Balloon catheter

Abstract

This balloon catheter is characterized by including: a catheter shaft that extends in an extension direction between the base end and the tip end; a balloon body (1B) that is provided to the catheter shaft, and that includes a balloon (3), which is radially expandable outward with respect to a central axis passing through the center of the catheter shaft, and elements (41, 42, 43), which are disposed on at least a portion of the outer peripheral surface of the balloon (3) and are integrally molded with the balloon (3); and a deformable covering body (5A) that covers at least side sections (401, 402) of the elements (41, 42, 43), the side sections being sections excluding distal ends (40P) that are radial-direction outer ends.

Description

Balloon catheter

[0001] The present invention relates to a balloon catheter.

[0002] Balloon catheters used for treating stenosed portions of blood vessels are known. Also, balloon catheters having elements on the surface of the balloon have been proposed. The elements act on the blood vessel in a state where the balloon is expanded. Patent Document 1 discloses a balloon catheter provided with a balloon having a plurality of wings as elements. The plurality of wings extend radially outward when the balloon expands. Therefore, the plurality of wings exert a high pressure on the tissue of the blood vessel due to the expansion of the balloon. As a method of forming a plurality of wings on the balloon, a method of forming a part of the balloon as a plurality of wings is exemplified.

[0003] Japanese Patent Application Laid-Open No. 2005-511187

[0004] When the balloon expands in the blood vessel, the balloon may move in a state where the element is in contact with the inner wall of the blood vessel. In this case, the position of the element may shift with respect to the treatment site.

[0005] An object of the present invention is to provide a balloon catheter capable of suppressing displacement of the position of the element with respect to the treatment site when the balloon expands.

[0006] The balloon catheter according to the present invention includes a catheter shaft extending in the extending direction between a proximal end and a distal end, and a balloon body provided on the catheter shaft, the balloon being expandable outward in the radial direction with respect to a central axis passing through the center of the catheter shaft, and an element disposed on at least a part of the outer peripheral surface of the balloon and integrally formed with the balloon, the balloon body including the element, and a deformable covering covering at least a side portion of the element, which is a portion excluding a tip portion that is an end portion on the outer side in the radial direction.

[0007] ]The balloon catheter according to the present invention can absorb the force that causes the balloon to move by the deformation of the covering when the balloon is inflated. As a result, the covering can prevent the element from moving relative to the blood vessel when the balloon is inflated. The covering can suppress displacement of the element relative to the treatment site.

[0008] In the present invention, the covering may further cover the tip of the element. In this case, the covering can prevent damage to parts of the blood vessel other than the treatment site from being caused by the element. Also, when the balloon is inflated, the portion of the covering that covers the tip of the element adheres closely to the inner wall of the blood vessel. As a result, the covering can prevent the element from shifting relative to the treatment site when the balloon is inflated.

[0009] In the present invention, the covering may cover the tip of the element when the balloon is inflated and when it is deflated. In this case, even when the balloon repeatedly inflates and deflates, the state in which a part of the covering covers the tip of the element is maintained. As a result, the covering can suppress the displacement of the element relative to the treatment site when the balloon is inflated, even when the balloon repeatedly inflates and deflates.

[0010] In the present invention, the portion of the covering that covers the tip of the element may be deformable to reduce its thickness when the balloon is inflated and stress is acting from the radial outward to the inward direction. In this case, the area over which the portion of the covering that covers the tip is in close contact with the inner wall of the blood vessel can be increased when the balloon is inflated. This makes it possible for the covering to suppress displacement of the element relative to the treatment site.

[0011] In the present invention, the portion of the covering that covers the tip of the element may be deformable such that its thickness is 90% or less when the balloon is inflated and stress is acting from the radial outward to the inward direction. In this case, the area over which the portion of the covering that covers the tip is in close contact with the inner wall of the blood vessel can be increased when the balloon is inflated. This makes it possible for the covering to suppress displacement of the element relative to the treatment site.

[0012] In the present invention, the portion of the covering that covers the side of the element may be deformable to increase in thickness when the balloon is inflated and stress is applied from the radially outward to the radially inward to the portion of the covering that covers the tip of the element. In this case, when the balloon is inflated, the portion of the covering that covers the side of the element absorbs the force that would cause the element to fall over. As a result, the covering can prevent the element from falling over.

[0013] In the present invention, the portion of the covering that covers the side of the element may be deformable such that its thickness becomes 110% or more when the balloon is inflated and stress is applied from the radially outward to the radially inward to the portion of the covering that covers the tip of the element. In this case, when the balloon is inflated, the portion of the covering that covers the side of the element absorbs the force that would cause the element to fall over. As a result, the covering can prevent the element from falling over.

[0014] In the present invention, the portion of the covering that covers the side of the element may be deformable so as to increase in thickness when the element is tilted. In this case, the portion of the covering that covers the side of the element absorbs the force that would cause the element to tilt further if it is tilted. As a result, the covering can suppress the element from tilting.

