Balloon for balloon catheter and balloon catheter

Abstract

This balloon (10) for a balloon catheter has: a wire (17) disposed on the outer surface of a balloon body part (16); and a drug layer (22) provided on both the surface of the wire (17) and the outer surface of the balloon body part (16). In a cross section of the balloon (10), the maximum thickness T1 of the drug layer (22) in a specific region (19) is greater than the maximum thickness T2 of the drug layer (22) on the outer surface of the balloon body part (16) outside the specific region (19), wherein the specific region (19) is surrounded by a specific shape (18) obtained by expanding the cross-sectional outer edge of the wire (17) by a factor of two around the centroid (17C) of the cross-sectional outer edge of the wire (17).

Description

Balloon for balloon catheter and balloon catheter

[0001] The present invention relates to a balloon for a balloon catheter having a drug retained on its surface, and a balloon catheter equipped with the balloon.

[0002] It is known that stenosis in blood vessels, which are the channels through which blood circulates in the body, can lead to various diseases due to stagnation of blood circulation. In particular, stenosis in the coronary arteries that supply blood to the heart can lead to serious diseases such as angina pectoris and myocardial infarction. One method for treating such vascular stenosis is angioplasty (PTA, PTCA, etc.), which dilates the stenotic area using a balloon catheter.

[0003] Known balloon catheters include those with a wire on the surface of the balloon that holds a drug (see, for example, Patent Documents 1 to 3). When such a balloon catheter is used, the wire on the surface of the balloon penetrates the narrowed area when the balloon is inflated, effectively widening the narrowed area and transferring the drug to the inner wall of a body cavity, such as a blood vessel wall, which is expected to prevent restenosis and other conditions from occurring.

[0004] Special table 2008-539959 Publication Special table 2015-505497 Publication Special table 2021-521971

[0005] It is desirable that a balloon catheter with a drug retained on the surface of the balloon be able to efficiently deliver the drug to the inner wall of a body cavity such as a blood vessel by expanding the balloon at a stenosis or lesion in the body cavity such as a blood vessel. The present invention has been made in view of the above circumstances, and its object is to provide a balloon for a balloon catheter that can efficiently deliver a drug to the inner wall of a body cavity such as a blood vessel, and a balloon catheter equipped with the balloon.

[0006] The balloon for a balloon catheter and the balloon catheter equipped with the balloon of the present invention, which have been able to solve the above-mentioned problems, are as follows. [1] A balloon for a balloon catheter having a longitudinal axis direction extending from a proximal side to a distal side and radial and circumferential directions perpendicular to the longitudinal axis direction, wherein the balloon has a balloon main body and a wire rod arranged radially outward from the balloon main body, and has a straight tube section, a proximal tapered section located proximal to the straight tube section, and a distal tapered section located distal to the straight tube section, wherein the wire rod extends parallel to the longitudinal axis direction or obliquely at an angle of 45° or less with respect to the longitudinal axis direction in the straight tube section, and a drug layer is provided from the surface of the wire rod to the outer surface of the balloon main body, and the maximum thickness of the drug layer in a region (hereinafter referred to as the "specific region") surrounded by a specific shape obtained by enlarging the outer edge of the cross section of the wire rod by two times, centered on the centroid of the outer edge of the cross section of the wire rod, in a vertical cross section in the longitudinal axis direction of the straight tube section is thicker than the maximum thickness of the drug layer on the outer surface of the balloon main body outside the specific region. [2] A balloon for a balloon catheter having a longitudinal axis direction extending from a proximal side to a distal side and radial and circumferential directions perpendicular to the longitudinal axis direction, wherein the balloon has a balloon main body and a wire rod arranged radially outward from the balloon main body, and has a straight tube section, a proximal tapered section located proximal to the straight tube section, and a distal tapered section located distal to the straight tube section, wherein the wire rod extends parallel to the circumferential direction or obliquely at an angle of more than 45° with respect to the longitudinal axis direction in the straight tube section, and a drug layer is provided from the surface of the wire rod to the outer surface of the balloon main body, and in a cross section of the straight tube section taken along the longitudinal axis direction and the radial direction, the maximum thickness of the drug layer within a region (hereinafter referred to as a "specific region") surrounded by a specific shape obtained by enlarging the outer edge of the cross section of the wire rod by two times, with the centroid of the outer edge of the cross section of the wire rod as the center, is thicker than the maximum thickness of the drug layer on the outer surface of the balloon main body outside the specific region.[3] The balloon according to [1], wherein, in a cross section perpendicular to the longitudinal axis direction of the straight tubular portion, the maximum thickness of the drug layer in the radially inner half of the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region. [4] The balloon according to [2], wherein, in a cross section along the longitudinal axis direction and the radial direction of the straight tubular portion, the maximum thickness of the drug layer in the radially inner half of the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region. [5] The balloon according to [1] or [3], wherein, in a cross section perpendicular to the longitudinal axis direction of the straight tubular portion, the maximum thickness of the drug layer on the outer surface of the balloon main body portion other than the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region. [6] The balloon according to [2] or [4], wherein, in a cross section of the straight tube portion taken along the longitudinal axis direction and the radial direction, the maximum thickness of the drug layer on the outer surface of the balloon main body outside the specific region is greater than the maximum thickness of the drug layer on the radially outer half of the specific region. [7] The balloon according to [1], [3], or [5], wherein, in a cross section perpendicular to the longitudinal axis direction of the straight tube portion, the drug layer is present between the outer surface of the balloon main body and the outer edge of the cross section of the wire rod facing the outer surface of the balloon main body. [8] The balloon according to [2], [4], or [6], wherein, in a cross section of the straight tube portion taken along the longitudinal axis direction and the radial direction, the drug layer is present between the outer surface of the balloon main body and the outer edge of the cross section of the wire rod facing the outer surface of the balloon main body. [9] The balloon according to [7] or [8], wherein a gap without the drug layer is present between the outer edge of the cross section of the wire rod facing the outer surface of the balloon main body and the outer surface of the balloon main body.

[10] The balloon according to any one of [1] to [9], wherein a crack extending along the extending direction of the wire is formed on the surface of the drug layer.

[11] The balloon according to

[10] , wherein a protective layer is provided on the outer surface of the drug layer, and the protective layer covers at least a part of the crack.

[12] The balloon according to any one of [1] to

[11] , wherein, in a cross section perpendicular to the direction of extension of the wire, the widthwise length of the outer half of the wire in the radial direction is at least twice the length of the wire in the radial direction.

[13] The balloon according to any one of [1] to

[12] , wherein the balloon has a proximal sleeve section located proximal to the proximal tapered section and a distal sleeve section located distal to the distal tapered section, and the proximal end of the wire is fixed to the proximal sleeve section and / or the proximal tapered section, and the distal end of the wire is fixed to the distal sleeve section and / or the distal tapered section.

[14] The balloon according to any one of [1] to

[13] , wherein the wire is made of resin, metal, or a combination thereof.

[15] The balloon according to any one of [1] to

[14] , wherein the surface free energy of the material constituting the surface of the wire is different from the surface free energy of the material constituting the outer surface of the balloon body.

[16] The balloon according to any one of [1] to

[14] , wherein the surface free energy of the material constituting the surface of the wire is greater than the surface free energy of the material constituting the outer surface of the balloon body.

[17] The balloon according to any one of [1] to

[16] , wherein, in the deflated state of the balloon, the balloon has folding wings formed by folding the balloon body with the inner surface facing inward, the folding wings being positioned on the outer surface of the balloon and covering the wire.

[18] The balloon according to any one of [1] to

[16] , wherein, in the deflated state of the balloon, the balloon has folding wings formed by folding the balloon body with the inner surface facing inward, the folding wings being positioned on the outer surface of the balloon, the wire being positioned on the radially outer side of the folding wings.

[19] A balloon catheter comprising the balloon according to any one of [1] to

[18] .

[0007] The balloon for balloon catheter of the present invention allows efficient transfer of a drug to the inner surface of a blood vessel wall or the like when the balloon is inflated at a stenosis or lesion in a blood vessel or the like. For example, when the balloon is inflated at a stenosis in a blood vessel, the wires arranged on the balloon surface penetrate the stenosis, effectively dilating the stenosis. Furthermore, the thick drug layer around the wires allows efficient transfer of a drug from the inner surface of the blood vessel wall to the interior of the stenosis at the dilated stenosis. Alternatively, the wires arranged on the balloon surface function to partially suppress balloon expansion, effectively rupturing the thicker drug layer around the wires when the balloon is inflated, facilitating the drug layer peeling off from the balloon. This allows efficient transfer of a drug to the inner wall of a body cavity, such as a blood vessel.

