CN113599018A

CN113599018A - Ureter bracket

Info

Publication number: CN113599018A
Application number: CN202110838209.5A
Authority: CN
Inventors: 罗万川; 王强
Original assignee: Li Aikou Advanced Materials Private Co ltd; Shanghai Huodian Medical Equipment Co ltd
Current assignee: Li Aikou Advanced Materials Private Co ltd; Shanghai Huodian Medical Equipment Co ltd
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2021-11-05
Also published as: WO2023001302A1; CN115813604A; CN116019602A

Abstract

The invention discloses a ureteral stent, which comprises a stent body and an expandable coating arranged on the outer surface of the stent body, wherein the thickness of the expandable coating corresponding to a narrow part of a ureter is larger than that of the expandable coating of the other part of the ureter. With the structure, the expandable coating can better resist the compression force of a narrow part of the ureter, so that the ureter after treatment has a more uniform inner diameter and better treatment effect.

Description

Ureter bracket

Technical Field

The invention relates to the field of medical stents, in particular to a ureteral stent.

Background

Ureteral stenosis is not clinically common, and except congenital stenosis, secondary ureteral stenosis is mainly caused by iatrogenic stenosis, calculus incarceration, infection, endometriosis, retroperitoneal fibrosis, malignant tumor, radiotherapy and the like.

The traditional treatment mode is open surgery, but the open surgery for ureteral reconstruction has the defects of large wound, complex surgery, more complications, slower postoperative recovery, easy relapse and the like. With the development of endoscope technology, the operation treatment in the ureteral stenosis cavity is gradually popularized, firstly, the ureteral sacculus expansion under the endoscope or the ureteral stenosis internal incision operation is selected, and a ureteral stent needs to be placed after the operation to prevent the recurrence of the stenosis. At present, the double J tubes commonly used in clinic have the defects of uncomfortable feeling after tube placement, formation of a bracket shell, even induction of calculus generation, need of regular replacement and the like. In recent years, metal stents are applied to clinic, have the advantages of biocompatibility, flexibility and corrosion resistance, still cannot be permanently placed in a body, have many complications, are easy to displace particularly, and greatly reduce the cure rate of ureteral stenosis.

The metal bracket is mainly Resonance produced by COOK company of America^TMAnd Silhouette manufactured by APPLID medical corporation^TMThe spiral coil design increases tensile strength and stability simultaneously, greatly prolongs the retention time of the metal stent, has fewer complications than double J tubes, has better treatment effect on ureteral stenosis caused by malignant tumors, and still has the problems of stent obstruction, patient discomfort, urinary tract infection and the like. In recent years, new metal stents have been developed which do not cover the entire length of the ureter and are only used for the narrow ureter, also called expandable metal ureteral stents, and can be classified into self-expansion and balloon expansion according to the expansion mechanism. Balloon expansion is limited in clinical application because of the existence of obstructive urothelial hyperplasia, so clinically expandable metal ureteral stents are generally referred to as self-expandable metal stents. The first expandable metal ureteral stent is a Wallstent manufactured by Boston scientific, and is a steel wire mesh made of stainless steel, and can be placed in a forward or reverse direction. Although the situation that the tumor growth presses the stent and even the stent is blocked cannot be avoided, the stent patency rate can reach 54 percent. The disadvantage is that it was not originally designed for use in the ureter and therefore stent removal presents difficulties.

Although expandable metal ureteral stents offer many advantages over traditional double J-tubes, too many complications limit their widespread clinical use. Early stent-related adverse reactions include iatrogenic injury, stent migration and patient discomfort, late stent-related complications including infection and difficulty in stent replacement, hardware failure, and stent fouling. In rare cases, prolonged stent placement can lead to ureteric arterial fistulae and iliac erosion. In addition, randomized clinical trials and long-term follow-up observations regarding the therapeutic efficacy of expandable metal ureteral stents in a large number of cases lack, nor do clinical data compare the therapeutic efficacy of various stents. Meanwhile, the stent is found to be displaced to different degrees after operation, and the position is very difficult to adjust once the stent is displaced. In addition, once the stent is output, if the stent is improperly placed and cannot be recovered, the psychological burden of an operating doctor and the economic burden of a patient are increased.

