Stent delivery system and method for manufacturing stent delivery system

Abstract

A stent delivery system according to the present disclosure comprises a long shaft body, a balloon, and a tubular stent. The balloon in a contracted form comprises a blade part that includes an outer fold-back portion and is folded in the circumferential direction of the shaft body so as to follow along the shaft body. The stent comprises a plurality of annular parts each extending in a wavy line shape so as to repeat sparse sections and dense sections in the circumferential direction. The plurality of annular parts are connected along the longitudinal direction of the shaft body so as to form a sparse section region in which the sparse sections are arranged in a line along the longitudinal direction of the shaft body, and a dense section region in which the dense sections are arranged in a line along the longitudinal direction. The outer fold-back portion of the blade part of the balloon is covered by either the sparse section region or the dense section region of the stent.

Description

Stent Delivery System and Method for Manufacturing a Stent Delivery System

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

[0002] In recent years, for example, in the treatment of acute myocardial infarction, angina pectoris, etc., a method of implanting a stent in a stenotic portion of the coronary artery has been performed. Also, a similar method may be performed for improving stenotic portions formed in other blood vessels, bile ducts, tracheas, esophaguses, urethras, and other biological lumens. A stent delivery system used for implanting a stent usually includes a long shaft body, a balloon that covers the periphery of the outer side in the radial direction of the shaft body and is radially expandable, and a stent attached to the balloon. When the balloon expands at a target site in the living body, the stent attached to the balloon expands together with the balloon and expands the stenotic portion. Then, when the balloon is contracted, the stent is implanted in an expanded state, and the state of expanding the stenotic portion is maintained.

[0003] Patent Document 1 describes this type of stent delivery system. In the stent delivery system described in Patent Document 1, a groove corresponding to the shape of the stent or a cylindrical type is transferred to the balloon, and the stent is fitted into this groove.

[0004] Japanese Patent Application Laid-Open No. 2018-121944

[0005] In a stent delivery system, it is not preferable that there are individual differences in the holding force by which the balloon holds the stent. In a mass-produced stent delivery system, if there are individual differences in the above-mentioned holding force, for example, in a stent delivery system with a small holding force, the stent may accidentally fall off from the balloon. Also, for example, in a stent delivery system with a locally large holding force, a pinhole may occur in the balloon because only a part of the balloon is locally strongly pinched by the stent.

[0006] As described above, in the stent delivery system described in Patent Document 1, a groove corresponding to the shape of the stent or cylindrical object is transferred to the balloon, and the stent is fitted into this groove. Therefore, individual differences in the holding force are less likely to occur in the stent delivery system described in Patent Document 1. However, in the stent delivery system described in Patent Document 1, a step is required to form the groove for fitting the stent into the balloon in advance.

[0007] The present disclosure aims to provide a stent delivery system in which individual differences in the holding force of a balloon in holding a stent are less likely to occur, even if grooves for fitting the stent are not pre-formed in the balloon, and a method for manufacturing the stent delivery system.

[0008] A stent delivery system as a first aspect of the present disclosure comprises: (1) an elongated shaft body; a balloon covering the radially outer circumference of the shaft body and expanding radially outward from a contracted state folded circumferentially along the shaft body; and a cylindrical stent attached to the balloon in the contracted state and expanding radially outward together with the balloon when the balloon expands from the contracted state, wherein the balloon in the contracted state includes an outer folded portion that is convex radially outward and has wing portions folded circumferentially along the shaft body; the stent comprises a plurality of annular portions each extending in a wavy shape with alternating sparse and dense portions in the circumferential direction; the plurality of annular portions are connected along the longitudinal direction of the shaft body such that sparse regions are arranged in a line along the longitudinal direction of the shaft body and dense regions are arranged in a line along the longitudinal direction. The stent delivery system is such that the outer folded portion of the wing portion of the balloon is covered radially on its outer side by the sparse region or the dense region of the stent.

[0009] One embodiment of the stent delivery system of the present disclosure is the stent delivery system of (1) above, wherein the outer folded portion of the wing portion of the balloon is covered radially on the outside by the sparse region of the stent.

[0010] A stent delivery system as one embodiment of the present disclosure is the stent delivery system according to (1) or (2) above, wherein each of the plurality of annular portions comprises a first linear portion extending at an inclination with respect to the longitudinal direction and a second linear portion extending at an inclination angle smaller than that of the first linear portion with respect to the longitudinal direction, the sparse portion includes the first linear portion but does not include the second linear portion, and the dense portion includes the second linear portion but does not include the first linear portion.

[0011] A second aspect of the present disclosure is a method for manufacturing a stent delivery system: (4) A method for manufacturing a stent delivery system, the stent delivery system comprising: an elongated shaft body; a balloon that covers the radially outer circumference of the shaft body and is expandable radially outward from a contracted state that is folded circumferentially along the shaft body; and a cylindrical stent attached to the balloon in the contracted state, which is expandable radially outward together with the balloon when the balloon expands from the contracted state, wherein the balloon in the contracted state includes an outer folded portion that is convex radially outward and has wing portions that are folded circumferentially along the shaft body; and the stent comprises a plurality of annular portions, each extending in a wavy shape with alternating sparse and dense portions in the circumferential direction. A manufacturing method comprising a stent mounting step, in which the stent is attached to the contracted balloon such that the sparse portion or the dense portion covers the radially outer portion of the outer folded portion of the wing portion of the balloon.

