Stent delivery system and method for manufacturing same

Abstract

Provided are a stent delivery system and a method for manufacturing the same, which realize a reduction in the diameter of a balloon catheter to which a stent is crimped. This stent delivery system comprises: a balloon catheter having a balloon that is inflated or deflated by supplying or discharging a fluid; and a stent that is disposed on the balloon and is formed in a cylindrical shape. The stent has the balloon inserted in the cylinder thereof and is fixed on the outer circumferential surface of the balloon. The change ratio of the diameter of the stent is at most 1.54% when a load of 5-10 N per millimeter of the length in the axial direction of the stent is applied inward along the radial direction of the stent.

Description

Stent delivery system and manufacturing method thereof

[0001] The present disclosure relates to a stent delivery system and a method for manufacturing the same.

[0002] Patent Literature 1 discloses a method for manufacturing a stent delivery system in which a stent is crimped onto a balloon catheter. In this method, a prepared stent is pre-shrunk to a second diameter, which has an inner diameter equal to or smaller than the outer diameter of the folded balloon, a folded balloon is inserted into the stent, and pressure is applied radially inward from the outer surface of the stent to shrink the stent to a third diameter, which is the diameter at which crimping is completed. This method is said to be capable of manufacturing a stent delivery system that can prevent the stent from falling off or moving.

[0003] 2012-070912 publication

[0004] In a stent delivery system, if the diameter of the stent crimped onto the balloon of the balloon catheter is large, the balloon catheter may be less able to pass through the lesion. However, conventional techniques such as those disclosed in Patent Document 1 have not been able to sufficiently reduce the diameter. Therefore, there is a need to reduce the diameter of balloon catheters onto which stents are crimped.

[0005] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a stent delivery system and a manufacturing method thereof that enable a balloon catheter having a crimped stent to have a smaller diameter.

[0006] In order to achieve the above object, the stent delivery system and the manufacturing method thereof according to the present disclosure are as follows.

[0007] [1] A stent delivery system comprising: a balloon catheter having a balloon that is inflated or deflated by the supply or discharge of a fluid; and a stent that is disposed on the balloon and formed into a cylindrical shape, wherein the stent has the balloon inserted into its cylinder and is fixed to the outer circumferential surface of the balloon, and wherein a rate of change in diameter of the stent when a load of 5 N or more and 10 N or less per 1 mm of length in the axial direction of the stent is applied inward along the radial direction of the stent is 1.54% or less.

[0008] [2] The stent delivery system according to [1], wherein the stent is formed of a metal alloy, and the metal alloy contains at least one selected from the group consisting of cobalt, chromium, nickel, tungsten, molybdenum, iron, and platinum as an alloy component.

[0009] [3] The stent delivery system according to the above [2], wherein the stent is formed of L-605 alloy, which is an alloy containing cobalt, chromium, tungsten, and nickel.

[0010] [4] The stent delivery system according to any one of [1] to [3] above, wherein the rate of change is 0.08% or more.

[0011] [5] The stent delivery system according to any one of [1] to [4] above, wherein the rate of change is 1.44% or less.

[0012] [6] The stent delivery system according to any one of [1] to [4] above, wherein the rate of change is 0.66% or less.

[0013] [7] The stent delivery system according to any one of [1] to [4] above, wherein the rate of change is 0.60% or less.

[0014] [8] A method for manufacturing a stent delivery system, comprising: a first diameter reduction step in which, with a balloon inserted into a tubular stent, the stent is compressed inward in the radial direction of the stent to reduce the diameters of the stent and the balloon, and then the compression is released; and a second diameter reduction step, which is performed after the first diameter reduction step, the stent is compressed inward in the radial direction of the stent to reduce the diameters of the stent and the balloon, and then the compression is released, wherein the starting diameter of compression in the second diameter reduction step is smaller than the starting diameter of compression in the first diameter reduction step.

[0015] [9] The method for manufacturing a stent delivery system described in [8] above, wherein the first diameter reduction step compresses the stent to a first diameter, and the second diameter reduction step compresses the stent to a second diameter, the second diameter being smaller than the first diameter.

[0016]

[10] The method for manufacturing a stent delivery system according to [8] or [9] above, wherein the second diameter reduction step is repeated two or more times.

[0017]

[11] The method for manufacturing a tent delivery system described in

[10] above, wherein the second diameter in the second diameter reduction step is equal to or smaller than the second diameter in the second diameter reduction step performed immediately before that step.

[0018]

[12] The method for manufacturing a stent delivery system according to any one of [8] to

[10] above, wherein the compression in the second diameter reduction step is performed inward along the radial direction by applying a load of 5 N to 10 N per 1 mm of length in the axial direction of the stent.

[0019]

[13] The method for manufacturing a stent delivery system according to any one of [8] to

[10] above, wherein in the second diameter reduction step, the stent is compressed until the diameter of the stent becomes 3.0 mm or less.

[0020]

[14] A method for manufacturing a stent delivery system described in

[10] or

[11] above, wherein the repetition of the second diameter reduction step is terminated when a rate of change in diameter of the stent when a load of 5 N or more and 10 N or less is applied inward along the radial direction of the stent per 1 mm of length in the axial direction of the stent is 0.60% or less.

[0021] According to the present disclosure, it is possible to provide a stent delivery system and a manufacturing method thereof that realizes a reduction in the diameter of a balloon catheter having a crimped stent.

[0022] FIG. 1 is an explanatory diagram of a stent delivery system. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1. FIG. 3 is a cross-sectional view of a balloon, a stent, a portion of the shaft supporting the balloon, and the surrounding area. FIG. 4 is a development view of a stent. FIG. 5 is an explanatory diagram of the state of a balloon, a stent, and a crimp head before the stent is reduced in diameter during a crimping operation. FIG. 6 is an explanatory diagram of the state of a balloon, a stent, and a crimp head after the stent is reduced in diameter during a crimping operation. FIG. 7 is a graph showing a method of manufacturing a stent delivery system in terms of the relationship between the opening diameter of the crimp head and the elapsed time of the process. FIG. 8 is a cross-sectional view of another stent delivery system.

[0023] A stent delivery system and a manufacturing method thereof according to an embodiment of the present disclosure will be described with reference to the drawings.

[0024] FIG. 1 shows a stent delivery system 200 according to this embodiment.

[0025] Fig. 2 shows a cross-sectional view taken along the line II-II in Fig. 1. First, an outline of the stent delivery system 200 and its manufacturing method will be described.