[0008] 1 shows an example of a configuration of a balloon catheter according to an embodiment of the present invention, and is a side view of the balloon catheter excluding the drug layer on the balloon surface.

[0034] FIG. 1 shows an end view of the balloon catheter shown in FIG. 1 cut along line II-II.

[0035] FIG. 1 shows an end view of the balloon catheter shown in FIG. 1 cut along line III-III.

[0036] FIG. 1 shows a perspective view of a balloon included in the balloon catheter shown in FIG. 1.

[0037] FIG. 4 shows a vertical cross-sectional view of the balloon in the longitudinal axis direction, showing a cross-sectional view of a balloon with a drug layer provided on its surface.

[0038] FIG. 5 shows an enlarged cross-sectional view of the wire of the balloon shown in FIG. 5.

[0039] FIG. 7 shows a cross-sectional view of a balloon in the longitudinal axis direction and radial direction, showing a cross-sectional view of a balloon with a drug layer provided on its surface.

[0039] FIG. 8 shows an enlarged cross-sectional view of the wire of the balloon shown in FIG. 6 shows an example of a configuration of a balloon with cracks formed in the surface of the drug layer.

[0039] FIG. 10 shows a cross-sectional view of the wire of the balloon shown in FIG. 10 shows an example of a configuration of a balloon with a protective layer provided on the outer surface of the drug layer to cover the cracks. 1 shows examples of cross-sectional configurations of various wire rods, each showing a vertical cross-section in the extension direction of the wire rod; 2 shows an example of a folded state of a balloon, showing a vertical cross-section in the longitudinal axis direction of the folded balloon; 3 shows another example of a folded state of a balloon, showing a vertical cross-section in the longitudinal axis direction of the folded balloon; 4 shows another example of a folded state of a balloon, showing a vertical cross-section in the longitudinal axis direction of the folded balloon.

[0009] The present invention will be described in detail below based on the following embodiments. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience. In such cases, reference should be made to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping understand the features of the present invention.

[0010] A balloon for a balloon catheter according to an embodiment of the present invention and an example of a configuration of a balloon catheter equipped with the balloon will be described with reference to the drawings. Figures 1 to 4 and 7 show an example of a configuration of a balloon catheter without the drug layer of the balloon. Figure 1 shows a side view of the balloon catheter, Figure 2 shows an end view of the balloon catheter shown in Figure 1 cut along line II-II, Figure 3 shows an end view of the balloon catheter shown in Figure 1 cut along line III-III, Figure 4 shows a perspective view of the balloon equipped in the balloon catheter shown in Figure 1, and Figure 7 shows a perspective view of another example of a balloon equipped in a balloon catheter. Figure 1 shows an example of a configuration of a rapid exchange type balloon catheter.

[0011] The balloon catheter 1 has a shaft 2 and a balloon 10 provided on the outside of the shaft 2. The balloon catheter 1 has a proximal side and a distal side, and the balloon 10 is provided on the distal portion of the shaft 2. The proximal side of the balloon catheter 1 refers to the direction toward the user (operator) in the direction of extension of the balloon catheter 1, and the distal side refers to the opposite direction from the proximal side, i.e., the direction toward the treatment target. The direction from the proximal side to the distal side of the balloon catheter 1 is referred to as the longitudinal axis direction.

[0012] The balloon catheter 1 is configured so that fluid is supplied to the interior of the balloon 10 through the shaft 2, and the inflation and deflation of the balloon 10 can be controlled using an indeflator (a balloon pressurizer / depressurizer). The fluid may be pressurized fluid pressurized by a pump or the like. Hereinafter, the fluid supplied to the interior of the balloon 10 will be referred to as the "balloon inflation fluid."

[0013] The shaft 2 is composed of, for example, an inner shaft 3 and an outer shaft 4. The inner shaft 3 is disposed within the lumen of the outer shaft 4. The inner shaft 3 can function as a passage for a guide wire that guides the advancement of the shaft 2, and when the balloon catheter 1 is in use, the guide wire is inserted into the lumen of the inner shaft 3. The space between the inner shaft 3 and the outer shaft 4 can function as a flow path for the balloon inflation fluid.

[0014] In the rapid exchange type balloon catheter 1, a guidewire port 7 is provided midway from the distal side to the proximal side of the shaft 2, and the proximal end of the inner shaft 3 is connected to the guidewire port 7, and the distal end of the inner shaft 3 extends to the distal portion of the shaft 2, thereby forming a guidewire insertion passage extending from the guidewire port 7 to the distal portion of the shaft 2.

[0015] The outer shaft 4 may have a proximal outer shaft 4A and a distal outer shaft 4B. In this case, it is preferable that the inner shaft 3 is disposed in the lumen of the distal outer shaft 4B. The proximal outer shaft 4A and the distal outer shaft 4B may be made of the same material, or may be made of different materials. For example, it is preferable that the proximal outer shaft 4A is made of resin or metal, and the distal outer shaft 4B is made of resin. Note that the outer shaft 4 may not be divided into the proximal outer shaft 4A and the distal outer shaft 4B, but may be made of a single member, or the proximal outer shaft 4A and the distal outer shaft 4B may each be made of multiple tubular members.

[0016] A hub 5 is preferably provided on the proximal side of the shaft 2. The hub 5 preferably has a fluid injection section 6 that communicates with a flow path for balloon inflation fluid in the shaft 2. The balloon 10, shaft 2 (inner shaft 3, outer shaft 4), and hub 5 can be joined together using conventional joining means such as adhesives or thermal welding.

[0017] Although not shown in the drawings, the balloon catheter may be an over-the-wire type balloon catheter in which an inner shaft extends from the distal to the proximal end of the shaft and a guidewire insertion passage is formed from the distal to the proximal end of the shaft. In this case, a flow path for a balloon inflation fluid and a guidewire insertion passage provided in the shaft preferably extend to a hub, and the hub preferably has a fluid injection portion communicating with the flow path for the balloon inflation fluid and a treatment portion communicating with the guidewire insertion passage. Preferably, the hub has a bifurcated structure, with the fluid injection portion provided on one side and the treatment portion provided on the other side.

[0018] It is preferable that the outer surface of the shaft 2 is coated. In a rapid exchange type balloon catheter 1, it is preferable that the outer surface of one or both of the proximal outer shaft 4A and the distal outer shaft 4B is coated, and it is more preferable that the outer surfaces of both the proximal outer shaft 4A and the distal outer shaft 4B are coated. In an over-the-wire type balloon catheter, it is preferable that the outer surface of the outer shaft is appropriately coated.

[0019] The coating can be a hydrophilic coating or a hydrophobic coating depending on the purpose. The outer surface of the shaft 2 can be coated by immersing the shaft 2 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer surface of the shaft 2, or covering the outer surface of the shaft 2 with a hydrophilic or hydrophobic coating agent. The coating agent may contain drugs or additives.

[0020] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether-maleic anhydride copolymers, as well as hydrophilic coating agents made from any combination of these.

[0021] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0022] A distal tip 8 is preferably provided at the distal end of the balloon catheter 1. The distal tip 8 may be provided as a separate member from the inner shaft 3, on a more distal side than the distal end of the inner shaft 3, or the inner shaft 3 may extend distally beyond the distal end of the balloon 10, so that the distal end of the inner shaft 3 functions as the distal tip 8.

[0023] To enable confirmation of the position of the balloon 10 under X-ray fluoroscopy, a radiopaque marker 9 may be placed on the shaft 2 at the portion where the balloon 10 is located in the longitudinal direction. The radiopaque marker 9 may be placed, for example, on the inner shaft 3 placed inside the balloon 10, and is preferably placed at positions corresponding to both ends of the straight tube portion of the balloon 10, or may be placed at a position corresponding to the center of the straight tube portion of the balloon 10.

[0024] The balloon 10 has a longitudinal axis direction and a radial direction, and is formed in a cylindrical shape with openings on the proximal and distal sides. The radial direction of the balloon 10 refers to a direction perpendicular to the longitudinal axis direction, extending radially from the center of the balloon 10. The balloon 10 also has a circumferential direction, which is the direction along the outer periphery of the balloon 10 in an expanded state in a vertical cross section of the balloon 10 in the longitudinal axis direction.