[0012] According to this disclosure, it is possible to provide a stent delivery system in which individual differences in the holding force of the balloon in holding the stent are less likely to occur, even if grooves for fitting the stent are not pre-formed in the balloon, and a method for manufacturing the stent delivery system.

[0013] This figure shows a stent delivery system as one embodiment of the present disclosure. This is a cross-sectional view of the stent delivery system at the position of line I-I in Figure 1. This is an unfolded view of the stent shown in Figure 1. This is a flowchart of a method for manufacturing a stent delivery system as one embodiment of the present disclosure. This figure illustrates another stent delivery system to which the method for manufacturing a stent delivery system according to the present disclosure can be applied.

[0014] Hereinafter, embodiments of the stent delivery system and the method for manufacturing the stent delivery system according to this disclosure will be described with reference to the drawings. In each figure, identical components are denoted by the same reference numerals.

[0015] Figure 1 shows a stent delivery system 100 as one embodiment of the stent delivery system according to this disclosure.

[0016] As shown in Figure 1, the stent delivery system 100 comprises a long shaft body 10, a balloon 20, and a cylindrical stent 30. Hereinafter, in the stent delivery system 100, the longitudinal direction of the shaft body 10 will be simply referred to as "longitudinal direction A". Furthermore, in the stent delivery system 100, the tip side of longitudinal direction A that is inserted into the lumen will be referred to as "distal side A1", and the proximal side of longitudinal direction A that is manipulated by a user such as an operator outside the body will be referred to as "proximal side A2". In addition, in the stent delivery system 100, the circumferential direction of the shaft body 10, which is the direction around the shaft body 10 with the shaft body 10 as its central axis, will be simply referred to as "circumferential direction B". Furthermore, in the stent delivery system 100, the radial direction of the shaft body 10, which is the radial direction of a virtual circle with the shaft body 10 as its central axis in a cross-sectional view perpendicular to longitudinal direction A, will be simply referred to as "radial direction C".

[0017] The stent delivery system 100 is used to widen a narrowed or obstructed area in a blood vessel, bile duct, trachea, esophagus, urethra, or other biological lumen to secure the lumen.

[0018] The balloon 20 surrounds the outer circumference of the shaft body 10 in the radial direction C. The balloon 20 is expandable from a contracted state, folded in the circumferential direction B along the shaft body 10, outward in the radial direction C. Figure 1 shows the contracted state of the balloon 20.

[0019] The stent 30 is attached to the balloon 20 in its contracted state, and as the balloon 20 expands from its contracted state, the stent 30 can expand outward radially C along with the balloon 20. In other words, the stent 30 can also expand outward radially C from its contracted state, while attached to the balloon 20 in its contracted state. Figure 1 shows the contracted state of the stent 30.

[0020] Figure 2 is a cross-sectional view of the stent delivery system 100 at the position of line I-I in Figure 1. Figure 2 shows a cross-section of the retracted balloon 20 perpendicular to the longitudinal direction A. For convenience of explanation, the cross-sectional view of the stent delivery system 100 perpendicular to the longitudinal direction A shown in Figure 2 may be simply referred to as "cross-sectional view". As shown in Figure 2, the retracted balloon 20 includes an outer folded portion 22 that is convex outward in the radial direction C, and a wing portion 21 that is folded in the circumferential direction B along the shaft body 10.

[0021] Figure 3 is an unfolded view of the cylindrical stent 30, showing the stent 30 in an unfolded state. As shown in Figure 3, the stent 30 has a plurality of annular portions 31. Each of the plurality of annular portions 31 extends in a wavy line shape in the circumferential direction B, alternating between sparse portions 31a and dense portions 31b. Each of the plurality of annular portions 31 extends endlessly in the circumferential direction B. As shown in Figure 3, the plurality of annular portions 31 are connected along the longitudinal direction A such that sparse region 32a and dense region 32b are formed. The sparse region 32a is a region in the longitudinal direction A where the sparse portions 31a of the plurality of annular portions 31 are aligned in a line. The dense region 32b is a region in the longitudinal direction A where the dense portions 31b of the plurality of annular portions 31 are aligned in a line.

[0022] As shown in Figure 3, two adjacent annular portions 31 in the longitudinal direction A are connected in the longitudinal direction A by the connection of their close portions 31b, but the configuration is not limited to this. Two adjacent annular portions 31 in the longitudinal direction A may also be connected in the longitudinal direction A by the connection of their sparse portions 31a.

[0023] Figure 3 is an unfolded view of the stent 30 in its contracted state. Even when the stent 30 is expanded from its contracted state, each of the multiple annular portions 31 maintains a state in which sparse portions 31a and dense portions 31b alternate in a wavy pattern in the circumferential direction B. However, the sparse portions 31a and dense portions 31b in the stent 30 expanded from its contracted state are more elongated in the circumferential direction B than the sparse portions 31a and dense portions 31b in the stent 30 in its contracted state, and the length of the circumferential direction B becomes longer.

