Urethral stent

Abstract

The present application relates to a urethral stent, comprising a tubular stent body and a retrieval portion, the stent body is composed of metal wires, the retrieval portion is arranged at least one end of the stent body in axial direction, the retrieval portion has a closed outer convex surface for cooperating with a catcher, and the maximum radial dimension of the retrieval portion is greater than the wire diameter of the metal wires. By setting the retrieval portion as a structure with a closed outer convex surface, the stable three-dimensional geometric shape can be maintained in cold water environment, and the structural support force will not be lost due to temperature reduction, so as to provide a stable and reliable catching support point for the catcher, effectively avoid the support point failure and slipping phenomenon caused by structural deformation in the catching process, reduce the number of repeated operations, shorten the operation time and reduce the pain of patients.

Description

Technical Field

[0001] This invention relates to the technical field of benign prostatic hyperplasia (BPH) treatment devices, and in particular to a urethral stent. Background Technology

[0002] Benign prostatic hyperplasia (BPH) is a common disease among middle-aged and elderly men, with a prevalence rate of over 50% in those over 60 years old and reaching 90% in those aged 70-80. The enlarged prostate compresses the urethra, causing symptoms such as difficulty urinating, urinary frequency, and urinary interruption. In severe cases, it can lead to bladder damage, urethral stones, and kidney dysfunction.

[0003] Most existing urethral stents do not have a retrieval structure, making them prone to slippage during intraoperative retrieval, requiring repeated attempts, prolonging the operation time, and increasing patient discomfort. A few urethral stents have a hook / loop-shaped retrieval structure, but because the stent is in a cold water environment during retrieval, where shape memory metal cannot effectively maintain its shape, the retrieval structure used to provide retrieval support points for these stents is difficult to maintain its hook / loop shape, thus easily leading to failure of the retrieval support point; moreover, this structure continuously compresses urethral tissue after implantation, increasing irritation and patient discomfort. Summary of the Invention

[0004] Therefore, it is necessary to address the problems of current urethral stent retrieval structures being unable to maintain structural stability in cold water environments, unable to provide stable capture support points, and causing significant irritation to the patient's urethra. A new type of urethral stent is needed that can stably provide capture support points and cause less irritation to the patient's urethra.

[0005] This application provides a urethral stent, including a tubular stent body and a retrieval part. The stent body is made of metal wire, and the retrieval part is disposed at at least one end of the stent body along its axial direction. The retrieval part has a closed convex curved surface for cooperating with a catcher, and the maximum radial dimension of the retrieval part is greater than the diameter of the metal wire.

[0006] In one embodiment, the support body is formed by spirally winding the metal wire.

[0007] In one embodiment, the metal wire has a circular cross-section perpendicular to the winding direction.

[0008] In one embodiment, the metal wire has a rectangular cross-section perpendicular to the winding direction, and the sides of two adjacent sections of the metal wire along the axial direction of the support body are in close contact.

[0009] In one embodiment, the outer wall of the stent body is provided with a drug reservoir for containing drugs.

[0010] In one embodiment, the drug reservoir extends along the length of the wire.

[0011] In one embodiment, the inner and / or outer walls of the stent body are provided with a coating for attaching drugs.

[0012] In one embodiment, the metal wire is a shape memory alloy, and the austenitic phase transformation completion temperature of the shape memory alloy is higher than the normal human body temperature.

[0013] In one embodiment, the austenitic phase transformation end temperature of the shape memory alloy is 40°C to 50°C.

[0014] In one embodiment, the metal wire is a shape memory alloy, and the austenitic phase transformation end temperature of the shape memory alloy is lower than or equal to the normal human body temperature.

[0015] In one embodiment, the austenitic phase transformation end temperature of the shape memory alloy is 20°C to 37°C.

[0016] In one embodiment, the shape memory alloy is a nickel-titanium alloy.

