CN116019602A

CN116019602A - Ureteral stent

Info

Publication number: CN116019602A
Application number: CN202211668040.4A
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: 2023-04-28
Also published as: CN113599018A; WO2023001302A1; CN115813604A

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 the narrow part of a ureter is larger than that of the expandable coating of the rest part. By adopting the structure, the inflatable coating can better resist the pressing force of the narrow part of the ureter, so that the ureter after treatment has a more uniform inner diameter and better treatment effect.

Description

Ureteral stent

The invention is a division of Chinese patent application (application number: CN 202110838209.5) with application date of 2021, 7, 23.

Technical Field

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

Background

Ureteral stenosis is not uncommon in clinic, and secondary ureteral stenosis is mainly caused by iatrogenic stenosis, stone incarceration, infection, endometriosis, retroperitoneal fibrosis, malignant tumor, radiotherapy and the like, except congenital stenosis.

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 recurrence and the like. With the development of the endoscope technology, the ureteral stenotic endoluminal surgical treatment is gradually popularized, and a ureteral balloon under the endoscope or a ureteral stenotic endotomy is first selected, so that a ureteral stent is needed to be placed after the operation to prevent the recurrence of the stenoses. At present, the double J-tube commonly used in clinic has the defects of discomfort after tube placement, stent skin formation, even stone generation induction, periodic replacement and the like. In recent years, the metal stent is applied to clinic, has the advantages of biocompatibility, flexibility and corrosion resistance, but still cannot be permanently placed in a body, has a plurality of complications, is particularly easy to shift, and greatly reduces the cure rate of ureteral stenosis.

The metal stent is mainly ResonanceTM produced by COOK company in the United states and Silhouette TM produced by APPLIED medical company, the spiral coil design simultaneously increases the tensile strength and stability, the retention time of the metal stent is greatly prolonged, complications are less than those of double J tubes, the treatment effect on ureteral stenosis caused by malignant tumor is better, and the problems of stent obstruction, discomfort of patients, urinary tract infection and the like still exist. In recent years, new metal stents have been developed which do not cover the full length of the ureter, but only for stenosed ureters, also known as inflatable metal ureteral stents, and can be classified into self-expanding and balloon-expanding according to the mechanism of expansion. Balloon expansion is clinically limited in its application due to the presence of obstructive urothelial hyperplasia reactions, and therefore clinically expandable metal ureteral stents are often referred to as self-expanding metal stents. The first expandable metal ureteral stent is a Wallstent manufactured by Boston science, and is a wire mesh made of stainless steel, which can be placed either in an anterograde or in a retrograde manner. Although it is unavoidable that tumor growth presses the stent or even blocks, the stent patency can be as high as 54%. The disadvantage is that it was not originally designed for ureters and thus stent removal is difficult.

While expandable metal ureteral stents have many advantages over conventional double J-tubes, too many complications limit their wide clinical use. Early stent-related adverse reactions include iatrogenic injury, stent migration and patient discomfort, and late stent-related complications include infection and stent replacement difficulties, hardware failure, and stent fouling. In rare cases, prolonged stent placement can lead to ureteral arterial fistulae and iliac vascular erosion. In addition, there is no random clinical trial and long-term follow-up observation of the therapeutic effects of expandable metal ureteral stents in bulk cases nor clinical data comparing the therapeutic effects of various stents. At the same time, it was found that the post-operative stent was displaced to varying degrees, and once displaced, it was very difficult to adjust the position. In addition, once the stent is output, if it is improperly placed and cannot be recovered, the psychological burden of the surgeon and the economical burden of the patient are increased.