US2012/0123527a1 discloses a ureteral stent comprising a reticulated metal-based expandable stent-graft body and a hydrogel coating provided on the outer surface of the stent-graft body, which is slightly expandable after being infiltrated with a liquid, but the component that struts the stenosis is primarily the expandable stent-graft body. The main function of the hydrogel coating is to increase the biocompatibility of the stent surface and to increase the conformity with the implanted vessel wall, rather than to resist ureteral stenosis. However, the present solution still has the following technical problems:

the expandable stent graft is not stably positioned in the ureter due to the overall cylindrical shape, and the stent graft can be displaced to different degrees after operation, and once the displacement occurs, the position adjustment is very difficult. Meanwhile, the thickness of the expandable stent graft body is uniform, the thickness of the hydrogel coating is uniform, the inner diameter of the narrow part of the ureter is generally gradually changed, when the hydrogel coating expands, the gel coating generates larger depression at the narrow part of the ureter because the pressure of the narrow part of the ureter to the gel coating is larger than that of other parts, and the inner diameter of the narrow part corresponding to the original ureter is still smaller than that of the other parts after the new ureter inner wall is grown and the stent is taken out, so that the treatment effect is influenced.

Disclosure of Invention

The invention aims to solve the technical problem that the inner diameter of the narrow part corresponding to the original ureter is smaller than that of the other parts after the ureter bracket is used in the prior art, and provides a novel ureter bracket.

The invention solves the technical problem by the following modes:

a ureteral stent comprises a stent body and an expandable coating arranged on the outer surface of the stent body, wherein the thickness of the expandable coating corresponding to the narrow part of the ureter is larger than that of the expandable coating at the rest part. With the structure, the expandable coating can better resist the compression force of a narrow part of the ureter, so that the ureter after treatment has a more uniform inner diameter and better treatment effect.

As a preferred embodiment of the invention, the thickness of the expandable coating gradually increases from both ends to the middle, which is suitable for the ureter with a narrow part with a gradually reduced inner diameter, or the expandable coating comprises an axial uniform section and gradually-reduced sections at both ends of the axial uniform section. Such a structure is suitable for use in ureters having an axially uniform internal diameter narrowing.

In a preferred embodiment of the present invention, the stent body is provided with a plurality of segments of the expandable coating layer in an axially continuous or non-continuous manner. Such a structure can be applied to a ureter having multiple strictures.

As a preferred embodiment of the present invention, the expandable coating has a flow guide line on an outer surface thereof, and/or an anti-slip line on an inner surface thereof. This water conservancy diversion line can carry out the drainage to urine and calculus, and this anti-skidding line can strengthen and support the frictional force between the body, avoids expandable coating to peel off.

In a preferred embodiment of the present invention, the stent body is a non-expandable hollow tubular shape, and drainage holes and openings larger than the drainage holes are formed on the outer surface of the stent body. In the present invention, the non-expandable means that the stent body does not change its outer diameter after implantation. The drainage hole is used for draining urine and calculi, and the opening hole is used for discharging calculi with larger diameter to the outside of the body so as to avoid blockage in the ureter.

In a preferred embodiment of the present invention, the diameter of the drainage hole is 0.1mm to 1.7mm, and the diameter of the opening is 0.3mm to 2.5 mm.

As a preferred embodiment of the present invention, the stent body has a stopper portion for restricting axial movement of the expandable coating at a position corresponding to an end of the expandable coating.

In a preferred embodiment of the present invention, the position-limiting portion is a protrusion circumferentially provided on the outer surface of the stent body, and a circumferential outer diameter of the protrusion is smaller than or equal to a maximum outer diameter of the expandable coating after expansion.

