Stent delivery device, method for manufacturing a stent delivery device, and stent

Abstract

The present invention provides a stent delivery device that facilitates the smooth operation of exposing the stent from the outer sheath. [Solution] The stent delivery device comprises an inner sheath, a stent 2 attached to the outer circumference of the inner sheath, an outer sheath attached to cover the outer circumference of the inner sheath and the stent 2, and a pressing member (pusher) that restricts the proximal movement of the stent 2. The outer sheath is attached so as to be slidable relative to the inner sheath, and is configured to allow the stent 2 to be exposed to the outside. The stent 2 is a covered stent in which a wire 21 and a resin cover 20 are integrated. A solid lubricant 7, which is stearate powder, is attached to the outer circumference of the stent 2.

Description

Technical Field

[0001] The present invention relates to a stent delivery device capable of implanting a stent into a body tube.

Background Art

[0002] As an implant for medical use in the body, there is a stent. The stent is used by being implanted in a stenosis, occlusion, adhesion, etc. that has occurred in a body lumen.

[0003] For example, Patent Document 1 discloses a stent delivery device including an inner sheath to which a cylindrical stent is attached to an outer peripheral surface, and an outer sheath that is axially relatively movable with respect to the inner sheath and can accommodate the stent between the inner sheath and the outer sheath. Patent Document 1 describes that in order to appropriately release the stent while fixing the stent at a predetermined position of the inner sheath and relatively moving the outer sheath with respect to the inner sheath, a groove portion is provided on the outer periphery of the inner sheath.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the stent delivery device described in Patent Document 1, when the outer sheath is relatively moved with respect to the inner sheath, a frictional force is applied from the stent to the outer sheath. <For example, this frictional force becomes particularly large when deploying the outer sheath while the inner sheath and stent are bent. As a result, this frictional force can hinder the movement of the outer sheath or cause the stent to move together with the outer sheath, indicating room for improvement in the smooth exposure of the stent.

[0006] This invention has been made in view of the above-mentioned problems, and provides a stent delivery device that can facilitate the operation of exposing the stent from the outer sheath. [Means for solving the problem]

[0007] The stent delivery device of the present invention comprises an inner sheath, a stent attached to the outer circumference of the inner sheath, an outer sheath attached to cover the outer circumference of the inner sheath and the stent, and a retaining member that restricts the proximal movement of the stent, wherein the outer sheath is slidably attached relative to the inner sheath and configured to expose the stent to the outside, the stent is a covered stent in which a wire and a resin cover are integrated, and a solid lubricant, which is stearate powder, is attached to the outer circumference of the stent. [Effects of the Invention]

[0008] The stent delivery device of the present invention makes it possible to smoothly slide the outer sheath against the inner sheath to expose the stent from the outer sheath. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram schematically shows a stent delivery device according to an embodiment of the present invention, and illustrates the state of the stent during deployment. [Figure 2] This is a schematic diagram of a stent. [Figure 3] This is a schematic diagram showing a cross-section of the end of the stent in part III of Figure 2. [Figure 4] This is a schematic diagram showing an enlarged view of section IV in Figure 2. [Figure 5] This figure shows the difference in the deployment load required when deploying a comparative example stent without lubricant and an example stent with lubricant from the outer sheath. [Figure 6] This is a schematic diagram showing a cross-section of the end portion of the stent (corresponding to the part shown in Figure 3) according to the first modified example. [Figure 7] This is a schematic diagram showing a cross-section of the end portion of the stent (corresponding to the part shown in Figure 3) according to the second modified example. [Modes for carrying out the invention]

[0010] Hereinafter, a stent delivery device 1 according to an embodiment of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely examples to facilitate understanding of the present invention and do not limit it. That is, the shape, dimensions, arrangement, etc., of the components described below can be changed or improved without departing from the spirit of the present invention, and of course, equivalents thereof are included in the present invention. Furthermore, the drawings do not necessarily accurately represent the dimensional ratios of the components that make up the stent delivery device 1, such as length, width, and height. The proximal side (basal end) refers to the side that is positioned closer to the surgeon during the procedure, while the distal side (tip end) refers to the side that is positioned further away from the surgeon during the procedure. Furthermore, in all drawings, similar components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0011] <<Overview>> First, an overview of the stent delivery device 1 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the stent delivery device 1 according to an embodiment of the present invention, and shows the state in which the stent 2 is in the process of being deployed, and Figure 2 is a schematic diagram showing the stent 2.