[0026] As shown in FIG. 1, the stent delivery system 200 comprises a balloon catheter 100 having a balloon 1 that is inflated or deflated by supplying or discharging a fluid, and a stent 2 that is placed on the balloon 1 and formed into a cylindrical shape.

[0027] As shown in Figure 2, the stent 2 has a balloon 1 inserted into its cylinder and is fixed onto the outer circumferential surface of the balloon 1. In other words, the stent 2 is crimped onto the balloon 1. In Figures 1 and 2, the balloon 1 is in a deflated state.

[0028] The stent delivery system 200 can be manufactured by a method for manufacturing a stent delivery system that includes a diameter reduction step in which, with a balloon 1 inserted inside a tubular stent 2 formed in a cylindrical shape, the stent 2 is compressed radially inward to reduce the diameter of the stent 2 and the balloon 1, and then the compression is released.

[0029] The stent delivery system and its manufacturing method will be described in detail below.

[0030] The stent delivery system 200 having a balloon catheter 100 shown in Figure 1 is a medical device used in a procedure (e.g., PCI) to dilate a lesion (stenosis) formed in a biological lumen such as a blood vessel. In a procedure using the stent delivery system 200, an operator inserts a stent 2 crimped onto a balloon 1 disposed at the distal end of a shaft 5 into the biological lumen. The operator expands the balloon 1 on the inner periphery of a stenosis formed in the biological lumen, thereby expanding the stent 2 together with the balloon 1. The operator places the expanded stent 2 on the inner periphery of the stenosis, thereby maintaining the stenosis.

[0031] The balloon catheter 100 is used to deliver the stent 2 to the narrowed area, but it can also be configured to be used for the purpose of treating and improving narrowed areas formed in biological organs such as blood vessels, bile ducts, tracheas, esophagus, other digestive tracts, urethras, ear and nose cavities, and other organs.

[0032] As shown in Figures 1 to 3, the balloon catheter 100 has a flexible, elongated shaft 5, a balloon 1 disposed at the distal end of the shaft 5, and a hub 8 (see Figure 1) disposed at the proximal end of the shaft 5. In a stent delivery system 200 (see Figure 1), a stent 2 is crimped onto the balloon 1 of the balloon catheter 100. Note that Figure 3 is a cross-sectional view taken along the line III-III in Figure 1, showing the balloon 1 in an expanded state, the stent 2, the portion of the shaft 5 supporting the balloon 1, and the surrounding area. Figure 3 shows a cross-section overlapping the axial center of the shaft 5.

[0033] The balloon catheter 100 may be provided with a guidewire port 51 near the distal end of the shaft 5 through which a guidewire or the like can be led out.

[0034] 3, the shaft 5 has an inner tube 7 formed with a lumen 71 through which a guidewire or the like is inserted, and an outer tube 6 forming a lumen 61 between the inner tube 7 and the outer tube 6, through which a pressurized medium (e.g., a fluid such as physiological saline or a contrast agent) can flow. By inserting the inner tube 7 into the outer tube 6, the shaft 5 has a double-tube structure in which the inner tube 7 and the outer tube 6 are concentrically arranged.

[0035] The shaft 5 supports the balloon 1. The inner tube 7 of the shaft 5 passes through the balloon 1. The shaft 5 supplies the above-mentioned fluid to the space inside the balloon 1 or discharges the fluid from the balloon 1, thereby inflating or deflating the balloon 1.

[0036] The balloon 1 is liquid-tightly and air-tightly joined to the distal end of the inner tube 7 by welding or the like. The distal end of the balloon 1 in the extension direction of the shaft 5 is joined to the inner tube 7 by fusion or the like. The proximal end of the balloon 1 in the extension direction of the shaft 5 is liquid-tightly and air-tightly joined to the outer tube 6 by fusion or the like. In FIG. 3 , the portion of the balloon 1 where the distal end of the balloon 1 and the inner tube 7 are joined is shown as a distal joint 17. The portion of the balloon 1 where the proximal end of the balloon 1 and the outer tube 6 are joined is shown as a proximal joint 16. The diameter D of the proximal joint 16 is larger than the diameter (outer diameter) of the distal joint 17.

[0037] A distal tip 79 can be attached to the distal end of the inner tube 7. The distal tip 79 prevents damage to a biological organ (such as the inner wall of a blood vessel) when the distal end of the balloon catheter 100 comes into contact with the biological organ. The distal tip 79 can be made of a resin material that is more flexible than the inner tube 7.

[0038] A pressurized medium can flow into the space between the balloon 1 and the inner tube 7 (hereinafter referred to as the internal space).

[0039] The balloon 1 is inserted into a biological lumen and is folded to maintain passability through the biological lumen until it reaches a stricture in the biological lumen.

[0040] The balloon 1 expands when a pressurized medium is introduced into the internal space (see FIG. 3). When the balloon 1 expands, the balloon catheter 100 expands the diameter of the balloon 1 so that a portion of the balloon 1 presses the stent 2 against a stricture formed in a biological lumen. The stent 2 is placed in the expanded state by the balloon 1, pressing the stricture open.

[0041] The balloon 1 is inserted into a biological lumen and is folded in a deflated state to maintain its passability through the biological lumen until it reaches a narrowed portion of the biological lumen (see Figure 2). The deflated state of the balloon 1 refers to a state in which no pressurized medium is flowing into the internal space.

[0042] As shown in Figure 2, the balloon 1 may be folded into three or more sections along the circumferential direction (direction C in Figure 2) of the inner tube 7. In Figure 2, each section of the balloon 1 is folded to have a wing base 11 adjacent to the inner tube 7 and aligned along the inner tube 7, and a wing 12 superimposed on the wing base 11.

[0043] The blade portions 12 in each region are superimposed on the blade base 11 along the same circumferential direction. The blade portions 12 have inner portions 12a superimposed adjacent to each other on the blade base 11, and outer portions 12b superimposed on the inner portions 12a.

[0044] The boundary between the blade base 11 and the blade portion 12, i.e., the boundary between the blade base 11 and the blade portion 12 superposed on the blade base 11, is a fold portion 13 that runs along the axial direction (direction Z in FIG. 3 ) of the inner tube 7. The fold portion 13 is located more inward than the outer portion 12 b in the radial direction (direction R in FIG. 3 ) of the inner tube 7.