As a preferred embodiment of the invention, the protrusion is funnel-shaped, the end of the expandable coating being arranged facing the funnel surface of the protrusion. With such a structure, peeling of the expandable coating from the stent body can be better avoided.

In a preferred embodiment of the present invention, the protrusion is a boss or a thin sheet.

In a preferred embodiment of the present invention, the axial end of the stent body has a detent portion for restricting the movement of the stent body. The screens are respectively arranged in the renal pelvis and/or the bladder to play a role in limiting the stent body.

In a preferred embodiment of the present invention, the peel resistance between the expandable coating and the stent body is 0.5N-15N.

In a preferred embodiment of the invention, the expandable coating is a material which can expand when meeting liquid, and the initial thickness of the expandable coating is 0.01mm-2mm, and the thickness after expansion is 0.03mm-8 mm.

In conclusion, the positive progress effects of the invention are as follows:

1. the ureteral stent provided by the invention adopts a structure of superposing the stent body and the expandable coating, and the thickness of the expandable coating corresponding to the narrow part of the ureter is thicker than that of other parts, so that the expandable coating can better resist the compression force of the narrow part of the ureter, the ureter after treatment has a more uniform inner diameter, and the treatment effect is better.

2. The self-expanding expandable coating is adopted, the implantation is convenient, the expandable coating can be well attached to the inner wall of the ureter after expansion, enough supporting force can be kept before ureter stenosis repair, and the displacement is not easy to occur. The expandable coating is soft in texture, does not damage the ureter, and can reduce discomfort.

3. When the thickness of the expandable coating corresponding to the narrow part of the ureter is positioned in the middle of the expandable coating, the thickness of the expandable coating gradually increases from two ends to the middle or the thickness gradually increases from two ends to the middle to a certain value and then extends to the middle with uniform thickness, so that the treated ureter has more uniform inner diameter and better treatment effect.

4. The stent body is provided with a plurality of segments of the expandable coating along the axial direction continuously or discontinuously, and can be suitable for the ureter with a plurality of narrow parts.

5. The outer surface of the expandable coating is provided with flow guide lines, and/or the inner surface of the expandable coating is provided with anti-skid lines. This water conservancy diversion line can carry out the drainage to urine and calculus, and this anti-skidding line can strengthen and support the body between frictional force, avoid expandable coating to peel off from the support body. The expandable coating is made of materials with good biocompatibility, such as gel, and the like, so that the endothelialization of the ureter at the position of the ureter stent can be realized in a reasonable period, and the occurrence of complications is reduced.

6. The support body is hollow tubular, be equipped with the drainage hole on the surface of support body and than the trompil that the drainage hole is bigger. The drainage hole can be used for draining urine and calculi, and the opening is used for discharging calculi with larger diameter to the outside of the body and avoiding blockage in the ureter.

7. The adjacent part of the bracket body and the end part of the expandable coating is provided with a limiting part for limiting the expandable coating to move towards the limiting part. The limiting part can prevent the expandable coating from being stripped from the bracket body.

8. At least one axial end of the support body is provided with a clamping part to limit the support body to move towards the clamping part. The clamping part can be arranged in the renal pelvis or the bladder, so that the limiting effect on the bracket body is achieved, and the bracket body is prevented from moving.

Drawings

The invention will be further described with reference to the accompanying drawings in which:

FIG. 1 is a diagram of a ureteral stent with the swellable coating at the lower segment;

FIG. 2 is a diagram of a ureteral stent with the swellable coating in the midsection;

FIG. 3 is a diagram of a ureteral stent with an expandable coating at the superior section;

FIG. 4 is an embodiment employing a non-uniform thickness expandable coating;

FIG. 5 is another embodiment employing an expandable coating of non-uniform thickness;

FIG. 6 is a perspective view of the drainage apertures and openings;

FIG. 7 is a view of a boss arrangement;

FIG. 8 shows another arrangement of bosses;

FIG. 9 shows yet another arrangement of bosses;

FIG. 10 is a schematic view of Experimental example 1;