[0012] As shown in FIG. 1, the stent delivery device 1 includes an inner sheath 33, a stent 2 attached to the outer periphery of the inner sheath 33, an outer sheath 31 attached to cover the outer peripheries of the inner sheath 33 and the stent 2, and a pressing member (pusher 6) that restricts the proximal movement of the stent 2. The outer sheath 31 is attached so as to be slidable relative to the inner sheath 33, and is configured to expose the stent 2 to the outside. As shown in FIG. 2, the stent 2 is a covered stent in which a wire 21 and a resin cover 20 are integrated. A solid lubricant 7, which is a powder of stearate, adheres to the outer peripheral portion of the stent 2.

[0013] The pusher 6 is disposed between the inner sheath 33 and the outer sheath 31, is located at a position radially overlapping the stent 2, and is disposed proximal to the stent 2, thereby restricting the proximal movement of the stent 2. Specifically, the stent 2 is configured to be exposed from the distal end of the outer sheath 31 when the outer sheath 31 moves proximally with respect to the stent 2.

[0014] According to the above configuration, due to the adhesion of the stearate powder, when the outer sheath 31 is slid relative to the inner sheath 33, the frictional resistance (deployment load) applied from the stent 2 can be kept low.

[0015] <Overall Configuration> The stent delivery device 1 supplies the stent 2 into a body tube (for example, inside a digestive organ). As shown in FIG. 1, the stent delivery device 1 includes a sheath 3, a stent 2 accommodated in the sheath 3, and a pusher 6 that restricts the proximal movement of the stent 2. The sheath 3 is composed of an inner sheath 33 and an outer sheath 31 attached to the outer periphery of the inner sheath 33, and the stent 2 is accommodated between the inner sheath 33 and the outer sheath 31. The inner sheath 33 is formed in a tubular shape so that the guide wire 34 can pass through it, and a tip chip 5 is attached to the tip of the inner sheath 33. The outer sheath 31 is attached to the inner sheath 33 so as to be slidable in the longitudinal direction. When it is pulled proximally by an operating portion (not shown), the stent 2 can be exposed.

[0016] <Stent> Next, the stent 2 according to the present embodiment will be described with reference to FIGS. 2 to 5 in addition to FIG. 1. FIG. 2 is a schematic view showing the stent 2, FIG. 3 is a schematic cross-sectional view of an end portion 2a of the stent 2 according to part III of FIG. 2, and FIG. 4 is a schematic view showing an enlarged view of part IV of FIG. 2. FIG. 5 is a diagram showing the difference in the deployment load required when deploying the stent 2 of the comparative example without the solid lubricant 7 and the stent 2 of the example with the solid lubricant 7 from the outer sheath 31.

[0017] As described above, the stent 2 according to the present embodiment is a straight type covered stent in which the wire 21 and the resin cover 20 are integrally formed. Since the stent 2 is a covered stent, when the outer sheath 31 is moved proximally with respect to the stent 2 in order to expose the stent 2 from the outer sheath 31, a load due to friction is particularly applied from the stent 2 to the outer sheath 31. In view of this point, as will be described later with reference to FIG. 3, a solid lubricant 7 is applied to the stent 2. More specifically, after the solid lubricant 7 is applied to the surface of the stent 2, an external force is applied so that the solid lubricant 7 is in a state of being press-fitted against the surface of the stent 2.

[0018] In the resin cover 20 of the stent 2 according to the present embodiment, the inner layer 20a is formed of a silicone resin, and the outer layer 20b is formed of a PTFE resin (specifically, an extruded polytetrafluoroethylene resin). These layers are joined with an adhesive, for example, and then crimped. The wire 21 according to the present embodiment is woven in a mesh shape and is enclosed in the inner layer 20a of the resin cover 20.

[0019] The solid lubricant 7 according to this embodiment is a powder mainly composed of stearate. Various types of stearate can be used, but alkali metal salts or alkaline earth metal salts of stearic acid are preferred. More specifically, calcium stearate or potassium stearate can be preferably used. Among the stearates, calcium stearate is particularly preferred because it has high biocompatibility, low water solubility, and good lubricity.