[0025] As shown in Figures 4 and 7, the balloon 10 is configured with wires 17 disposed radially outward from the balloon body 16. The balloon 10 has a straight tube section 13, a proximal tapered section 12 located proximal to the straight tube section 13, and a distal tapered section 14 located distal to the straight tube section 13 in the longitudinal direction. In the straight tube section 13, the balloon body 16 is formed into a generally cylindrical shape extending in the longitudinal direction and has the largest radial length (outer diameter) in the balloon 10. The proximal tapered section 12 is located proximal to the straight tube section 13 and connects to the proximal end of the straight tube section 13. In the proximal tapered section 12, the balloon body 16 is formed so that the outer diameter decreases with increasing distance from the straight tube section 13. The distal tapered section 14 is located distal to the straight tube section 13 and connects to the distal end of the straight tube section 13. In the distal tapered section 14, the balloon body 16 is formed so that the outer diameter decreases with increasing distance from the straight tube section 13. Note that the shapes of the straight tube section 13, proximal tapered section 12, and distal tapered section 14 of the balloon body 16 described here represent the shapes of the balloon 10 in its expanded state.

[0026] The balloon 10 preferably further has a proximal sleeve portion 11 located proximal to the proximal tapered portion 12 and a distal sleeve portion 15 located distal to the distal tapered portion 14. The proximal sleeve portion 11 is located proximal to the proximal tapered portion 12 and connects to the proximal end of the proximal tapered portion 12. In the proximal sleeve portion 11, the balloon body portion 16 is formed in a substantially cylindrical shape. The distal sleeve portion 15 is located distal to the distal tapered portion 14 and connects to the distal end of the distal tapered portion 14. In the distal sleeve portion 15, the balloon body portion 16 is formed in a substantially cylindrical shape.

[0027] By configuring the balloon 10 as described above, when the balloon 10 is inflated at a stricture, the straight tube portion 13 comes into sufficient contact with the stricture, facilitating treatment such as dilating the stricture. Furthermore, because the balloon 10 has the proximal tapered portion 12 and the distal tapered portion 14, the outer diameters of the proximal and distal ends of the balloon 10 can be reduced when the balloon 10 is deflated, thereby reducing the difference in level between the shaft 2 and the balloon 10, making it easier to insert the balloon 10 into a body cavity, a forceps channel of an endoscope, or a delivery catheter such as a guiding catheter.

[0028] In the distal portion of the shaft 2, the inner shaft 3 preferably extends distally beyond the distal end of the outer shaft 4, and the inner shaft 3 preferably extends through the interior space of the balloon 10 from the proximal sleeve portion 11 to the distal sleeve portion 15. The outer surface of the inner shaft 3 preferably joins to the inner surface of the distal sleeve portion 15 of the balloon 10, and the outer surface of the outer shaft 4 preferably joins to the inner surface of the proximal sleeve portion 11 of the balloon 10. By configuring the distal portion of the shaft 2 in this manner, balloon inflation fluid can be supplied to the interior space of the balloon 10 through the space between the inner shaft 3 and the outer shaft 4.

[0029] In a vertical cross section of the balloon 10 in the longitudinal axis direction, the outer shape of the balloon body 16 is preferably formed to be substantially circular. In the straight tube section 13, the outer surface of the balloon body 16 is preferably formed to be cylindrical.

[0030] In the straight tube section 13, the outer surface of the balloon main body 16 is preferably formed flat, and for example, the outer surface of the balloon main body 16 is preferably not formed with a recess. In the straight tube section 13, the outer surface of the balloon main body 16 is formed flat, meaning that the cylindrical outer surface is free of irregularities. This irregularity does not include surface roughness that is unavoidable during manufacturing. In the balloon 10, the outer surfaces of the proximal tapered section 12 and the distal tapered section 14 are also preferably formed flat.

[0031] There are no particular limitations on the size of the balloon main body 16. The size of the balloon main body 16 can be set appropriately, for example, such that the length of the straight tube portion 13 in the longitudinal direction is in the range of 4 mm to 400 mm, and the outer diameter of the straight tube portion 13 is in the range of 1 mm to 30 mm.

[0032] The balloon body 16 is preferably made of a resin, more preferably a thermoplastic resin. This facilitates the manufacturing of the balloon body 16 by molding. Examples of resins that can be used to form the balloon body 16 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomer; polyurethane resins such as polyurethane and polyurethane elastomer; polyphenylene sulfide resins; polyamide resins such as polyamide and polyamide elastomer; fluorine-based resins; silicone resins; and natural rubbers such as latex rubber. These resins may be used alone or in combination. Among these, polyamide resins, polyester resins, and polyurethane resins are preferred. Elastomer resins are particularly preferred in terms of the thinness and flexibility of the balloon body 16. Among polyamide resins, nylon 12 and nylon 11 are preferred materials for the balloon body 16. Nylon 12 is preferred because it can be easily molded during blow molding. Furthermore, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferably used in terms of thinning and flexibility of the balloon body 16. Among these, polyether ester amide elastomers are preferably used in terms of high yield strength and good dimensional stability of the balloon body 16.

[0033] The balloon 10 has wires 17 disposed radially outward from the balloon body 16. The wires 17 can provide the balloon 10 with a scoring function or partially inhibit expansion of the balloon 10. In the former case, for example, when the balloon 10 is inflated at a stenotic portion of a blood vessel, the wires 17 are pushed radially outward as the balloon body 16 expands, penetrating into the calcified stenotic portion and creating cracks in the stenotic portion. This allows the stenotic portion to be dilated while suppressing vascular dissection. In the latter case, when the balloon 10 is inflated, the wires 17 inhibit expansion of the balloon 10 at the locations where the wires 17 are disposed, which can serve as the starting point for fracture of the drug layer 22 provided on the outer surface of the balloon 10, as described below. The balloon 10 can also be used to treat stenoses or lesions in body cavities other than blood vessels. However, the following description focuses on the application of the balloon 10 to vascular treatment.

[0034] The wire 17 can be made of, for example, a resin. Examples of resins that make up the wire 17 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate; polyamide resins such as nylon; aromatic polyether ketone resins such as PEEK; polyurethane resins; polyether polyamide resins; polyimide resins; polyamide imide resins; fluorine-based resins such as PTFE, PFA, and ETFE; polyvinyl chloride resins; and silicone resins. These resins may be used alone or in combination of two or more. The wire 17 and the balloon main body 16 may be made of the same resin or different resins.

[0035] The wire 17 may be made of a metal or a combination of a metal and a resin. Examples of metals constituting the wire 17 include stainless steel such as SUS304 and SUS316, carbon steel, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, nickel-titanium alloys, cobalt-chromium alloys, and tungsten alloys. These may be used alone or in combination of two or more.

[0036] The cross-sectional shape of the wire 17 is not particularly limited. For example, the shape of the wire 17 in a cross section perpendicular to the extending direction of the wire 17 may be circular, elliptical, oval, polygonal, irregular, etc. Polygons include polygons with clear corner vertices and straight sides, as well as rounded polygons with rounded corners and polygons with at least some curved sides. The wire 17 may be a solid wire or a twisted wire.

[0037] The wire 17 is disposed at least radially outward from the straight tube portion 13 of the balloon body 16. This allows the wire 17 to penetrate deeply into the narrowed portion of the blood vessel when the balloon 10 is expanded, enhancing the scoring function of the wire 17. Alternatively, the wire 17 can partially and effectively suppress the expansion of the balloon 10 when the balloon 10 is expanded.

[0038] It is preferable that at least a portion of the wire 17 disposed radially outward from the straight tube section 13 of the balloon body 16 is not fixed to the balloon body 16. The wire 17 may also be disposed radially outward from the proximal tapered section 12 and / or the distal tapered section 14 of the balloon body 16, or may also be disposed radially outward from the proximal sleeve section 11 and / or the distal sleeve section 15 of the balloon body 16.

[0039] Only one wire 17 may be provided on the radially outer side of the balloon body 16, or two or more wires 17 may be provided. To maximize the effect of the wires 17, two or more wires 17 are preferably provided, three or more are more preferable, and ten or fewer wires are preferably provided, and eight or fewer wires are more preferable.

