Urological stent

Abstract

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

Description

Technical Field

[0001] The present disclosure relates to a stent for insertion into the lumen of an anatomical blood vessel or duct, the stent having an expandable portion that can be in a compressed form during insertion and can be in an expanded form after being placed in the blood vessel or duct.

Background Art

[0002] Stents are generally used to maintain or form a lumen within a body cavity. Stents are typically shaped as tubular intraluminal prostheses and are placed inside human or animal blood vessels or ducts. Stents can be used in various body cavities such as the urethra and blood vessels where occlusion of the body cavity can occur.

[0003] After placement, the stent needs to stay in place. Therefore, a fixing portion is provided to securely fix the stent within the body cavity. Known stents can be fixed at a desired position within the body cavity by expanding at least a part of the stent after insertion. However, stent migration is often observed. For example, a stent for the prostatic urethra positioned between the external urethral sphincter and the bladder neck may shift to the back of the bladder.

[0004] Furthermore, the mechanical flexibility of the stent needs to support the anatomical structure of the body cavity into which the stent is inserted and follow the physical characteristics of the body cavity, so as to provide overall flexibility, a higher quality of life, and a balance with respect to physiological and anatomical functions.

[0005] U.S. Patent Application US2003 / 040803 (U.S. Patent Application Publication No. 2003 / 0040803) discloses a urethral stent comprising a helical coil with a series of continuous turns made of a single wire. The diameter of the stent can be adjusted by twisting the helical coil, and the helical coil restores its diameter after releasing the torsional stress. The stent further comprises a soft webbing. Such a stent requires a complex insertion kit that enables keeping the stent in a twisted state during implantation. Further, this stent is easily compressible under radial pressure, just as when it is twisted. Finally, the webbing can be folded into pleats, especially when the stent diameter decreases, which restricts urine flow due to the limitation of the inner diameter of the stent and / or creates stagnation points for urine that can lead to infection.

[0006] U.S. Patent Application US2009 / 210045 (U.S. Patent Application Publication No. 2009 / 0210045) discloses a urethral stent based on a shape memory material. However, these stents are prone to tissue adhesion between the wire turns and cannot ensure a strong barrier between the inside and outside of the stent. Further, the shape of the above stent is ensured by a very compact structure where the continuous turns of the wire are in contact, resulting in an uncomfortable device that cannot bend to conform to the anatomical structure of the conduit.

[0007] The stent disclosed herein provides a balanced performance with respect to retention ability, strong fixation, and overall flexibility, thereby overcoming some or all of the disadvantages of the prior art.

SUMMARY OF THE INVENTION

[0008] Accordingly, the present disclosure relates to a stent comprising a polymeric tube having a hollow portion defining a longitudinal axis (Oz) and a single wire forming a helical coil. The stent is intended for insertion into the lumen of an anatomical blood vessel or conduit, preferably into the lumen of a urinary blood vessel or conduit. The helical coil is i. A series of continuous turns embedded in a polymeric tube, and ii. At least one expandable portion capable of being in either a compressed form or an expanded form, wherein the expandable portion is a shape memory material, the expandable portion, and comprises.

[0009] In addition, the axis of the helical coil is substantially parallel to the longitudinal axis (Oz), and the polymeric tube is radially rigid to prevent a decrease in the diameter of the turns embedded in the polymeric tube when the stent is twisted around the longitudinal axis (Oz).

[0010] That is, the wire is wound around the wall of the polymeric tube. And the polymeric tube thus obtained is very rigid radially and cannot be crushed when pressure is applied radially, that is, when pressure is applied in a direction perpendicular to the longitudinal axis (Oz), or when the wire is twisted. However, the polymeric tube is maintained in a flexible state axially and can bend to conform to the shape of the lumen to be inserted. Thus, the stent is a composite device in which the polymeric tube and the wire contribute synergistically to obtain the necessary mechanical properties (radially rigid and at the same time flexible to withstand compression due to natural movement or stenosis). Such flexibility is highly desirable in terms of patient comfort. For example, in urological applications, the shape of the urethra changes according to the patient's activities, that is, sitting / standing up, cycling, sexual relations, and the stent 10 needs to conform to these shape changes.

[0011] It should be noted that since the continuous turns are embedded in the polymeric tube, they cannot change shape from the compressed state to the expanded state. Thus, the continuous turns and the expandable portion are different parts of the helical coil.

[0012] In one embodiment, at least one expandable portion is at the distal end of the stent or at the proximal end of the stent.

[0013] In one embodiment, at least one expandable portion projects forward of the distal end of the polymeric tube or forward of the proximal end of the polymeric tube.

[0014] In one embodiment, at least one expandable portion comprises a series of continuous turns.

[0015] In one embodiment, at least one expandable portion comprises a series of continuous turns wound around the polymeric tube in a compressed form.

[0016] In one embodiment, the inner surface of the polymeric tube is cylindrical, and preferably, the inner surface of the polymeric tube is cylindrical and smooth. In one embodiment, the outer surface of the polymeric tube is partially or entirely corrugated. In a preferred embodiment, the inner surface of the polymeric tube is cylindrical and smooth, and the outer surface of the polymeric tube is partially corrugated.

[0017] In one embodiment, the continuous turns of the helical coil embedded in the polymeric tube have a constant pitch. Alternatively, the continuous turns of the helical coil embedded in the polymeric tube have a first constant pitch in a first portion of the polymeric tube and a second constant pitch different from the first constant pitch in a second portion of the polymeric tube.