[0020] The particle size of the solid lubricant 7 is not particularly limited, but the solid lubricant 7 used is one that passes through a mesh conforming to mesh number 325 as specified in ASTM E-11-61, for example. For example, if the maximum outer diameter of the solid lubricant 7 is 0.044 mm or less, it has excellent adhesion to the resin cover 20, and spillage of the solid lubricant 7 from the resin cover 20 can be effectively suppressed during the procedure of moving the inner sheath 33 relative to the stent 2. The preferred lower limit of the particle size of the solid lubricant 7 is not particularly limited, but it is preferable that the particle size is 0.01 mm or more. By using such a particle size, excessive aggregation of the solid lubricant 7 can be suppressed and the solid lubricant 7 can be well dispersed on the surface of the resin cover 20. Different types of stearates may be mixed and used as the solid lubricant 7, and other fatty acid salts may be included as lubricating aids as components other than stearate.

[0021] Within the region demarcated by the mesh 21a of the wires 21 constituting the stent 2, the solid lubricant 7 adheres to the peripheral portion 21c of the mesh 21a at a higher density than to the central portion 21b of the region demarcated by the wires 21.

[0022] In the stent 2 according to this embodiment, as shown in Figure 3, the wire 21 is embedded in the inner layer 20a. In this case, the "peripheral portion 21c of the mesh 21a" refers to the outer surface of the part that contains the wire 21 constituting the mesh 21a, and includes the peripheral region of the protrusion 20e that rises around the wire 21 in the outer layer 20b (the vicinity of the protrusion 20e in the recess 20f). The "peripheral region of the protrusion 20e" is, for example, the region within the grid-like area demarcated by the protrusion 20e, where the height is 20 percent on the side closer to the top of the protrusion 20e, relative to the height from the bottom of the recess 20f to the top of the protrusion 20e.

[0023] For example, if the wire 21 is exposed on the outer surface of the stent 2, the "peripheral portion 21c of the mesh 21a" will not be based on a part of the resin cover 20, but will be the direct peripheral region of the wire 21. With the above configuration, the solid lubricant 7 adheres at a high density to the peripheral portion 21c of the mesh 21a (the peripheral region of the protrusion 20e), where the contact pressure with the outer sheath 31 tends to increase. This suppresses the application of frictional force to the inner surface of the outer sheath 31 by the protrusion 20e and its peripheral portion.

[0024] As shown in Figure 3, the outer circumferential surface 2c of the stent 2 has a convex portion 20e that protrudes radially outward and a concave portion 20f that is recessed radially inward. The solid lubricant 7 is thicker on the concave portion 20f than on the convex portion 20e.

[0025] Furthermore, "on the convex portion 20e" refers to the maximum protruding part (top) of the convex portion 20e, and the rest is referred to as the concave portion 20f, and "on the concave portion 20f" refers to the maximum recessed part (bottom) of the concave portion 20f. For example, the average thickness of the solid lubricant 7 on the recess 20f is 3 to 10 times thicker than the average thickness of the solid lubricant 7 on the protrusion 20e. According to the above configuration, the uneven portion 20d (protrusions 20e and recesses 20f) can be leveled (the difference in height can be reduced) by the solid lubricant 7, thereby reducing the frictional resistance applied from the stent 2 to the outer sheath 31.

[0026] As shown in Figure 3, the solid lubricant 7 is also adhering to the inner circumferential surface 2b of the end portion 2a of the stent 2. "End 2a of stent 2" means at least one of the ends in the longitudinal direction of a long, cylindrical stent 2. With the above configuration, the solid lubricant 7 is attached to the inner circumferential surface 2b of the end 2a of the stent 2, which prevents the inner circumferential surfaces 2b of the end 2a of the stent 2 from sticking together when the stent 2 is deployed, making it easier for the end 2a of the stent 2 to open.

[0027] As shown in Figures 3 and 4, the solid lubricant 7 adheres to the outer circumferential surface 2c of the stent 2, the inner circumferential surface 2b of the end portion 2a of the stent 2, and the inner circumferential surface 2b of the central portion 2d of the stent 2, in that order of increasing density. For example, the end portion 2a of stent 2 is the 5 percent region on the end side of the total length of stent 2 in the axial direction, and the central portion 2d of stent 2 is the remaining region.

[0028] With the above configuration, the solid lubricant 7 adheres to the outer circumferential surface 2c of the stent 2 at a higher density than the inner circumferential surface 2b of the end portion 2a of the stent 2, thereby reducing the frictional resistance when sliding the outer sheath 31.