[0024] The deflated balloon 20 is covered radially C on its outer side by the deflated stent 30. In Figure 3, for the sake of explanation, the position of the outer folded portion 22 of the wing portion 21 of the deflated balloon 20, which is covered by the deflated stent 30, is shown by a dashed line. As shown in Figure 3, in this embodiment, the outer folded portion 22 of the wing portion 21 of the balloon 20 is covered radially C on its outer side by the sparse region 32a of the stent 30. In other words, the outer folded portion 22 of the balloon 20 in this embodiment is aligned with the sparse region 32a of the stent 30 in the circumferential direction B. Therefore, the outer folded portion 22 of the wing portion 21 of the balloon 20 in this embodiment is located within the range of the sparse region 32a of the stent 30 in the circumferential direction B. Furthermore, as shown in Figure 3, the outer folded portion 22 of the wing portion 21 of the balloon 20 is covered radially C on the outside by the sparse region 32a of the stent 30 over the entire length A of the stent 30.

[0025] In this embodiment, the outer folded portion 22 of the wing portion 21 of the balloon 20 is covered radially C on its outer side by the sparse region 32a of the stent 30, but the configuration is not limited to this. The outer folded portion 22 of the wing portion 21 of the balloon 20 may be covered radially C on its outer side by the dense region 32b of the stent 30. In other words, the outer folded portion 22 of the wing portion 21 of the balloon 20 may be covered radially C on its outer side by the dense region 32b of the stent 30 over the entire length A of the stent 30.

[0026] Furthermore, in this embodiment, when the retractable balloon 20 has multiple fin portions 21, it is sufficient that the outer folded portion 22 of at least one fin portion 21 is covered radially C on its outer side by a sparse region 32a or a dense region 32b of the stent 30. In Figures 2 and 3, the number of outer folded portions 22 covered by the sparse region 32a is less than the number of outer folded portions 22 covered by the dense region 32b. More specifically, Figures 2 and 3 show an example where only the outer folded portion 22a of one of the multiple fin portions 21 is covered radially C on its outer side by a sparse region 32a of the stent 30. In other words, in Figures 2 and 3, all other outer folded portions 22 (two outer folded portions 22 in Figures 2 and 3) are covered radially C on their outer sides by a dense region 32b of the stent 30.

[0027] However, the outer folded portion 22 of one of the multiple wing portions 21 may be covered radially C on its outer side by the dense region 32b of the stent 30, while all other outer folded portions 22 may be covered radially C on their outer side by the sparse region 32a. Alternatively, all outer folded portions 22 of the multiple wing portions 21 may be covered by separate sparse regions 32a of the stent 30. Alternatively, all outer folded portions 22 of the multiple wing portions 21 may be covered by separate dense regions 32b of the stent 30.

[0028] In this way, because the sparse region 32a or dense region 32b of the stent 30 is aligned in the circumferential direction B with the outer folded portion 22 of at least one fin portion 21 of the contracted balloon 20, even if a groove for fitting the stent 30 is not pre-formed in the balloon 20, individual differences in the holding force of the balloon 20 in holding the stent 30 are less likely to occur.

[0029] In particular, it is preferable that the outer folded portion 22 of at least one fin portion 21 of the balloon 20 is covered radially C on its outer side by a sparse region 32a of the stent 30. This makes it easier to see the outer folded portion 22 of the fin portion 21 from the outside radially C through the opening 71 of the stent 30, compared to a configuration in which the outer folded portion 22 of all fin portions 21 is covered radially C on its outer side by a dense region 32b of the stent 30. As a result, alignment of the balloon 20 and the stent 30 in the circumferential direction B becomes easier. Also, compared to a configuration in which the outer folded portion 22 of all fin portions 21 is covered radially C on its outer side by a dense region 32b of the stent 30, the overall maximum diameter of the balloon 20 and the stent 30 after the stent 30 is attached to the balloon 20 tends to be smaller.

[0030] Further details of the stent delivery system 100 of this embodiment will be described below.

[0031] As shown in Figure 1, the stent delivery system 100 of this embodiment includes, in addition to the shaft body 10, balloon 20, and stent 30 described above, a hub 40 fixed to the proximal end A2 of the shaft body 10.

[0032] The shaft body 10 of this embodiment comprises an outer tube 50 which is a tubular body, an inner tube 60 which is a tubular body disposed inside the outer tube 50, and a flexible distal end tip 64 connected to the distal end A1 of the inner tube 60. The outer tube 50 contains an expansion lumen 51 through which an expansion fluid for expanding the balloon 20 can flow. The inner tube 60 and the distal end tip 64 contain a guide wire lumen 61 through which a guide wire can be inserted. The expansion fluid may be a gas or a liquid, for example, helium gas, CO2.２ Gas, O ２ Examples include gases such as gases, and liquids such as physiological saline and contrast agents. By connecting the distal end tip 64 to the distal end A1 of the inner tube 60, the burden on the body caused by the distal end of the shaft body 10 contacting the inner wall of the biological lumen can be reduced. The inner tube 60 penetrates the inside of the balloon 20 in the longitudinal direction A. The guidewire lumen 61, which is partitioned inside the inner tube 60 and the distal end tip 64, opens to the outside at the distal opening 61a formed at the distal end of the distal end tip 64. The guidewire lumen 61 also opens to the outside at the proximal opening 61b formed at the proximal end A2 of the inner tube 60, which penetrates the side wall of the outer tube 50 and is liquid-tightly fixed to the outer tube 50 by adhesive or heat fusion. In other words, the guidewire lumen 61 extends from the distal opening 61a to the proximal opening 61b.