[0018] In one embodiment, the helical coil comprises at least one expandable portion, and the at least one expandable portion comprises a pair of turns in opposite directions and a pair of turns closed in a U-shape, such that the at least one expandable portion in the expanded form defines a cylinder. In particular, the helical coil may comprise two expandable portions in a U-shape, and the second expandable portion comprises a pair of turns in opposite directions and a pair of turns closed in a U-shape, such that the second expandable portion in the expanded form defines a cylinder.

[0019] In one embodiment, at least one expandable portion comprises a series of continuous turns in a compressed form and defines a conical shape in an expanded form.

[0020] In one embodiment, at least one expandable portion is coated with a polymer.

[0021] In one embodiment, the shape memory material is selected from the group of polymers or metal alloys. Preferably, the shape memory material is a metal alloy of nickel and titanium.

[0022] The present disclosure further relates to - the stent disclosed above, - an introducer tool for introducing, deploying, and manipulating the stent, - a cleaning channel passing through the introducer tool for flowing a liquid towards the stent, and relates to a kit comprising the same. Definitions

[0023] In the present invention, the following terms have the following meanings.

[0024] "Distal" refers to the portion of the stent located near the orifice into which the stent is introduced, i.e., near the external urethra of the reproductive system.

[0025] "Expandable" refers to the portion of the stent whose dimensions can increase from a compressed state to an expanded state. Expansion is caused by external stimuli such as temperature change (thermally activated) or mechanical constraint (mechanically activated).

[0026] "Flexibility" refers to a general mechanical property that is not precisely measured in the present disclosure. Flexibility must be understood as the property of the stent being bendable or following the patient's movement with respect to the anatomical path and physiological anatomy functions. A flexible stent should not be uncomfortable and should not form folds that restrict the flow of liquid.

[0027] "French / Charrrière" (abbreviated as "Fr") refers to the diameter catheter scale. 1 mm is equal to 3 Fr. Therefore, the diameter of a round catheter in millimeters can be calculated by dividing the French size by 3. Charrrière has the same standard as French.

[0028] "Helical coil" refers to the continuous winding of a wire, and the said winding (or spiral) is approximately at regular intervals, the said winding is oriented approximately on the same axis, and the said winding has approximately the same diameter. Since the helical coil is deformable, its exact geometric shape is not clearly defined. In particular, the helical coil can be bent, stretched, or compressed.

[0029] "Pitch" refers to the repeating length between two consecutive windings of a helical coil having windings at regular intervals.

[0030] "Proximal" refers to the part of the stent that is located away from the orifice where the stent is introduced, that is, away from the external urethra of the reproductive system.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present disclosure relates to a stent 10 for insertion into the lumen of an anatomical blood vessel or duct. The stent 10 comprises a polymeric tube 30 having a hollow portion defining a longitudinal axis (Oz), and a single wire 20 forming a helical coil. The helical coil comprises 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 polymeric tube 30 is intended to maintain and support the lumen of the tube cavity into which the stent 10 is inserted, and the polymeric tube 30 is radially rigid to prevent the diameter of the turns embedded in the polymeric tube 30 from decreasing when the stent twists around the longitudinal axis (Oz). Further, the polymeric tube 30 remains axially flexible and can bend to conform to the shape of the inserted lumen. Further, the helical coil comprises an expandable portion 22 that can be in either a compressed or expanded form. This expandable portion 22 is made of a shape memory material. Thus, the stent 10 can be inserted and retained in a small-diameter shape with the expandable portion 22 compressed. After implantation, the shape memory material can be induced to take an expanded form. In the expanded region, the stent 10 applies a radial load to the wall of the duct cavity and is fixed. Finally, the shape memory material can be induced again to collapse its shape for removal of the stent 10. For example, the expandable portion 22 can be designed to have a first shape for introduction at room temperature, a first trigger at body temperature to expand and maintain the expanded state at a high temperature (about 45 °C or slightly above), and a second trigger at a low temperature (about 15 °C or slightly below) at which the expandable portion 22 loses its mechanical properties and softens for removal. In practice, since the expandable portion 22 no longer applies pressure and the wire 20 can be deformed into an elongated wire rather than a large-diameter coil, softening the wire 20 facilitates removal of the stent.

[0032] In the present disclosure, the continuous turns are embedded in the polymeric tube 30 and cannot change their form from a compressed state to an expanded state. Thus, the continuous turns and the expandable portion 22 are different parts of the helical coil.

[0033] The stent 10 disclosed in this specification is particularly suitable for urological applications and can be implanted in the ureter, bladder neck, or urethra.

[0034] In the present disclosure, a single wire 20 is used. By single, it means that the entire coil is made of a single wire. However, 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 intertwined helix. When the stent 10 has to be removed, the single wire 20 is advantageous. In fact, the physician can pull this wire 20 to move the stent 10. Since the wire 20 is at least partially embedded within the polymer tube 30, the polymer tube 30 is pulled simultaneously. Also, the portion of the wire 20 embedded in the polymer tube 30 does not elongate, and the overall length of the stent 10 for removal is shortened. Finally, since the wire 20 is a single element, the risk of breakage during removal is greatly limited.