[0040] In the balloon 10, the wires 17 may extend obliquely relative to the longitudinal axis direction, as shown in Figures 4 and 7, or, although not shown in the drawings, may extend parallel to the longitudinal axis direction, extend parallel to the circumferential direction, or may extend in a plurality of different directions. When the wires 17 extend obliquely relative to the longitudinal axis direction of the balloon 10, it is preferable that the wires 17 extend spirally in the longitudinal axis direction on the outer surface of the balloon body 16.

[0041] When the balloon 10 is inflated, whether the wires 17 are pushed radially outward by the balloon body 16 and expand together with the balloon body 16 or act to partially suppress the expansion of the balloon body 16 is determined by the materials constituting the balloon body 16 and the wires 17, the arrangement of the wires 17, etc. If the balloon body 16 is made of a relatively hard material and the wires 17 are made of an elastic material, the wires 17 will be more likely to be pushed radially outward as the balloon body 16 expands. If the balloon body 16 is made of a relatively soft material and the wires 17 are made of a relatively hard material, the wires 17 will be more likely to dig into the outer surface of the expanded balloon body 16 as the balloon body 16 expands, thereby partially suppressing the expansion of the balloon body 16. Furthermore, if the wire 17 is positioned in contact with the outer surface of the balloon main body 16 when the balloon 10 is contracted, the wire 17 will be more likely to dig into the outer surface of the expanded balloon main body 16 when the balloon main body 16 is expanded, and if the wire 17 is positioned away from the outer surface of the balloon main body 16 when the balloon 10 is contracted, the wire 17 will be more likely to be pushed outward radially without digging into the outer surface of the balloon main body 16 when the balloon main body 16 is expanded.

[0042] A drug layer is provided on the outer surface of balloon 10, which will be described with reference to Figures 5, 6, 8, and 9. Figure 5 is a vertical cross-sectional view of the balloon in the longitudinal axis direction shown in Figure 4, showing a cross-sectional view of the balloon with a drug layer provided on the surface of the balloon, Figure 6 is an enlarged cross-sectional view of the balloon around the wire material shown in Figure 5, Figure 8 is a cross-sectional view of the balloon in the longitudinal axis direction and radial direction shown in Figure 7, showing a cross-sectional view of the balloon with a drug layer provided on the surface of the balloon, and Figure 9 is an enlarged cross-sectional view of the balloon around the wire material shown in Figure 8.

[0043] The balloon 10 is provided with a drug layer 22 extending from the surface of the wire 17 to the outer surface of the balloon body 16. The drug contained in the drug layer 22 is not particularly limited as long as it is a pharmacologically active substance, and examples include medicaments acceptable as medicaments such as gene therapy drugs, non-gene therapy drugs, small molecules, and cells. In particular, when the catheter 1 is used for the purpose of suppressing vascular restenosis after angioplasty, anti-restenosis drugs such as antiproliferative agents and immunosuppressants are preferably used as the drug. Specifically, drugs such as paclitaxel, sirolimus (rapamycin), everolimus, and zotarolimus can be used. These drugs may be used alone or in combination of two or more types.

[0044] In addition to the pharmacologically active substance, the drug layer 22 may contain an auxiliary agent for improving the dispersibility, solubility, migration to the vascular wall, and storage stability of the drug. Examples of the auxiliary agent include a stabilizer, a binder, a disintegrant, a moisture-proofing agent, a preservative, and a dissolution aid. Specific examples include lactose, sucrose, maltose, dextrin, xylitol, erythritol, mannitol, ethylenediamine, potassium iodide, urea, polysorbate, dibutylhydroxytoluene, polyethylene glycol, lipids, sodium pyrosulfite, ascorbic acid, tocopherol, benzoic acid, parahydroxybenzoic acid esters, polyacrylic acid, polylactic acid, polyglycolic acid, hyaluronic acid, chitosan, and gelatin.

[0045] The drug constituting the drug layer 22 is preferably crystalline, and it is particularly preferred that the pharmacologically active substance be crystalline. Examples of crystalline pharmacologically active substances include paclitaxel, sirolimus (rapamycin), everolimus, and zotarolimus. It is also preferred that the auxiliary agent or protective agent contained together with the pharmacologically active substance be crystalline. Examples of crystalline auxiliary agents or protective agents include salts such as sugar, urea, and potassium iodide, ascorbic acid, polylactic acid, and polyglycolic acid. This increases the brittleness of the drug layer 22, making the drug layer 22 more likely to peel off from the outer surface of the balloon 10 when the balloon 10 is inflated.

[0046] A protective layer may be provided on the outer surface of the drug layer 22 to prevent the drug from leaching or falling off into bodily fluids during delivery of the balloon 10 to the stricture site. The protective layer may be composed of, for example, a hydrophilic component. For example, when delivering the balloon 10 to a body cavity containing a bodily fluid rich in lipid-soluble components, such as a bile duct, a protective layer composed of a hydrophilic component provided on the outer surface of the drug layer 22 can prevent dissolution of the protective layer upon contact with bodily fluids, thereby enabling the protective layer to protect the drug layer 22. Examples of hydrophilic components include hydrophilic polymers such as carboxymethyl cellulose, hydroxypropyl cellulose, methyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, alginic acid, pectin, gum arabic, gellan gum, guar gum, xanthan gum, carrageenan, gelatin, polyethylene glycol, hyaluronic acid, and sodium polyacrylate; salts such as potassium chloride and ammonium acetate; amino acids such as glycine and glutamic acid; sugars such as glucose and fructose; and urea. The protective layer may also be composed of a hydrophobic component. For example, when the balloon 10 is delivered into a body cavity containing a body fluid with a high water content, such as a blood vessel containing blood, if a protective layer made of a hydrophobic component is provided on the outer surface of the drug layer 22, dissolution of the protective layer upon contact with the body fluid is suppressed, and the protective layer can perform its protective function for the drug layer 22. Examples of hydrophobic components include lipid compounds such as lecithin, propylene glycol stearate, cholesterol, and terpenes, hydrocarbon compounds such as petrolatum, hydrophobic (meth)acrylic polymers such as polyethyl acrylate and polymethyl methacrylate, hydrophobic polyester polymers such as polylactic acid and polyglycolic acid, and silicone oil.

[0047] Even when the balloon 10 is delivered to a body cavity containing a body fluid with a high water content, such as a blood vessel containing blood, the protective layer is preferably made of the aforementioned hydrophilic component, particularly a high-molecular-weight hydrophilic polymer. Using a high-molecular-weight hydrophilic polymer as the protective layer can prevent dissolution of the protective layer due to the water content of the body fluid, thereby making it easier to maintain the protective function of the drug layer 22.

[0048] The protective layer is preferably amorphous, which can enhance the protective function of the protective layer. Examples of components of the amorphous protective layer include hydrophilic polymers such as hyaluronic acid and sodium poly(meth)acrylate, hydrophobic polyester polymers such as D,L-polylactic acid and lactic acid-glycolic acid copolymer, and lipid compounds such as lecithin.

[0049] Drug layer 22 is formed thicker near wire 17. For example, in a case where wire 17 extends obliquely at an angle of 45° or less with respect to the longitudinal axis direction in straight tube section 13 as shown in Fig. 4, or in a case where wire 17 extends parallel to the longitudinal axis direction in straight tube section 13 (not shown in the drawings) (hereinafter, these cases will be referred to as the "first embodiment"), in a vertical cross section of straight tube section 13 taken along the longitudinal axis direction, as shown in Fig. 6, maximum thickness T1 of drug layer 22 in specific region 19 surrounded by specific shape 18 obtained by enlarging the outer periphery of wire 17 by a factor of two around centroid 17C of the outer periphery of wire 17 is thicker than maximum thickness T2 of drug layer 22 on the outer surface of balloon main body 16 outside specific region 19. On the other hand, as shown in Figure 7, when the wire 17 in the straight tube section 13 extends obliquely at an angle of more than 45° with respect to the longitudinal axis direction, or when the wire 17 in the straight tube section 13 extends parallel to the circumferential direction, although this is not shown in the drawings (hereinafter these will be referred to as the "second embodiment"), as shown in Figure 9, in a cross section along the longitudinal axis direction and radial direction of the straight tube section 13, the maximum thickness T1 of the drug layer 22 in a specific region 19 surrounded by a specific shape 18 obtained by enlarging the outer edge of the cross section of the wire 17 by two times, centered on the centroid 17C of the outer edge of the cross section, is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 outside the specific region 19. The angle between the extension direction of the wire 17 and the longitudinal axis direction is in the range of 0° to 90°, and in the first embodiment, the wire 17 extends at an angle of 0° or more and 45° or less with respect to the longitudinal axis direction, and in the second embodiment, the wire 17 extends at an angle of more than 45° and 90° or less with respect to the longitudinal axis direction.

