or proximal end) of the stent 10, or at other locations. If the stent 10 includes two expandable portions 22, the two expandable portions 22 can be located at both ends of the stent 10 (distal and proximal ends), or at one end and a central portion of the stent 10. Figure 1 to Figure 2 is an illustration of a stent 10 having an expandable portion 22 at one end of a polymeric tube 30.

[0048] In the present disclosure, the polymer tube 30 includes at least one hollow portion (sometimes referred to as a lumen in the field of stents) through which a liquid can flow or a surgical instrument can be displaced. The hollow portion defines a longitudinal axis (Oz). The helical coil is embedded in the wall of the polymer tube 30 so that the hollow portion is located in the inner portion of the helical coil: the helical coil is substantially parallel to the longitudinal axis (Oz).

[0049] Obviously, the diameter of the turns of the helical coil embedded in the polymer tube 30 is larger than the inner diameter of the polymer tube 30 .

[0050] The inner diameter of the polymer tube 30 may be selected from 6 Fr / CH to 24 Fr / CH. Particularly suitable inner diameters are 7 Fr / CH and 18 Fr / CH.

[0051] The thickness of the polymer tube 30 may be selected from 0.2 mm to 1.4 mm, preferably 0.2 mm to 0.66 mm.

[0052] Obviously, the diameter of the turns of the helical coil embedded in the polymer tube 30 is defined by the diameter of the polymer tube 30. Also, the thickness of the polymer tube 30 is greater than the diameter of the wire 20 embedded in the polymer tube 30.

[0053] In an embodiment, the inner surface of the polymer tube 30 is cylindrical, preferably with a smooth surface. In another embodiment, the outer surface of the polymer tube 30 is corrugated over a portion of the polymer tube 30 or over the entire polymer tube 30 .

[0054] The surface shape has several advantages. The cylindrical smooth inner surface provides the highest flow rate for a given cross section; therefore, the liquid flow is not affected. In addition, the cylindrical smooth inner surface limits scaling, thereby avoiding the accumulation of mineral salts and crystalline deposits, such as from urine, in the stent 10, which may lead to blockages, which in turn lead to infections caused by urine stagnation. The corrugated outer surface has a better contact with the cavity wall to be maintained and avoids the movement of the stent 10. Therefore, this corrugated outer surface limits the movement of the stent 10 and helps to anchor firmly.

[0055] In a preferred embodiment, the inner surface of the polymer tube 30 is hydrophilic (eg, to improve accelerated urine flow and reduce scaling), while the outer surface is hydrophobic (eg, to prevent urine from flowing between the stent 10 and tissue and provide a secure anchoring force).

[0056] In a preferred embodiment, the corrugated outer surface of the polymer tube 30 is defined corresponding to the turns of the helical coil embedded in the polymer tube 30: in the outer surface, peaks appear at the locations of the wire 20, and in the outer surface, valleys appear between two consecutive turns of the wire 20.

[0057] In the present disclosure, the flexibility of the stent 10 (the ability to bend along the longitudinal axis of the polymer tube 30) is derived from the inherent mechanical properties of the polymer tube 30 (material, thickness, ...) and the inherent mechanical properties of the wire 20 (material, diameter, ...) and the geometry of the wire 20 embedded in the polymer tube 30, thereby forming a composite device. Obviously, if the consecutive turns of the helical coil embedded in the polymer tube 30 are in contact, the helical coil will not be able to bend easily, resulting in low flexibility of the stent 10. On the contrary, if the consecutive turns are well spaced by the flexible polymer, the bending will be determined by the polymer properties and the stent 10 may be very flexible. The geometry of the wire 20 embedded in the polymer tube 30 allows the design of the stent 10 to conform to the associated pathology, with variable degrees of flexibility for physiological anatomical properties (such as peristaltic movement of the ureter) and associated pathologies (such as but not limited to stenosis, external pressure from adjacent organs, ...). The flexibility of the stent 10 can include deformation of the polymer tube 30 (basically bending or peristaltic fluctuations). However, the polymer tube 30 is radially rigid. In particular, the stent 10 can be used to combat strictures: if the tract is closed (or nearly closed), the stent 10 will create an open channel through the polymer tube 30, and the mechanical properties of the polymer tube 30 reinforced with the wire 20 ensure that the channel remains open. This is particularly important in the case of urine drainage. During urination, the flow of urine is controlled by the balance between the bladder pressure and the urethral opening. In the event of stricture, urine will be retained in the bladder, which may lead to complications such as infection or kidney stones. Keeping the channel of the stent 10 open will avoid urine retention in the bladder. The polymer tube 30 with an inner diameter of 18 Fr / CH is particularly suitable for this situation.