[0015] In the present invention, the element is made of resin and may be harder than the covering. In this case, the covering can properly treat the treatment site. Furthermore, because there is a difference in hardness between the element and the covering, when the balloon is inflated, stress can be concentrated on the element with relatively higher hardness. As a result, the element can properly treat the treatment site.

[0016] In the present invention, the Shore D hardness of the element may be in the range of 100 to 70, and the Shore D hardness of the coating may be in the range of 69 to 25. In this case, the element can appropriately treat the treatment site.

[0017] In the present invention, the covering may further cover the entire area of ​​the balloon except for the portion where the element is located. In this case, the covering can prevent the covering from detaching from the balloon. Furthermore, the covering can prevent the elements contained in the balloon from moving relative to the treatment site by preventing the balloon from moving relative to the treatment site when the balloon is inflated. In addition, the covering can prevent the balloon from being damaged.

[0018] In the present invention, the covering may be joined to the balloon body, or the covering may be integrally molded with the balloon body. In this case, the balloon catheter can prevent the covering from detaching from the balloon body.

[0019] In the present invention, the radial length between the tip and bottom of the element may be greater than the circumferential length of the bottom of the element adjacent to the balloon, with respect to the central axis. In this case, by increasing the amount of protrusion of the element and making the tip angle steeper, the element can appropriately treat the treatment site.

[0020] In the present invention, the thickness of the portion of the covering that covers the element may be greater than the thickness of the portion of the covering that does not cover the element. By relatively increasing the thickness of the portion of the covering that covers the element, the element can be efficiently prevented from moving relative to the blood vessel. Furthermore, by relatively decreasing the thickness of the portion of the covering that does not cover the element, the width of the balloon when it is deflated can be minimized. The covering can improve the passage of the balloon through the blood vessel.

[0021] This is a side view of the balloon catheter 10. This is a cross-sectional view of the balloon body 1B with the catheter shaft 1A and balloon 3 in an inflated state. This is a side view of the balloon body 1B with the catheter shaft 1A and balloon 3 in an inflated state. This is a cross-sectional view and a partially enlarged view taken along line I-I in Figure 3 from the direction of the arrow. This is a side view of the balloon body 1B with the catheter shaft 1A and balloon 3 in a deflated state. This is a cross-sectional view taken along line II-II in Figure 5 from the direction of the arrow. This is a cross-sectional view showing the balloon body 1B and covering 5A with the balloon 3 in an inflated state within the blood vessel 9. This is a cross-sectional view showing the balloon body 1B and covering 5A rotating within the blood vessel 9. This is a cross-sectional view showing element 41 and covering 5B in the first modified example. This is a cross-sectional view showing element 41 and covering 5C in the second modified example. This is a cross-sectional view showing element 41 and covering 5D in the third modified example. This is a diagram showing element 46 and covering 5E in the fourth modified example.

[0022] Embodiments of the present invention will be described with reference to the drawings. The drawings are used to illustrate the technical features that the present invention may adopt. The configurations of the devices described are not intended to be limiting, but are merely illustrative examples. For example, the length relationships of the parts in the cross-sectional views shown in Figures 2, 4, and 6-12 are shown with lengths different from the actual relationships for the sake of ease of understanding.

[0023] <Overview of Balloon Catheter 10> The balloon catheter 10 is a medical device used to dilate narrowed areas in blood vessels and arteries, or to cut open hardened areas. As shown in Figure 1, the balloon catheter 10 includes a catheter shaft 1A and a balloon body 1B.

[0024] <Catheter Shaft 1A> The catheter shaft 1A is tubular. A balloon body 1B is connected near one end of the catheter shaft 1A (referred to as the "tip 10D"). A hub 1C is connected to the other end of the catheter shaft 1A (referred to as the "proximal end 10P"). The hub 1C can supply compressed fluid to the balloon body 1B via the catheter shaft 1A.

[0025] The direction extending along the catheter shaft 1A is called the "extension direction D". The axis extending in the extension direction D through the center of the catheter shaft 1A is called the "central axis C". The radial direction centered on the central axis C is simply called the "radial direction". The cross-section obtained when the catheter is cut in a plane perpendicular to the central axis C is simply called the "cross-section". The radial direction that is close to the central axis C is called the "inward direction". The radial direction that is away from the central axis C is called the "outward direction". The circumferential direction centered on the central axis C is simply called the "circumferential direction".

[0026] As shown in Figure 2, the catheter shaft 1A has an outer tube 21 and an inner tube 22. The outer tube 21 and the inner tube 22 are both flexible. The inner diameter of the outer tube 21 is larger than the outer diameter of the inner tube 22. The inner tube 22 is positioned in the lumen of the outer tube 21, except for a predetermined portion (referred to as the "protruding portion 225"). The protruding portion 225 of the inner tube 22 protrudes from one end of the outer tube 21 (referred to as the "tip 21D"). The tip of the protruding portion 225 of the inner tube 22 corresponds to the tip 10D of the catheter shaft 1A.