[0035] 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, and the polymer tube 30 can have hydrophilicity and / or hydrophobicity to improve the flow of urine, reduce deposits and infections, and provide strong fixation. The polymer tube 30 can have tissue biocompatibility functions and magnetic resonance imaging biocompatibility functions. The polymer tube 30 can be plasma treated. The polymer tube 30 can further contain a drug or active substance that is slowly released into the tissue where the stent 10 is inserted to provide a therapeutic treatment.

[0036] Suitable polymers are, for example, thermoplastic polyurethane (TPU) and silicone.

[0037] The outer diameter of the polymer tube 30 can be selected within the range from 8 Fr / CH to 26 Fr / CH. Particularly suitable outer diameters are 10.6 Fr / CH and 24 Fr / CH.

[0038] The expandable portion 22 may be disposed anywhere along the entire length of the polymeric tube 30.

[0039] In one embodiment, the expandable portion 22 is disposed at the end, distal or proximal end, or other location of the stent 10, corresponding to the associated lesion, and maintains a strong fixing force taking into account physiological and anatomical constraints and characteristics. When the stent 10 includes two expandable portions 22, these expandable portions 22 may be disposed at both ends (distal and proximal ends) or one end and the central portion of the stent 10. For example, an expandable proximal portion fixed at the bladder neck level inside the bladder is specially designed to facilitate the flow of urine into the urethra and avoid residual urine volume during urination. In the prostatic urethra region, an expandable distal portion fixed on the external sphincter at the base of the prostate is specially designed to prevent the risk of migration and retrograde ejaculation. All of the expandable portions 22 are specially designed to facilitate the insertion, expansion, and removal of the stent 10.

[0040] In one embodiment, the expandable portion 22 projects in front of the distal end of the polymeric tube 30 or in front of the proximal end of the polymeric tube 30. This is advantageous when it is intended that the polymeric tube 30 maintain and support the lumen of the cavity while the expandable portion 22 is fixed in a stronger and healthier region having a different tissue resistance compared to the cavity in which the polymeric tube 30 is positioned. In particular, the expandable portion 22 may comprise a series of continuous coils. For example, the helical coil may be partially embedded in the polymeric tube 30 (holding portion) and may partially project from the polymeric tube 30 (expandable portion 22). When the stent 10 comprises two expandable portions 22, these expandable portions 22 may be arranged at both ends (distal end and proximal end) or one end and the central portion of the stent 10. FIGS. 4-5 are views of a stent 10 having two expandable portions 22 projecting at both ends of the polymeric tube 30. In urological applications, the configuration in which the expandable portion 22 projects in front of the distal end of the polymeric tube 30 is particularly advantageous for urine drainage. That is, the continuous coils at the distal end of the stent 10 assist in the drainage of fluid towards the polymeric tube 30 and avoid the accumulation of urine that can cause deposits and infections. In another urological application, the configuration in which the expandable portion 22 projects in front of the proximal end of the polymeric tube 30 is particularly advantageous for enabling the flow of fluid between the urethra and a conduit reaching the urethra, such as the ejaculatory duct. Indeed, in order to avoid retrograde ejaculation, the stent 10 must not block the flow of semen into the urethra. That is, the open structure of the expandable portion 22 is suitable for maintaining the urethra in an open state without closing the conduit.

[0041] Alternatively, the expandable portion 22 comprises a series of continuous turns wound onto the polymeric tube 30 in a compressed form in order to guarantee a uniform inner and outer diameter of the insertion system and the stent 10. This enables accurate optical visualization and easy insertion through the urinary tract in order to avoid the need for expansion prior to insertion. The expandable portion 22 may be located at the end, distal end, proximal end, or other location of the stent 10. If the stent 10 comprises two expandable portions 22, these expandable portions 22 may be located at both ends (distal end and proximal end) or one end and the central portion of the stent 10. FIGS. 1-2 are diagrams of a stent 10 having one expandable portion 22 at one end of the polymeric tube 30.

[0042] In the present disclosure, the polymeric tube 30 includes at least one hollow portion (which may also be referred to as a lumen within the stent region) through which liquid can flow or a surgical instrument can move. The hollow portion defines a longitudinal axis (Oz). The helical coil is embedded in the wall of the polymeric tube 30 such that the hollow portion is within the inner portion of the helical coil. That is, the helical coil is substantially parallel to the longitudinal axis (Oz).

[0043] Obviously, the diameter of the turns of the helical coil embedded in the polymeric tube 30 is larger than the inner diameter of the polymeric tube 30.

[0044] The inner diameter of the polymeric tube 30 can be selected within the range from 6 Fr / CH to 24 Fr / CH. Particularly preferred inner diameters are 7 Fr / CH and 18 Fr / CH.

[0045] The thickness of the polymeric tube 30 can be selected within the range from 0.2 mm to 1.4 mm, preferably from 0.2 mm to 0.66 mm.

[0046] Obviously, the diameter of the coil 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.

[0047] In one embodiment, the inner surface of the polymer tube 30 is cylindrical and preferably has a smooth surface. In another embodiment, the outer surface of the polymer tube 30 is corrugated, either in part or over the entire polymer tube 30.

[0048] The surface shape has several advantages. The smooth cylindrical inner surface provides the highest flow rate for a given cross-section, and thus the flow of the liquid is not impeded. Further, the smooth cylindrical inner surface limits deposits inside the stent 10 and then avoids the accumulation of inorganic salts and crystalline deposits, for example, derived from urine, which could potentially lead to blockage and as a result, infection due to urine stasis. The corrugated outer surface provides better contact with the walls of the cavity to be retained and avoids movement of the stent 10. Thus, such a corrugated outer surface limits the migration of the stent 10 and contributes to a firm fixation.