[0058] In an embodiment, the successive turns of the helical coil embedded in the polymer tube 30 have a constant pitch. In this embodiment, the flexibility of the stent 10 will be uniform. This embodiment is suitable when it is expected that the retention structure will apply a uniform load on the wall of the lumen into which the retention structure is inserted, without low pressure points that may cause patient discomfort or fatigue cracking of the stent 10.

[0059] In another embodiment, the continuous turns of the helical coil embedded in the polymer tube 30 have a first constant pitch in a first portion of the polymer tube 30 and a second constant pitch in a second portion of the polymer tube 30, the second constant pitch being different from the first constant pitch. This embodiment defines two regions with different flexibility along the stent 10. This embodiment is particularly advantageous when the stent 10 must support the cavity wall on one portion and follow the patient's movements according to physiological and anatomical characteristics on another portion.

[0060] More generally, the helical coil may define more than two sections, each section having a constant pitch. The pitch of the helical coil may also vary according to a predefined design, thereby providing "on-demand" flexibility along the stent 10.

[0061] In an embodiment, the expandable portion 22 comprises a pair of turns facing in opposite directions and closed in a U-shape. In the expanded configuration of the expandable portion 22, the expandable portion 22 thus adopts a cylindrical shape defined by two circles corresponding to the two expanded turns, hereinafter referred to as a U-shaped geometry. This cylindrical shape is particularly advantageous for applying a load on a large surface in contact with the cavity wall to avoid movement of the wire 20 and provide better anchoring over a large area.

[0062] The U-shaped expandable portion 22 also allows in some cases for liquid to flow out of the polymer tube 30. In fact, anchoring is ensured by simple wires 20 that do not block possible flow paths between the outer surface of the stent 10 and the tissue. This is particularly important for a prostate stent 10 that should not induce retrograde ejaculation.

[0063] For the U-shaped geometry, the outer diameter of the expandable portion 22 in its compressed configuration can be selected from 8 Fr / CH to 26 Fr / CH. Particularly suitable outer diameters are 10.6 Fr / CH, 24 Fr / CH. After expansion, the diameter of the expandable portion 22 can be selected from 18 Fr / CH to 44 Fr / CH. Typically, the outer diameter in the expanded configuration is 1.5 to 2 times larger than the outer diameter in the compressed configuration. The preferred pairing of diameters in the compressed and expanded configurations is 10.6 / 21 Fr / CH, 24 / 42 Fr / CH.

[0064] In an embodiment, the cylinder defined by the two expanded turns and the polymer tube 30 are coaxial.

[0065] Alternatively, the cylinder defined by the two expanded turns may not be coaxial with the polymer tube 30. In this particular configuration, the stent 10 can be placed in a lumen while maintaining a lumen between the stent 10 and the lumen wall. If the polymer tube 30 is not a tube (such as in the case of drainage), this configuration allows liquid to flow on the outer surface of the polymer tube 30. If the polymer tube 30 is a tube, this configuration allows two different flow paths: inside the tube and outside the tube, which is particularly useful when the stent 10 is placed at the junction of two blood vessels or pipes.

[0066] In an embodiment, the helical coil comprises two or more expandable portions 22, each expandable portion 22 comprising a pair of turns facing in opposite directions and closed in a U-shape, as described above. In this embodiment, the stent 10 is anchored to the cavity on two or more cylindrical regions. Therefore, each anchoring point applies a lower load to the cavity wall, but all anchoring points together provide a firm anchoring. In addition, the two U-shaped expandable portions 22 define the precise position of the stent 10 and avoid any movement or displacement of the stent 10. It also allows the precise structure of the turns of the helical coil to be maintained: the more or less flexible parts of the stent 10 are therefore precisely positioned. Each U-shaped expandable portion 22 can be coaxial with the polymer tube 30, or it can be non-coaxial with the polymer tube 30.