[0029] Furthermore, because the solid lubricant 7 is attached to the inner circumferential surface 2b of the end portion 2a of the stent 2 at a higher density than the inner circumferential surface 2b of the central portion 2d, it is possible to make it easier to open the end portion 2a when deploying the stent 2, while also preventing the stent 2 from unexpectedly detaching from the inner sheath 33. In other words, when deploying the stent 2, the solid lubricant 7 prevents the inner circumferential surfaces 2b at the end 2a from sticking together. Furthermore, the density of the solid lubricant 7 adhering to the central part 2d of the inner circumferential surface 2b is lower than the density of the solid lubricant 7 adhering to the end 2a, thereby preventing the stent 2 from unexpectedly detaching from the inner sheath 33.

[0030] The solid lubricant 7 in this embodiment is formed of calcium stearate as described above. The solid lubricant 7 is applied to the outer surface 2c of the stent 2 in a 1 cm layer. 2 They are attached at a density of 0.5 mg to 2.5 mg per unit. According to the above configuration, the frictional force applied from the stent 2 to the outer sheath 31 can be effectively reduced.

[0031] It is preferable that the portion of the resin cover 20 of the stent 2 to which the solid lubricant 7 is attached (outer layer 20b) is formed of at least PTFE resin. In this embodiment, the resin cover 20 of the stent 2 is formed of a silicone resin inner layer 20a and a PTFE resin outer layer 20b, as described above, but the configuration is not limited to this. For example, as will be described later, the resin cover 20 may be formed of PTFE resin only. According to the above configuration, the lubricity can be effectively enhanced by attaching the solid lubricant 7 to the PTFE resin.

[0032] Furthermore, as will be described later, the resin cover 20 may be made solely of silicone resin, or it may be made of different materials in the longitudinal direction (for example, made of PTFE resin in the center and silicone resin at both ends).

[0033] As shown in Figure 5, there was a significant difference in deployment load (the load required to pull the outer sheath 31 to expose the stent 2) between the stents 2 of Examples 1 to 3, which were coated with the solid lubricant 7 of the stent delivery device 1 according to this embodiment, and the stents (not shown) of Comparative Examples 1 to 3, which were not coated with the solid lubricant 7. Examples 1 to 3 and Comparative Examples 1 to 3 used the same stent delivery device 1, and the deployment load was measured three times each, differing in whether or not the solid lubricant 7 was applied. Specifically, the deployment load was 43.6 N in Comparative Example 1, 20.9 N in Example 1, 42.4 N in Comparative Example 2, 17.1 N in Example 2, 40.1 N in Comparative Example 3, and 26.1 N in Example 3. Therefore, it was found that applying the solid lubricant 7 to the stent 2 significantly reduced the deployment load to approximately half.

[0034] (First variation) Next, a first modified example of the stent 2 (resin cover 20) according to this embodiment will be described, mainly with reference to Figure 6. Figure 6 is a schematic diagram showing a cross-section of the end portion (corresponding to Figure 3) of the stent 2 according to the first modified example. As described above, various configurations can be adopted for the resin cover 20. For example, in the resin cover 30 according to the first modified example, as shown in Figure 6, it is composed only of an outer layer 20b bonded to the outer circumference of the wire 21. In this case, if the outer layer 20b is a flexible film, such as PTFE resin, the outer layer 20b will be formed to follow the wire 21. Therefore, on the outer surface of the resin cover 20, the portion that overlaps with the wire 21 becomes a protrusion 20e (see Figure 3).

[0035] Furthermore, as described with reference to Figures 1, 3, and 4 in the above embodiment, the solid lubricant 7 adheres at a high density to the peripheral portion 21c of the mesh 21a (the peripheral region of the protrusion 20e), where the contact pressure with the outer sheath 31 tends to increase, thereby suppressing the frictional force applied by the protrusion 20e to the inner surface of the outer sheath 31.

[0036] (Second variation) Next, a second modified example of the stent 2 (resin cover 20) according to this embodiment will be described, mainly with reference to Figure 7. Figure 7 is a schematic diagram showing a cross-section of the end portion (corresponding to Figure 3) of the stent 2 according to the second modified example. In the second modified resin cover 40, as shown in Figure 7, the wire 21 is enclosed within the resin cover 40. In other words, the resin cover 40 is provided on both the inner and outer circumferences of the wire 21. The resin cover 40 in this example is made of silicone resin, but it may of course be made of PTFE resin or any of the other resins mentioned above.