[0045] The boundary between the inner portion 12a and the outer portion 12b, at the end of the inner portion 12a opposite the fold portion 13 in the circumferential direction of the inner tube 7, is a fold portion 14 that runs along the axial direction of the inner tube 7.

[0046] As shown in FIG. 3 , the balloon 1 has an expanded size, for example, of 1 to 20 mm, preferably 1 to 10 mm, in outer diameter of the straight portion 10, and 5 to 100 mm, preferably 5 to 60 mm, in length in the axial direction (direction Z). The distal joint portion 17 has an outer diameter of 0.3 to 1.5 mm, preferably 0.5 to 1.3 mm, and an axial length of 0.5 to 5 mm, preferably 0.5 to 3 mm. The proximal joint portion 16 has an outer diameter of 0.5 to 1.8 mm, preferably 0.6 to 1.3 mm, and an axial length of 1 to 8 mm, preferably 1 to 6 mm. The distal tapered portion 19 and the proximal tapered portion 18 each have an axial length of 1 to 10 mm, preferably 3 to 7 mm. In this embodiment, the term "A to B" (where A and B are positive real numbers) means greater than or equal to A and less than or equal to B. For example, 1 to 20 mm means greater than or equal to 1 mm and less than or equal to 20 mm.

[0047] For example, an organic polymer material can be used as the material for forming the balloon 1. Specific examples of the organic polymer material for forming the balloon 1 include polymer materials such as polyolefin (e.g., polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of two or more of these), polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, and fluororesin, as well as mixtures of these materials, and elastic resin materials such as two or more of the above polymer materials, with polyamide-based resins being particularly preferred as the main material.

[0048] The stent 2 is a member formed into a cylindrical shape as shown in FIG. 3 . The stent 2 is formed, for example, from a metal alloy. The stent 2 is, for example, a cylindrical wire mesh member. The balloon 1 is inserted into the cylindrical interior of the stent 2. The stent 2 is fixed (crimped) onto the outer surface of the balloon 1. When the stent 2 is fixed onto the outer surface of the balloon 1, the radial direction of the stent 2 and the radial direction of the inner tube 7 are the same. Hereinafter, the radial direction of the stent 2 and the radial direction of the inner tube 7 may be collectively referred to simply as the radial direction.

[0049] Figure 4 shows a developed view of the stent 2. As shown in Figure 4, the stent 2 has a plurality of annular portions 21 that extend in a wave-like pattern in the circumferential direction of the inner tube 7 (see Figure 2) and are arranged at predetermined intervals in the axial direction of the inner tube 7, and a plurality of link portions 22 that connect adjacent annular portions 21 in the axial direction. The stent 2 is configured in a cylindrical shape. A balloon 1 is inserted inside the cylinder of the stent 2 (see Figures 2 and 3).

[0050] The stent 2 is designed to remain fixed (crimped) on the outer surface of the balloon 1 and to maintain its expanded diameter once expanded by the balloon 1. Therefore, a material that undergoes plastic deformation upon expansion of the balloon 1 and maintains its shape can be selected as the material for the stent 2.

[0051] The metal alloy forming the stent 2 may contain at least one selected from the group consisting of cobalt, chromium, nickel, tungsten, molybdenum, iron, and platinum as an alloy component. A particularly suitable metal alloy forming the stent 2 is the L-605 alloy, which is an alloy containing cobalt, chromium, tungsten, and nickel.

[0052] The expanded diameter of the stent 2 is not particularly limited, but is, for example, 1 to 30 mm in outer diameter. The stent 2 according to this embodiment is used to treat lesions such as strictures and obstructions that occur in blood vessels, bile ducts, tracheas, esophagus, urethra, or other biological lumens. The expanded diameter of the stent 2 is set according to the diameter of the target lesion.

[0053] The diameter of the stent 2 before expansion and when attached to the balloon catheter 100 is not particularly limited, but is, for example, 0.5 to 3 mm in outer diameter. If the diameter of the lumen in which the target lesion exists is small, the diameter of the stent when attached to the delivery catheter must also be small.

[0054] The diameter of the stent 2 before expansion and before attachment to the balloon catheter 100 is not particularly limited, but may be, for example, 1 to 5 mm in outer diameter. The stent 2 is manufactured using known techniques, for example, by removing unnecessary portions from a pipe material other than the regions that will become the struts, followed by polishing. The stent 2 is then contracted and attached to the balloon catheter 100. In this case, the outer diameter of the stent 2 before attachment to the balloon catheter 100 is the outer diameter of the stent 2 after polishing, which is approximately the same as the outer diameter of the pipe material.

[0055] The thickness of the stent 2 is not particularly limited, but is, for example, 0.05 to 1 mm.

[0056] The line width of the stent 2 is not particularly limited, but is, for example, 0.05 to 1 mm.

[0057] The angle of the curved portion (hereinafter referred to as the curved portion) in the annular portion 21 of the stent 2 is not particularly limited, but is, for example, 0° to 150° (preferably 10° to 120°) during uniform expansion.

[0058] The axial length of the link portion 22 is not particularly limited, but is, for example, 0.05 to 50 mm. The link portion 22 may have a component extending in the circumferential direction, but in that case, the circumferential length is not particularly limited, but is, for example, 0.05 to 50 mm.

[0059] The surface of the stent 2 may be coated with a drug such as an immunosuppressant, thereby preventing restenosis in the lumen of the living body after the stent is placed. Because stress concentration occurs at the curved portion during expansion, which may cause the drug to peel off, the curved portion does not need to be coated with a drug.

[0060] Also, as in a stent graft, a cover member made of a fibrous material, a sheet-like material, or the like may be disposed on the outer or inner surface of the stent 2. The cover member may have high or low permeability to liquids and gases, or may be impermeable.

[0061] The stent 2 is crimped onto the balloon 1 as follows. Below, a method for crimping the stent 2 onto the balloon 1 by caulking (hereinafter referred to as the crimping method) will be described as a method for manufacturing the stent delivery system 200.

[0062] The crimping method according to this embodiment includes a first diameter reduction step in which, with the balloon 1 inserted inside the stent 2, the stent 2 is compressed inward in the radial direction of the stent 2 to reduce the diameters of the stent 2 and the balloon 1, and then this compression is released. The crimping method according to this embodiment may also include a second diameter reduction step, which is performed after the first diameter reduction step, in which the stent 2 is compressed inward in the radial direction of the stent 2 to reduce the diameters of the stent 2 and the balloon 1, and then this compression is released. The first diameter reduction step and the second diameter reduction step are operations for crimping the stent 2 to the balloon 1.