[0050] By providing drug layer 22 in this manner, when balloon 10 is expanded at a stenosis, the drug can be efficiently transferred to the inner surface of the blood vessel wall. For example, when balloon 10 is expanded at a stenosis, wire 17 penetrates the stenosis, effectively expanding the stenosis. Furthermore, since drug layer 22 is thick around wire 17, the drug can be efficiently transferred from the inner surface of the blood vessel wall to the interior of the expanded stenosis. Alternatively, if wire 17 functions to partially suppress the expansion of balloon 10, the thicker drug layer 22 around wire 17 can be effectively ruptured when balloon 10 is expanded. This allows the drug to be efficiently transferred to the blood vessel wall.

[0051] The specific shape 18 that defines the outer edge of the specific region 19 is determined by doubling the cross-sectional outer edge of the wire rod 17, centered on a centroid 17C of the cross-sectional outer edge of the wire rod 17, in a vertical cross section in the longitudinal direction of the straight pipe portion 13 or in a cross section along the longitudinal direction and radial direction of the straight pipe portion 13. Therefore, the area of ​​the specific region 19 surrounded by the specific shape 18 is four times the cross-sectional area of ​​the wire rod 17.

[0052] The maximum thickness T1 of drug layer 22 within specific region 19 is determined as follows: At a specific point on the radially inner surface of drug layer 22 within specific region 19 (including the boundary of specific region 19), the shortest length of a line segment connecting the specific point to the radially outer surface of drug layer 22 within specific region 19 (however, the line segment does not cross the cross section of wire 17 or extend beyond specific region 19) is defined as the thickness of drug layer 22 at the specific point. This is applied to all points along the inner surface of drug layer 22 within specific region 19 to measure the thickness, and the largest value among them is defined as the maximum thickness T1 of drug layer 22 in specific region 19.

[0053] The maximum thickness T2 of drug layer 22 on the outer surface of balloon body 16 outside specific region 19 is determined as follows: In the portion of drug layer 22 on the outer surface of balloon body 16 outside specific region 19, the shortest length of a line segment connecting a specific point on the inner surface of drug layer 22 outside specific region 19 to the radially outer surface of drug layer 22 outside specific region 19 (however, this line segment does not cross specific region 19) is defined as the thickness of drug layer 22 at that specific point. This is applied to all points along the inner surface of drug layer 22 outside specific region 19, and the largest value among these measurements is defined as the maximum thickness T2 of drug layer 22 on the outer surface of balloon body 16 outside specific region 19.

[0054] The maximum thickness T1 of the drug layer 22 within the specific region 19 is preferably at least 1.2 times, more preferably at least 1.5 times, and even more preferably at least 1.8 times the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 other than the specific region 19. There is no particular upper limit to the ratio of the maximum thickness T1 of the drug layer 22 within the specific region 19 to the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 other than the specific region 19, and the drug layer 22 may be absent or may be present at a very thin thickness on the outer surface of the balloon body 16 other than the specific region 19. For example, the maximum thickness T1 of the drug layer 22 within the specific region 19 may be no more than 100 times, or may be no more than 50 times, no more than 30 times, no more than 20 times, or no more than 10 times the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 other than the specific region 19.

[0055] When the wire 17 extends to include both the first and second embodiments, for the wire 17 of the first embodiment, the maximum thicknesses T1 and T2 of the drug layer 22 are determined in a vertical cross section along the longitudinal axis of the straight tube section 13, and the sizes of these are compared; for the wire 17 of the second embodiment, the maximum thicknesses T1 and T2 of the drug layer 22 are determined in a cross section along the longitudinal axis and radial directions of the straight tube section 13, and the sizes of these are compared.

[0056] In the balloon 10, it is sufficient that the maximum thickness T1 of the drug layer 22 within the specific region 19 is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 outside the specific region 19, on at least a portion of the outer surface of the straight tube section 13. In the first embodiment, it is preferable that the drug layer 22 be formed in this manner over at least a portion of the central half of the straight tube section 13 in the longitudinal direction, more preferably over at least half of the central half of the straight tube section 13 in the longitudinal direction, and even more preferably over at least two-thirds of the central half of the straight tube section 13 in the longitudinal direction. For example, when the relative position in the longitudinal direction of straight tube section 13 is taken as 0% at the proximal end of straight tube section 13 and 100% at the distal end, a range of 25% to 75% of straight tube section 13 is cut perpendicular to the longitudinal direction at six locations at 10% increments, and the thickness of drug layer 22 at each cut surface is measured, and it is preferable that drug layer 22 is formed in this manner at three or more locations. This makes it possible to determine that, in at least half of the central half of straight tube section 13 in the longitudinal direction, maximum thickness T1 of drug layer 22 within specific region 19 is formed thicker than maximum thickness T2 of drug layer 22 on the outer surface of balloon main body 16 outside specific region 19. The drug layer 22 may be formed so that the maximum thickness T1 of the drug layer 22 within the specific region 19 is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 outside the specific region 19 throughout the central half region in the longitudinal direction of the straight tube section 13, and the drug layer 22 may be formed in this manner throughout the entire longitudinal direction of the straight tube section 13.

[0057] In the second embodiment, it is sufficient that the maximum thickness T1 of the drug layer 22 within the specific region 19 is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 outside the specific region 19 in at least a portion of the straight tube section 13 in the circumferential direction. The drug layer 22 is preferably formed in this manner over at least half of the circumferential direction of the straight tube section 13, and more preferably over at least two-thirds of the circumferential direction of the straight tube section 13. For example, the straight tube section 13 is cut at six locations along the longitudinal axis at positions dividing the straight tube section 13 into six equal parts in the circumferential direction, and the thickness of the drug layer 22 at each cut surface is measured. It is preferable that the drug layer 22 is formed in this manner in at least three locations. This allows it to be determined that the maximum thickness T1 of the drug layer 22 within the specific region 19 is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 outside the specific region 19 in at least half of the circumferential direction of the straight tube section 13. The drug layer 22 may be formed such that, throughout the entire circumferential direction of the straight tube portion 13, the maximum thickness T1 of the drug layer 22 within the specific region 19 is thicker than the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body portion 16 outside the specific region 19.

[0058] In the various explanations below regarding the formation of the drug layer 22, the above explanations also apply to the formation of the drug layer 22 in the longitudinal axis direction or circumferential direction of the straight tube section 13.

[0059] Drug layer 22 around wire 17 is preferably formed thicker on the radially inner side. Specifically, in the first embodiment, as shown in Fig. 6, in a vertical cross section of straight tube section 13 taken along the longitudinal axis direction, the maximum thickness of drug layer 22 in region 19A, the radially inner half of specific region 19, is preferably thicker than the maximum thickness of drug layer 22 in region 19B, the radially outer half of specific region 19. In the second embodiment, as shown in Fig. 9, in a cross section of straight tube section 13 taken along the longitudinal axis direction and the radial direction, the maximum thickness of drug layer 22 in region 19A, the radially inner half of specific region 19, is preferably thicker than the maximum thickness of drug layer 22 in region 19B, the radially outer half of specific region 19.

[0060] The boundary between the radially inner half region 19A and the radially outer half region 19B of the specific region 19 is determined as follows: The innermost and outermost radial points where a line passing through the centroid 17C of the cross-sectional outer edge of the wire 17 and extending radially overlaps the cross-section of the wire 17 are determined, and the midpoint between these points is found. A curve or line passing through the midpoint and parallel to the outer surface of the balloon body 16 is defined as the boundary between the radially inner half region 19A and the radially outer half region 19B of the specific region 19. In Figures 6 and 9, the boundary between the radially inner half region 19A and the radially outer half region 19B of the specific region 19 is represented by a two-dot chain line.

[0061] If drug layer 22 is provided around wire 17 in this manner, wire 17 can easily penetrate the stenotic portion when balloon 10 is inflated at the stenotic portion. This allows balloon 10 to effectively dilate the stenotic portion. Furthermore, when wire 17 penetrates the stenotic portion of the blood vessel, the drug is primarily transferred to the inner surface of the blood vessel wall and a relatively shallow portion within the vessel wall, thereby inhibiting migration of smooth muscle cells present in the tunica media of the blood vessel wall to the inner surface of the blood vessel. If wire 17 functions to partially restrict the expansion of balloon 10, drug layer 22, which is thicker on the radially inward side around wire 17, can be effectively ruptured when balloon 10 is inflated. This allows the drug to be efficiently transferred to the blood vessel wall.