US 2012/0123327 A1 discloses a ureteral stent comprising a reticulated metal-based expandable stent body and a hydrogel coating provided on the outer surface of the stent body, which can expand slightly after being immersed in a liquid, but the means to distract the stricture is mainly the expandable stent body. The hydrogel coating has the main function of increasing the biocompatibility of the stent surface and the fitting property with the implanted tube wall, but not the ureteral stenosis resistance. However, the following technical problems still exist in the present solution:

the inflatable covered stent cannot be stably positioned in the ureter due to the shape of a cylinder as a whole, the postoperative stent can be displaced to different degrees, and the position is difficult to adjust once the postoperative stent is displaced. Meanwhile, the thickness of the expandable covered stent body is uniform, the thickness of the hydrogel coating is also 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 concave parts because the pressing force of the narrow part of the ureter to the gel coating is larger than the pressing force of other parts to the gel coating, and after a new ureter inner wall grows and a stent is taken out, the inner diameter corresponding to the narrow part of the original ureter is still smaller than the other parts, so that the treatment effect is influenced.

Disclosure of Invention

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

The invention solves the technical problems by the following steps:

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 a ureter is larger than that of the expandable coating of the rest part. By adopting the structure, the inflatable coating can better resist the compression force of the 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 present invention, the thickness of the expandable coating is gradually increased from both ends to the middle, and such a structure is suitable for a ureter having a tapered narrow portion of an inner diameter, or the expandable coating includes an axially uniform section and tapered sections at both ends of the axially uniform section. This structure is suitable for ureters having an axially uniform inner diameter stenosis.

As a preferred embodiment of the present invention, the stent body is provided with a plurality of segments of the expandable coating continuously or discontinuously in the axial direction. This structure can be applied to ureters having a plurality of stenoses.

As a preferred embodiment of the present invention, the outer surface of the expandable coating is provided with a flow guiding pattern, and/or the inner surface of the expandable coating is provided with an anti-slip pattern. The urine and calculus can be drained through the diversion lines, the friction force between the anti-slip lines and the support body can be enhanced, and the expandable coating is prevented from being stripped.

As a preferred embodiment of the present invention, the stent body is a non-inflatable hollow tube, and the outer surface of the stent body is provided with a drainage hole and an opening larger than the drainage hole. In the present invention, the non-expansibility means that the stent body does not change its outer diameter after implantation. The drainage hole has the functions of draining urine and stones, and the opening has the function of discharging stones with larger diameters to the outside of the body so as to avoid blockage in the ureter.

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

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

As a preferred embodiment of the present invention, the limiting portion is a protrusion portion on the outer surface of the stent body Zhou Sheyu, and the circumferential outer diameter of the protrusion portion is smaller than or equal to the maximum outer diameter of the expandable coating after expansion.

As a preferred embodiment of the invention, the protrusions are funnel-shaped, and the ends of the expandable coating are arranged facing the funnel surface of the protrusions. With such a structure, the expandable coating can be better prevented from peeling off the stent body.

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

As a preferred embodiment of the present invention, the axial end of the holder body has a stopper for restricting the movement of the holder body. The clamping positions are respectively arranged in the renal pelvis and/or the bladder to play a limiting role on the bracket body.

As a preferred embodiment of the present invention, the peel resistance between the expandable coating and the stent body is in the range of 0.5N to 15N.

As a preferred embodiment of the invention, the expandable coating is a liquid-expandable material, the initial thickness of the expandable coating is 0.01mm-2mm, and the thickness after expansion is 0.03mm-8mm.

The invention has the following positive progress effects:

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

2. The self-expansion expandable coating is convenient to implant, the expandable coating can be well attached to the inner wall of the ureter after being expanded, and enough supporting force can be kept before ureter stenosis is repaired, so that the expandable coating is not easy to shift. 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 gradually increases to a certain value from two ends to the middle and then extends to the middle with uniform thickness, so that the ureter after treatment has a more uniform inner diameter and better treatment effect.

4. The stent body is provided with a plurality of sections of the expandable coating continuously or discontinuously along the axial direction, so that the stent can be suitable for ureters with a plurality of narrow parts.