FIG. 11 is a schematic view of Experimental example 2;

reference numerals and descriptions:

bracket body 100

Drainage hole 110

Opening 120

Clamping part 140

Expandable coating 200

Protrusion 210

Place frock 300

Annular stand 310

Pulling plate 320

Tooling fixture 400

Inner space 410

Through-hole 420

Computer type tension tester 500

Detailed Description

The invention is further illustrated by the following specific examples:

as shown in fig. 1 to 3, a ureteral stent comprises a stent body 100 and an expandable coating 200, wherein the stent body 100 is a non-expandable stent, the non-expandable refers to the condition that the outer diameter of the stent body 100 does not change after being implanted, the expandable coating 200 is arranged around at least one part of the outer surface of the stent body 100, and the expandable coating 200 can expand after absorbing body fluid of a human body to expand a ureter, thereby playing a role in treating ureteral stenosis.

The swellable coating 200 is located at any one or more of the outer surfaces of the stent body 100, which may be an upper, middle or lower portion of the stent body 100, depending on the location of the patient ureteral stenosis.

The expandable coating 200 may be either uniform or non-uniform in thickness.

In embodiments where the swellable coating 200 is non-uniform in thickness, as shown in fig. 4 and 5, the thickness of the swellable coating 200 is greater at the location of the ureteral stenosis than at the remaining portions of the ureteral. With such a structure, the expandable coating 200 corresponding to the narrow part of the ureter can better resist the compression force of the narrow part of the ureter, so that the treated ureter has a more uniform inner diameter and better treatment effect.

In some embodiments, the expandable coating 200 increases in thickness from end to end, which is suitable for use in a ureter having a narrowed portion with a tapered inner diameter, as shown in fig. 4. In an alternative embodiment, swellable coating 200 includes a central axially uniform segment and tapered segments disposed at opposite ends of the axially uniform segment. The axial sections correspond to the narrow parts of the ureters, and the structure is suitable for the ureters with the narrow parts with the axially uniform inner diameters.

In other embodiments, as shown in FIG. 5, the stent body 100 is provided with multiple segments of expandable coating 200 along the axial direction, either continuously or discontinuously. Such a structure can be applied to a ureter having multiple strictures.

Note that the above thickness refers to the thickness in the radial direction of the stent. Of course, it is also possible to use a ureter having a non-uniform thickness in the radial direction, depending on the actual shape of the patient ureter.

The expandable coating 200 is a material that is expandable upon exposure to a liquid. The material capable of expanding in the presence of liquid is a material capable of expanding in the presence of body fluid or water, such as hydrogel material, and can be selected from polyvinyl alcohol, polyethylene glycol dimethacrylate, poly (ethylene glycol) diacrylate, hydroxyethyl methacrylate, polyoxyethylene-polyoxypropylene-polyoxyethylene, polyurethane, polyvinylpyrrolidone, vinylpyrrolidone-acrylic acid copolymer, polyacrylamide, polyvinyl caprolactam, polyacrylate, polyamino acid, carboxymethyl cellulose, polymethyl acrylate, alginate, polyhydroxyethyl methyl acrylate, acrylamide, polyacrylic acid, hydrolyzed polyacrylonitrile, polyethyleneimine, ethoxylated polyethyleneimine polyallylamine, hyaluronic acid, methacrylated hyaluronic acid, chitosan, collagen, gelatin, fibrin, collagen, and polyvinyl pyrrolidone, polyvinylpyrrolidone, or a copolymer thereof, One or more of dextran and agarose.

The gel material has good elasticity, can be well attached to the inner wall of the ureter, so that the expandable coating 200 can be stably supported at the narrow section of the ureter and is not easy to displace; and the gel material is soft, can contact the inner wall of the ureter softly, is not easy to cause the damage of the inner wall of the ureter, and can reduce the uncomfortable feeling of patients.

The expandable coating 200 has a thickness of 0.01mm to 2mm in an initial state (i.e., a dry state) and a thickness of 0.03mm to 8mm after expansion upon absorption of liquid.