[0027] As shown in Figure 1, the other end of the outer tube 21 corresponds to the proximal end 10P of the catheter shaft 1A. Compressed fluid supplied from the hub 1C flows through the space within the lumen of the outer tube 21 that is not part of the lumen of the inner tube 22.

[0028] The end of the inner tube 22 opposite to the tip 10D (referred to as the "proximal end 22P") is joined to the outer tube 21 at an intermediate position in the extension direction D. A guidewire G (see Figure 2) is inserted into the lumen of the inner tube 22. The balloon catheter 10 is an RX-type catheter. However, the balloon catheter 10 is not limited to being an RX-type catheter; it may also be an over-the-wire type.

[0029] The materials for the outer tube 21 and the inner tube 22 are not particularly limited. As an example of the materials for the outer tube 21 and the inner tube 22, polyamide resin can be used.

[0030] <Balloon Body 1B> The balloon body 1B deforms as its internal pressure changes in response to the supply of compressible fluid by the hub 1C. Figures 2, 3, and 4 show the balloon body 1B with the compressed fluid supplied. Figures 5 and 6 show the balloon body 1B with the compressed fluid discharged. The balloon body 1B has a balloon 3, a plurality of elements 4 (elements 41, 42, 43), and a covering 5A.

[0031] <Balloon 3> The balloon 3 is formed by a long, cylindrical membrane portion 30 along the stretching direction D. The thickness of the membrane portion 30 is approximately 0.01 mm as an example. The cross-sectional shape of the membrane portion 30 is approximately circular when the balloon 3 is inflated (see Figure 4). The material of the balloon 3 is, as an example, a thermoplastic resin. The material of the balloon 3 includes, for example, one or more types of polyamide elastomer, polyethylene, polyethylene terephthalate, polypropylene, polyurethane, polyamide, polyimide, polyimide elastomer, silicone rubber, etc. As shown in Figures 2 and 3, the balloon 3 has a base leg portion 31, a base tapered portion 32, a straight tube portion 33, a tip tapered portion 34, and a tip leg portion 35.

[0032] The base leg portion 31, base tapered portion 32, straight tube portion 33, tip tapered portion 34, and tip leg portion 35 correspond to the five sections obtained by dividing the balloon 3 along the extension direction D. The length of the straight tube portion 33 in the extension direction D is longer than the lengths of the base leg portion 31, base tapered portion 32, tip tapered portion 34, and tip leg portion 35 in the extension direction D.

[0033] The base leg portion 31 is connected to the vicinity of the tip 21D of the outer tube 21 by heat welding. The tip leg portion 35 is connected to the vicinity of the tip 10D of the inner tube 22 by heat welding.

[0034] The base tapered portion 32 is connected to the end of the base leg portion 31 that is close to the tip 10D of the inner tube 22. The outer diameter of the base tapered portion 32 increases from the end connected to the base leg portion 31 to the opposite end. The tip tapered portion 34 is connected to the end of the tip leg portion 35 that is away from the tip 10D of the inner tube 22. The outer diameter of the tip tapered portion 34 increases from the end connected to the tip leg portion 35 to the opposite end.

[0035] The straight pipe section 33 is provided between the end of the base tapered section 32 opposite to the end connected to the base leg section 31 and the end of the tip tapered section 34 opposite to the end connected to the tip leg section 35. The outer diameter of the straight pipe section 33 is substantially the same along the extension direction D.

[0036] The base tapered portion 32, the straight tube portion 33, the tip tapered portion 34, and the tip leg portion 35 cover a part of the protruding portion 225 of the inner tube 22 from the outside.

[0037] Balloon 3 expands when compressed fluid is supplied through the lumen of the outer tube 21. Balloon 3 deflates when compressed fluid is discharged through the lumen of the outer tube 21.

[0038] Figures 5 and 6 show the balloon 3 in its deflated state. In the deflated state, the balloon 3 has multiple wings 300 (wings 3A, 3B, and 3C). The multiple wings 300 are formed by folding the base tapered portion 32, the straight tube portion 33, and the tip tapered portion 34 of the membrane portion 30 of the balloon 3. The wings 3A, 3B, and 3C are arranged at equal intervals in the circumferential direction. The multiple wings 300 are close to the protruding portion 225 of the inner tube 22.

[0039] When compressed fluid is supplied to the contracted balloon 3, the balloon 3 deforms and expands. During the process of the balloon 3 moving from the contracted state to the expanded state, the multiple fins 300 are each eliminated. The base tapered portion 32, the straight tube portion 33, and the tip tapered portion 34 move radially outward and separate from the protruding portion 225 of the inner tube 22. Figures 2, 3, and 4 show the balloon 3 in the expanded state.