[0017] In one embodiment, the support body includes a cylindrical section and a flared section connected axially, the diameter of the flared section gradually increasing axially away from the cylindrical section.

[0018] In one embodiment, the retraction section is provided at both ends of the support body along the axial direction.

[0019] In one embodiment, the recycling section is a solid structure or a hollow structure with an internal porosity of less than 30%.

[0020] In one embodiment, the recovery section is spherical.

[0021] In this application, by setting the retrieval part as a structure with a closed convex curved surface, compared with the open hook / ring-shaped retrieval structure in the prior art, the closed convex curved surface can still maintain a stable three-dimensional geometric shape in a cold water environment (i.e., an environment in which shape memory metal cannot effectively maintain its superelasticity), and will not lose structural support due to temperature drop, thereby providing a stable and reliable retrieval support point for the capture device, effectively avoiding support point failure and slippage caused by structural deformation during the capture process, reducing the number of repeated operations, shortening the operation time and reducing patient pain; Meanwhile, since the maximum radial dimension of the retrieval section is larger than the wire diameter, this size difference makes it easier for the capture device to identify, attach, and capture the retrieval section, significantly improving the success rate of intraoperative capture and ease of operation. In addition, the closed convex curved surface makes smooth curved contact with the urethral tissue. Compared with the linear or point contact formed by the existing hook / loop structure and the embedded pressure of the open structure on the tissue, it can significantly reduce the continuous mechanical stimulation and local pressure on the urethral tissue, reduce tissue inflammation and patient discomfort during long-term implantation, and improve patient comfort while achieving reliable retrieval function. Attached Figure Description

[0022] Figure 1 This is a three-dimensional schematic diagram of the first embodiment of the urethral stent of this application; Figure 2 for Figure 1 A cross-sectional view of position AA in the middle; Figure 3 The second embodiment of the urethral stent in this application is in Figure 2 Cross-sectional view of the location; Figure 4 The third embodiment of the urethral stent in this application is in Figure 2 Cross-sectional view of the location; Figure 5 The fourth embodiment of the urethral stent in this application is in Figure 2 Cross-sectional view of the location; Figure 6 This is the fifth embodiment of the urethral stent in this application. Figure 2 Cross-sectional view of the location; Figure 7 for Figure 1 A schematic diagram viewed from the left.

[0023] Reference numerals: 10, stent body; 10a, cylindrical section; 10b, flared section; 11, drug tank; 12, membrane; 20, recovery section. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0030] Please refer to Figure 1 As shown, this application provides a urethral stent, including a tubular stent body 10 and a retrieval part 20. The stent body 10 is made of metal wire, and the retrieval part 20 is disposed at at least one end of the stent body 10 in the axial direction. The retrieval part 20 has a closed outward convex curved surface for cooperating with a catcher, and the maximum radial dimension of the retrieval part 20 is greater than the wire diameter of the metal wire.

[0031] In this application, by setting the retrieval section 20 to a structure with a closed convex curved surface, compared with the open hook / ring-shaped retrieval structure in the prior art, the closed convex curved surface can still maintain a stable three-dimensional geometric shape in a cold water environment (i.e., an environment in which shape memory metal cannot effectively maintain its superelasticity), and will not lose structural support due to temperature drop, thereby providing a stable and reliable retrieval support point for the capture device, effectively avoiding support point failure and slippage caused by structural deformation during the capture process, reducing the number of repeated operations, shortening the operation time and reducing patient pain; Meanwhile, since the maximum radial dimension of the retrieval section 20 is larger than the wire diameter of the metal wire, this size difference makes it easier for the capture device to identify, attach and capture the retrieval section 20, which significantly improves the success rate of intraoperative capture and ease of operation. In addition, the closed convex curved surface makes smooth curved contact with the urethral tissue. Compared with the linear or point contact formed by the existing hook / loop structure and the embedded pressure of the open structure on the tissue, it can significantly reduce the continuous mechanical stimulation and local pressure on the urethral tissue, reduce tissue inflammation and patient discomfort during long-term implantation, and improve patient comfort while achieving reliable retrieval function.