In use, the ureteral stent with the expandable coating 200 in a dry state is implanted into a ureter, and because the stent has a small outer diameter, the stent can be conveniently moved to a designated position in the ureter without causing damage to the patient ureter. After being implanted to a designated location, the expandable coating 200 absorbs body fluid and expands to a predetermined diameter, thereby expanding the narrowed section of the ureter to achieve the effect of preventing or treating ureteral stenosis.

As shown in fig. 6, the stent body 100 is hollow and tubular, a plurality of drainage holes 110 are uniformly arranged on the outer surface of the stent body 100, and after the expandable coating 200 is expanded and the ureter is blocked, urine can enter the stent body 100 through the drainage holes 110 and can be discharged out of the body, thereby draining the urine.

After the ureter is blocked by the expandable coating 200, urine in the ureter can be detained at the end position of the expandable coating 200, calculus is easily generated at the position, because the diameter of the calculus is large, the calculus is not easy to enter the stent body 100 through the drainage hole 110 and is discharged out of the body, and therefore after the stent is implanted for a period of time, the calculus can be continuously accumulated, and the problem of urinary tract blockage is caused.

It should be noted that the outer opening 120 (i.e., the opening near the urethra) is not limited to the end of the expandable coating 200, and may be disposed at any position on the outer surface of the stent body 100, as long as the stones entering the stent body 100 can be discharged.

Specifically, the diameter of the drainage hole 110 of the stent body 100 is 0.1mm to 1.7mm, and the diameter of the opening 120 is 0.3mm to 2.5 mm. By adopting the structure, the drainage effect of the bracket body 100 on urine and calculus can be ensured, the strength of the bracket body 100 can be ensured, and the bracket body 100 is prevented from being broken in use.

As shown in fig. 7, 8 and 9, the stent body 100 preferably has a position-limiting part for limiting the axial movement of the expandable coating at a position close to the end of the expandable coating 200, so as to keep the ureteral stent intact and avoid the stripped expandable coating 200 from remaining in the ureter, which causes urinary tract infection, obstruction or calculus.

Because the ureteral stent has a small outer diameter when implanted, the expandable coating 200 does not directly abut against the inner wall of the ureter, and the problem of peeling off of the expandable coating 200 is not likely to occur. When the ureteral stent is taken out, the expanded expandable coating 200 is abutted against the inner wall of the ureter, and the problem that the expandable coating 200 is easily peeled off when the ureteral stent can be taken out by overcoming the friction force between the expandable coating 200 and the inner wall of the ureter.

Thus, in some embodiments, a stop may be provided only at the lower end of the expandable coating 200 (i.e., the end near the bladder) for stopping the expandable coating 200 during removal of the stent, which substantially overcomes the peeling problem of the expandable coating 200 and reduces the production cost. Of course, the present invention preferably employs a structure in which the expandable coating layer 200 is provided at both ends thereof with stoppers, so as to prevent the expandable coating layer 200 from being peeled off to the maximum.

The limiting portion is a protrusion 210 disposed around the outer surface of the holder body 100. The circumferential outer diameter of the protrusion 210 is less than or equal to the maximum outer diameter of the expandable coating 200 after expansion to avoid obstructing implantation and removal of the ureteral stent. The protrusion 210 may be a boss, a sheet, or the like.

Preferably, as shown in fig. 7, the protrusion 210 may also have a funnel shape, and the end of the expandable coating 200 is disposed facing the funnel surface of the protrusion 210. With this structure, the end of the expandable coating 200 can be attached to the inner surface of the protrusion 210 (i.e., the concave funnel surface), which can better prevent the expandable coating 200 from peeling off.