[0040] <Multiple Elements 4> The multiple elements 4 are provided on the outer circumferential surface of the membrane portion 30 of the balloon 3. Each of the multiple elements 4 extends along the stretching direction D from the base leg portion 31 to the tip leg portion 35 of the balloon 3. The multiple elements 4 are integrally molded with the balloon 3 and are made of the same material as the balloon 3. There are no joints between the multiple elements 4 and the balloon 3. For example, the balloon 3 and the multiple elements 4 are formed simultaneously by injection molding or blow molding.

[0041] The Shore D hardness of the multiple elements 4 is in the range of 100 to 70, which is harder than the Shore D hardness of the balloon 3. For example, the multiple elements 4 may be hardened by localized irradiation with ultraviolet light or by localized heating. In Figures 2, 4, 6, and 7, dotted lines are shown to indicate the boundary between the balloon 3 and the multiple elements 4 for ease of understanding. In the following, unless otherwise specified, the multiple elements 4 will be described assuming the balloon 3 is in an inflated state.

[0042] Multiple elements 4 protrude outward from the outer surface of the film portion 30. The multiple elements 4 include elements 41, 42, and 43. Elements 41, 42, and 43 are each arranged at equal intervals in the circumferential direction on the outer surface of the film portion 30.

[0043] As shown in FIGS. 2, 3, and 4, the shape of each of the plurality of elements 4 is a triangular prism, and the cross-sectional shape is a triangle. Each of the plurality of elements 4 has a tip portion 40P that is the radially outer end. The tip portion 40P is pointed. As shown in FIG. 4, each of the plurality of elements 4 has side portions 401 and 402 corresponding to two sides of the triangle in the cross-section. One end of each of the side portions 401 and 402 is connected at the tip portion 40P. The ends of the side portions 401 and 402 opposite to the tip portion 40P are connected to the outer peripheral surface of the film portion 30 of the balloon 3. A virtual curved surface extending in the circumferential direction between the end of the side portion 401 opposite to the tip portion 40P and the end of the side portion 402 opposite to the tip portion 40P is referred to as the "bottom portion 403". The bottom portion 403 is close to the film portion 30.

[0044] The radial length between the tip portion 40P and the bottom portion 403 corresponds to the protruding amount of the plurality of elements 4. The protruding amount of the plurality of elements 4 is denoted as "L1". The protruding amount L1 is, for example, about 0.3 mm. The circumferential length of the bottom portion 403 is denoted as "L2". The length L2 is, for example, about 0.2 mm. The protruding amount L1 is longer than the length L2.

[0045] The protruding amount L1 of the plurality of elements 4 varies according to the portions (base end leg portion 31, base end tapered portion 32, straight tube portion 33, tip tapered portion 34, and tip leg portion 35) of the balloon 3 where the plurality of elements 4 are provided. The protruding amount L1 of each of the plurality of elements 4 provided in the base end leg portion 31 is denoted as "L1(1)". The protruding amount L1 of each of the plurality of elements 4 provided in the base end tapered portion 32 is denoted as "L1(2)". The protruding amount L1 of each of the plurality of elements 4 provided in the straight tube portion 33 is denoted as "L1(3)". The protruding amount L1 of each of the plurality of elements 4 provided in the tip tapered portion 34 is denoted as "L1(4)". The protruding amount L1 of each of the plurality of elements 4 provided in the tip leg portion 35 is denoted as "L1(5)". The protruding amount L1(3) is larger than the protruding amounts L1(2) and L1(4). The protruding amounts L1(2) and L1(4) are each larger than the protruding amounts L1(1) and L1(5).

[0046] As shown in FIG. 6, when the balloon 3 is in a contracted state, the plurality of elements 4 are covered from the outside by the plurality of blades 300. Blade 3A covers element 41. Blade 3B covers element 42. Blade 3C covers element 41.

[0047] <Cover 5A> The cover 5A is formed by a film portion 50 that covers the balloon body 1B from the outside in the radial direction. As shown in FIG. 3, the entire region of each tip portion 40P (see FIG. 4), side portions 401, 402 of the plurality of elements 4, and the portion of the outer peripheral surface of the balloon 3 excluding the portion where the plurality of elements 4 are arranged is covered by the cover 5A.

[0048] The thickness of the film portion 50 of the cover 5A is different between the portion covering the plurality of elements 4 and the portion excluding the portion covering the plurality of elements 4. The thickness of the portion of the film portion 50 that covers the plurality of elements 4 (the tip covering portion 500 and side covering portions 501, 502 described later) is larger than the thickness of the portion of the film portion 50 excluding the portion covering the plurality of elements 4. More specifically, as an example, the thickness of the portion of the film portion 50 that covers the plurality of elements 4 is about 0.1 mm. As an example, the thickness of the portion of the film portion 50 excluding the portion covering the plurality of elements 4 is about 0.01 mm.