[0067] In an embodiment, the expandable portion 22 comprises a series of continuous turns in the compressed configuration and defines a conical shape (hereinafter referred to as a conical geometry) in its expanded configuration. This conical shape is particularly advantageous when a pipe or blood vessel is connected to a larger cavity. The conical shape can be expanded in a large cavity, thereby preventing the stent 10 from being displaced into the blood vessel or pipe.

[0068] For a conical geometry, the outer diameter of the expandable portion 22 in its compressed configuration can be selected from 8 Fr / CH to 24 Fr / CH. Particularly suitable outer diameters are 10.6 Fr / CH, 24 Fr / CH. After expansion, the outer diameter of the largest turn of the expandable portion 22 can be selected from 18 Fr / CH to 44 Fr / CH. Typically, the diameter of the largest turn in the expanded configuration is 1.5 to 2 times larger than the diameter in the compressed configuration. The preferred pairing of the diameter in the compressed configuration and the largest turn in the expanded configuration is 10.6 / 21 Fr / CH, 24 / 42 Fr / CH.

[0069] More generally, the stent 10 of the present disclosure may have several expandable portions 22 selected from a cylindrical geometry, a U-shaped geometry, or a conical geometry.

[0070] For example, the stent 10 according to the present disclosure may include

[0071] • A U-shaped geometry at the distal end of the stent and another U-shaped geometry at the proximal end or middle of the stent;

[0072] • U-shaped geometry at the distal end and conical geometry at the proximal end;

[0073] • U-shaped geometry at the proximal end and conical geometry at the distal end; or

[0074] • Conical geometry at the distal end and another conical geometry at the proximal end.

[0075] In all of these examples, the cylindrical, U-shaped, and conical geometries may protrude from or may be wrapped around the polymer tube 30 .

[0076] In an embodiment, the helical coil is formed from a single wire 20, but includes a loop 26, preferably at the distal end of the stent 10. In this embodiment, the wire 20 is bent to form a loop 26 at one end of the stent 10. Such a loop 26 provides several advantages. Firstly, the free end 24 of the wire 20 is not cut sharply, which avoids any risk of the wire 20 causing tissue damage or sensitive and uncomfortable points in the tissue. Secondly, the loop 26 is a practical point to grasp the stent 10 for easy removal: in fact, during operation, a simple hook can be used to enter the loop 26 and enable easy traction on the wire 20 to facilitate the removal of the stent 10. This feature is particularly useful in Figure 7 Third, the wire 20 is bent and its apparent length is shorter. In other words, after the helical coil is extended, the length of the wire 20 with the loop 26 (from the loop 26 to the free end 24 of the single wire 20) may be half the length of the same wire 20 without the loop 26. During stent removal, the shorter length is desirable for patient comfort and ease of operation. This feature is shown in Figures 6 and Figures 10 to 12 It is clearly visible that the U-shaped distal end is actually a loop. The helical coil in the polymer tube 30 is an interweaving of two helices.

[0077] When the ends of the stent 10 are in a U-shaped geometry with loops 26, the expanded configuration may include two pairs of turns facing in opposite directions and closed in a U-shape, as shown in FIGS. Figures 10 to 12 , to provide better anchoring. In fact, the two U-shaped parts face each other and form two reinforcements for the same part of the stent 10. This structure is not squeezed, thus providing a more stable anchoring effect and placement. Finally, the height of this expandable part 22, measured along the longitudinal axis (Oz), does not change significantly during expansion: after placing the stent 10 in the compressed configuration, the expandable part 22 expands and remains in the exact placement position. Therefore, the accuracy of placement is improved. The expandable part 22 with an expanded diameter of 42 Fr / CH is particularly suitable in this case.

[0078] In an embodiment, the helical coil is formed from a single wire 20 but includes two loops 26: one loop 26 at the distal end of the stent 10 and one loop 26 at the proximal end of the stent 10. The loop 26 at the proximal end of the stent 10 may facilitate manipulation and precise placement of the stent 10.