The holder body 100 has a stopper portion at an axial end thereof for restricting movement of the holder body. The clamping part can be in a winding disc shape, a winding ball shape and the like, and can have any shape which can play a limiting role in the renal pelvis and the bladder. In this embodiment, the positioning portion is provided with positioning portions 140 with opposite winding directions, the positioning portions 140 may be in a shape of a winding disc shape, a winding ball shape, or the like, which can limit the renal pelvis and the bladder, and after the stent is mounted, the positioning portions 140 at both ends are respectively placed in the renal pelvis and the bladder, thereby limiting the stent. Preferably, the blocking portion 140 has a hollow tubular structure and is integrally connected to the stent body 100, and the blocking portion 140 is also provided with drainage holes 110 to improve the drainage of urine.

The stent body 100 is made of a polymer material, which may be polyurethane or silicone rubber, and the radial supporting force thereof is 0.5N-20N. The length of the stent body 100 is 5cm-40 cm. The length of the stent body 100 in actual use depends on the length of the ureter of a patient.

The expandable coating 200 is applied to the surface of the stent body 100 by one or more of spraying, brushing, die filling, dipping, rolling, spin coating, molding, electrodeposition, and vacuum vapor deposition, and is fixed to the surface of the stent body 100 by one or more of air oxidation curing, solvent evaporation curing, thermal or chemical reaction curing, radiation curing (including ultraviolet curing and electron beam curing), melt curing, and infrared catalytic thermal reaction curing, preferably by a photocuring method with high bonding strength. In the present invention, the peel resistance of expandable coating 200 is in the range of 0.5N to 15N.

The expandable coating 200 may have flow-directing texture on its outer surface and/or anti-slip texture on its inner surface, such as on the inner surface of the expandable coating 200. This water conservancy diversion line can carry out the drainage to urine and calculus, and this anti-skidding line can strengthen and support body 100 between frictional force, avoid expandable coating to peel off.

The ureteral stent of the invention is used as follows:

implanting the ureteral stent with the swellable coating 200 in a dry state into a corresponding location in the patient's ureter;

the expandable coating 200 expands to a designated thickness after absorbing body fluid, thereby expanding the stricture of the ureter;

after 28 days, a new ureteral inner wall is formed, and the ureteral stent is taken out, at which time the patient's narrow ureter has healed and reached a normal ureteral diameter.

This ureteral stent's advantage lies in:

5. The outer surface of the expandable coating is provided with diversion lines, and/or the inner surface of the expandable coating is provided with anti-skid lines. This water conservancy diversion line can carry out the drainage to urine and calculus, and this anti-skidding line can strengthen and support the body between frictional force, avoid expandable coating to peel off from the support body. The expandable coating is made of materials with good biocompatibility, such as gel, and the like, so that the endothelialization of the ureter at the position of the ureter stent can be realized in a reasonable period, and the occurrence of complications is reduced.

6. The support body is the cavity tubulose, is equipped with drainage hole and the bigger trompil than the drainage hole on the surface of support body. The drainage hole can be used for draining urine and calculi, and the opening is used for discharging calculi with larger diameter to the outside of the body and avoiding blockage in the ureter.

7. The adjacent part of the bracket body and the end part of the expandable coating is provided with a limiting part which limits the expandable coating to move towards the direction of the limiting part. The limiting part can prevent the expandable coating from being stripped from the bracket body.

8. At least one axial end of the bracket body is provided with a clamping part to limit the bracket body to move towards the clamping part. The clamping part can be arranged in the renal pelvis or the bladder, so that the limiting effect on the bracket body is achieved, and the bracket body is prevented from moving.

The effects of the present invention are further illustrated by the following experimental examples:

experimental example 1 (radial support force experiment):

purpose of the experiment:

when the ureter stent is used, the expandable coating expands when meeting liquid (such as water or urine) and has larger outer diameter than the focus of the ureter, thereby playing the role of resisting stenosis. During the use of the ureteral stent, the expandable coating of the ureteral stent is ensured not to be crushed by radial extrusion or the ureteral stent body is not deformed by extrusion. The purpose of this test is therefore to test the radial support force of the ureteral stent.