[0062] The maximum thickness of drug layer 22 in region 19A, the radially inner half of specific region 19, is preferably, for example, 1.5 times or more, more preferably 2.0 times or more, and even more preferably 2.5 times or more, the maximum thickness of drug layer 22 in region 19B, the radially outer half of specific region 19. There is no particular upper limit to the ratio of the maximum thickness of drug layer 22 in region 19A, the radially inner half of specific region 19, to the maximum thickness of drug layer 22 in region 19B, the radially outer half of specific region 19, and drug layer 22 may not be provided in region 19B, the radially outer half of specific region 19, or may be present with a very thin thickness. For example, the maximum thickness of the drug layer 22 in region 19A, which is the radially inner half of the specific region 19, may be 100 times or less, or may be 50 times or less, 30 times or less, 20 times or less, or 10 times or less, of the maximum thickness of the drug layer 22 in region 19B, which is the radially outer half of the specific region 19.

[0063] The maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 other than the specific region 19 is preferably greater than the maximum thickness of the drug layer 22 in region 19B, the radially outer half of the specific region 19. Specifically, in the first embodiment, as shown in Fig. 6 , in a vertical cross section of the straight tube section 13 taken along the longitudinal axis, the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 other than the specific region 19 is preferably greater than the maximum thickness of the drug layer 22 in region 19B, the radially outer half of the specific region 19. In the second embodiment, as shown in Fig. 9 , in a cross section of the straight tube section 13 taken along the longitudinal axis and the radial direction, the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon main body 16 other than the specific region 19 is preferably greater than the maximum thickness of the drug layer 22 in region 19B, the radially outer half of the specific region 19. In this case, the drug layer 22 is provided to some extent not only around the wire 17 but also on the outer surface of the balloon body 16, allowing the drug to be delivered to a wide area of ​​the blood vessel wall when the balloon 10 is inflated.

[0064] The maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 outside the specific region 19 is preferably at least 1.2 times, more preferably at least 1.5 times, and even more preferably at least 1.8 times, the maximum thickness of the drug layer 22 in the region 19B, the radially outer half of the specific region 19. The upper limit of the ratio of the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 outside the specific region 19 to the maximum thickness of the drug layer 22 in the region 19B, the radially outer half of the specific region 19, is not particularly limited. The drug layer 22 may not be provided in the region 19B, the radially outer half of the specific region 19, or may be very thin. For example, the maximum thickness T2 of the drug layer 22 on the outer surface of the balloon body 16 outside the specific region 19 may be no more than 100 times, no more than 50 times, no more than 30 times, no more than 20 times, or no more than 10 times the maximum thickness of the drug layer 22 in the region 19B, the radially outer half of the specific region 19.

[0065] Preferably, cracks extending along the extension direction of wire 17 are formed on the surface of drug layer 22. Figure 10 shows an example of a configuration in which cracks 24 are formed in drug layer 22 in the cross-sectional view of balloon 10 shown in Figure 6. By forming cracks 24 on the surface of drug layer 22, when drug layer 22 comes into contact with the inner surface of the blood vessel wall when balloon 10 is expanded at the stenosis site, drug layer 22 extending from the surface of wire 17 to the outer surface of balloon body 16 is likely to peel off from the surface of balloon 10 starting from cracks 24, facilitating migration of drug layer 22 from the surface of balloon 10 toward the blood vessel wall.

[0066] The cracks 24 may be formed to extend parallel to the extension direction of the wire 17 when viewed from the outside of the balloon 10, or at least a portion of the cracks 24 may be formed to extend obliquely to the extension direction of the wire 17. It is sufficient that the cracks 24 are formed to extend along the extension direction of the wire 17 as a whole. The cracks 24 may be formed to extend continuously along the wire 17, or may be formed to extend intermittently. Furthermore, multiple cracks 24 extending along the wire 17 may be arranged partially side by side with each other.

[0067] Cracks 24 may be formed to extend from the surface of drug layer 22 to the surface of wire 17 or the outer surface of balloon body 16, or may be formed to extend from the surface of drug layer 22 to terminate inside drug layer 22. Cracks 24 on the surface of drug layer 22 are preferably formed within specific region 19. More preferably, cracks 24 are entirely contained within specific region 19. By forming cracks 24 in this manner, drug layer 22 provided on the surface of wire 17 is more likely to peel from the surface of balloon 10 starting from cracks 24 when balloon 10 is expanded at the stenosis site.

[0068] As shown in Figure 11, a protective layer 25 may be provided on the outer surface of the drug layer 22, and the protective layer 25 may be provided to cover at least a portion of the cracks 24. Figure 11 shows an example of a configuration in which the protective layer 25 is provided on the outer surface of the drug layer 22 so as to cover the cracks 24 in the cross-sectional view of the balloon 10 shown in Figure 10. By providing the protective layer 25 on the outer surface of the drug layer 22 so as to cover at least a portion of the cracks 24, it is possible to prevent bodily fluids from entering the cracks 24 during delivery of the balloon 10 to the stenotic area, which could cause the drug layer 22 to fall off or the drug to elute from the drug layer 22. The protective layer 25 is preferably provided on the outer surface of the drug layer 22 so as to cover the entire cracks 24. Alternatively, the protective layer 25 is preferably provided so as to penetrate into the cracks 24 and fill at least a portion of the cracks 24.

[0069] A drug layer 22 is preferably present between the wire rod 17 and the balloon body 16. Specifically, in the first embodiment, as shown in FIG. 6 , in a vertical cross section of the straight tube section 13 taken along the longitudinal axis, the drug layer 22 is preferably present between the outer edge of the cross section of the wire rod 17 facing the outer surface of the balloon body 16 and the outer surface of the balloon body 16. In the second embodiment, as shown in FIG. 9 , in a cross section of the straight tube section 13 taken along the longitudinal axis and radial directions, the drug layer 22 is preferably present between the outer edge of the cross section of the wire rod 17 facing the outer surface of the balloon body 16 and the outer surface of the balloon body 16. The outer edge of the cross section of the wire rod 17 facing the outer surface of the balloon body 16 refers to the portion of the outer edge of the cross section of the wire rod 17 facing the balloon body 16 on the radially inward side. If the drug layer 22 is provided in this manner, when the balloon 10 is inflated, the wire rod 17 is pressed against the outer surface of the balloon body 16, making the drug layer 22 present between the wire rod 17 and the balloon body 16 more likely to rupture. This allows the drug to be easily detached from the balloon 10, allowing the drug to be efficiently transferred to the blood vessel wall.

[0070] Preferably, a drug layer 22 is present between the wire rod 17 and the balloon body 16, but a gap 23 where the drug layer 22 is not present is present between the wire rod 17 and the balloon body 16. Specifically, in the first embodiment, as shown in Fig. 6 , in a vertical cross section of the straight tube section 13 taken along the longitudinal axis, a drug layer 22 is present between the outer edge of the cross section of the wire rod 17 facing the outer surface of the balloon body 16 and the outer surface of the balloon body 16, but a gap 23 where the drug layer 22 is present but no drug layer 22 is present is present between the outer edge of the cross section of the wire rod 17 facing the outer surface of the balloon body 16 and the outer surface of the balloon body 16, but a gap 23 where the drug layer 22 is present but no drug layer 22 is present is present between the wire rod 17 and the balloon body 16, but a gap 23 where the drug layer 22 is present but no drug layer 22 is present is present between the wire rod 17 and the balloon body 16 and the balloon body 16 when the balloon 10 is inflated. Furthermore, blood or the like flows into the gap 23 where the drug layer 22 does not exist, making the drug layer 22 present between the wire 17 and the balloon body 16 more likely to detach from the balloon 10 .