[0037] In this case as well, the portion of the outer surface of the resin cover 40 that overlaps with the wire 21 becomes a protrusion 20e (see Figure 3). Furthermore, as explained with reference to Figures 1, 3, and 4 in the above embodiment, the solid lubricant 7 adheres at a high density to the peripheral portion 21c of the mesh 21a (the peripheral region of the protrusion 20e), where the contact pressure with the outer sheath 31 tends to increase, thereby suppressing the application of frictional force by the protrusion 20e to the inner surface of the outer sheath 31.

[0038] The above embodiment encompasses the following technical concepts. (1) Inner sheath and, A stent attached to the outer circumference of the inner sheath, An outer sheath is attached so as to cover the outer circumference of the inner sheath and the stent, The system includes a retaining member that restricts the proximal movement of the stent, The outer sheath is mounted so as to be slidable relative to the inner sheath, and is configured to allow the stent to be exposed to the outside. The stent delivery device is characterized in that the stent is a covered stent in which a wire and a resin cover are integrated, and a solid lubricant, which is stearate powder, is attached to the outer circumference of the stent. (2) Within the region demarcated by the wire mesh constituting the stent, The stent delivery device according to (1), wherein the solid lubricant is deposited at a higher density on the peripheral portion of the mesh than on the central portion of the region separated by the wire. (3) The outer surface of the stent has a convex portion that protrudes radially outward and a concave portion that is recessed radially inward. The stent delivery device according to (1) or (2), wherein the solid lubricant is applied more thickly on the recessed portion than on the convex portion. (4) The stent delivery device according to any one of (1) to (3), wherein the solid lubricant is also attached to the inner circumferential surface of the end of the stent. (5) The stent delivery device according to (4), wherein the solid lubricant is adhered in increasing density to the outer circumferential surface of the stent, the inner circumferential surface of the end of the stent, and the inner circumferential surface of the central part of the stent, in that order. (6) The solid lubricant is formed of calcium stearate, On the outer surface of the stent, 1 cm 2 A stent delivery device according to any one of items (1) to (5), having a density of 0.5 mg or more and 2.5 mg or less per unit. (7) The stent delivery device according to any one of (1) to (6), wherein the portion of the resin cover of the stent to which the solid lubricant is attached is formed of at least PTFE resin. [Explanation of Symbols]

[0039] 1. Stent delivery device 2 stents 2a end 2b Inner surface 2c Outer surface 2d central part 3 Sheath 5 Tip 6. Pusher (pressure member) 7. Solid lubricants 20 resin cover 20a Inner layer 20b outer layer 20d Uneven part 20e protrusion 20f recess 21 wires 21a Mesh 21b Central part 21c Peripheral portion 30 Resin cover 31 Outer Sheath 33 Inner sheath 34 Guidewires 40 Resin cover

Claims

1. Inner sheath and, A stent attached to the outer circumference of the inner sheath, An outer sheath is attached so as to cover the outer circumference of the inner sheath and the stent, The system includes a retaining member that restricts the proximal movement of the stent, The outer sheath is mounted so as to be slidable relative to the inner sheath, and is configured to allow the stent to be exposed to the outside. The stent delivery device is characterized in that the stent is a covered stent in which a wire and a resin cover are integrated, and a solid lubricant, which is stearate powder, is attached to the outer circumference of the stent.

2. Within the region demarcated by the wire mesh constituting the stent, The stent delivery device according to claim 1, wherein the solid lubricant is deposited at a higher density on the peripheral portion of the mesh than on the central portion of the area separated by the wire.

3. The outer surface of the stent has a convex portion that protrudes radially outward and a concave portion that is recessed radially inward. The stent delivery device according to claim 1 or 2, wherein the solid lubricant is thicker on the recessed portion than on the convex portion.

4. The stent delivery device according to claim 3, wherein the solid lubricant is also attached to the inner circumferential surface of the end of the stent.

5. The stent delivery device according to claim 4, wherein the solid lubricant is adhered in increasing density in the following order: the outer circumferential surface of the stent, the inner circumferential surface of the end of the stent, and the inner circumferential surface of the central part of the stent.

6. The solid lubricant is formed of calcium stearate, On the outer surface of the stent, 1 cm ２ The stent delivery device according to claim 5, wherein the material is attached at a density of 0.5 mg or more and 2.5 mg or less per unit.

7. The stent delivery device according to claim 6, wherein the portion of the resin cover of the stent to which the solid lubricant is attached is formed of at least PTFE resin.

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