[0063] The first diameter reduction step is an operation including initial compression and release of the stent 2. In the first diameter reduction step, folds 13, 14 (see FIG. 2) are formed in the balloon 1 (to give the balloon 1 a folded shape). The second diameter reduction step is an operation including compression and release of the stent 2 after the first diameter reduction step. The second diameter reduction step may be repeated two or more times. The operation of reducing the diameter of the stent 2 and the balloon 1 in the first diameter reduction step and the operation of reducing the diameter of the stent 2 and the balloon 1 in the second diameter reduction step are basically the same operation, but have some differences.

[0064] The first diameter reduction step includes a first compression step in which the stent 2 is compressed radially inward to reduce the stent 2 to a first diameter, and a first release step in which the compression is released after the first compression step.

[0065] The first diameter reduction step may include a first maintaining step of maintaining the stent 2 at a first diameter. That is, the first diameter reduction step may include a first compression step of compressing the stent 2 inward in the radial direction of the stent 2 to reduce the stent 2 to a first diameter, a first maintaining step of maintaining the stent 2 at the first diameter, and a first releasing step of releasing the compression after the first maintaining step. The first compression step, first maintaining step, and first releasing step are performed in this order.

[0066] The second diameter reduction step includes a second compression step in which the stent 2 is compressed radially inward to reduce the stent 2 to a second diameter, and a second release step in which the compression is released after the second compression step. By performing the second diameter reduction step in addition to the first diameter reduction step, the folds 13, 14 (see FIG. 2 ) of the balloon 1 become more even, or the space within the balloon 1 is reduced, thereby enabling the stent 2 to be made thinner than when only the first diameter reduction step is performed. Furthermore, the second diameter reduction step increases the amount of clamping of the stent 2 by the balloon 1, thereby more firmly securing the stent 2 to the balloon 1. In other words, the retention of the stent 2 on the balloon 1 in the balloon catheter 100 is improved.

[0067] Hereinafter, the improvement in the retention force that holds the stent 2 to the balloon 1 in the balloon catheter 100 may be simply referred to as "improved retention."

[0068] The second diameter reduction step is preferably repeated two or more times. This results in a thinner diameter or improved retention. If the second diameter reduction step is repeated three to 20 times, sufficient thinning and improved retention can be achieved.

[0069] The second diameter reduction step may include a second maintaining step of maintaining the stent 2 at the second diameter. That is, the second diameter reduction step may include a second compression step of compressing the stent 2 radially inward to reduce the stent 2 to the second diameter, a second maintaining step of maintaining the stent 2 at the second diameter, and a second releasing step of releasing the compression after the second maintaining step. The second compression step, second maintaining step, and second releasing step are performed in this order.

[0070] The diameter of the stent 2 in the first diameter reduction step (first compression step) and the second diameter reduction step (first compression step) may be reduced by crimping using a crimp head 9 of a crimping device, as shown in Figures 5 and 6. Figures 5 and 6 are explanatory diagrams showing the image of the state of the balloon 1, the stent 2, and the crimp head 9 before and after the diameter of the stent 2 is reduced during the crimping operation, respectively.

[0071] The crimp head 9 has a straight-bore hole 90 whose inner diameter can be reduced or expanded. The diameter of the stent 2 can be reduced by inserting the balloon 1 to which the stent 2 is fixed into the hole 90 and reducing the diameter of the hole 90 (hereinafter sometimes referred to as the opening diameter of the crimp head 9), thereby pressing, i.e., compressing, the outer circumferential surface of the stent 2 in the radial direction. The stent 2 can be released from compression by expanding the opening diameter of the crimp head 9.

[0072] The diameter of the stent 2 in the first diameter reduction step and the second diameter reduction step is preferably reduced by applying a load of 5 N to 10 N per 1 mm of length in the axial direction of the stent 2 (direction Z in FIG. 3 ) inward along the radial direction. This allows the stent 2 to be crimped to the balloon 1 without damaging the balloon 1, and reduces the diameter (outer diameter) of the stent 2 and the balloon 1. Hereinafter, reducing the diameter of the stent 2 may be simply referred to as "diameter reduction" or "diameter reduction." The concepts of "diameter reduction" and "diameter reduction" include reducing the diameter of the stent 2 and the balloon 1. In the following description, when simply referring to the diameter of the stent 2, this refers to the outer diameter of the stent 2.

[0073] In the first diameter reduction step, the opening diameter of the crimp head 9 may be reduced to a first diameter. This allows the diameter of the stent 2 to be reduced until the diameter of the stent 2 reaches the first diameter.

[0074] The first maintaining step is a step in which, after the diameter of the stent 2 reaches the first diameter in the first compression step, compression is stopped in this state and the diameter of the stent 2 is maintained at the first diameter for a certain period of time. This increases the amount of clamping of the balloon 1 into the stent 2, thereby more firmly fixing the stent 2 to the balloon 1. In other words, retention is improved. In the first maintaining step, a load of 5 N to 10 N per 1 mm of length in the axial direction of the stent 2 may be applied inward along the radial direction to the stent 2.

[0075] In the second diameter reduction step, the opening diameter of the crimp head 9 may be reduced to the second diameter. That is, in the second diameter reduction step, the stent 2 may be compressed until the diameter of the stent 2 becomes the second diameter. In this way, the diameter of the stent 2 can be reduced until the diameter of the stent 2 becomes the second diameter.

[0076] The second maintaining step is a step of stopping the compression in this state after the diameter of the stent 2 reaches the second diameter in the second compression step, and maintaining the diameter of the stent 2 at the second diameter for a certain period of time, thereby improving retention. In the second maintaining step, a load of 5 N to 10 N per 1 mm of axial length of the stent 2 may be applied inward along the radial direction to the stent 2.

[0077] The second diameter may be equal to or smaller than the first diameter. That is, the second diameter may be equal to the first diameter. Alternatively, the second diameter may be smaller than the first diameter. The second diameter may be, for example, 3.0 mm or less. Hereinafter, the target diameter reduction value in each diameter reduction step, such as the first diameter and the second diameter, may be referred to as the final diameter.

