Ureteral stents

Abstract

To provide a ureteral stent capable of providing a path for discharging urine from the kidney to the bladder by arranging the ureteral stent in the body of a patient while minimizing discomfort of the patient.SOLUTION: Provided is a ureteral stent. The stent includes a first portion including a first wall defining a first lumen. The stent can further include a second portion including a second wall defining a second lumen. The second portion may be enabled to substantially close when an external pressure is applied to the stent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] TECHNICAL FIELD The present disclosure relates to medical devices, and more particularly to ureteral stents. [Background technology]

[0002] Ureteral stents may be placed in a patient's body to aid in the drainage of urine from the kidney to the bladder. For example, after certain urinary stone procedures, small or fragmented stones or tumors may become lodged in the ureter, which may impede or block the flow of urine from the kidney to the bladder. Ureteral stents function to expand the ureter, allowing urine to pass through stones or stone fragments and flow from the kidney to the bladder.

[0003] Ureteral stents generally comprise a tubular member terminating in two opposing ends that allow urine to flow, however, current stents can cause significant discomfort to the patient during urination. Summary of the Invention [Problem to be solved by the invention]

[0004] It would therefore be desirable to improve on the current technology by providing a ureteral stent that can be placed within a patient's body and provide a pathway for the drainage of urine from the kidney to the bladder while minimizing patient discomfort. [Means for solving the problem]

[0005] The present disclosure provides a ureteral stent that significantly minimizes discomfort to the patient during urination. A possible cause of discomfort may occur while draining urine from the stent. When the bladder muscle pushes urine out, it may flush some of the urine back from the stent to the kidney. Reflux of urine back into the kidney may be a possible cause of flank pain.

[0006] Certain embodiments provide a stent that can include a first portion having a first wall defining a first lumen and a second portion having a second wall defining a second lumen, wherein the second portion can be enabled to substantially close when an external pressure is applied to the stent.

[0007] The objects, features, and advantages of the embodiments disclosed herein can be better understood by referring to the following description in conjunction with the accompanying drawings. The drawings are not intended to limit the scope of the claims contained herein. For purposes of clarity, not every element may be shown in every drawing. The drawings are not necessarily to scale, with emphasis instead being placed on illustrating the embodiments, principles, and concepts. Thus, the features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments of the invention, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0008] [Figure 1] 1 illustrates a ureteral stent according to certain embodiments of the present invention deployed in a patient's kidney, ureter, and bladder. [Figure 2A] 1A-1D are cross-sectional views of a portion of a stent, according to certain embodiments. [Figure 2B] 1A-1D are cross-sectional views of a portion of a stent, according to certain embodiments. [Figure 3A] 1A-1D are cross-sectional views of a portion of a stent, according to certain embodiments. [Figure 3B] 1A-1D are cross-sectional views of a portion of a stent, according to certain embodiments. [Figure 4] 1A-1D are cross-sectional views of a portion of a stent, according to certain embodiments. [Diagram 5] 1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. [Figure 6]1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. [Figure 7] 1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. [Figure 8] 1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. [Figure 9] 1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. [Figure 10] 1 is a graph plotting pressure on a stent (Pcr) versus thickness of portions of a stent (t) for various example embodiment combinations of stent French size and material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] These teachings are directed to stents. The stent may be a medical stent. The stent may be any stent, such as a ureteral stent. The ureteral stent may function to aid in the drainage of fluid or urine from the kidney to the bladder in a patient. For example, after certain urinary stone or tumor medical procedures, small pieces or fragments of the stone or tumor may get into the ureter, which may impede or block the flow of urine from the kidney to the bladder. The ureteral stent may function to dilate the ureter, which allows the stone or stone fragments to pass through and allow the fluid or urine to flow from the kidney to the bladder.

[0010] 1 illustrates a stent 100 in accordance with an exemplary embodiment of the present invention. The stent 100 is illustrated inside a patient's urinary tract 10. One end of the stent 100 is placed inside the patient's kidney 12 and the opposite end is placed within the patient's bladder 14.