[0033] The hub 40 is fixed to the proximal end A2 of the outer tube 50. The hub 40 internally partitions a hub opening 41 that communicates with the expansion lumen 51 of the outer tube 50.

[0034] The constituent materials of the outer tube 50, inner tube 60, and distal end tip 64 preferably have a certain degree of flexibility. Examples of such materials include resin materials, such as polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or mixtures of two or more of these; thermoplastic resins such as soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, and fluororesin; silicone rubber and latex rubber.

[0035] Examples of materials used to construct the hub 40 include thermoplastic resins such as polycarbonate, polyamide, polysulfone, polyarylate, and methacrylate-butylene-styrene copolymer.

[0036] As shown in Figure 1, the balloon 20 of this embodiment includes an expandable body portion 25 that can be expanded and contracted in the radial direction C, a distal joint portion 26 connected to the distal side A1 of the expandable body portion 25 and joined to the outer surface of the inner tube 60 of the shaft body 10, and a proximal joint portion 27 connected to the proximal side A2 of the expandable body portion 25 and joined to the outer surface of the outer tube 50 of the shaft body 10. The expandable body portion 25 defines a fluid containment space between itself and the inner tube 60 on the inside in the radial direction C. The distal joint portion 26 is joined to the outer surface of the inner tube 60 by means of, for example, adhesive, heat fusion, etc. The proximal joint portion 27 is joined to the outer surface of the outer tube 50 by means of, for example, adhesive, heat fusion, etc. The expandable body portion 25 also includes a substantially cylindrical tubular portion 25a located in the center of the longitudinal direction A. In the expanded form of the balloon 20, the tubular portion 25a has a uniform outer diameter regardless of its position in the longitudinal direction A. However, the outer shape of the cylindrical portion 25a in the expanded balloon 20 in a cross-sectional view perpendicular to the longitudinal direction A is not limited to a circular shape, and may have other outer shapes such as an oval shape. Furthermore, the expanded body portion 25 of this embodiment is connected to the distal side A1 of the cylindrical portion 25a and includes a distal tapered portion 25b in the expanded balloon 20 whose outer diameter decreases towards the distal side A1. Moreover, the expanded body portion 25 of this embodiment is connected to the proximal side A2 of the cylindrical portion 25a and includes a proximal tapered portion 25c in the expanded balloon 20 whose outer diameter decreases towards the proximal side A2.

[0037] The fluid-containing space inside the balloon 20 is in communication with an expansion lumen 51 formed in the outer tube 50. Expansion fluid can flow into the fluid-containing space inside the balloon 20 from the proximal side A2 via the expansion lumen 51. The balloon 20 expands upon the inflow of expansion fluid into the fluid-containing space. Conversely, the balloon 20 folds and contracts upon the outflow of expansion fluid from the fluid-containing space.

[0038] As shown in Figure 2, the contracted balloon 20 is shaped to fold so as to wrap around the outer surface of the inner tube 60 of the shaft body 10 in the circumferential direction B.

[0039] Specifically, the retractable balloon 20, in cross-sectional view (see Figure 2), has fin portions 21 that protrude radially outward from the outer circumferential surface of the inner tube 60, which serves as the outer surface of the shaft body 10, in the radial direction C. The retractable balloon 20 of this embodiment has a plurality of fin portions 21 that are spaced apart in the circumferential direction B. Each of the plurality of fin portions 21 forms a peak portion as a ridge portion by an outer folded portion 22 that is convex outward in the radial direction C. Two adjacent fin portions 21 in the circumferential direction B are in contact with or close to the outer circumferential surface of the inner tube 60 and are connected by an inner folded portion 23 that is convex inward in the radial direction C. In other words, the inner folded portion 23 is a valley portion between two adjacent fin portions 21 in the circumferential direction B, which is concave outward in the radial direction C. As shown in Figure 2, in the retractable balloon 20, the plurality of fin portions 21 are wrapped around the outer circumferential surface of the inner tube 60 in the circumferential direction B so as to follow the outer circumferential surface of the inner tube 60. In this way, the contracted balloon 20 is folded so that multiple fin portions 21 are wrapped around the outer surface of the inner tube 60.

[0040] As shown by the dashed line in Figure 3, the outer folded portion 22 of the wing portion 21 extends linearly in a direction approximately parallel to the longitudinal direction A, at a position where the outer side in the radial direction C is covered by the stent 30.

[0041] As shown in Figure 2, the deflated balloon 20 of this embodiment has three fin portions 21, but the number of fin portions 21 is not particularly limited. The number of fin portions 21 may be two or less, or four or more.