[0079] Conical geometries may have additional features.

[0080] In the embodiment shown in Figure 6, at the distal end, the conical geometry of the expansion portion forms a conduit with a continuous wall. In this geometry, the expandable portion 22 expands so that the spirals contract and are in contact along the axis of the spiral coil, and there is no space between the spirals. This geometry provides a sealing effect and prevents liquid from flowing through the spiral coil and tissue proliferation. This effect is further enhanced when the expandable portion 22 of the stent 10 is coated with a polymer, which ultimately has hydrophobic / hydrophilic and / or compressible properties to provide a sealing effect. This feature is particularly attractive at the proximal end of the stent to avoid liquid dispersion around the stent and ultimately lead to liquid retention, which should be prevented to avoid potential infection around the stent.

[0081] Alternatively, the conical geometry of the expansion section forms a duct with well-separated spirals at the proximal end, e.g. Figure 7 As shown. In this geometry, the expansion portion behaves like a drain to help the fluid flow in the direction of the polymer tube. This feature is particularly attractive at the proximal end of the stent to avoid any fluid accumulation. For example, if the conical expansion portion is placed in the bladder (just above the bladder neck), the drainage of urine will be completed. Preferably, the conical expansion portion protrudes in front of the distal end of the polymer tube 30.

[0082] In an embodiment, the expandable portion 22 is coated with a polymer. In particular, the expandable portion 22 can be coated with the same polymer as used for the polymer tube 30, eventually including additives. Preferably, the coating thickness is below 300 μm, so that the mechanical properties of the coating are negligible and do not impair the expansion or compression of the expandable portion 22.

[0083] Regarding shape memory materials, polymers and metal alloys are suitable. The polymer shape memory material can be selected from polyurethane, polynorbornene or cross-linked polyethylene oxide (PEO)-polyethylene terephthalate (PET) block copolymer. The metal alloy shape memory material can be selected from copper-aluminum-nickel and nickel-titanium. The metal alloy of nickel and titanium (generally known as Nitinol) is particularly suitable.

[0084] The preferred shape memory material is selected from heat-activated shape memory materials. In particular, when the shape memory material is formed at room temperature and maintains its stress structure until the normal internal temperature of the human body (up to 40°C), it is best to use it in the human body. After the stent 10 is placed, the stent can be thermally expanded using a heated liquid that can be circulated around the stent 10, the temperature of which is higher than 40°C but low enough to avoid any damage, thereby inducing the expansion of the expandable portion 22. The preferred transition temperature of the shape memory material is between 45°C and 65°C.

[0085] Other suitable shape memory materials are selected from mechanically activated shape memory materials. In this case, the stent 10 is placed in the human body and then mechanically stimulated (eg, by force, torsion or vibration) to release internal stress and trigger the shape change.

[0086] In an embodiment, the expansion is irreversible: after expansion using heated fluids or mechanical restraint, the stent 10 retains its expanded configuration.

[0087] The stent 10 disclosed above can be easily removed from the body. After cooling, typically below 15°C, the shape memory material loses its rigidity, becomes elastic, and can be deformed with little force. Therefore, a practitioner can remove the stent by cooling the stent 10 according to the present invention, then grasping the wire 20 (ultimately through the ring 26) and pulling. The wire 20 will deform and lose its helical structure. In addition, since a portion of the wire 20 is embedded in the polymer tube 30, pulling the wire 20 will also pull the polymer tube 30, which is not mechanically reinforced by the wire and is therefore more easily deformed and easier to remove. This effect is particularly desirable in cases of persistent stenosis because the stent 10 is subjected to pressure from the body and traction on the stent 10 may injure the patient. When the expandable portion 22 and the wire 20 are softened, the removal of the stent 10 becomes safer and easier.

[0088] To speed up the removal of the stent, the polymer tube 30 can be divided into continuous sections. In both the compressed and expanded configurations, the strain in the wires 20 keeps the continuous sections in contact: the stent 10 behaves as if only one polymer tube 30 or one polymer tube was used. However, after the stent 10 cools and the strain in the wires relaxes, the continuous sections gain some relative mobility and can be removed more comfortably.