[0049] As shown in FIGS. 4 and 6, the state in which the cover 5A covers the balloon body 1B from the outside in the radial direction is maintained regardless of the state of the balloon 3. For this reason, the state in which the cover 5A covers the entire region of each side portion 401, 402, tip portion 40P of the plurality of elements 4, and the portion of the outer peripheral surface of the balloon 3 excluding the portion where the plurality of elements 4 are arranged is maintained regardless of whether the balloon 3 is in an inflated state (FIGS. 2, 3, 4) or the balloon 3 is in a contracted state (FIGS. 5, 6).

[0050] The material of the coating 5A is, for example, a thermoplastic resin, and includes one or more types such as polyamide elastomer, polyethylene, polyethylene terephthalate, polypropylene, polyurethane, polyamide, polyimide, polyimide elastomer, and silicone rubber. The Shore D hardness of the coating 5A is in the range of 69 to 25. The coating 5A is softer than the multiple elements 4. For this reason, the coating 5A is more easily deformable than the multiple elements 4.

[0051] The covering 5A is joined to the balloon body 1B. Therefore, the covering 5A is immovable relative to the balloon body 1B. The method of joining the covering 5A to the balloon body 1B is not particularly limited, but specific examples include joining with adhesive, joining by welding using heat, ultrasound, or laser.

[0052] Figure 7 shows the balloon body 1B in an inflated state within the blood vessel 9. When the balloon 3 inflates, the portion of the membrane 50 of the covering body 5A that covers the tip 40P of each of the multiple elements 4 (hereinafter referred to as the "tip covering portion 500") is sandwiched between the inner wall 9A of the blood vessel 9 and each of the multiple elements 4. As a result, stress acts on the tip covering portion 500 from the radially outward to the inward direction. Since the covering body 5A is more easily deformable than the multiple elements 4, this stress causes the covering body 5A to deform as follows.

[0053] First, the tip cover portion 500 is deformed to reduce its thickness. For example, the tip cover portion 500 is deformed until its thickness is 0.09 mm or less. In other words, the thickness of the tip cover portion 500 is deformed until it is about 90% or less of the thickness of the tip cover portion 500 and side covers 501, 502 of the membrane portion 50 where no stress is acting (about 0.1 mm). As a result, the contact area between the inner wall 9A of the blood vessel 9 and the covering 5A becomes larger than before the covering 5A was deformed. Consequently, the resistance component generated between the inner wall 9A of the blood vessel 9 and the covering 5A also increases, making it more difficult for the balloon body 1B to move in the stretching direction D relative to the blood vessel 9. Similarly, it becomes more difficult for the balloon body 1B to rotate in the rotational direction about the central axis C relative to the blood vessel 9.

[0054] Furthermore, the film portion 50 of the covering body 5A that covers the sides 401 of each of the multiple elements 4 (hereinafter referred to as "side covering portion 501") and the portion that covers the sides 402 (hereinafter referred to as "side covering portion 502") is deformed to increase its thickness. For example, the side covering portions 501 and 502 are deformed until their thickness is 0.11 mm or more. In other words, the thickness of the side covering portions 501 and 502 is deformed until it is approximately 110% or more of the thickness of the tip covering portion 500 and the side covering portions 501 and 502 of the film portion 50 where no stress is acting (approximately 0.1 mm). In this case, when a stress acting in a direction that causes each of the multiple elements 4 to fall over is applied to each of them, the side covering portions 501 and 502 become more able to absorb this stress. As a result, each of the multiple elements 4 becomes less likely to fall over.

[0055] Figure 8 shows the balloon body 1B, including balloon 3, in the process of changing from a contracted state to an expanded state. In this case, the balloon body 1B may rotate in a rotational direction about the central axis C. Figure 8 shows the case where the balloon body 1B rotates in a counterclockwise direction (direction of arrow Y).

[0056] As the balloon body 1B rotates, each of the elements 4 catches on the inner wall 9A of the blood vessel 9, and each of the elements 4 tilts in a clockwise direction. The protruding direction of the elements 4 is tilted with respect to the radial direction. At this time, the side covering portion 502 located upstream in the direction of rotation (direction of arrow Y) of the side covering portions 501 and 502 deforms so that its thickness increases. In this state, when a stress acting in a direction that would cause the elements 4 to tilt further acts on them, the side covering portion 502 becomes more adept at absorbing this stress. This suppresses further tilting of the elements 4.

[0057] The multiple elements 4 act on the treatment site of the inner wall 9A of the blood vessel 9 when the balloon 3 is inflated. For example, the multiple elements 4 incise the rigid treatment site (such as plaque). This improves blood flow to the treatment site and prevents restenosis of the blood vessel 9. Alternatively, for example, the multiple elements 4 apply localized pressure to the inner wall 9A of the blood vessel 9 when the balloon 3 is inflated, creating fine grooves. This allows the blood vessel 9 to expand appropriately as the balloon 3 inflates.