[0032] Specifically, a closed convex surface refers to a three-dimensional geometric structure formed by continuous curved surfaces that convex outwards as a whole and has no open ports (such as an ellipsoid, a sphere, or part of a teardrop-shaped closed body). In a cold water environment, the elastic modulus of shape memory metal decreases and its rigidity weakens. However, the closed convex surface, through the continuous tension distribution of the three-dimensional curved surface, can still maintain its macroscopic convex shape through geometric closed-loop characteristics even when the material flexibility increases, providing a reliable mounting support surface for the capture device. At the same time, the closed surface eliminates sharp angles and opening gaps, avoiding inflammatory stimulation and removal difficulties caused by ingrowth or embedding of urethral mucosal tissue, and significantly reducing the risk of complications from long-term implantation.

[0033] It is worth mentioning that, under the overall shape of a closed convex curved surface, the presence of local micro-concavities in the recovery section 20 is still considered "convex". That is, it is permissible for the surface of the recovery section 20 to have local micro-concavities caused by process or material characteristics, as long as its overall macro-contour is convex and can effectively provide capture support.

[0034] For ease of description, the portion connecting the metal wire and the retrieval section 20 is defined as the metal wire connection end. In this application, the radial dimension of the retrieval section 20 refers to the dimension of the cross-section of the retrieval section 20 perpendicular to the axis of the metal wire connection end, which is perpendicular to the central axis of the metal wire connection end. The maximum radial dimension of the retrieval section 20 is greater than the diameter of the metal wire, which means that among the various cross-sections perpendicular to the central axis of the metal wire connection end, there is one cross-section with a direction perpendicular to the central axis of the metal wire connection end, and the dimension of the retrieval section 20 in this direction of the cross-section is greater than the diameter of the metal wire. This dimensional difference can form a physical structure between the two for the catcher to sleeve or clamp, ensuring that the retrieval section 20 has sufficient radial protrusion height for the catcher to stably grasp.

[0035] Furthermore, in some embodiments, the recovery section 20 protrudes inward, outward, or simultaneously to both sides of the wire connection end along the radial direction of the support body 10; wherein, the inward protrusion can minimize mechanical stimulation to the urethral wall while providing a capture point facing the inside of the lumen; the outward protrusion facilitates capture operations from outside the urethra; the lateral protrusions balance capture convenience and tissue compatibility; all three directions meet the requirement that the maximum radial dimension is greater than the wire diameter, and all can provide an effective radial support surface for the capture device.

[0036] In some embodiments, the metal wire has a uniform wire diameter, in which case the maximum radial dimension of the recovery section 20 can be greater than the uniform wire diameter.

[0037] In some other embodiments, the wire diameter is not uniform. In this case, the maximum radial dimension of the retrieval part 20 is greater than the wire diameter at the connection end of the wire and the retrieval part 20, so as to ensure that no matter what kind of diameter variation design the wire adopts, the retrieval part 20 can form a clear geometric protrusion feature on the surface of the support body 10, providing clear tactile and visual identification marks for the capture device, and avoiding capture failure due to insufficient size difference in urethral narrowing or curvature environments.

[0038] In some embodiments, the support body 10 is made of metal wire, and can be a braided, laser-cut tubular or spiral structure, as long as the support body 10 is formed into a tubular shape and the retraction part 20 can be effectively combined with the end of the support body 10.

[0039] Specifically, the braided structure can form a recycling section 20 by the convergence of end metal wires; the laser-cut tube type can form a recycling section 20 by reserving a cutting shape; and the spiral type can form a recycling section 20 by the deformation of the end spiral ring.

[0040] Furthermore, please combine Figure 1 as well as Figure 2 As shown, in some embodiments, the support body 10 is formed by spirally winding metal wire.