[0089] The present invention also relates to a method for manufacturing the stent 10 disclosed above. The method comprises the following steps:

[0090] i The shape memory wire 20 is formed into a helical coil;

[0091] ii. forming a polymer tube 30 having an outer surface having a spiral groove corresponding to the spiral coil;

[0092] iii. Inserting the spiral coil into the spiral groove of the polymer tube 30; and

[0093] iv. depositing a polymer on the helical coil and the polymer tube 30 to embed the helical coil in the polymer tube 30;

[0094] Therein, the helical coil includes at least one expandable portion 22, and the at least one expandable portion 22 can be in a compressed configuration or an expanded configuration.

[0095] The step of forming the polymer tube 30 may be molding (using a mold with grooves), cutting grooves in the polymer tube 30, embossing or additive manufacturing the polymer tube 30. Alternatively, the polymer tube 30 may be molded with the wire already placed in the mold.

[0096] The step of depositing the polymer onto the helical coil and polymer tube 30 may be molding, coating (eg, dip coating or spray coating), or additive manufacturing.

[0097] In an embodiment, the manufacturing method further comprises a functionalization step, which can be selected from the following: applying a hydrophilic treatment to the inner surface of the stent; applying a hydrophobic treatment to the outer surface of the stent; or applying a plasma treatment to the polymer.

[0098] In an embodiment, the manufacturing method further comprises the step of adding an active substance to be slowly delivered. For example, such an active substance may be embedded in the polymer tube 30 and released by diffusion of the polymer material. Alternatively, such an active substance may be deposited on the polymer tube 30 in a polymer matrix (in the form of a film or coating) to achieve controlled release.

[0099] The present disclosure also relates to a kit comprising:

[0100] • a stent 10 as disclosed above;

[0101] • Introduction tools for introduction, deployment and manipulation of stents; and

[0102] • A flushing channel, which allows fluid to flow to the stent 10 through the introduction tool.

[0103] The introduction tool can include: a distal end adapted to selectively receive or secure the stent 10 therein; a handle having one or more actuating portions (e.g., a trigger or actuator); and a tube or shaft portion. The tube or shaft portion can generally be flexible and operably communicated with the handle and the stent 10 to facilitate control of the stent 10 and deployment of the stent 10 within a patient's blood vessel or duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 is a schematic diagram showing the stent 10 according to Example 1 in a compressed configuration.

[0105] Figure 2 is a schematic diagram showing the stent 10 according to Example 1 in an expanded configuration.

[0106] Figure 3 is a schematic diagram showing the stent 10 according to Example 2 in a compressed configuration.

[0107] Figure 4is a schematic diagram showing the stent 10 according to Example 3 in a compressed configuration.

[0108] Figure 5 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 3.

[0109] FIG. 6 is a diagram showing a modification of Embodiment 3 in a compressed configuration ( Fig. 6A ) and expansion configuration ( Figure 6B ) is a schematic diagram of a bracket 10, which is designed with a ring 26.

[0110] Figure 7 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 4.

[0111] Figure 8 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 5.

[0112] Fig. 9 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 6.

[0113] Fig.10 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 7.

[0114] Fig.11 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 8.

[0115] Fig.12 is a schematic diagram showing the stent 10 in an expanded configuration according to Example 9.

[0116] In all figures, the stent 10 is presented with the proximal end on the left and the distal end on the right. The longitudinal axis (Oz) is shown pointing distally.

[0117] Example

[0118] The present invention is further illustrated by the following examples.

[0119] All examples were prepared using thermoplastic polyurethane (TPU) polymer and optionally a polymer coating for the polymer tube 30 , and using 0.66 mm diameter Nitinol as the wire 20 for the helical coil.