[0058] <Operation and Effects of This Embodiment> The balloon catheter 10 can absorb the force that causes the balloon 3 to move relative to the blood vessel 9 by the deformation of the covering 5A. As a result, the covering 5A can prevent the multiple elements 4 from moving relative to the inner wall 9A of the blood vessel 9. The covering 5A can suppress the displacement of the positions of the multiple elements 4 relative to the treatment site. In addition, the covering 5A can absorb the force that causes the multiple elements 4 to fall over by the side coverings 501 and 502 that cover the sides 401 and 402 of the multiple elements 4. As a result, the covering 5A can prevent the multiple elements 4 from falling over.

[0059] The tip cover portion 500 of the covering body 5A covers the tip portion 40P of each of the multiple elements 4. This allows the covering body 5 to prevent damage to parts of the inner wall 9A of the blood vessel 9 other than the treatment site from being caused by the multiple elements 4. In addition, the tip cover portion 500 of the covering body 5A adheres tightly to the inner wall 9A of the blood vessel 9 when the balloon 3 is inflated. This allows the covering body 5A to prevent the position of the multiple elements 4 from shifting relative to the treatment site on the inner wall 9A of the blood vessel 9.

[0060] The tip cover portion 500 of the covering body 5A covers the tips 40P of the multiple elements 4, regardless of whether the balloon 3 is in an inflated or deflated state. As a result, even when the balloon 3 repeatedly inflates and deflates, the tip cover portion 500 of the covering body 5A maintains its coverage of the tips 40P of the multiple elements 4. Therefore, the covering body 5A can prevent the position of the multiple elements 4 from shifting relative to the treatment site on the inner wall 9A of the blood vessel 9, even when the balloon 3 repeatedly inflates and deflates.

[0061] The tip cover portion 500 of the covering body 5A deforms to reduce its thickness when the balloon 3 is inflated and stress is acting radially from the outside to the inside. In this case, the tip cover portion 500 of the covering body 5A can be deformed to reduce its thickness to 90% or less. This increases the area in which the tip cover portion 500 of the covering body 5A is in close contact with the inner wall 9A of the blood vessel 9 when the balloon 3 is inflated. Therefore, the covering body 5A can suppress displacement of the positions of the multiple elements 4 relative to the treatment site on the inner wall 9A of the blood vessel 9.

[0062] The side coverings 501 and 502 of the covering 5A deform to increase in thickness when the balloon 3 is inflated and stress is acting on the tip covering 500 from the radially outward to the inward direction. In this case, the side coverings 501 and 502 of the covering 5A can deform to a thickness of 110% or more. As a result, when the balloon 3 is inflated, the side coverings 501 and 502 of the covering 5A absorb the force that would cause the multiple elements 4 to collapse. Therefore, the covering 5A can prevent the multiple elements 4 from collapsing.

[0063] When the balloon body 1B rotates, each of the multiple elements 4 tilts and inclins radially. At this time, the upstream side of the side coverings 501 and 502 in the direction of rotation deforms to increase in thickness, absorbing the force that would cause them to tilt further. As a result, the covering 5A can suppress the multiple elements 4 from tilting even further.

[0064] The multiple elements 4 are made of resin and are harder than the covering 5A. The Shore D hardness of the multiple elements 4 is in the range of 100 to 70, while the Shore D hardness of the covering 5A is in the range of 69 to 25. In this case, the balloon catheter 10 can appropriately treat the treatment site of the inner wall 9A of the blood vessel 9 with the multiple elements 4, which are harder than the covering 5A. Furthermore, because there is a difference in hardness between the multiple elements 4 and the covering 5A, stress can be concentrated on the multiple elements 4, which are relatively harder, during the process of the balloon 3 changing to an inflated state. As a result, the multiple elements 4 can appropriately treat the treatment site of the inner wall 9A of the blood vessel 9.

[0065] The covering 5A covers the entire area from the outside of the tip 40P, side portions 401, 402 of each of the multiple elements 4, and the outer surface of the balloon 3, excluding the portion where the multiple elements 4 are arranged. This prevents the covering 5A from detaching from the balloon body 1B. Furthermore, the covering 5A can prevent the balloon body 1B from moving relative to the treatment site on the inner wall 9A of the blood vessel 9 over a wide area of ​​the covering 5A. In addition, the covering 5A can prevent damage to the balloon 3.

[0066] By attaching the covering 5A to the balloon body 1B, the balloon catheter 10 can prevent the covering 5A from detaching from the balloon body 1B.

[0067] The protrusion amount L1 of each of the multiple elements 4 is longer than the circumferential length L2 of the bottom portion 403 of each of the multiple elements 4. This allows for a large protrusion amount of the multiple elements 4 and a steep angle at the tip portion 40P. The multiple elements 4 can appropriately treat the treatment site of the inner wall 9A of the blood vessel 9.