5. The outer surface of the expandable coating is provided with guide lines, and/or the inner surface of the expandable coating is provided with anti-skid lines. The urine and calculus can be drained through the diversion lines, the friction force between the anti-slip lines and the support body can be enhanced, and the expandable coating is prevented from being stripped from the support body. The expandable coating is mostly made of gel and other materials with good biocompatibility, so that endothelialization of ureter at 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 drainage hole and than drainage hole bigger trompil on the surface of support body. The drainage hole can be used for draining urine and stones, and the hole is used for discharging stones with larger diameters to the outside of the body, so that blockage in the ureter is avoided.

7. The support body is provided with a limiting part adjacent to the end part of the expandable coating, and the expandable coating is limited 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 bracket body is provided with a clamping part so as to limit the bracket body to move towards the clamping part. The clamping part can be placed in the renal pelvis or the bladder to play a limiting role on the bracket body and prevent the bracket body from moving.

Drawings

The invention is further described below with reference to the accompanying drawings:

fig. 1 is a diagram of a ureteral stent with an expandable coating in the lower section;

fig. 2 is a diagram of a ureteral stent with an expandable coating in the middle section;

fig. 3 is a diagram of a ureteral stent with an expandable coating in the upper section;

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

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

FIG. 6 is a perspective view of a drainage aperture and opening;

FIG. 7 is a boss arrangement;

FIG. 8 is an alternative arrangement of bosses;

FIG. 9 is yet another arrangement of bosses;

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

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

reference numerals and description:

bracket body 100

Drainage aperture 110

Opening 120

Clamping portion 140

Expandable coating 200

Protrusion 210

Placement tool 300

Annular placement member 310

Pulling plate 320

Tool 400

Interior space 410

Through hole 420

Computer type tensile testing machine 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-expansion means that the outer diameter of the stent body 100 is not changed after implantation, the expandable coating 200 is annularly arranged on 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 expandable coating 200 is located at any one or more of the outer surfaces of the stent body 100, either the upper, middle or lower portion of the stent body 100, depending on the location of the patient ureteral stenosis.

The thickness of the expandable coating 200 may be uniform or non-uniform.

As shown in fig. 4 and 5, in embodiments in which the thickness of the expandable coating 200 is non-uniform, the thickness of the expandable coating 200 corresponding to a stenosis of the ureter is greater than the thickness of the expandable coating 200 corresponding to the remainder of the ureter. By adopting the structure, the expandable coating 200 corresponding to the ureteral stenosis can better resist the compression force of the ureteral stenosis, so that the ureter after treatment has a more uniform inner diameter and the treatment effect is better.

As shown in fig. 4, in some embodiments, the thickness of the expandable coating 200 increases gradually from the ends to the middle, and such a structure is suitable for ureters having a tapered inner diameter stenosis. In an alternative embodiment, the expandable coating 200 includes an axially uniform section in the middle and tapered sections disposed at either end of the axially uniform section. The axially uniform segment corresponds to a stricture of the ureter, and the structure is applicable to a ureter having an axially uniform inner diameter stricture.

In other embodiments, as shown in fig. 5, the stent body 100 is provided with multiple segments of expandable coating 200 in the axial direction, which may be continuous or discontinuous. This structure can be applied to ureters having a plurality of stenoses.

The thickness mentioned above refers to the thickness in the radial direction of the stent. Of course, ureters of non-uniform thickness in the radial direction may also be used depending on the actual shape of the patient ureter.

The expandable coating 200 is a liquid-swellable material. The liquid-swellable material is a material that swells when encountering body fluid or water, such as hydrogel material, and is selected from one or more of polyvinyl alcohol, polyethylene glycol dimethacrylate, poly (ethylene glycol) diacrylate, hydroxyethyl methacrylate, polyethylene oxide-polypropylene oxide-polyethylene oxide, polyurethane, polyvinylpyrrolidone, vinylpyrrolidone-acrylic acid copolymer, polyacrylamide, polyvinylcaprolactam, 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, dextran, and agarose.

The gel material has good elastic force, 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 shift; and gel material is soft, can gently contact the inner wall of the ureter, is difficult to cause the inner wall injury of the ureter, and can reduce the uncomfortable feeling of patients.