[0049] In a preferred embodiment, the inner surface of the polymer tube 30 is hydrophilic, for example, to improve the acceleration of urine flow and reduce deposits, and the outer surface is hydrophobic, for example, to avoid urine flow between the stent 10 and the tissue and provide a strong fixing force.

[0050] 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, with the peaks of the outer surface appearing where the wire 20 is located and the valleys of the outer surface appearing between two consecutive turns of the wire 20.

[0051] In the present disclosure, the flexibility of the stent 10 (flexibility along the longitudinal axis of the polymeric tube 30) results from the inherent mechanical properties of the polymeric tube 30 (such as material, thickness, etc.) and the inherent mechanical properties of the wire 20 (such as material, diameter, etc.), as well as the geometric shape of the wire 20 embedded in the polymeric tube 30 to form the composite device. Obviously, when the continuous turns of the helical coil embedded in the polymeric tube 30 are in contact, the helical coil cannot be easily bent, leading to low flexibility of the stent 10. Conversely, when the continuous turns are sufficiently separated by a flexible polymer, the bending is determined by the polymer properties, and the stent 10 can be very flexible. The shape of the wire 20 embedded in the polymeric tube 30 enables the design of the stent 10 to be adaptable with various degrees of flexibility to related lesions, such as physiological and anatomical characteristics like the peristaltic movement of the ureter, as well as related lesions such as stenosis, external pressure from adjacent organs, etc. The flexibility of the stent 10 may include deformation of the polymeric tube 30 (essentially, bending or peristaltic undulations). However, the polymeric tube 30 is radially rigid. In particular, the stent 10 may be used to counter stenosis. For example, when the conduit is blocked or nearly blocked, the stent 10 forms an open channel through the polymeric tube 30, and due to the mechanical properties of the polymeric tube 30 reinforced with the wire 20, the channel is reliably maintained in an open state. This is particularly applicable in the case of urine excretion. During urination, the urine flow is determined by the balance between the bladder pressure and the urethral orifice. In the case of stenosis, the residual urine remains in the bladder, which may cause complications such as infection or kidney stones. By maintaining the channel of the stent 10 in an open state, the storage of urine in the bladder is avoided. A polymeric tube 30 with an inner diameter of 18Fr / CH is particularly suitable for this case.

[0052] In one embodiment, the continuous turns of the helical coil embedded in the polymeric tube 30 have a constant pitch. In this embodiment, the flexibility of the stent 10 is uniform. This embodiment is suitable when it is expected that the holding structure applies a uniform load to the wall of the conduit cavity into which the holding structure is inserted, without low pressure points (which may cause patient discomfort or fatigue cracks in the stent 10).

[0053] In another embodiment, the continuous turns of the helical coil embedded in the polymeric tube 30 have a first constant pitch in a first portion of the polymeric tube 30 and a second constant pitch different from the first constant pitch in a second portion of the polymeric tube 30. This embodiment defines two regions with different flexibilities along the stent 10. This embodiment is particularly advantageous when the stent 10 has to support the wall of the cavity in one part and follow the patient's movements with respect to physiological anatomy in the other part.

[0054] More generally, the helical coil can define three or more portions each having a constant pitch. The pitch of the helical coil can also be variable according to a predetermined design, thereby providing "on-demand" flexibility along the stent 10.

[0055] In one embodiment, the expandable portion 22 comprises a pair of turns in opposite directions, a pair of turns closed in a U-shaped configuration. In the expanded configuration, the expandable portion 22 assumes a cylindrical shape (hereinafter referred to as a U-shaped configuration) defined by two circles corresponding to the two expanded turns. Such a cylindrical shape is particularly advantageous for applying a load to a large contact surface with the wall of the cavity, avoiding migration of the wire 20, and better fixing over a large area.

[0056] The U-shaped expandable portion 22 may further, in some cases, allow liquid to flow outside the polymer tube 30. In fact, the fixation is ensured by a simple wire 20 that does not block the possible flow path between the outer surface of the stent 10 and the tissue. This is particularly applicable in the case of the prostatic stent 10 that does not cause retrograde ejaculation.

[0057] In the case of a U-shaped configuration, the outer diameter of the expandable portion 22 in the compressed form can be selected within the range from 8 Fr / CH to 26 Fr / CH. Particularly preferred outer diameters are 10.6 Fr / CH and 24 Fr / CH. After expansion, the diameter of the expandable portion 22 can be selected within the range from 18 Fr / CH to 44 Fr / CH. Typically, the outer diameter in the expanded form is larger than the outer diameter in the compressed form by a multiple ranging from 1.5 to 2. Preferred pairs of diameters in the compressed and expanded forms are 10.6 / 21 Fr / CH and 24 / 42 Fr / CH.

[0058] In one embodiment, the cylinder defined by the two expanded coils is coaxial with the polymer tube 30.

[0059] Alternatively, the cylinder defined by the two expanded coils may not be coaxial with the polymer tube 30. In this particular configuration, the stent 10 can be placed within the cavity while maintaining a lumen between the stent 10 and the wall of the cavity. If the polymer tube 30 is not a tube (for example, in the case of a drain), this configuration allows the flow of liquid on the outer surface of the polymer tube 30. If the polymer tube 30 is a tube, this configuration allows two different flow paths, namely, the flow path inside the tube and the flow path outside the tube, which is particularly suitable when the stent 10 is placed at the location where two blood vessels or ducts join.