[0120] Example 1

[0121] like Figure 1As shown, in the compressed configuration of the stent 10, the axial length of the stent 10 is 40 mm (excluding the expandable portion 22), and the stent 10 includes a polymer tube 30 (with an inner diameter of 18 Fr / CH, an outer diameter of 24 Fr / CH, a corrugated outer surface and a fluctuation amplitude of 0.66 mm) and a nitinol wire 20. Seven continuous turns of the spiral coil are embedded in the polymer tube 30, wherein the pitch is constant at 5 mm. In addition, the expandable portion 22 has a U-shaped geometry and is wound around the distal end of the polymer tube 30, wherein two turns of the expandable portion 22 are spaced 4 mm apart, and the outer diameter in the compressed configuration is 24 FR / CH. Here, the expandable portion 22 is not coated.

[0122] After heat activation using physiological serum heated at 50°C, the expandable portion 22 expands and reaches an outer diameter of 42 Fr / CH, such as Figure 2 It can be observed that the polymer tube 30 and the expanded section are not coaxial in their expanded configuration.

[0123] By appropriately selecting the number of consecutive turns of the helical coil embedded in the polymer tube 30, similar stents 10 have been prepared with lengths of 40 mm, 50 mm, 60 mm, and 70 mm.

[0124] The stent 10 is intended for use in cases of benign prostatic hyperplasia.

[0125] Example 2

[0126] like Figure 3 As shown, in the compressed configuration of the stent 10, the stent 10 is 60 mm in length and includes a polymer tube 30 (18 Fr / CH inner diameter, 24 Fr / CH outer diameter) and a nitinol wire 20. The stent 10 includes three distinct regions.

[0127] The low flexibility area is located between the two expandable portions 22. The low flexibility portion consists of twenty consecutive turns in contact embedded in the polymer tube 30. The expandable portions 22 are identical, i.e., wound on the polymer tube 30 in a U-shaped geometry, wound on the polymer tube 30 at the distal and middle ends, with a spacing of 4 mm between two turns of the expandable portion 22, and an outer diameter of 24 FR / CH in the compressed configuration. Here, the expandable portion 22 is not coated.

[0128] On the central region, the very flexible zone adjacent to the expandable portion 22 in the middle of the stent consists of seven consecutive turns of a helical coil embedded in a polymer tube with a constant pitch of 5 mm.

[0129] On the proximal side, the semi-flexible zone adjacent to the flexible zone consists of fourteen consecutive turns of a helical coil embedded in the polymer tube 30 with a constant pitch of 2 mm.

[0130] After heat activation using physiological serum heated at 50°C, the expandable portion 22 expands and reaches an outer diameter of 42 vFr / CH.

[0131] The stent 10 exhibits varying flexibility along its length.

[0132] The central structure of the stent, ie, the flexible region and the expandable portion 22 located in the middle of the stent, corresponds to the stent 10 of Example 1.

[0133] Example 3

[0134] like Figure 4 As shown, in the compressed configuration of the stent 10, the axial length of the stent 10 is 40 mm (excluding the expandable portion 22), and the stent 10 includes a polymer tube 30 (with an inner diameter of 18 Fr / CH and an outer diameter of 24 Fr / CH) and a 0.66 mm nitinol wire. Seven consecutive turns of a spiral coil are embedded in the polymer tube, wherein the pitch is constant at 5 mm. In addition, two expandable portions 22 are also prepared. At the distal end, a U-shaped geometry protrudes from the polymer tube 30, wherein the two turns of the U-shaped geometry are spaced 4 mm apart and have an outer diameter of 24 FR / CH in the compressed configuration. At the proximal end, a conical geometry has three consecutive turns protruding from the polymer tube 30, wherein the pitch is 1.32 mm, and the outer diameter in the compressed configuration is 24 FR / CH.

[0135] Here, the distal U-shaped geometry is uncoated, while the proximal conical geometry has a polymer coating.

[0136] After heat activation using physiological serum heated at 50°C, the expandable portion 22 expands and the outer diameter of the distal U-shaped geometry reaches 42 Fr / CH and the proximal conical geometry reaches a conical structure, such as Figure 5 It can be observed that the polymer tube 30 and the U-shaped geometry expansion section are not coaxial in their expanded configuration.