[0068] The thickness of the parts of the covering 5A that cover each of the multiple elements 4 (the tip covering 500 and the side coverings 501 and 502) is greater than the thickness of the parts of the covering 5A excluding the tip covering 500 and the side coverings 501 and 502. In this case, by making the thickness of the tip covering 500 and the side coverings 501 and 502 of the covering 5A relatively larger, it is possible to efficiently prevent the multiple elements 4 from moving or tilting relative to the inner wall 9A of the blood vessel 9. Furthermore, by making the thickness of the parts of the covering 5A excluding the tip covering 500 and the side coverings 501 and 502 relatively smaller, the width of the balloon 3 in its deflated state can be minimized. The covering 5A can improve the passage of the balloon 3 within the blood vessel 9.

[0069] <Modifications 1-4> The covering 5B according to Modification 1 differs from the covering 5A in that it covers only a portion of the outer surface of the membrane portion 30 of the balloon 3 from the outside, and does not cover the other portion of the outer surface of the membrane portion 30 of the balloon 3.

[0070] As shown in Figure 9, the covering 5B includes a tip covering 500, side coverings 501 and 502, and membrane coverings 503 and 504. The membrane covering 503 extends slightly in the circumferential direction from the end of the side covering 501 opposite to the tip 40P, along the outer surface of the membrane 30 of the balloon 3. The membrane covering 504 extends slightly in the circumferential direction from the end of the side covering 502 opposite to the tip 40P, along the outer surface of the membrane 30 of the balloon 3. The membrane coverings 503 and 504 corresponding to each of the multiple elements 4 do not cover the entire outer surface of the membrane 30 of the balloon 3. Therefore, the parts of the outer surface of the membrane 30 of the balloon 3, excluding the parts close to the multiple elements 4, are not covered by the covering 5B and are exposed.

[0071] The covering 5C according to the modified example 2 differs from the covering 5B in that it covers only the multiple elements 4 from the outside and does not cover the outer surface of the membrane portion 30 of the balloon 3.

[0072] As shown in Figure 10, the covering 5C includes a tip cover 500 and side covers 501 and 502. The tip cover 500 and side covers 501 and 502 cover the multiple elements 4 from the outside. On the other hand, the outer surface of the membrane portion 30 of the balloon 3, excluding the portion where the multiple elements 4 are provided, is not covered by the covering 5C and is exposed.

[0073] The covering 5D according to the modified example 3 differs from the covering 5C in that it does not cover the tip portions 40P of the multiple elements 4.

[0074] As shown in Figure 11, the covering 5D includes side coverings 505 and 506. The side covering 505 covers the outer portion of each side 401 of the multiple elements 4, excluding the vicinity of the tip 40P. The side covering 506 covers the outer portion of each side 402 of the multiple elements 4, excluding the vicinity of the tip 40P. The tip 40P of each of the multiple elements 4 is exposed and not covered by the covering 5D.

[0075] In modified example 4, the covering 5E covers a portion of the element 46, which has a pentagonal cross-sectional shape. As shown in Figure 12, the element 46 has side portions 406, 407, 408, and 409. Side portions 406 and 407 extend from the tip portion 40P in a direction inclined with respect to the radial direction. Side portion 408 extends perpendicular to the membrane portion 30 from the end of side portion 406 opposite to the end close to the tip portion 40P. Side portion 409 extends perpendicular to the membrane portion 30 from the end of side portion 407 opposite to the end close to the tip portion 40P.

[0076] The covering 5E includes side coverings 601, 602 and a membrane covering 603. Side covering 601 covers the side portion 408 of the element 46. Side covering 602 covers the side portion 409 of the element 46. Membrane covering 603 covers the portion of the membrane 30 excluding the portion on which the element 46 is provided. The tip portion 40P and the side portions 406 and 407 of the element 46 are exposed and not covered by the covering 5E.

[0077] A balloon catheter 10 containing any of the coverings 5B to 5E will have the same effect as a balloon catheter 10 containing covering 5A. In other words, the coverings 5B to 5E can prevent the multiple elements 4 from moving relative to the inner wall 9A of the blood vessel 9 when the balloon 3 is inflated. Furthermore, the coverings 5B to 5E can prevent the multiple elements 4 from collapsing when the balloon catheter 10 is inflated.

[0078] <Other Modifications> The present invention is not limited to the above embodiments, and various modifications are possible. The number of elements 4 is not limited to three, but may be one, two, four or more. The elements 4 may be provided only on the base tapered portion 32, the straight tube portion 33, and the tip tapered portion 34 of the balloon 3. Alternatively, the elements 4 may be provided only on the straight tube portion 33 of the balloon 3. The elements 4 may extend in a direction intersecting the extension direction D. For example, the elements 4 may extend in a circumferential direction centered on the central axis C, or they may extend spirally in the extension direction D. The shape of the elements 4 is not limited to an elongated shape. For example, each of the elements 4 may be divided at one or more positions in the extension direction D.

[0079] The cross-sectional shape of each of the multiple elements 4 is not limited to a triangle; it may be any other shape. For example, the cross-sectional shape of each of the multiple elements 4 may be a square or a trapezoid, or it may have a curved outer end.