[0060] In one embodiment, the helical coil comprises two or more expandable portions 22, each expandable portion 22 being a pair of windings in opposite directions and comprising a pair of windings closed in a U-shape as disclosed above. In this embodiment, the stent 10 is fixed in the cavity on two or more cylindrical zones. Thus, the load exerted by each fixing point on the cavity wall is small, but all the fixing points together provide a firm fixation. Furthermore, the two U-shaped expandable portions 22 clarify the exact placement of the stent 10 and avoid any movement or migration of the stent 10. Also, it becomes possible to maintain the exact structure of the windings of the helical coil, and the generally flexible portions of the stent 10 are thus accurately positioned. Each U-shaped expandable portion 22 may or may not be coaxial with the polymer tube 30.

[0061] In one embodiment, the expandable portion 22 comprises a series of continuous windings in the compressed form and defines a conical shape (hereinafter referred to as a conical shape) in the expanded form. Such a conical shape is particularly advantageous when a conduit or blood vessel is connected to a larger cavity. The conical shape expands within the larger cavity, thereby avoiding migration of the stent 10 into the blood vessel or conduit.

[0062] In the case of the conical shape, the outer diameter of the expandable portion 22 in the compressed form can be selected within the range from 8 Fr / CH to 24 Fr / CH. Particularly preferred outer diameters are 10.6 Fr / CH and 24 Fr / CH. After expansion, the outer diameter of the largest winding of the expandable portion 22 can be selected within the range from 18 Fr / CH to 44 Fr / CH. Typically, the diameter of the largest winding in the expanded form is larger than the diameter in the compressed form by a multiple ranging from 1.5 to 2. Preferred pairs of diameters at the largest windings in the compressed and expanded forms are 10.6 / 21 Fr / CH and 24 / 42 Fr / CH.

[0063] More generally, the stent 10 of the present disclosure may have several expandable portions 22 selected from the group of cylindrical, U-shaped or conical shapes.

[0064] For example, the stent 10 of the present disclosure may comprise: · a U-shaped configuration at the distal end of the stent and another U-shaped configuration at the proximal end or center, · a U-shaped configuration at the distal end and a conical configuration at the proximal end, · a U-shaped configuration at the proximal end and a conical configuration at the distal end, or · a conical configuration at the distal end and another conical configuration on the proximal end. In all of these examples, the cylindrical, U-shaped, and conical configurations may project from the polymeric tube 30 or may be wound on the polymeric tube 30.

[0065]

[0066] In one embodiment, the helical coil is formed from a single wire 20, but preferably includes a loop 26 at the distal end of the stent 10. In this embodiment, the wire 20 is bent to form the loop 26 at one end of the stent 10. Such a loop 26 provides several advantages. First, the free end 24 of the wire 20 is not sharply cut, which can avoid the risk of tissue damage to the wire 20 at the tissue or sensitive and uncomfortable points. Second, the loop 26 is a point for actually gripping the stent 10 for easy removal. In fact, during the operation, a simple hook can be used to enter the loop 26 and easily pull on the wire 20 to easily remove the stent 10. This feature can be clearly seen at the distal end of FIG. 7. Third, since the wire 20 is bent, its apparent length is shortened. That is, after the extension of the helical coil, the length of the wire 20 having the loop 26 (from the loop 26 to the free end 24 of the single wire 20) can be half of the length of the same wire 20 without the loop 26. A shorter length is desirable for patient comfort and ease of operation during stent removal. This feature can be clearly seen in FIGS. 6 and 10-12, and the U-shaped distal end is actually a loop. The helical coil within the polymeric tube 30 is a combination of two helices.

[0067] When the end of the stent 10 has a U-shaped configuration with loops 26, the expanded configuration is two pairs of turns in opposite directions, with two pairs of turns closed in a U-shaped configuration (seen in FIGS. 6 and 10 - 12), which can provide better fixation. In fact, both U-shaped parts face each other and form two reinforcement parts for the same part of the stent 10. Such a structure cannot be pinched, thus providing a more stable fixation effect and retention. Finally, the height of such an expandable part 22, measured along the longitudinal axis (Oz), does not change significantly during expansion, and after the stent 10 is retained in the compressed configuration, the expandable part 22 expands and remains in the correct retention position. This improves the accuracy of retention. An expandable part 22 with an expanded diameter of 42Fr / CH is particularly suitable in this case.

[0068] In one embodiment, the helical coil is formed from a single wire 20 and comprises two loops 26, one loop 26 being at the distal end of the stent 10 and one loop 26 being at the proximal end of the stent 10. The loop 26 located at the proximal end of the stent 10 can assist in the manipulation and accurate placement of the stent 10.

[0069] The conical shape may have further features.

[0070] In the embodiment shown in FIG. 6, the conical shape of the distal end expansion portion forms a conduit with a continuous wall. In this shape, the expandable part 22 expands such that the spirals contract along the axis of the helical coil and contact without having a space between the spirals. Such a shape provides a sealing effect and prevents the flow of liquid and tissue growth through the helical coil. This effect is further improved when the expandable part 22 of the stent 10 is coated with a polymer, which ultimately acts as a seal since it has hydrophobic / hydrophilic and / or compressible properties. This feature is particularly notable at the proximal end of the stent in order to avoid liquid dispersion around the stent which ultimately leads to liquid trapping, and liquid trapping should be prevented to avoid potential infection around the stent.