[0041] The spiral coiled structure allows the stent body 10 to maintain its tubular support shape while possessing excellent axial flexibility and radial elasticity, enabling it to better adapt to the physiological curvature and peristalsis of the urethra.

[0042] Specifically, the metal wires are coiled in a spiral manner to form a continuous lumen support structure. The pitch of the wires can be adjusted according to clinical needs. A smaller pitch can provide stronger radial support and denser tissue coverage, while a larger pitch can improve the flexibility of the stent and the permeability of urine.

[0043] In addition, the end wires of the spiral winding structure can be bent, welded or melt-formed to directly form the recovery part 20, so that the recovery part 20 and the support body 10 form an integrated structure, avoiding stress concentration and breakage risks caused by additional connectors. At the same time, the recovery part 20 formed at the spiral end can naturally continue the direction of the wire, maintaining the continuity of the closed convex curved surface and the structural stability.

[0044] Please combine Figure 1 as well as Figure 2 As shown, in some embodiments, the metal wire has a circular cross-section perpendicular to the winding direction.

[0045] Circular cross-section metal wires have isotropic mechanical properties, which can evenly distribute stress during spiral winding and avoid metal fatigue caused by local stress concentration. At the same time, the circular cross-section has the smallest perimeter-to-cross-sectional area ratio, and its smooth curved surface can significantly reduce the coefficient of friction when in contact with the urethral mucosa, thereby reducing tissue damage and inflammatory response.

[0046] In terms of processing and manufacturing, the round wire is a standard profile, which is easy to obtain precise dimensional accuracy and surface quality through processes such as drawing and annealing. This is beneficial for controlling the forming accuracy of the recovery section 20, ensuring the geometric symmetry and surface smoothness of the closed convex curved surface, thereby providing a reliable contact interface for the catcher.

[0047] Please refer to Figure 3 As shown, in some embodiments, the cross-section of the metal wire perpendicular to the winding direction is rectangular, and the sides of two adjacent metal wire segments along the axial direction of the support body 10 are closely attached.

[0048] It is understandable that, compared to circular cross-section metal wires, rectangular cross-section metal wires can provide stronger radial support when spirally wound. This is because rectangular cross-sections have a larger moment of inertia in the radial direction, which significantly enhances their ability to resist radial compressive deformation.

[0049] Meanwhile, since the sides of two axially adjacent metal wires are in close contact, the planar contact characteristics of the rectangular metal wires make the gap between adjacent metal wires change less when the support is bent. This can effectively prevent the lumen from collapsing or the gap from widening due to the bending of the support, thereby maintaining the unobstructed flow of the channel established by the support.

[0050] Furthermore, the rectangular cross-section of the metal wire has higher bending stiffness when subjected to axial stress, which significantly reduces the degree of axial deformation of the stent body 10 when subjected to urethral peristalsis or external traction, thus improving the axial stability of the stent. More importantly, the rectangular metal wire structure that fits tightly on the sides greatly reduces the gap between the metal wires, significantly improving the stent's anti-displacement ability and effectively preventing the stent from sliding axially or circumferentially in the urethra. At the same time, the dense side-fitting structure reduces the risk of urethral mucosal tissue growing into the stent gap, reducing the risk of tissue adhesion and bleeding when the stent is removed after long-term implantation.

[0051] Furthermore, in some embodiments, the rectangular cross-section of the metal wire has a side length along the axial direction of the stent body 10 that is greater than the side length along the radial direction, so as to reduce the wall thickness of the stent body 10, reduce the diameter of the stent body 10 while keeping the cross-sectional area of ​​the internal channel of the stent body 10 the same, and reduce the discomfort of the patient after urethral stent implantation.

[0052] Please combine Figure 4 as well as Figure 5As shown, in some embodiments, the outer wall of the stent body 10 is provided with a drug groove 11 for containing drugs.

[0053] The drug reservoir 11 is recessed on the surface of the metal wire and is used to directly contain solid or semi-solid drug preparations (such as drugs that prevent tissue hyperplasia or other drugs).