[0011] 2A illustrates portions of a stent 100, according to certain embodiments. The stent 100 can include a first portion 102 and a second portion 104. The first portion 102 can include a first wall 106 that defines a first lumen 108. The second portion 104 can include a second wall 110 that defines a second lumen 112. The first and second portions can be placed in the urinary tract 10 of a patient. The second portion 104 can be placed in the bladder 14. In some embodiments, the second portion 104 can be placed in the ureteral portion 16. The first and second portions can be generally hollow members including an opening or lumen extending from one retention end to the other end.

[0012] The first lumen 108 and the second lumen 112 can function to allow a wire to pass through the tubular member to aid in the insertion and removal of the stent from the patient. The first lumen 108 and the second lumen 112 can have a suitable size or diameter to allow for the insertion and removal of a wire. The diameter of the first lumen 108 and the second lumen 112 can be on the order of about 0.040 inches to about 0.045 inches. However, larger and smaller sizes can be used depending on the particular use of the stent. Once inserted into the patient, the first lumen 108 and the second lumen 112 can also function to allow urine or other fluids to flow from the kidney 12 to the bladder 14.

[0013] The first wall 106 and the second wall 110 can have any suitable thickness. The thickness of the first wall 106 can be generally constant. In some embodiments, the thickness of the first wall 106 can vary from stent to stent. The thickness of the second wall 110 can vary or change along its length between the major and minor cross sections or along various shapes. In some embodiments, the thickness of the second wall 110 is less than the thickness of the first wall 106.

[0014] In some embodiments, the thickness of the first wall 106 or second wall 110 can be on the order of about 0.1 mm to about 1.8 mm. In some configurations, it may be preferred that the diameter of the first wall and / or second wall is less than 2.3 mm. The size of the second portion 104 and / or first portion 102 can have a French size (F) on the order of about 1 F to about 16 F. However, larger or smaller French sizes may be used depending on the particular use for the stent.

[0015] The length of the stent 100 may be on the order of about 50 mm to about 350 mm, although longer or shorter lengths are contemplated depending on the particular application of the stent.

[0016] FIG. 2B illustrates a stent 200, such as the stent 100 of FIG. 2A, when an external pressure is applied to the stent 200, according to certain embodiments. The external pressure can be the peristaltic pressure of a ureteral contracture, the fluid pressure around the stent in the ureter, or the fluid pressure in the bladder. As illustrated in FIG. 2B, the second portion 204 is substantially closed due to the external pressure while the first portion 102 is open and fluid is passing through. In one embodiment, the second portion 104 of the stent 100 is enabled to be substantially closed when an external pressure is applied to the stent 100. The second portion 104 of the stent 100 can be closed under the external pressure. The closure can occur due to differences in material properties, such as various geometries, material non-homogeneity, dimensions, etc. By closing the second portion 104 of the stent 100, fluid, such as urine, cannot return from the stent 100 toward the kidney 12. The reflux of urine and / or fluids into the kidney can cause significant discomfort to the patient. Therefore, the second portion 104 can act as a one-way valve.

[0017] In some embodiments, the second wall 110 of the second portion 104 / 204 can be made from a material having a lower durometer than the first wall 106 of the first portion 102, thus helping to allow the second portion 104 to close under pressure. In some embodiments, the second portion 104 / 204 can have a second wall 110 / 210 that has a thinner thickness than the first wall 106.

[0018] The first lumen 108 and the second lumen 112 can have any cross-sectional size or shape. For example, the first lumen and / or the second lumen can be cylindrical, round, spherical, rectangular, square, or combinations thereof in cross-section.

[0019] Figures 3A and 3B illustrate cross-sectional views of a portion of a stent, such as the stent 100 illustrated in Figure 2A, according to certain embodiments. Figure 3A illustrates a stent 100 having a cylindrical cross-section. Figure 3B illustrates a stent 100 having an oval or semi-oval cross-section. As shown in Figure 3B, the stent 100 can have a circular outer surface, i.e., a cylindrical shape, and a lumen 112 that is oval shaped.

[0020] The first portion 102 and the second portion 104 can have any suitable cross-section. For example, the cross-section of the first portion 102 and the second portion 104 can be generally circular or cylindrical, hexagonal, elliptical, oval, or any geometric shape. The cross-section can be generally constant between the two opposing ends (i.e., generally circular along the entire length of the stent 100). Or, the cross-section of the first portion 102 and the second portion 104 can be generally non-constant along its entire length (i.e., one portion of the stent can have a generally circular cross-section and the next other portion can have an oval or flat cross-section).