[0078] The final diameter is preferably equal to or smaller than the diameter D of the proximal junction 16. The final diameter is preferably smaller than the diameter D of the proximal junction 16. This allows for a smaller diameter. For example, it may be possible to provide a stent delivery system 200 in which the diameter of the stent 2 is equal to or smaller than the diameter D of the proximal junction 16 but equal to or larger than the diameter of the inner tube 7. Note that when the final diameter is equal to or smaller than the diameter D of the proximal junction 16, it is preferable that the stent 2 and the outer tube 6 do not overlap in the radial direction.

[0079] As described above, the second diameter reduction step may be repeated two or more times. In this case, the second diameter of one second diameter reduction step may be smaller than the second diameter of the second diameter reduction step performed immediately before it. That is, the final diameter may be successively smaller as the second diameter reduction step is repeated.

[0080] The first and second release steps are steps in which the stent 2 is compressed to its final diameter and then released. Here, releasing the compression means ending the pressing and allowing the stent 2 and the balloon 1 to relax. Specifically, this is done by enlarging the opening diameter of the crimp head 9 from the final diameter. Enlarging the opening diameter of the crimp head 9 increases the diameter of the stent 2 and the balloon 1 (so-called recoil). Note that recoil refers to the natural expansion of the stent 2 in diameter by the amount of deformation due to elastic deformation when the stent 2 is contracted.

[0081] After the first diameter reduction step (after the first release step), the diameter of the stent 2 and balloon 1 (the diameter after recoil) is smaller than at the start of the first diameter reduction step. Therefore, when releasing the compression in the first diameter reduction step, i.e., in the first release step, the diameter of the hole 90 at the end of the first release step (hereinafter referred to as the "first release diameter") needs to be smaller than the diameter of the hole 90 at the start of the first diameter reduction step (hereinafter referred to as the "start diameter"). The "start diameter" refers to the opening diameter of the crimp head 9 at the time when the inner surface of the hole 90 comes into contact with the entire outer peripheral surface of the stent 2, in other words, the opening diameter of the crimp head 9 at the time when compression of the stent 2 begins.

[0082] Furthermore, as described above, since the diameter of the stent 2 and balloon 1 (the diameter after recoil) after the first diameter reduction step is smaller than the diameter at the start of the first diameter reduction step, the opening diameter of the crimp head 9 (the diameter of the hole 90, hereinafter referred to as the second starting diameter) at the start of the second diameter reduction step is smaller than the starting diameter. In this embodiment, the second starting diameter of the second diameter reduction step, which is performed first, is the same as the first release diameter.

[0083] The second starting diameter is preferably equal to or smaller than the diameter D of the base-end joint 16. The second starting diameter is preferably less than the diameter D of the base-end joint 16. This allows for a thinner diameter. It may also be possible to shorten the manufacturing time of the stent delivery system 200. Note that, when the second starting diameter is equal to or smaller than the diameter D of the base-end joint 16, it is preferable that the stent 2 and the outer tube 6 do not overlap in the radial direction.

[0084] After the second diameter reduction step (after the second release step), the diameter (post-recoil diameter) of the stent 2 and balloon 1 is smaller than the second starting diameter of the second diameter reduction step. Therefore, when releasing the compression in the second diameter reduction step, i.e., in the second release step, the diameter of the hole 90 at the end of the second release step (hereinafter referred to as the second release diameter) can be equal to or smaller than the diameter of the hole 90 at the start of the second diameter reduction step (hereinafter referred to as the second starting diameter).

[0085] In addition, in the second release step of the final second diameter reduction step, the opening diameter of the crimp head 9 may be expanded to the same or greater than the starting diameter to make it easier to remove the stent 2 and balloon 1 from the crimp head 9.

[0086] As described above, the second diameter reducing step may be repeated two or more times, but the repetition of the second diameter reducing step may be terminated in the following cases:

[0087] For example, the repetition of the second diameter reduction step may be terminated when the diameter of the stent 2 after recoil that occurs after the second diameter reduction step becomes equal to or less than a predetermined value (for example, 1.02 mm). In other words, once the diameter of the stent 2 has been reduced to the predetermined target value, the repetition of the second diameter reduction step may be terminated. This allows for efficient diameter reduction.

[0088] The repetition of the second diameter reduction step may be terminated when the rate of change (rate of reduction) in the diameter of the stent 2 when a load of 5 N to 10 N per 1 mm of length in the axial direction of the stent 2 is applied inward along the radial direction of the stent 2 is equal to or less than a predetermined amount x (%). This allows for efficient diameter reduction.

[0089] Here, the rate of change in the diameter of the stent 2 is the absolute value of the difference Δd obtained by subtracting the diameter d2 of the stent 2 after the application of the load from the diameter d1 of the stent 2 before the application of the load, divided by the diameter d1 and multiplied by 100.

[0090] In addition, when the second compression step in the second diameter reduction step is performed by applying a load of 5 N or more and 10 N or less per 1 mm of axial length of the stent 2 in an inward direction along the radial direction to the stent 2, the diameter d1 is the diameter of the stent 2 immediately before the start of the second diameter reduction step, and the diameter d2 is the diameter of the stent 2 after recoil that occurs after the second diameter reduction step.

[0091] The predetermined amount x is 1.54% or less, preferably 1.44% or less, more preferably 0.66% or less, and even more preferably 0.60% or less. The predetermined amount x is allowed to be 0.08% or more.

[0092] In addition, when the diameter of stent 2 is reduced in the second diameter reduction step with a load of 5 N or more and 10 N or less per 1 mm of length in the axial direction of stent 2, the amount of reduction in the diameter of stent 2 in that step corresponds to the difference Δd, and diameter d2 is the diameter of stent 2 immediately after that step.

[0093] In the crimping method according to this embodiment, a pressurizing step may be performed in the process of crimping the stent 2 to the balloon 1, in which a fluid is supplied to the balloon 1 to inflate it and press the outer circumferential surface of the balloon 1 against the inside of the stent 2. The pressurizing step increases the amount of clamping of the balloon 1 into the stent 2, improving retention. In addition, the adhesion between the inner surface of the stent 2 in the radial direction and the outer surface of the balloon 1 is improved, improving retention.

[0094] The pressurizing step may be performed before the first diameter reducing step, during the first diameter reducing step, or during the second diameter reducing step. For example, the pressurizing step may include a pre-pressurizing step performed before the start of the first diameter reducing step (first compression step), an intermediate pressurizing step performed during the first compression step, a post-pressurizing step (first post-pressurizing step) performed during the first maintaining step, and a post-pressurizing step (second post-pressurizing step) performed during the second maintaining step.