[0137] In the variant shown in FIG6 ( Fig. 6A In a compressed configuration, Figure 6B The distal end of the polymer tube 30 is in an expanded configuration and includes a ring 26 and two U-shaped geometries in a coaxial direction with the polymer tube. Here, two helices are interwoven in the polymer tube 30 to create a high degree of helicity along the tube. Figure 5The stent 10 of FIG. 6 also shows a high degree of spiraling along the tube: the flexibility of the two stents 10 is comparable. However, during removal, the total length of the wire 20 of the stent 10 of FIG. 6 (from the loop 26 to the free end 24 of the wire 20) is almost Figure 5 The wire 20 of the stent 10 is half of the total length.

[0138] By appropriately selecting the number of consecutive turns of the helical coil embedded in the polymer tube 30, similar stents 10 have been prepared with lengths of 40 mm, 50 mm, 60 mm, and 70 mm.

[0139] Example 4

[0140] like Figure 7 As shown, in the expanded configuration of the stent 10, the axial length of the stent 10 is 70 mm (excluding the expandable portion 22), and includes a polymer tube 30 (with an inner diameter of 18 Fr / CH and an outer diameter of 24 Fr / CH) and a nitinol wire. The helical coil embedded in the polymer tube 30 has a variable helical pitch along the axis of the tube: the middle of the stent 10 is more flexible than the two ends of the stent 10. The stent 10 includes two expandable portions 22: a conical geometry with a ring 26 that creates a sealing structure; and a conical geometry that creates a drainage structure.

[0141] The stent 10 is intended to be placed at the base of the bladder with the drainage dilation portion located within the bladder (proximal end) and the sealing dilation portion located within the urethra (distal end). A ring 26 at the distal end allows for easy grasping of the stent 10 for removal. The stent 10 is particularly suitable for treating detrusor sphincter dyssynergia (DSD).

[0142] Example 5

[0143] like Figure 8 As shown, in the expanded configuration of the stent 10 of Example 4, the stent is adapted with nitinol having a diameter of 0.40 mm as a wire 20 with a constant degree of helical pitch and a polymer tube 30 (with an inner diameter of 7 Fr / CH and an outer diameter of 10.6 Fr / CH) that is flexible enough to adapt to the anatomical structure and peristaltic movement of the ureter and has a length of 30 mm. The stent 10 includes two expandable portions 22: a conical geometry with a ring 26 that creates a sealing structure and a conical geometry that creates a sealing structure. The stent 10 is particularly suitable for treating ureteral stenosis.

[0144] Example 6

[0145] like Fig. 9As shown, in the expanded configuration of the stent 10, the axial length of the stent 10 is 70 mm (excluding the expandable portion 22), and the stent 10 includes a polymer tube 30 (with an inner diameter of 18 Fr / CH and an outer diameter of 24 Fr / CH) and a nitinol wire. The stent 10 includes two expandable portions 22 of a conical geometry facing each other. In addition, the distal end of the stent 10 has a ring 26.

[0146] The stent 10 is intended to be placed at the urethral sphincter, with the expandable conical portions being located on either side of the sphincter, thereby ensuring a very secure anchoring. The stent 10 is particularly suitable for treating urethral strictures.

[0147] Example 7

[0148] like Fig.10 As shown, in the expanded configuration of the stent 10, the axial length of the stent 10 is 70 mm (excluding the expandable portion 22), and the stent 10 includes a polymer tube 30 (with an inner diameter of 18 Fr / CH and an outer diameter of 24 Fr / CH) and a nitinol wire. The stent 10 includes an expandable portion 22 with a U-shaped geometry at the distal end. In addition, the distal end of the stent 10 has a ring 26. At the proximal end, the wire 20 protrudes from the polymer tube 30, and the helical pitch is shorter than the helical pitch in the tube to adapt the flexibility of the stent 10 to the anatomical structure. The stent 10 is particularly suitable for treating benign prostatic hyperplasia with mid-lobe extension.

[0149] Example 8

[0150] like Fig.11 As shown, in the expanded configuration of the stent 10, the axial length of the stent 10 is 70 mm (excluding the expandable portion 22), and the stent 10 includes a polymer tube 30 (with an inner diameter of 18 Fr / CH and an outer diameter of 24 Fr / CH) and a nitinol wire. The stent 10 includes an expandable portion 22 with a U-shaped geometry having a ring 26 at the distal end and a conical geometry that creates a drainage structure at the proximal end. The stent 10 is particularly suitable for treating benign prostatic hyperplasia associated with bladder neck stenosis. Therefore, the helical pitch is shorter on the proximal side intended to be placed in the bladder neck.