[0021] In some embodiments, the stent 100 is adapted to minimize tissue irritation by reducing the contact area between the stent 100 and tissue, such as the ureter 16 or bladder 14. In some embodiments, the stent 100 is adapted to minimize tissue irritation by using materials with different durometers in the stent 100 to increase flexibility.

[0022] 4 illustrates a stent 300 having a first portion 302 and a second portion 304. The second portion 304 can have multiple portions having individual walls 310 that define lumens 312 that can substantially close when the stent 300 is subjected to external pressure.

[0023] In some embodiments, the stent can be made of one or more materials. The one or more materials of the stent can be resistant to tissue adhesion and coating. The one or more materials can be soft or flexible so that the stent and / or the retention ends can conform to the lumen or passage of the patient into which the stent is inserted. The one or more materials can be sufficiently rigid so that the stent and / or the retention ends support or maintain the body passage at a particular diameter.

[0024] According to certain embodiments, one or more materials of the stent, the first portion and the second portion may include chitosan, silicone, polyurethane, polyethylene blends, polytetrafluoroethylene (PTFE), thermoplastic polyurethane (TPU), polyolefin elastomer (POE), ethylene-vinyl acetate (EVA), polystyrene-butadiene-styrene (SBS), silicone rubber, nylon, polyethylene or polythene (PE), polypropylene (PP), thermoplastic C-Flex®, Percuflex®, Tecoflex™; Pebax®, stainless steel, metal, metal alloy, Nitinol material, nickel, titanium alloy superalloy, chrome cobalt, or combinations thereof. The material may include a shape memory material. The first portion and / or the second portion may include two or more materials (i.e., dual durometer or multi-durometer) that transition from a hard material at the tubular member to a soft or flexible material at the retention end. The material may be a swellable polymer that is adapted to expand when in contact with fluid or when temperature is increased (eg, when the stent is placed within a patient's body).

[0025] The stent may be inserted or implanted in the patient according to a method. The method may include inserting a guidewire into the patient and advancing the guidewire to the bladder and then to the kidney. The method then includes loading or delivering the stent over the guidewire. The method includes pushing or delivering the stent along the guidewire in the patient. The stent may then remain in the patient to expand the ureter, thereby allowing urine to pass the stone or stone fragments and flow from the kidney to the bladder. The stent may be permanently retained in the patient. The stent may be made of a biodegradable material, in which case the stent will dissolve or degrade in the patient over time. The stent may be removed from the patient by inserting another guidewire into the patient and through the stent.

[0026] Figures 5-10 are graphs plotting pressure on a stent (Pcr) versus thickness of a stent portion for various exemplary embodiment combinations of stent (t) French size and material. Figures 5-10 illustrate computer modeling data for a stent having a second portion of three different lengths made from materials with different elastic moduli and closing at different wall thicknesses. That is, the second portion of the stent can close when the stent is subjected to an external pressure of about 40-60 cm H2O.

[0027] The Flugges equation for the linear theory of orthotropic cylindrical shells (Equation 1 below) was applied to calculate the instability of the stent 100 in the presence of an external pressure, which can be a fluid passing through or around the stent 100, patient movement, etc.

[0028] EQ.1: Pcr = [2πEt 2 (t / R) 1 / 2 / [3(6) 1 / 2 (1-μ 2 ) 3 / 4 RL]] * 10197.2

[0029] In Equation 1 above, R=radius of stent 100 (mm); L=length of stent 100 (mm); t=thickness of stent 100 (mm); Pcr=critical pressure (cmH2O, 1MPa=10197.2cmH2O); E=elastic modulus (MPa); and μ=Poisson's ratio (μ=0.5 was selected).

[0030] The pressure within the renal artery or the fluid pathway through the kidney during initial perfusion is approximately 40-60 cmH2O.

[0031] With specific reference to FIG. 5, three different stents of 5 Fr. size made from EVA material having an elastic modulus of 11 MPa were tested.

[0032] As illustrated in Figure 5, a first stent having a second portion with a length of 300 mm does not fall within the external pressure range of 40 cm H2O to 60 cm H2O. A second stent having a second portion with a length of 150 mm falls within the pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.23 mm to 0.27 mm. A third stent having a second portion with a length of 75 mm falls within the pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.17 mm to 0.2 mm.