[0095] The pressurizing step preferably includes a pre-pressurizing step, a middle pressurizing step, and a first post-pressurizing step. This effectively improves retention. In this case, the pre-pressurizing step, the middle pressurizing step, and the first post-pressurizing step are preferably a series of pressurizing steps that continue from before the start of the first compression step until during the first maintaining step. This effectively improves retention. Hereinafter, the series of pressurizing steps that continue from before the start of the first compression step until during the first maintaining step may be referred to as the first pressurizing step.

[0096] The pressurizing step preferably includes a second post-pressurizing step, which improves retention.

[0097] The pressurizing step may include a first pressurizing step and a second post-pressurizing step, which may further improve retention.

[0098] When a pressurizing step is performed, it is preferable to repeat the second diameter reduction step two or more times. This may improve retention. When a first pressurizing step or a second post-pressurizing step is performed, it is preferable to further perform a second diameter reduction step without a pressurizing step after these pressurizing steps. It is preferable that the second diameter reduction step without a pressurizing step performed after a pressurizing step is repeated two or more times, preferably three to five times. This may further improve retention.

[0099] Figure 7 shows a graph illustrating an example of the above-described manufacturing method (crimping method) for the stent delivery system, showing the relationship between the opening diameter of the crimp head 9 of the crimping device (see Figures 5 and 6 above) and the elapsed time of the process. In the graph of Figure 7, the vertical axis represents the opening diameter of the crimp head 9 (opening diameter in Figure 7), and the horizontal axis represents the elapsed time of the process in the manufacturing method for the stent delivery system. In the graph of Figure 7, the solid line L represents the opening diameter of the crimp head 9.

[0100] In Fig. 7, symbol S1 indicates a first diameter reduction step, symbol S11 indicates a first compression step, symbol S12 indicates a first maintenance step, symbol S13 indicates a first release step, and symbol Q1 indicates the start of the first diameter reduction step.

[0101] In Fig. 7, the symbol S2 indicates the second diameter reduction step. In the example shown in Fig. 7, the second diameter reduction step is performed N+M times (where N and M are natural numbers). Symbol S2 １ Symbol S2 such as ｉ The symbol S21 indicates the second compression step. The symbol S22 indicates the second maintaining step. The symbol S23 indicates the second releasing step. The symbol Q2 ｉ indicates the start of the i-th second diameter reduction step.

[0102] The second starting diameter in the first (initial) second diameter reduction step is the same as the first released diameter in the first diameter reduction step. In the example shown in Figure 7, the final diameter (second diameter) in the second diameter reduction step is the same as the final diameter (first diameter) in the first diameter reduction step. Also, in the example shown in Figure 7, the second released diameters in the second diameter reduction steps except for the last one are the same as the second starting diameter in the second diameter reduction step. The second released diameter in the last second diameter reduction step is set to be equal to or larger than the first starting diameter, and crimping is completed.

[0103] In Fig. 7, symbol P1 indicates a first pressurizing step. Symbol P2 indicates a second post-pressurizing step. In the example shown in Fig. 7, the first pressurizing step includes a pre-pressurizing step, a middle pressurizing step, and a first post-pressurizing step. The first pressurizing step is a series of pressurizing steps that continues from before the start of the first compression step until during the first maintenance step.

[0104] In the example shown in FIG. 7, the second diameter reduction step (S2 Ｎ After that, the second diameter reduction step (S2) is performed in which the second post-pressurization step is not performed. Ｎ＋１ ~S2 Ｎ＋Ｍ ) has been performed M times.

[0105] EXAMPLES Hereinafter, a stent delivery system and a manufacturing method thereof will be described based on examples.

[0106] Example 1 In this example, a balloon mounted on a shaft having an inner tube and an outer tube was inserted into a stent having a diameter (outer diameter) of 2.0 mm according to the crimping method described above. The stent and balloon were then inserted into the crimping head of a crimping device and crimped together to crimp the stent to the balloon. The diameter of the crimped stent was then measured. The balloon and stent were crimped using an "Ultimaster Nagomi (registered trademark)" crimper manufactured by Terumo Corporation.

[0107] The balloon used in this example has its proximal end fused to the outer periphery of the outer tube, with a diameter (outer diameter) of 1.0 mm at the proximal end. The distal end of the balloon has its distal end fused to the outer periphery of the inner tube, with a diameter (outer diameter) of 0.6 mm at the distal end. The balloon was pre-folded to have three wings before insertion into the stent. This balloon was made of polyamide resin. The outer diameter of the inner tube was 0.25 mm, and the outer diameter of the outer tube was 0.65 mm.

[0108] The stent used in this example was a wire mesh stent made of L-605 alloy.

[0109] Before starting the first diameter reduction step, the stent was temporarily attached to the balloon by inserting the balloon, which was placed on the shaft, into the stent tube, and then inserting the stent and balloon into the crimp head of the crimping device and lightly crimping them together.

[0110] The starting diameter in the first diameter reduction step is the same as the outer diameter of the stent after the temporary fixing, and is smaller than the diameter (2 mm) of the stent before the temporary fixing.

[0111] The final diameter in the first compression step was 0.48 mm, which was smaller than the diameter of the base-end side joint portion.

[0112] The first compression step was performed by gradually reducing the hole diameter of the crimp head, applying a load of 5 to 10 N per 1 mm of axial length of the stent inward along the radial direction of the stent, until the final diameter was reached. The first compression step took approximately 30 seconds. In this example, the first maintenance step was omitted. After the first compression step, a first release step was performed. The first release diameter was 1.2 mm, which was larger than the diameter of the proximal joint.

[0113] After the first diameter reduction step, the second diameter reduction step was repeated 15 times. The second starting diameter in all second diameter reduction steps was 1.2 mm, the same as the first released diameter. That is, the second released diameter in the first to fourteenth second diameter reduction steps was 1.2 mm, the same as the first released diameter. The second released diameter in the fifteenth second diameter reduction step was larger than the starting diameter. In this example, the second maintaining step was omitted in all second diameter reduction steps.

[0114] The second compression step in the second diameter reduction step was carried out in the same manner as the first compression step, by gradually reducing the hole diameter of the crimp head, while applying a load of 5 to 10 N per 1 mm of axial length of the stent inward along the radial direction of the stent, until the final diameter was reached. Each second compression step took approximately 20 seconds.