[0071] Alternatively, the conical shape of the expansion portion forms a conduit having well-separated coils, as shown at the proximal end of FIG. 7. In this shape, the expansion portion behaves like a drain to assist the flow of liquid in the direction of the polymer tube. This feature is particularly notable at the proximal end of the stent to avoid liquid accumulation. For example, when a conical expansion portion is placed just above the bladder neck inside the bladder, urine drainage is complete. Preferably, the conical expansion portion protrudes in front of the distal end of the polymer tube 30.

[0072] In one embodiment, the expandable portion 22 is coated with a polymer. In particular, the expandable portion 22 may be coated with the same polymer (eventually including additives) used for the polymer tube 30. Preferably, the coating thickness is less than 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.

[0073] Regarding shape memory materials, polymers and metal alloys are suitable. The polymer shape memory material can be selected from the group of polyurethanes, polynorbornenes, or cross-linked polyethylene oxide (PEO)-polyethylene terephthalate (PET) block copolymers. The metal alloy shape memory material can be selected from the group of copper-aluminum-nickel and nickel-titanium. A metal alloy of nickel and titanium (known by the general name nitinol) is particularly suitable.

[0074] The preferred shape memory material is selected from among thermally activated shape memory materials. In particular, use in the human body is optimal when the shape memory material is formed at room temperature and maintains its stress structure at a normal human body temperature (40° C. or less). After the stent 10 is placed, the stent can be thermally expanded using a heating liquid that circulates around the stent 10 at a temperature above 40° C. but low enough to avoid any lesions, thereby inducing expansion of the expandable portion 22. The preferred transition temperature of the shape memory material is in the range from 45° C. to 65° C.

[0075] The other suitable shape memory materials are selected from among the mechanically activated shape memory materials. In this case, the stent 10 is implanted in the human body and then mechanically excited, for example, by force, torsion, or vibration, thereby releasing internal stress and causing a shape change.

[0076] In one embodiment, the expansion is not reversible. That is, after expansion by heating liquid or mechanical restraint, the stent 10 maintains its expanded form.

[0077] The stent 10 disclosed above is easily removable from the body. Typically, when cooled to less than 15°C, the shape memory material loses its rigidity and becomes elastic and can be deformed with a very small force. Thus, a physician can remove the stent 10 of the present invention by cooling the stent and then gripping (eventually by the loop 26) and pulling on the wire 20. The wire 20 deforms and loses its helical structure. Further, since a portion of the wire 20 is embedded in the polymer tube 30, pulling on the wire 20 also pulls the polymer tube 30, which is not mechanically reinforced by the wire, and as a result, it is more deformable and more easily withdrawn. This effect is particularly desirable in cases of persistent stenosis because the stent 10 is under pressure from the body and traction on the stent 10 could potentially injure the patient. After the expandable portion 22 and the wire 20 are softened, removal of the stent 10 becomes safer and easier.

[0078] To facilitate removal of the stent, the polymer tube 30 can be divided into continuous portions. In the compressed and expanded forms, the distortion of the wire 20 is maintained in contact with the continuous portions, and the stent 10 behaves as if only one polymer tube 30 were used or as if one polymer tube were used. However, after cooling of the stent 10 and relaxation of the wire distortion, the continuous portions acquire a certain degree of relative mobility and can be removed more comfortably.

[0079] The present disclosure further relates to a method for manufacturing the stent 10 disclosed above. This method comprises: i. forming the shape memory wire 20 into a helical coil; ii. forming a polymer tube 30 having a helical groove on the outer surface corresponding to the helical coil; iii. inserting the helical coil into the helical groove of the polymer tube 30; iv. depositing a polymer on the helical coil and the polymer tube 30 so as to embed the helical coil in the polymer tube 30; and the helical coil comprises at least one expandable portion 22 capable of being in either a compressed form or an expanded form.

[0080] The step of forming the polymer tube 30 can be molding using a mold having a groove, cutting the groove into the polymer tube 30, embossing the polymer tube 30, or additive manufacturing. Alternatively, the polymer tube 30 may be molded with the wire already placed in the mold.

[0081] The step of depositing a polymer on the helical coil and the polymer tube 30 can be overmolding, coating (such as dip coating or spray coating), or additive manufacturing.

[0082] In one embodiment, the manufacturing method further comprises a functionalization step that can be selected from the steps of subjecting the inner surface of the stent to a hydrophilic treatment, subjecting the outer surface of the stent to a hydrophobic treatment, or subjecting the polymer to a plasma treatment.

[0083] In one embodiment, the manufacturing method further comprises the step of incorporating a slowly delivered active substance. For example, such an active substance can be embedded in the polymer tube 30 and released by diffusion through the polymer material. Alternatively, such an active substance can be deposited in the form of a film or coating on the polymer tube 30 in the polymer matrix for controlled release.

[0084] The present disclosure further relates to · the stent 10 disclosed above, and · an introducer tool for introducing, deploying, and manipulating the stent, and · a cleaning channel passing through the introducer tool for flowing a liquid towards the stent 10, and relates to a kit comprising the same.

[0085] The introducer tool may include a distal end adapted to selectively receive or secure the stent 10, a handle having one or more operating parts (e.g., a trigger or actuator), and a tube or shaft portion. The tube or shaft portion is substantially flexible and is operably in communication with the handle and the stent 10 to facilitate control and deployment of the stent 10 within a patient's blood vessel or conduit.