[0033] With specific reference to FIG. 6, three different stents of 5 Fr. size made from a TPU material having an elastic modulus of 12 MPa were tested.

[0034] As illustrated in Figure 6, a first stent having a second portion with a length of 300 mm does not fall within the external pressure range of 40 cm H2O to 60 cm H2O. A second stent having a second portion with a length of 150 mm falls within the pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.22 mm to 0.26 mm. A third stent having a second portion with a length of 75 mm falls within the pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.17 mm to 0.2 mm.

[0035] With specific reference to FIG. 7, three different stents of 8 Fr. size made from EVA material having an elastic modulus of 11 MPa were tested.

[0036] As illustrated in Figure 7, a first stent having a second portion with a length of 300 mm falls within an external pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.47 mm to 0.51 mm. A second stent having a second portion with a length of 150 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.34 mm to 0.38 mm. A third stent having a second portion with a length of 75 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.25 mm to 0.3 mm.

[0037] With specific reference to FIG. 8, three different stents of 8 Fr. size made from EVA material having an elastic modulus of 70 MPa were tested.

[0038] As illustrated in Figure 8, a first stent having a second portion with a length of 300 mm falls within an external pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.23 mm to 0.25 mm. A second stent having a second portion with a length of 150 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.15 mm to 0.17 mm. A third stent having a second portion with a length of 75 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.12 mm to 0.15 mm.

[0039] With specific reference to FIG. 9, three different stents of 8 Fr. size made from a TPU material having an elastic modulus of 12 MPa were tested.

[0040] As illustrated in Figure 9, a first stent having a second portion with a length of 300 mm falls within an external pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.4 mm to 0.5 mm. A second stent having a second portion with a length of 150 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.33 mm to 0.36 mm. A third stent having a second portion with a length of 75 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.25 mm to 0.3 mm.

[0041] With specific reference to FIG. 10, three different stents of 8 Fr. size made from Pebax® material having an elastic modulus of 81 MPa were tested.

[0042] As illustrated in Figure 10, a first stent having a second portion with a length of 300 mm falls within an external pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.18 mm to 0.25 mm. A second stent having a second portion with a length of 150 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.14 mm to 0.17 mm. A third stent having a second portion with a length of 75 mm falls within a pressure range of 40 cm H2O to 60 cm H2O with a wall thickness of about 0.13 mm to 0.15 mm.

[0043] The description and illustrations provided herein are intended to acquaint those skilled in the art with the invention, its principles, and its practical application. It is understood that the above description is illustrative and not limiting. Those skilled in the art may adapt and apply the present teachings in their numerous forms, as may best suit the requirements of a particular use.

[0044] Thus, the specific embodiments of the present teachings described are not intended as being exhaustive or limiting of the present teachings. Accordingly, the scope of the present teachings should be determined not with reference to the above description, but instead with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The omission in the following claims of any aspect of the subject matter disclosed herein shall not be construed as a disclaimer of such subject matter, nor as an indication that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

[0045] Multiple elements or steps may be provided by a single integrated element or step, or a single element or step may be divided into multiple separate elements or steps.

[0046] The disclosure of "a" or "one" describing an element or step is not intended to exclude additional elements or steps.

[0047] By using the term "may" herein, any described attribute that "may" be included is intended to be optional.

[0048] Terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or areas, but these elements, components, regions, layers, and / or areas should not be limited by these terms. These terms may be used to distinguish one element, component, region, layer, or area from another region, layer, or section. Terms such as "first," "second," and other numerical terms, when used herein, do not imply an arrangement or order unless expressly indicated in the text. Thus, a first element, component, region, layer, or section described below may be referred to as a second element, component, region, layer, or section, unless it deviates from the teachings.

[0049] Spatially relative terms, such as "inside," "outside," "beneath," "below," "lower," "above," "top," and the like, may be used for ease of description when describing the relationship of one element or feature to another element or feature as shown in the figures. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were upside down, the elements described as "below," "beneath" the other element or feature would be positioned "above" the other element or feature. Thus, the term "below" in this example may encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein would be interpreted accordingly.