[0115] After the first diameter reduction step and each second diameter reduction step, the diameter of the stent crimped onto the balloon was measured. The measurement results are shown in Table 1. The number of crimping operations in Table 1 is calculated by counting the first diameter reduction step as the first operation and the second diameter reduction step and subsequent operations as the second operation and subsequent operations. In other words, in Table 1, each compression and release in the first diameter reduction step and the second diameter reduction step constitute one cycle of the crimping operation, and the cumulative number of such crimping operations is shown as the number of crimping operations. The diameter of the first crimping operation in Table 1 is the diameter of the stent immediately after the first diameter reduction step. The diameter of the second crimping operation in Table 1 is the diameter of the stent immediately after the first second diameter reduction step, and the same applies for the third and subsequent operations.

[0116]

[0117] Table 1 also shows the percentage change (%) before and after each crimping operation. This percentage change is calculated by dividing the absolute value (absolute value in Table 1) of the difference (the difference in Table 1) obtained by subtracting the diameter of the stent after each crimping operation from the diameter of the stent immediately before each crimping operation by the diameter of the stent immediately before the crimping operation, and multiplying the result by 100. For example, the percentage change after the third crimping operation is calculated by dividing the absolute value of the difference (the diameter of the stent immediately before the third crimping operation, i.e., after the second crimping operation, minus the diameter of the stent after the third crimping operation) by the diameter of the stent after the second crimping operation, and multiplying the result by 100.

[0118] As shown in Table 1, the rate of change decreases to approximately 1.44% after the third crimping cycle, indicating that the stent is thinned. Therefore, in order to thin the stent, it is considered necessary for the rate of change to be at least 1.54% or less. For appropriate thinning of the stent, it is considered preferable for the rate of change to be 1.44% or less. Furthermore, when the stent is sufficiently thinned, the balloon is sufficiently sandwiched between the stent 2, and it can be determined that the balloon retention has reached a level required for practical use.

[0119] In this example, the final diameter of the first compression step is 0.48 mm, which is smaller than the diameter of the base-end joint, and is therefore smaller than the diameter of the base-end joint. Setting the final diameter of the first compression step in this manner is also thought to have contributed to the thinning of the stent after the third crimping.

[0120] Furthermore, in this embodiment, the final diameter of the second compression step is set to 0.48 mm, which is smaller than the diameter of the base-end joint, and is therefore smaller than the diameter of the base-end joint. Setting the final diameter of the second compression step in this manner is also thought to have contributed to the thinning of the stent after the third crimping.

[0121] After the fourth crimping, the rate of change reaches approximately 0.66% or less, and the stent is sufficiently thinned. Therefore, it is considered that the stent can be sufficiently thinned if the rate of change is 0.66% or less.

[0122] After the fifth crimping, the change rate reached approximately 0.60% or less, and the stent was further thinned. Therefore, it is believed that a change rate of 0.60% or less can further thin the stent. Furthermore, after the ninth crimping, the change rate reached 0.08% or more.

[0123] Considering the rate of change after the fifth crimping, it is believed that sufficient thinning of the stent can be achieved even if the repetition of the second diameter reduction step is terminated when the rate of change reaches 0.60% or less.

[0124] When considering the number of times of crimping, the rate of change becomes roughly constant after the fifth crimping, and even after the ninth crimping. Therefore, it is considered that performing the second diameter reduction step four or more times, preferably eight or more times, is sufficient for sufficient thinning, and performing it nine or more times is sufficient.

[0125] For example, if the second diameter reduction step is performed four or more times and the rate of change is controlled to 0.60% or less, it is believed that reliable thinning can be achieved.

[0126] The final diameter of the stent was less than the diameter of the proximal junction and greater than the diameter of the inner tube.

[0127] Furthermore, no pinholes were observed in the balloon in the final second diameter reduction step.

[0128] Example 2 In Example 2, the stent and balloon lots were changed, and the procedure was otherwise the same as in Example 1, up to the 15th second reduction step, and the stent was crimped onto the balloon. In Example 2, the diameter and retention (holding force) of the stent after the 15th second reduction step were measured. In Example 2, six crimped stents were manufactured using the same manufacturing method, and the average diameters of five of the stents and the average retention (holding force) of four of the stents were obtained. The diameter variation and retention variation of the crimped stents were also evaluated based on the standard deviation. Table 2 shows the average diameter (mm), standard deviation of diameter (mm), average retention (N), and standard deviation of retention (N) of the crimped stents.

[0129]

[0130] The retention is the retention force of the stent when it is crimped onto the balloon. In this example, the retention is a value measured in accordance with ASTM F2394-07 (initial peak displacement force described in Readpved 2022), and is the tensile force at which the stent falls off the balloon when the stent is pulled in the axial direction relative to the balloon.

[0131] Example 3 differs from Example 2 in that the second maintaining step was performed only during the 15th second diameter reduction step, and that a pressurizing step was performed during this second maintaining step, in which a fluid was supplied to the balloon to inflate it and press the balloon against the inside of the stent. Otherwise, the same procedures as in Example 2 were carried out to obtain the average stent diameter and the average retention (retention force), and the variation therein was also evaluated. Table 2 also shows these results.

[0132] In this example, the second maintaining step in the 15th second diameter reduction step was performed for 30 seconds. That is, in the 15th second diameter reduction step, the hole diameter of the crimping device was maintained at the final diameter for 30 seconds as the second maintaining step after the compression step. After the second maintaining step, a second releasing step was performed to increase the hole diameter of the crimping device from the initial diameter.

[0133] The pressurization step started simultaneously with the start of the second maintaining step and ended simultaneously with the end of the second maintaining step. That is, the pressurization step was carried out for 30 seconds. During the pressurization step, the pressure inside the balloon was pressurized to 1.4 MPa and maintained, and at the end of the pressurization step, the pressure inside the balloon was released.

[0134] Example 4 Example 4 was performed in the same manner as Example 3 up to the second maintaining step in the 15th second diameter reduction step and the pressurizing step performed simultaneously with this second maintaining step. Thereafter, unlike Example 3, the second maintaining step in the 15th second diameter reduction step and the pressurizing step performed simultaneously with this second maintaining step were performed, followed by four more repeated second diameter reduction steps. The final (19th) second diameter reduction step was performed in the same manner as the final (15th) second diameter reduction step in Example 2. The stents crimped onto the balloon were evaluated by obtaining the average stent diameter and average retention (retention force) values ​​in the same manner as Examples 2 and 3, and evaluating the variability therein. Table 2 also shows these results.