[0054] By placing the drug reservoir 11 on the outer wall of the stent body 10, the drug can be released directly onto the urethral wall tissue, achieving local targeted drug delivery. This significantly reduces the side effects of systemic medication while inhibiting abnormal proliferation of urethral tissue. Specifically, the drug reservoir 11 can be loaded with anti-proliferative drugs to inhibit excessive tissue proliferation after prostate urethral surgery, or it can be loaded with anti-inflammatory, antibacterial, or analgesic drugs to alleviate postoperative inflammatory responses and infection risks. This effectively prevents restenosis and complications after stent implantation without increasing systemic toxicity.

[0055] Please combine Figure 4 as well as Figure 5 As shown, in some embodiments, the drug groove 11 extends along the length of the metal wire to form a continuous or discontinuous strip-shaped groove structure.

[0056] This extended design can be continuously distributed along the spiral trajectory or braided path of the metal wire, ensuring that the drug is evenly distributed in the axial and circumferential directions of the stent body 10; when the stent body 10 expands and adheres to the wall, the drug in the drug groove 11 can form a continuous drug treatment band along the urethral wall, avoiding tissue irritation or insufficient efficacy caused by excessively high or low local drug concentration.

[0057] Meanwhile, the tank structure extending along the length increases the drug loading capacity, enabling long-term sustained drug release, reducing the need for frequent postoperative administration, and improving patient compliance.

[0058] Please refer to Figure 6 As shown, in some embodiments, the inner wall and / or outer wall of the stent body 10 are provided with a coating 12 for attaching drugs.

[0059] The coating 12 can be attached to the surface of the metal wire by spraying, dipping, or hot-pressing to form a polymer layer (such as polyurethane, polylactic acid, silicone, or drug-loaded polymer coating) with drug carrier function. Therapeutic drugs can be uniformly dispersed inside the coating 12 or attached to its surface, and controlled release of the drug can be achieved through the degradation or diffusion mechanism of the coating layer.

[0060] When the membrane 12 is placed on the outer wall, it can directly release drugs into the urethral tissue and reduce the mechanical friction of the metal wire on the mucosa; when placed on the inner wall, it can inhibit bacterial adhesion and stone formation in the urine in the lumen; when placed on both sides, it can simultaneously achieve the anti-stone / antibacterial function of the inner surface and the anti-proliferation / anti-inflammatory function of the outer surface, comprehensively improving the biocompatibility and therapeutic effect of the stent.

[0061] In some embodiments, the metal wire is a shape memory alloy, and the austenitic phase transformation completion temperature (Af temperature) of the shape memory alloy is higher than the normal human body temperature, i.e., a temperature-controlled stent.

[0062] This type of temperature-controlled stent is in the martensitic phase in environments below Af temperature (such as room temperature or cold water environment), has a low elastic modulus and good flexibility, which makes the stent easy to adjust its position and easy to compress and deliver during implantation; and once the implantation position is determined, by injecting warm water above Af temperature into the urethra, the stent body 10 undergoes an austenitic phase transformation and expands to the preset ideal shape, thereby supporting the narrowed urethra.

[0063] Specifically, when the stent needs to be retrieved post-operatively, cold water (below the Af temperature) is injected into the urethra to restore the stent body 10 to a soft martensitic state. At this time, although the overall flexibility of the metal wire increases, the closed convex curved surface of the retrieval part 20 can still maintain a stable macroscopic convex shape in the cold water due to its three-dimensional geometric closed-loop structure, providing a reliable radial support surface for the grasper and effectively avoiding grasping point failure. Therefore, this temperature-controlled design allows doctors to repeatedly adjust the stent position until the optimal position is achieved during the implantation process, improving implantation accuracy.

[0064] Furthermore, in some embodiments, the austenitic phase transformation end temperature of the shape memory alloy is 40°C to 50°C.