The thickness of the expandable coating 200 in the initial state (i.e., dry state) is 0.01mm-2mm and the thickness after liquid absorption expansion is 0.03mm-8mm.

When the ureteral stent with the expandable coating 200 in a dry state is implanted into a ureter, the ureteral stent can be conveniently moved to a designated position in the ureter due to the smaller outer diameter of the stent, so that the ureter is not easy to be damaged. After implantation to a designated location, the swellable coating 200 absorbs body fluids and expands to a predetermined diameter, thereby expanding the stenosed region of the ureter and achieving the effect of preventing or treating ureteral stenosis.

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

When the expandable coating 200 seals the ureter, urine in the ureter is retained at the end position of the expandable coating 200, stones are easily generated at the position, and the stones are not easy to enter the stent body 100 through the drainage holes 110 and are discharged outside, so that the stones are accumulated continuously after the stent is implanted for a period of time, and the problem of blockage of the urinary tract is caused.

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

Specifically, the diameter of the drainage hole 110 of the stent body 100 is 0.1mm-1.7mm, and the diameter of the opening 120 is 0.3mm-2.5mm. By adopting the structure, the drainage effect of the bracket body 100 on urine and stones 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, it is preferable that the stent body 100 has a stopper for limiting the axial movement of the expandable coating at a position near the end of the expandable coating 200, for keeping the ureteral stent intact, and preventing the peeled expandable coating 200 from remaining in the ureter, resulting in urinary tract infection, blockage or occurrence of stones.

Because the ureteral stent has smaller outer diameter when being implanted, the expandable coating 200 is not directly propped against the inner wall of the ureter, and the problem of peeling of the expandable coating 200 is not easy to occur. When the ureteral stent is taken out, the expanded expandable coating 200 is propped against the inner wall of the ureter, the ureteral stent needs to be taken out by overcoming the friction force between the expandable coating 200 and the inner wall of the ureter, and the problem that the expandable coating 200 is easily peeled off occurs at the moment.

Thus, in some embodiments, a stop may be provided only at the lower end of the expandable coating 200 (i.e., the end adjacent to the bladder), which is used only to stop the expandable coating 200 when the stent is removed, thereby substantially overcoming the peeling problem of the expandable coating 200 and reducing the production cost. Of course, the present invention preferably adopts a structure in which the limiting portions are provided at both ends of the expandable coating 200, so as to maximally avoid the occurrence of peeling of the expandable coating 200.

The limiting portion is a protrusion 210 on the outer surface of the Zhou Sheyu stent 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 impeding implantation and removal of the ureteral stent. The protrusion 210 may be a boss, a tab, or the like.

Preferably, as shown in fig. 7, the protrusion 210 may also be funnel-shaped, with the end of the expandable coating 200 facing the funnel face of the protrusion 210. With such a structure, the end portion of the expandable coating layer 200 and the inner surface of the protrusion 210 (i.e., the concave funnel surface) can be bonded to each other, and the expandable coating layer 200 can be prevented from peeling off.

The axial end of the holder body 100 has a stopper for restricting the movement of the holder body. The detents may be in any shape that can act as a stop in the renal pelvis and bladder, such as a coiled disc. In this embodiment, the clamping portions 140 with opposite winding directions are provided, the clamping portions 140 may be in a shape of a winding disc, a winding sphere or the like, which can play a role in limiting the renal pelvis and the bladder, and after the stent is installed, the clamping portions 140 at two ends are respectively placed in the renal pelvis and the bladder, thereby limiting the stent. Preferably, the clamping portion 140 is of a hollow tubular structure and integrally connected with the bracket body 100, and the clamping portion 140 is also provided with a drainage hole 110 to improve the urine drainage effect.

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

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

The outer surface of the expandable coating 200 is provided with flow directing lines and/or the inner surface of the expandable coating 200 is provided with anti-slip lines. The flow guide lines can drain urine and stones, and the anti-slip lines can enhance friction force between the anti-slip lines and the bracket body 100, so that the expandable coating is prevented from being stripped.