[0071] The drug layer 22 is preferably provided on the outer surface of the balloon body 16 other than the specific region 19. In the first embodiment, in a vertical cross section of the straight tube section 13 taken along the longitudinal axis, the drug layer 22 is preferably provided over 30% or more of the outer surface of the balloon body 16 other than the specific region 19, more preferably 40% or more, and even more preferably 50% or more. In the second embodiment, in a cross section of the straight tube section 13 taken along the longitudinal axis and radial directions, the drug layer 22 is preferably provided over 30% or more of the outer surface of the balloon body 16 other than the specific region 19, more preferably 40% or more, and even more preferably 50% or more. In the first and second embodiments, the drug layer 22 may be provided over a wider area of ​​the outer surface of the balloon body 16, and may be provided over 60% or more, 80% or more, or even the entire outer surface of the balloon body 16 other than the specific region 19.

[0072] In a cross section perpendicular to the extension direction of the wire rod 17, the wire rod 17 is preferably formed so that the radially outer surface does not have a steep slope. This will be described with reference to FIG. 12 . FIG. 12 shows various cross-sectional configuration examples of the wire rod 17, and shows cross sections perpendicular to the extension direction of the wire rod 17. FIG. 12( a) shows a cross-sectional view of a wire rod 17 having a circular cross-section, FIG. 12( b) shows a cross-sectional view of a wire rod 17 having a rectangular cross-section, FIG. 12( c) shows a cross-sectional view of a wire rod 17 having a hexagonal cross-section, and FIG. 12( d) shows a cross-sectional view of a wire rod 17 having a pentagonal cross-section. In FIG. 12 , the lower side of the figure corresponds to the radially inner side, and the upper side of the figure corresponds to the radially outer side.

[0073] In the radially outer half of the cross section of wire 17, the widthwise length L1 of wire 17 is preferably at least twice the radial length L2. In each cross section of wire 17 shown in Figures 12(a) to 12(d), the radially inner half and the radially outer half are separated by a two-dot chain line, and the portion above the two-dot chain line is the radially outer half of the cross section of wire 17. In Figures 12(a) to 12(d), the widthwise length L1 of wire 17 in the radially outer half of the cross section of wire 17 is at least twice the radial length L2. If wire 17 has such a cross-sectional shape, the radially outer surface of wire 17 is formed so as not to have a steep slope. This makes it easier to provide drug layer 22 on the radially outer surface of wire 17. In the radially outer half of the cross section of the wire 17, the widthwise length L1 of the wire 17 may be 2.5 times or more or 3 times or more the radial length L2. On the other hand, in terms of improving the scoring function of the wire 17, the widthwise length L1 of the wire 17 in the radially outer half of the cross section of the wire 17 is preferably 8 times or less, more preferably 6 times or less, the radial length L2. The width direction of the wire 17 in the radially outer half of the cross section of the wire 17 means the direction perpendicular to a line passing through the centroid 17C of the outer half and extending radially.

[0074] Preferably, the wire 17 has its proximal and distal ends fixed to the balloon body 16 or the shaft 2, and the intermediate portion between the proximal and distal ends is not fixed to the balloon body 16 (see FIGS. 1, 4, and 7). This facilitates inflation of the balloon body 16 and, as will be described later, makes it easier to fold the balloon 10.

[0075] The proximal end of the wire 17 is preferably fixed to the proximal sleeve portion 11 and / or the proximal tapered portion 12, and the distal end of the wire 17 is preferably fixed to the distal sleeve portion 15 and / or the distal tapered portion 14. Furthermore, it is preferable that the intermediate portion of the wire 17 is not fixed to at least the straight tube portion 13 of the balloon body 16. Because this facilitates the provision of the wire 17, it is preferable that the wire 17 extend parallel to or obliquely from the longitudinal axis direction in the straight tube portion 13. The intermediate portion of the wire 17 may be not fixed to the proximal tapered portion 12 and / or the distal tapered portion 14, or may be not fixed to the proximal sleeve portion 11 and / or the distal sleeve portion 15.

[0076] In balloon 10, it is preferable that the surface free energy E1 of the material constituting the surface of wire 17 differs from the surface free energy E2 of the material constituting the outer surface of balloon body 16. Surface free energy affects wettability and compatibility with liquids; the higher the surface free energy, the better the compatibility with liquids; the lower the surface free energy, the more likely the material is to repel liquids. Drug layer 22 can be formed, for example, by coating the surface of balloon 10 with a drug solution and drying it. In this case, by appropriately setting the surface free energy E1 of the material constituting the surface of wire 17 and the surface free energy E2 of the material constituting the outer surface of balloon body 16, drug layer 22 can be selectively provided at desired locations on the surface of balloon 10.

[0077] The surface free energy E1 of the material constituting the surface of the wire 17 and the surface free energy E2 of the material constituting the outer surface of the balloon body 16 can be determined by measuring the contact angle of a droplet of each material in the gas phase or the contact angle of an air bubble in the liquid phase. The contact angle can be measured using a commercially available contact angle meter, and the surface free energy can be calculated from the contact angle measurement results.

[0078] The surface free energy E1 of the material constituting the surface of wire 17 is preferably greater than the surface free energy E2 of the material constituting the outer surface of balloon body 16. By setting the surface free energies of the materials constituting the surface of wire 17 and the outer surface of balloon body 16 in this manner, the drug solution becomes more easily intimately attached to the surface of wire 17, making it easier to form drug layer 22 thicker around wire 17.

[0079] The surface free energy E2 of the material constituting the outer surface of the balloon body 16 is preferably, for example, 30 dyne / cm or more and 60 dyne / cm or less. The surface free energy E2 is more preferably 35 dyne / cm or more, even more preferably 40 dyne / cm or more, and even more preferably 55 dyne / cm or less. If the surface free energy E2 is within this range, when a chemical solution is applied to the outer surface of the balloon body 16, the chemical solution is likely to remain sufficiently on the outer surface of the balloon body 16.

[0080] The surface free energy E1 of the material constituting the surface of wire 17 is preferably at least five times, more preferably at least eight times, and even more preferably at least ten times, the surface free energy E2 of the material constituting the outer surface of balloon body 16. Setting the surface free energy E1 of the material constituting the surface of wire 17 in this manner facilitates forming a thicker drug layer 22 around wire 17. There is no particular upper limit to the ratio of the surface free energy E1 to the surface free energy E2, and the surface free energy E1 may be 1,000 times or less, 500 times or less, 100 times or less, or 50 times or less the free energy E2.

[0081] When the balloon 10 is delivered to a treatment site such as a stenotic portion of a blood vessel, it is preferably inserted into a guiding catheter or sheath in a deflated state. At this time, it is preferable that the balloon 10 be appropriately folded so that its radial size is small.

[0082] 13 to 15 show examples of the configuration of the balloon 10 shown in FIG. 4 after it has been deflated and folded. As shown in FIGS. 13 to 15, when the balloon 10 is in a deflated state, the balloon 10 has folding wings 20 formed by folding the balloon body 16 with the inner surface facing inward, and the folding wings 20 are preferably arranged overlapping the outer surface of the balloon 10. The folding wings 20 are formed by folding the balloon body 16 along folding lines 21, with the balloon bodies 16 overlapping each other. At the folding lines 21, the balloon body 16 is folded with the inner surface facing inward. Therefore, when viewed from the outside of the balloon 10, the folding lines 21 form a mountain fold.

[0083] At the folding line 21, the balloon body 16 may be folded back so that a clear crease is formed, or the tip may be rounded. Since the balloon body 16 usually has a certain degree of thickness and elasticity, the tip of the balloon body 16 is rounded when folded back at the folding line 21. In this case, the tip of the folded balloon body 16 becomes the folding line 21.

[0084] It is preferable that the folding lines 21 are formed at least in the straight pipe section 13. Therefore, it is preferable that the balloon 10 has folding wing sections 20 formed by folding back the balloon body section 16 in the straight pipe section 13, and that the folding wing sections 20 are arranged overlapping the outer surface of the straight pipe section 13.

[0085] The folding lines 21 are preferably formed to extend parallel to the longitudinal axis direction or obliquely relative to the longitudinal axis direction. Furthermore, it is preferable to provide multiple folding wings 20 on the outer surface of the balloon 10. Forming the folding wings 20 in this manner makes it easier to fold the balloon 10 compactly.

[0086] The balloon body 16 may have a fold line (a valley fold line when viewed from the outside of the balloon 10) formed on one and / or the other circumferential side of the fold line 21, where the outer surface of the balloon body 16 is turned inward. In this case, the valley fold line preferably forms the base of the folding wing portion 20.