[0042] Although details will be described later, the stent 30 is attached to the balloon 20 so as to cover the outside in the radial direction C of the balloon 20 in a contracted form that is folded along the outer surface of the shaft body 10. More specifically, the linear struts 70 constituting the stent 30 are in close contact with the balloon 20 in the contracted form so as to push the balloon 20 in the contracted form inward in the radial direction C. Therefore, the balloon 20 enters the opening 71 formed by the linear struts 70 around the position where it is pushed inward in the radial direction C by the struts 70. Thus, the stent 30 is attached to the balloon 20 in the contracted form by caulking (crimping) the struts 70 constituting the stent 30 against the balloon 20 in the contracted form.

[0043] The folded shape of the balloon 20 in the above-described contracted form may be shaped, for example, by blow molding in which the parison portion of the tube serving as the material is heated in a mold, inflated with a gas such as nitrogen from the inside, pressurized, and pressed against the mold.

[0044] The balloon 20 is preferably formed of a material having a certain degree of flexibility. Examples of such materials include engineering plastics, such as polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of two or more of these, soft polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, thermoplastic resins such as fluororesin, silicone rubber, latex rubber, and the like.

[0045] The stent 30 is a so-called balloon-expandable stent that plastically deforms and expands by the expanding force of the balloon 20. The stent 30 is supported on the outer surface of the cylindrical portion 25a of the expanding main body portion 25 of the balloon 20. As the material for forming the stent 30, a synthetic resin or a metal is used. As the synthetic resin, a synthetic resin having a certain degree of hardness and elasticity is mentioned, and a biocompatible synthetic resin is preferred. Specifically, the synthetic resin is a polyolefin (for example, polyethylene, polypropylene), a polyester (for example, polyethylene terephthalate), a fluororesin (for example, PTFE, ETFE), or a polylactic acid, a polyglycolic acid, or a copolymer of polylactic acid and polyglycolic acid, which is a biodegradable material.

[0046] As the metal used for the material of the stent 30, a metal having biocompatibility is preferred. For example, stainless steel, tantalum or a tantalum alloy, platinum or a platinum alloy, gold or a gold alloy, a cobalt-based alloy such as a cobalt-chromium alloy, a nickel-titanium alloy, etc. are mentioned. Further, after the shape of the stent 30 is produced, noble metal plating (gold, platinum) may be applied.

[0047] The stent 30 may be, for example, a drug-eluting stent provided with a drug layer eluted in vivo. However, the stent 30 is not limited to a drug-eluting stent.

[0048] The stent 30 is cylindrical and reticulated. Specifically, the stent 30 is composed of linear struts 70. The struts 70 form a reticulated peripheral wall in which openings 71 are formed. When the balloon 20 expands, the stent 30 can be deformed so that the openings 71 between the struts 70 expand and the diameter can be increased.

[0049] As shown in Figure 3, the stent 30 comprises a plurality of annular portions 31 that extend in a wavy shape in the circumferential direction B, each alternating between sparse portions 31a and dense portions 31b. Each annular portion 31 is formed by a linear strut 70. Each annular portion 31 comprises a distal bent portion 33 that is convex toward the distal side A1 in the longitudinal direction A, a proximal bent portion 34 that is convex toward the proximal side A2 in the longitudinal direction A, and a linear portion 35 that connects the distal bent portion 33 and the proximal bent portion 34. The distal bent portion 33 and the proximal bent portion 34 deform to expand in the circumferential direction B when the stent 30 expands in the radial direction C. In this embodiment, each annular portion 31 comprises a plurality of distal bent portions 33, a plurality of proximal bent portions 34, and a plurality of linear portions 35. The distal bend portion 33 and the proximal bend portion 34 are formed alternately along the wavy extension direction D of the strut 70 that forms each annular portion 31.

[0050] As shown in Figure 3, each of the multiple linear portions 35 of the multiple annular portions 31 in this embodiment includes a plurality of first linear portions 35a and a plurality of second linear portions 35b. The first linear portions 35a extend inclined with respect to the longitudinal direction A. The second linear portions 35b extend substantially parallel to the longitudinal direction A. More specifically, the plurality of linear portions 35 in this embodiment are composed of a plurality of first linear portions 35a and a plurality of second linear portions 35b.

[0051] As shown in Figure 3, in this embodiment, each of the multiple annular portions 31 has a sparse portion 31a which does not include a second linear portion 35b but includes a first linear portion 35a. Also, each of the multiple annular portions 31 has a dense portion 31b which does not include a first linear portion 35a but includes a second linear portion 35b. More specifically, each annular portion 31 in this embodiment is composed of multiple sparse portions 31a and multiple dense portions 31b. Each of the sparse portions 31a in each annular portion 31 in this embodiment does not include a second linear portion 35b but includes only one first linear portion 35a. Also, each of the dense portions 31b in each annular portion 31 in this embodiment does not include a first linear portion 35a but includes four second linear portions 35b.

[0052] However, the number of first linear portions 35a included in each sparse portion 31a is not particularly limited. Each sparse portion 31a may contain two or more first linear portions 35a. Also, the number of second linear portions 35b included in each dense portion 31b is not particularly limited. Each dense portion 31b may contain, for example, only one second linear portion 35b. Furthermore, each dense portion 31b may contain, for example, two or three second linear portions 35b. Moreover, each dense portion 31b may contain, for example, five or more second linear portions 35b.