The ureteral stent of the invention is used in the following manner:

implanting the ureteral stent with the expandable coating 200 in a dry state in a corresponding location in a ureter of a patient;

the expandable coating 200 expands to a designated thickness after absorbing body fluid of a human body, thereby dilating a stenosed portion of the ureter;

after 28 days, a new ureteral inner wall was formed, the ureteral stent was removed, at which time the patient's stenosed ureter had healed and reached a normal ureter diameter.

The ureteral stent has the advantages that:

5. The outer surface of the expandable coating is provided with guide grains, and/or the inner surface of the expandable coating is provided with anti-skid grains. The urine and calculus can be drained through the diversion lines, the friction force between the anti-slip lines and the support body can be enhanced, and the expandable coating is prevented from being stripped from the support body. The expandable coating is mostly made of gel and other materials with good biocompatibility, so that endothelialization of ureter at the ureter stent can be realized in a reasonable period, and the occurrence of complications is reduced.

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

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

experimental example 1 (radial supporting force experiment):

the purpose of the experiment is as follows:

in the using process of the ureteral stent, the expandable coating expands after meeting liquid (such as water or urine), and the outer diameter of the expandable coating is larger than that of a focus part of a ureter, so that the ureteral stent has an anti-stenosis effect. During use of the ureteral stent, the expandable coating of the ureteral stent is not broken due to radial extrusion, or the ureteral stent body is not deformed due to extrusion. The aim of this test was therefore to test the radial support of ureteral stents.

The experimental device comprises:

the present experiment adopts a placement tool 300 as shown in fig. 10, where the placement tool 300 includes a pull plate 320 and annular placement members 310 which are arranged at the edge of the pull plate 320 at intervals and into which the bracket body 100 penetrates.

The experimental steps are as follows:

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

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

placing the stent body 100, which swells 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 positions of the annular placing member 310 and the sample, wherein the annular placing member 310 is ensured to be contacted with the expandable coating part, but not to be extruded;

setting the displacement of the two pulling plates 320 to be 0.5mm (equivalent to the compression deformation amount to be 0.5 mm), driving the two pulling plates 320 of the placing tool 300 to move in opposite directions by the computer type tensile testing machine 500, automatically stopping the computer type tensile testing machine 500 after the two pulling plates 320 of the placing tool 300 are moved by 0.5mm, observing whether the expandable coating is intact or not in the process, judging whether the bracket body is intact or not, and recording the maximum force value in the process;

the moving displacement is sequentially set to be 1mm, 1.5mm, 2mm, 2.5mm, 3mm and 4mm, the steps are repeated, and the maximum force value in the process, namely the radial supporting force of the ureteral stent, is recorded.

Experimental results:

the relationship between the compression deformation amount and the radial supporting force, and the obtained experimental data are shown in table 1:

TABLE 1

As can be seen from table 1, the expanded expandable coating was not broken or broken under each compression deformation, and the stent body was not deformed and remained intact. The radial support force of the ureter with the expandable coating ranges from 0.5N to 20N.

The radial pressure to which the ureteral stent is subjected during use should not exceed this radial supporting force, so as to ensure that the expandable coating and the stent body are not damaged or deformed.

Experimental example 2 (peel resistance test):

the purpose of the experiment is as follows:

the ureteral stent with the expandable coating swells after being immersed in a liquid (e.g., water or urine) and, after insertion into the ureter, the expandable coating acts as an anti-stenotic agent due to the swelling. But after the ureteral stent has been used, the ureteral stent with the expandable coating needs to be removed from the human ureter.

During the whole extraction process, the expandable coating cannot be broken and cannot fall off from the ureteral stent body, so that the safety and the effectiveness of the ureteral stent are ensured. Therefore, the test is used for detecting the stripping resistance required by the expansion coating falling off or breaking of the ureteral stent caused by a narrower channel in the process of simulating the human ureter.