[0087] The folding wings 20 may be arranged on the outer surface of the balloon 10 so that all of the folding wings 20 are folded to one circumferential side, or some of the folding wings 20 are arranged on the outer surface of the balloon 10 so that they are folded to one circumferential side, and the remaining folding wings 20 are arranged on the outer surface of the balloon 10 so that they are folded to the other circumferential side. In Figures 13 and 14, the folding wings 20 are arranged on the outer surface of the balloon 10 in the former configuration, and in Figure 15, the folding wings 20 are arranged on the outer surface of the balloon 10 in the latter configuration.

[0088] 13, the folding wings 20 may be arranged to cover the wire 17 when the balloon 10 is in a deflated state. In this case, the folding wings 20 protect the drug layer 22 provided around the wire 17. This makes it difficult for the drug layer 22 to fall off the balloon 10 before the balloon 10 is delivered to the treatment target area.

[0089] 14, when balloon 10 is in a deflated state, wire 17 may be positioned radially outward of folding wing portion 20. In this case, when balloon 10 is expanded at a stenotic portion of a blood vessel, wire 17 is more likely to penetrate deeply into the stenotic portion, and drug layer 22 arranged around wire 17 is more likely to migrate efficiently from the inner surface of the blood vessel wall to the interior of the blood vessel wall.

[0090] 15 , when the balloon 10 is in a deflated state, the wire 17 may be arranged so as not to overlap the folding wings 20 in the circumferential direction. In other words, the balloon 10 may be folded so that the wire 17 is not positioned radially outward of the folding wings 20 and is not covered by the folding wings 20.

[0091] The balloon 10 may be folded as shown in Figure 13 or 14, and when the balloon 10 is in a deflated state, the wires 17 may be arranged so as not to overlap the folding wings 20 in the circumferential direction, as shown in Figure 15. Alternatively, the balloon 10 may be folded as shown in Figure 15, and when the balloon 10 is in a deflated state, the folding wings 20 may be arranged to cover the wires 17, as shown in Figure 13, or the wires 17 may be arranged radially outward of the folding wings 20, as shown in Figure 14.

[0092] This application claims the benefit of priority based on Japanese Patent Application No. 2024-077682 filed on May 13, 2024, and Japanese Patent Application No. 2024-232073 filed on December 27, 2024. The entire contents of the specifications of Japanese Patent Application No. 2024-077682 filed on May 13, 2024, and Japanese Patent Application No. 2024-232073 filed on December 27, 2024 are incorporated herein by reference.

[0093] 1: Balloon catheter 2: Shaft 3: Inner shaft 4: Outer shaft, 4A: Proximal outer shaft, 4B: Distal outer shaft 5: Hub 6: Fluid injection section 7: Guidewire port 8: Distal tip 9: Radiopaque marker 10: Balloon 11: Proximal sleeve section 12: Proximal tapered section 13: Straight tube section 14: Distal tapered section 15: Distal sleeve section 16: Balloon body section 17: Wire material, 17C: Centroid of cross-sectional outer edge of wire material 18: Specific shape 19: Specific region, 19A: Radially inner half region of specific region, 19B: Radially outer half region of specific region 20: Folding wing section 21: Bending line 22: Drug layer 23: Void 24: Crack 25: Protective layer

Claims

1. A balloon for a balloon catheter having a longitudinal axis direction extending from a proximal side to a distal side and radial and circumferential directions perpendicular to the longitudinal axis direction, wherein the balloon has a balloon main body and a wire arranged radially outward of the balloon main body, a straight tube section, a proximal tapered section located proximal to the straight tube section, and a distal tapered section located distal to the straight tube section, wherein the wire extends in the straight tube section parallel to the longitudinal axis direction or obliquely at an angle of 45° or less to the longitudinal axis direction, and a drug layer is provided from the surface of the wire to the outer surface of the balloon main body, and the maximum thickness of the drug layer in a region (hereinafter referred to as the "specific region") surrounded by a specific shape obtained by enlarging the outer edge of the cross section of the wire by a factor of two, centered on the centroid of the outer edge of the cross section of the straight tube section in the longitudinal axis direction, is thicker than the maximum thickness of the drug layer on the outer surface of the balloon main body outside of the specific region.

2. A balloon for a balloon catheter having a longitudinal axis direction extending from the proximal side to the distal side and radial and circumferential directions perpendicular to the longitudinal axis direction, wherein the balloon has a balloon main body and a wire rod arranged on the radially outer side of the balloon main body, and has a straight tube section, a proximal tapered section located proximal to the straight tube section, and a distal tapered section located distal to the straight tube section, wherein the wire rod extends in the straight tube section parallel to the circumferential direction or obliquely at an angle of more than 45° to the longitudinal axis direction, and a drug layer is provided from the surface of the wire rod to the outer surface of the balloon main body, and in a cross section of the straight tube section taken along the longitudinal axis direction and the radial direction, the maximum thickness of the drug layer within a region (hereinafter referred to as the "specific region") surrounded by a specific shape obtained by enlarging the outer edge of the cross section of the wire rod by two times, centered on the centroid of the outer edge of the cross section of the wire rod, is thicker than the maximum thickness of the drug layer on the outer surface of the balloon main body outside of the specific region.

3. A balloon as described in claim 1, wherein in a vertical cross section of the straight tube portion in the longitudinal axis direction, the maximum thickness of the drug layer in the radially inner half of the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region.

4. A balloon as described in claim 2, wherein in a cross section along the longitudinal axis direction and the radial direction of the straight tube portion, the maximum thickness of the drug layer in the radially inner half of the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region.

5. A balloon as described in claim 1, wherein in a vertical cross section of the straight tube portion in the longitudinal axis direction, the maximum thickness of the drug layer on the outer surface of the balloon main body portion other than the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region.

6. A balloon as described in claim 2, wherein in a cross section along the longitudinal axis direction and the radial direction of the straight tube portion, the maximum thickness of the drug layer on the outer surface of the balloon main body portion other than the specific region is thicker than the maximum thickness of the drug layer in the radially outer half of the specific region.

7. A balloon as described in claim 1, wherein, in a vertical cross section of the straight tube portion in the longitudinal axis direction, the drug layer is present between the outer edge of the cross section of the wire facing the outer surface of the balloon main body and the outer surface of the balloon main body.

8. A balloon as described in claim 2, wherein in a cross section of the straight tube portion along the longitudinal axis direction and the radial direction, the drug layer is present between the outer edge of the cross section of the wire facing the outer surface of the balloon main body and the outer surface of the balloon main body.

9. A balloon as described in claim 7 or 8, wherein a gap where no drug layer is present exists between the outer edge of the cross section of the wire facing the outer surface of the balloon body and the outer surface of the balloon body.

10. A balloon according to any one of claims 1 to 8, wherein cracks extending along the extension direction of the wire are formed on the surface of the drug layer.

11. The balloon of claim 10, further comprising a protective layer on the outer surface of the drug layer, the protective layer covering at least a portion of the cracks.

12. A balloon as claimed in any one of claims 1 to 8, wherein in a cross section perpendicular to the direction of extension of the wire, the radially outer half of the cross section of the wire has a widthwise length of the wire that is at least twice its radial length.

13. A balloon according to any one of claims 1 to 8, wherein the balloon has a proximal sleeve portion located proximal to the proximal tapered portion and a distal sleeve portion located distal to the distal tapered portion, the proximal end of the wire being fixed to the proximal sleeve portion and / or the proximal tapered portion, and the distal end of the wire being fixed to the distal sleeve portion and / or the distal tapered portion.

14. The balloon according to any one of claims 1 to 8, wherein the wire material is made of resin, metal, or a combination thereof.

15. A balloon according to any one of claims 1 to 8, wherein the surface free energy of the material constituting the surface of the wire is different from the surface free energy of the material constituting the outer surface of the balloon body.

16. A balloon according to any one of claims 1 to 8, wherein the surface free energy of the material constituting the surface of the wire is greater than the surface free energy of the material constituting the outer surface of the balloon body.

17. A balloon as claimed in any one of claims 1 to 8, wherein, in a deflated state, the balloon has folding wings formed by folding the balloon body with the inner surface facing inward, the folding wings being arranged on top of the outer surface of the balloon and covering the wire.

18. A balloon as claimed in any one of claims 1 to 8, wherein, in a deflated state, the balloon has folding wings formed by folding the balloon body with the inner surface facing inward, the folding wings being arranged overlapping the outer surface of the balloon, and the wire being arranged radially outward of the folding wings.

19. A balloon catheter comprising a balloon according to any one of claims 1 to 8.

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