[0080] The thickness of the coverings 5A to 5E may be uniform throughout the entire area, or it may vary from part to part. For example, the thickness of the coverings 5A and 5B may be greater in the parts that cover the multiple elements 4 from the outside (the tip covering 500 and the side coverings 501 and 502) than in the part that covers the outer circumferential surface of the membrane portion 30 of the balloon 3. The coverings 5A to 5E do not have to cover at least a portion of the balloon 3 and the multiple elements 4 over the entire area in the stretching direction D. In this case, a portion of the stretching direction D of at least a portion of the balloon 3 and the multiple elements 4 may be left exposed and not covered by the coverings 5A to 5E.

[0081] The coverings 5A to 5E may be integrally molded with the balloon body 1B. For example, a parison in which a tubular second material, which will form the covering 5A, is covered on the outer surface of a tubular first material, which will form the balloon body 1B, may be integrally molded by extrusion molding. During the extrusion molding process, the first material and the second material may be welded together at their respective contact points. By inflating this parison in a blow molding die, a balloon body 1B covered with the coverings 5A to 5E may be created. In this case, the detachment of the coverings 5A to 5E from the balloon body 1B can be prevented even more effectively.

[0082] The tip covers 500 of the coverings 5A to 5C may be divided by the tip portions 40P of the multiple elements 4 when stress is applied radially from the outside to the inside. In this case, the tip portions 40P of the multiple elements 4 may protrude outward from the coverings 5A to 5C.

[0083] The proportion of deformation of the coverings 5A to 5E is an example and is not limited to the above embodiment. The materials of the balloon 3 and the plurality of elements 4, and the coverings 5A to 5E are an example and are not limited to the above embodiment.

[0084] The thickness of the portion of the film 50 of the coating 5A that covers the multiple elements 4 may be the same as the thickness of the portion that does not cover the multiple elements 4.

[0085] The relationship between the protrusion amount L1 of each of the multiple elements 4 and the circumferential length L2 of the bottom portion 403 of each of the multiple elements 4 is not limited to the above embodiment. For example, the protrusion amount L1 and the length L2 may be the same, or the protrusion amount L1 may be shorter than the length L2. Furthermore, the entire object including each of the multiple elements 4 and the covering body 5A that covers them may be defined as, for example, an "element body". Here, if the protrusion amount of the element body is denoted as "L3" and the circumferential length of the bottom portion of the element body is denoted as "L4", the protrusion amount L3 may be greater than or equal to the length L4.

Claims

1. A balloon catheter comprising: a catheter shaft extending in the extension direction between a proximal end and a tip; a balloon body provided on the catheter shaft, the balloon being inflatable radially outward with respect to a central axis passing through the center of the catheter shaft; an element disposed on at least a portion of the outer surface of the balloon and integrally molded with the balloon; and a deformable covering that covers at least the side portion of the element, excluding the tip portion which is the radially outward end.

2. The balloon catheter according to claim 1, characterized in that the covering further covers the tip portion of the element.

3. The balloon catheter according to claim 2, characterized in that the covering body covers the tip of the element when the balloon is inflated and when it is deflated.

4. The balloon catheter according to claim 3, characterized in that the portion of the covering body that covers the tip of the element is deformable to reduce its thickness when the balloon is inflated and stress is applied from the radially outward to the inward direction.

5. The balloon catheter according to claim 4, characterized in that the portion of the covering body that covers the tip of the element is deformable such that its thickness becomes 90% or less when the balloon is inflated and stress is applied from the radial outward to the inward direction.

6. The balloon catheter according to claim 4, characterized in that the portion of the covering that covers the side portion of the element is deformable to increase in thickness when the balloon is inflated and stress is applied from the radially outward to the radially inward portion of the covering that covers the tip portion of the element.

7. The balloon catheter according to claim 6, characterized in that the portion of the covering body that covers the side portion of the element is deformable such that its thickness becomes 110% or more when the balloon is inflated and stress is applied from the radially outward to the radially inward portion of the covering body that covers the tip portion of the element.

8. The balloon catheter according to claim 1, characterized in that the portion of the covering body that covers the side portion of the element is deformable so as to increase in thickness when the element is in a tilted position.

9. The balloon catheter according to claim 1, characterized in that the element is made of resin and is harder than the covering.

10. The balloon catheter according to claim 9, characterized in that the Shore D hardness of the element is in the range of 100 to 70, and the Shore D hardness of the covering is in the range of 69 to 25.

11. The balloon catheter according to claim 1, characterized in that the covering further covers the entire area of ​​the balloon except for the portion in which the element is located.

12. The balloon catheter according to claim 1, characterized in that the covering is joined to the balloon body, or the covering is integrally molded with the balloon body.

13. The balloon catheter according to claim 1, characterized in that the radial length between the tip and bottom of the element is greater than the circumferential length of the bottom of the element adjacent to the balloon, with respect to the central axis.

14. The balloon catheter according to claim 1, characterized in that the thickness of the portion of the covering that covers the element is greater than the thickness of the portion of the covering that does not cover the element.

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