Experimental apparatus:

the experimental example employs a placing tool 300 as shown in fig. 10, where the placing tool 300 includes a pulling plate 320, and annular placing members 310 arranged at the edge of the pulling plate 320 at intervals for the stent body 100 to penetrate through.

The experimental steps are as follows:

sample preparation: fully soaking the ureteral stent in liquid (such as water or urine) until the diameter of the expandable coating expands to 100% (namely the diameter of the expandable coating does not change any more), wherein the soaking time is less than or equal to 29 days;

connecting the two pulling plates 320 for placing the tool 300 with the computer type tensile testing machine 500; the annular placing pieces 310 of the two pulling plates 320 of the placing tool 300 are arranged in a staggered mode, so that a tubular placing area for the stent body 100 to penetrate is formed;

placing the stent body 100, which expands after being immersed in a liquid (e.g., water or urine), in the placement area;

starting the computer type tensile testing machine 500 to adjust the relative position of the annular placing member 310 and the sample, wherein the annular placing member 310 is ensured to be in contact with the expandable coating part, but not to be extruded;

setting the movement displacement of the two pull plates 320 to be 0.5mm (which is equivalent to the compression deformation amount of 0.5mm), driving the two pull plates 320 of the placing tool 300 to move in opposite directions by the computer type tension tester 500, automatically stopping the computer type tension tester 500 after the two pull plates 320 of the placing tool 300 move by 0.5mm, observing whether the expandable coating is intact and whether the support body is intact and undeformed in the process, and recording the maximum force value in the process;

and (3) setting the movement displacement to be 1mm, 1.5mm, 2mm, 2.5mm, 3mm and 4mm in sequence, repeating the steps, and recording the maximum force value in the process, namely the radial supporting force of the ureteral stent.

The experimental results are as follows:

the amount of compressive deformation is related to the radial support force, and the obtained experimental data are shown in table 1:

TABLE 1

As can be seen from Table 1, the expandable coating after expansion is not broken and damaged under various compressive deformation amounts, and the stent body is not deformed and remains intact. The radial support force of the ureters with expandable coatings ranges from 0.5N to 20N.

The ureteral stent should be subjected to a radial pressure during use that does not exceed this radial support force, thereby ensuring that the expandable coating and the stent body are unbroken and undeformed.

Experimental example 2 (peel resistance experiment):

purpose of the experiment:

the expandable coating expands after the ureteral stent with the expandable coating is soaked in liquid (such as water or urine), and after the ureteral stent is inserted, the expandable coating plays a role in resisting stenosis due to expansion. However, after the ureteral stent is used, the ureteral stent with the expandable coating needs to be taken out of a human ureter.

The expandable coating cannot break and fall out of the ureteral stent body throughout the entire removal process to ensure the safety and effectiveness of the ureteral stent. This test was therefore used to test the peel resistance of the ureteral stent required for the narrower channels to cause the detachment or rupture of the expandable coating during passage through the simulated human ureter.

Experimental apparatus:

the test adopts the tooling device 400 shown in fig. 11, the tooling device 400 has a hollow inner space 410 therein, the top of the tooling device 400 has a through hole 420 communicated with the outside, and the through hole 420 is designed to ensure that the bracket body of the test sample just freely passes through. The tooling device 400 is arranged below the computer type tensile testing machine 500 and can be fixed on the computer type tensile testing machine 500, so that the condition that the accuracy of a detection result is influenced by the movement of the tooling device 400 and the like in the detection process is avoided.

The experimental steps are as follows:

sample preparation: putting the ureteral stent into liquid (such as water or urine) to be soaked until the diameter of the expandable coating expands to 100 percent, wherein the soaking time is less than or equal to 29 days, and then taking out;

the bracket body 100 penetrates through the through hole 420 from bottom to top, the part of the bracket body 100 without the expandable coating penetrates through the upper end part of the through hole 420, the computer type tensile testing machine 500 is connected with the bracket body 100 and fixed, the position of a sample is finely adjusted, and the expandable coating is ensured to be partially positioned in the hollow inner space 410 of the tool 400;

and starting the computer type tensile testing machine 500, pulling the bracket body 100 out of the through hole 420 by the computer type tensile testing machine 500 at a speed of 300mm/min, and recording that the maximum force of the computer type tensile testing machine 500 in the process is the peeling resistance of the expandable coating after the test is finished when the expandable coating is completely pulled out of the tool 400.