[0135] As shown in Table 2, a comparison of Examples 2 to 4 shows that the stent diameter was reduced regardless of whether or not a pressurizing process was performed. However, Examples 3 and 4, in which a pressurizing process was performed, had higher retention values ​​than Example 2, in which a pressurizing process was not performed, demonstrating the effect of improving retention. Furthermore, Examples 3 and 4, in which a pressurizing process was performed, also showed reduced retention variation compared to Example 2, in which a pressurizing process was not performed, demonstrating the effect of stabilizing retention.

[0136] These results suggest that the pressurization process increased the amount of the balloon clamped to the stent, improving retention. It is also believed that the pressurization process improved the adhesion between the inner surface of the stent in the radial direction and the outer surface of the balloon, improving retention.

[0137] Furthermore, when considering whether or not a second diameter reduction step was performed after the pressurizing step, Example 4, in which a second diameter reduction step was performed after the pressurizing step, had a higher retention value than Example 3, in which a second diameter reduction step was not performed after the pressurizing step, and it can be seen that the effect of improving retention can be obtained by performing a second diameter reduction step without a pressurizing step after a second diameter reduction step with a pressurizing step.

[0138] These results suggest that the second diameter reduction step after the pressurization step further increased the amount of clamping of the balloon into the stent, improving retention. Also, the second diameter reduction step after the pressurization step further improved the adhesion between the radially inner surface of the stent and the outer surface of the balloon, improving retention.

[0139] In this way, it is possible to provide a stent delivery system and a manufacturing method thereof that enable a balloon catheter having a crimped stent to have a smaller diameter.

[0140] [Other Embodiments] (1) In the above embodiment, the stent delivery system 200 (see FIG. 1, etc.) has been described as an example in which the diameter of the stent 2 exceeds the diameter D of the proximal bond 16 when the balloon 1 is folded (before the stent 2 is expanded). However, as shown in FIG. 8 , the stent delivery system 200 may have a diameter of the stent 2 that is equal to or smaller than the diameter D of the proximal bond 16 when the balloon 1 is folded. Note that FIG. 8 shows a cross section similar to that of FIG. 2 . In this case, the diameter of the stent 2 is equal to or larger than the diameter of the inner tube 7.

[0141] It should be noted that the embodiments disclosed in this specification are merely examples, and the embodiments of the present disclosure are not limited to these, and can be modified as appropriate within the scope of the purpose of the present disclosure.

[0142] The present disclosure is applicable to stent delivery systems and methods of manufacturing the same.

[0143] DESCRIPTION OF SYMBOLS 1: Balloon 100: Balloon catheter 10: Straight portion 11: Wing base 12: Wing portion 12a: Inner portion 12b: Outer portion 13: Folded portion 14: Folded portion 16: Base-side joint portion (joint portion) 17: Distal-side joint portion 18: Base-side tapered portion 19: Distal-side tapered portion 2: Stent 200: Stent delivery system 21: Annular portion 22: Link portion 5: Shaft 51: Guidewire port 6: Outer tube 61: Lumen 7: Inner tube 71: Lumen 79: Distal tip 8: Hub 9: Crimp head 90: Hole portion C: Direction D: Diameter R: Direction Z: Direction

Claims

1. A stent delivery system comprising: a balloon catheter having a balloon that is inflated or deflated by the supply or discharge of a fluid; and a tubular stent that is placed on the balloon, the stent having the balloon inserted into the tube and fixed to the outer circumferential surface of the balloon, wherein the rate of change in diameter of the stent when a load of 5 N or more and 10 N or less is applied inward along the radial direction of the stent per 1 mm of length in the axial direction of the stent is 1.54% or less.

2. The stent delivery system according to claim 1, wherein the stent is formed from a metal alloy, and the metal alloy contains at least one selected from the group consisting of cobalt, chromium, nickel, tungsten, molybdenum, iron, and platinum as an alloy component.

3. The stent delivery system according to claim 2, wherein the stent is formed from L-605 alloy, which is an alloy containing cobalt, chromium, tungsten, and nickel.

4. A stent delivery system according to any one of claims 1 to 3, wherein the rate of change is 0.08% or more.

5. A stent delivery system according to any one of claims 1 to 4, wherein the rate of change is 1.44% or less.

6. A stent delivery system according to any one of claims 1 to 4, wherein the rate of change is 0.66% or less.

7. A stent delivery system according to any one of claims 1 to 4, wherein the rate of change is 0.60% or less.

8. A method for manufacturing a stent delivery system, comprising: a first diameter reduction step in which, with a balloon inserted into a tubular stent, the stent is compressed inward in the radial direction of the stent to reduce the diameters of the stent and the balloon, and then the compression is released; and a second diameter reduction step, which is carried out after the first diameter reduction step, the stent is compressed inward in the radial direction of the stent to reduce the diameters of the stent and the balloon, and then the compression is released, wherein the starting diameter of compression in the second diameter reduction step is smaller than the starting diameter of compression in the first diameter reduction step.

9. The method for manufacturing a stent delivery system according to claim 8, wherein the first diameter reduction step compresses the stent to a first diameter, and the second diameter reduction step compresses the stent to a second diameter, the second diameter being smaller than the first diameter.

10. A method for manufacturing a stent delivery system according to claim 8 or 9, wherein the second diameter reduction step is repeated two or more times.

11. A method for manufacturing a stent delivery system according to claim 10, wherein the second diameter in the second diameter reduction step is equal to or smaller than the second diameter in the second diameter reduction step carried out immediately before that step.

12. A method for manufacturing a stent delivery system described in any one of claims 8 to 10, wherein the compression in the second diameter reduction step is performed inward along the radial direction by applying a load of 5 N to 10 N per 1 mm of length in the axial direction of the stent.

13. A method for manufacturing a stent delivery system according to any one of claims 8 to 10, wherein in the second diameter reduction step, the stent is compressed until the diameter of the stent becomes 3.0 mm or less.

14. A method for manufacturing a stent delivery system as described in claim 10 or 11, wherein the repetition of the second diameter reduction step is terminated when the rate of change in diameter of the stent when a load of 5 N or more and 10 N or less is applied inward along the radial direction of the stent per 1 mm of length in the axial direction of the stent is 0.60% or less.

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