[0050] The disclosures of all articles and references, including patent applications and patent application publications, are incorporated by reference for all purposes. Other combinations are possible, as may be found in the following claims, and are also incorporated by reference herein. [Explanation of symbols]

[0051] 10 Urinary tract 12 Kidneys 14 Bladder 16 Ureter 100 stents 102 First Part 104 Second Part 106 The First Wall 108 First Lumen 110 The Second Wall 112 Luminal part 112 Second Lumen 200 stents 204 Second Part 300 stents 302 First Part 304 Second Part 310 Wall 312 Luminal part

Claims

1. 1. A stent comprising: at least two first sections, each of the at least two first sections having a first wall; the first wall defines a first lumen; Each of the at least two first portions has a first maximum width. at least two first portions; a second portion longitudinally interposed between the at least two first portions, the second portion has a second wall defining a second lumen; the second portion has a second maximum width that is less than the first maximum width; Stent 40cm H 2 O (cm H 2 O) to 60 cm H 2 When subjected to an external pressure of O, the second lumen is configured to transition from an initial open configuration to a closed configuration along the lumen portion to minimize backflow of liquid. and a second portion. Stent.

2. The first lumen remains substantially open when the external pressure is applied to the stent.

2. The stent of claim 1.

3. Closing the second lumen prevents liquid from entering the first lumen.

2. The stent of claim 1.

4. The stent is a ureteral stent, and the second lumen is sized and shaped to be placed in a patient's bladder.

2. The stent of claim 1.

5. The stent is a ureteral stent, and the second lumen is sized and shaped to be placed within the ureter of a patient.

2. The stent of claim 1.

6. The diameter of the first lumen and the second lumen is between 1 mm and 1.14 mm.

2. The stent of claim 1.

7. The thickness of the first wall and the second wall is between 0.1 mm and 1.8 mm.

2. The stent of claim 1.

8. 1. A stent comprising: a plurality of first portions, each of the plurality of first portions having a first wall with a first wall thickness; The first wall defines a first lumen. A plurality of first portions; a second portion between two longitudinally separated first portions of the plurality of first portions, the second portion having a second wall; and Equipped with the second wall has a second wall thickness less than the first wall thickness; the second wall defines a second lumen; 40cm H on the stent 2 O (cm H 2 O) to 60 cm H 2 In response to an external pressure of O, the second lumen is configured to transition from an initial open configuration to a closed configuration, wherein in the closed configuration, liquid is prevented from flowing back into at least one of the plurality of first portions. Stent.

9. The second wall is constructed of a material having a lower hardness than the first wall.

9. The stent of claim 8.

10. the stent is a ureteral stent sized and configured for introduction through the ureter of a subject; One end of the stent is configured to be placed within a kidney and an opposite end of the stent is configured to be placed within a bladder.

9. The stent of claim 8.

11. 1. A stent comprising: at least two first sections, each of the at least two first sections having a first maximum width and a first wall with a first wall thickness; The first wall defines a first lumen. At least two first sections; a second section longitudinally interposed between the at least two first sections, the second section comprising: a plurality of subsections, each subsection having a second wall; At least a portion of each subsection has a second maximum width that is less than the first maximum width; each subsection of the plurality of subsections has a length less than the at least two first sections; The second section is placed in at least one of the bladder or ureteral segments and has a length of 40 cm. 2 O (cm H 2 O) to 60 cm H 2 At least one of the plurality of subsections is configured to individually close upon application of an external pressure of O. The second section and A stent comprising:

12. At least one of the plurality of subsections has a generally circular, generally hexagonal, or generally elliptical cross-section.

12. The stent of claim 11.

13. Each of the plurality of subsections has a similar cross-section.

12. The stent of claim 11.

14. A cross-section of the at least two first sections is different from a cross-section of the second section.

12. The stent of claim 11.

15. The second wall is constructed of a material having a lower hardness than the first wall.

12. The stent of claim 11.

16. At least one of the at least two first sections and the second section is constructed from a shape memory material.

12. The stent of claim 11.

17. The at least two first sections are constructed from a different material than the second sections.

12. The stent of claim 11.

18. The stent is a ureteral stent sized and configured to be introduced through the ureter of a subject.

12. The stent of claim 11.

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