Brief Description of the Drawings

[0086]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

[0087] In all the figures, the stent 10 is shown with the proximal side on the left and the distal side on the right. The longitudinal axis (Oz) is represented pointing to the distal side.

Example

[0088] The present invention will be further described in detail by the following examples.

[0089] All the examples are made using a polymer tube 30 and optionally a thermoplastic polyurethane (TPU) polymer for the polymer coating, and nitinol with a diameter of 0.66 mm as the wire 20 for the helical coil. Example 1

[0090] As shown in FIG. 1 in the compressed form, the stent 10 has a shaft length of 40 mm (excluding the expandable portion 22), and includes a polymer tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH, corrugated outer surface with undulations having a width of 0.66 mm) and a nitinol wire 20. Seven consecutive turns of the helical coil are embedded in the polymer tube 30 at a constant pitch of 5 mm. In addition, the expandable portion 22 has a U-shaped configuration wound around the polymer tube 30 (distal end), and both turns are separated by 4 mm, and the outer diameter in the compressed form is 24 FR / CH. Here, the expandable portion 22 is not coated.

[0091] Upon heat activation with physiologic serum heated to 50 °C, the expandable portion 22 expands and reaches an outer diameter of 42 Fr / CH as shown in Figure 2. It can be observed that the polymeric tube 30 is not coaxial with the expanded portion in the expanded form.

[0092] Similar stents 10 of lengths 40 mm, 50 mm, 60 mm, and 70 mm were created by appropriately selecting the number of consecutive turns of the helical coil embedded in the polymeric tube 30.

[0093] This stent 10 is intended to be used in cases of benign prostatic hyperplasia. Example 2

[0094] As shown in Figure 3 in the compressed form, the stent 10 is 60 mm in length and comprises a polymeric tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH) and a nitinol wire 20. The stent 10 includes three different regions.

[0095] A low flexibility region is located between the two expandable portions 22. The low flexibility portion is composed of 20 consecutive turns in contact, embedded in the polymeric tube 30. The expandable portions 22 are identical, i.e., wound on the polymeric tube 30 and have a U-shaped configuration (distal end and central) wound on the polymeric tube 30, with both turns separated by 4 mm and an outer diameter in the compressed form of 24 FR / CH. Here, the expandable portion 22 is not coated.

[0096] In the central region, a very flexible region adjacent to the expandable portion 22 located at the center of the stent is composed of 7 consecutive turns of a helical coil embedded in the polymeric tube at a constant pitch of 5 mm.

[0097] Proximally, a semi-flexible region adjacent to the flexible region is composed of 14 consecutive turns of a helical coil embedded in the polymeric tube 30 at a constant pitch of 2 mm.

[0098] Upon thermal activation with physiologic serum heated to 50°C, the expandable portion 22 expands to reach an outer diameter of 42 Fr / CH.

[0099] This stent 10 exhibits different flexibility along its length.

[0100] The central structure of this stent, i.e., the flexible region and the expandable portion 22 located at the center of the stent, is identical to the stent 10 of Example 1. Example 3

[0101] As shown in FIG. 4 in the compressed form, the stent 10 has a shaft length of 40 mm (excluding the expandable portion 22), a polymeric tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH), and a nitinol wire of 0.66 mm. Seven consecutive turns of the helical coil are embedded in the polymeric tube with a constant pitch of 5 mm. In addition, two expandable portions 22 are created. At the distal end, a U-shaped shape protrudes from the polymeric tube 30, with both turns separated by 4 mm and an outer diameter in the compressed form of 24 Fr / CH. At the proximal end, the conical shape has three consecutive turns protruding from the polymeric tube 30, with a pitch of 1.32 mm and an outer diameter in the compressed form of 24 FR / CH.

[0102] Here, the distal U-shaped shape is not coated, while the proximal conical shape is polymer-coated.

[0103] Upon thermal activation with physiologic serum heated to 50°C, the expandable portion 22 expands, as shown in FIG. 5, to reach an outer diameter of 42 Fr / CH for the distal U-shaped shape and a conical structure for the proximal conical shape. It can be observed that the polymeric tube 30 and the expanded portion of the U-shaped shape in the expanded form are not coaxial.

[0104] In the modification shown in FIG. 6 (compression form 6A and expansion form 6B), the distal end has a loop 26 and two U-shaped configurations in the coaxial direction with the polymer tube. Here, two spirals are intertwined within the polymer tube 30 to form a heightwise spiral along the tube. The stent 10 of FIG. 5 also shows a heightwise spiral along the tube, and the flexibility of both stents 10 is equivalent. However, during removal, the total length of the wire 20 of the stent 10 in FIG. 6 (from the loop 26 of the wire 20 to the free end 24) is approximately half of the total length of the wire 20 of the stent 10 in FIG. 5.

[0105] Similar stents 10 of lengths 40 mm, 50 mm, 60 mm, and 70 mm were created by appropriately selecting the number of continuous turns of the helical coil embedded in the polymer tube 30. Example 4

[0106] As shown in FIG. 7 in the expanded form, the stent 10 has a shaft length of 70 mm (excluding the expandable portion 22) and comprises a polymer tube 30 (inner diameter 18Fr / CH, outer diameter 24Fr / CH) and a nitinol wire. The helical coil embedded in the polymer tube 30 has a variable spiral pitch along the axis of the tube, and the flexibility of the stent 10 is higher at the central part compared to the ends. The stent 10 comprises two expandable portions 22, namely, a conical shape having a loop 26 leading to a sealing structure and a conical shape leading to a discharge structure.