[0065] This temperature range is higher than the normal human body temperature (37°C), ensuring that the stent can stably maintain its martensitic phase or pre-deformed state under body temperature conditions, and will not restrict the position adjustment during implantation due to unexpected expansion triggered by body temperature; at the same time, the temperature range of 40°C to 50°C is easy to achieve in clinical practice (by injecting warm water) and will not cause thermal damage to the urethral mucosa (usually below the tissue protein denaturation temperature threshold), thus achieving precise triggering of temperature-controlled expansion while ensuring operational safety.

[0066] In addition, this temperature range also takes into account the performance of the support during cold water recovery, ensuring that the recovery section 20 remains in a soft state in sync with the support body 10 under normal cold water rinsing (about 15-25℃) conditions, which facilitates overall retraction, while the closed convex curved surface still maintains its geometric stability.

[0067] In some embodiments, the metal wire is a shape memory alloy, and the austenitic phase transformation end temperature of the shape memory alloy is lower than or equal to the normal human body temperature, i.e., a self-expanding scaffold.

[0068] These self-expanding stents simplify the surgical procedure. Doctors only need to deliver the compressed stent to the target location, and the stent will automatically expand and fix itself under the influence of body temperature. Specifically, these self-expanding stents are in the martensitic or partially austenitic phase at room temperature or slightly lower temperatures, but once implanted in the human body (at a 37°C environment), they immediately or gradually complete the austenitic phase transformation and automatically expand to the preset shape without the need for additional heating.

[0069] It is understandable that shape memory alloys are more common due to their lower temperature requirements for Af, and their material cost is lower than that of the aforementioned temperature-controlled stents. At the same time, since the stent can maintain the austenitic phase or stable state at normal ambient temperatures, no special cold chain transportation and low-temperature storage conditions are required, and the transportation and storage costs are comparable to those of conventional medical consumables, significantly reducing the overall medical cost.

[0070] During the retrieval process, although the support is austenitic and has a certain rigidity at body temperature, it is cooled to below Af by injecting cold water, and the support body 10 regains its flexibility. At this time, the closed convex curved surface of the retrieval part 20 still maintains structural stability in the cold water environment, providing a clear retrieval support point for the capture device.

[0071] Furthermore, in some embodiments, the austenitic phase transformation end temperature of the shape memory alloy is 20°C to 37°C.

[0072] The lower limit of 20°C ensures that the stent can maintain the martensitic phase or be easily compressible at normal room temperature or refrigeration temperature, so as to maintain the compressed shape in the delivery sheath without self-expansion; while the upper limit of 37°C ensures that the stent can completely transform into the austenitic phase and fully expand to the designed shape at human body temperature, providing sufficient radial support.

[0073] Furthermore, in some embodiments, the shape memory alloy is a nickel-titanium alloy.

[0074] Nickel-titanium alloys possess excellent biocompatibility, corrosion resistance, and fatigue resistance, making them suitable for long-term implantation in the human urethra. Specifically, by adjusting the nickel-titanium atomic ratio and heat treatment process, the austenitic phase transformation completion temperature can be precisely controlled, thereby achieving different phase transformation temperature ranges.

[0075] In some embodiments, the recovery section 20 and the stent body 10 adopt an integral molding structure to ensure that the recovery section 20 and the stent body 10 have completely consistent material phase transformation characteristics and enter the martensitic state synchronously in a cold water environment, avoiding deformation inconsistency caused by material differences; eliminating welding or mechanical connection points to prevent the risk of fracture caused by stress concentration during recovery; and reducing corrosion and inflammatory reactions caused by dissimilar material interfaces, thereby improving the safety of long-term implantation and the reliability of recovery.

[0076] Please refer to Figure 1 As shown, in some embodiments, the support body 10 includes a cylindrical section 10a and a flared section 10b connected along the axial direction, the diameter of the flared section 10b gradually increasing along the axial direction away from the cylindrical section 10a.