[0053] Furthermore, although the second linear portion 35b in this embodiment is configured to extend substantially parallel to the longitudinal direction A, the second linear portion 35b may also be configured to extend at a smaller inclination angle with respect to the longitudinal direction A than the first linear portion 35a. In addition, each annular portion 31 may include, for example, both a second linear portion 35b that extends substantially parallel to the longitudinal direction A and a second linear portion 35b that extends at a smaller inclination angle with respect to the longitudinal direction A than the first linear portion 35a.

[0054] Furthermore, the sparse portion 31a of each annular portion 31 in this embodiment includes the portion of each annular portion 31 where the separation distance L is maximum. As shown in Figure 3, the separation distance L is the distance in the circumferential direction E of each annular portion 31 between one distal bend portion 33 and one proximal bend portion 34, which are connected by one linear portion 35. In this embodiment, the circumferential direction E of each annular portion 31 is the same direction as the circumferential direction B. In each annular portion 31 in this embodiment, the separation distance L is maximum at the position of the first linear portion 35a. In other words, the sparse portion 31a of each annular portion 31 in this embodiment is composed of the portion of each annular portion 31 where the separation distance L is maximum. Furthermore, the dense portion 31b of each annular portion 31 in this embodiment is composed of the portion of each annular portion 31 other than the sparse portion 31a. As shown in Figure 3, in the dense portion 31b of each annular portion 31 in this embodiment, the separation distance L is almost zero.

[0055] Furthermore, in each annular portion 31 of this embodiment, the sparse portion 31a and the dense portion 31b have different volume densities, which are the ratio of the volume of the strut 70 to the volume of a unit volume. The volume density of the sparse portion 31a is smaller than that of the dense portion 31b. The "unit volume" may be set to include at least one distal bend portion 33 and at least one proximal bend portion 34.

[0056] As shown in Figure 3, the multiple annular portions 31 are arranged in a line along the longitudinal direction A. The multiple annular portions 31 arranged along the longitudinal direction A form a sparse region 32a where the sparse portions 31a are lined up in a row along the longitudinal direction A. The multiple annular portions 31 arranged along the longitudinal direction A also form a dense region 32b where the dense portions 31b are lined up in a row along the longitudinal direction A. The stent 30 of this embodiment comprises multiple sparse regions 32a and multiple dense regions 32b. Each sparse region 32a of this embodiment extends over the entire area of ​​the stent 30 in the longitudinal direction A. Each dense region 32b of this embodiment extends over the entire area of ​​the stent 30 in the longitudinal direction A. The sparse regions 32a and dense regions 32b are arranged alternately in the circumferential direction B. Two adjacent annular portions 31 in the longitudinal direction A are connected by a connecting portion 36. In this embodiment, the connecting portion 36 connects the close portions 31b of two adjacent annular portions 31 in the longitudinal direction A. More specifically, the connecting portion 36 in this embodiment connects the distal bent portion 33 of the close portion 31b of one of the two adjacent annular portions 31 and the proximal bent portion 34 of the close portion 31b of the other of the two adjacent annular portions 31.

[0057] In this way, multiple annular portions 31 are arranged along the longitudinal direction A, and two annular portions 31 adjacent to each other in the longitudinal direction A are connected, so that the stent 30 has a cylindrical and mesh-like shape with multiple openings 71 formed therein.

[0058] Next, referring to Figure 3, the positional relationship between the outer folded portion 22 of the wing portion 21 of the contracted balloon 20 and the sparse region 32a and dense region 32b of the stent 30 will be explained.

[0059] As shown in Figure 3, the outer folded portion 22 of the fin portion 21 of the deflated balloon 20 is covered radially C on its outer side by the sparse region 32a of the stent 30. The deflated balloon 20 of this embodiment has a plurality of fin portions 21, as described above. The outer folded portion 22 of at least one of the plurality of fin portions 21 (only one fin portion 21 in this embodiment) is covered radially C on its outer side by the sparse region 32a of the stent 30. More specifically, the outer folded portion 22 of at least one of the plurality of fin portions 21 (only one fin portion 21 in this embodiment) is covered radially C on its outer side by the sparse region 32a over the entire area in the longitudinal direction A where the stent 30 covers the radially C outer side. In other words, the stent 30 is attached to the radially C outside of the contracted balloon 20, with the sparse region 32a aligned in the circumferential direction B with the outer folded portion 22 of at least one wing portion 21.

[0060] As described above, the outer folded portion 22 of the wing portion 21 of the contracted balloon 20 may be covered radially C on its outer side by the dense region 32b of the stent 30.

[0061] In this way, because the sparse region 32a or dense region 32b of the stent 30 is aligned in the circumferential direction B with the outer folded portion 22 of at least one fin portion 21 of the contracted balloon 20, even if a groove for fitting the stent 30 is not pre-formed in the balloon 20, individual differences in the holding force of the balloon 20 in holding the stent 30 can be suppressed.