[0107] This stent 10 is intended to be placed at the bladder base, with the discharge expansion portion at the proximal end of the bladder and the sealing expansion portion at the distal end of the urethra. The loop 26 at the distal end enables easy grasping of the stent 10 for removal. This stent 10 is particularly suitable for the treatment of detrusor sphincter dyssynergia (DSD). Example 5

[0108] As shown in FIG. 8 in the expanded form, the stent 10 of Example 4 is adapted using a nitinol with a diameter of 0.40 mm as the wire 20 having a certain spiral pitch and a polymer tube 30 with a length of 30 mm (inner diameter 7 Fr / CH, outer diameter 10.6 Fr / CH) having sufficient flexibility to conform to the anatomical structure and peristaltic movement of the ureter. The stent 10 includes two expandable portions 22, namely, a conical shape having a loop 26 connected to a sealing structure and a conical shape connected to the sealing structure. This stent 10 is particularly suitable for the treatment of ureteral stricture. Example 6

[0109] As shown in FIG. 9 in the expanded form, the stent 10 has a shaft length of 70 mm (excluding the expandable portion 22) and includes a polymer tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH) and a nitinol wire. The stent 10 includes two expandable portions 22 having conical shapes facing each other. Further, the distal end of the stent 10 has a loop 26.

[0110] This stent 10 is intended to be placed in the urethral sphincter, and the expandable conical portions are arranged on both sides of the sphincter, thereby ensuring a very strong fixation. This stent 10 is particularly suitable for the treatment of urethral stricture. Example 7

[0111] As shown in FIG. 10 in the expanded form, the stent 10 has a shaft length of 70 mm (excluding the expandable portion 22) and includes a polymer tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH) and a nitinol wire. The stent 10 includes one expandable portion 22 having a U-shaped shape at the distal end. Further, the distal end of the stent 10 has a loop 26. On the proximal side, the wire 20 protrudes from the polymer tube 30, and the spiral pitch is shorter than the pitch in the tube to adapt the flexibility of the stent 10 to the anatomical structure. This stent 10 is particularly suitable for the treatment of benign prostatic hyperplasia with middle lobe hypertrophy. Example 8

[0112] As shown in FIG. 11 in the expanded configuration, the stent 10 has a shaft length of 70 mm (excluding the expandable portion 22) and includes a polymeric tube 30 (inner diameter 18 Fr / CH, outer diameter 24 Fr / CH) and a nitinol wire. The stent 10 includes one expandable portion 22 having a U-shaped configuration with a loop 26 at the distal end and a conical shape at the proximal end that leads to a discharge structure. This stent 10 is particularly suitable for the treatment of benign prostatic hyperplasia associated with stenosis of the bladder neck. Accordingly, the spiral pitch is shorter on the proximal side that is intended to be placed at the bladder neck. Example 9

[0113] As shown in FIG. 12 in the expanded configuration, the stent 10 of Example 8 is adapted using a shorter polymeric tube 30 so as to have a shaft length of 20 mm (excluding the expandable portion 22). This stent 10 is particularly suitable for the treatment of stenosis of the bladder neck.

Description of the Reference Numerals

[0114] 10: stent / 20: wire / 22: expandable portion / 24: free end of the wire / 26: loop / 30: polymeric tube.

Claims

1. A stent (10) for insertion into the lumen of an anatomical blood vessel or duct, comprising: a polymeric tube (30) having a hollow portion defining a longitudinal axis (Oz); a single wire (20) forming a helical coil, the single wire (20) comprising: i. a series of continuous turns embedded in the polymeric tube (30); and ii. at least one expandable portion (22) capable of being in either a compressed form or an expanded form, 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 stent (10) further comprises a polymeric tube (30) which is radially rigid to prevent a decrease in the diameter of the turns embedded in the polymeric tube (30) when the stent (10) is twisted about the longitudinal axis (Oz).

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

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

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

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

6. The stent (10) according to any one of claims 1 to 5, wherein: - the inner surface of the polymeric tube (30) is cylindrical, preferably the inner surface of the polymeric tube (30) is cylindrical and smooth; and / or - the outer surface of the polymeric tube (30) is partially or wholly corrugated.

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

8. ​ ​ The continuous winding of the helical coil embedded in the polymer tube (30) has a first constant pitch in the first portion of the polymer tube (30) and a second constant pitch different from the first constant pitch in the second portion of the polymer tube (30). The stent (10) according to any one of claims 1 to 6.

9. The at least one expandable portion (22) comprises a pair of windings in opposite directions, the pair of windings being closed in a U-shape, such that the at least one expandable portion (22) in the expanded form defines a cylinder. The stent (10) according to any one of claims 1 to 8.

10. Further comprising a second expandable portion (22) comprising a pair of windings in opposite directions, the pair of windings being closed in a U-shape, such that the second expandable portion (22) in the expanded form defines a cylinder. The stent (10) according to claim 9.

11. The at least one expandable portion (22) comprises a series of continuous windings in the compressed form and defines a conical shape in the expanded form. The stent (10) according to any one of claims 1 to 8.

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

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

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

15. A kit comprising the stent (10) according to any one of claims 1 to 14, an introducer tool for introducing, deploying and manipulating the stent (10), a washing channel passing through the introducer tool for flowing liquid towards the stent (10), and a kit.

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