[0077] The gradual flaring structure of the flaring segment 10b enables self-anchoring at the physiological narrowing of the urethra, effectively preventing axial displacement of the stent body 10 under urination pressure or urethral peristalsis. At the same time, the tapered outer surface of the flaring segment 10b forms a gradual contact with the urethral wall, which significantly reduces shear stress on the urethral mucosa compared to the sudden truncation of a straight tube structure, thus reducing the risk of tissue ischemia and ulceration.

[0078] Specifically, the flared section 10b can be located at the proximal end (bladder side) and / or distal end (urethral side) of the support body 10. When the flared section 10b and the retrieval section 20 are located at the same end, the flared structure can also provide additional radial support for the retrieval section 20, further enhancing the structural stability of the retrieval section 20 in a cold water environment and ensuring that the closed convex curved surface can still maintain an effective support shape when subjected to radial compression by the catcher.

[0079] Please refer to Figure 1 As shown, in some embodiments, the support body 10 is provided with a retraction section 20 at both ends along the axial direction.

[0080] This dual-end retrieval design provides the surgeon with a two-way retrieval option, allowing the surgeon to choose either the proximal or distal retrieval section 20 for retrieval based on the convenience of the surgical approach. For example, if one retrieval section 20 is difficult to retrieve due to tissue encapsulation, stone attachment, or deep location, the surgeon can immediately switch to the other retrieval section 20 for retrieval, thereby improving the success rate and safety of the surgery.

[0081] In addition, both recovery sections 20 have a closed convex curved surface structure, which independently provides a stable capture support point for the capture device in a cold water environment. The double-end symmetrical design helps the stent maintain axial balance in the urethra and reduces stent tilting or local compression caused by single-end protrusion.

[0082] Please combine Figure 1 as well as Figure 7As shown, in some embodiments, with the axis of the support body 10 as the vertex, the included angle α between the projections of the two recovery parts 20 along the axial direction of the support body 10 satisfies: 0°<α≤45°.

[0083] This angle range balances ease of capture with a compact structure.

[0084] Specifically, α greater than 0° ensures that the two recovery sections 20 are staggered in the circumferential direction, avoiding the dilemma that the capture device cannot simultaneously identify or selectively fit into the single-end recovery section due to the two being completely overlapped in the axial direction. At the same time, it also prevents the local radial dimension from being too large due to the overlap of the two recovery sections 20 in the axial direction, reducing excessive pressure on the urethral wall. The fact that α is less than or equal to 45° ensures that the two retrieval sections 20 are relatively close in the circumferential direction, allowing the surgeon to switch between the two retrieval sections 20 to capture targets by slightly rotating the capture device without having to make large adjustments to the instrument angle, thus simplifying the surgical procedure.

[0085] Furthermore, in some embodiments, α may be 15°, 30°, or 45° to achieve an optimal balance between capture flexibility and structural stability.

[0086] In some embodiments, the recycling section 20 is a solid structure or a hollow structure with an internal porosity of less than 30%.

[0087] This design enhances the structural rigidity and shape retention of the recovery section 20 in cold water environments. It is understandable that when shape memory alloys are in cold water environments (such as injection fluids below body temperature), their hyperelasticity decreases and their flexibility increases. If the recovery section 20 uses a high-porosity mesh or hollow structure, it is prone to collapse or deformation, leading to failure of the capture support points. A solid structure or a low-porosity (<30%) hollow structure, through the volume support of the material itself and continuous surface tension, ensures that the closed convex curved surface maintains its macroscopic geometric shape in a low-temperature flexible state, providing reliable radial support for the capture device.

[0088] Preferably, in some embodiments, the recovery section 20 is a hollow structure (such as a thin-walled spherical shell) with an internal porosity of less than 30%, which can reduce the overall weight of the stent while ensuring structural strength and reducing the long-term mechanical load of the implant on the urethra.