[0062] Furthermore, as described above, it is preferable that the outer folded portion 22 of at least one fin portion 21 of the balloon 20 is covered radially C on its outer side by the sparse region 32a of the stent 30, as in this embodiment. By doing so, compared to a configuration in which the outer folded portions 22 of all fin portions 21 are covered radially C on their outer sides by the dense region 32b of the stent 30, the outer folded portions 22 of the fin portions 21 are easier to see from the radially C on their outer side through the opening 71 of the stent 30. As a result, alignment of the balloon 20 and the stent 30 in the circumferential direction B becomes easier. In addition, the area near the outer folded portion 22 of the fin portion 21 is more flexible and easily deformable compared to the area near the outer folded portion 22 of the fin portion 21, and is easier to insert into the opening 71 of the stent 30. Therefore, by configuring the outer folded portion 22 of at least one wing portion 21 to be covered radially C on its outer side by the sparse region 32a of the stent 30, the overall maximum diameter of the balloon 20 and stent 30 after the stent 30 is attached to the balloon 20 tends to be smaller compared to a configuration in which the outer folded portions 22 of all wing portions 21 are covered radially C on their outer side by the dense region 32b of the stent 30. In other words, the overall diameter of the balloon 20 and stent 30 when the stent 30 is attached to the balloon 20 tends to be reduced.

[0063] As shown in Figure 2, the stent 30 is attached to the contracted balloon 20 in a state where the linear struts 70 constituting the stent 30 are deformed by pushing the surface of the contracted balloon 20 located on the outside in the radial direction C inward. The portion of the contracted balloon 20 that is not pushed inward in the radial direction C by the struts 70 is inserted into the opening 71 of the stent 30. By attaching the stent 30 to the contracted balloon 20 in this way, so that a portion of the contracted balloon 20 is inserted into the opening 71 of the stent 30, the holding force of the stent 30 by the balloon 20 can be increased. Furthermore, as described above, by aligning the sparse region 32a or dense region 32b of the stent 30 with the outer folded portion 22 of at least one wing portion 21 of the contracted balloon 20 in the circumferential direction B, individual differences in the holding force can be suppressed.

[0064] Next, with reference to Figure 4, an example of a manufacturing method for the stent delivery system 100 described above will be explained. The manufacturing method shown in Figure 4 includes a balloon folding step S1 in which the balloon 20 is folded so as to wrap around the shaft body 10, thereby making the balloon 20 into a contracted form, and a stent mounting step S2 in which the stent 30 is attached to the contracted balloon 20 such that the sparse portion 31a of the annular portion 31 of the stent 30 covers the radially outer side C of the outer folded portion 22 of the wing portion 21 of the contracted balloon 20.

[0065] In the stent installation process S2, first, the stent 30 is positioned on the outside of the balloon 20 in its contracted state, radially C in such a way that the sparse portion 31a of the annular portion 31 of the stent 30 covers the outside of the outer folded portion 22 of the wing portion 21 of the balloon 20 in its contracted state. In this state, the stent 30 is compressed inward in the radial direction C, and the stent 30 is attached to the balloon 20 in its contracted state (see Figure 2).

[0066] As described above, in the contracted balloon 20 of the stent delivery system 100, as shown by the dashed line in Figure 3, the outer folded portion 22 of the wing portion 21 extends linearly in a manner substantially parallel to the longitudinal direction A at a position where the outer side in the radial direction C is covered by the stent 30. Therefore, in the stent installation process S2, any one of the multiple annular portions 31 arranged in line in the longitudinal direction A can be used to align the sparse portion 31a with the outer folded portion 22 of the wing portion 21 of the balloon 20 in the circumferential direction B. In this way, the outer folded portion 22 of the balloon 20 can be configured so that the outer side in the radial direction C is covered by the sparse region 32a over the entire area in the longitudinal direction A where the outer side in the radial direction C is covered by the stent 30.

[0067] Here, in the stent mounting process S2, an example is shown in which the sparse portion 31a of the annular portion 31 of the stent 30 is aligned with the outer folded portion 22 of the wing portion 21, but the configuration is not limited to this. In the stent mounting process S2, the dense portion 31b of the annular portion 31 of the stent 30 may be aligned with the outer folded portion 22 of the wing portion 21. This makes it possible to achieve a configuration in which the outer folded portion 22 of the balloon 20 is covered by the dense portion region 32b over the entire area in the longitudinal direction A where the outer side in the radial direction C is covered by the stent 30.

[0068] However, as shown in Figure 5, there exists a stent delivery system 200 that includes a retractable balloon 220 in which the outer folded portion 222 of the wing portion 221 does not extend linearly parallel to the longitudinal direction A, but rather extends spirally so that its position in the circumferential direction B gradually changes depending on its position in the longitudinal direction A. Figure 5 shows an unfolded view of the stent 30 of the stent delivery system 200, and the position of the outer folded portion 222 of the wing portion 221 of the retractable balloon 220 is indicated by a dashed line. Even with such a stent delivery system 200, by using the manufacturing method shown in Figure 4, it is possible to suppress individual differences in the holding force of the stent 30 by the balloon 220. In other words, in the stent installation process S2, one annular portion 31 located at a predetermined position in the longitudinal direction A, among a plurality of annular portions 31 arranged in line in the longitudinal direction A, can be used to align the sparse portion 31a with the outer folded portion 222 of the wing portion 221 of the balloon 220 in the circumferential direction B. The one annular portion 31 located at a predetermined position in the longitudinal direction A may be an annular portion 31 located at any position in the longitudinal direction A, provided it is predetermined. Specifically, the one annular portion 31 located at a predetermined position in the longitudinal direction A may be, for example, an annular portion 31 located at the distal end A1 in the longitudinal direction A. Also, the one annular portion 31 located at a predetermined position in the longitudinal direction A may be, for example, an annular portion 31 located at the proximal end A2 in the longitudinal direction A. Furthermore, the one annular portion 31 located at a predetermined position in the longitudinal direction A may be, for example, an annular portion 31 located in the center of the longitudinal direction A. In this way, the one annular portion 31 located at a predetermined position in the longitudinal direction A is always used for aligning the sparse portion 31a and the outer folded portion 222 of the wing portion 221 of the balloon 220 in the circumferential direction B. Therefore, it is possible to suppress individual differences in the retention force of the stent 30 by the balloon 220 in the manufactured stent delivery system.