[0151] Example 9

[0152] like Fig.12 As shown, in the expanded configuration of the stent 10 of Example 8, the stent 10 is adapted to a shorter polymer tube 30, the axial length of the polymer tube 30 being 20 mm (excluding the expandable portion 22). The stent 10 is particularly suitable for treating bladder neck stenosis.

[0153] Reference numerals:

[0154] 10: stent; 20: wire; 22: expandable portion; 24: free end of wire; 26: ring; 30: polymer tube.

Claims

1. A stent (10) for insertion into the lumen of an anatomical blood vessel or duct, comprising: • a polymer tube (30) wherein the hollow portion defines a longitudinal axis (Oz), • a single wire (20) formed into a helical coil, the helical coil comprising: i. a series of continuous turns of wire embedded in said polymer tube (30); and ii. at least one expandable portion (22) capable of being in a compressed configuration or an expanded configuration, the expandable portion being a shape memory material; wherein the axis of the helical coil is substantially parallel to the longitudinal axis (Oz); and The polymer tube (30) is radially rigid to prevent the diameter of the wire turns embedded in the polymer tube (30) from decreasing when the stent (10) is twisted about the longitudinal axis (Oz).

2. The bracket (10) according to claim 1, wherein: The at least one expandable portion (22) is located at the distal end of the stent (10) or the proximal end of the stent (10).

3. The bracket (10) according to claim 1 or 2, wherein: The at least one expandable portion (22) protrudes in front of the distal end of the polymer tube (30) or in front of the proximal end of the polymer tube (30).

4. The bracket (10) according to claim 3, wherein: The at least one expandable portion (22) comprises a series of continuous turns.

5. The bracket (10) according to claim 1 or 2, wherein: The at least one expandable portion (22) comprises a series of continuous turns wound around the polymer tube (30) in a compressed configuration.

6. The support (10) according to any one of claims 1 to 5, wherein • the inner surface of the polymer tube (30) is cylindrical, preferably, the inner surface of the polymer tube (30) is cylindrical and smooth; and / or • The outer surface of the polymer tube (30) is partially or completely corrugated.

7. The support (10) according to any one of claims 1 to 6, wherein: Successive turns of the helical coil embedded in the polymer tube (30) have a constant pitch.

8. The support (10) according to any one of claims 1 to 6, wherein: Successive turns of a helical coil embedded in the polymer tube (30) have a first constant pitch in a first portion of the polymer tube (30) and a second constant pitch in a second portion of the polymer tube (30), the second constant pitch being different from the first constant pitch.

9. The support (10) according to any one of claims 1 to 8, wherein: The at least one expandable portion (22) comprises a pair of turns directed in opposite directions and closed in a U-shape, such that the at least one expandable portion (22) defines a cylinder in its expanded configuration.

10. The stent (10) according to claim 9 further comprises a second expandable portion (22), the second expandable portion (22) comprising a pair of wire turns facing in opposite directions and closed in a U-shape, so that the second expandable portion (22) defines a cylinder in its expanded configuration.

11. The support (10) according to any one of claims 1 to 8, wherein: The at least one expandable portion (22) comprises a series of continuous turns in a compressed configuration and defines a conical shape in its expanded configuration.

12. The support (10) according to any one of claims 1 to 11, wherein: The at least one expandable portion (22) is coated with a polymer.

13. The support (10) according to any one of claims 1 to 12, wherein: The shape memory material is selected from polymers or metal alloys. Preferably, the shape memory material is a metal alloy of nickel and titanium.

14. The stent (10) according to any one of claims 1 to 13, for insertion into the lumen of a urinary tract vessel or duct.

15. A kit comprising: • A support (10) according to any one of claims 1 to 14; • an introduction tool for introducing, deploying and manipulating the stent (10); as well as • A flushing channel that allows fluid to flow through the introduction tool toward the stent (10).

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