[0089] Please combine Figure 1 as well as Figure 7 As shown, in some embodiments, the recovery section 20 is spherical.

[0090] The spherical structure has excellent isotropic characteristics. No matter what circumferential angle or axial direction the capture device approaches from, the spherical surface can provide a continuous, uniform and symmetrical capture support surface, which greatly simplifies the alignment operation during the operation and reduces the risk of capture failure due to angular deviation.

[0091] Furthermore, the spherical shape, without sharp edges or corners, ensures that its contact with urethral tissue is a pure surface contact or point contact (cutting point), eliminating the cutting and continuous pressure on the urethral mucosa caused by the line contact or acute angle contact of the hook / loop structure in the prior art, and significantly reducing tissue inflammation and fibrosis.

[0092] In a cold water environment, the spherical structure distributes internal stress evenly across the entire spherical surface through its geometric closure characteristics. Even if the elastic modulus of the shape memory alloy decreases, the spherical recovery section 20 can still maintain its convex profile without collapsing, providing 360° circumferential stable support for the capture device.

[0093] Specifically, in some embodiments, the spherical recovery section 20 can be formed by melting the end of a metal wire into a ball, laser welding a pre-made ball, or machining it integrally. Its ball diameter is larger than the diameter of the metal wire, ensuring that a clear geometric protrusion is formed on the surface of the support body 10.

[0094] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A urethral stent, characterized in that, It includes a tubular support body (10) and a retrieval part (20). The support body (10) is made of metal wire. The retrieval part (20) is disposed at at least one end of the support body (10) in the axial direction. The retrieval part (20) has a closed convex curved surface for cooperating with a catcher. The maximum radial dimension of the retrieval part (20) is greater than the diameter of the metal wire.

2. The urethral stent according to claim 1, characterized in that, The support body (10) is formed by spirally winding the metal wire.

3. The urethral stent according to claim 2, characterized in that, The metal wire has a circular cross-section perpendicular to the winding direction.

4. The urethral stent according to claim 2, characterized in that, The metal wire has a rectangular cross section perpendicular to the winding direction, and the sides of two adjacent metal wires along the axial direction of the support body (10) are closely attached.

5. The urethral stent according to claim 1, characterized in that, The outer wall of the stent body (10) is provided with a drug reservoir (11) for containing drugs.

6. The urethral stent according to claim 5, characterized in that, The drug reservoir (11) extends along the length of the metal wire.

7. The urethral stent according to claim 1, characterized in that, The inner and / or outer walls of the stent body (10) are provided with a coating (12) for attaching drugs.

8. The urethral stent according to claim 1, characterized in that, The metal wire is a shape memory alloy, and the austenitic phase transformation completion temperature of the shape memory alloy is higher than the normal human body temperature.

9. The urethral stent according to claim 8, characterized in that, The austenitic phase transformation end temperature of the shape memory alloy is 40℃~50℃.

10. The urethral stent according to claim 1, characterized in that, The metal wire is a shape memory alloy, and the austenitic phase transformation end temperature of the shape memory alloy is lower than or equal to the normal human body temperature.

11. The urethral stent according to claim 10, characterized in that, The austenitic phase transformation end temperature of the shape memory alloy is 20℃~37℃.

12. The urethral stent according to any one of claims 8 to 11, characterized in that, The shape memory alloy is a nickel-titanium alloy.

13. The urethral stent according to claim 1, characterized in that, The support body (10) includes a cylindrical section (10a) and a flared section (10b) connected along the axial direction, the diameter of which gradually increases along the axial direction away from the cylindrical section (10a).

14. The urethral stent according to claim 1, characterized in that, The support body (10) is provided with the recycling section (20) at both ends along the axial direction.

15. The urethral stent according to claim 1, characterized in that, The recovery section (20) is a solid structure or a hollow structure with an internal porosity of less than 30%.

16. The urethral stent according to claim 1, characterized in that, The recovery section (20) is spherical.

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