The experimental results are as follows:

the results of the experiment are shown in table 2:

TABLE 2

Experimental proceduresNumber (C)	1	2	3
				Resistance to peeling	1.442N	1.255N	1.412N

When the expanded expandable coating is partially stripped, the whole expandable coating is completely stripped, and no residual expandable coating is left on the stent body. The ureteral stent should be subjected to no more than this peel resistance during use, so as to ensure that the expandable coating does not peel away from the stent.

The tool 400 in the experiment is made of a rigid material, the friction force between the through hole 420 and the ureteral stent is relatively small, and the ureteral stent can easily penetrate through the through hole 420, so that the peeling resistance measured in the experiment is relatively small. If the through hole 420 is replaced by a flexible channel simulating a ureter, the friction force between the channel and the ureteral stent is increased, the ureteral stent is difficult to pass through the channel, and therefore the peeling resistance measured by experiments is increased. Through a plurality of experiments, the experimental result shows that the peel resistance between the expandable coating and the stent body is in the range of 0.5N-15N.

However, those skilled in the art should recognize that the above-described embodiments are illustrative only and not limiting, and that changes and modifications to the above-described embodiments are intended to be included within the scope of the appended claims.

Claims

1. A ureteral stent comprises a stent body and an expandable coating arranged on the outer surface of the stent body, and is characterized in that: the thickness of the expandable coating corresponding to the narrow part of the ureter is larger than that of the expandable coating of the rest part.

2. The ureteral stent according to claim 1, wherein: the thickness of the expandable coating is gradually increased from two ends to the middle, or the expandable coating comprises an axial uniform section and gradually-reduced sections positioned at two ends of the axial uniform section.

3. The ureteral stent according to claim 1, wherein: the stent body is provided with a plurality of sections of the expandable coating continuously or discontinuously along the axial direction.

4. A ureteral stent according to any of claims 1 to 3, wherein: the outer surface of the expandable coating is provided with flow guide lines, and/or the inner surface of the expandable coating is provided with anti-skid lines.

5. The ureteral stent according to claim 1, wherein: the stent body is in a non-expandable hollow tubular shape, and the outer surface of the stent body is provided with drainage holes and openings larger than the drainage holes.

6. The ureteral stent according to claim 5, wherein: the diameter of the drainage hole is 0.1mm-1.7mm, and the diameter of the opening is 0.3mm-2.5 mm.

7. The ureteral stent according to claim 1, wherein: the stent body is provided with a limiting part for limiting the axial movement of the expandable coating at the position corresponding to the end part of the expandable coating.

8. The ureteral stent of claim 7, wherein: the limiting part is a protruding part circumferentially arranged on the outer surface of the bracket body, and the circumferential outer diameter of the protruding part is smaller than or equal to the maximum outer diameter of the expanded expandable coating.

9. The ureteral stent according to claim 8, wherein: the protrusion is funnel-shaped, with an end of the expandable coating disposed facing the funnel surface of the protrusion.

10. The ureteral stent according to claim 8, wherein: the protruding part is a boss or a thin sheet.

11. The ureteral stent of claim 1, wherein: the axial end of the bracket body is provided with a clamping part for limiting the movement of the bracket body.

12. The ureteral stent of claim 1, wherein: the peel resistance between the expandable coating and the stent body is 0.5N-15N.

13. The ureteral stent of any of claims 1 to 3,5 to 12, wherein: the expandable coating is a material which can expand when meeting liquid, the initial thickness of the expandable coating is 0.01mm-2mm, and the thickness after expansion is 0.03mm-8 mm.