The experimental device comprises:

the present experiment adopts a fixture 400 as shown in fig. 11, the fixture 400 has a hollow inner space 410, the top of the fixture 400 has a through hole 420 communicated with the outside, and the through hole 420 should ensure that the bracket body of the test sample just passes freely. The tool 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 affected due to the fact that the tool 400 moves in the detection process is avoided.

The experimental steps are as follows:

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

the bracket body 100 passes through the through hole 420 from bottom to top, so that the part of the bracket body 100 without the expandable coating passes 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 is fixed, the sample position is finely adjusted, and the expandable coating part is ensured to be positioned in the hollow inner space 410 of the tool 400;

starting the computer type tensile testing machine 500, starting the computer type tensile testing machine 500 to pull the bracket body 100 out of the through hole 420 at a speed of 300mm/min, and recording the maximum force of the computer type tensile testing machine 500 in the process as the peeling resistance of the expandable coating when the expandable coating part is completely pulled out of the tool device 400.

Experimental results:

the experimental results obtained are shown in table 2:

TABLE 2

The expanded expandable coating is peeled off completely and completely, and no residual expandable coating is left on the stent body. The ureteral stent should not be subjected to a tensile force exceeding this peel-resistant force during use, so as to ensure that the expandable coating does not peel off the stent.

The tool 400 of 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 easily passes through the through hole 420, so that the peeling resistance measured by the experiment is relatively small. If the through hole 420 is replaced with a flexible channel simulating the ureter, the friction between the channel and the ureteral stent is increased, the ureteral stent passes through the channel to be difficult, and thus the peeling resistance measured by experiments is increased. Experiments show that the range of the stripping resistance between the expandable coating and the stent body is 0.5N-15N.

However, it should be appreciated by those skilled in the art that the above embodiments are merely illustrative of the present invention and not intended to be limiting, and that changes and modifications to the above embodiments are intended to fall within the scope of the appended claims.

Claims

1. The utility model provides a ureteral stent, includes the support body and locates the expandable coating of support body surface, its characterized in that: the thickness of the expandable coating corresponding to the narrow part of the ureter is larger than that of the other parts, and the stent body is provided with a limiting part for limiting the axial movement of the expandable coating at a position corresponding to the end part of the expandable coating.

2. The ureteral stent according to claim 1, characterized in that: the thickness of the expandable coating gradually increases from two ends to the middle, or the expandable coating comprises an axial uniform section and gradually smaller sections positioned at two ends of the axial uniform section, and/or the stent body is provided with a plurality of sections of the expandable coating continuously or discontinuously along the axial direction.

3. The ureteral stent according to any of claims 1-2, characterized in that: the outer surface of the expandable coating is provided with guide lines, and/or the inner surface of the expandable coating is provided with anti-skid lines.

4. The ureteral stent according to claim 1, characterized in that: the support body is the hollow tubular of non-expansibility, be equipped with drainage hole and than the bigger trompil of drainage hole on the surface of support body.

5. The ureteral stent according to claim 4, characterized in that: the diameter of the drainage hole is 0.1mm-1.7mm, and the diameter of the opening is 0.3mm-2.5mm.

6. The ureteral stent according to claim 1, characterized in that: the limiting part is a protruding part on the outer surface of the bracket body Zhou Sheyu, and the circumferential outer diameter of the protruding part is smaller than or equal to the maximum outer diameter of the expandable coating after expansion.

7. The ureteral stent according to claim 6, characterized in that: the protrusions are funnel-shaped, the ends of the expandable coating are disposed towards the funnel face of the protrusions, and/or the protrusions are bosses or tabs.

8. The ureteral stent according to claim 1, characterized in that: the axial end of the support body is provided with a clamping part used for limiting the movement of the support body.

9. The ureteral stent according to claim 1, characterized in that: the peel resistance between the expandable coating and the stent body is 0.5N-15N.

10. The ureteral stent according to any of claims 1 to 2,4 to 9, characterized in that: the expandable coating is a material expandable when meeting liquid, the initial thickness of the expandable coating is 0.01mm-2mm, and the thickness after expansion is 0.03mm-8mm.