[0069] As described above, the method for manufacturing a stent delivery system according to this disclosure is not limited to a stent delivery system 100 (see Figures 1 to 3) that includes a retractable balloon 20 in which the outer folded portion 22 of the wing portion 21 extends linearly substantially parallel to the longitudinal direction A, but is also applicable to a stent delivery system 200 (see Figure 5) that includes a retractable balloon 220 in which the outer folded portion 222 of the wing portion 221 does not extend linearly substantially parallel to the longitudinal direction A, but extends spirally so that the position in the circumferential direction B gradually changes depending on the position in the longitudinal direction A.

[0070] The stent delivery system and the method for manufacturing the stent delivery system relating to this disclosure are not limited to the specific configurations and processes shown in the embodiments described above, and various modifications, substitutions, and combinations are possible without departing from the scope of the claims.

[0071] This disclosure relates to a stent delivery system and a method for manufacturing a stent delivery system.

[0072] 10: Shaft body 20, 220: Balloon 21, 221: Wing section 22, 22a, 222: Outer folded section 23: Inner folded section 25: Expansion main body section 25a: Cylindrical section 25b: Distal tapered section 25c: Proximal tapered section 26: Distal joint section 27: Proximal joint section 30: Stent 31: Annular section 31a: Sparse section 31b: Dense section 32a: Sparse area 32b: Dense area 33: Distal bend section 34: Proximal bend section 35: Linear section 35a: First linear section 35b: Second linear section 36: Connecting section 40: Hub 41: Hub opening 50: Outer tube 51: Expansion lumen 60: Inner tube 61: Guide wire lumen 61a: Distal opening 61b: Proximal opening 64: Distal end tip 70: Strut 71: Opening 100, 200: Stent entry / exit barrier system A: Longitudinal direction A1: Distal side A2: Proximal side B: Circumferential direction C: Radial direction D: Extending direction of the annular portion E: Circumferential direction of the annular portion L: Separation distance

Claims

1. The device comprises: an elongated shaft body; a balloon covering the radially outer circumference of the shaft body and expanding radially outward from a contracted state folded circumferentially along the shaft body; and a cylindrical stent attached to the balloon in its contracted state, which expands radially outward together with the balloon when the balloon expands from its contracted state, wherein the balloon in its contracted state includes an outer folded portion that is convex radially outward and has wing portions that are folded circumferentially along the shaft body; the stent comprises a plurality of annular portions each extending in a wavy shape with alternating sparse and dense portions in the circumferential direction; the plurality of annular portions are connected along the longitudinal direction of the shaft body such that sparse regions are formed where the sparse portions are aligned in a row along the longitudinal direction, and dense regions are formed where the dense portions are aligned in a row along the longitudinal direction. A stent delivery system in which the outer folded portion of the wing portion of the balloon is covered radially on its outer side by the sparse region or the dense region of the stent.

2. The stent delivery system according to claim 1, wherein the outer folded portion of the wing portion of the balloon is covered radially on the outside by the sparse region of the stent.

3. The stent delivery system according to claim 1 or 2, wherein each of the plurality of annular portions comprises a first linear portion extending inclined with respect to the longitudinal direction and a second linear portion extending inclined with respect to the longitudinal direction at a smaller angle of inclination than the first linear portion, or substantially parallel to the longitudinal direction, the sparse portion includes the first linear portion but does not include the second linear portion, and the dense portion includes the second linear portion but does not include the first linear portion.

4. A method for manufacturing a stent delivery system, the stent delivery system comprising: an elongated shaft body; a balloon that covers the radially outer circumference of the shaft body and is expandable radially outward from a contracted state that is folded circumferentially along the shaft body; a cylindrical stent attached to the balloon in the contracted state and expandable radially outward together with the balloon when the balloon expands from the contracted state; the balloon in the contracted state includes an outer folded portion that is convex radially outward and has a wing portion that is folded circumferentially along the shaft body; the stent comprises a plurality of annular portions, each extending in a wavy shape with alternating sparse and dense portions in the circumferential direction; and a method for manufacturing the stent comprising a stent attachment step of attaching the stent to the balloon in the contracted state such that the sparse portion or the dense portion covers the radially outer side of the outer folded portion of the wing portion of the balloon.

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